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전자파의 집중도를 이용한 바이모달 트램의 전자파 차폐 성능 분석
최낙선(Nak-Sun Choi),정기우(Gi-Woo Jeung),김남경(Nam-Kyung Kim),송명곤(Myung Kon Song),이강원(Kang-Won Lee),목재균(Jai-Kyun Mok),김동훈(Dong-Hun Kim) 대한전기학회 2011 전기학회논문지 Vol.60 No.7
In this paper, the electromagnetic shielding performance of a BiMODAL Tram is investigated by means of an electromagnetic analysis tool, called HFSS. For the purposed of doing this, first, three-dimensional finite element modeling for the tram including electronic devices and engine room is carried out. Then, for quantitatively assessing the electromagnetic shielding performance of the tram’s body, concentration indexes for electric field magnitude and time-average stored electric energy are introduced. From numerical results, it is inferred that the tram’s body can protect the electronic devices and engine room against external electromagnetic waves from 30 ㎒ to 100 ㎒.
2차 전자방출 효과를 고려한 기체방전의 과도상태 유한요소해석
김남경(Nam-Kyung Kim),정기우(Gi-Woo Jeung),최낙선(Nak-Sun Choi),이세희(Se-Hee Lee),김동훈(Dong-Hun Kim) 대한전기학회 2010 전기학회논문지 Vol.59 No.7
To analyze the gas discharge phenomena in parallel-plane electrodes, the fully coupled finite element method (FEM) considering secondary electron emission effects in discharge column was adopted in this paper. Two coupled equations of the hydrodynamic diffusion-drift equations for three carriers and the Poisson’s equation for electric scalar potential should be solved as a system equation. The proposed method including two secondary electron processes of the photoemission and background ionization has been successfully applied to evaluating the breakdown voltage in parallel-plane electrodes and is verified by comparing its numerical results with the experimental ones. From the obtained results, it is inferred that the proposed numerical scheme will be useful for predicting and understanding streamer transient phenomena.
주파수 영역에서 연속체 민감도법을 이용한 유전체 저대역 필터 최적 설계
최낙선(Nak-Sun Choi),정기우(Gi-Woo Jeung),김남경(Nam-Kyung Kim),변진규(Jin-Kyu Byun),김동훈(Dong-Hun Kim) 대한전기학회 2010 전기학회논문지 Vol.59 No.8
This paper presents a new methodology for designing a dielectric waveguide filter with the cutoff frequency of 2.4 ㎓ based on the continuum design sensitivity analysis. An analytical sensitivity formula is derived in frequency domain and then unified program architecture applicable to the optimal design of high-frequency devices is proposed. A three-dimensional dielectric resonator used in waveguide filters has been tested to illustrate the validity of the proposed method.