Jo Aug 23, 2023
A research team led by Kang Song Il, a researcher at the Faculty of Mining Engineering, has developed a load cell capable of precisely measuring mechanical properties of coal faces in full consideration of the effect of eccentric load in order to explain ground pressure characteristics.
The load cell consists of an elastic body and a resistance wire sensor.
The elastic body consists of four beams whose two sides are fixed and each beam has two resistance wire sensors on both sides. A total of 16 resistance wire sensors form a bridge circuit.
As four resistance wire sensors are connected in series on each branch of the bridge circuit, different deformations generated from them do not affect the overall measurement results. Instead, only total resistance change generated on the four resistance wire sensors is related to the measurement results.
The load on the elastic body is represented as the change of the sensor as it is transferred to the resistance wire sensor. Resistance values are calculated from the relationship between the resistance and the change, and displayed as resistance values in the multi-channel measuring device.
The load cell is installed in the support of a coal face. Vertical load is measured by a ground pressure meter between a beam and a middle support, which is set up in the middle of a beam of the support, while side load is measured by the meter in a lagging, which is set up between a coal wall and a bridge of the support.
The ground pressure characteristics in an area can be figured out by the properties of a certain area obtained in a mathematical method from measured values and the properties of known areas.
This device is helpful to get a correct description of ground pressure characteristics found in all kinds of coal mines and faces in different geological conditions, and to measure precisely the mechanical properties of corresponding rock mass such as cohesion, angle of internal friction and Poisson coefficient, which makes it possible to establish suitable methods of supporting mines. It will lead to a significant reduction in the consumption of materials such as supports, and safe working conditions and stability of coal production.
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Jo Aug 21, 2023
A research team led by Kim Haeng Sok, a researcher at the Faculty of Electrical Engineering, has developed a partial discharge measurement system for insulation condition estimation in electrical power equipment.
Measurement of partial discharges (PD) is an effective way to evaluate insulating material degradation in high voltage equipment.
Partial discharge promotes degradation of insulating material and extends discharge paths to destroy insulation.
The partial discharge measurement system consists of a pulse current sensor, a measurement device and a display device. Partial discharge signals are transferred to the measurement device via a pulse current sensor, and after noise detection and correction, they are described as the amount of discharge to evaluate the state of insulation. A ferrite core is used for the pulse current sensor and the measurement device is aimed at filtering, amplifying and processing the signals.
The research team decided structural parameters of the pulse current sensor and detected the PD signals involved in noise by processing wavelet signals.
The system provides possibility to prevent hazards of high voltage equipment by evaluating in real time the state of insulation for any kind of electric power equipment. It can be widely adapted in the fields of electrical power industry.
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Jo Aug 18, 2023
A research team led by Pak In Hui, a researcher at the Faculty of Biology and Medicine Engineering, has developed an electrical stimulator combined with low-frequency and medium-wave heat. It is a modern computer-controlled medical device of our own style in which optimization and digitization are fully realized.
The stimulator consists of a body, an RS-232C data transmission bus, a computer therapy control program, and therapeutic conductors. The body is divided into three parts: diagnosis, therapy and display.
The therapeutic conductors include a massage stimulator to relieve the tension of visceral organs and muscles and improve blood circulation, a roll needle stimulator capable of self-searching and stimulating various treatment points, and a device for treating diseases using a midwave tunnel effect.
They determined the optimal stimulus parameters for appropriate frequency, intensity, time and method to accurately detect and measure light blood reaction points on the skin surface and to treat diseases and dysfunctions.
When diseases destroy the homeostasis of human body, the stimulator can effectively treat them by giving frequency and midwave tunnel stimulus to the corresponding acupuncture points. It is particularly effective for digestive and urinogenital diseases.
This device can automatically control all treatment processes by computer therapy control programs according to diseases and patient’s conditions, and it can save many drugs as it provides non-infestation therapy. Thus, it will enjoy wide application in the field of public healthcare.
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Jo Aug 17, 2023
A research team led by Kim Pyong Hun, a section head at the General Assay Office, has developed a device for rapidly determining the concentration of biochemical indexes in human blood and other body fluids by spectrophotometric method.
The automated biochemistry analyzer is a medical analytical instrument for diagnosing several kinds of diseases by rapidly determining the concentration of biochemical indexes of blood and other body fluids such as GOT, GPT, TP, CK, GLU, LDH, etc.
