• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.1
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• pp.33-38
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• 1994

In this paper, waveguide banpass filters using H-plane step discontinuities are designed based on the field theory analysis and optimization of the resonator lengths as well as dimensions of discontinuities, instead of the conventional synthesis method based on the equivalent circuit. The waveguide inductive obstacles introduced by H-plane step discontinuities analyzed using mode-matching method and the generalized scattering parameters are derived. Using the derived scattering parameters of the discontinuities as well as those of resonators, waveguide bandpass filters are designed through optimization method, modified Razor search method proposed by J.H.Bandler. Using this design procedures, waveguide bandpass filters are designed and tested at X-band(center frequency 10GHz) as well as Ka-band(center frequency 35GHz).

• Publications of The Korean Astronomical Society
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• v.13 no.1 s.14
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• pp.123-128
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• 1998

The Blandford-Znajek process, which extracts the rotational energy of the supermassive black hole at the center of an active galactic nucleus, is now well explained and educated through the electronic circuit analysis established by Macdonald and Thorne. The Macdonald-Thorne circuits consist of the batteries and resistances of the central black hole and the astrophysical region around the accretion disk. In this letter we will consider the possibility whether we can connect coils and condensers in such circuits or not. If possible, that may explain a sudden corona-phenomenon in an active galactic nucleus. We conclude that a flash of order $\~5\times10^{40}\;ergs\;s^{-1}$ can occur around a $\~10^9M_\bigodot$ black hole through this process.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.11-15
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• 2002

In this paper, we have proposed the new configuration of wideband antenna using CPW fred lines. The proposed antenna has CPW feed lines and U-slot to achieve wade bandwidth with good impedance matching. The use of CPW feed line can decrease the number of substrates. It is compared with the conventional antenna find by a microstrip fled line. The parameters of CPW fred lines were studied by using the quasi-static approximation which is based on the conformal mapping method. The analysis of CPW discontinuities such as the tapered-step structure and the open ended gap were studied by using the quasi-static approximation which is based on the boundary element method. Also, the equivalent circuit model of multi-layer antenna were proposed using the cavity model. Experiment results of the proposed antenna 7how wide-bandwidth characteristics and good radiation patterns in passband.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.46-49
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• 2004

레이저 다이오드 (LD)의 광 직접 변조시 광자와 전자의 동역학에 의하여 입출력 관계가 결정된다. 이는 LD의 직접 변조 시 대역폭을 제한하는 요소로 작용한다. 높은 대역폭을 가지는 광송신기 설계를 위하여 LD의 등가회로 분석은 필수적이다. LD의 등가회로는 E/O response를 이용하여 소신호 분석을 통해 얻을 수 있으며, E/O response는 rate equation을 이용하여, 구할 수 있다. LD의 등가회로는 직렬 저항값, 기생 커패시턴스, 외부 회로와의 연결을 위한 와이어에 기인하는 인덕턴스 성분 등으로 구성된다. 본 논문에서는, rate equation을 사용하여 계산된 결과를 이용하여, LD의 등가회로를 도출하였다.

• Journal of Power Electronics
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• v.13 no.5
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• pp.854-860
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• 2013

The voltage variation problem at the point of common coupling (PCC) in a grid-connected wind turbine is investigated. The voltage variation problem is one of the most frequent power quality issues for the grid connection of large amounts of input power in a weak grid. Through the simplified modeling of the wind turbine and power network, the magnitude of PCC voltage variation is calculated by using the equivalent circuit parameters and output power of the wind turbine. The required amount of reactive power that can compensate the voltage variation is also presented analytically by using the vector diagram method. The proposed calculation and compensation method of the PCC voltage variation is verified by computer simulations and experiments.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.32-35
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• 2003

Nonlinear parameterization of OLED device from measurements of bias dependence of impedance spectra and parameter extraction using Levenberg-Marquardt complex nonlinear least square regression algorithm based on resistor-capacitor equivalent circuit model enables computer simulation of OLED power driving characteristics in forms of square-wave or sinusoidal output signal at arbitrary conditions. We introduce developed OLED power driving simulation software and discuss transient responses in voltage-or current-controlled operations as well as nonlinear characteristics of OLED, by presenting both the simulation and experimental results. This OLED simulation technique using impedance spectroscopy is extremely useful in predicting performance of the nonlinear device, especially in time-domain analysis of device operation.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.552-556
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• 1989

The line equations can be expressed by a set of nonhomogeneous differential equation where forcing terms of these equations have been adopted. Equivalent-circuit representations of this paper are derived from solutions of the equations. The contribution of the external wave to the line is expressed in terms of ideal sources in the form of a cascade connection to the line. These representations art conveniently applicable to the various types of transmission lines because these Lines can often be written in the form of a chain matrix.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.123-126
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• 2002

A proposed multi-layer ceramic (MLC) chip type band-pass filter (BPF) is presented. The MLC chip BPF has the benefits of low cost and small size. The BPF consists of coulped stripline resonators and coupling capacitors. The BPF is designed to have an attenuation pole at below the passband for a receiver band of IMT-2000 handset. The computer-aided design technology is applied for analysis of the BPF frequency characteristics. The passband and attenuation pole depend the coupling between resonators and coupling capacitance. The frequency characterics of the passband and attenuation pole are analysed with the variance of the coupling between resonators and coupling capacitance. An equivalent circuit and structure of MLC chip BPF are proposed. The frequency characteristics of the BPF is well acceptable for IMT-2000 application.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.27-34
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• 1995

The analysis of nonlinear equivalent circuit and the resonance characteristics of input current and output voltage were simulated, and their electrical properties are discussed in the transverse-type piezoelectric ceramic transformer. The nonlinear resonance characteristics of input current and output voltage showed by the thermal effect due to a higher driving current, the nonlinearity increased greatly as driving current increased. When load resistor was 100[M.ohm.], the nonlinear coefficient was -1.3. The nonlinear resonance curve of input current and output voltage for a variation of input voltage and load resistor agreed with the discussed theory. The output voltage increased nearly proportioned to input voltage when load resistors were below 50[M.ohm.], the voltage step-up ratio decreased when a load resistor was 100[M.ohm.] and their maximum value was 950.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.543-546
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• 2004

Bias and frequency-dependent impedance is a technique for the investigation of complex conductivity. At low frequency, complex impedance is dominated by resistive component, and at high frequency by capacitive component. We are going to present the results of the bias and frequency-dependent complex impedance in the device structure of $ITO/Alq_3/Al$ in the temperature range between 10K and 300k. And we will show to change radius of Cole-Cole plot. It will be decrease resistance by temperature. Also equivalent electrical circuit and dielectric relaxation can be accomplished by using the complex impedance analysis.