• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1835-1837
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• 2004

The UHF electromagnetic waves excited by PD pulses propagate along the GIS busbar not only TEM mode, but also TE and TM mode. Generally the waves detected by the UHF sensors are those of high order modes and such waves can only propagate the higher than cut-off frequency. In this paper, computed cut-off frequency of 362[kV] GIS by each modes and simulated electromagnetic field of each propagation modes by FEM(Finite Element Method) program. Frequency band of each TEmn/TMmn modes were determinated by simulation results and were discussed optimal position of UHF sensor from this results.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.241-245
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• 2000

In this paper, VHF(30~230[MHz]) electromagnetic waves radiated from partial discharge(PD) at two-type electrodes in air are measured and the peculiar patterns of their spectra are reported. Also, the polarization and distance characteristics of electromagnetic wave rediated by PD, were investigated. In case of epoxy insulator in inserted, the noise level of radiated electromagnetic waves is 0.6~6.2[dB] higher than the case in air at below 90[MHz]. The frequency spectrum distribution of radiated electromagnetic waves appears different in the whole frequency range according to the arrangement of antenna.

• 한국전기전자재료학회논문지
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• 제19권2호
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• pp.162-168
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• 2006

Recently, diagnosis techniques have been investigated to detect a Partial Discharge associated with a dielectric material defect in a high voltage electrical apparatus, However, the properties of detection technique of Partial Discharge aren't completely understood because the physical process of Partial Discharge. Therefore, this paper analyzes the process on surface discharge of polymer insulator using wavelet transform. Wavelet transform provides a direct quantitative measure of spectral content in the time~frequency domain. As it is important to develop a non-contact method for detecting the kaolin contamination degree, this research analyzes the electromagnetic waves emitted from Partial Discharge using wavelet transform. This result experimentally shows the process of Partial Discharge as a two-dimensional distribution in the time-frequency domain. Feature extraction parameter namely, maximum and average of wavelet coefficients values, wavelet coefficients value at the point of $95\%$ in a histogram and number of maximum wavelet coefficient have used electromagnetic wave signals as input signals in the preprocessing process of neural networks in order to identify kaolin contamination rates. As result, root sum square error was produced by the test with a learning of neural networks obtained 0.00828.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.237.2-237.2
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• 2007

• 한국전자파학회논문지
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• 제13권1호
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• pp.87-93
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• 2002

기존의 공진산란이론에서는 하나의 모드에 대한 부분파 산란장이 주파수에 대하여 급격히 변하는 공진성분과 서서히 변하는 배경성분의 합으로 이루어졌다고 가정하고 적당한 배경성분을 제거하여 공진성분을 추출했다. 최근에 음향학 분야에서 산란 5-함수의 곱셈전개에 근거를 둔 새로운 공진 산란이론이 개발되어 왔다. 산란장이 공진성분과 배경성분 이외에 이들의 상호간섭성분으로 구성되어 있다고 제안한 이 이론은 공진성분의 크기뿐만 아니라 위상스펙트럼을 정확하게 얻게 해 주었다. 전자기파 분야에서는 유전체로 코팅된 도체 구 혹은 원통의 산란문제에 이 이론이 성공적으로 적용되었다. 본 논문에서는 유전체 실린더의 전자기파의 산란문제로 이 이론을 확장하고 수치계산으로 그 유효성을 검증했다.

• 조명전기설비학회논문지
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• 제17권4호
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• pp.50-56
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• 2003

본 논문에서는 유입변압기 진단을 목적으로 부분방전시 발생하는 여러 가지 물리적 화학적 현상중 초음파를 검출하기 위하여 광섬유 Mach-Zehnder 간섭계를 구성하였다. 구성된 광섬유 센서의 초음파 검출 평가 실험을 실시하고, 절연유 중에 배치한 침-평판전극에 교류 고전압을 인가하여 방전시 발생하는 초음파를 측정하고 퓨리에 변환 및 wavelet 변환을 이용한 데이터 분석 결과를 나타냈다.

• 조명전기설비학회논문지
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• 제22권5호
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• pp.47-52
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• 2008

본 논문에서는 모의 GIS 내부에 도전성 파티클, 미소돌기, 연면방전을 모의함으로 전하의 축적과 전계의 집중이 용이하도록 하여 부분방전을 모의하였다. 이때 부분방전 발생과 진전에 따른 방사전자파를 스펙트럼 분석기와 EMI EMC 측정용 안테나($30{\sim}2,000[MHz]$)를 사용하여 측정 분석하였다. 이러한 결과를 바탕으로 0.3[GHz]에서 1.7[GHz]대역에서 UHF법을 활용한 절연진단이 가능한 UHF 구형 센서를 설계하였다. 이러한 연구결과는 $SF_6$를 사용하는 실제 GIS 및 전력설비의 UHF 절연진단 시스템에 적용 가능한 UHF 진단센서로 활용할 수 있을 것이다.

• 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 2001년도 추계학술대회 논문집 전력기술부문
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• pp.403-405
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• 2001

This paper presents the detection method of partial discharge in metal clad switchgear(MCS) using electromagnetic technique. Two antennas are located in the inside and outside of the MCS, and electromagnetic waves detected by these antennas are analyzed and compared by FFT method in order to identify an insulation abnormality. As a result of the experiment by the proposed method, we show the detection possibility for partial discharge in the MCS. The proposed method is expected to apply to insulation condition observation and an accident prevention in the MCS effectively.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.856-862
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• 2013

A cavity-backed two-arm spiral antenna for partial discharge diagnosis is presented. The proposed antenna consists of a two-arm Archimedean spiral, a tapered microstrip balun as spiral antenna feed, and a ring-shaped absorber-loaded cavity. The Archimedean spiral antenna is designed for the operating frequency band of 0.3 GHz to 1.5 GHz and fed by the tapered microstrip balun. The cavity is utilized to transform the bidirectional beam into a unidirectional beam, thereby enhancing gain. The ring-shaped absorber is stacked in the cavity to reduce the reflected waves from the cavity wall. The proposed antenna is designed and simulated using CST Microwave Studio. A prototype of the proposed antenna is likewise fabricated and tested. The measured radiation patterns are directional to the positive z-axis, and the measured peak gain is 8.13 dBi at a frequency of 1.1 GHz.