It consists of sample injection unit, regeants injection unit, reaction and optical monochromator unit, stirring unit, washing unit, power supply unit, control unit, etc.
In the sample injection unit, the range of sample setting volume is 1 to 20μL with 0.1μL stepping. The sample disk has a total of 120 positions. The sample probe works above the reaction cuvette, and then returns to the sample probe rinse trough.
In the regeants injection unit, the range of reagent setting volume is 10 to 400μL with 1μL stepping. The reagent disk has 80 positions in total. The reagent probe works in the same way as the sample probe. Reagent bottle volumes are 15ml, 20ml, 70ml, etc.
In the reaction and optical monochromator unit, reaction cuvette volume is about 150～500μL. The range of wavelength in the photometric system is 340～750nm. The wavelength accuracy is ±2nm. The light source is a 20W/12V life quartz halogen lamp. The measurement range is 0 to 4Abs. The incubation bath temperature is 37±0.1℃. The reaction disk has 80 positions in all.
In the stirring unit, stirring is carried out after addition of sample and reagent each. After stirring, the stirring rod comes back to the rinse trough.
In the washing unit, the reaction cuvettes are washed after measurement.
In the reagent cooling unit, all reagents are kept at 5~15℃.
In the power supply unit, power is supplied to the signal amplifier and controller as well as to the probe for injecting liquor necessary for sample injection, reagent injection, washing, etc. and to the switching valves for selecting liquor.
The analysis methods include rate assay, end-point assay and 2-point assay. The calibration methods include 1-point linearity, 2-point linearity, multi-point linearity and non-linearity.
The automated biochemistry analyzer is applicable to the following indexes: GOT 35.4~56.3u/L, GPT 25.6~42.3u/L, TP 4.54~5.66mg/dL, CK 115~173u/L, GLU 76.4~106mg/dL, ALB 2.54~4.06mg/dL, LDH 152~214u/L, etc.
The accuracy of the analyzer is ≤1.5% for biochemical indexes.
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Jo Aug 16, 2023
The loupe developed by a research team led by Kang Thae Hyok, a researcher at the Faculty of Mechanical Science and Technology, is a portable optical instrument for successful performance of microsurgical operations.
This instrument can be used to raise the accuracy of performing operations by magnifying internal structure of eyes invisible to the naked eye.
It is made up of an optical unit, an illumination unit, a control unit and a glasses frame.
The optical unit is composed of two binocular tubes. Its magnification is 3X, the working distance is 250~300mm and the field of view is 40mm.
1W/3V LED is used for illumination.
The control unit is a device to adjust the distance of axes of the two tubes to the space between eyes. The rack pinion installed in the control body adjusts the space within 50~75mm by the knob.
They established the optimum optical system for convenience and accuracy of operations and solved technological problems arising in the minimization of the size of the instrument.
The loupe they have developed will find wide application in observation of fine structures and micromanipulation as well as in clinical practices like operations on eyes and blood vessels.
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Jo Aug 14, 2023
A research team led by Won Ju, a researcher at the Nano Physics Engineering Institute, has developed an effective reflector for microwave leakage prevention.
When applied to organisms, microwave changes the potential and charge on both sides of the cell membrane, thus impairing its function, destroying normal metabolic and physiological activities of the cell, and changing the quality of physiologically active substances. All these result in drying and sterilization of microorganisms.
Microwave is absorbed in large quantities into dielectrics such as wood and plastic or water-containing materials, but it is reflected on metal surfaces. When microwave is reflected from material, the material cannot be heated. Instead, the material is heated only by absorbing the energy of the microwave. It means that leakage of microwave leads to low efficiency of microwave equipment.
The reflector for preventing microwave leakage consists of a cuboid structure (except for two sides of the inlet and outlet) whose c-shaped reflective elements are arranged at regular intervals in columns in an indented way.
The width-depth-height ratio (a:b:c) in the reflector is 3:2.5:1.
When the microwave propagated inside the microwave device enters into the input/output channel region, it is reflected by the reflective elements so that the microwave does not come out but returns inside, which leads to significant reduction in the leakage of microwave.
He proposed a geometric structure of a leak suppressor that can effectively prevent microwave leakage in a microwave drying sterilizer, and carried out a simulation on microwave propagation inside the suppressor so as to determine its dimension and position.
As a result, the efficiency of a microwave drying sterilizer was improved and at the same time, production efficiency and quality of products were improved with less power.
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