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비선형 부하를 고려한 감쇠 진동형 임펄스 전류발생기의 설계 기법
張錫勳(Sug-Hun Chang),李在福(Jae-Bok Lee),S. V. Shenderey,明聖鎬(Sung-Ho Myung),趙延奎(Yuen-Gue Cho) 대한전기학회 2008 전기학회논문지 Vol.57 No.12
This paper presents a design parameter calculation methodology and its realization to construction for the damped oscillatory impulse current generator(ICG) modelled as damping factor α. Matlab internal functions, "fzero" and "polyfit" are applied to find α which are solutions of second order nonlinear equation related with three wave parameters T₁, T₂ and Ios. The calculation results for standard impulse current waveforms such as 4/10 ㎲, 8/20 ㎲ and 30/80 ㎲ show very good accuracy and this results make it possible to extend to generalization in the design of damped oscillatory ICG with any capacitor. 8/20 ㎲ ICG based on the calculated design circuit parameters is fabricated in consideration of the nonlinear load(MOV) variation. Comparisons of the tested waveforms with the designed estimation show error within 10% for the waveform tolerance recommended in IEC 60060-1 and IEEE std. C62.45.
초기 동맥혈 Carboxyhemoglobin 농도가 높았던 화상 환자들의 예후지표에 관한 연구
최창순 ( Choe Chang Sun ),김철홍 ( Kim Cheol Hong ),김근숙 ( Kim Geun Sug ),이태유 ( Lee Tae Yu ),정연손 ( Jeong Yeon Son ),엄광석 ( Eom Gwang Seog ),박용범 ( Park Yong Beom ),장승훈 ( Jang Seung Hun ),김동규 ( Kim Dong Gyu ),박 대한결핵 및 호흡기학회 2003 Tuberculosis and Respiratory Diseases Vol.55 No.2
Jun Zou,Jae Bok Lee,Sug Hun Chang IEEE 2009 IEEE transactions on electromagnetic compatibility Vol.51 No.2
<P>It is very essential to calculate the mutual impedance between overhead and buried conductors for analyzing electromagnetic compatibility problems related to a transmission line system. An efficient algorithm for calculating the Pollaczek integral, whose integrand oscillates rapidly and decays slowly, is proposed in this paper. With the help of the asymptotic extraction technique, the Pollaczek integral can be decomposed into the sum of two parts, one of which is expressed with an exponential integral and the other is the one that has a rapidly damped integrand. A comparison of the numerical results with published data shows very good agreement. The proposed approach is a good candidate for calculating impedances related to the Pollaczek integral.</P>
다중 접지계 GPR 수치 해석을 위한 최적 모델링 기법
이재복,장석훈,명성호,조연규,Lee, Jae-Bok,Chang, Sug-Hun,Myung, Sung-Ho,Cho, Yeon-Gyu 한국전자파학회 2006 한국전자파학회논문지 Vol.17 No.11
본 연구는 combined integration/matrix method에 의해 다양한 접지 시스템의 특성을 모의할 수 있는 수치 해석 기법에 관한 연구이다. Combined integration/matrix method는 접지 시스템을 일정한 길이의 요소로 분할하여 미리 적분을 한 후 적분된 길이 요소 기법에 대해 matrix method를 사용하는 방법으로 연산 시간 및 해석시 에러 발생을 줄일 수 있다. 이를 위해 본 연구에서는 수치 해석시 분할 요소 길이에 대한 오차 분석을 통해 최적의 요소길이 산정 방법을 제시하였으며 이를 통해 실규모 접지 시스템의 다양한 형태의 접지 시스템의 성능 분석이 가능하도록 하였다. 오차 분석을 토대로 접지 전극의 길이와 매설 깊이에 따라 적절하게 요소의 길이를 도출한 결과 분할하고자 하는 요소의 길이는 매설 깊이와 접지 도체의 길이에 주요한 상관 관계가 있음을 알 수 있었으며 본 연구에서 제시한 수치 해석 모델링 방법에 따라 3 % 이내의 해석 정확도를 얻을 수 있었다. 또한, 이를 다중 접지계 해석에 적용하여 현재 산업 플랜트 접지 방식에서 가장 논란이 되고 있는 전원 접지계와 신호/통신 접지계의 공통 접지 및 분리 접지의 영향 평가 등에 활용될 수 있음을 보여주었다. This paper describes the numerical analysis techniques using the Combined Integration/Matrix Method to calculate ground potential rise which can be occurred in the various grounding systems. Combined Integration/Matrix Method is used to reduce the error and computation time with the analytical integration equation and the proper segmentaion of earth embedded conductor. To do it, optimal segmentaion method for the buried conductors is presented through error analysis which is capable of applying the practical scaled various grounding systems. The optimum length of segmented element is much co-related with the buried depth of grounding electrode and the maximum length of buried electrode. As a result, less 3 precent errors was obtained by proposed model. The proposed model is applied to verify an effect of multi-grounding problems which was aroused much controversy with separated or common grounding between the high power grounding system and low power grounding system such as signal and telecommunication grounding.
李在福(Jae-Bok Lee),張錫勳(Sug-Hun Chang),明聖鎬(Sung-Ho Myung),趙延奎(Yuen-Gue Cho) 대한전기학회 2008 전기학회논문지 P Vol.57 No.4
There are several ways to bond to building grounding systems for reducing GPR(ground potential rise) and EMI resulting from power system faults or lightning stroke to building. In order to verify effective bonding practice, the GPR and voltage of equipment due to the direct stroke to building are calculated with ATP-EMTP model for transformer, transmission line and MOV(Metal oxide varistor). The simulated model shows a satisfactory accuracy compared with experimental result for the 8/20㎲ simulated current pulse. It is observed that separate grounding can cause dangerous voltage to the building equipment and the performance of surge protective device can improve when it is installed to the protected equipment in distance as short as possible.