• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.501-505
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• 2001

The parallel operation system of UPS is used to increase reliability of power source at critical load. But parallel UPS system has a few defects, impedance is different from each other and circulating current occurs between UPSs, due to line impedance and parameter variation, though controlled by the same synchronization signal. According to such characteristic of parallel UPS, balanced load-sharing control is the most important technique in parallel UPS operation. In this paper, a novel power deviation compensation algorithm is proposed. it is composed of voltage controller to compensate power deviation that be calculated by using active and reactive current deviation between inverters on synchronous d-q reference frame.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.661-663
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• 1996

The thyristor controlled series compensator can vary the impedance continuously to levels below and up to the line's natural impedance, thus enabling transmission line capability to be increased and power flow to be controlled. The dynamic performance of TCSC to increase the power system damping is mainly analyzed in this paper. The TCSC controller used here is of the PID type and the input signal to the controller is the active power flow through the TCSC. The TCSC parameters are determined so as to minimize the modal performance measure for duping of power system oscillations.

• 한국군사과학기술학회지
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• 제9권2호
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• pp.136-142
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• 2006

A damped sinusoidal electromagnetic pulse generator was designed, fabricated and tested. The pulse generator consisted of an oscillator(a spark gap switch and an initially charged low impedance line) and a high impedance antenna. This generator was capable of producing damped sinusoidal pulses at closure of the spark gap switch. A Marx generator was employed to supply the Pulse generator with high voltage pulses. While the pulse generator was provided with the high voltage pulses of 200kV from the Marx generator, its output power was maximized by controlling the pressure of the gas contained in the spark gap switch. The output power of the damped sinusoidal electromagnetic pulse oscillator was 1.3GW and the amplitude of electric field radiated from the pulse generator was 4kV/m at the range of 25m.

• Journal of Advanced Marine Engineering and Technology
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• 제32권2호
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• pp.330-335
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• 2008

In this study, highly miniaturized short-wavelength transmission line employing periodically perforated ground metal (PPGM) structures were developed for application to miniaturized on-chip passive component on Si RFIC. The transmission line employing PPGM structure showed shorter wavelength and lower characteristic impedance than conventional coplanar-type transmission line. The wavelength of the transmission line employing PPGM structure was 57% of the conventional coplanar-type transmission line on Si Radio Frequency Integrated Circuit (RFIC) substrate. Basic characteristics of the transmission line employing PPGM structure were also investigated in order to evaluate its suitability for application to a development of miniaturized passive on-chip components. According to the results, it was found that the PPGM structure is a promising candidate for application to a development of miniaturized on-chip passive components on Si RFIC.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권8호
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• pp.368-374
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• 2002

In this paper, we introduce a procedure to obtain a equivalent circuit of comb-line band pass filter. By employing equivalent circuits of each asymmetrical coupled line. we composed the full equivalent circuit of comb-line bandpass filter and derived simple design equations for extracting each line's impedance. To show the validity of design equations, we simulated and fabricated a planar type comb-line bandpass filter, which has center frequency 1.8㎓, band-width 50㎒ and four resonators. The resulting filter is very compact, have broad stop band with the second pass band centered at four times the center frequency of the first pass band. The experimental results show exact performances of design specification.

• 한국전기전자재료학회논문지
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• 제15권1호
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• pp.85-92
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• 2002

In this study, we analyzed and experimented micro-strip line inductors and capacitors for a SAW duplexer, an important devise for mobile communication. For SAW duplexers, micro-strip line lumped elements must have small impedance values, below several tens of nH or several tens of pF, and a small area pattern. In this study, we performed theoretical analysis of flat line type, meander line type, and spiral line type inductors and interdigital capacitors on a LiTaO$_3$ Piezo-crystal. We proposed a measurement method to evaluate small values of lumped elements accurately with network analyzer. In experiments, we confirmed validity of the theoretical analysis method through fabrication and characterization of micro-strip line lumped elements. The analysis method in this paper can be applied to SAW duplexers well as other microwave devices.

