• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.724-727
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• 1999

The previous LQ-servo PI design methods have some serious design problems happened from the frequency matching of the maximum and minimum singular values of loop transfer function at both low and high frequency regions on the Bode plot. To solve these problems, this paper proposes a new design technique based on the inverse-optimal control and convex optimization.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.485-492
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• 1990

This paper propose a optimal design method for robust notion controllers of under-water vehicles using the combined technique between classical and modern theories. The proposed method is presented which utilizes classical control methods to obtain a good robustness and modern control methods to set optimal gains. LQ, SVD, multivariable frequency analysis and Bode-Root Locus (BRL) plot are used.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.356-360
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• 2003

At rotating machinery, Many factors had caused vibration. especially one of the major factor is mass unbalance. A sort of mass unbalance are followings; Static, Coupling, Single and Dynamic. In this paper, We had investigated abnormal vibration due to mass unbalance that changed phase whenever starting of steam Turbine at Combined Cycle.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.353-354
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• 2017

본 연구에서는 전압승압형 컨버터로 동작하는 부스트 컨버터의 최적 제어기법에 대해 서술한다. 부스트 컨버터를 상태평균화 모델을 이용하여 전달함수를 구한 다음, Root Locus와 Bode Plot을 이용하여 시스템 요구사항(Requirement)을 만족시키는 제어기 설계 방법을 제안한다.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.503-506
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• 2003

In this paper, we present the results of parameter estimation for do-dc converter model by system identification. The parameter estimation for dc-dc converter aims at the diagnosis of its operating status. we applied the system identification method for parameter estimation. For verification of estimated parameter, we compare bode plot of estimated system transfer function and measurement results of HP4194 instrument.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.139-140
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• 2016

본 논문은 위상천이 풀브리지 컨버터의 전압 제어기 설계에 있어 게인값의 선정에 따른 위상 이득, 게인 이득을 통해 안정도를 판별하고 게인값에 따른 시스템의 응답특성을 고려하여 최적값을 설계하는데 목표를 두고 있다. MATLAB의 Bode plot을 통해 안정도 및 응답특성을 확인하였고 PSIM 시뮬레이션을 통해 제어가 잘 되는지 확인하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.845-851
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• 1986

This Paper presents micro-computer simulation programs for a pneumatic control system. The simulation programs have been written in BASIC language which is suitable for 6502CPU with 48KB memory and consist of 11 programs which describe the time response and frequency response of the pneumatic actuation system. This simulation package is stored in 51/4 inch floppy diskette. The user requires no simulation expertise on the part of designer. As the result of using this simulation programs for the pneumatic control system with stabilizing tank, it has shown that the response time of the system using air as working medium takes more time to be settled but relatively stable rather than the system using helium.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.224-224
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• 2014

최근 기존의 아연 도금 강판의 성능을 향상시키기 위하여 다른 금속과의 합금 박막의 연구가 활발히 진행 중에 있다. 기존 아연 도금 강판에 비해 Mg를 함유한 Zn-Mg 합금 박막이 내식성이 우수하다고 알려져 있으며, 본 연구에서는 다양한 Mg 함량의 Zn-Mg 합금 타겟을 사용하여 Zn-Mg 박막을 합성하였다. 합성된 박막들의 내식성을 평가하기 위해서 Electrochemical Impedance Spectroscopy (EIS) 분석을 실시하였으며, 도출된 Nyquist plot 과 Bode phase angle plot 결과를 등가회로 피팅과 시뮬레이션을 실시하여 Mg 함량에 따른 Zn-Mg 박막의 내식성을 비교 분석하였다. Zn-Mg 박막은 Mg 함량이 증가할수록 내식성 또한 증가하였으며, 이는 Mg 함량에 따라 치밀해지는 미세구조에 의한 것으로 판단된다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.64-70
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• 2010

This paper presents how to decide on tuning factor(${\delta}$) and quality factor(Q) values in design of single-tuned passive harmonic filters. Tuning factor(${\delta}$) and quality factor(Q) values have to consider before decision on circuit parameters of passive filters. A Study on these two value has not been scarcely performed and only experienced values has been used in passive harmonic filter design by far. As a experienced value, in cases of 5th and 7th filter, tuning factor(${\delta}$) is about 0.94 and 0.96 respectively and quality factor(Q) is, in all cases of, 50. If Single-tuned passive harmonic filter will be off-tuned, performance of filter will be decreased steeply and occur to parallel resonance between system reactance and filter capacitance. Therefore During the operation, In order not to off-tuning, Filter must be tuned at former order than actual tuning order. This is the same that total impedance of filter must have a reactive impedance. In this paper, Tuning factor(${\delta}$) is decided via example of real system and using the bode-plot and then performance of filters confirmed by filter current absorbtion rate. And Quality factor(Q) decided using the bode plot in example system and then performance of filters confirmed by filter current absorbtion rate also, which makes a calculated filter parameters to satisfy IEEE-519 distortion limits. Finally, Performance of the designed passive harmonic filter using the tuning factor(${\delta}$) and quality factor(Q) values, decided in this paper is verified by experiment and shows that 5th, 7th, 9th, 11th and 13th current harmonic distortions are decreased within IEEE-519 distortion limits, respectively.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.46-53
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• 2013

Impedance spectroscopy is a non-destructive evaluation (NDE) method first proposed and developed for evaluating TGO layers with compressive stress inside thermally degraded plasma-sprayed thermal barrier coatings (PS TBCs). A bode plot (phase angle (h) vs. frequency (f)) was used to investigate the TGO layer on electrical responses. In our experimental study, the phase angle of Bode plots is sensitive for detecting TGO layers while applying compressive stress on thermal barrier coatings. It is difficult to detect TGO layers in samples isothermally aged for 100 hrs and 200 hrs without compressive stress, and substantial change of phase was observed these samples with compressive stress. Also, the frequency shift of the phase angle and change of the phase angle are observed in samples isothermally aged for more than 400 hrs.