• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.207-210
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• 2002

In this paper, We have measured the luminous flux variation of electrodeless fluorescent lamp system reducing a power source to 70% and applying a short interruption caused by the power failure. So we can understood that the protective device for apparatus of power sources is important thing to control electrodeless fluorescent lamp system.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.244-247
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• 2006

본 논문에서는 누전차단기에 대한 고조파 영향을 규명하기 위해 고조파 합성장치를 이용하여 누전차단기 동작특성을 시험하였다. 시험결과 3차 고조파가 기본파에 합성되었을 때 기본파보다 작은 값의 누설전류에서 누전차단기가 동작되어 오동작 될 수 있는 가능성이 있었고 기본파에 더해진 고조파 차수가 증가할 수 록 누전차단기 동작전류는 증가하였다. 따라서 사무용 빌딩 등과 같이 3차 고조파가 존재하는 장소에서는 누전차단기가 오동작 될 수 있으므로 사용에 주의가 필요한 것으로 나타났다.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.463-468
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• 1987

In this paper, a high impedance fault detection on 22.9kV multigrounded distribution system that has been very difficult by any existing conventional protective relaying systems is studied. Because the fault current is very low, it cannot be distinguished from neutral current caused by load unvalanced on multigrounded distribution system. We developed the new and best algorithms of high impedance ground fault detection. This algorithms are 'the even order power method, even order ratio method', 'and even order ratio varience method'. Using this algorithms, a detection device for high impedance faults is constructed and tested in the laboratory. And continually, it is installed and has been tested in KEPCO substations.

• KIEE International Transactions on Power Engineering
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• v.4A no.3
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• pp.122-128
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• 2004

With the advent of distributed generation, power systems are fundamentally impacted in regards to stability and power quality. Distributed generation has a positive impact on system restoration following a fault, higher reliability, and mitigation of effect due to voltage sag. However, distributed generation also has a negative impact on decrease of reliability such as changes of protective device setting and mal-operation. Because bulk power systems consist of various sources and loads, it becomes complicated to analyze a power system with distributed generation. The types of distributed generation are usually classified by both rotating machinery and the inverter-based system. In this paper, distributed generation is designed by rotating machinery, and the distributed system having a model of the distributed generation is simulated using EMTP. In addition, this paper presents the simulation results according to the types of distributed generation.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.278-281
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• 2001

Identifying the fault location has to deal with multiple possible candidates. It presents a new technique to diagnosis a fault region. The proposed diagnosis scheme identifies accurately the location based on the protective device operations and load current change at the substation. An Expert system is presented using these facts.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.198-205
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• 2005

Reduction of labor hour for cleaning up of the used abrasives after blasting. is attempted by improving the efficiency of abrasive recovery process in the protective coating of ship's block, For this purpose, the theoretical background for pneumatic transport technology in the abrasive recovery system as well as experimental evaluation on the effect of design parameters such as flow pattern, saltation velocity and pressure drop on the efficiency of the abrasive recovery system are employed . By optimizing the operating parameters such as the length and diameter of the suction hose, specification of recovery device and recovery mouth, a new method which can dramatically increase the efficiency of abrasive recovery system, is proposed.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.546-547
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• 2013

This paper proposes an arc fault circuit interrupter (AFCI) using the distorted voltage wave in electric arc faults. It perceives a voltage instantaneously at the time of voltage drop. and occurrence. It is an AFCI of the new concept which operates with high reliability. The primary reason of electric fire is arc and spark. It prevents an electric fire or an electric leakage accident with quick responsiveness. Earth Leakage Circuit Breaker(ELB), Molded_case Circuit Breaker (MCCB) or Residual Current Protective Device(RCD) can not cut off electric arc or spark to be a major factor of electrical fire. This theory will be able to intercept an arc or a spark. which occurrence with periodic. Consequently It raises a reliability and validates a practicality of RCD.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2525-2527
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• 2000

The analysis of distribution line faults is essential to the proper protection of power system. A high impedance fault(HIF) dose not make enough current to cause conventional protective device operating, so it is well known that undesirable operating conditions and certain types of faults on electric distribution feeders cannot be detected by using conventional protection system. In this paper, we prove that the nature of the high impedance faults is indeed a deterministic chaos, not a random motion. Algorithms for estimating Lyapunov spectrum and the largest Lyapunov exponent are applied to various fault currents detections in order to evaluate the orbital instability peculiar to deterministic chaos dynamically, and fractal dimensions of fault currents which represent geometrical self-similarity are calculated. Wavelet transform analysis is applied the time-scale information to fault signal. Time-scale representation of high impedance faults can detect easily and localize correctly the fault waveform.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.176-177
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• 2006

The main aim of the paper is the study of the surge voltages in electric railway signal security system. Hence these studies will provide means of introducing a suitable protective device insulating transformer. This influences the surge voltage interrupting capacity using surge arresters and bypass capacitors. This circuit can be used for investigating surge phenomenon in electric railway signal security system. In this paper a insulating transformer has been introduced for the reduction of surge voltages in the above circuit model and performance evaluation.

• ETRI Journal
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• v.35 no.4
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• pp.603-609
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• 2013

In this paper, we present a 600-V reverse conducting insulated gate bipolar transistor (RC-IGBT) for soft and hard switching applications, such as general purpose inverters. The newly developed RC-IGBT uses the deep reactive-ion etching trench technology without the thin wafer process technology. Therefore, a freewheeling diode (FWD) is monolithically integrated in an IGBT chip. The proposed RC-IGBT operates as an IGBT in forward conducting mode and as an FWD in reverse conducting mode. Also, to avoid the destructive failure of the gate oxide under the surge current and abnormal conditions, a protective Zener diode is successfully integrated in the gate electrode without compromising the operation performance of the IGBT.