• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.281-283
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• 2008

The superconducting fault current limiter (SFCL) using magnetic coupling of two coils with series connection, which was suggested by us, has the merit to increase the operational current and the limiting impedance of the SFCL through the adjustment of the inductance ratio and the winding direction of two coils. In addition, the recovery characteristics of the SFCL is affected by the winding direction of two coils as well as two coils' inductance ratio. In this paper, the fault current limiting and recovery characteristics of a SFCL using magnetic coupling of two coils with series connection were analyzed. Through the analysis based on the experimental results, the recovery characteristics and the current limiting characteristics of the SFCL were confirmed to be improved more in case of the additive polarity winding.

• 전기학회논문지
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• 제59권7호
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• pp.1282-1288
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• 2010

This paper proposes a novel microstrip patch antenna to make impedance matching possible by using slot/T-slot capacitive coupling between the patch and 50 $\Omega$ feed line on a ground plane. The single band/linear polarization patch antenna shows linear polarization at 2.4 GHz band. Under -10 dB return loss, the single band/linear polarization patch antenna obtains 50 MHz bandwidth at 2.37 GHz~2.42 GHz. The dual band/dual polarization microstrip patch antenna shows circular polarization at 2.4 GHz band and linear polarization at 3.1 GHz band. Under -10 dB return loss, The dual band/dual polarization microstrip patch antenna obtains 340 MHz bandwidth at 2.23~2.57 GHz and 375 MHz bandwidth at 2.95~3.325 GHz.

• 한국음향학회지
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• 제37권1호
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• pp.46-52
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• 2018

압전변압기에 사용되는 압전 단결정은 높은 입력 임피던스로 인하여 파워전송용량이 높지 않다는 문제점이 있다. 따라서 본 연구에서는 연산증폭기를 사용한 범용 임피던스 변환(General Impedance Convert, GIC) 회로로 구현된 정전용량 증가회로를 압전 단결정 진동자의 전기단자에 연결함으로써 입력임피던스를 저하시켜 파워전송용량을 향상시킬 수 있는 방법을 제안하였다. $128^{\circ}$회전 Y판 $LiNbO_3$ 단결정 진동자에 설계 제작된 정전용량 증가회로를 적용하여 구동 특성을 측정한 결과, 입력임피턴스는 25 % 감소, 전기-기계결합계수는 30 % 증가, 전압변환 특성에 있어서는 약 17~30배의 출력파워용량이 증가됨을 확인하였다.

• 한국전기전자재료학회논문지
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• 제25권12호
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• pp.949-954
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• 2012

The K-PCS and W-CDMA dual band dielectric duplexer and bandpass filters have been designed and fabricated. The dual band duplexer consists of the separate monoblock K-PCS and W-CDMA duplexers using common antenna port. The coupling capacitance and I/O impedance matching have been designed to minimize the cross interference between the bands. Isolations of crosspoint between Tx and Rx in K-PCS and W-CDMA dualband were about 47 dB and 100 dB, respectively. On the other hand, isolations of Tx and Rx in K-PCS and W-CDMA were about 66 dB and 65 dB, respectively. The difference between 47 dB and 100 dB originated from the different center frequencies in Tx and Rx of K-PCS and W-CDMA bands. The coupling capacitance of the bandwidth, I/O capacitance of I/O matching and impedance matching, and various capacitances were important role to fabricate the dielectric duplexer and bandpass filters.

• 한국전자파학회논문지
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• 제26권5호
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• pp.499-505
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• 2015

전자기 공진 현상을 이용한 무선전력전송 시스템에 대한 조사량 평가 시 전기장의 고려 여부를 검토하였다. 인체로 인가되는 전기장과 자기장의 상대적인 크기가 조사량 평가 시에 중요한 지표가 되기 때문에, 이를 검토하기 위해 자기 다이폴 인근의 다양한 전자기장의 크기를 갖는 곳에 구형의 간이 인체 모델을 위치시키고, 구 모델 내부로 유도되는 전기장의 값을 이론과 수치해석을 통하여 구하고 비교하였다. 그 결과, 전기장을 무시할 수 없는 영역이 존재함을 확인하였으며, 이는 무선전력전송의 조사량 평가 시 외부 전기장에 대한 고려가 필요함을 알 수 있었다.

