• 한국인터넷방송통신학회논문지
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• 제11권2호
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• pp.135-143
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• 2011

현재의 망관리시스템들은 네트워크 장치에서 제공하는 경보의 심각도 정도로만 유효한 정보를 제공해 주며, 장애분석 과정이 주로 기술적인 숙련도가 높은 전문 운용 인력에 의존적이다. 이러한 이유 때문에 발생한 경보에 대하여 실제 장애 여부를 판단하는데 상당한 시간이 소요되며, 비교적 높은 인력 투입비용이 소요되고 있다. 따라서 이러한 문제를 해결하기 위해 본 연구에서는 네트워크 시설의 과거 경보발생 이력 및 장애처리 이력을 기반으로 각 경보에 대한 장애 가능성을 확률적으로 분석하고, 장애에 대한 적합한 조치 방법을 신뢰수준과 함께 안내하는 방법과 이를 실제 자동화된 시스템으로 구현하기 위해 필요한 프로그램 설계를 제시한다. 또한 사례연구를 통하여 제안된 방법이 실제 어떻게 사용될 수 있는지를 보여준다.

• 정보처리학회논문지A
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• 제15A권3호
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• pp.151-154
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• 2008

서비스 이동과 자원 상태 변화 등 실행 환경 변화가 빈번히 발생하는 그리드 컴퓨팅 환경은 다양한 응용 프로그램 작업 환경을 지원하고 사용자에게 끊임없는 작업 환경을 보장하기 위하여 고가용성을 지원하는 미들웨어가 필수적으로 필요하다. 기존의 분산 환경 미들웨어 역시 고가용성 지원 서비스가 일부 연구자에 의해 진행되고 있으나 공개표준은 아니며 다양한 그리드 서비스에 대한 고려가 없다. 본 논문에서는 환경에 따라 적응하는 서비스 미들웨어 런타임 서비스 관리 시스템을 통해 자율적으로 작업 환경을 재구성하도록 하여 미들웨어의 가용성을 증대시키고 안정적으로 서비스의 계속성과 데이터 및 자료의 일관성을 보장하는 방법을 제시하고 프로토타입 Wapee(Web-Service based Application Execution Environment)를 통해 실제 환경에서 적용 가능성을 확인한다.

• 한국멀티미디어학회논문지
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• 제20권12호
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• pp.1970-1979
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• 2017

Computerization of educational administration following educational informatization of government has been steadily improved for the purpose of teachers' offload and job efficiency, finally resulting that NEIS(National Education Information System) has been completed. The NEIS consists of Nationwide service of NEIS, Business portal system of NEIS, Authentication management system and so on. Students, parents and civil petitioners handle civil affairs through Nationwide service of NEIS and teachers and persons of task conduct theirs business by accessing the Business portal system of NEIS. At this time, users have to obtain their certification from Authentication management system. Previous Studies were mainly focused on the evaluation about its performance according to the introduction of NEIS. But from now on there is a growing interest in security assessment and an efficient method for security improvement to check if NEIS works properly. Therefore, in this thesis, we'll propose an analytic framework in which security assessment is carried out after comprehending the fault structures through performing Fault Fishbone Analysis based on the Fault Tree Analysis. As a result of the system applied, the system had the highest rate of improvement to 47.7 percent.

• 한국통신학회논문지
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• 제31권9A호
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• pp.868-877
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• 2006

센서 네트워크에서 시각 동기 기술은 위치 추적, 암호화 기술에서의 타임 스탬프, 타 노드들로부터의 같은 이벤트 중복 감지 인식, 기록된 이벤트들의 발생 순서 구분 등 다양한 응용을 위해 필수적이다. 그리고 최근 센서 네트워크에서 신뢰성 및 고장 허용성에 대한 문제가 최근 연구의 주요한 영역으로 대두되고 있다. 본 논문에서는 네트워크 고장과 클럭 고장이라는 두가지 고장 모델을 가정하여 센서 네트워크에서 고장 허용 시각 관리 기법에 대해 제시한다. 제안한 기법은 노드 클럭의 불안정한 동요나 표류율에 심각한 변화가 발생하는 등의 고장이 발생했을 때 이러한 클럭 오류의 네트워크 전파를 제한하며 토폴로지 변화에 대응한다. 시뮬레이션 결과는 제안한 동기 기법이 기존의 TPSN과 비교하여 클럭 고장이 있을 때 동기화 비율이 $1.5{\sim}2.0$배 나은 성능을 보인다.

