Jo Jan 7, 2026
The games for training martial arts in the period of Koryo included archery, fencing, spearing, horse-riding, Subak, ssirum, stone-throwing, running, etc.
These games reflecting the martial spirit of Koguryo were the improvement of the ways of playing and competition of those days.
During the Koryo dynasty, many archery grounds were built and game rules were made so that warriors and archery beginners could practise archery and have a match, and awarding ceremonies for them took place.
Horse riding developed, too. High riding skills like riding into and out of the fire as well as performing various tricks on the horseback were displayed in this period.
Subak of those days which was a combination of fistic fighting with kicking and heading was very powerful. The fact that there was a military unit specialized in Subak and national Subak matches were widely organized suggests that Subak was more popular than ever before.
In Koryo, ssirum was selected as an important martial art and ssirum games were held at every opportunity.
How much ssirum was encouraged and popular in those days is well explained by the fact that a Koryo king watched ssirum matches with warriors.
The strenuous effort of Koryo people to train martial arts including stone-throwing and running brought brilliant fruitions in anti-aggression wars for defending the sovereignty of the country and the dignity of the nation, and led to the great feats demonstrating the spirit of the Korean nation thereafter.
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Jo Jan 6, 2026
Line-start permanent magnet synchronous motor (LSPMSM) is a self-starting PMSM, which features both induction motor and conventional synchronous motor. The asynchronous torque generated by the stator-rotating magnetic field and its interaction with the squirrel cage rotor drives this motor. In normal operation, the rotor is driven at synchronous speed and the cage rotor is not actuated. Its operating principle is the same as that of a conventional synchronous motor. What is different is that the PMSM provides a permanent magnet (PM) with a magnetic field necessary for energy conversion, so it is simple in configuration and significantly high in energy density.
With the efficiency and power factor higher than induction motors, LSPMSMs have found wide application in various fields such as light industry, textile industry, oil industry, chemical industry and transportation. In particular, they have incomparable advantages over induction motors in respect of fans, compressors, pumps, etc. Therefore, there is a world trend to replace induction motors with them as they are stable in rotational speed and have high efficiency and power factor.
Many researchers have studied the starting, synchronizing and efficiency enhancement of LSPMSM and investigated the influence of various parameters. There is no research data available that detailed the rotor configuration, design method and manufacturing method for the induction motor to be modified to LSPMSM.
Ki Yong Chol, a researcher at the Faculty of Electrical Engineering, proposed a rotor configuration scheme to convert a three-phase low-power induction motor into LSPMSM, carried out the optimal design of the rotor, and simulated the motor characteristics under different operating conditions.
To verify the simulation results, he built a prototype and conducted a test. The test results were in good agreement with the simulation results, showing that the efficiency and power factor increased as compared with conventional induction motors.
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Jo Jan 3, 2026
Scroll and mounting belong to the precious national culture and art that the Korean ancestors created and developed together with Korean painting.
A scroll is a form of Korean painting with pictures or words that are mounted for hanging down or rolling.
A scroll is decorated on its border with thin strips or cloth that goes with the picture, and a horizontal bar is fixed to the bottom of the scroll so that it unrolls when it hangs down.
Korean paper is pasted to the back of the scroll for hardening, and paraffin is spread all over the back and rubbed for preventing folding lines.
A scroll amplifies the national taste in adorning pictures.
It also helps long storage and easy handling of Korean painting works.
Mounting is ornamentation of appearance of pictures including their backs and borders.
Vividly taking the national form from early ages together with Korean painting, the intrinsic national painting, mounting has developed, divided into scroll, folding screen, picture album, album of calligraphic works etc., according to the mission and purpose of pictures, individually with their own features.
Mounting plays an important role in enhancing the beauty of paintings and it provides an important guarantee for keeping painting works to posterity.
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Jo Dec 30, 2025
Density and viscosity are important quantities which describe the physical properties of liquid, and density is the most important thermo-physical property of hybrid nanofluids.
Many methods were proposed for density measurement of density or viscosity alone. Resonant sensors can measure density and viscosity simultaneously, so it has many applications in the fields of physical or chemical sensing in liquid.
In the measurement of liquid density and viscosity, the change of resonance parameters due to the parasitic parallel capacitance of resonator affects measurement accuracy.
In order to improve accuracy, An Nam Chol, a section head at the Faculty of Electronics, proposed a method for compensating the parasitic parallel capacitance of resonator by adding an electrode. In addition, he modeled a resonant sensor with a compensation electrode and determined the structural parameters through simulations and experiments.
He conducted some experiments to examine the effect of this method. The experimental results show that this method is valuable for compensation of parasitic parallel capacitance of an immersed resonant sensor in liquid.
You can find the details in his paper “Accuracy improvement of resonant sensor by an additional electrode in the measurement of liquid density and viscosity” in “Sensor Review” (SCI).
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Jo Dec 29, 2025
IGBT is a high-voltage high-power integrated circuit device and has a wide range of high-power switching applications such as mobile driving, power supply, railway transportation, industry control, etc.
The NPT-IGBT is a composite device of MOSFET and BJT. Since NPT-IGBT usually operates at high voltage and strong current, hot-carrier-induced degradation will be generated inside the device. Hot carriers with high energy will damage the oxide region of the device and the interface between silicon and silicon-dioxide, and will increase the trap charge of the interface and the oxide region.
Many researchers have described the issues on hot carriers of IGBT device, However, there have been reported a little literature that dealt with the reliability of hot carriers of NPT-IGBT.
Kim Hak Bong, a section head at the Institute of Semiconductor, analyzed the degradation mechanisms due to the hot carrier effect in NPT-IGBT through the voltage stress measurement, TCAD simulation and charge pumping measurement.
The results of the voltage stress measurement, TCAD simulation and the charge pumping measurement were consistent with the theoretical analysis.
For more information, you can refer to his paper “Analysis on Effect of Hot-Carrier-Induced Degradation of NPT-IGBT” in “Solid-State Electronics” (SCI).
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Jo Dec 28, 2025
The Trucklift slope hoisting system is an innovative transport technology for open-pit mines, and it considerably accelerates and cheapens transport from mines.
When a truck drives onto or off the platform at the lower loading station in the Trucklift slope hoisting system with varying profile of track, the platform motion influences the operation of the Trucklift slope hoisting system, and the configuration of inclined ropes hitched to the platform is varied.
In order to estimate the movement of platform at the lower loading station when a truck drives off or onto the platform, the movement of the truck on the platform and the lower loading station and the effect of sagged inclined ropes hitched to the platform should be considered simultaneously. The platform motion is related to not only the profile of track and parameters of truck and platform, but also the parameters of sagged inclined ropes hitched to the platform.
Kim Kwang Hyok, a researcher at the Faculty of Mining Engineering, has investigated the platform motion with consideration of sagged inclined ropes when a truck drives off or onto a platform at the lower loading station in the Trucklift slope hoisting system with varying profile of track. He proposed a system of non-linear equations to furnish an explicit solution for extensible sagged inclined ropes with edges on the inclined track, simulated platform motion by using the ADAMS software, and modeled the sagged inclined ropes hitched to the platform as a flexible body with consideration of elasticity and bend.
The simulation result shows that the displacement of platform is not considerable in comparison with the diameter of a tire, and proper design of a lower loading station enables safe movement of trucks on the platform without arresters.
You can find the details in his paper “Platform Motion at Lower Loading Station in Trucklift Slope Hoisting System with Varying Profile of Track” in “Journal of Mining and Environment” (SCI).
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