• 제어로봇시스템학회논문지
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• 제10권2호
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• pp.112-124
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• 2004

A neural network based adaptive reconfigurable flight controller is presented for a class of discrete-time nonlinear flight systems in the presence of variations of aerodynamic coefficients and control effectiveness decrease caused by control surface damage. The proposed adaptive nonlinear controller is developed making use of the backstepping technique for the angle of attack, sideslip angle, and bank angle command following without two time separation assumption. Feedforward multilayer neural networks are implemented to guarantee reconfigurability for control surface damage as well as robustness to the aerodynamic uncertainties. The main feature of the proposed controller is that the adaptive controller is developed under the assumption that all of the nonlinear functions of the discrete-time flight system are not known accurately, whereas most previous works on flight system applications even in continuous time assume that only the nonlinear functions of fast dynamics are unknown. Neural networks learn through the recursive weight update rules that are derived from the discrete-time version of Lyapunov control theory. The boundness of the error states and neural networks weight estimation errors is also investigated by the discrete-time Lyapunov derivatives analysis. To show the effectiveness of the proposed control law, the approach is i]lustrated by applying to the nonlinear dynamic model of the high performance aircraft.

• 한국산업정보학회논문지
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• 제14권4호
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• pp.75-90
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• 2009

생산성 향상과 효율적인 프로세스 관리는 기존 업무의 문제점을 올바르게 파악하는 것에서부터 시작한다. 또한 데이터 수집에서 필요한 정보를 도출하는 데 많은 시간이 소요될 경우 고객의 요구와 수요를 충족시키고 업무의 효율성을 높이기 위한 지속적인 프로세스 관리가 더욱 어려워진다. 본 논문은 실시간 정보획득 기술의 도입을 통해 제조공정 관리상 발생 가능한 여러 문제점을 개선하기 위한 방안과 기초적 의사결정을 위한 상황인지(Context awareness) 시스템을 제시하는 것을 목적으로 한다. 공정 작업 중 획득한 데이터를 바탕으로 각 작업을 자동으로 분류하는 판단규칙을 제시하여 제조 현장에서의 상황인지를 구현하고자 하였다. 그리고 제안하는 개념과 구조를 작업자가 신속하게 문제를 파악하고 지시사항을 전달할 수 있는 사례를 기본적 시스템으로 구현하였다. 생산요소 객체 및 정보시스템의 데이터 일치와 공정에 대하 지속적이 모니터링을 통해 비효율적 자원 할당 및 공정 지연을 측정하고 해결하며 가시성을 높여 업무 효율을 지속적으로 향상시킬 수 있을 것이다.

• 한국인터넷방송통신학회논문지
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• 제10권3호
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• pp.145-152
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• 2010

최근 유비쿼터스 컴퓨팅 기술의 발전과 함께 센서 및 RFID에 관련한 정보 인식, 위치 측위와 같은 다양한 유비쿼터스 영역에 대한 관심과 연구가 증대되고 있다. 특히, 시공간 데이터를 다루는 실시간 위치 추적 서비스 기술이 대두되고 있다. 이에, ISO/IEC에서는 실시간 위치 추적 서비스의 데이타 호환성과 상호 운용성을 위해 RTLS 표준 명세를 제시하였다. 본 논문에서는 이동 객체의 시공간 데이타 스트림에 대한 효율적인 관리와 검색을 지원하는 시공간 질의 처리 시스템을 설계 및 구현하였다. 시공간 질의 처리 시스템의 시공간 미들웨어는 끊임없이 연속으로 들어오는 시공간 데이타 스트림을 실시간으로 처리하고 시공간 DBMS간의 양방향 동기화를 지원한다. 웹 서버는 서버와 클라이언트간의 상호 운용성을 위하여 SOAP(Simple Object Access Protocol) 메시지를 사용하며, 클라이언트의 SOAP 메시지를 분석하여 시공간 미들웨어의 CQL(Continuous Query Language)로 변환하는 기능을 지원한다. 마지막으로, 본 논문에서는 실시간 위치 추적 서비스에 적용해 봄으로써 시공간 질의 처리 시스템의 효용성을 입증하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.437-440
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• 1998

