• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.143-148
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• 2010

A Statistical methods are used to determine the reliability of a Fuel Boost Pump for aviation. Failures are referenced from failure reports. The failure-free periods between successive failure events are evaluated in the form of weibull distribution. The results of analysis were calculated shape factor, scale parameter and mean time to failure. It found that the reason of failure is wear-out period.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.3
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• pp.609-618
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• 2024

System reliability prediction in the development stage is increasingly crucial to reliability growth management to satisfy its target reliability, since modern system usually takes a form of complex composition and various complicated functions. In most cases of development stage, however, the information available for system reliability prediction is very limited, making it difficult to predict system reliability more precisely as in the production and operating stages. In this study, a system reliability prediction process is considered when the reliability-related information such as SIL (Safety Integrity Level) and MTTFd (Mean Time to Dangerous Failure) is available in the development stage. It is suggested that when the SIL or MTTFd of a system component is known and the field operational data of similar system is given, the reliability prediction could be performed using the scaling factor for the SIL or MTTFd value of the component based on the similar system's field operational data analysis. Predicting a system reliability is then adjusted with the conversion factor reflecting the temperature condition of the environment in which the system actually operates. Finally, the case of applying the proposed system reliability prediction process to a high performance mooring platform is dealt with.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.48-55
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• 2024

The safety-related raw water system's strong operational condition supports the radiation defense and biological shield of nuclear plant containment structures. Gaps and failures in maintaining proper working condition of main equipment like pump were among the most common causes of unavailability of safety related raw water systems. We integrated the advanced data analytics tools to evaluate the maintenance records of water systems and gave special consideration to deficiencies related to pump. We utilized maintenance data over a three-and-a-half-year period to produce metrics like MTBF, MTTF, MTTR, and failure rate. The visual analytic platform using tableau identified the efficacy of maintenance & deficiency in the safety raw water systems. When the number of water quality violation was compared to the other O&M deficiencies, it was discovered that water quality violations account for roughly 15% of the system's deficiencies. The pumps were substantial contributors to the deficit. Pump availability was predicted and optimized with real time data using response surface method. The prediction model was significant with r-squared value of 0.98. This prediction model can be used to predict forth coming pump failures in nuclear plant.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.3
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• pp.1-10
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• 1995

In this paper, a fault-tolerant Mini-MAP system with high reliability is proposed. For fault-tolerance, the LLC sublayer, MAC sublayer, and physical layer of the Mini-MAP system are dualized. The detection of faults, the replacement of the failed network, and the management of the network are three major functions required for the dualization, and they are performed by ESM(Error Supervisory Machine), EMM(Error Management Machine), and NMM(Network Management Machine) of the proposed fault-tolerant Mini-MAP system, respectively. The ring maintenance function of the MAC sublayer is used for the detection of the faults. In the proposed fault-tolerant Mini-MAP system, the data are received from both of the dualized networks and transmitted to the selected one of the two. We analyze the reliability and the MTTF(Mean Time To Failure) of the proposed fault-tolerant Mini-MAP system and show that it has better performance compared to a general Mini-MAP system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.25-30
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• 2004

This paper gives an assessment criteria and average failure lifetime prediction for power supply of electrodeless fluorescent lamp. The paper present electric appliance safety standard and performance standard for power supply of electrodeless fluorescent lamp. also, It presents the Failure Rate or Mean Time To Failure(MTTF) for power supply of electrodeless fluorescent lamp. We suggest the assessment criteria and improve methods of the reliability on the design basis for the electrodeless fluorescent system.

