• Nuclear Engineering and Technology
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• v.19 no.3
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• pp.186-191
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• 1987

In this paper, we suggest the simple and practical direct simulation method for the system reliability calculation In the aspect of system unavailability calculation, this method can simplify the calculation process by applying the hard-wired system fault tree. For the calculation purpose, we use the ESCAF which is developed by Mr. Laviron in France. As a consequence, we estimate the unavailability of OP$\Delta$T & OT$\Delta$T channel in W PWR plants as a value of 8.17576$\times$10$^{-9}$ from IEEE std. 500-1977's reference data. In our calculation, the processing time is no more than 25 sec.

• Asia pacific journal of information systems
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• v.30 no.2
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• pp.439-456
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• 2020

In online shopping, "out-of-stock" and "sold-out" are used to indicate product unavailability, and this unavailability and its effects on consumers' behaviors have been studied with great interest for practical purposes. However, few studies have specifically discussed out-of-stock and sold-out products in the same paper. We hypothesized that consumers might cognitively interpret items marked out-of-stock and sold-out differently, and in this paper, we studied these potential differences from the perspectives of consumers' emotions, behaviors, and loyalty based on the stimulus-organism-response framework. In order to explore the differences, we used a multi-method approach that consisted of experiments, surveys, and interviews. Specifically, we built an experimental website on which the same products were categorized as either out-of-stock or sold-out, and we measured the participants' emotions, attitudes, and intentions after the experiment. After two weeks, we conducted interviews to confirm our results and to learn more about consumers' everyday behavior. In the results, males and females demonstrated differences in emotion, behaviors, and loyalty with the interaction effects of an item's being marked out-of-stock versus sold-out. We found that the consumers demonstrated different levels of loyalty based on whether the item was marked out-of-stock or sold-out. We discuss the strategic implications of our findings.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1074-1079
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• 2013

Demand response(DR) is potential generation alternative to improve the reliability indices of system and load points. However, when demand resources scheduled in DR market fail to reduce demand, it can create new problems associated with maintaining a reliable supply. In this paper, a reliability model of demand resource is constructed considering customers' behaviors in the same form as conventional generation units, where availability and unavailability are associated with the simple two-state model. As a result, the generalized reliability model of demand resources is represented by multi-state model.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.81-83
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• 2005

The Reactor Protection System (RPS) is a very important system in a nuclear power plant because the system shuts down the reactor to maintain the reactor core integrity and the reactor coolant system pressure boundary if the plant conditions approach the specified safety limits. This paper describes the unavailability assessment of a digital reactor protection system using the fault tree analysis technique. The fault tree technique can be expressed in terms of combinations of the basic event failures. In this paper, a prediction method of the hardware failure rate is suggested for a digital reactor protection system. and applied to the reactor protection system being developed in Korea.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.562-569
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• 1996

원자력 발전소 기기들에 대한 점검주기와 점검방법은 기술지침서(Tech. Spec)의 점검요건(SR)에 명시되어 있는데 가압경수로(PWR) 원전의 경우 다중계통 기기 점검은 교번시험(Staggered Test) 방법으로 점검하도록 되어 있다. 그러나 그 동안의 원전 운전경험에 의하면 기기 점검 및 보수로 인하여 기기 마모. 발전소 정지. 운전원의 부담감, 방사선 피폭 등의 역효과(Adverse Effects)가 있는 것으로 알려져 있다. 본 연구에서는 다중계통(Multi-redundancy System)중 2/4 시스템에 대한 점검방법별 이용불능도(Unavailability)를 해석적 방법으로 구하고 점검 및 보수로 인한 기기 마모 역효과를 모델링하여 점검방법별로 적용하고 비교 분석하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.8
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• pp.1989-2002
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• 1996

In this paper, we describe several warm standby fault-tolerant models and their operation methods applicable to telephone switching control systems which have dual module structure and need high availability. Unavailabilities of the system implemented by four different methods for each model are computed by using the Markov state model, and then are compared for system performance evaluation. As the results ofsimulations, the warm standby model with triple processors is best in the aspect of data loss, while in most cases the warm standby model with doble processors based on no standby check method provides the highest system avaiability. Periodic changeover increases the system unavailability, but the preriodic standby check on standby module decreases the system unavailability of warm standby model with a single processor and with double processors. On the other hands, the variationas of warm standby model with a single processor and with double processors. On the other hand, the variations of data recovery time and personnel recovery rate have little effect on the system unavailtability.

• Nuclear Engineering and Technology
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• v.29 no.3
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• pp.211-217
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• 1997

Adverse effects caused by the surveillance test for the components of nuclear power plant involve plant transients, unnecessary wear, burden on licensee's time, and the radiation exposure to personnel along with the characteristics of each component. The optimization methodology of STI and AOT has been developed and applied to AFWPs of a reference plant. The approach proposed in this paper consist of the resole in minimal mean unavailability of the two-out-of-four system with adverse effects are analytically calculated for the example system. The surveillance testing strategy are given by the sequential test, the staggered test and the train staggered test which is a mined test scheme. In the system level, the sensitivity analyses for the STI and AOT, are performed for the measure of the system unavailability of the top event in the fault tree developed for the example system. This methodology may contribute to establishing the basis for the risk-based regulations.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2055-2057
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• 2003

This paper describes the results of RBD(Reliability Block Diagram) analysis of control rod control system, which is being developed as part of KNICS project. The results of RBD indicate unavailability of control cabinet for control rod control system. A purpose of RBB is to evaluate unavailability of control cabinet, identify the design drawbacks of control cabinet, and propose design improvement to a designer to help design the more reliable control rod control system. This RBD defines the logical interaction of failure within a system.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.481-482
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• 2004

• Proceedings of the Korean Nuclear Society Conference
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• 2003.05a
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• pp.89-89
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• 2003