• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.957-960
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• 2008

The influences of silicon and MgO seed particle on the reconstruction characteristics of MgO protective layer were investigated to clarify the mechanism of reconstruction and exaggerated grain growth (EGG) in AC-PDP. The reconstruction and EGG are closely correlated with the driving force for nucleation and growth, interface energy and initial size distribution of MgO protective layer in plasma space during discharge in AC-PDP.

• Proceedings of the KIEE Conference
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• 2004.11d
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• pp.40-42
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• 2004

Electronic equipments made from electrical circuits with small-sized semiconductor are very weak against lightning surge. So, electronic equipments is protected by SPD(surge protective devices) such as Zno varistor. The SPD protect electronic circuit in electronic equipments and AC power lines from the lightning surge. Therefore to achieve effective method of surge protection, there are needs for correlation between lightning surge protective effect and installation method of surge protective device. Therefore this paper describes as a result of experiments for correlation between lightning surge protective effect and installation method of surge protective device.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.75-81
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• 2013

In this paper, protection coordination between residual current devices and surge protective devices in low-voltage consumer's distribution systems are presented. In the case that a surge protrctive device(SPD) is located on the load side of an residual current device(RCD), when the surge is injected from the source side of the RCD, most of injected surge currents are split into the RCD and the protection coordination between the SPD and RCD is improper, three of 6 specimens experience unintended operation due to test impulse currents. Also when the surges is injected from the load side, a lot of the surge currents is split into the SPD, but a half of test specimens causes nuisance trip. Coordination between SPD and RCD is not valid. When installing SPD, it is important to select SPD after due consideration of the protection voltage level of metal oxide varistor embedded in RCD. It is expected that the results obtained from this work could be useful to improve the protection effects of SPD in low-voltage distribution systems.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.1
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• pp.63-69
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• 2015

Recently, research and interests in pilotless and radio-controlled quadcopters have increased due to military, hobby, and air-photo applications. However, quadcopters are fragile and can very easily to break when they crash. Therefore, it is necessary to create a protective device such that these devices can protect the main board, motor, and propellers from outside impacts. In this paper, a protective device for a quadcopter is designed in the form of a circle to disperse shock. Also, a dropping and impact simulation was performed to verify that the quadcopter can be efficiently protected when using the proposed device, created with the commercial finite element software Solidworks.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.188-190
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• 2000

Protective Relays are vital components of power systems. The role of the protective relaying device is more important than ever. Therefore, We have investigated the operating trends of protective relay from 1991 to 1999. we anticipate that reliability in the power systems increases by improving design, manufacture, construction technology and maintenance method of the protective relay.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1873-1875
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• 1996

This paper deals with the lightning surge protective devices with combination of varistor and LC filter. UP to now, the varistor alone were used as overvoltage protection devices fer the AC power mains. In this work, in order to improve the cutoff performance of surge protective device, the hybrid circuit surge protective device for an AC single phase mains was designed and investigated. The first stage of hybrid circuit is to remove most of any large surge energy and protect the second stage components. The purpose of the second is to protect the load and increase the cutoff capacity of surge protective devices. Also LC filter attenuates the remnant that travels downstream from the first stage component and the high frequency noises. As a consequence, it was found that the proposed hybrid surge protective device for AC power mains has a variety of advantages such as low and tight clamping voltage, high frequency noise reduction and large cutoff capacity.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.102-108
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• 2015

This paper proposes a new fault isolation methodology for a smart protective device which plays an agent role on the smart grid distribution system with the distributed generation. It, by itself, determines accurately whether its protection zone is fault or not, identifies the fault zone and separates the fault zone through the exchange of fault information such as the current information and the voltage information with other protective devices using bi-directional communication capabilities on the smart grid distribution system. The heuristic rules are obtained from the structure and electrical characteristics determined according to the location of the fault and DG (Distributed Generation) when faults such as single-phase ground fault, phase-to-phase short fault and three-phase short fault occur on the smart grid distribution system with DG.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.11
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• pp.581-588
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• 2004

Power qualify monitoring system is devoted to more concern than before, because the innovation of industrial technology needs more accurate instruments and more advanced power quality. This paper was studied on using data of the protective relay by Power Quality Monitor. This paper was proposed the wave storage condition and monitoring clauses of the protective relay as a power quality monitoring device. The protective relay will have problem to save data for PQM analysis because the protective relay memory is limited. Therefore this paper was proposed new a data compression of data got from the protective relay. This method is wave compression comparison algorithm using the DFT. The compression rate is higher than any other established method. This method can be real time storage. This algorithm is verified using the comparison among other compression rate and proved by Real Time Digital Simulator (RTDS).

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.129-131
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• 2001

In order to improve the reliability of power service and the effective management of distribution power system. DAS (Distribution Automation system) is widely used in KEPCO(Korea Electric Power Corporation) branch offices. Based on the present protective device coordination program which used in KEPCO. this study presents the new concept about both protective device coordination program maximizing the characteristics of DAS and development plan of protective device auto-coordination program with the merits of DAS.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.39-45
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• 2015

This paper deals with development of integrity evaluation instrument for the power line surge protective device. A reliable power supply is an essential element in the developed information and communication society by highly advances in IT technology. However, the lightning incidence also increased with the recent extreme weather events. In Korea, in order to protect the electrical system from lightning surge, SPD(Surge Protective Device) has been used for these past 30 years. However, the method of diagnosing the safety of the SPD in the industry is insufficient. In this paper, SPD integrity evaluation system was composed of a variable DC power source unit, voltage-current sensor and the embedded controller. In order to measure V-I characteristics of MOV, 3 type samples were degraded by impulse current generator. After impulse tests, the varistor voltage of all samples and nonlinearity coefficient were decreased. It confirmed the utility of the developed equipment by this experimental test and the reliability of SPD is expected for surge accident prevention when applied to industrial plant.