Multi-channel Vibration Instrument
Ri Yong Ho, a section head at the Faculty of Heat Engineering, has developed an instrument that can measure and analyze vibration of rotating machinery such as steam turbine generators real-time.
As a steam turbine generator is composed of rotors that are supported by their pedestals, vibration state of all the pedestals should be measured and analyzed at the same time by a multi-channel instrument. The multi-channel vibration instrument acquires vibration signals of up to 16 channels at high speed at the same time and transmits them to the computer so that one can measure and analyze vibration state of all the pedestals of turbine generators, diagnose vibration fault and decrease vibration level by taking necessary measures like balancing. The multi-channel vibration instrument is composed of analog signal processing circuit, key-phase pulse input circuit, digital signal processing circuit, USB communication circuit and power supply circuit. The analog signal processing circuit does overvoltage protection, filtering and amplification of vibration signals, and then sends them to the digital signal processing circuit. Digital signal processing is performed by a microchip, in which AD conversion of 16-channel analog signals, measurement of the rotating speed and vibration phase by key-phase pulse, saving of vibration waveforms and communication control take place. The acquired vibration waveforms of 16 channels are transmitted immediately to the microchip which has USB communication function by means of parallel communication mode and then they are real-time transmitted to computers through USB ports. In the power supply circuit, AC 220V power is converted to stable direct current voltages 5V and ±12Vand then supplied to every signal processing circuit. The computer performs digital filtering and integral of multi-channel vibration waveforms received from the vibration instrument, transforms vibration acceleration signals into vibration velocity signals and vibration displacement signals, calculates vibration amplitude to measure vibration level, and then makes vibration analyses such as spectrum analysis by fast Fourier transformation, phase analysis and trend analysis. Besides, it can perform one-plane balancing and two-plane balancing by method of influence coefficient, so field balancing of steam turbine generators can be realized. We can measure pedestal vibration by linking this instrument with piezoelectric acceleration sensors and electromagnetic speed sensors, and shaft vibration is also measurable when it is connected with eddy displacement sensors. The measurement range is 0~200㎛ in the case of pedestal vibration and 0~500㎛ in the case of shaft vibration, and the measurement accuracy is 2%.
Experiment Device for Vibration Measurement of Ship Hull Model
The research group led by Pae Ho Rim, a section head at the Faculty of Shipbuilding and Ocean Engineering, has developed an experiment device for measuring natural frequency of a ship hull.
The device measures the natural frequency of a ship hull model by the principle that resonance occurs when natural frequency is coincident with the frequency of forced vibration caused by decentration mass. The device consists of ship hull model, vibration generator, unit for motor velocity control, frequency sensor, acceleration sensor, amplification and integration circuit, communication interface, user interface, etc. The model is 1.2 metres long, 0.1 metres wide and 0.1 metres high. The cross section is rectangular and the bow and stern assume a pyramidal form. The user interface shows the graphs and values of real-time signals of revolution, displacement, acceleration and velocity.
Test Method for Crack Selection in 10kV Pin Insulators
Kim Ryul, a researcher at the Faculty of Electrical Engineering, has realized selection of crack insulators from a pile of 10kV pin insulators by data processing of thermal shock sample breaking test and a corona short-circuit nondestructive test device. Compared with previous selection methods by electric penetration breakdown test, this method provides more safety and lower production cost. In addition, as it uses nondestructive electric tests to sort out crack insulators, the reliability of production pile of insulators can be further improved. This method is constructed with several stages: determination of size of 10kV pin insulator piles and samples, thermal shock sample destructive test, state decision of pass or pass failure of production piles by processing test data, determination of acceptance probability by quality control software and of the number of faulty insulators, and selection of crack pin insulators by the corona short-circuit nondestructive selection device. This thermal shock test costs less and provides 1.4 times higher accuracy than the previous electric penetration breakdown test. To estimate cracks in 10kV pin insulator piles, previous binomial distribution was replaced with noncentral t-distribution, which reduced the number of samples to half and improved the accuracy of acceptance probability of piles and the calculation of the number of crack insulators by 1.2 times. Instead of electric penetration breakdown test devices, corona nondestructive test devices were used, which made it possible to select 100% of crack insulators from passed piles.
DC-DC Chopper Experimental Equipment
Ho Tong Chol, a researcher at the Faculty of Electrical Engineering, has developed DC-DC chopper experimental equipment, a part of a power electronics integrated laboratory table. It is designed to enable experiments on typical DC-DC converters ― Buck, Boost and Buck-Boost. It can easily get an operational waveform at any point thanks to the terminals placed on the front-plate, it is supported by AC 220V as main power source, and the circuit diagrams of the front-plate are intuitive and plain enough to provide users with convenient environment for experiments on a certain converter. This equipment, composed of power supply, control block, driving circuit, main circuit, load and filter, is useful for raising or dropping static DC 12V and for measuring some parameters such as duty cycle, voltage and current ripple rate, instantaneous value, mean value, etc. The control block using current typed PWM integrated circuit SG3525 compares the carrier in 32.5kHz with DC voltage(0~3.3V) before it generates a PWM pulse at that comparison position. This process is observed at the terminals. Additionally, since it includes a soft-starting circuit, you can increase the duty cycle smoothly so that no shock current flows into the main switch even when it starts on the maximum duty cycle. The control range of duty cycle is 0.2 to 0.8. The control block is also available for the control of a transformer isolated DC-DC converter since it has two ground separated power supplies, which is useful for the experiment on a half-bridge DC-DC converter. The driving circuit guarantees a reliable and safe switch of the main device. The driving circuit is fed from unipolar power source. The main circuit consists of a main switching device, a reactor, FRD, a capacitor and a current sensing resistor. The load is a resistor in 200Ω and it can also include a filter when necessary. The newly-developed experimental equipment is useful to students, researchers and teachers who major in power electronics.