• Journal of the Korea Society for Simulation
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• v.9 no.2
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• pp.51-61
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• 2000

In recent years, significant advances in computers and communication technologies have made multimedia services feasible. As a result, various queueing models and cost models on architecture and data placement for multimedia server have been proposed. However, most of these models do not evaluate dependability of systems. In the design phase of a system, simulation is an important experimental means for performance and dependability analysis. Fault injection simulation has been used in evaluation of dependability metric. In this paper, we develop fault injection simulation model to analyze dependability of parallel video servers. In addition, we evaluate reliability and MTTF(Mean Time To Failure) of systems by using the simulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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• pp.414-416
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• 2013

As the usage of the electric power train increases, the importance of the control network between the electric control devices grows. IEC proposed a revision of IEC-61375, a standard of the networking among electric devices within a train, to adopt Ethernet as a backbone of train network. This paper performed the reliability analysis of three configurations of Ethernet-based networking within a electric power train that are recommended in IEC-61375 standard. The analysis results show that MTTF(mean time to failure) of the redundant configuration is 20,086 hours, which is a about 3 times longer than the linear configuration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12B
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• pp.2016-2024
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• 2000

본 논문에서는 결함의 영향을 받지 않고 동작할 수 있는 AVTMR(All Voting Triple Modular Redundancy) 시스템을 개발하였으며, MILSPEC-217F에 기반을 둔 고장율을 계산하여 AVTMR과 SS(Single System) 시스템을 비교 및 평가하였다. 설계된 시스템은 MC68000을 기반으로 한 3중화된 다수결 보터(Triplicated Majority Voter)를 이용하여 시스템을 개발하였다. 본 논문에서는 시스템의 신뢰도(Reliability), 가용도(Avaliability), 유지보수도(Maintainability)를 마코브 모델(Markov model)로 평가하였으며, 또한 시스템의 MTTF(Mean Time to Failure)를 계산하여 시스템의 수명을 구하였고, 설계된 AVTMR 시스템이 SS(Single System)보다 전체 시스템 평가에서 우수한 특성을 가진다는 것을 시뮬레이션을 통해 알 수 있었다. 또한, AVTMR 시스템은 결함을 허용(Fault tolerant)하는 시스템 특성을 가지기 때문에, 인간의 생명과 관련된 철도 시스템, 선박 시스템이나 항공기 시스템에 적용될 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.6A
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• pp.1067-1077
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• 2001

본 논문에서는 결함의 영향을 받지 않고 동작할 수 있는 AVTMR(All Voting Triple Modular Redundancy) 시스템과 듀얼 듀플렉스(Dual-duplex) 시스템을 설계하고, 각 시스템의 평가를 통하여 RAMS(Reliability, Avaliability, Maintainability, Safety)를 비교하였다. ABTMR 시스템은 3중화된 보터(voter)를 사용하여 설계를 하였으며, 듀얼 듀플렉스 시스템은 비교기(comparator)를 이용하여 시스템을 설계하였다. 각 시스템은 버스 레벨로 데이터를 비교하도록 설계하였으며, 시스템 평가를 위해서 소자의 고장율은 MILSPEC-217F에 기반을 두고 RELEX6.0을 이용하였고, 마코브 모델(Markov model)을 이용하여 시스템의 RAMS를 평가하였다. 본 논문에서는 각 시스템을 MC68000을 기반으로 설계하여, 각각 시스템에 사용되는 비용 및 시스템이 어느 부분에서 선호될 수 있는가를 RAMS 및 MTTF(Mean Time To Failure)를 통하여 선택할 수 있는 기반을 제시하도록 나타내고 있다. 이러한 AVTMR이나 듀얼 듀플렉스 시스템(dual-duplex system)은 결함 허용 시스템(fault tolerant system)으로 인간의 생명과 직접적인 관련이 있는 고속철도 시스템이나 항공기 시스템에 적용될 수 있다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.2
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• pp.34-40
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• 2003

This paper gives an assessment criteria and reliability improvement for high frequency power supply of high efficacy electrodeless fluorescent lamp. The electrodeless fluorescent lamp system consist of electrodeless fluorescent lamp, high frequency power supply and lighting fixtures. The high frequency power supply has a shortest life at the system. Therefore It is need th assess the Failure Rate or mean Time To Failure(MTTF) for the high frequency power supply of electrodeless fluorescent lamp system and improve the reliability at design. We suggest the assessment criteria and improve methods of the reliability on the design basis for the electodeless fluorescent system.