• 한국컴퓨터정보학회논문지
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• 제22권4호
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• pp.1-8
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• 2017

In this paper, we propose a fault isolation system for device drivers of the Linux operating system. High availability systems impose stringent requirements upon Linux operating system. Especially device drivers can be a major source of operating system instability and many times contribute to system degradation and outages. The proposed fault isolation system identifies the occurrence of the memory-related faults in device driver and isolates it from the kernel. By operating at the early stage of the page fault handler in Linux kernel, the system detects which module causes fault and isolates it transparently from the remaining part of the kernel. By experiments, we show that the proposed system efficiently detects faults incurred by device driver, isolates the device driver and the process which accessed the driver module from the kernel.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권4호
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• pp.287-298
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• 2013

This paper presents a case study of PSD(Platform Screen Door) system assurance based on EN50126 life-cycle stage. By applying this system assurance, the accidents related to urban light transit railway especially that caused casualties could be reduced tremendously. This case study contributes significantly to the reliability, availability, maintainability and safety of the PSD system. Request For Proposal (RFP) of a rail road operator in which required by RAMS is prepared in which to ensure all system assurance activity and safety assessment are compulsory. The step-by-step activities and related deliverables are used which include functional analysis, FMECA, hazard identification analysis, system hazard analysis, maintainability analysis, FRACAS, and finally verification and validation of the system.

• 한국안전학회지
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• 제25권2호
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• pp.24-28
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• 2010

The nuclear power Plant onsite AC electrical power sources are required to supply power to the engineering safety facility buses if the offsite power source is lost. Typically, Diesel Generators are used as the onsite power source. The 125 VAC buses are part of the onsite Class 1E AC and DC electrical power distribution system. The DC power distribution system ensure the availability of DC electrical power for system required to shutdown the reactor and maintain it in a safety condition after an anticipated operational occurrence or a postulated Design Base Accident. Recently, onsite DC power supply system trip occurs the loss of system function. To obtain the performance such as reliability and availability, we analyzed the cause of battery charger trip and described the improvement of DC power supply system reliability. Finally, we provide reliability performance criteria of charger in order to ensure the probabilistic goals for the safety of the nuclear power plants.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1400-1402
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• 2004

The safety of staff, customers and of general Public in general viewed as one of the most important requirements in the urban transit. The maintenance computerization system for car of urban transit is a part of standardization and development of urban transit system. and We have been performed the establishment of maintenance computerization system from 2001 to 2005. The RAMS (reliability. availability. maintainability and safety) estimation for maintenance computerization system are utilized in a variety of computerization system for user's convenience and safety in maintenance. Ever since its inception though. the urban transit has searched for ways to improve reliability. availability. maintainability and safety of the railway subsystem. Provision of a reliable maintenance system include RAMS of the vehicles plays a very important role in achieving a safe system.

• 산업경영시스템학회지
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• 제28권2호
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• pp.117-124
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• 2005

This study tries to develop the models of measuring the level of product availability accommodated for features of specific customers dividing customers into VIP customers and general customers. Functions of costs that the models are composed of are cost of holding safety stock and cost of lost opportunities. The existing model of measuring the level of product availability which focused on cost of holding safety stock for VIP customers should be reinforced by considering cost of lost opportunities caused by general customers' quitting trades with a company. This study tries to present realistic solutions for problems in making decisions related to the total inventory. This study concludes that the model of the level of product availability meeting general customers' needs is more efficient according to increasing of a latent demand of the general customers who quit trades with a company and the cost of lost opportunities.

• 한국정보통신학회논문지
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• 제18권11호
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• pp.2634-2639
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• 2014

시스템 및 네트워크의 안정적인 서비스를 위한 기본적인 구조로 다양한 이중화 방식이 있다. 또한 시스템 및 네트워크의 성능을 분석하기 위하여 페트리네트에서부터 Stochastic Reward Net(SRN)에 이르기까지 다양한 성능 분석 모형이 존재한다. 본 논문에서는 정상 상태에서 하나의 액티브 서비스 유닛과 하나의 스탠바이 서비스 유닛을 가진 2N 이중화 방식을 SRN으로 모형화 한다. 성능 분석 소프트웨어인 추계적 페트리네트 패키지 SPNP를 사용하여 2N 이중화 방식의 가용도를 분석한다.

• 전기학회논문지
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• 제62권7호
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• pp.994-1002
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• 2013

This study suggests a generalized availability and safety evaluation model to evaluate the influences to the system's fault tolerant capabilities depending on automatic fault detection function such as the automatic periodic testings. The conventional evaluation model of automatic fault detection function deals only with the self diagnostics, and supposes that the fault detection coverage of self diagnostics is always constant. But all of the fault detection methods could be degraded. For example, the periodic surveillance test has the potential human errors or test equipment errors, the self diagnostics has the potential degradation of built-in logics, and the automatic periodic testing has the potential degradation of automatic test facilities. The suggested evaluation models have incorporated the loss or erroneous behaviors of the automatic fault detection methods. The availability and the safety of each module of the safety grade platform have been evaluated as they were applied the automatic periodic test methodology and the fault tolerant evaluation models. The availability and safety of the safety grade platform were improved when applied the automatic periodic testing. Especially the fault tolerant capability of the processor module with a weak self-diagnostics and the process parameter input modules were dramatically improved compared to the conventional cases. In addition, as a result of the safety evaluation of the digital reactor protection system, the system safety of the digital parts was improved about 4 times compared to the conventional cases.

• 대한산업공학회지
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• 제21권1호
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• pp.17-32
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• 1995

The objective of this study is to develop a general design and performance evaluation model for the system designers in the initial design phase of the integrated automatic manufacturing system based on the RAM(Reliability, Availability and Maintainability) and life cycle cost(LCC). The methodology proposed in this research includes the following two stages. First, a deterministic approach to the solution of optimal work station arrangement for the initial system configuration is considered under the assumption that the system availability is one(no failure and maintenance), and then a stochastic simulation model based on RAM and LCC is developed. Using the results of these two stage simulation, a system performance index(SPI) was developed for the performance evaluation of the proposed system. Also a computer program is developed.

• 동굴
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• 제80호
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• pp.11-19
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• 2007

Most studies in the past in testing and benchmarking on Intrusion Detection System (IDS) were conducted as comparisons, rather than evaluation, on different IDSs. This paper presents the evaluation of the performance of one of the open source IDS, snort, in an inexpensive high availability system configuration. Redundancy and fault tolerance technology are used in deploying such IDS, because of the possible attacks that can make snort exhaust resources, degrade in performance and even crash. Several test data are used in such environment and yielded different results. CPU speed, Disk usage, memory utilization and other resources of the IDS host are also monitored. Test results with the proposed system configuration environment shows much better system availability and reliability, especially on security systems.

• 한국신뢰성학회지:신뢰성응용연구
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• 제5권3호
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• pp.373-379
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• 2005

In many cases, it is more practical and economical to repair a system than to replace the whole system or to perform a complete overhaul when the system fails. Two basic replacement policies were proposed by Barlow and Hunter(1960) and Morimura (1970), in which the minimal repair times are identically distributed. But, as Lam(1988) pointed out, in many cases of deteriorating system, in view of ageing and cumulative wear, the repair time will tend to be longer and longer. In this note, the two basic replacement policies are considered for a repairable system with linearly increasing repair times. Optimal policies, which maximize the steady state availability of the system, are obtained for the Weibull failure rate case.