Electrode Material for Electric Spark-alloying Developed
Sim Jae Rim, a section head at the Faculty of Materials Science and Technology, has established a way of making WC-Co-B4C system electrode material for electric spark alloying and an alloying process by this material so that the service life of tools and machine parts could get more than 2.5 times as long. B4C in the material has a good effect on the formation of alloying layers since it plays the role as flux which decreases the amount of oxide scale made during electric spark alloying. It also decreases the amount of oxides of low hardness and helps the formation of carbides of high hardness. The reasonable electric conditions for electric spark alloying by WC-Co-B4C system electrode material are short circuit current I=9A, U=24V, C=420㎌ and t=2min/cm2. The thickness and hardness of an electric spark alloying layer by the new material are higher, that is, 90㎛ and 23.5GPa respectively, compared to 70㎛ and 19.5GPa by previous WC-Co system electrode material. Electric spark alloying by WC-Co-B4C system electrode material forms alloying layers of high hardness on the surfaces of tools and machine parts, which leads to the lengthening of their working life.
Cryogenic Liquid Tank for Storage of Oxygen Liquid Built
The research team led by Ri Ju Hyok, a section head at the Faculty of Heat Engineering, has designed and built a cryogenic liquid tank for storage of oxygen liquid. The tank is manufactured to store oxygen liquid produced by cryogenic distillation process for a certain period and to supply it in either liquid or gas form. It is composed of an inner body for storage of oxygen liquid, an outer body, a pipeline for injection and exhaustion, safety factors including checker valves, safety valves, pressure control valves, a level meter and manometers and a self-evaporator for increasing the pressure inside the tank. The space between the inner and outer bodies is filled with thermal insulation material expanded perlite and made vacuous to reduce evaporation loss and to keep cool. The problem of preserving the cold to minimize cold loss by a heat bridge was solved, which decreased daily loss to only 0.3~0.8%. The degree of vacuum in the insulated space is 1.3Pa, and the total heat conductivity of the expanded perlite is 0.017W/(m•K). With all these advantages it can also be used for storage of other cryogenic liquids like nitrogen, argon, etc. as well as oxygen.
Indoor Base Station Antenna for Mobile Communication
Kim Myong Il, a vice dean at the Faculty of Communications, has invented an indoor antenna for mobile communication. Compared with previous antennas, this antenna has several advantages ― it ensures enough matching, gain and horizontal omni pattern in a wide band of frequencies; it is easy to feed, produce and assemble; it is light, good-looking and easy to install. Consisting of a cone monopole, a double cone reflection panel, a curved plastic protection lid and coaxial feeding structure, the antenna assumes horizontal omni pattern in a wide range of frequency such as GSM, WCDMA, LTE, etc. With the gain of 3dBi, it can provide indoor mobile communication service in areas such as the underground of a building where mobile communication service cannot reach. As a wide-range radiator, a cone monopole has top and bottom panels made of metal (Oblique angle is 25.5, radii are 12mm and 21mm respectively.), with an impedance of 50Ω and a wide radiation area. So it is of nearly omni directional pattern on the horizontal plane. Vertical radiation can be controlled by a double cone reflection panel consisting of a primary cone reflection panel, a plain reflection panel, an upper cone reflection panel for coaxial feeding and it can bring a gain of 3dBi. The inner conductor of a feeding coaxial cable is connected to the bottom panel and the outer conductor is linked to the reflection panel. The impedance of the antenna can be controlled by inserting an inclined line between the cone monopole and the reflection panel. Therefore, the impedance of the antenna remains constant in a wide frequency range. What is more, it is easy to install on the wall and it is covered tightly with a radome made of glass fiber plastic in order to prolong the life span and give a good-looking appearance. In a wider frequency range(756~1 063/1 670~2 777MHz) than in the frequency range of former wire monopoles, the gain is 3.2dBi, which is 1.1dBi higher than former antennas (2.1dBi), so the service bound gets 1.4 times wider than before. The antenna is light, easy to install and meets aesthetic requirements.
Insulation Bushing for 10kV Electric Boiler
Kim Ryul, a researcher at the Faculty of Electronics, has developed a new insulation bushing for a 10kV electric boiler that conforms to the operating conditions of the boiler and guarantees high reliability. Unlike prior bushings of a cylindrical shape for a 3-phase 3kV electric boiler, a newly-developed one is of a conical shape, satisfies the operating conditions for a 10kV electric boiler and is more reliable and lighter. As its head has been changed into a ring type, they can increase yield, which means it can help reduce the level of environmental pollution and save raw and other materials. The new bushing is lighter by 0.7 times each, which means it has now become cheaper to make. What is more, it is 2.4 times higher in dielectric strength, 3.3 times in working voltage, 1.25 times in output power, 2.7 times in 5-minute upkeep water pressure and 0.65 times lower in maximum current, which offers a scientific guarantee of the operating conditions and reliability of a 10kV electric boiler. The yield has increased up to 93%.
