• 전력전자학회논문지
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• 제10권3호
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• pp.219-225
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• 2005

본 논문에서는 평균전류모드제어를 이용하는 컨버터의 전류응답을 예측할 수 있는 새로운 이산시간 소신호 모델을 구한다. 평균전류모드제어는 최대전류모드제어와 달리 전류제어를 위해 복잡한 보상기 회로를 사용하므로 컨버터의 동작 특성 해석이 어렵다. 평균전류모드제어를 사용하는 컨버터의 소신호 전류응답을 예측하기 위해 샘플러모델을 제안하고, 이 모델로부터 새로운 이산시간 소신호 모델을 구한다. 제안된 방식은 기존 방식과 달리 복잡한 형태의 보상기를 사용하는 컨버터에도 적용 가능하다. 제안한 새로운 이산시간 소신호 모델을 이용한 예측 결과를 스위칭 모델 시뮬레이션 프로그램인 PSIM을 이용한 시뮬레이션 결과 및 실험결과와 비교하여 제안한 새로운 이산시간 소신호 모델의 우수성을 보인다.

• 대한전자공학회논문지SD
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• 제49권4호
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• pp.1-6
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• 2012

본 논문에서는 고주파에서 동작하는 터널링 전계효과 트랜지스터 (TFET)의 소신호 파라미터 추출과 이에 대한 분석을 다루고 있다. 시뮬레이션으로 구현된 TFET의 채널 길이는 50 nm에서 100 nm 사이에서 변화되었다. Conventional planar MOSFET 기반의 quasi-static 모델을 이용하여 TFET의 파라미터 추출이 이루어졌으며 다른 채널 길이를 갖는 TFET에 대한 소신호 파라미터의 값을 게이트 바이어스 변화에 따라서 추출하였다. 추출 결과로부터 effective gate resistance와 transconductance, source-drain conductance, gate capacitance 등 주요 파라미터의 채널 길이 변화에 따른 경향성이 conventional MOSFET과 상당히 다른 것을 확인하였다. 그리고 $f_T$는 MOSFET과 달리 게이트 길이 역수의 값에 정확히 반비례하는 특성을 보였으며 TFET의 고주파 특성 향상을 transconductance의 개선이 아닌 gate capacitance의 감소에 의하여 가능함을 알 수 있었다.

• 한국철도학회논문집
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• 제4권3호
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• pp.79-86
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• 2001

The signal pattern recognition method by acoustic emission signal is applied to detect and classify the defects of a journal bearing in a power plant. AE signals of main defects such as overheating, wear and corrosion are obtained from a small scale model. To detect and classify the defects, AE signal pattern recognition program is developed. As the classification methods, the wavelet transformation analysis, the frequency domain analysis and time domain analysis are used. Among three analyses, the wavelet transformation analysis is most effective to detect and classify the defects of the journal bearing..

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.294-294
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• 2000

In this paper, we would like to discuss the signal processing and the algorithm for ECG analysis. The ECG gives us information about the condition of the heart muscle, because myocardial abnormality or infarction is inscribed on the ECG during myocardial depolarization and repolarization. Analyzing the ECG signal, we can find heart disease, for example, arrhythmia and myocardial infarction, etc. Particularly, detecting arrhythmia is more important, because serious arrhythmia can take away the life from patients within ten minutes. The wavelet transform decomposes the ECG signal into high and low frequency component using wavelet function. Recomposing high frequency bands including QRS complex, we can detect QRS complex and eliminate the noise from the original ECG signal. To recognize the ECG signal pattern, we adopted the curve-fitting partially and statistical method. The ECG signal is divided into small parts based on QRS complex, and then, each part is approximated to the polynomials. Comparing the approximated ECG pattern with some kinds of heart disease ECG pattern, we can detect and classify the kind of heart disease.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권4호
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• pp.377-387
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• 2012

An intrinsic small signal equivalent circuit model of Cylindrical/Surrounded gate MOSFET is proposed. Admittance parameters of the device are extracted from circuit analysis and intrinsic circuit elements are presented in terms of real and imaginary parts of the admittance parameters. S parameters are then evaluated and justified with the simulated data extracted from 3D device simulation.

• 전자공학회논문지D
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• 제35D권4호
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• pp.84-92
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• 1998

A program was developed to analyze the electrical characteristics and harmonic distrotion in a two-dimensional silicon BJT. The finite difference equations of the small signal and its second and thired harmonics for basic semiconductor equations are formulated treating the nonlinearity and time dependence with Volterra series and Taylor series. The soluations for three sets of simultaneous equations were obtained sequantially by a decoupled iteration method and each set was solved by a modified Stone's algorithm. Distortion magins and ac parameters such as input impedance and current gains are calculated with frequency and load resistance as parameters. The distortion margin vs. load resistancecurves show cancellation minima when the pahse of output voltage shifts. It is shown that the distortionof small signal characteristics can be reduced by reducing the base width, increasing the emitter stripe length and reducing the collector epitaxial layer doping concentration in the silicon BJT structure. The simulation program called TRADAP can be used for the design and optimization of transistors and circuits as well as for the calculation of small signal and distortion solutions.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.538-541
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• 2002

Dynamic analysis and compensation design for an asymmetrical half bridge do-dc converter are presented. A small-signal model is developed using the averaging method. Based on the proposed small-signal average model, the open loop transfer functions of the power stage were obtained and used for the compensation design. All theoretical predictions are validated by experiments on a prototype converter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.323-326
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• 2001

This paper describes the algorithm which can not only take account of voltage suability but also consider small signal stability. As for voltage stability both CPF and PoC methods are utilized to pinpoint the exact voltage collapse point. Then, using the converged load flow results full system matrix is configured and its eigenvalues are computed. The suggested algorithm is applied to the Two-area system, and verified its usefulness. In addition this paper also deals with the results of analyzing the two-area system in terms of voltage stability and small signal stability.

• 대한전기학회논문지:전력기술부문A
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• 제55권1호
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• pp.13-17
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• 2006

In this paper, the RCF(Resistive Companion Form) analysis method which is used to analyze small signal stability problems of non-continuous systems including switching devices. The RCF analysis method is mathematically rigorous and computes eigenvalue of the system periodic transition matrix based on discrete system analysis method. As an effect of switching operations, the eigenvalues of the systems are changed and newly unstable oscillation modes may be occurred. As an illustrating example, the oscillation modes of the system with different switching time intervals are computed exactly by the RCF analysis method and the results show that ON/OFF time intervals of switching equipments are important factors to make the system stable or unstable. This result shows that the RCF analysis method is very powerful to analyze small signal stability problems of power systems including switching devices such as FACTS equipments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2518-2521
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• 1999

A Full-bridge zero-voltage zero-current switching (ZVZCS) converter using transformer auxiliary winding is analyzed. A complete small-signal model for the control scheme is developed. The propoed model is accurate up to half the switching frequency. The dynamic characteristics are compared with those of the zero-voltage switching converter and buck converter. Model predictions are confirmed by experimental measurements.