• 한국소음진동공학회논문집
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• 제14권8호
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• pp.718-725
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• 2004

If a wall separates the bounded and unbounded spaces, then the wall’s role in transporting the acoustic characteristics of the two spaces is not well defined. In this paper, we attempted to see how the acoustic characteristics of two spaces are really affected by the spatial characteristics of the wall. In order to understand coupling mechanism, we choose a finite space and a semi-infinite space separated by the flexible or rigid wall and an opening. A volume interaction can be occurred in structure boundary and a pressure Interaction can be happened in the opening boundary. For its simplicity, without loosing generality, we use rather simplified rectangle model instead of generally shaped model. The source impedance is presented to the various types of boundaries. The distributions of pressure and active intensity are also presented at the cavity- and structure-dominated modes. The resulting modification, shifts of modal frequencies and changing of standing wave patterns to satisfy both coupled boundary conditions and governing equations, are presented.

• Journal of electromagnetic engineering and science
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• 제14권2호
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• pp.54-60
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• 2014

A systematic design for asymmetric coupled-section Marchand baluns is presented. Asymmetrically coupled transmission lines in multilayer configuration are exploited for constructing Marchand baluns. Design equations for characteristic impedance and electrical length of asymmetrical coupled transmission lines are derived for establishing a systematic design procedure. Novel Marchand balun based on these design equations is composed of two identical asymmetrical coupled transmission lines. However, contrary to the general conventional design approach where ranges for characteristic impedances of coupled lines are ambiguously capitalized, values for characteristic impedance and length are explicitly expressed. Our approach is fundamentally different from the design method using coupling coefficients where solution for coupling coefficient is inherently restricted. To verify the proposed method, one design example is performed for wideband Marchand balun in multilayer configuration, and is fabricated for verifying the design procedure proposed. Maintaining the return loss more than 10 dB, the bandwidth is measured from 0.43 to 1.0 GHz, where $S_{21}$ and $S_{31}$ show better than -4 dB. The measured phase and amplitude imbalances illustrate 0.5 dB and ${\pm}5^{\circ}$, respectively.

• 한국음향학회지
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• 제13권2호
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• pp.60-67
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• 1994

본 논문은 두 편으로 연결된 논문의 첫 논문으로 무한음향 매질내의 축대칭음향 변환기 음향특성 해석을 위한 유한요소법과 하이브리드형 무한요소법의 결합 알고리즘을 제시하고 이를 이용한 음향변환기의 방사 임피던스, 지향성 및 압전자간의 결합 효과에 대한 수치해석 결과를 제시하였다. 두번째 논문에서는 첫논문의 결과를 기초로 광대역 배역 변환기를 설계하고 설계된 변환가의 음향특성을 해석하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1408-1409
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• 2006

In this paper, poly methyl methacrylate thin films were deposited on a ITO glass substrate using a plasma polymerization technique. In order to investigate the influence of the plasma coupling method and plasma conditions on the plasma polymerized poly methyl methacrylate (ppMMA) thin film properties, inductively coupled (ICP) and capacitively coupled plasma (CCP) were used to generate the plasma and the plasma parameters were varied. Molecular structures of the ppMMAs were investigated using a Fourier Transform Infrared (FT-IR) spectroscopy. Dielectric constants of the ppMMA thin films were investigated using a impedance analyzer (HP4192A, LF Impedance Analyzer). Current-Voltage (I-V) characteristics of the ppMMA thin films were investigated using a source measurement unit (SMU: Keithley 2400). Relationship between the plasma coupling technique/process parameter and ppMMA thin films properties were investigated.

• 한국전자파학회논문지
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• 제21권1호
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• pp.36-45
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• 2010

본 논문에서는 가전기기 등에 무선으로 전력을 전송하는 것을 목표로 루프 안테나를 이용한 무선 전력 전송 시스템의 새로운 설계 방법을 제안하였다. 본 설계 방법은 복잡한 전자기 시뮬레이션 없이 간단한 결합 계수의 측정과 루프 안테나의 등가 회로 모델에 대한 근사식만으로 무선 전력 전송 시스템을 설계할 수 있다. 본 논문에서 제시한 설계 방법에 따라 13.56 MHz에서 동작하는 $50{\times}50\;cm^2$ 크기를 갖는 루프 안테나 쌍을 설계하고, 거리에 따른 입력 반사 계수, 결합 계수, 효율 및 임피던스 변화를 측정하였다. 측정 결과, 본 논문에서 제안한 설계 방법이 입력 임피던스 특성을 정확하게 예측할 수 있음을 확인하였다. 또한 50 cm 이하의 거리에서 본 논문의 설계 방법을 이용하여 임피던스 정합한 무선 전력 전송 시스템이 일반적인 $50\;{\Omega}$ 임피던스 정합 회로를 갖도록 설계된 경우보다 효율이 2배 정도 개선되는 것을 확인하여 제안한 설계법의 유용성을 확인하였다.