Development and Introduction of Single-Phase Grid-Connected Voltage Sourced Inverter with Reactive Power Control
A research team led by Hong Yong Jun, a researcher at the Institute of Electric Engineering, has developed and introduced a single-phase grid connected VSI(Voltage Sourced Inverter). It can not only transfer active power to the national power grid by converting the DC power generated by PV(Photovoltaic) modules into AC active power and synchronizing it with the voltage and frequency of the grid, but also control reactive power independently. They realized the control of reactive power in the grid-connected VSI by applying the IRP (instantaneous reactive power) theory, the base of the FACTS(flexible AC transmission system). For this control, they had to ensure the exact tracking of the frequency of the grid voltage by introducing the fictitious phase by the SOGI(second-order generalized integrator) and FLL(frequency locked loop). Then, they took control of grid injected current by a PR(proportional resonant) regulator with proper parameters, and added anti-islanding detection by active frequency drift. The THD(total harmonic distortion) of grid-injected current is 3.6% and the time required for anti-islanding detection is less than 0.1s.
10kV Electric Boiler Developed
A research group led by Jang Ki Ho, a section head at the Faculty of Heat Engineering, has developed a 10kV electric boiler designed to use the electricity from a power system directly, and they are now working hard to make further achievements in their research. Boilers are largely divided into two types, i.e. a low voltage electric boiler (LVEB) and a high voltage electric boiler (HVEB). In a LVEB, heat is generated by Joule heating effect in an electrical resistor as an electrical heating element below 380V and is transferred to fluids. Usually, the electrical heating element used in a LVEB produces several kilowatts of thermal power. However, hundreds or thousands of kilowatts are needed to heat various kinds of liquid for swimming pools, ponds used for aquaculture, sensitive products used in chemical and agro alimentary processes and buildings. The heat power output of boilers used for controlling the load in a wind power station or a nuclear power station is the same. Even if several heating elements below 380V can be used as one, it remains uneconomic, because it needs a transformer that maintains the supply system voltage at 380V, and it also causes a considerable energy loss. On the contrary, an HVEB(10kV) offers several advantages: it produces thousands of kilowatts of high electro-thermal power, it needs comparatively low investment, it is easy to make, and it can be operated without a transformer from the direct supply from an electric power system.
The problem is the safety of a high-voltage electric boiler. It is difficult to predict the amount of thermal power in the step of its design because it depends on the temperature, velocity and specific resistance of the fluid that are also changed in relation to each other. To solve these problems, they proposed a 10kV electric boiler equipped with a ceramic insulation tube inside and determined its geometrical sizes and operation parameters through a numerical analysis of coupled thermal, hydro mechanical and electrical fields in the water heating process. On the basis of this, they completed it through tests and practices. The investment of an 10㎸ electric boiler is under ½, and the installation area under ¼, compared to a LVEB of the same capacity. And there is no consumed power due to the operation of a transformer.
Cryogenic Liquid Oxygen Vaporizer Invented
A research group led by Ri Ju Hyok, a section head at the Faculty of Heat Engineering, has invented a vaporizer that vaporizes cryogenic liquid oxygen to supply to consumers. It is an atmospheric source cryogenic vaporizer that turns cryogenic liquid oxygen into gas by cryogenic distillation method. In practice, the demand for oxygen is unpredictable. To meet this flexible demand, liquid oxygen is usually stored in the cryogenic tank and is vaporized whenever needed. The vaporization of liquid oxygen is conducted by means of a cryogenic vaporizer. The vaporizer is a vertical heat exchanger, its cross section is of an 8-pointed star type and it vaporizes cryogenic liquid by atmospheric heat. To determine the optimal parameters of a vaporizer, they studied 4 items: growth process of frost on the surface of the heat exchanger when liquid oxygen is vaporized, the property of frost, the pulse phenomenon in the heat transfer pipe and the destruction of frost on the surface, and the characteristics of air flow in the surrounding of a heat exchanger.
The cryogenic oxygen liquid vaporizer is extruded of aluminum alloy of good conductivity. As its heat source is based on only the air in the atmosphere, environmental problems such as pollutant emission and noises are not arisen. It is also applicable to the vaporization of other cryogenic liquids like nitrogen, argon, etc. as well as oxygen.
Computerized Experiment Device for Characteristics of Glow Discharge Plasma
Choe Yong Son, a researcher at the Faculty of Physics, realized the computerization of an experiment device to measure the characteristics of glow discharge plasma. Compared to the previous devices with analog meters, the computerized device is equipped with an embedded system and a touch-panel interface, which makes it possible to supervise and analyze experimental processes, and to display the results. It also ensures high accuracy in measurement and short time of measurement along with intuitiveness and effectiveness of experiments. The device consists of a power supply, a probe voltage stabilizer, a triangular signal generator, a discharge current sustainer, a current-to-voltage converter, a voltage signal detector, a matching unit, and a computer. The main characteristics to measure are electron density and electron temperature. A linearly increasing voltage is applied to the electrostatic probe, which is placed in the discharge region, and the current to the probe is captured at a regular interval, in order to gain voltage-current measurement points of the probe. These measured data are treated by 3-order spline interpolation and then by weighed polynomial method to obtain a voltage-current curve of the probe. Necessary features are to be derived from the characteristic curve, and these features are utilized to determine electron temperature and electron density. All these operations are automatically performed through its embedded system and touch-panel interface.
This device can increase the measurement accuracy of probe voltage and current by more than 20 times and, as a result, as many measurement points as possible are available. Therefore, we can eliminate scale errors, which were indispensable in the past, and decrease random errors down to below 0.5% (in analog meter: 4.2%). In addition, offline experiments may become possible by the combination of serial communication and network communication.
Shoe Design Serial Expansion Program Developed
Choe Song Bom, a section head at the Faculty of Information Science and Technology, has developed an image processor to obtain input images from hand-based shoe design images, and on the basis of it, he has continued to invent a new method of serial expansion and realize it in a serial expansion program.
