• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1647-1649
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• 1998

This paper describes the power frequency voltage and its countermeasure when a 765 kV transmission line is directly connected to a 345 kV line and operated at 345 kV voltage. The summary of this result is as follows : The western route of 765 kV transmission line doesn't need any countermeasure to reduce the power frequency voltage at the receiving end. The eastern route of 765 kV transmission needs 100 Mvar(3 phase) capacity of shunt reactor at the receiving end to reduce the power frequency voltage. The use of shunt reactors in the 765 kV transmission lines has unexpected problems, one of which is induction of high voltages on a de-energized circuit of two parallel lines. This paper examined the problem of resonance on two parallel transmission circuits in one routes.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1003-1005
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• 1997

To evaluate the quality of a system or its ability to perform a required function, it is necessary to quantify the reliability of that system. The reliability techniques are based on the concept of expected failure rate and average-outage-duration method. For each load point, the expected failure rate, average outage duration and average annual outage time are evaluated. This paper deals with the reliability evaluation for distribution system including the protection relay system. In evaluating the reliability, it suggests a method for the analysis of protective system reliability, that provides a probabilistic measure of the success of the protective apparatus to perform its intended function. The analysis shows the dependency of success on the reliability of many components, and the way this reliability may be enhanced by redundancy.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1133-1136
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• 1997

This study established AC-DC system model including DC Link, and then BC Link equation was derived from the model. The equation was included into the calculational algorithm of AC system and solved using fast decoupled method. To minimize the line loss of AC-DC system, optimum theory was applied to the equations.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1056-1059
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• 1997

Thyristor-Controlled Series Compensation (TCSC) is expected to be applied in transmission systems to achieve a number of benefits. TCSC can provide such assistance for stability, as well as helping to direct flows onto desired transmission paths. This paper describess a TCSC model which can be used for typical transient and oscillatory stability studies. Also included is a discussion on relevant information to extend the modeling detail of the TCSC for use stability analysis.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1067-1070
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• 1997

This paper presents an algorithm that evaluates load supplying capability(LSC) considering voltage constraint in composite power systems. To evaluate the LSC considering the voltage constraint, we apply tangent vector approach using an enhanced power flow method based on continuation algorithm. The validity and effectiveness of the proposed method is confirmed through the simulation of a model system.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.667-671
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• 1997

본 논문에서는 적응제어계통의 강인성을 향상시키기 위한 새로운 알고리즘을 제시한다. 이 적응 알고리즘은 외란의 영향을 상쇄시키고 Lyapunov 도함수 $V{\le}0$가 되도록 한다. 그 결과로서 외란이 존재하는 경우만 아니라 이상적인 경우에도 출력오차가 0에 수렴한다. 또한 컴퓨터 시뮬레이션과 DC 서보 전동기의 위치제어 실험을 통하여 $e_1$ 변형법과 실험결과를 비교함으로써 제안한 알고리즘의 타당성을 보여준다.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.316-320
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• 2008

This paper described the design and fabrication of a series arc detection module to monitor electrical insulation in low-voltage system. The module consists of a passive high-pass filter with a low cut-off frequency of 3 kHz to attenuate power frequency voltage by 80 dB and an active band-pass filter with a frequency of 4 kHz to detect series arc signals only. For the application experiment, we simulated series arcing phenomena on various loads such as incandescent lamp controlled by dimmer and inverter fed induction motors by an arc generator specified in UL1699. From the experimental results, we could detect series arc signals without an influence of noises.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.30-35
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• 2010

Recently, the large capacity draft fans in power plants had been changed to variable speed type to educe the power consumption. But the fan experienced the unexpected vibration at specific speed regions. In this study, the high vibration frequency of the fan was confirmed and the natural frequency of the rotor were measured and analyzed by FEM programs. It was analyzed that the vibration was caused by the resonance at the frequency, 30.7Hz. So, the rotor vibration characteristic was changed by adjusting the distance between the shaft bearings. It was conformed the high vibration was disappeared over the all operation speeds.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.308-310
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• 2008

향후 가까운 미래에 정부에서 주도하고 있는 10만호 보급사업 등을 포함한 대규모 태양광발전산업의 보급에 따라 특정지역에서는 계통연계형 태양광 전력변환기(PV PCS)의 고밀도 연계가 예상된다. 이 때 지금까지는 이론적으로만 가능할 것으로 여겨졌던 현상 인 단독운전 현상이 발생할 수 있는 확률이 높아지게 된다. 본 논문에서는 전력변동기법 중 하나인 무효전력변동기법에 대하여 단독운전검출 성능을 향상시키기 위한 한 방법으로 Digital Phase-Locked-Loop(DPLL)의 주파수계산을 이용하여 그 효용성을 PSIM 시뮬레이션을 통하여 검증하였다.

• Korean journal of applied entomology
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• v.33 no.3
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• pp.184-193
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• 1994

Ogma koesanense sp.n. has two head annuli. The first head annule is much larger than the second; blunt scales mare or less in 17-19 longitudinal l~nes and acute tail. Criconemello onnuiata. Criconema cardamoml, Ogma decalineaturn, 0. dtyum are newly recorded from Korea. Morphological characteristics of previously reported speaes, Ciiconema demani is discussed.