• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.358-361
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• 1996

In this paper, we discuss decentralized optimal fault tolerant supervisory control issues on the basis of failure analysis and diagnosis from the angle of discrete event dynamic system. We address the detectability and the observability problems, and develope fault tolerant supervisory control system upon the failure analysis and diagnosis schemes. A complete min-cut is introduced and the procedure for finding the achievable or nonachievable layered optimal legal sublanguages is suggested for a preferential option among the reachable states in the controlled plant. A layered optimal supervisory control framework is proposed upon these. We extend the concept of decentralized supervisory control by considering the problem of combination of decentralized with centralized control in case pure decentralized control happens to be inadequate. We introduce the concept of locally controllable pair and present a hybrid decentralized supervisory control framework. Finally, we propose the analytical framework for a decentralized optimal fault tolerant supervisory control systems.

• 제어로봇시스템학회논문지
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• 제4권2호
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• pp.264-272
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• 1998

This paper proposes a fault detection and recovery mechanism for a fault-tolerant Mini-MAP system, and provides detailed techniques for its implementation. This paper considers the fault-tolerant Mini-MAP system which has dual layer structure from the LLC sublayer down to the physical layer to cope with the faults of those layers. For a good fault detection, a redundant and hierarchical fault supervision architecture is proposed and its implementation technique for a stable detection operation is provided. Information for the fault location is provided from data reported with a fault detection and obtained by an additional network diagnosis. The faults are recovered by the stand-by sparing method applied for a dual network composed of two equivalent networks. A network switch mechanism is proposed to achieve a reliable and stable network function. A fault-tolerant Mini-MAP system is implemented by applying the proposed fault detection and recovery mechanism.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
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• pp.231-234
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• 2003

This paper designs and implements fault-tolerant server of meta server for shared filesystem (SANfs) in SAN environment. SANfs is the filesystem that many clients can share data in Network-attached storage in SAN environment and meta server is the server that processes file operation in SANfs. The focus of this paper is the implementation of fault-tolerant server of meta server in SANfs. In the event of a meta server, meta server failovers to a fault-tolerant server where its processing continues seamlessly. If meta server doesn't restore, fault-tolerant server searches reliable client and makes another fault-tolerant server and work as meta server. Heartbeat monitors meta server and shadow server and controls them.

• 자동차안전학회지
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• 제15권2호
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• pp.13-20
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• 2023

This paper presents a fault tolerant control strategy for Steer-by-Wire (SbW) systems. Among many problems to be solved before commercialization of SbW systems, maintaining reliability and fault tolerance in such systems are the most pressing issues. In most previous studies, dual steering motors are used to achieve actuation redundancy. However, relatively few studies have been conducted to introduce fault tolerant control strategies using rear wheel steering system. In this work, an actuator fault in front wheel steering is compensated by active rear wheel steering. The proposed fault tolerant control algorithm consists of disturbance observer and sliding mode control. The fault tolerant control performance of the proposed approach is validated via computer simulation studies with Carsim vehicle dynamics software and MATLAB/Simulink.

• 인터넷정보학회논문지
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• 제6권6호
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• pp.23-34
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• 2005

대규모 병렬 연산에 있어서, 계산 노드 혹은 통신 네트워크의 장애는 연산 실패로 끝나 계산자원이 낭비된다. 이를 해결하는 무정지형 MPI 라이브러리들이 제안되어 있으나 이들은 MPI 표준을 따르지 않아 이식성의 문제가 있다. 본 논문에서는 응용 프로그램의 수준에서 비동기 연산과 표준 MPI 함수만 사용하여 이식성의 문제를 해결하고 장애 복구 메커니즘을 단순화하며 수렴속도를 높이는 무정지형 선형 시스템의 해법을 제안한다.

• 전력전자학회논문지
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• 제18권3호
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• pp.205-210
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• 2013

This paper presents a novel hall sensor fault detection and fault-tolerant control method for a high-speed permanent magnet synchronous motor (PMSM) drive system. A phase locked loop (PLL) type position estimator is used with a conventional interpolation based rotor position estimator to reduce position errors due to misalignment of hall sensors. The expected trigger time of hall sensor's output is used for detecting hall sensor fault condition and the PLL type position estimator is reconfigured for fault-tolerant control at the hall sensor fault condition. The proposed method can minimize current ripples during the transition from sensored control using hall sensors to sensorless control. Experimental results have been proposed to prove the validity of the proposed method.

• Journal of Power Electronics
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• 제12권1호
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• pp.24-32
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• 2012

Direct duty-ratio PWM schemes for continuous fault tolerant operation of matrix converter-fed motor drives are presented. The proposed method features simple modular modulation structure based on per output phase concept, which requires no additional modification on the normal modulation schemes for fault-tolerant applications. Realizations of fault-tolerant strategy applied to different system configurations are also treated to enhance the system flexibility. The proposed method can be effectively applied to treat the motor open phase fault and converter switching device failure. Simulation and experimental results show the feasibility and validation of the proposed strategies.

• 한국정보통신학회논문지
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• 제14권7호
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• pp.1634-1640
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• 2010

본 논문에서는 자동화설비에서 가장 많이 사용되는 근접센서와 실린더를 기준으로 두 가지 모델을 적용하여 "고장허용 시스템 구축"에 관한 연구를 진행하였다. Free Flow 컨베이어 상에서 센서의 고장발생 시 가상센서모드 (Virtual Sensor Mode)로 전환되어 정상동작 하는 것을 시뮬레이션을 통해 구현을 하였으며, 실린더의 내압(압력강하)을 이용하여 실린더의 동작 시 부하에 따른 아날로그 데이터변화를 확인함으로써 고장허용 시스템을 다양하게 적용할 수 있는 토대를 마련하였다. 이러한 방법은 실린더의 수명예상은 물론 Grease 주입예상시기와 실린더의 불량유무판단 등 개발자의 능력에 따라 여러 가지 응용이 가능할 것이라 생각된다.

• 전력전자학회논문지
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• 제5권4호
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• pp.409-416
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• 2000

시스템 특성상 fault tolerant system을 위해 두개의 컨버티를 1개의 전류센서를 사용하여 영상변류기 동적 방식으토 병렬 운전하는 경우 컨버터에 고자이 발생하면 영상변류기 출력은 두 컨버터 공급 전류 차이이므로, 어떤 컨버터에서 고장이 발생하였는지 고정 탐지 및 분리가 곤란히였다. 본 논문에사는 fault tolerant system를 위해 2 개의 컨버터를 병렬 운전하는 경우 캔버터의 고장 탐지 및 분리를 위한 방안올 제시하고 실험을 통하여 제안한 방법의 타당성을 확인하였다.

• 대한기계학회논문집A
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• 제21권3호
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• pp.470-476
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• 1997

The dynamic characteristics of industrial processes frequently cause an abnormal situation which is undesirable in terms of the productivity and the safety of workers. The goal of fault-tolerance is to continue performing certain activities even after the failure of some system cononents. A fault-tolerant intelligent monitoring and control system which is robust under disturbances is proposed in this paper. Specifically, the fault-tolerant monitoring scheme proposed consists of two process models and the inference module to preserve such a robustness. The results of turning experiments demonstrate the effectiveness of the fault-tolerant scheme in the presence of built-up edge.