This program consists of 3 parts: noise reduction, contour highlight, and serial expansion. Its application reduced design hours from 10 to 3 and improved design accuracy from 90% to 98%.
Network Management System Using Simple Network Management Protocol
In keeping with the actual conditions where communication equipment is on the increase in its kind and scale, the research team led by An Chong Il, a researcher at the Faculty of Information Science and Technology, has developed a network management system using a simple network management protocol that enables the integrated management of individual pieces of communication equipment. Thanks to it, it became possible to manage different pieces of existing communication equipment in an integrated way and also to satisfactorily supervise and manage newly-added ones.
Debinding Method in MIM Products
The research group led by Sim Jae Rim, a section head at the Faculty of Materials Science and Technology has succeeded in the research into an effective method of debinding in metal injection molding (MIM) products.
They put MIM products made with paraffin-based binder in a benzol-acetone solution to remove soluble binder before heating them to remove insoluble binder, thus increasing debinding rate by more than 5% and reducing the duration of debinding by more than 2 hours.
DNA Computing Simulation Program Developed
The research team led by Kim Sung Nam, an institute head at the Faculty of Information Science and Technology, has developed a DNA computing simulation program to perform parallel computations on a personal computer by applying a DNA encoding process, a branch of biochemistry, to the optimum solution of intellectual problems.
The program consists of 3 parts: monkey-banana problems, TSP problems and word association problems. This program is able to generate all possible paths and examine the possibility of optimization at the same time in parallel by simulating the DNA computing programmatically, in contrast to traditional optimal path-finding methods that generate all possible paths and then find one among them by examining conditions one by one. The average time of solving problems is about 20s (Core i3) and the accuracy reaches 95%.
Korean Braille Character Reader of Our Style
The research group led by Ma Min Gon, vice dean of the Faculty of Information Science and Technology, has developed a Korean braille character reader which converts raised letters read by an image input device into a character code readable by ordinary people.
When books published in raised type for the blind to read by groping are read by an image input device like a scanner, the raised parts are shown in dim dots. In order to extract these dim dots more precisely, they proposed and realized several new basic methods: binarization by wavelet difference image, tilt estimation by Hough conversion, dot extraction by dot database and Maharanobis distance for precise extraction without being affected by the scanning direction, charline extraction from dots capable of strongly overcoming noises, substitution of braille code for unicode by bidirection scanning, postprocess based on geometrical position of dots, etc.
Thus, they were able to raise the extraction precision up to 96% and the recognition speed up to 1 second per page.
A Screw Rolling Process with Individually Driven Rollers Established
A research group led by Ri Yong Min, a researcher at the Faculty of Materials Science and Technology, has developed a screw rolling mill with individually driven rollers and established a rolling process which can produce bars of more than 20mm in diameter through one pass without a roller change from round steel of 50mm in diameter, consuming less power. They will no longer need an ordinary light section rolling mill in machine factories and repair bases that have a great demand for bars in various diameters. In this rolling process, round steel of 50mm in diameter is heated to 850~950℃ in a heating furnace and is rolled into bars of 20mm in diameter through one pass in a cantilevered 3-helical rolling mill with individually driven rollers that has a large feed angle and an elongation angle before they are cut into necessary lengths.
Thus, they can produce bars of different diameters from short scrap iron by changing no rolls but adjusting the roll gap, and ensure the metal yield of more than 99% and the roundness of ±0.1.
C/C++ Programming Evaluation System Developed
Kim Won Ok, a researcher at the Faculty of Information Science and Technology, has developed a C/C++ programming evaluation system to raise practical programming skills of students who are learning C/C++ programming including those who are receiving distance education, and to make an accurate evaluation of the programming assignments performed by them.
What she has done includes the combination of web and other applications by TCP socket communication, the implementation of a C/C++ programming environment by C++ compiler and I/O stream pipeline, accurate evaluation of assignment performance, and the security of learning-related data including assignments by user certification, copy paste protection and encryption.
She herself tried making and running a program so as to make a programming tool and a system for evaluating programming accuracy. This helped raise students’ programming skills and enthusiasm for study, and evaluate their assignment performance rapidly and accurately.
Newly-Developed Java API Compound Retrieval Program
Pak Il Chol, a researcher at Faculty of Information Science and Technology, has developed a Java API compound retrieval program on the basis of the collection of code snippets and feature extraction. In this program it is possible to realize ranking of code snippets suitable for user intention from their application degree and brevity degree. He increased the rate of indexing by 0.3GB per hour and the precision and recall by 6% and 9% respectively, which resulted in the improvement of the development speed and quality of programs. Thus, he ensured the guarantee for reducing the labour and time needed for program development to one tenth.
Optical Passingtime Detector
Kong Myong Il, a researcher at Semi-conductor Institute, and his research group have developed PTC (positive temperature coefficient) resistance material necessary for constant operation of facilities under the condition of room temperature even in low-temperature zones, and they have been expanding their achievements. This material provides room temperature resistance of 20Ω, Curie temperature of 30℃ and temperature coefficient of resistance of over 18%/℃.
Optical Passingtime Detector
Kang Hwi Song, a researcher at Faculty of Electronic Engineering, and his research group have succeeded in manufacturing an Optical Passingtime Detector using infrared optical technology and Zigbee wireless communication and are expanding their achievements. This detector ensures speed measurement accuracy of 0.01s in a 30-meter section which is an important item in selecting and training reserve footballers.
As it is portable, it can be taken for camping drill and also be used in outdoor conditions with high illuminance as well as indoors. Moreover, it offers high stability and accuracy of speed measurement. The range of time measurement is 0~100s and the measurement accuracy is 0.01s.
