Jo Jan 20, 2024
Statistical data mixed with qualitative and quantitative indices are usually prepared for object identification. In the medical field, qualitative indices such as pathological complaints and quantitative indices such as laboratory tests are often given together, so it is very important to make a discriminant for diagnosing a patient’s disease properly.
To date, no method has been developed to produce a discriminant in the presence of both qualitative and quantitative indices.
Kim Ju Hyong, a researcher at the Faculty of Biology and Medicine Engineering, has proposed a new method of object identification from statistical data with both qualitative and quantitative indices.
He has applied the method to diagnosis of hundreds of diseases ―cerebral apoplexy, autonomic imbalance, carcinoma in stomach, liver, colon, lungs, women and nose, acute abdomen symptoms, cardiopathy, cryptogenic gangrene, caput external stroke, etc.
The results confirmed that his method has high possibility of producing a more reasonable discriminant by performing iterative calculations considering the degree to which qualitative and quantitative indices contribute to the discrimination, and that it is a simple and widely used method for diagnosis of medical diseases from both indices.
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Jo Jan 18, 2024
NTC (Negative Temperature Coefficient) thermistor is widely used in industrial application for temperature measurement, control and compensation. The important problem in using NTC thermistor is to overcome its aging phenomenon.
Yu Nam Chol, a researcher at the Science Engineering Institute, has prepared Fe0.8Mn1.54Ni0.66O4 NTC material by the more convenient nitrate decomposition method, investigated the electrical properties of thermistors sintered at different temperature ranges, and determined the reasonable temperature and time and the effect of N2 annealing atmosphere on the aging behavior.
Observation of the microstructure and phase of this material indicated that it has compact and uniform spinel structure. He also found that the sample sintered at 1 200℃ was suitable for building a thermistor and that the aging behavior drops below 0.7% when it is under N2 heat-treating for 72 hours around 450-550℃.
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Jo Jan 17, 2024
Display of works of art such as color photos needs two competing criteria: appearance and color degradation. The more the blue radiant flux of pc-white LED lamps increases, the more color degradation occurs. However, previous studies have focused on the improvement of color rendering property and luminous efficacy, and decreasing the ratio of blue radiant flux while maintaining the needed color rendering property and luminous efficacy has been hardly discussed.
Kim Ju Yong, a researcher at the Faculty of Electronics, has investigated the effect of correlated color temperature (CCT) and spectral power distribution (SPD) of PC-white LED lamps on the color degradation of color samples and the difference between the decolorizing reduction of color samples and that of textiles dyed with natural dyes.
Controlling the SPD by combining the blue LED chip and G-O-R phosphors, he manufactured a test lamp with high color rendering property. The high color rendering property and small blue peak radiant flux of the test lamps lead to the best effect on color appearance and decolorizing reduction.
After color samples for color pictures were decolorized with accelerating degradation method, the color degradation caused by test lamp (TL) was about a half of that of comparison test LED lamp (CL). The test results showed that for the pc-white LED lamps, the decolorizing reduction effect depends on SPD more than CCT.
He also proved that unlike the textiles dyed with natural dyes, green and violet were decolorized most, followed by yellow from samples for color pictures.
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Jo Jan 15, 2024
In recent years, fractional calculus has been applied in the modeling and control of various kinds of physical systems, as well known and documented in many control theories or in application literature.
In fact, the design of feedback controllers for fractional order systems (FOS) has been approached from generalizations of some classical design methods. For example, the fractional order PID controller can be seen as generalization of a traditional PID controller.
Various engineers designed fractional PID controllers using different designs and tuning methods. However, tuning of a fractional PID controller is a challenging work, because there are five parameters to tune, which means two more parameters than a classical PID controller.
So, Hyon Chung Il, a section head at the Faculty of Automation Engineering, has proposed a design method of a fractional order [proportional derivative] controller for a type of fractional order systems, and verified its effectiveness through comparisons with other controllers such as the traditional integer order PID controller and the fractional order proportional derivative controller.
The comparisons illustrate that the IO-PID controller designed may not always be stable enough to achieve the iso-damping specification and that the proposed FO-[PD] controller outperforms FO-PD controllers.
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Jo Jan 13, 2024
Air flow measurement is an important task in many fields including process control, air conditioning systems, environmental monitoring, medical instrumentation, weather forecasting system and so forth. For many years, flow sensing was accomplished by means of large-scale mechanical flow meters such as anemometers, turbines and Pitot tubes. In recent years, many researchers have applied micromachining processes to realizing micro sensors and arrays for measuring air flow parameters. Many previous studies have demonstrated successful application of micro electro-mechanical system (MEMS) techniques to the fabrication of variety of flow sensors capable of detecting both flow rate and flow direction.
MEMS-based sensors have advantages of small size and light weight. They can briefly be divided into two categories: mechanical sensors and thermal sensors.
Recently, multi-sensor integrated technology has become fashionable in the sensor domain. This sensor shows the merits of both a drag force flow sensor and a thermal flow sensor by integrating them to obtain high sensitivity over a wide range. Although it is sensitive to both low and high rate, it has both mechanical and thermal parts.
Rim Chang Sik, a researcher at the Semiconductor Institute, has proposed a cantilever-based air flow sensor for measuring flow-rate and flow-direction simultaneously using only a mechanical part without a thermal one.
The sensing device is comprised of a standing cylinder-cantilever and an MEMS-based silicon diaphragm with eight diffused piezoresistors as sensing elements.
The device is effective to exactly determine air flow direction angle and to expand operation range with relatively simple structure.
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Jo Jan 11, 2024
The idea of using both gain and phase in robust control theory was proposed and studied by several researchers in 1980s. Especially, the robust control theory based on gain-phase information (GP robust control theory), which started to be studied in 1999 produced new concepts like Ψ-control, H∞/Ψ-control and GP mixed sensitivity control and opened up a new stage for development of robust control theory.
However, all the researches considered only Single Input Single Output (SISO) system. So, it is very important to find a solution to the Ψ-control problem for Multi Input Multi Output (MIMO) system.
Pak Kwang Hae, a researcher at the Faculty of Automation Engineering, has proposed a new solution to Ψ-control problem for SISO system and laid methodological foundations for finding a solution for MIMO system.
To verify the efficiency and applicable possibility of the designed control system, he newly designed an automotive fuel control system and compared it with previous methods through computer simulations.
The results proved that the proposed method is effective and available in practice.
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