• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.168-171
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• 1999

A fault-tolerant system should have a high availability and high reliability to maintain a given system stable against sudden faults in the system. In this paper, we propose a new types of fault tolerant system based on a fault detection bus. The fault detection bus is designed and implemented to detect any errors by comparing event-output signals from two processor modules. It employs the hot standby sparing fault detection method〔1〕 to provide continuity of services even if a system fault occurs. The prototype fault tolerant system is currently being implemented on a management system with two processor modules.

• 품질경영학회지
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• 제39권2호
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• pp.234-243
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• 2011

Multivariate control charts are widely used to monitor the performance of a multivariate process over time to maintain control of the process. Although existing multivariate control charts provide control limits to monitor the process and detect any extraordinary events, it is a challenge to identify the causes of an out-of-control alarm when the number of process variables is large. Several fault identification methods have been developed to address this issue. However, these methods require a normality assumption of the process data. In the present study, we propose a bootstrapped-based $T^2$ decomposition technique that does not require any distributional assumption. A simulation study was conducted to examine the properties of the proposed fault identification method under various scenarios and compare it with the existing parametric $T^2$ decomposition method. The simulation results showed that the proposed method produced better results than the existing one, especially in nonnormal situations.

• 디지털산업정보학회논문지
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• 제11권4호
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• pp.13-24
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• 2015

Customer complaints handling helps organizations to retain existing customers and attract new customers, as well. As Voice of the Customer (VOC) is one of the main sources of customer complaints, many organizations utilize VOC to enhance customer satisfaction. Effective management of VOC has been proved as one of the best ways to maintain organization's brand image and reputation. In spite of its importance, little has been reported on the utilization of VOC to detect faults in a telecommunication industry. In this paper, association rule mining based on VOC is used to identify root fault causes of a telecommunications network. To do that, VOC of a Communication Service Provider has been collected first. Then, association rule mining has also been conducted with various support and confidence levels. As a result, root fault causes of the telecommunications network can be identified. It is expected that this study can be used as a basis for decisions about customer satisfaction management such as preventive maintenances or reduction of the customer maintenance cost.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제10권1호
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• pp.83-93
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• 2006

본 논문에서는 유비쿼터스 컴퓨팅 환경에서 규칙 기반의 네트워크 장애 복구 시스템을 제안한다. 이 시스템은 유비쿼터스 컴퓨팅 환경에서 네트워크에 장애가 발생하였을 때, 정해진 규칙을 기반으로 장애를 스스로 복구할 수 있는 장애 관리 시스템이다. 시스템에 적용되는 규칙들을 네트워크 장애의 원인으로 분류하여 제시하였다. 그리고 본 논문에서는 네트워크 장애 복구 시스템이 각 상황에 맞게 규칙이 적용됨을 시뮬레이션을 통해 증명하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 추계학술대회 논문집
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• pp.280-287
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• 1998

In this paper, Dynamic Fault Tree algorithm(DFT algorithm) is presented. This new algorithm provides a concise representation of dynamic fault tolerance system structure with redundancy, dynamic redundancy management and complex fault ＆ error recovery techniques. And it allows the modeler to define a dynamic fault tree model with the relative advantages of both fault tree and Markov models that captures the system structure and dynamic behavior. This algorithm applies to TMR and Dual-Duplex systems with the dynamic behavior and show that this algorithm captured the dynamic behavior in these systems with fault ＆ error recovery technique, sequence-dependent failures and the use dynamic spare. The DFT algorithm for solving the problems of the systems is more effective than the Markov and Fault tree analysis model.

• 산업공학
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• 제25권2호
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• pp.170-177
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• 2012

Process control is essential to operate the semiconductor process efficiently. This paper consider fault classification of semiconductor based cyclic signal for process control. In general, process signal usually take the different pattern depending on some different cause of fault. If faults can be classified by cause of faults, it could improve the process control through a definite and rapid diagnosis. One of the most important thing is a finding definite diagnosis in fault classification, even-though it is classified several times. This paper proposes the method that one-class classifier classify fault causes as each classes. Hotelling T2 chart, kNNDD(k-Nearest Neighbor Data Description), Distance based Novelty Detection are used to perform the one-class classifier. PCA(Principal Component Analysis) is also used to reduce the data dimension because the length of process signal is too long generally. In experiment, it generates the data based real signal patterns from semiconductor process. The objective of this experiment is to compare between the proposed method and SVM(Support Vector Machine). Most of the experiments' results show that proposed method using Distance based Novelty Detection has a good performance in classification and diagnosis problems.

• 산업경영시스템학회지
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• 제47권2호
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• pp.10-20
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• 2024

In recent automated manufacturing systems, compressed air-based pneumatic cylinders have been widely used for basic perpetration including picking up and moving a target object. They are relatively categorized as small machines, but many linear or rotary cylinders play an important role in discrete manufacturing systems. Therefore, sudden operation stop or interruption due to a fault occurrence in pneumatic cylinders leads to a decrease in repair costs and production and even threatens the safety of workers. In this regard, this study proposed a fault detection technique by developing a time-variant deep learning model from multivariate sensor data analysis for estimating a current health state as four levels. In addition, it aims to establish a real-time fault detection system that allows workers to immediately identify and manage the cylinder's status in either an actual shop floor or a remote management situation. To validate and verify the performance of the proposed system, we collected multivariate sensor signals from a rotary cylinder and it was successful in detecting the health state of the pneumatic cylinder with four severity levels. Furthermore, the optimal sensor location and signal type were analyzed through statistical inferences.

• 컴퓨터교육학회논문지
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• 제11권3호
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• pp.81-89
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• 2008

광범위 분산 컴퓨팅 시스템인 그리드 컴퓨팅에서는 자원 결함의 발생 정도가 기존의 병렬 컴퓨팅보다 더 높다. 그리드 컴퓨팅에서 자원들의 결함은 작업 수행에 있어서 치명적인 영향을 줄 수 있기 때문에 결함 포용 기능은 필수적인 요소이다. 그리고 그리드 서비스들은 바람직한 작업의 수행을 위해 그리드 자원들의 최소한의 서비스 품질을 요구한다. 하지만 그리드 컴퓨팅 서비스를 제공하는 대표적인 미들웨어인 글로버스(Globus)는 결함 탐지 서비스와 관리 서비스 그리고 QoS 요구사항을 만족하는 결함 포용 서비스를 제공하지 않는다. 이에 본 논문에서는 그리드 컴퓨팅에서 QoS 요구사항을 만족하는 결합 포용 서비스를 제안한다. 이를 위해 본 논문에서는 프로세스 결함, 프로세서 결함, 네트워크 결함과 같이 결함의 정의를 확장한다. 그리고 자원 스케줄링 서비스, 결함 탐지 서비스, 결함 관리 서비스를 제안하고 구현 및 실험 결과를 제시한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.149-151
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• 2011

This paper describe that restoration ability raising method of power system operator when Power System fault happen. This paper introduce score management method about simulation training when supposed fault happened and essencial fault have to be trained for power system operator.

• Journal of Mechanical Science and Technology
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• 제18권11호
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• pp.1961-1968
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• 2004

The design of a reliable and failsafe control system requires that sensor failures be detected and identified within acceptable time limit so that system malfunction can be prevented. This paper presents a model-based approach to sensor fault detection with applications to vehicle stability control systems. The effectiveness of the proposed method is illustrated through test data-based evaluation. Vehicle test data-based evaluation results show that the proposed fault management scheme can be used for the design of a failsafe VSCs.