• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.179-182
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• 2003

A simulation on bootstrapping circuit has been performed by modelling a coaxial cable as a transmission line. It is shown that the bootstrapping circuit could be unstable due to the transmission line effect though an ideal amplifier is used. While the conventional bootstrapping circuit does not cancel the input capacitance of the input buffer, a new bootstrapping circuit that cancels input capacitance of the input buffer has been proposed. The proposed bootstrapping circuit consists of the input buffer of which gam is larger than 1 and a feedback resistor to control the loop gain. The proposed bootstrapping circuit has higher input impedance than that of the conventional circuit.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.323-325
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• 1997

Conventionally it is asummed that the microstrip line conductor has a rectangular cross-section. but the additive and substactive processes used to create conductors for PCBs produce a conductor of approximately Trapezoidal cross-section. For wide Strip line, the thickness and edge effect will be small since most of capacitance is parallel plate rather than fringing and we can ignore the cross-section. For narrow strip lines, the edge effect become immportant. So in this paper, we measure the chracteristic impedance of microstripline by Vector Analyzer and simulate the electromagnetic field of microstripline using finite element method with edge angle.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.220-223
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• 1998

We have performed an EMTDC simulation for the current limiting effects of a superconducting fault current limiter (SFCL) for the 154 kV transmission line between the Gaepo and Sungnam substations. The fault current increased up to 39 kA during an artificial ground fault. The SFCL with 100 ${\Omega}$ impedance after quench limited the current to 15 kA within a half cycle. This limited current is well below the upper limit of a circuit breaker, suggesting that the impedance of the SFCL in the transmission line is sufficient.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.196-197
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• 2006

An effective method is described for monitoring the ground impedance of intelligent building and power system. Most of grounding system of buildings are interconnected to extensive grounding network of power line, signal and control line, telecommunication line, and etc. Therefore, the residual voltages of power frequency and its harmonics may have an significant influence on the accurate measurement of ground impedance. For eliminating the influence of residual voltage, we developed a test power source for generating the 110[Hz] square wave and used digital filtering method in this research.

• 전기학회논문지
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• 제61권9호
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• pp.1300-1305
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• 2012

A triaxial Blumlein pulse forming line has been designed to generate a pulse whose voltage is ~300 kV, pulse duration is ~5 ns, and rise time is ~500 ps. It turns out, however, that the rise time of the pulse becomes much longer than 500 ps due to parasitic inductances and capacitances existing inside the system. A peaking switch has been developed to shorten the rise time of the pulse from Blumlein pulse forming line. In the peaking switch, a wedge-shaped dielectric material (MC 901 nylon) is employed to surround the electrode on the antenna side. This shape inhibits an abrupt change of the output impedance, thereby minimizing the reflection of the output pulse. Experimental results show that the peaking switch is capable of improving the rise time of the pulse at a level of 500 ps.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권1호
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• pp.40-44
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• 2006

In this paper, the distortion characteristics of an electrical pulse which has a rise/fall time due to the dispersion and the reflection, on nonuniform tapered microstrip lines has investigated in time domain. The transmission characteristics on uniform microstrip lines in time domain had represented already, but the results for the nonuniform tapered microstrip lines not represented yet. We investigated the transmission characteristics for pulse signal on the nonuniform tapered microstrip lines, and the result applied to design of wide band impedance matching circuit in design of MMIC. The voltage and current transfer functions are shown for the tapered line. The dispersion and distortion obtained by using these transfer functions are represented for the nonideal square pulse.

• Journal of Advanced Marine Engineering and Technology
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• 제36권1호
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• pp.149-156
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• 2012

본 논문에서는 기존의 PACD (Periodically Arrayed Capacitive Devices) 선로구조가 가지는 고 손실 특성의 문제점을 개선하기 위하여, 단파장 특성이 있는 Inverted PACD 구조를 제안하였다. Inverted PACD 선로구조의 손실특성은 종래의 PACD 구조와 비교하여 훨씬 개선되었으며, 구체적으로 ${\lambda}$/4의 길이를 가지는 Inverted PACD 선로구조의 손실특성은 4GHz에서 0.41dB이다. 그리고 상기 Inverted PACD 선로구조는 종래의 마이크로스트립 선로보다 단파장 특성을 보여주었으며, 구체적으로 종래의 전송선로 파장의 11.85%로 파장이 대폭 축소되었다. MMIC용 초소형 수동소자로서의 응용가능성을 제시하기 위하여, Inverted PACD 선로구조를 이용하여 GaAs MMIC상에 임피던스 변환기를 제작 및 측정하였다. 그 결과 Inverted PACD 선로구조를 이용하여 제작한 임피던스 변환기의 크기는 0.012 $mm^2$이며, 종래의 임피던스 변환기 크기의 1.7%의 면적을 차지하였다. 상기 임피던스 변환기는 2.25~6.5GHz 대역에서 -10dB 이하 반사손실과 -1dB이하의 삽입손실 등 양호한 RF 특성을 보여주었다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.283-287
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• 2003

A new method to miniaturize ${\lambda}/4$ transmission line of power divider is proposed. The method utilizes simple combination of the shorted coupled-line pair instead of the transmission line with very high impedance and shunt lumped capacitors. The length of ${\lambda}/4$ transmission line of power divider is about 16% over the conventional power divider at 1 GHz.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1426-1430
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• 2009

AC AT feeding method consists return circuits of electric train inserting in parallel between trolly line and feeding line and connecting neutral line to rail and FPW. Due to increasing electric load at feeding system, collecting voltage of train and end voltage are going down. So to increase voltage between trolly line and rail, the usefulness of new autotransformer are considered which variation of short impedance and change of line voltage is simulated with modified winding ratio of autotransformer from 1:1 to variable tab.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.1301-1304
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• 2005

본 논문에서는 전력선 통신 시스템에서 급격하게 변화는 임피던스 때문에 발생하는 에러율을 개선하기 위하여 제안한 D급 증폭 구동 회로를 적용하였다. 전력선 모뎀에, 일반적인 구동회로인 전압 구동 회로와 전류 구동 회로를 제작하여 실험을 하였다. 그리고 같은 전력선 모뎀에 본 논문에서 제안한 D급 증폭 회로를 이용한 구동 회로를 사용하여 실험을 하였다. 실험 결과 본 논문에서 설계한 구동 회로가 전력선 통신에서 임피던스 변화에 대하여 다른 구동 회로보다 성능이 우수함을 보였다.