• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.974-977
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• 2003

The GPS/INS integration system navigation can provide improved navigation performance and has been widely used as a main navigation system for military and commercial vehicles. When two navigation systems are tightly coupled and the structure is complicated, a fault in either the GPS or the INS can lead to a disastrous failure of the whole integration system. This paper proposes a real-time fault detection method for an AGPS/INS integration system. The proposed fault detection method comprises a BIT and a fault detection algorithm based on chi-square test. It is implemented by real-time software modules to apply the AGPS/INS integration system and van test is carried out to evaluate its performance.

• 대한기계학회논문집
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• 제18권11호
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• pp.2846-2859
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• 1994

This work deals with kinematic analysis of fault-tolerant 3 degree-of-freedom spherical modules which have force redundancies in its parallel structure. The performance of a redundantly actuated four-legged module with no actuator failure, a single actuator failure, partial and half failure of dual actuator are compared to that of a three-legged module, in terms of maximum force transmission ratio, isotropic characteristics, and fault-tolerant capability. Additionally, a system with an excess number of small floating actuators is considered, and the contribution of these small actuators to the force transmission and fault-tolerant capability is evaluated. This study illustrates that the redundant actuation mode allows significant saving of input actuation effort, and also delivers a fault tolerance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.449-451
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• 2000

Arcing fault on overhead lines can be detected by amplitude of the arc voltage using numerical algorithm. In the case of transient fault, the arc voltage has any high value. In the case of permanent fault, the arc voltage is near zero. Thus, fault distance estimation should be performed by digital distance relay algorithm[3]. The purpose of this study is to build a structure for modeling of arcing fault detection and fault distance estimation algorithm using Matlab programming. Additionally, this algorithm has been designed in Graphical User Interface(GHI). So, this method using GUI interface of Matlab can reduce the number of simulation steps in modeling the distance relay.

• 한국정밀공학회지
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• 제15권2호
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• pp.35-44
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• 1998

This paper describes multiple fault diagnosis method in complex system with hierarchical structure. Complex system is divided into subsystem, item and component. For diagnosing this hierarchical complex system, it is necessary to implement special neural network. We introduced Modular Artificial Neural Network(MANN) for this purpose. MANN consists of four level neural network, first level for symptom classification, second level for item fault diagnosis, third level for component symptom classification, forth level for component fault diagnosis. Each network is multi layer perceptron with 7 inputs, 30 hidden node and 7 outputs trained by backpropagation. UNIX IPC(Inter Process Communication) is used for implementing MANN with multitasking and message transfer between processes in SUN workstation. We tested MANN in reactor system.

• Transactions on Control, Automation and Systems Engineering
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• 제1권1호
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• pp.54-61
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• 1999

FCM(Fuzzy Cognitive Map) is proposed for representing causal reasoning. Its structure allows systematic causal reasoning through a forward inference. By using the FCM, authors have proposed FCM-based fault diagnostic algorithm. However, it can offer multiple interpretations for a single fault. In process engineering, as experience accumulated, some form of quantitative process knowledge is available. If this information can be integrated into the FCM-based fault diagnosis, the diagnostic resolution can be further improved. The purpose of this paper is to propose an enhanced FCM-based fault diagnostic scheme. Firstly, the membership function of fuzzy set theory is used to integrate quantitative knowledge into the FCM-based diagnostic scheme. Secondly, modified TAM recall procedure is proposed. Considering that the integration of quantitative knowledge into FCM-based diagnosis requires a great deal of engineering efforts, thirdly, an automated procedure for fusing the quantitative knowledge into FCM-based diagnosis is proposed by utilizing self-learning feature of neural network. Finally, the proposed diagnostic scheme has been tested by simulation on the two-tank system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.197-201
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• 1988

A reliable Analytical Redundancy(AR) based Fault Detection Scheme(FDS) that can detect, discriminate sensor fault and process fault is presented. And a Fault Tolerant Control System ( FTCS ) with the FDS that performs original control objective without considerable loss of control performance in the face of sensor/process faults is constructed. These propositions are valuable in the sense that it resolves the well known sensitivity problem and that sensor/process faults can be detected, discriminated so that effects of any fault can be promptly accomodated by reconfiguring control system structure automatically.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
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• pp.321-328
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• 1998