Ways to Improve Simultaneous Initiation Property
Pak Thae Un, a section head at Faculty of Mining Engineering, studied and introduced a simultaneous blasting method by a high-voltage blaster whereby they could improve rock cutting property by enhancing the effects of simultaneous blasting in blasting operations.
They applied voltage of over 150v to each electric igniter linked to tens of detonators connected in series in the blasting circuit network with a high-voltage blaster generating high voltage impulse in order to cause discharge explosion effect, thus reducing the average detonation time to 4.7±1ms. It resulted in the improvement in the effects of simultaneous blasting of blasting hole charges, which meant far more improvement in rock cutting property.
Air Classifier for Fine Products Developed
A research group with Sin Tong Ho, a researcher at Faculty of Mining Engineering, as a leader has developed and introduced a vertical shafting air classifier equipped with a rotor cage with high classification efficiency and an assistant air pipe that makes it possible to realize accurate classification as well as to control classification size in the processes of dry fine grinding or microfine grinding-classification of fireproof material, chemical material, abrasive material, etc. They selected a reasonable structure and made a hydrodynamic analysis of the motion characters of mineral particles in the rotor cage. On this basis, they made an optimal design of structural and operational parameters and put them on a scientific basis so that they could ensure needed particle size distribution of powder products and high productivity.
The feed size of this classifier is less than 0.1mm and its classification size is 10~74㎛.
Highly Efficient Cogeneration Power System Introduced
Kim Myong Chol, teacher from Faculty of Heat Engineering succeeded in building and introducing a cogeneration power system, which can provide steam for production of higher pressure and raise the utility rate of energy to the maximum by the mode of combining electricity and heat. He remodeled the ventilation part of bleeder condensing turbine in order to minimize the loss of effective work arising in steam depressing process for the supply of production steam. Thus, he provided scientific and technological guarantee of saving natural resources of our country and supplying electricity and steam for production according to consumption process by raising the utility rate of energy in many factories and enterprises.
The pressure of production bleeder steam of the cogeneration system is 1MPa, the temperature of the steam is 270℃ and the amount of supply of steam for production is 0~30t/h.
Internet of Things Built
A research team including Ri Se Hyong, section leader from Faculty of Automation Engineering succeeded in building the internet of things in an enterprise. The team built internet of things, the overall system of interconnected physical objects that can make material transportation IT-based and effectively observe and control various kinds of equipment and different processes. Accordingly, they converted the enterprise into an intelligent factory where production lines are made IT-based and automated, and improved the quality and productivity of products.
Well-Reputed Heat Radiation Panel for Cooking Oven
Kim Kon, researcher from Faculty of Applied Chemical Engineering studied and introduced gas-saving heat radiation fire-grate with our own raw materials, which is useful to reduce food processing time and save gas by promoting combustion and thermal efficiency. He designed the most appropriate structure of heat radiation fire-grate to apply it to various kinds of gas cooker, and put the synthesizing method, materials and thermodynamic characteristics etc. on a scientific basis. Flame temperature of heat radiation fire-grate is 70~120℃ higher than those of general cast fire-grates, flame color is orange and thermal efficiency is more than 75%.
Realization of Domestic Production of Brush for Shaft Grounding
The research group led by Jang Song Ok, laboratory head at the Faculty of Mining Engineering succeeded in manufacturing a natural graphite brush for shaft grounding and is trying to make further achievements in their research. They proved scientifically that it is possible to make a brush for shaft grounding with natural graphite and decided the structure, quality and operation system of the material for the brush with high capacity of electro motion and contact property and with improved wear property. The permissible current density of the brush is 20~30A/㎠, the ratio of wear is about 0.3㎜/1 000㎞ and the spring pressure is around 20㎪.
The research group led by Choe Chol Min, laboratory head at the Faculty of Materials Science and Technology succeeded in manufacturing a splint using AM (additive manufacturing) and is trying to make further achievements.
This light splint of good air permeability manufactured by FDM (fused deposition modeling) helps relieve patients from their burden, reduce complications like skin diseases to shorten the period of treatment. Figure 1 shows the CT photograph of a patient. Figure 2 displays the model of a splint manufactured with Solidworks using its photograph. Figure 3 shows the arm of a patient who wore the above mentioned splint just after the day of operation.
Domestic Production of Thermo-pH Responsive Polymer
Jong Kwang Hyok, the head of Laboratory at Faculty of Applied Chemical Engineering and his research group succeeded in producing non-toxic low-cost nano micellar functional material that can be used as starch derivative for drug delivery, high purity refiner of the object material and environmental improvement material with our own raw material.
This functional polymer based on starch guarantees 15~80℃ of thermal response range, ±0.1℃ of response accuracy, 1~10.4 of pH response range, and 50~90mg/L of micelle critical concentration range.
Domestic Production of Non-magnetic Hard Alloy
Researcher Hong Myong Son at Faculty of Materials Science and Technology and his research group succeeded in producing non-magnetic hard alloy which contains no cobalt with domestically available raw materials. This kind of alloy is used as the basic material of molding tools and is urgently needed in the various sectors of the national economy.
The hardness of this alloy is more than HRA 91, the bending strength more than 1.8GPa and the saturation magnetization strength less than 3Gs.
Local Provision of Alumina Insulation Porcelain Realized
The research team led by Kim Ryul, a researcher at the Faculty of Electrical Engineering, has developed metallic oxide lightning arrester for high voltage based on the domestic resources, thus contributing to the regular operation of electric equipment.
The non-interval metallic oxide lightning arrester is made by sintering the mixture of zinc oxide and other oxides such as arsenic oxide, aluminium oxide at over 1150℃. The voltage degree of nonlinear resistance of the metallic oxide lightning arrester is over 318V/mm.
