Jo Mar 19, 2023
A research team led by Kim Myong Il, a section head at the Faculty of Mechanical Science and Technology, has designed a CNC hobbing machine for dry and wet cutting by high-speed tools or carbide cutting tools, in consideration of future development in the field of cutting tools.
This machine consists of a machine body, a control panel, a control cabinet, a cooling and chip removal device, an oil pump, etc. It is designed for handsome appearance, in conformity with human-machine engineering demand, and for convinience of machining, maintenance and material conveying.
With 6 control axes and 4 simultanous axes, it can cut spur gears, bevel gears, worm wheels and non-circular gears such as elliptic gears.
The technical characteristics of the machine are as follows.
Maximum work piece diameter: 500mm
Modulus range of gear machining: 1.5~6
This machine has remarkably upgraded machining accuracy and productivity and is good for environmental protection.
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Jo Mar 17, 2023
Measurement of low concentration oxygen gas is very important in chemical processes where several kinds of material gas and fuel gas are used. If the concentration of combustible oxygen gas gets high, it might cause explosion, which will have vicious influence upon the whole process. So, real-time measurement of oxygen at low concentration is essential for taking proper measures.
Two common techniques for sensing oxygen at low concentration are luminescent optical sensing and electrochemical sensing. Both demonstrate high sensitivity to low concentration oxygen. Fluorescent oxygen sensing has seen widespread adoption thanks to its inherent stability. However, application of this technique is limited due to complicated fabrication and short life time. On the other hand, electrochemical sensors are widely used and available in different forms according to the demands of users.
A research team led by Choe Chol Man, an institute head at the Faculty of Electronics, made an amperometric oxygen sensor based on the electrochemical method to manufacture an oxygen concentration measuring instrument, and introduced a refrigerator and a gas cleaning instrument for removing the effect of interference elements, thus completing a system of measuring low concentration oxygen gas.
The left picture shows the construction of the oxygen sensor incorporating a cathode, an anode, an electrolyte solution and a gas permeable membrane, all of which affect the characteristics of the sensor. They used silver with good oxygen reduction characteristics as a cathode, and silver/silver chloride electrode as an anode. KCl saturation solution and PTFE thin film were selected as an electrolyte and a gas permeable membrane, respectively.
They introduced digital signal processing technology to remove atmospheric noises so that the instrument could work properly in any operation environment, thus ensuring the stability and reliability of the instrument. The right picture shows the installation of the system.
The specification of the system is as follows.
Measurable band: 0~10%
Response time: 30s
Accuracy: 0.1%
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Jo Mar 16, 2023
People in Koryo produced high-quality paper by carrying forward the long paper-making tradition of the Three Kingdoms (Koguryo, Paekje and Silla).
The general features of a variety of Koryo paper were whiteness, durability, smoothness, softness and freedom from fuzz and moth.
In those days, Koryo paper was widely known abroad for its excellent quality.
In particular, paekmunji (white paper for official documents), kyonji (highly durable paper) and achongji (dark blue paper) were exported to China during Koryo and feudal Joson dynasties and they were owned as necessities by aristocrats in that country.
“Korean bibliography” published in Paris, France, in 1894 gives a detailed description of the excellence of Koryo paper.
“All the paper used for Korean books, no matter which era it was from, is soft and tough, so even old books in fairly thin paper have endured for a very long time. It is demonstrated by the fact that Koryo books found in temples or European libraries are not at all tinted with yellow nor moth-eaten. It is not known when paper industry was established in Korea. However, paper must have been made in Korea from ancient times, which is strongly supported by the following facts ― nothing but paper was used for writing; books were already in wide circulation and there was a well-organized research institute in the ninth century; libraries were instituted in the next century (tenth century).
Invented by the resourcefulness and talent of our people, Koryo paper was renowned as the first on earth for its excellence.
Kim Kwang Jo, researcher at the Academy of Social Sciences
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Jo Mar 14, 2023
A research team led by Kim Thae Ung, a section head at the Faculty of Automation Engineering, has established an integrated automation system of the ore dressing process for the production of apatite concentrate.
The system supports comprehensive monitoring and operation of a whole process by displaying process data including the information of operation state of motors in crushing processes, grinding processes and flotation processes, pulp density, flotation temperature, pH value, amount of reagent consumption and level of industrial water numerically and graphically. It saves data of process variables of the subprocesses in the corresponding data base.
The process interface consists of process monitoring, grinding process, flotation process, reagent supplier, operation mode and process history.
The system shows several advantages. The ore dressing recovery and the concentrate grade are guaranteed at over 80% and 30% respectively. The reagent consumption is reduced by more than 10% and the labor is economized by 15%.
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Jo Mar 13, 2023
Sol Kyong Song (1237－1313), a doctor in Koryo, learnt medicine from his early age. When he became a doctor, he put his heart and soul into treatment and medical research.
He was well known at home and abroad as he was well versed in Koryo’s advanced clinical medicine of that time and excellent at treatment.
In 1285, he was invited to a neighbouring country to cure the king of the country from the disease that was accepted as incurable by many doctors invited there, thus showing the high standard of medical development of Koryo. After that, he was invited to the country several times more and demonstrated his excellent medical art.
Although he was in a favour with the King, Sol Kyong Song never wanted him to bestow any special benefits upon himself and what is more, he was indifferent to the living of his family. Instead, he devoted his all to treatment of patients and medical research to the last minute of his life.
Along with Ri Sang Ro, who lived in the second half of the twelfth century, Sol Kyong Song was known as one of the two great doctors of Koryo.
Sin Kwang Il, researcher at the Academy of Social Sciences
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Jo Mar 10, 2023
Jang Rim Chol, a researcher at the Faculty of Mechanical Science and Technology, has developed a CNC engraving machine for cutting an EPS model.
The machine ensures high geometric accuracy and surface finish in cutting EPS models for lost form casting.
It consists of a computer, a control device, a mechanical system, an exhaust fan, etc.
What is new about it is the development of a spindle unit for EPS cutting and a rolling guide using ball bearings. Also, it has a rotary table that can change its rotating axis vertically and horizontally, so the machine offers satisfactory cutting of the EPS model of a spur gear whose diameter is 2 meters. The machine is also applicable to complex and large EPS models such as large bevel gears, housings and manikins.
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