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Dongil Shin,Sungnam Kim,Geunseok Jeong,Jaesu Park,Joungwook Park,Ki Jin Han,Jingook Kim [Institute of Electrical and Electronics Engineers 2015 IEEE transactions on electromagnetic compatibility Vol.57 No.4
<P>A common-mode (CM) active filter was designed in a compact package to suppress CM conducted emissions at a switching mode power supply (SMPS). Based on the analytical expressions considering both stability and performance, the design and optimization rules for the proposed active filter have been presented. After verifying its performance by measurements using vector network analysis, the proposed filter was installed in a 200-W SMPS board with 64 and 110 kHz switching frequencies, demonstrating its usefulness by experiments. The performance degradation due to the magnetic saturation and the AEF grounding impedance was also analyzed and investigated.</P>
Disk-Loaded 다이폴과 Folded 다이폴로 동작하는 Reconfigurable 안테나
박슬기(Seulgi Park),정근석(Geunseok Jeong),추호성(Hosung Choo),오이석(Yisok Oh) 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.12
본 논문에서는 PIN 다이오드를 사용하여 disk-loaded 다이폴 안테나와 folded 다이폴 안테나로 형상이 변화하는 새로운 구조의 소형 안테나를 개발하였다. 개발된 안테나는 PIN 다이오드의 RF on/off 특성을 이용하여 안테나의 전기적 길이를 변화시켜 이중 대역에서 동작하며, 저주파 대역에서는 높은 복사 저항 값을 가지는 folded 다이폴 안테나로 동작하고 고주파 대역에서는 수평 방향으로 무지향성의 복사 패턴과 수직 방향으로 도넛 형태의 복사 패턴을 가지는 disk-loaded 다이폴 안테나로 동작한다. 제안된 안테나는 20~300 ㎒에서 30 ㎝ 다이폴 안테나에 비해 크기가 소형화 되었음에도 높은 이득을 가진다. 또한, 300~1,300 ㎒에서 80° 이상의 넓은 빔 폭을 가짐으로써 방향 탐지 안테나로 사용이 가능하다. In this paper, we propose a reconfigurable antenna which operates as a disk-loaded dipole antenna and a folded dipole antenna alternatively using RF on/off switches. The antenna can change its effective length to achieve dual-band operation; operates as the folded dipole antenna for stepping up the radiation resistance in low frequency band of 20~300 ㎒, and as the disk-loaded dipole antenna for an omni-directional radiation pattern (horizontal plane) and a donut-shaped radiation pattern (vertical plane) in high frequency band of 300~1.3 ㎓. In the low band, the proposed antenna shows higher gain than a conventional dipole antenna with a reduced antenna size. In the high band, the antenna maintains a broad beamwidth of about 80°, thus the antenna can be applicable to antennas for direction finding applications.
Common Mode Noise Reduction for an LLC Resonant Converter by Using Passive Noise Cancellation
Younggon Ryu,Sungnam Kim,Geunseok Jeong,Jaesu Park,Duil Kim,Jongwook Park,Jingook Kim,Ki Jin Han 한국전자파학회JEES 2015 Journal of Electromagnetic Engineering and Science Vol.15 No.2
This paper describes the application of a passive noise cancellation method to a prototype inductor-inductor-capacitor (LLC) resonant converter by placing a compensation winding in a transformer to reduce common mode noise. The connection method for the compensation winding is investigated. A circuit analysis is implemented for the displacement currents between the primary and secondary windings in the transformer. The analyzed displacement currents are verified by performing a circuit simulation and a proper compensation winding connection that reduces common mode noise is found. The measurement results show that common mode noise is reduced effectively up to 20 dB in the 1 to 7 MHz frequency region for the prototype LLC resonant converter by using the proposed passive noise cancellation method.