Jo Jan 9, 2026
PTN (Packet Transport Network) based on MPLS-TP (Multi-Protocol Label Switching-Transport Profile) does not rely on subscriber service signals. It provides real-time transmission and robust OAM (Operation, Administration and Maintenance) functions thanks to VPN (Virtual Private Network) technique using LSP (Label Switch Path) and PW (Pseudo-Wire) for transparent transport, thus being widely used in transport systems for mobile communication.
The PTN for 3rd generation mobile communication is operated in the centralized way, and it is difficult to apply to the next generation mobile communication.
Kim Myong Jun, a researcher at the Faculty of Communication, has proposed a method of how to apply MPLS-TP based PTN device using dedicated network processor WINPATH to the next generation systems, and verified its application possibility.
The experimental results show that transport network for next generation can adopt MPLS-TP based PTN device by the proposed method.
...
Jo Jan 9, 2026
Radiation leaking into the surrounding environment has a detrimental effect on the human body, so it should be evaluated first to prevent it.
The most considerable radiation affecting the human body is gamma rays. This is because the penetrability of gamma rays is the strongest of all other kinds of radiation. Therefore, gamma dose measurement is of paramount importance for its dosimetry.
Radiation detectors for environmental radiation monitoring usually include scintillation detectors, ionization chambers, and automatic discharge counters. Among them, automatic discharge counter tubes are widely used for environmental radiation monitor fabrication because of their low cost and simple measurement circuitry. However, the automatic discharge counter tubes manufactured at home and abroad have the disadvantage of narrow energy band for dose estimation and low counting rate.
Pak Yong, a researcher at the Institute of Analysis, has designed a new environmental radiation monitor to measure radioactive contamination and environmental radiation.
By applying the time-count conversion method, he eliminated the effect of dead time in the GM counter tube and extended the counting rate measurement range from 2×103 to 105cells/s.
The proposed monitor enables measurement from 10nSv/h to 200mSv/h using two GM counters with improved properties.
...
Jo Jan 8, 2026
The earth’s crust is in ceaseless movement by the physical and chemical process of lava underneath itself and the gravitation force between the earth and other celestial bodies including the sun and the moon. Monitoring the tilt change of the earth’s crust is critical to detect the signs of crustal deformation.
A tiltmeter is an instrument for monitoring the ultra-fine tilt change of the crust (about 150nrad/day). Nowadays, geophysical scientists and researchers predict the precursory activity of natural disasters including earthquakes and volcanoes by analyzing the monitored data of tilt change. The earth tide tiltmeter is so accurate and sophisticated that it is usually expensive.
Ri Hyok Min, a researcher at the Institute of Nano Science and Technology, developed a low-cost tiltmeter based on a capacitive micro-displacement sensor and conducted a calibration and field test.
The micro-displacement sensor is a differential capacitive one, which consists of two fixed plates and a movable plate. The movable plate is the bob of the vertical pendulum which reflects the tilt of the earth’s crust. The sensor signal is pre-amplified by the Low-Z type amplifier and then processed by the lock-in amplifier.
He calibrated the tiltmeter by using the heavy block method. He verified the measured data of the developed tiltmeter by using MATLAB. The prototype of the developed tiltmeter had been installed in the dedicated laboratory to be operated for 4 months.
The results show that the developed tiltmeter is simple and cheap for monitoring the tilt of the earth’s crust and it is useful for predicting the precursor of earthquakes and volcanoes.
...
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.
...
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).
...
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).
...