• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.868-869
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• 2008

An automatic excitation characteristics measurement system for the protective relaying current transformer(CT) with accuracy of about 1 % has been developed. The system can be used up to 2 kV and 10 A at power frequency. The developed system can calculate the voltage and current at knee points of $30^{\circ}$ and $45^{\circ}$ tangents in accordance with IEEE standard by the interpolation in log scale. The excitation curve of the CT is plotted in auto-scale simultaneously with measuring rms voltage and current at the secondary of the CT.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.215-216
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• 2015

The application of fault current limiter(FCL) reduces power system fault current for circuit breaker to operate properly due to reduced fault current. Also FCL reduces through fault current to the power system equipments. But FCL has changed power system parameters for short time, before application the magnitude of register, triggering current and protective relay coordination have to be studied. In this paper we will examine protective relay coordination with FCL. And propose better solution to assist improving of power system operation through the application of FCL.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.2
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• pp.99-106
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• 2003

In this paper, an intelligent fault location and diagnosis system is proposed. The proposed system identifies the fault location in two-step procedure. The first step identifies candidates of fault location using an fault distance calculation using an iterative method. The second step is diagnosis the actual fault location in the candidates by comparing the current waveform patterns with the expected operation of the protective devices and considering the interrupted load after the operation protective device. The simulations results in the case study demonstrates a good performance of the proposed fault location and diagnosis system.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.905-907
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• 1998

The setting of protective relays, which is critical to the system security, requires a huge volume of data and a lot of repetitive calculations. Since an effective design of a database is essential. The relay setting database must accommodate a variety of protective devices. Also its information can be viewed and updated with easy by humans and by computer programs. This paper describes several existing database designs for power system protection, their advantages and disadvantages. Also this paper develops an effective database for power system protection with their advantages.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1107-1114
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• 2012

In this paper, we propose protective coordination and automatic setting method using agents for distribution system with loop. The proposed protection scheme adopts an agent technology assuming communication among protection agents and auto-switch agents. Having exchanged fault-related information with each other, protection agents and auto-switch agents perform the primary and backup protection and fault section isolation, respectively. this proposed scheme using agents for distribution system with loop is implemented by matlab. Because of the various configuration of distribution system, It's difficult to find cooperative agents for each agent. This paper develops a program to automatically set the cooperative route for the agents.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.77-86
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• 2005

The DC protection and control device for the feeding system of a Light Rail Transit(LRT) system is developed. For the development, the short circuit characteristics in the system are analyzed. As a result a protection algorithm for the DC fault selective relay (50F) is newly proposed, and principles of the DC fault selective relay, Line Test Device (LTD), DC Over Current Relay (DC OCR) are introduced From the development, the specifications and codes used to be unclear have become clarified and summarized. Moreover, the methods to examine the protective characteristics and Electromagnetic Compatibility (EMC) are established Finally, the performance and the effectiveness of the developed protective relay have been verified with the test based on IEC. For the reliability of the system, the relay has been installed and is being operated at the test track of the LRT system at Gyeong-San.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.4
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• pp.210-215
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• 2013

This paper analyze the bus voltage sags in the power distribution system with a small scale cogeneration system when the superconducting fault current limiter was introduced. Among the solutions to decrease the short-circuit current considering the locations of the small scale cogeneration system, the superconducting fault current limiter (SFCL) has been announced as one of the promising methods to reduce the fault current because the installation of the small scale cogeneration system which increases the short-circuit current. According to the application locations of the small scale cogeneration system in a power distribution system, it has caused the variations of voltage sag and duration which depends on the change of the short-circuit current, which can make the operation of the protective device deviate from its original set value when the fault occurs. To investigate the voltage sag when a SFCL was applied into a power distribution system where the small scale cogeneration system was introduced into various locations, the SFCL, small scale cogeneration system, and power system are modeled using PSCAD/EMTDC. In this paper, the effects on voltage sags are assessed when the SFCL is installed in power distribution system with various locations of the small scale cogeneration system.

• The Korea Journal of Herbology
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• v.20 no.2
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• pp.115-125
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• 2005

Objectives : Polygalae Radix (PR) from Polygalae tenuifolia (Polygalaceae) has been clinically used as a sedative, anti-inflammatory, and anti-bacterial agent. To extend pharmacological effects of PR in the central nervous system (CNS) on the basis of its CNS protective effect, the present study was conducted to identify the effect of PR, whether it shows the neuroprotective action against excitatory neurotoxicity. Methods : To identify the protective effect of PR to excitatory neuro-toxic agent, the present study was focused on the PR effect on cell death, that was caused by applying NMDA to nerve cell, elevation of $(Ca^{2+})_i$, releasement of glutamate, and ROS generation. Result : 1. PR methanol extract, at the concentration range of 0.05 to 5 g/ml, significantly inhibited NMDA (1 mM)-induced neuronal cell death as well as MK-801 (non competitive NMDA antagonist). 2. PR methanol extract $(0.5\;{\mu}g/ml)$ inhibited NMDA (1 mM)-induced elevation of cytosolic calcium concentration $[Ca^{2+}]_i$. NMDA application in the presence of MK-801 $(10\;{\mu}M)$ failed to produce the increase of $[Ca^{2+}]_i$ through all the measurement time. 3. PR methanol extract $(0.5\;{\mu}g/ml)$ inhibited the NMDA-induced elevation of glutamate release. Also, MK-801 showed similar protective effects. 4. PR methanol extract $(0.5\;{\mu}g/ml)$ inhibited the NMDA-induced elevation of ROS generation. Also, MK-801 showed similar protective effects. Conclusion : The present study provides the availability of PR to exert its protective effect on the neuronal cell death in various neurodegenerative pathophysiological conditions.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.3
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• pp.294-301
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• 2020

Man-In-Simulant Test(MIST) provides a test method to evaluate chemical protective equipments such as protective garments, gloves, footwear and gas mask. The MIST chamber is built to control concentration of chemical vapor that has a activity space for two persons. Non-toxic methyl-salicylate(MeS) is used to simulate chemical agent vapor. We carried out to measure inward leakage MeS vapors by using passive adsorbent dosimeter(PAD) which are placed on the skin at specific locations of the body while man is activity according to the standard procedure in MIST chamber. But more time is required for PADs and there is concern of contamination in PADs by recovering after experiment. Therefore detector for measuring in real time is necessary. In order to analyze in real time the contamination of the personal protective equipment inside the chemical environment, we have developed a wireless real-time gas detector. The detector consists of 8 gas-sensors and 1 control-board. The control-board includes a CPU for processing a signal, a power supply unit for biasing the sensor and Bluetooth-chipset for transmission of signals to external PC. All signals from gas-sensors are converted into digital signals simultaneously in the control-board. These digital signals are stored in external PC via Bluetooth wireless communication. The experiment is performed by using protective equipment worn on manikin. The detector is mounted inside protective equipment which is capable of providing a real-time monitoring inward leakage MeS vapor. Developed detector is demonstrated the feasibility as real-time detector for MIST.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.56-62
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• 2010

This paper describes the analysis of loop impedance characteristics by impedance alteration of protective conductors and operating characteristics of electric leakage circuit breaker by each earth systems(TT system, TN-S system and TN-C system) in IEC 60364. As a result, loop Impedance was affected by resistance & inductance. The current& voltage characteristics about earth system were identified that the TN-S system was high fault current & low touch voltage. TN-C system was almost same the TN-S system but TT system was low fault current & high touch voltage.