• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.587-590
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• 2005

We investigated the input impedance characteristics of UHF-band RFID tag chip for increased reading range. A voltage multiplier designed using 0.4 ${\mu}m$ $zero-V_T$ MOSFET showed that DC output voltage of 2 V can be obtained using standard CMOS process. The input impedance of the voltage multiplier was examined to achieve impedance level for maximum reading distance using analytical and numerical approaches. The input impedance of the voltage multiplier could be varied in a wide range by selecting the size of MOSFET and the number of multiplying stages of the voltage multiplier, and thus, the impedance level required for the tag antenna can be obtained in presence of other tag circuit blocks.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.35-38
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• 2005

In this paper, a wideband balun of tapered structure using planar microstrip is desigde ad analyzed. The balun structure was fabricated on a Teflon substrate with a thickness of 0.8mm and relative dielectric constant ${\varepsilon}_r$ of 2.5. Two back-to back CPW-to-CPS transitions were simulated and optimized using HFSS. A movel plaar balun using tapered structure of microstip to CPW is suggested and designed. The measurement result, the bandwidth for a reflection coefficient better than -10dB of the balun is 2GHz to 8GHz. The planar balun can improved the performance of wide band spiral antenna.

• 한국통신학회논문지
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• 제31권3C
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• pp.279-285
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• 2006

초광대역 무선 통신에서 불규칙 각도 퍼짐이 발생하는 초광대역 옥내 환경에 적합한 새로운 신호 모형을 제안하고 군집된 초광대역 신호의 도착 방향(AOA)을 추정한다. 제안된 모형에 적합한 부공간 추정기법을 적용하여 수신된 초광대역 군집 신호의 신호 도착 방향과 퍼짐모수의 추정치를 얻는다. 제안된 모형과 추정기법은 컴퓨터 모의실험으로 검증되며 추정 오차의 성능도 분석한다.

• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.901-906
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• 2007

In this study, we measured the partial discharge phenomenon of inside the closed switchgear, using ultra wide band antenna. The characteristics of $\Phi-q-n$ in the normal state are stable, and confirmed at less than 0.01, but in proceeding states, about 2 times larger. And in the abnormal state, it grew hundreds of times larger compared with normal state. According to K-means analysis, if slant of discharge characteristics is a straight line close to "0" and standard deviation is small, it is in a normal state. However if we can find a peak from K-means clusters and standard deviation to be large, it is in an abnormal state.

• 대한전자공학회논문지
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• 제20권3호
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• pp.40-44
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• 1983

원판형 마이크로스트립 패치를 기본 소자로 하여 준 대수 주각형 광대역 마이크로스트립 안테나를 설계한다. 각 방사소자들은 종단이 개방된 주급전 마이크로스트립 선로상에서 정합선로를 통하여 직열 급전된다. 설계 제작된 안테나의 정재파비는 주파수 2.72∼3.43GHz 범위내에서 약 2.3이하로 됨이 실험적 결과로 나타났다.

• 한국항해학회지
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• 제22권2호
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• pp.39-45
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• 1998

CATV(Cable Television) 및 MATV(Master Antenna TV) 시스템용 신호분기기(Tap-Off)의 광대역설계법을 새로운 방법으로 제안한다. 먼저 결합선로형 방향성결합기의 이론을 도입하여 변성기형 방향성결합기에 적용하여 해석하였다. 제안한 해석방법의 타당성을 입증하기 위하여 시뮬레이션한 결과와 실험결과를 비교 검토하였고 전송선로의 임피던스를 매칭시켜 반사계수 20dB, isolation 25dB(5∼1600MHz)을 만족하는 신호분기기(14dB)의 광대역화(5∼2150MHz)를 실현하였다.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권6호
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• pp.224-229
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• 2003

An ultra high frequency (UHF) coupler possessing ultra wide band (UWB) characteristics ranging from hundreds of MHz to several GHz is desirable for the detection of the partial discharge (PD) pulses because the pulses propagate with rise time shorter than one nanosecond in a gas-insulated substation (GIS). Thus, the authors have proposed a log-periodic antenna for GIS PD detection. Various parameters of the coupler such as frequency bandwidth, coupler gain, radiation pattern, and coupler geometry were considered throughout the simulations. The experiments for the detection characteristics of the coupler were carried out in the mock-up GIS chamber. The results indicated that the detection characteristics of the coupler are dependent on the installation angle of the coupler, the position of the coupler in the hand hole and the existence of the spacer.

• 제어로봇시스템학회논문지
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• 제12권12호
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• pp.1231-1234
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• 2006

In this study, we detected electromagnetic waves generated in an enclosed switchgear and applied various statistical methods for detecting signals. We calculated the various statistical factors via the appropriate statistical methods. Further, we used these statistics to recognize the characteristics for each pattern by identifying the partial discharge in each case for normal, proceeding and abnormal states. The characteristics of electromagnetic wave patterns occurred in various states at electric power facilities and were used as an output variable for more efficient diagnosis. In this paper, we confirmed that the pattern of partial discharge signal can be used as one of the factors used to analyze the insulation state and to consider while estimating diagnosis of insulation states by recognizing the signal pattern to intelligence. We will utilize the proposed diagnosis method to determine insulation degradation states.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권12호
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• pp.597-600
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• 2006

When the energy of the nanoseconds high voltage pulse with hundreds picoseconds of the pulse rise time is emitted into the free space via an antenna, an ultra wide band electromagnetic wave is generated. This electromagnetic wave is expected to be used in transmitting vast amount of informations to far distance, high performance radars, post-packaging pasteurization of food, the detection of underground buried objects, searching of underground water veins or caves, the treatment of waste water or polluted gases and so forth. Additionally, this technology can be used in EMI(electromagnetic interference) evaluation of measuring instruments or printed circuit boards.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1776-1778
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• 2003

Partial Discharge(PD) pulses propagate in gas insulated substation(GIS) with rise time shorter than one nanosecond. Therefore, Ultra high frequency(UHF) couplers which have ultra wide band(UWB) characteristics from hundreds of MHz to several GHz are desirable for the detection of the PB pulses in GIS. In this paper, the authors proposed a log-periodic antenna for GIS PD detection. Various parameters of the coupler such as frequency bandwidth, coupler gain, radiation pattern, coupler geometry were considered through the simulations and the experiments together.