Local Provision of Alumina Insulation Porcelain Realized
The research group including Kim Ryul, a researcher in the Faculty of Electrical Engineering contributed to the development of ultra high voltage suspension insulator based on the domestic resources.
It is proved that the newly developed plastic alumina insulator can be used as ultra high voltage suspension insulator, with its insulation property fully assured and all the characteristic features such as bending strength, tensile strength and thermal break down temperature much higher than feldspar insulator which is currently being used. The bending strength is over 160MPa and tensile strength over 55MPa and thermal break down temperature over 182℃.
Automation Efficiency of Database Construction Process Enhanced
Research team led by Ma Min Gwon, head of a department, Faculty of Information Science and Technology, improved the performance of Multi lingual OCR that changes text images into editable document and thus enhanced the level of making data input process IT-based and scientific.
This Multi lingual OCR, which has already been introduced into several units and proved greatly beneficial, automatically discriminates and recognizes languages including English, Russian, Chinese and Japanese and its recognition rate is above 99% on an average.
Robot Visual Servo System Developed
A research team led by Prof. Jang Kwan Sik, a head of the department of Faculty of Mechanical Science & Technology developed Robert Visual Servo System, making high-speed and robotized the reloading of products flowing in disorder out of the continuous flow production processes.
They successfully designed and manufactured the structure of delta robot working cell with vision and control device, realizing proper coordination control using visual feedback. They have still been studying hard to enhance its accuracy, speed and stability.
Realization of Smart Manufacturing System
A research team led by Prof. Jong Il Chol, head of a department of the Faculty of Automation Engineering achieved a great success in applying the smart manufacturing system to one enterprise.
They, having deepened the research in a short time, constructed the smart manufacturing system by developing the core technologies of the intelligent production system such as virtual physics production system, vast amount of data-processing technology and artificial intelligent control technology.
By doing so, they have turned the enterprise into labor- and energy-saving and technology-integrated one so that they could improve the quality of goods and increase its output while saving a lot of labor, materials and electricity.
Textile CAD/CAM System Established
Textile CAD/CAM system researched and completed by the research group headed by Jong Il Chol, laboratory head of the Faculty of Automation Engineering, was introduced to light industry mills and enterprises that produce towels, blankets, fabrics and knitted goods, thus paying off.
After one year of painstaking research, they designed and manufactured the integrated control panel for loom and completed the textile CAD/CAM program that can provide various patterns according to requirements and that can control the looms.
And with the establishment of the integrated production system, they shortened the period of developing new product within one hour instead of 6 months, to say nothing of the economy in raw material, quality of goods and good productivity.
A New X-Type Runner Developed
The research group headed by Mr. Han Song Ho, researcher of the Faculty of Mechanical Science & Technology developed a new x-type runner, thus making a great contribution to increasing the electric power in the hydraulic power stations.
Through their painstaking efforts of 10 years, they made an efficient decision of characteristics of inlet edge, blade section, blade head propel and outlet, by scientifically analyzing disadvantage of conventional runner, thereby developing a new x-type runner of which the hydraulic turbine has maximum efficiency over 2 % higher and work efficiency over 4% higher.
High-purity Hydrogen Generator Manufactured
The research group led by Jang Tae Il at Nano Physics Engineering Institute succeeded in manufacturing a high-purity hydrogen generator, from which high-purity hydrogen can be obtained by electrolysis with a solid macromolecular polyelectrolyte film.
They have developed nano catalyst material with high electrolysis efficiency and stability, and electrolysis technology of electrolyzing solid macromolecular polyelectrolyte film, which ensured high efficiency of energy conversion and high purity of hydrogen – 99.99%. At present they are making efforts to further raise the energy conversion efficiency, and to establish a distributed hydrogen energy system.
High efficiency waterproof agent developed
The research team led by Choe Song Il, director of Mirae Industrial Technology Institute, Ri Nam Chol, laboratory head of the Institute, developed high efficiency carboxylic acid system permeation crystal type concrete waterproof agent from their own technology and this is proving highly effective in green building materials industry.
This grey powdered waterproof agent is mixed with a certain amount of water and applied to concrete plastered wall and it yields waterproofing effects in two days. What’s of particular characteristics is its peculiar watertight quality that coexists with the lifespan of concrete. This agent permeates into concrete as deep as 100mm and develops needle crystals so that it forms a stable waterproof zone.
Various portable analyzers developed
Research team led by Kim Kum Chol, the laboratory head from the Faculty of Electronics, developed various high-efficiency portable analyzers with self-technology and is gaining public favors from various fields of national economy.
Colon bacilli analyzer developed by the research team analyzes colon bacilli in water, whose measurement range is 0~1 000/mL, minimum disjointing capability is 1/mL. Toxic gas analyzer analyzes CO, CO2, SO2, NO2, O3, H2S etc. in the air and its measurement range is 0~1 000ppm, minimum disjointing capability is 0.1ppm, analyzing time is less than 10s. The measurement range of procedure saltiness gauge used in the analysis of saltiness for underground ultra-salty water, soya and bean paste production process of basic foodstuff factories, saltiness of seawater, boiler feed water etc. is 0~30%, minimum disjointing capability is 0.1ppm. Of turbidity analyzer, measurement range is 0~10NTU and minimum disjointing capability is 0.1NTU. They are now developing their research work for further enhancing the accuracy of their analyzers.