• 동력기계공학회지
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• 제13권2호
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• pp.71-82
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• 2009

This paper presents a real-time haptic rendering method for a realistic force feedback in a remote environment with varying communication time-delay. The remote environment is assumed as a virtual environment based on a computer graphics, for example, on-line shopping mall, internet game and cyber-education. The properties of a virtual object such as stiffness and viscosity are assumed to be unknown because they are changed according to the contact position and/or a penetrated depth into the object. The DARMAX model based output estimator is proposed to trace the correct impedance of the virtual object in real-time. The output estimator is developed on the input-output relationship. It can trace the varying impedance in real-time by virtue of P-matrix resetting algorithm. And the estimator can trace the correct impedance by using a white noise that prevents the biased input-output information. Realistic output forces are generated in real-time, by using the inputs and the estimated impedance, even though the communication time delay and the impedance of the virtual object are unknown and changed. The generated forces trace the analytical forces computed from the virtual model of the remote environment. Performance is demonstrated by experiments with a 1-dof haptic device and a spring-damper-based virtual model.

• 대한전자공학회논문지TC
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• 제49권2호
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• pp.39-49
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• 2012

병렬 스터브를 이용하여 개구면 결합 마이크로스트립 패치 안테나 (ACMPA)의 임피던스 대역폭을 넓히는 방법에 대해 연구하였다. H-모양의 개구면을 가지는 일반적인 ACMPA를 설계하고 등가회로의 전기적 파라미터를 추출하였다. 급전선로에 병렬 스터브를 삽입하여 ACMPA의 임피던스 대역폭을 확장시키는 방법을 제시하였다. 병렬 스터브를 삽입한 ACMPA의 -10dB 임피던스 대역폭은 최대 약 14 %로 일반적인 ACMPA의 최대 임피던스 대역폭 5.4 %와 비교하여 대역폭이 약 160 % 증가함을 볼 수 있었다.

• 전자공학회논문지D
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• 제35D권10호
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• pp.67-75
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• 1998

본 논문에서는 MCM 배선의 특성 임피던스를 제어하는 마이크로스트립의 기하학적 변수에 대해 조사하였고, 50MHz 주파수와 비교하여 500 MHz 주파수에서 전송감쇠, 전송지연, 누화 등을 계산하여 배선의 실제적인 요구조건으로 MCM-L과 MCM-D 배선의 임계길이를 평가하였다. 특성 임피던스 50 을 갖는 MCM-L 과 MCM-D 배선의 실례를 통해, 마이크로스트립의 특성 임피던스를 제어하는데 가장 중요한 변수는 유전체의 두께와 배선의 폭임을 알 수 있었다. 특히, 배선밀도가 높은 MCM-D의 유전체 두께는 적어도 2 m 이내에서 제어되어야 한다. 500 MHz 주파수에서 MCM 배선의 전송감쇠는 문제가 되지 않으나 전송지연은 심각하여 배선과 부하와의 임피던스 정합이 필수적임을 알 수 있었다. MCM-D 배선은 인접배선이 오동작할 만큼 누하가 발생하지 않는데 비하여 MCM-L 배선은 심한 누하로 MCM 기판으로 사용이 불가능할 것으로 판단되었다. 마지막으로, 500 MHz의 고속 MCM 기판 설계에서는 전송선 거동에 대한 연구가 필요한 것을 알 수 있었다.

• ETRI Journal
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• 제36권2호
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• pp.286-292
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• 2014

This paper presents a compact structure composed of an upper high-impedance transmission line, a middle extended parallel coupled line, and a pair of inter-coupled symmetrical stepped impedance stubs. Detailed investigation into this structure based on an equivalent circuit analysis reveals that this proposed structure exhibits a quasi-elliptic low-pass filtering response with three transmission zeros. Moreover, the positions of the three transmission zeros can be tuned and reallocated flexibly by choosing the proper circuit parameters. Finally, the design concept is validated through the design, fabrication, and measurement of two exemplary low-pass filters (LPFs) with one single unit and two cascaded asymmetric units. The measured results agree well with the simulated results. In addition, in the range of $1.42f_c$ to $7.03f_c$, the fabricated quasi-elliptic LPFs experimentally demonstrate a very wide upper-stopband of 20 dB using a compact size of only $0.0089{\lambda}_g{^2}$, where ${\lambda}_g$ is the guided wavelength of a $50{\Omega}$ transmission line at the central frequency.