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전자장 해석을 통한 매트릭스형 한류기용 리액터 설계 및 특성해석
정동철(Dong-Chul Chung),윤창훈(Chang-Hun Yun),최효상(Hyo-Sang Choi) 대한전기학회 2009 전기학회논문지 P Vol.58 No.2
In this paper, we performed the optimum design of reactors for matrix-type superconducting-fault current limiters (SFCLs), using electromagnetic analysis tools. We decided a optimun position within a reactor for superconducting elements of current-limiting parts and trigger parts from the calculation of magnetic flux internsity for reactor structures. Also we decided effective distance length between two reactors through the analysis of the distribution of magnetic field, according to distance lengths between them. We designed and characterized matrix-type SFCLs, based on our optimum design of a reactor. We confirmed uniform distribution of a fault current, resulted from the improvement of simultaneous quench characteristics within our matrix-type SFCL.
고온초전도체를 이용한 마이크로파 전력분배기의 소형화 개발
정동철(Dong-Chul Chung),유병화(Byung-Hwa Yoo),곽민환(Min-Hwan Kwak),강광용(Gwang-Yong Kang),한병성(Byoung-Sung Han) 대한전기학회 2009 전기학회논문지 P Vol.58 No.3
In this paper, We report the miniaturization of superconducting microwave power dividers based on lumped element equivalent circuits. To do this, we analyzed a conventional branch-type power divider by using an ABCD matrix under even and odd mode excitation. Then, we calculated each lumped element impedance throughout this analysis of a transmission line matrix. Also we simulated our equivalent circuits made of lumped elements by using a full wave analysis, em Sonnet. Our deign of microwave power divider based on simulated results was fabricated on high-Tc superconducting thin films deposited on MgO substrate. Experimental results were reported in terms of bandwidth, center frequency, and phase difference between S21 and S31. We confirm that our design will be useful in the future microwave power systum.
고온초전도체를 이용한 가지 형태 3 ㏈ 방향성 결합기 설계 및 특성해석
정동철(Dong Chul Chung),최명호(Myoung Ho Choi) 대한전기학회 2010 전기학회논문지 Vol.59 No.1
In this work, we presented the characterization of 3 ㏈ branch type directional couplers by using High-Tc superconducting thin films. To do this, we deposited YBCO superconducting thin films on MgO substrates by using rf-magnetron sputtering techniques. The designed center frequency was 408 MHz and the designed passband was 20 ㎒. Also we designed 3 ㏈ Power difference and 90° of phase difference between port 3 and port 4. The even and odd mode analysis were used to characterize our directional couplers and em Sonnet (full wave analysis program) was utilized to the optimum design. We reported experimental results, including a center frequency, passband, half power characteristics and phase differences. We confirmed that experimental results were in good agreements with characterization by using full wave analysis program.
개구결합을 이용한 H 형태 초전도 안테나의 제작 및 특성 해석
정동철,한병성,유기수,이종하,석중현,이은홍,Chung, Dong-Chul,Han, Byoung-Sung,Ryu, Ki-Su,Lee, Jong-Ha,Sok, Jung-Hyun,Lee, Eun-Hong 대한전자공학회 2000 電子工學會論文誌 IE (Industry electronics) Vol.37 No.1
"H" 형태의 공진기로서 이루어진 초전도 안테나는 비슷한 크기를 가진 마이크로스트립 안테나에 비하여 소형화에 유리하다. "H"형 초전도 안테나 제작을 위해 rf 마그네트론 스퍼터링을 이용하여 $YBa_2Cu_3O_{7-x}$ (YBCO)/MgO 고온초전도 박막을 제조하였으며 표준 식각법을 이용하여 안테나를 형상화 하였다. 일반 금속과의 특성을 비교하기 위해서 동일한 차원의 금 안테나가 제작되었다. 개구 결합 방식을 이용하여 초전도 안테나 패치와 $50{\Omega}$ 급전선을 임피던스 결합을 시켰다. 다양한 종류의 실험 결과가 반사손실, 공진주파수, 특성임피던스 등을 중심으로 보고되었다. H형 초전도 안테나는 금 안테나에 비하여 정재파비에서 0.36 효율에서 24% 반사손실에서 14.6bB 이상 더 우수한 성능을 보여주었다. The high-$T_c$ Superconducting (HTS) antenna which consists of "H" type resonator has the benefits for the miniaturization of antenna in comparison with the microstrip antenna of the similar dimension. To fabricate the "H" type antenna, HTS $YBa_2Cu_3O_{7-x}$ (YBCO) thin films were deposited on MgO substrates using rf-magnetron sputtering. Standard etching processes were performed for the patterning of the "H" type antenna. For comparison between normal conducting antennas and superconducting antennas, the gold antennas with the same dimension were also fabricated. An aperture coupling was used for impedance matching between $50{\Omega}$ feed line and HTS radiating patch. The diverse experimental results were reported in terms of the resonant frequency, the return loss and the characteristics impedance. The "H" type superconducting antenna showed the performance of 1.36 in SWR, 24% in efficiency, and 14.6 dB in the return loss superior of the normal conducting counterpart.
