Jo Dec 9, 2025
Currently, research on parameter tuning methods is active due to the widespread use of PID controllers in industrial practice. Many studies have been carried out on self-tuning methods to tune the parameters of PID controllers with varying plant parameters, bringing about remarkable successes.
Meanwhile, the Particle Swarm Optimization (PSO) algorithm is a kind of optimization method based on the theory of cluster intelligence, which has been widely applied in the field of function optimization, neural network learning, multiobjective optimization, fuzzy control system, etc. The population optimization algorithm is easily applicable to various types of problems because there are no complex crossover and mutation operations like in genetic algorithms. The greatest advantage of PSO algorithm is its fast convergence speed, simplicity of evolution operation, low computational cost and small number of parameters used in it.
The T-S fuzzy model approximates nonlinear characteristics, and inference using it can be used as a tool to implement controllers or fuzzy models with optimal and adaptive functions because it is simple and convenient for mathematical analysis and it can be easily combined with PID control or adaptive control.
Kim Yong Su, a researcher at the Faculty of Automatics, has proposed a method for designing a PID controller, based on the characteristics of PSO algorithm and T-S fuzzy model.
According to the proposed method, you first use the PSO algorithm to determine the position of a dominant pole which minimizes the judge function consisting of Integral of Absolute Error (IAE) and overshoot value and then express it as a T-S fuzzy model to determine the parameters of a PID controller using fuzzy inference.
The proposed method allows you to get both the optimal dominant pole and the exchanging frequency at the same time, and to get a good control result as the overshoot value is small.
...
Jo Dec 6, 2025
Our country was well known to the world as a land of silk fabrics from olden times.
According to the records, the Korean ancestors started to acclimatize undomesticated silkworms to raise mulberry silkworms in olden times, and they obtained raw silk from silkworms to weave fabrics for clothing in the ancient times.
In the period of the Three Kingdoms, silkworm culture further flourished and their high-level weaving techniques led to the production of several kinds of high-grade silk fabrics with beautiful and colourful patterns to be sold to the neighboring countries.
Korean silk fabrics were accepted to be far superior to those of other countries in terms of quiet sheen, smooth touch and delicacy and even more expensive than gold. In the period of Koryo, they were exported to the far Arabian peninsula as well as to the neighbouring countries, gaining fame as the best on earth.
The main feature of the Korean silk distinguished from those of neighbouring countries was not to boil cocoons enough and not to completely remove sericin when reeling raw silk off them.
The fabric woven from such silk was not too loose but a little stiff like starched and felt fresh and fine.
The Korean ancestors were also the first to devise dye printing for silk cloth.
As mentioned above, the Korean nation is a resourceful and civilized nation which created and developed the silk culture admired by the world people a long time ago.
...
Jo Dec 5, 2025
Recent rapid development of mobile devices such as tablets and smartphones makes it possible to take a university course anywhere anytime and it has brought about a new type of learning; m-learning.
Downloading has been a common method for mobility. However, it is inevitable to download all data even when you need a certain part of a video clip or when you just need to go through it. This wastes communication cost and requires a user to wait until downloading is completed. In addition, it needs space for storing the downloaded data. Thus, streaming service of mobile education is a breakthrough in the world of education as a means of learning using Internet technology and mobile telecommunications devices.
Ri Ye Bok, a researcher at the Faculty of On-line Education, has proposed a SCORM-based package model for streaming service in distance education through mobile network.
The proposed model enables two kinds of service—downloading and streaming, using the same contents, thus not only guaranteeing the safety of data, but also saving memory space and providing convenience of management.
It can be easily implemented on various distance education sites as it converts learning contents into those for Android-based devices to provide several kinds of service in distance education systems based on the SCORM standard model.
...
Jo Dec 2, 2025
Chonsangryolchabunyajido is an astronomical chart made in the late fourteenth century.
It dates back to 1395, based on the Koguryo’s astronomical chart carved on a stone.
The Koguryo’s astronomical chart (a table of constellations carved on a stone of about 2 meters in length and 1.2 meters in width) made between the late fifth century and the early sixth century shows 1 467 stars that were visible in the night sky of Pyongyang at that time. They are categorized in 282 constellations in a circle. The black ink copy of them on a piece of paper was used as base data for astronomical observation and calendar compilation.
Chonsangryolchabunyajido (122.8cm wide and 209.9cm long) was considered a very scientific and accurate astronomical chart in those days.
As one of the precious cultural legacies demonstrating the astronomical development of our country in the middle ages, it provides valuable information for the study of astronomical history.
...
Jo Nov 28, 2025
Terbium belongs to the lanthanide or “rare earth elements (REE)” group of elements in the periodic table. However, rare earth elements are dispersed and they are not generally found concentrated as rare earth minerals (REM) in economically exploitable ore deposits. Terbium only occurs in trace quantities even in its ores. It is found in some minerals such as bastnaesite, monazite, xenotime, euxenite and gadolinite ores, but in low concentrations, on the order of 1%.
Terbium and its compounds are used as phosphors. Terbium phosphors give off a green light when struck by electrons. Phosphorescent terbium compounds are used in cathode ray tubes, light-emitting diodes, lasers, sensors, etc. Thus, terbium extraction processes need to be further studied and improved to include more economical and profitable methods.
Choe Kyong Mun, a researcher at the General Assay Office, has investigated the electrochemical behaviors of terbium in TbCl3-1-ethyl-3-methyl-imidazolium tetrafluoroborate [EMIm]BF4 electrolytes and TbCl3-1-ethyl-3-methyl-imidazolium dicyanamide [EMIm]DCA.
X-ray diffraction analysis results of electrodeposits from TbCl3-[EMIm]BF4 electrolytes and TbCl3-[EMIm]DCA electrolyte prove that metallic terbium is obtained.
For more information, please refer to his paper “Electrochemical behaviors of terbium from TbCl3-EMImBF4 and TbCl3-EMImDCA ionic liquid electrolytes: a comparative study” in “Journal of Solid State Electrochemistry” (SCI).
...
Jo Nov 27, 2025
A protective relay plays a crucial role in the normal operation of a power system and the reliable supply of electrical power. The reliable operation of an electrical power transformer is very important in maintaining uninterrupted power supply. In a protective scheme for a transformer, high speed of protection and reliable operation against clear faults are essential.
Many advanced algorithms for power system protection have been implemented on the relay protection devices based on microprocessors in programming form. To be candid, there are no references showing the results related to the design and implementation of a multi-function protective relay for a power transformer.
Im Jung Bin, a researcher at the Faculty of Electrical Engineering, has proposed a method for implementing a modularized multi-functional hardware transformer protective relay based on Field programmable gate array (FPGA) for higher speed operation of protection.
Taking the advantage of parallelism feature of FPGA, the proposed hardware transformer relay can process multi-channel input signals at high speed in real time, and concurrently estimate and process protective logics with different functions. By using a single Altera CycloneⅢ EP3C40Q240CN8 and configuring different-function protective relays, this relay allows high-speed operation which is a basic demand for protection.
This relay can operate within 1.1 cycle of power frequency.
You can find details in his paper “A Structure of Transformer Protective Relay for Implementing a High-speed Operation of Many Protective Functions Using a Parallel Processing Feature of FPGA” in “Journal of Electrical Power & Energy Systems” (EI).
...