• Ocean Systems Engineering
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• 제9권3호
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• pp.261-285
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• 2019

Nowadays in offshore industry there are emerging hazards with vague property such as act of terrorism, act of war, unforeseen natural disasters such as tsunami, etc. Therefore industry professionals such as offshore energy insurers, safety engineers and risk managers in order to determine the failure rates and frequencies for the potential hazards where there is no data available, they need to use an appropriate method to overcome this difficulty. Furthermore in conventional risk based analysis models such as when using a fault tree analysis, hazards with vague properties are normally waived and ignored. In other word in previous situations only a traditional probability based fault tree analysis could be implemented. To overcome this shortcoming fuzzy set theory is applied to fault tree analysis to combine the known and unknown data in which the pre-combined result will be determined under a fuzzy environment. This has been fulfilled by integration of a generic bow-tie based risk analysis model into the risk assessment phase of the Risk Management (RM) cycles as a backbone of the phase. For this reason Fault Tree Analysis (FTA) and Event Tree Analysis (ETA) are used to analyse one of the significant risk factors associated in offshore terminals. This process will eventually help the insurers and risk managers in marine and offshore industries to investigate the potential hazards more in detail if there is vagueness. For this purpose a case study of offshore terminal while coinciding with the nature of the Caspian Sea was decided to be examined.

• 한국정보처리학회논문지
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• 제7권7호
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• pp.2169-2178
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• 2000

This paper proposes the structure of an agent and rules for fault detection and location on LAN. To find out a reason of critical fault incurred LAN, collision detection rule, error detection rule, broadcast detection rule, system location rule, and Internet application location rule ar shown. Also, the structure of multi-agent system and state transition diagram is portrayed to have connectivity with he set of rules. To verify availability of proposed rules, the process to find a faulty system is shown by monitoring and analyzing the LAN fault occurrences from the proposed set of rules. Such an rule based agent system is helpful to an Internet manager to solve a reason of fault and make ad decision from gathering management information.

• 전자통신동향분석
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• 제35권5호
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• pp.30-42
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• 2020

Unlike in previous generations of mobile technology, machine learning (ML)-based self-healing research trend are currently attracting attention to provide high-quality, effective, and low-cost 5G services that need to operate in the HetNets scenario where various wireless transmission technologies are added. Self-healing plays a vital role in detecting and mitigating the faults, and confirming that there is still room for improvement. We analyzed the research trend in self-healing framework and ML-based fault detection, fault diagnosis, and fault compensation. We propose that to ensure that self-healing is a proactive instead of being reactive, we have to design an ML-based self-healing framework and select a suitable ML algorithm for fault detection, diagnosis, and outage compensation.

• Journal of Power Electronics
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• 제10권1호
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• pp.34-42
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• 2010

Reliability is an important issue in cascaded H-bridge converters (CHB converters) because they use a high number of power semiconductors. A faulty power cell in a CHB converter can potentially lead to expensive downtime and great losses on the consumer side. With a fault-tolerant control strategy, operation can continue with the undamaged cells; thus increasing the reliability of the system. In this paper, the operating principles and the control method for a CHB multilevel rectifier are introduced. The influence of various faults on the CHB converter is investigated. The method of fault diagnosis and the bypassing of failed cells are explained. A fault-tolerant protection strategy is proposed to achieve redundancy in the CHB rectifier. The redundant H-bridge concept helps to deal with device failures and to increase system reliability. Simulation results verify the performance of the proposed strategy.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권12호
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• pp.534-543
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• 2006

BACnet(Building Automation and Control networks) is a standard data communication network protocol designed specifically for building automation and control systems. BACnet provides BACnet/IP Protocol for data communication through the Internet. BACnet device uses BBMD(BACnet Broadcasting Management Device) to deliver BACnet broadcast messages. In this study, we propose a fault tolerant BBMD in the BACnet/IP protocol. The fault tolerant BBMD improves the connectivity of BACnet/IP networks by inheriting the operation of original BBMD in the networks. The fault tolerant BBMD is implemented with added functions to the original BACnet/IP protocol so that it can provide backward compatibility with the original BACnet/IP devices. We examined the validity of the fault tolerant BBMD using an experimental model.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.36-41
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• 2008

Fault detection and diagnosis(FDD) system is beneficial in equipment management by providing the operator with tools which can help find out a failure of the system. An experimental study has been performed on fault detection and diagnosis method for a water chiller. Bayes classifier, which is one of classical pattern classifiers, is adopted in deciding whether fault occurred or not. FDD algorithm can detect refrigerant leak failure, when 20% amount of charged refrigerant for normal operation leaks from the water chiller. The refrigerant leak failure caused COP reduction by 6.7% compared with normal operation performance. When two kinds of faults, such as a decrease in the mass flow rate of cooling water and temperature sensor fault of cooling water inlet, are detected, COP is a little decreased by these faults.