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전력설비의 열화 진단을 위한 연면방전 모델에서의 코로나 방전 특성 분석
방만식,최재형,김우진,김영석,김상현,Pang, Man-Sik,Choi, Jae-Hyeong,Kim, Woo-Jin,Kim, Young-Seok,Kim, Sang-Hyun 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.4
Recently, ultrasound, infrared detector, V-I characteristic, gas analysis, UV (ultra-violet rays) camera etc. is used as inspections and diagnoses of the safety of power equipment. Especially, UV camera have attracted a great deal of interest from the view point of easy judgement. UV camera is used corona discharge. One of the most important and difficult problems to be solved filer design, materials and corona discharge. This paper is studied on the temperature characteristics, UV generation and shape analysis and corona pulse count according to the electrode distance and applied voltage. Also, Corona discharge characteristics in air are analyzed using prototype UV camera of Korea. UV generation due to surface discharge of AC is higher than that of DC.
기중 부싱모델의 오염물질에 따른 방전 특성과 자외선 이미지
방만식,최재형,김우진,김영석,김상현,Pang, Man-Sik,Choi, Jae-Hyeong,Kim, Woo-Jin,Kim, Young-Seok,Kim, Sang-Hyun 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.12
A bushing is very important because it must supply the high voltage to the power equipment. Generally, the surface of bushing is contaminated with rain, dust, salt and others. A bushing with contaminations at air are serious problem in insulation. Therefore, it is important to understand the inspection and diagnoses of the safety. The ultra-violet rays(UV) camera has attracted interest from the view point of easy judgement. In this paper, we will report on the corona discharge characteristics on bushing model with contaminations. Also, UV images of discharge in air are analyzed using prototype UV camera of Korea. These results are studied at both AC and DC voltage under a non-uniform field.
방만식(Man-Sik Pang),최재형(Jae-Hyeong Choi),김우진(Woo-Jin Kim),김영석(Young-Seok Kim),김상현(Sang-Hyun Kim) 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.5
Recently, UV(ultra-violet rays) camera has attracted a great deal of interest from the view point of easy judgement in inspections and diagnoses of the safety of power equipment. Especilly, UV camera is applied the inspection of UV with corona discharge. One of the most important and difficult problems is the basic research of filter design, materials and corona discharge. In this paper, we will report on the UV generation, corona pulse count and the polarity effect of positive and negative DC surface discharge in air. Also, corona discharge characteristics are analyzed using prototype UV camera of Korea. UV generation and corona pulse count due to surface discharge in positive needle is higher than that of negative needle.
방만식(Man-Sik Pang),최재형(Jae-Hyeong Choi),김우진(Woo-Jin Kim),김상현(Sang-Hyun Kim) 한국조명·전기설비학회 2011 한국조명·전기설비학회 학술대회논문집 Vol.2011 No.5월
Recently, UV camera have attracted a great deal of interest from the view point of easy judgement. UV camera is used corona discharge. One of the most important and difficult problems to be solved filer design, materials and corona discharge. This paper is studied on the UV generation and shape analysis and corona pulse count according to the electrode distance and applied voltage. Also, Corona discharge characteristics in air are analyzed using prototype UV camera of Korea. UV generation due to surface discharge of AC is higher than that of DC.
오염물질에 따른 변압기부싱 모델의 기중 코로나 방전 특성
방만식(Man-Sik Pang),김우진(Woo-Jin Kim),김영석(Young-Seok Kim),김상현(Sang-Hyun Kim) 한국조명·전기설비학회 2012 조명·전기설비학회논문지 Vol.26 No.5
The surface of bushing is contaminated with rain, dust, salt and others. A bushing with contaminations in air is serious problem in insulation. Therefore, it is important to understand the inspection and diagnoses of the safety. The ultra-violet rays(UV) camera has attracted interest from the view point of easy judgement. In this paper, we will report on the corona discharge characteristics of surface flashover model with contaminations in air. Also, UV images of discharge and corona pulse count in air are analyzed using prototype UV camera of Korea and a UV sensor with an optic lens. These results are studied at both AC and DC voltage under a non-uniform field.
고온초전도 직류 케이블용 절연재료인 PPLP의 직류 및 임펄스 절연 특성
김우진,방만식,김해종,조전욱,김상현,Kim, Woo-Jin,Pang, Man-Sik,Kim, Hae-Jong,Cho, Jeon-Wook,Kim, Sang-Hyun 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.7
To realize the high-Tc superconducting (HTS) DC cable system, it is important to study not only high current capacity and low loss of conductor but also optimum electrical insulation at cryogenic temperature. A model HTS DC cable system consists of a HTS conductor, semi-conductor, cooling system and insulating materials. Polypropylene laminated paper (PPLP) has been widely adopted as insulating material for HTS machines. However, the fundamental insulation characteristics of PPLP for the development of HTS DC cable have not been revealed satisfactorily until now. In this paper, we will discuss mainly on the breakdown characteristics of 3 sheets PPLP in liquid nitrogen ($LN_2$). The characteristics of the diameter, location of butt-gap, distance between butt-gap length, pressure effect, polarity effect under DC and impulse voltage were studied. Also, the DC polarity reversal breakdown voltage of mini-model cable was measured in $LN_2$ under 0.4 MPa.
