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이동기(DongGi Lee),이우상(Woo-sang Lee) 한국정보기술학회 2008 한국정보기술학회논문지 Vol.6 No.6
When mathematical models are used to describe real systems, the differences between the mathematical models and the real systems can cause poor performance of control systems. Therefore, when controllers are used to reduce the random vibration because of external excitation, we cannot expect that control systems achieve satisfactory control result. Hence, it is important that robust feedback stabilization of uncertain systems has been one of main topics in control applications. In this paper, design and anlysis of unified robust feedback control system are presented using the state-space approach. Using this approach, we concentrate on the analysis of control system stability with parameter uncertainty. The result of numerical simulation shows that the designed controller can be applied very well to the problem of degradation of control system performance.
이재득(Jaedeuk Lee),천성관(Sunggwan Cheon),이동기(Donggi Lee),최해창(Haechang Choi),이기욱(Kiwook Lee) 한국해양환경·에너지학회 2021 한국해양환경공학회 학술대회논문집 Vol.2021 No.10
본 연구에서는 1MW급 조류발전기에 적용될 제어시스템과 전력변환장치에 대한 설계와 분석을 수행하였다. 1MW급 조류발전시스템이 울돌목 해역의 조류발전 실해역 시험장에 설치되는 조건으로 저압형 AC 690V 전력변환장치를 설계하였으며 현재 제작 중에 있다. 제어시스템은 직접구동형 영구자석형 발전기, 피치시스템, 나셀시스템, HVAC, 빌지(bilge) 등으로 구성된 시스템의 제어요소와 이들에 대한 제어방법에 대하여 분석하였다. In this study, we was studied on the control and power conversion system(PCS). It is applied to the 1MW tidal power generation system. A AC 690V PCS is being designed and manufactured as a condition that a tidal current generator be installed at sea test bed for tidal current power in the Uldolmok sea area. The control system analyzed the control elements and control methods of the system consisting of direct driving PMSG(Permanent Magnet Synchronous Generator), pitch systems, nacelle systems, HVACs, bilge, etc.
크라우드 소싱 기반 딥러닝 선호 학습을 위한 쌍체 비교 셋 생성
유기현,이동기,이창우,남광우,Yoo, Kihyun,Lee, Donggi,Lee, Chang Woo,Nam, Kwang Woo 한국산업정보학회 2022 한국산업정보학회논문지 Vol.27 No.5
With the development of deep learning technology, various research and development are underway to estimate preference rankings through learning, and it is used in various fields such as web search, gene classification, recommendation system, and image search. Approximation algorithms are used to estimate deep learning-based preference ranking, which builds more than k comparison sets on all comparison targets to ensure proper accuracy, and how to build comparison sets affects learning. In this paper, we propose a k-disjoint comparison set generation algorithm and a k-chain comparison set generation algorithm, a novel algorithm for generating paired comparison sets for crowd-sourcing-based deep learning affinity measurements. In particular, the experiment confirmed that the k-chaining algorithm, like the conventional circular generation algorithm, also has a random nature that can support stable preference evaluation while ensuring connectivity between data.
단일 제어 리야프노프 알고리즘에 의한 스마트 감쇠 시스템의 설계
허광희 ( Heo Gwanghee ),이규 ( Lee Giu ),이동기 ( Lee Donggi ),이우상 ( Lee Woosang ) 한국구조물진단유지관리공학회 2004 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.8 No.1
The aim of this paper is to present the results of the research to design a smart damping system using the MR-damper which would contribute to reducing the vibration of a structure with external excitation. A reduced model of three-storied structure was built and controled by two MR dampers which were placed one between the ground and the first floor, and the other between the first and second floors. The state-space model for the design of a controller is defined by structural modal matrices improved by modal matrix method. The modal matrices are obtained by using the results of dynamic experimental testing and numerical analysis. The control algorithm acquired by the MR-damper is applied to a numerical model which adopts the Lyapunov stability theory transformed into a unified control system. With analyzing the result of vibration control of unified system and applying unified Lyapunov stability theory, the efficiency of smart damping system is demonstrated.
코로나 19가 고령층의 온라인 사회 참여와 온라인 네트워크 활동에 미치는 영향 - 디지털 정보격차를 중심으로 -
홍성효 ( Hong¸ Seonghyo ),이동기 ( Lee¸ Donggi ) 한국자치행정학회 2021 한국자치행정학보 Vol.35 No.3
본 논문은 고령층을 대상으로 이들의 사회적 참여가 코로나19로 인해 어떻게 변화하였는지를 분석한다. 고령층은 일반 국민과 비교하여 디지털 정보격차로 인해 온라인을 통한 활동이 제한적일 뿐만 아니라 코로나19로 인해 대면 활동에서도 제약을 지니기 때문에 이들의 사회적 참여 및 네트워크 활동에 대한 코로나19의 부정적 영향이 상대적으로 클 것이다. 본 논문은 고령층의 일반 국민 대비 온라인을 통한 사회적 참여 및 네트워크 활동의 코로나19 전후 변화를 이중차분 분석틀을 적용해 실증적으로 분석한다. 회귀분석 결과에 의하면, 코로나19를 전후로 일반 국민 대비 고령층의 온라인을 통한 사회적 참여는 상대적으로 감소하였으며 이는 이들의 사회적 참여 제한이 상대적으로 커졌음을 의미한다. 고령자의 증가와 이들의 정신적 건강 문제는 우리 사회가 해결해야 하는 과제들 가운데 하나에 해당하였다. 하지만, 본 논문의 실증분석결과는 코로나19로 인해 독거 노령자의 사회적 참여가 보다 더 제약을 받게 되었기 때문에 이들에 대한 사회적 관심과 보살핌을 강화하는 정책이 필요하다. This paper analyzes how the social participation of the elderly has changed due to COVID-19. In particular, compared to the general public, not only have their online activities limited due to the digital information gap, but also face-to-face activities due to COVID-19, so the negative impact of COVID-19 on their social participation and network activities is relatively large. will be. This paper empirically analyzes the changes in social participation and network activities online and before and after COVID-19 of the elderly compared to the general population by applying a double-difference analysis framework. According to the results of the regression analysis, the social participation of the elderly through online was relatively decreased compared to the general public before and after Corona 19, which means that their social participation restrictions were relatively large. The increase of the elderly and their mental health problems have been one of the challenges that our society has to solve. However, the empirical analysis results of this paper show that social participation of the elderly living alone is more restricted due to COVID-19, so a policy to strengthen social interest and care for them is needed.