A controller and sensor fault tolerant system jot a steam generator is designed with fuzzy logic. A structure of the : proposed fault tolerant redundant system is composed of a supervisor and two fuzzy weighting modulators. A supervisor alternatively checks a controlled and a sensor induced performances to identify Which Part, a controller or a sensor, is faulty. In order to analyze controller induced performance both an error and a charge in error of the system output an chosen as fuzzy variables. The fuzzy logic jot a sensor induced performance uses two variables : a deviation between two sensor outputs and its frequency, Fuzzy weighting modulator generates an output signal compensated for faulty input signal. Simulations show that the : proposed fault tolerant control scheme jot a steam generator regulates welt water level by suppressing fault effect of either controllers or sensors. Therefore through duplicating sensors and controllers with the proposed fault tolerant scheme, both a reliability of a steam generator control and sensor system and that of a power plant increase even mote.

• Journal of Electrical Engineering and Technology
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• 제6권4호
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• pp.474-483
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• 2011

Solid-state fault current limiters (SSFCL) in power systems are alternative devices to limit prospective short circuit currents from reaching lower levels. Fault current limiters (FCL) can be classified into two categories: R-type (resistive) FCLs and L-type (inductive) FCLs. L-type FCL uses an inductor to limit fault level and is more efficient in suppressing voltage drop during a fault. In contrast, R-type FCL is constructed with a resistance and is more effective in consuming the acceleration energy of generators during a fault. Both functions enhance the transient stability of the power system. In the present paper, a novel SSFCL is proposed to enhance power system transient stability and power quality. The proposed SSFCL uses both functions of an L-type and R-type FCL. SSFCL consists of four diodes, one self-turn-off IGCT, a current-limiting by-pass inductor (L), and a variable resistance parallel with an inductor for improvement of power system stability and prevention of over-voltage across SSFCL. The main advantages of the proposed SSFCL are the simplicity of its structure and control, low steady-state impedance, fast response, and the existence of R-type and Ltype impedances during the fault, all of which improve power system stability and power quality. Simulations are accomplished in PSCAD/EMTDC.

• 한국전자통신학회논문지
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• 제3권4호
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• pp.276-281
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• 2008

배전계통은 여러 가지 이유로 잦은 고장을 경험하기 때문에 고장위치 추정은 전력공급 신뢰도 측면에서 매우 중요하다. 그렇지만 배전계통은 주 선로에서 분기되는 3상 및 단상 분기선을 가지는 수지상 구조로 설계되며 각 구간 상에 수개의 로드 탭을 가지기 때문에 고장점 표정이 어렵다. 따라서 본 연구에서는 기존의 전력계통 고장점 표정기법에 대해서 조사, 분석하여 배전자동화시스템의 중앙제어장치에서 효과적으로 실행할 수 있는 고장거리 계산 기법을 결정한다. 그리고 EMTP 모의 결과를 통해 결정된 방법의 유효성을 검증한다.

• Smart Structures and Systems
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• 제17권6호
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• pp.1031-1053
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• 2016

The health conditions of in-service civil infrastructures can be evaluated by employing structural health monitoring technology. A reliable health evaluation result depends heavily on the quality of the data collected from the structural monitoring sensor network. Hence, the problem of sensor fault diagnosis has gained considerable attention in recent years. In this paper, an innovative sensor fault diagnosis method that focuses on fault detection and isolation stages has been proposed. The dynamic or auto-regressive characteristic is firstly utilized to build a multivariable statistical model that measures the correlations of the currently collected structural responses and the future possible ones in combination with the canonical correlation analysis. Two different fault detection statistics are then defined based on the above multivariable statistical model for deciding whether a fault or failure occurred in the sensor network. After that, two corresponding fault isolation indices are deduced through the contribution analysis methodology to identify the faulty sensor. Case studies, using a benchmark structure developed for bridge health monitoring, are considered in the research and demonstrate the superiority of the new proposed sensor fault diagnosis method over the traditional principal component analysis-based and the dynamic principal component analysis-based methods.