전력설비의 열화진단을 위한 코로나 방전의 자외선 이미지와 전기적 특성
최재형(Choi, Jae-Hyeeong),방만식(Pang, Man-Sik),김우진(Kim, Woo-Jin),김영석(Kim, Young-Seok),김상현(Kim, Sang-Hyun) 한국화재소방학회 2011 한국화재소방학회 학술대회 논문집 Vol.2011 No.추계
최근, 전력설비의 열화진단 및 안전검사에 있어 편의성과 활용성의 측면에서 자외선 카메라가 많은 관심을 받고 있다. 자외선 카메라는 전력설비의 코로나 방전에 의한 자외선 검출을 응용한 기기로서 열화지점과 열화정도를 이미지 형태로 직관적으로 나타낼 수 있다. 따라서 전력설비의 정확한 열화진단을 위해서는 코로나 방전에 대한 전기적 특성과 자외선 특성에 대한 이해가 중요하다. 본 논문에서는 전력설비의 열화진단을 위한 코로나 방전을 모의하고, 그에 따른 자외선 이미지와 전기적 특성에 관해 연구하였다.
방만식,장두봉,김영일 慶尙大學校生産技術硏究所 1995 生産技術硏究所論文集 Vol.11 No.-
Since the Korean speech can be phonetically classified according to the characteristic and structure of its pronunciation. Korean syllables are divided into the phonemes such as consonants, vowels, and end consonants. So, both the processing time and the signal data can be reduced by analyzing the phonemes instead of the isolated speeches. In this paper, we use the linear prediction coefficient and cepstrum coefficient at the parameter, and use ltakura-Saito distance measure as the similarity measure. First, in order to obtain the similarity in phonemes of an isolated speech, we study the acoustic similarity between the frame and its adjacent frame serially, and show, that the similarity is found in the interval of the similar phoneme and the dissimilarity is found in the interval of transition of the phoneme. In addition, after taking the single frame inside an isolated speech, we compare the parameter of the frame with the different isolated speech serially for the search of the same phoneme in the isolated speech. It turns out that the same phonemes have similar acoustic characteristics. Finally we obtain the similarity measure of each phoneme by comparing the same phonemes of two different isolated speeches. Furthermore, we also compare with phoneme with different phonemes. As a result, we obtain that the similarity is found between the same phonemes even though the phonemes are in the different isolated speeches.
영상정보를 이용한 자율 이동 로봇의 장애물 회피 및 경로계획에 대한 알고리즘
구본민,방만식,김자룡 진주여자전문대학 2001 論文集 Vol.24 No.-
In this paper, we has been studied self-controlled mobile robot system with CCD camera. This system consists of TMS320F240 digital signal processor, step motor. RF module and CCD camera. we used wireless RF module for movable command transmitting between robot and host PC. This robot go straight until 93 percent filled screen from input image. And the robot recognizes obstacle about 95 percent filled something, so it could avoid the obstacle and conclude new path plan.
이상기,방만식 진주여자전문대학 1999 論文集 Vol.22 No.-
ZnO varistors containing 5.0 at% Co_(3)O_(4). 0.7at% Pr_(6)O_(11) and CaCO_(3) ranging from 0 to 1.0 at%, were sintered at 1200℃ 1250℃ and 1300℃. The densities are 93-98% relative densities of pure ZnO. The liquid phase mainly consisting of praseodymium oxide was observed at the grain boundaries for the specimens sintered at 1250℃ and 1300℃, but second phase isn't found at grain boundaries for those sintered at 1200℃. The reported data for the liquid phase formation temperature of ZnO-Co_(3)O_(4)-Pr_(6)O_(11) ternary composition is higher than 1280℃. Therefore it is concluded that the addition of Ca decreases the liquid phase formation temperature and pronounced increase of grain size for the specimens sintered at 1250℃ and 1300℃ is resulted from liquid phase sintering. The increase of grain size with sintering temperature result in low breakdown field and high leakage current for the specimens sintered at higher temperature. For the samples sitered at 1200℃ and 1250℃ the nonlinear coefficient, the breakdown voltage per grain boundary and the leakage current changed significantly above 0.8at% Ca. However, those measured for the specimens sintered at 13009: did not show the same trend except the leakage current. The different effect of C a content for the specimens sintered at 1200℃ and 1250℃ and for those fired at 1300℃ is attributable to the liquid phase formed along the grain boundaries. The liquid phase completely surrounds the grains for the specimens sintered at 1300℃, which possibly makes any change in grain boundary property due to excess amount of Ca insignificant. The carrier density and potential barrier heights were obtained using capacitance-voltage plot. For the specimens sintered at 1200℃ and 1250℃ the carrier density increased with Ca content up to 0.6at%. Again the decrease of the carrier density for the samples with excessive Ca content, 0.8at% and 1.0at%, was observed. The barrier heights estimated for the specimens did not show specific relation with Ca content nor sintering temperature.