• Structural Engineering and Mechanics
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• v.63 no.6
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• pp.799-808
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• 2017

Failure of a redundant long-span bridge is often described by innumerable failure modes, which make the structural system reliability analysis become a computationally intractable work. In this paper, an innovative procedure is proposed to efficiently identify the dominant failure modes and quantify the structural reliability for a long-span bridge system. The procedure is programmed by ANSYS and MATLAB. Considering the correlation between failure paths, a new branch and bound operation criteria is applied to the traditional stage critical strength branch and bound algorithm. Computational effort can be saved by ignoring the redundant failure paths as early as possible. The reliability of dominant failure mode is computed by FORM, since the limit state function of failure mode can be expressed by the final stage critical strength. PNET method and FORM for system are suggested to be the suitable calculation method for the bridge system reliability. By applying the procedure to a CFST arch bridge, the proposed method is demonstrated suitable to the system reliability analysis for long-span bridge structure.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2915-2923
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• 2022

There is an increasing interest in passive safety systems to minimize the need for operator intervention or external power sources in nuclear power plants. Because a passive system has a weak driving force, there is greater uncertainty in the performance compared with an active system. In previous studies, several methods have been suggested to evaluate passive system reliability, and many of them estimated the failure probability using thermal-hydraulic analyses and the Monte Carlo method. However, if the functional failure of a passive system is rare, it is difficult to estimate the failure probability using conventional methods owing to their high computational time. In this paper, a procedure for the application of the Chernoff bound to the evaluation of passive system reliability is proposed. A feasibility study of the procedure was conducted on a passive decay heat removal system of a micro modular reactor in its conceptual design phase, and it was demonstrated that the passive system reliability can be evaluated without performing a large number of thermal-hydraulic analyses or Monte Carlo simulations when the system has a small failure probability. Accordingly, the advantages and constraints of applying the Chernoff bound for passive system reliability evaluation are discussed in this paper.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1991.10a
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• pp.145-149
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• 1991

In this paper, an algorithm is proposed to analyze the approximating reliability of the capacity considered communication networks. In the case ofthe former methods to evaluate the source-to-termianl node reliability, it is very difficult to contract and delete the jointed terms in the simple path group. Therefore, the reliability bounds are used and compared to the exact reliability by TURBO PROLOG, the natural lanquage of artficial intelligence. In the reliability bounds, the upper bound used the valid cutset that isthe group of simple path and the lower bound used the minimal cutset by complement operation and the esact reiability is compared to this reliability bounds.

• Journal of Korean Society for Quality Management
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• v.22 no.1
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• pp.205-213
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• 1994

We construct a new lower bound of Cramer-Rao type for the median-unbiased estimator in the presence a nuisance parameter. We also identify useful necessary and sufficient conditions for the attainability of the lower bound. Some applications including the analysis of censored reliability data are considered as examples.

• Journal of Digital Contents Society
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• v.6 no.1
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• pp.7-12
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• 2005

The purpose of this study is to study the relability of degree 2 ICR(Interleaved Cydic Ring) network and to compare with the other rings. Two node reliability is the probability that source node communicates with the destination node through a specified time interval for ICR network. The impact for change of failure rate is studied for ICR network for small size of network, the exact value of reliability is calculated but the approximation of average reliability general function from upper bound and lower bound reliability is obtained for large size of it. The reliability of ICR network is compared with it of the other rings according to changing the cycle value of ICR.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.115-124
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• 1993

A structural system reliability analysis is studied for the safety assessment of midship section. Probabilistically dominant collapse modes are generated by Element Replacement Method and Incrimental Load Method. In order to avoid generating the same modes repeatedly, it is branched at final plastic hinge. Using first and second order bound methods, system failure probability of midship section is computed and compared with deterministic load factor method to show the usefulness of the proposed method.

• Computational Structural Engineering : An International Journal
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• v.1 no.2
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• pp.81-87
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• 2001

A framework for reliability analysis of structural components and systems under conditions of statistical and model uncertainty is presented. The Bayesian parameter estimation method is used to derive the posterior distribution of model parameters reflecting epistemic uncertainties. Point, predictive and bound estimates of reliability accounting for parameter uncertainties are derived. The bounds estimates explicitly reflect the effect of epistemic uncertainties on the reliability measure. These developments are enhance-ments of second-moment uncertainty analysis methods developed by A. H-S. Ang and others three decades ago.

• Journal of Korean Society for Quality Management
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• v.26 no.3
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• pp.71-81
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• 1998

In reliability analysis, the time difference between the expected next failure time and the current failure time or the Mean Time Between Failure(MTBF) is of significant interest. Until recently, in reliability growth studies, the reciprocal of the intensity function at current failure time has been used as being equal to MTBE($t_n$)at the n-th failure time $t_n$. That is MTBF($t_n$)=l/$\lambda (t_n)$. However, such a relationship is only true for Homogeneous Poisson Process(HPP). Tsokos(1995) obtained the upper bound and lower bound for the MTBF($t_n$) and proposed an estimator for the MTBF($t_n$) as the mean of the two bounds. In this paper, we provide the estimator for the MTBF($t_n$) which does not depend on the value of the shape parameter. The result of the Monte Carlo simulation shows that the proposed estimator has better efficiency than Tsokos's estimator.

• Child Health Nursing Research
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• v.21 no.2
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• pp.160-167
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• 2015

Purpose: This study was done to evaluate the Lasater Clinical Judgement Rubric for use with Korean nursing students. Methods: A methodological study was used to validate the rubric developed by Lasater to assess clinical judgment during nursing simulation. Participants were 34 nursing students at K University in Seoul. Between February and May, 2012, analysis was done of 91 video clips recording performance during simulation. Results: Findings showed reliability and validity of the rubric. For internal consistency, Cronbach's ${\alpha}$ score was .884 and intraclass correlation coefficient was .839, which established reliability. The rubric was validated using the exploratory factor analysis and content validity. The content validity score was 83%, establishing the appropriateness and readiness of the tool. Factor analysis showed that noticing, responding, and reflecting domains had Eigen values of 2.669, 1.991, and 2.912, respectively and were bound, but unlike the original tool in which four factors noticing, interpretation, responding, and reflecting domains were bound. Conclusion: Results of the study indicate that the rubric shows acceptable reliability and validity in Korean nursing students. This evaluation tool for nursing simulation allows nursing faculty to objectively evaluate students' clinical judgment as well as students to reflect on their clinical judgment process during simulation.

• The Korean Journal of Rehabilitation Nursing
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• v.18 no.2
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• pp.145-152
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• 2015

Purpose: The purpose of this study was to evaluate the reliability and validity of the clinical judgement rubric on simulation practice with a post-operative rehabilitation case. Methods: Methodological study design was used to evaluate the reliability and validity of the clinical judgement rubric on simulation practice. The participants were 35 students in a college of nursing. Results: There were showed reliability and validity of the clinical judgement rubric on simulation practice with a post-operative rehabilitation case. In terms of internal consistency, the Cronbach's ${\alpha}$ for all columns was .821. Factor analysis showed that planning, intervention and evaluation domains with Eigen values of 69.87% were bound, unlike the original tool where four factors including noticing, interpretation, responding and reflecting domains were bound. Convergent validity was established by the correlation between the total clinical judgement score and critical thinking disposition before and after simulation practice. Discriminative validity was established by the correlation between the total clinical judgement score and simulation effectiveness score. Conclusion: The findings of this study suggested that clinical judgement rubric on simulation practice is reliable. Repeated studies are needed to objectively evaluate the clinical judgement rubric of simulation practice for applying various clinical situations.