삼선 지락사고 발생시 매트릭스형 한류기용 리액터의 전자장 분포 해석
정동철(Dong Chul Chung),한태희(Tae Hee Han) 대한전기학회 2011 전기학회논문지 Vol.60 No.2
In this paper we reported the characteristics of 1 line, 2 lines and 3 lines-to-ground fault of matrix-type SFCLs (MFCLs) and the electromagnetic field distribution of reactors for MFCLs under the same cases of ground faults. To do this, we fabricated MFCLs with 6 reactors for 3 phases. Each reactor had the length of 270 ㎜ and diameter of 80 ㎜. 6 reactors were made by Bakelite. We reported experimental results, including fault currents, fault voltages and magnetic field distribution according to phase differences between each phase. We confirmed that experimental results will be useful in next future plan for real power grid.
직접삽입 급전 방식을 이용한 고온초전도 마이크로스트립 안테나의 제작 및 특성 해석
정동철,한병성,김진,유기수,홍석용,이종하,Chung, Dong-Chul,Han, Byoung-Sung,Kim, Jin,Ryu, Ki-Su,Hong, Suck-Yong,Lee, Jong-Ha 대한전자공학회 2000 電子工學會論文誌 IE (Industry electronics) Vol.37 No.1
초전도체를 초고주파 소자에 응용하려고 할 경우, 초전도 전자기학의 불확실함이나 초전도 기판의 돈도 의존성은 산업 응용을 위한 안테나를 제작하는데 있어 어려움을 준다. 따라서 실제 응용을 위해서는 일반 안테나와 비교하여 정확하고 자세한 특성이 알려져야만 한다. 본 논문에서는 금 안테나와 초전도 안테나의 비교 연구를 수행하였으며 반사 손실, 특성임피던스, 효율 및 다른 다양한 특성들을 보고하였다. 본 연구에 사용된 고온초전도 박막은 $YBa_2Cu_3O_{7-x}$ (YBCO)/MgO 이며 초전도 안테나는 마이크로스트립 급전선을 방사 패치의 50 ${\Omega}$ 영역에 결합시키는 형태로 만들어졌다. 금 안테나와 초전도 안테나의 측정 결과는 이러한 구조를 이용하여 유용한 안테나가 제작될 수 있음을 보여주었다. In applying high-${\underline{T_c}}$ superconducting material to microwave devices, Uncertainty of electromagnetics of high-${\underline{T_c}}$ superconductor(HTS) and the temperature dependence of the substrate fits with HTS thin film cause difficulty in realization of such antenna for industrial applications. It must be noted to characteristic the HTS antenna in contrast with normal conducting counterpart for this real application. In this paper, a comparative study between HTS microstrip antennas and gold antennas was reported in terms of the return loss, the characteristic impedance, efficiency, and other various characteristics. HTS thin films were $YBa_2Cu_3O_{7-x}$ (YBCO) on MgO substrates. Superconducting microstrip antennas used in this work were to directly inset a microstrip transmission line into the 50 ${\Omega}$ region of the radiating patch. Measurement results of HTS antennas and gold antennas showed that usable antennas can be made using this architecture.
정동철(Dong Chul Chung) 대한전기학회 2012 전기학회논문지 Vol.61 No.12
In this work, we investigated quench characteristics of matrix-type superconducting fault current limiters (MFCLs) according to the turn number of reactors. The reactors used in MFCLs apply magnetic field to superconducting elements within reactors when fault currents surge into MFCL systems. It makes the fast and simultaneous quenches between superconducting elements. Also reactors decrease the fault power burden of superconducting elements by bypassing the partial fault currents to itself, when quench occurs. These structure proposed in this work can be expected to achieve much more current limiting capacity even though it uses less superconductors compared with other type SFCLs. Three reactors were made by Bakelite. These reactors with the turn number of 190, 380 and 570, had the length of 270 mm and diameter of 80 mm. We reported experimental results, including fault currents, fault voltages and resistance in superconducting elements according to the turn number of reactors. We confirmed that experimental results will be useful in next future plan for the real power grid.