Position Sensitive detector Developed
The research group including Pak Pyong Su, a head of lab the of Semiconductor Institute, developed entirely in our own way the position sensitive detector available for all kinds of precision devices such as an electronic scale, a range finding system, a bevel gauge, a vibrometer, and other displacement sensing elements and are now expanding its achievements.
The element has a non-linearity error of 0.1% and position sensitivity of 0.2 to 0.3㎛.
Animation Colouring Software Developed
Department head Kim Thae Song, lecturer Kim Myong Jun and their colleagues at Faculty of Information science and technology have developed a colour-mixing software for animation which enables the conformity of brightness, contrast, hue etc. of different types of video recorders and different time of filming. At the end of a year-long research, they succeeded in developing “Animation Coloring Software” of our own style, which has combined dozens of coloring functions including adjustment of colour range and hue, thus making a great contribution to the modernization of TV broadcast.
High-voltage Water Heater Developed
Head of lab, Jang Ki Ho and other researchers at Faculty of Heat Engineering have developed a high-voltage water heater of 1~3MW. The advantages of this over the conventional electric heating boiler and the boilers that use heavy oil, gas or coal include less consumption of electric power, less amount of space for installation, less initial investment and environmental friendliness. In particular, this heater serves as a major means to relieve the load shake in the generation of electricity by renewable energy.
A vigorous research of realizing Bio-cryptography System by means of fingerprints
A research team of Ri Su Chol, a head of Department of Faculty of Information Science and Technology was making a success in the research for realizing bio-cryptography system by means of fingerprints, a security system for managing safely licenses of users as well as fingerprints information and encryption keys on the basis of fingerprints information.
By doing so, they were able to resolve the problems of bio-information being stolen and used for attacking in bio-authentication system and have been making an effort to develop more efficient security means by combining organically data encryption with bio-authentication.
Build-up of the Information Service System of Forest Resources Management
A research team including Pak Chan Il, a head of lab of IT Institute and Ri Song Jun, a researcher developed the information service program of forest resources management that can make a contribution to restoration of forests and were building up its success.
This program makes it possible to restore forests in a scientific and planned way by mapping the damage of forests in real time owing to mountain fire, natural disaster and harmful insects and worms.
Loop Heat Pipe Solar Water Heater Developed and Introduced
The research group including Prof. Pak Yong Nam, head of department in the Faculty of Heat Engineering has developed loop heat pipe solar water heater and made further achievements.
This efficient solar product, which provides hot water of 50℃ even in winter, is available in several places including homes, hospitals, dining halls. It has advantage of high degree of heat efficiency, durability and the possibility of vertical and gradient installation. Its volume is 120L.
Brisk Research into Properties of High-speed Parallel Mechanisms being Conducted
Department head of Faculty of Mechanical Science and Technology Song Myong Sop and his research group have been intensifying their research into high-speed parallel robot in a brisk way to make further progress.
Last year after 3-year-long study, they finally succeeded in devising ball-joints and reduction gears, the most important parts of 3-DOF parallel robots, in conformity with the world trend, and they built all the components with domestically available material. They presented their success to the 70th founding anniversary of the university and now they are active in introducing it to several sectors of the national economy. The working space of this robot is 160mm in diameter.
Respiratory Capacity Measuring Device Developed
The research group led by Rim Jong Ho, department head of Faculty of Biology and Medicine Engineering, have developed a computer-combined respiratory capacity measuring device and are working to further improve its efficiency.
By strenuous efforts they chose a convenient-to-use measuring method and designed the structure uniquely. Besides they managed to find out reasonable constant values that are suitable for the physical features of the children in our country and for making correct judgment of their physiological functions. Then they combined the device and a computer so that the measuring process can be monitored in real-time. Thus, they were able to obtain respiration curves through the flow measurement of the respiratory process of human body and on the basis of this they determined tens of test indexes for respiratory capacity that can accurately assess the functions of lungs such as maximum expiratory capacity, one-round breathing capacity and maximum inspiratory capacity, thereby ensuring scientific diagnosis of respiratory diseases thoroughly relying on domestic equipment.
Since introduced in a hospital it has gained public favor for its convenience. It’s also being applied to education practice of several major subjects like “Biomedical information Processing”, “Digital Signal Processing”, “Neural Network” and so on.
Gamma Spectrum Analyzer Developed
Choe Pyong Min, Vice Dean for Scientific Research of Faculty of Resources Probing Engineering, and his research group have developed our own type of gamma spectrum analyzer which is of great significance in exploration of minerals, and have been expanding their successes.
After 3 years of painstaking efforts they developed a four-channel portable gamma spectrum analyzer that makes it possible to analyze the content of elements in mineral rocks directly on the spot without extracting samples from them. Subsequently they succeeded in a gamma spectrum analyzer with higher accuracy and higher temperature stability. Not content with their achievements they are making constant efforts to further raise its analysis accuracy.
Stepping up with introduction of the laser vibrating meter
A research group of Kim Chol Hyon, a teacher of Faculty of Physics Engineering succeeded in developing the laser vibrating meter which can measure the number of vibration of micro-vibrating things as well as the width of vibration by dividing them into tens of nanometers so as to add successes to different aspects of the national economy.
Development of the technology of measuring the 3-dimension outline by means of laser
A research group of head of the Physics Engineering Faculty developed the technology for measuring precisely the 3 dimension outline of the thing by means of the injection of the straight line laser and processing the value of co-ordinates with the computer so that they could make a great contribution to different aspects of the light industry and public healthcare and physics culture including clothing and shoes industry.
They devised the precise micro-vibrating apparatus which can inject the outline of the thing with the straight line laser and detect its light lines and also developed the 3-dimension producing program to get more correct outline of the thing. At present this research group is channeling a great effort to improving the accuracy of this technology.
