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역히스테리시스 모델과 PID-신경회로망 제어기를 이용한 압전구동기의 정밀 위치제어
김정용,이병룡,양순용,안경관 제어·로봇·시스템학회 2003 제어·로봇·시스템학회 논문지 Vol.9 No.1
A piezoelectric actuator yields hysteresis effect due to its composed ferroelectric. Hysteresis nonlinearty is neglected when a piezoelectric actuator moves with short stroke. However when it moves with long stroke and high frequency, the hysteresis nonlinearty can not be neglected. The hysteresis nonlinearty of piezoelectric actuator degrades the control performance in precision position control. In this paper, in order to improve the control performance of piezoelectric actuator, an inverse modeling scheme is proposed to compensate the hysteresis nonlinearty. And feedforward - feedback controller is proposed to give a good tracking performance. The Feedforward controller is an inverse hysteresis model, base on neural network and the feedback control is implemented with PID control. To show the feasibility of the proposed controller and hysteresis modeling, some experiments have been carried out. It is concluded that the proposed control scheme gives good tracking performance.
이미지프로세싱기법을 이용한 포장이미지의 특성과 노이즈제거를 위한 알고리즘 선정
김정용,조윤호,Kim, Jung-Yong,Cho, Yoon-Ho 한국도로학회 2001 한국도로포장공학회 논문집 Vol.3 No.4
포장유지관리시스템에 있어서 포장표면 정보는 가장 중요한 인자 중의 하나이다. 따라서 일찍부터 선진국들은 자국의 현실에 알맞은 포장표면 조사장비와 프로그램을 개발하여 사용하고 있다. 국내의 경우 고가의 외국장비와 프로그램을 수입하여 사용하고 있으나 많은 문제점으로 인해 국산 장비와 포장표면 분석 프로그램 개발의 필요성이 대두되고 있다. 본 연구는 아스팔트 포장표면 분석 프로그램 개발을 위한 선행연구이다. 본 연구의 초점은 이미지프로세싱 기술을 이용한 포장표면 분석 원리를 규명하고 포장이미지의 특성 및 포장이미지의 노이즈를 효과적으로 제거하기 위한 알고리즘을 실험하는 것이다. ARAN(Automatic Road Analyser)의 균열맵을 분석 샘플로 이용하였으며, 포장이미지의 통계적인 특성, 히스토그램, FFT(Fast Fourier Transform)영상을 분석하여 일반적인 이미지에 비해 노이즈와 고주파 성분이 많고, 배경과 균열 분리가 어려운 특성을 규명하였다. 또한 노이즈 제거를 위해 다양한 필터를 적용하여 실험한 결과 마스크 크기가 3X3인 중간값 필터가 가장 효과가 좋은 것으로 나타났다. Pavement distresses are one of the most important data for pavement management systems. Inspection machines and its related programs have been used for operating tools in PMS developed in advanced countries. In Korea imported machines and programs for the length price ale utilized to get information of pavement condition from the field This study is launched for developing the program which can detect cracks on asphalt pavement due to many drawbacks in current PMS operation such as improper maintenance work and long resting period when it was broken. The focus of this study is to define principles to analyze pavement surface with digital image processing techniques, to test property of pavement images and to suggest an algorithm that reduces noises at test. To test images, the camera attached on the Automatic Road Analyser(ARAN) was used. Through the FFT images, histogram and statistical values of pavement images, it was found that the images had many noises with high-frequency components against general images, and it was difficult to subdivide pavement images into background or crack. Through several testing with various filters for noise reduction a 3X3 median filter was suggested to reduce noises effectively.
김정용 한국청소년복지학회 2004 청소년복지연구 Vol.6 No.2
About 10 years has passed since the youth voluntary service system was enforced in the Korean society. Nonetheless, the youth voluntary service has still failed to take firm hold in our society, though it is a fact that the system is required to be further complemented. The objective of this study is to identify the whole cause of failure of our youth voluntary service to take firm hold and further seek a method for our youth voluntary service to take deep root. We have discussed that in order to accomplish this objective, three analytic frameworks, i.e., behavioral framework, institutional framework and socio-structural framework are needed in terms of theoretical analysis. And, it has been discussed that each analysis through each analytic framework could take synergic effect in association with the other analyses through the other analytic frameworks. Not only the cause of failure of the youth voluntary service to take firm hold but also an alternative approach to eliminate the cause may be analytically examined in terms of three frameworks respectively, but ultimately, the analytic framework of this study resulted in the synergic effect of analysis through the three analytic frameworks. In this study, on the basis of the said analytic framework, the actual conditions and problems of our youth voluntary service have been investigated. It has been found out that such problems resulted from the limitations of the volunteer's thinking and attitude and the socio-structural limitations in addition to the institutional limitations. Also, it has been identified through examples in foreign countries that formation of the volunteer's thinking and attitude through the voluntary service education is a very important factor. However, it could not be found out even in examples in foreign countries how the socio-structural factor functions in the youth voluntary service. This was due to the limitations of this study. Nevertheless, we have suggested a tactical approach and a strategic approach enabling the youth voluntary service to take deep root on the basis of the theoretical analytic framework as derived theorectically and the results as somewhat verified empirically. The tactical approach was mainly focused on education related to formation of thinking and attitude of the youth, a behavior of the voluntary service, and in terms of the strategic approach, our suggestion was that it should be necessary to put continuous efforts for improvement and change of the socio-structure. However, this study involves some inherent limitations. Such limitations lie in the fact that the influential relation between the youth voluntary service and the socio-structural environment cannot be actually verified and we cannot be convinced of any socio-structural change. Therefore, this study cannot help being a part of open discussion.
김정용 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
ABS 형식 승인에 대한 규정, 적용범위, 절차, 효과에 대하여 발표하고, 정부 (Flag Authority, MED) 형식승인에 대한 관련 또는 대행 사항을 알아봄. 국내 시험 기관에 대한 본 선급의 인증 방침도 소개함.
김정용,D. C. Kim,K. Nakajima,H. Aoki,T. Mitsui 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.6
The near-field scanning optical microscope (NSOM) is a form of scanning probe microscope that achieves, through the use of the near-field, a spatial resolution significantly superior to that defined by the Abbe diffraction limit. Although the term spatial resolution has a clear meaning, it is often used in different ways in characterizing the NSOM instrument. In this paper, we describe the concept, the cautions, and the general guidelines of a method to measure the spatial resolution of an aperture-type NSOM instrument. As an example, a quantum dot embedded polymer film was prepared and imaged as a test sample, and the determination of the lateral resolution was demonstrated using the described method.