• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(2)
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• pp.902-903
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• 2005

• 호남수학학술지
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• 제35권4호
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• pp.683-699
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• 2013

In this paper, an improved ($\frac{G^{\prime}}{G}$)-expansion method is proposed for obtaining travelling wave solutions of nonlinear evolution equations. The proposed technique called ($\frac{F}{G}$)-expansion method is more powerful than the method ($\frac{G^{\prime}}{G}$)-expansion method. The efficiency of the method is demonstrated on a variety of nonlinear partial differential equations such as KdV equation, mKd equation and Boussinesq equations. As a result, more travelling wave solutions are obtained including not only all the known solutions but also the computation burden is greatly decreased compared with the existing method. The travelling wave solutions are expressed by the hyperbolic functions and the trigonometric functions. The result reveals that the proposed method is simple and effective, and can be used for many other nonlinear evolutions equations arising in mathematical physics.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.730-734
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• 2003

A beamforming method is a kind of spatial filter that focus the amy's signal capturing abilities in a desired direction. In this paper, we detect the location of a source under reflective condition using the multi-dimensional MUSIC algorithm then, we can iud the image source locations from the experimental geometry, and we reconstruct the partial fields for direct wave and reflected wave by using Adaptive nulling algorithm. Numerical simulations are performed to verify its performance under various conditions.

• 한국해안해양공학회지
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• 제13권2호
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• pp.158-168
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• 2001

불규칙파의 방향분산과 부분쇄파의 정도 높게 고려하기 위해 광각 포물형 근사식을 이용하는 수치모형이 수립되었다. 이 수치모형은 불규칙파를 여러 개의 단일주기의 규칙파로 분해한 다음, 각 성분파를 동시계산하여 중첩함으로써 합성파고를 구한다. 불규칙파의 부분쇄파를 고려하기 위해 합성파고를 이용하여 쇄파에 의한 에너지 감쇠량을 산정한다. 기존의 불규칙파 수리실험 결과와 비교하여 수립된 수치모형의 정확성을 검사한 바, 비쇄파의 경우 규칙파와 불규칙파 모두에 대해 상당한 정확도가 있음이 확인되었으나, 쇄파 발생 시에는 수치모형의 정도가 크게 저하됨을 발견하였으며, 그 이유에 대한 분석을 제시하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.145-149
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• 2001

The most of faults in gas insulation of power facilities are caused by partial discharge. Therefore we simulated partial discharge and measured the radiated electromagnetic wave emitted from partial discharge in SF$_{6}$ gas by biconical antenna. This paper describes time delay and electric fields pulse characteristics of radiated electromagnetic waves with distance(1[m], 3[m], 5[m]) between antenna and discharge source.e.

• 한국전기전자재료학회논문지
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• 제26권4호
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• pp.309-314
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• 2013

This paper dealt with the radiated electromagnetic wave detection of partial discharge (PD) in oil for insulation diagnostics of oil-immersed transformers. Three types of electrode system were fabricated to simulate the insulation defects that could occur in oil-immersed transformers. Frequency components of radiated electromagnetic wave in oil was measured by broadband bi-conical antennas of 300 MHz~2 GHz and a spectrum analyzer of 9 kHz~3 GHz. Frequency component of electromagnetic waves from PD in oil were highly distributed at 500 MHz. From the result, a narrow-band monopole antenna with the center frequency of 500 MHz was fabricated. We could detect PD signal in insulation oil without an influence of external noise by a measurement system which consists of the prototype monopole antenna, a LNA (Low Noise Amplifier), an oscilloscope and a spectrum analyzer.

• Transactions on Electrical and Electronic Materials
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• 제7권5호
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• pp.252-256
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• 2006

When a partial discharge takes place at the stator of a generator, the electrical pulse will propagate along the stator bars and the capacitor chains formed by the end part of the stator winds. On the first path, the pulse propagates as a travel wave at slow speed. On the second path, the pulse propagates at quick speed. Based on the data of the experiments on a real 50 MW steam generator, the author has found the pulses can propagate by magnetic field of the stator winding. It was studied that how to locating the partial discharge by signals coming from the different paths, including the features of signals on the two paths at time domain and frequency domain, the measurement frequency rang of the signals, the blind area, the advantage and disadvantage of this method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.97-98
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• 2008

In 6.6kV Rotary Machine Stator Windings, Corona Discharge, Discharge at Conductor Surface, Slot Discharge and Endwinding Discharge is happended by electronic degradation. Also, if Partial Discharge cause in inner-part of Rotary Machine Stator Windings, it will be happended voltage and current pulse. In case of discharge spark, RF electromagnetic wave, which transmits at discharge position, can happen. To detect this kind of RF electromagnetic wave efficiently, we have designed Planar Antenna Sensor with the CST MWS simulation program. Also we have confined the application possibility, which can analyzes the partial discharge in Rotary Machine Stator Windings. In the Future, sample of planar antenna sensor will be able to compare with the data of simulation by CST MWS program.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1748-1750
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• 2002

Partial discharge is attendant physical phenomenon on electromagnetic, sounds, lightning and mechanical vibration. In this paper, we simulated GIS and measured the radiated electromagnetic wave emitted from partial discharge in $SF_6$ gas using antenna(30[MHz] ${\sim}$ 2[GHz]) and spectrum analyzer. This paper describes characteristics of radiated electromagnetic waves with distance 1 [m] between antenna and discharge source.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.222-223
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• 2007

In 6.6kV Rotary Machine Stator Windings, Corona Discharge, Discharge at Conductor Surface, Slot Discharge and Endwinding Discharge is happended by electronic degradation. Also, if Partial Discharge cause in inner-part of Rotary Machine Stator Windings, it will be happended voltage and current pulse. In case of discharge spark, RF electromagnetic wave, which tranmits at discharge position, can happen. To detect this kind of RF electromagnetic wave efficiently, we have designed Planar Antenna Sensor with the CST MWS simulation program. Also we have confined the application possibility, which can analize the partial discharge in Rotary Machine Stator Windings. In the Future, sample of planar antenna sensor will be able to compare with the data of simulation by CST MWS program.