Development of the gas-detecting transmitter and application technology of micro-bubble
The research team including Jang Chol Min, head of laboratory of Nano Physics Engineering Institute developed the gas-detecting transmitter and application technology of micro-bubble, and are building on its success.
They succeeded in developing the gas-detecting material which is capable of detecting quickly and precisely ammonia, hydrogen sulfide and carbon dioxide in the air and on the basis of this, they also developed the automatic gas-detecting transmitter which is capable of measuring and controlling the gas in the given building in real time by manufacturing the solid-state detector which has higher adaptability to environment, lasts longer and is much cheaper than an electrical and chemical way.
They also introduced the micro-bubble technology into purification of waste water so that they could speed up the disintegration of aerobic microorganism into organic materials, and created the reliable technical guarantee for discharging purified water by establishing the process of purifying waste water bio-chemically which can improve the average characteristic indices of water quality such as biochemical and chemical requirement for oxygen and ratio of removing ammonia nitrogen in comparison with the general porous plant by 10 or 20 % and decrease the consumption of electric power to less than 80 % by means of oxidization of organic polluting material which are impossible to decompose with radical ions generating micro-bubbles.
As a result of introduction in one stock-farm, this technology proved very efficient and economic.
In the future, fruitful will be their continuous research for applying it to various fields including purification of water as well as production of crops and vegetables, aquatic culture, IC cleansing, floriculture and preservation of freshness of fishes.
New grounding resistance electrometer
The research group led by Choe Ji Myong, the head of a laboratory in the Faculty of Electronics Engineering, developed a new grounding resistance electrometer that can measure the grounding resistance of the power electronic system with the correctness of below ±0.1Ω, opening up the broad prospect of preventing the destruction of electric and electronic products and ensuring the safe management by designing and manufacturing with their own efforts the devices with the automatic switching function on a measuring zone of 0.1~1kΩ. Now, the group is continuously pushing forward the research project to develop the wireless power transmitting system.
Establishment of the New Hot Blast Drying Process for CMYK Offset Duplicator
Pak Se Il and his research team of the Faculty of Heat Engineering succeeded in establishing the hot blast drying process for CMYK which is using electrically heated air.
They proposed to use electrically heated air instead of propane gas to dry the printing material in the CMYK hot blast offset duplicator and made clear the characteristics of drying printing material and the relationship of different elements which have influence on the quality and output of products and consumption of electricity of the printing material while they are dried. They also designed the new heat switchboard which is capable of making an effective use of the heat of waste air at different temperatures of more than 110℃ giving off during the period of drying so that they could economize a large amount of energy needed in drying the printing material.
They constructed the control system in keeping with the operation conditions so that rational indices of the operation were determined which made it possible to establish the hot blast drying process using electrically heated air.
New Magnesia Cement Developed
Ra Chung Yol and Cho Yong Yon, researchers from the Faculty of Resources Probing Engineering have developed white magnesia cement, green building material, from our own brucite marble, and greatly contributed to the industrialization.
Newly developed white magnesia cement can be produced in the existing process in the factory without establishing a new process and its pressure strength is 42MPa. As the burning temperature is 100~200℃ lower in comparison with dolomitecement and the range is between 400℃ and 700℃, it consumes less fuel andconvenient to produce. In particular the whiteness is over 88%, so it is far superior to another magnesia cement. Therefore, it is being used as good finishing building materials.
Research on Tiezo Resistive Differential Pressure Tranducer Activated
The research group in the Semiconductor Institute including Rim Chang Sik, Ri Won U has made a great achievement in the researchwork to develop the differential pressure transducer necessary for measuring the fluid amount.
This project is the tiezo resistive differential pressure transducer which measures the high-temperature steam fluid in the thermal power station and the flowing amount of fluid with high pressure and temperature in the chemical industry.
The research group selected a lot of materials appropriate to different differential pressure forming modes, reliable in high pressure and temperature and sensitive to the variation of pressure and designed and trialed while precisely changing the shape and structure of the diaphragm, thereby solving many scientific and technological problems such as the material and structure of the diaphragm, the manufacture, and the placement of the diaphragm, and the sensitivity and the precision. By doing so, they have opened a bright prospect of developing with our own technology the differential pressure measuring device which is cheap and has great precision of 1%FS in measuring the pressure difference of various bands from 1 to 50KPa
Cubic Structure Attitude Control Experimental Instrument Developed
Li Gyong Il, lecturer of the Faculty of Automation Engineering has developed a cubic structure attitude control experimental instrument.
Though in need of reference data, he mathematically modeled the geometrical size, material selection, centre of mass of each part and inertial moment to develop a system of attitude stabilization control system and confirmed the reliability of the instrument through scores of simulations and linkage experiments. The cubic structure attitude control experimental instrument he developed is a valuable one not only for the students’ experiment but also for checking up the efficiency of the attitude control algorithm used in the ultra-miniature equipment.
Not satisfied with his result, he keeps making a profound research to develop the attitude stabilization control system with jump-up and corner as a fulcrum.
Wireless Elastic Wave Measuring Instrument developed
Kim Il Hyok, lecturer of the Faculty of Resources Probing Engineering, has developed the wireless elastic wave measuring instrument which is widely used in practice.
This instrument is used to rationally determine the covering layer of a waterway tunnel by measuring the strength of the bedrock. Newly developed elastic wave measuring instrument is composed in the form of radio system and graph display and sensors are installed so as to serve as a measuring duster in any position without confusion. Therefore it is very fast and measuring work is done conveniently and the best thing about this instrument is that it has no telegraphic interruption and noise.