In this paper, the design method of fuzzy neural network(FNN) controller using indirect adaptive control technique is presented for controlling chaotic nonlinear systems. Firstly, the fuzzy model identified with a FNN in off-line process. Secondly, the trained fuzzy model tunes adaptively the control rules of the FNN controller in on-line process. In order to evaluate the proposed control method, Indirect adaptive control method is applied to the representative continuous-time chaotic nonlinear systems, that is, the Duffing system and the Lorenz system. Simulations are done to verify the effectivencess of controller.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 춘계학술대회 학술발표 논문집
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• pp.39-42
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• 1998

This paper proposes an adaptive fuzzy control scheme for a class of continuous-time nonlinear dynamic systems for which an explicit linear parameterization of the uncertainty is either unknown or impossible. In order to improve robustness under approximation errors and disturbances the proposed scheme includes deadzone in adaptation laws which varies its size adaptively. The assumption of known bounds on the approximation errors and disturbances is not required since those are estimated using adaptation laws. The overall adaptive scheme is proven to guarantee uniform ultimate boundedness in the Lyapunov sense.

• Journal of Power Electronics
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• 제14권3호
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• pp.432-443
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• 2014

In order to improve the output efficiency of solar cells and to extend the life span of batteries, the input currents of converters are required to be continuous. If low output voltage ripple is required at the same time, it is obvious that the application of basic two-order converters (such as Buck and Boost derived converters) will not be good enough. In this paper, a lot of non-isolated push-pull converters (NIPPCs) with continuous current will be introduced due to their lower current stress, higher efficiency and better EMC performance. By decomposing the converters into push-pull cells, inductor and free-wheeling diodes, two families of NIPPCs based on single inductor and coupled inductor separately are systematically generated. Furthermore, characteristics analyses for some of the generated converters are also shown in this paper. Finally, two prototypes based on the corresponding typical topologies are built in the lab to verify the theoretical outcomes.

• 한국경영과학회지
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• 제14권1호
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• pp.119-130
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• 1989

This paper presents average travel time models automated warehousing system where the stacker crane transports only one pallet at a time with the tchebychev travel, I/O point is located at the cornor of the rack, and items are stored by the class-based storage assignment rule. In this study, the racks are treated as the continuous rectangle in time and a statistical approach was used to develop the models. In order to test the proposed models, average travel times determined by the models are compared with the true values for various rack shapes.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.103-105
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• 1995

In this paper, though Simith controller is also used, we propose a new system configuration which can be regarded an SISO continuous nth-order plant with time delay of k-times of a sampling period as a linear discrete (n + k)th order plant of which all state variables can be available. Consequently, we can pply linear control system design techniques which do not consider the existence of time delay to the proposed system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.152-154
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• 2007

Anew discretization method for the input-driven nonlinear continuous-time system with time delay is proposed. It is based on the combination of Taylor series expansion and first-order hold assumption. The mathematical structure of the new discretization scheme is explored. The performance of the proposed discretization procedure is evaluated by case studies. The results demonstrate that the proposed discretization scheme can assure the system requirements even though under a large sampling period. A comparison between first order hold and zero-order hold is simulated also.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.593-596
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• 1997

This paper is concerned with the properties of zeros of discrete-time systems which are composed of a hold, a continuous-time plant and a sampler in cascade. Here the signal reconstruction is based on the fractional order hold. In order to overcome the implementing problem of the fractional order hold, the piecewise constant reconstruction method by use of the zero order hold is introduced. The properties of the zeros are explored in the limiting cases when the sampling period tends to zero. The stability conditions of the zeros for sufficiently small sampling periods are also presented.