• Nuclear Engineering and Technology
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• v.46 no.4
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• pp.481-488
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• 2014

An analysis of the uncertainty quantification related to LBLOCA using the Monte-Carlo calculation has been performed and compared with the tolerance level determined by the Wilks' formula. The uncertainty range and distribution of each input parameter associated with the LOCA phenomena were determined based on previous PIRT results and documentation during the BEMUSE project. Calulations were conducted on 3,500 cases within a 2-week CPU time on a 14-PC cluster system. The Monte-Carlo exercise shows that the 95% upper limit PCT value can be obtained well, with a 95% confidence level using the Wilks' formula, although we have to endure a 5% risk of PCT under-prediction. The results also show that the statistical fluctuation of the limit value using Wilks' first-order is as large as the uncertainty value itself. It is therefore desirable to increase the order of the Wilks' formula to be higher than the second-order to estimate the reliable safety margin of the design features. It is also shown that, with its ever increasing computational capability, the Monte-Carlo method is accessible for a nuclear power plant safety analysis within a realistic time frame.

• Nuclear Engineering and Technology
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• v.42 no.2
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• pp.163-174
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• 2010

As pointed out in the OECD BEMUSE Program, when a high computation time is taken to obtain the relevant output values of a complex physical model (or code), the number of statistical samples that must be evaluated through it is a critical factor for the sampling-based uncertainty analysis. Two alternative methods have been utilized to avoid the problem associated with the size of these statistical samples: one is based on Wilks' formula, which is based on simple random sampling, and the other is based on the conventional nonlinear regression approach. While both approaches provide a useful means for drawing conclusions on the resultant uncertainty with a limited number of code runs, there are also some unique corresponding limitations. For example, a conclusion based on the Wilks' formula can be highly affected by the sampled values themselves, while the conventional regression approach requires an a priori estimate on the functional forms of a regression model. The main objective of this paper is to assess the feasibility of the ACE-RSM approach as a complementary method to the Wilks' formula and the conventional regression-based uncertainty analysis. This feasibility was assessed through a practical application of the ACE-RSM approach to the LOFT L2-5 LBLOCA PCT uncertainty analysis, which was implemented as a part of the OECD BEMUSE Phase III program.

• The Journal of Korean Medicine
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• v.31 no.5
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• pp.41-59
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• 2010

Objective: Headache is one of the most common symptoms in primary medical care. The purpose of this study was to support medical treatment by consideration of a new CTTH (chronic tension-type headache) oriental medical diagnosis index. Methods: An Oriental medical diagnosis questionnaire was administered to a CTTH group, migraine group and normal group. The result was classified by using LDA, CART, factor diagnosis and tested in comparison with the original diagnosis. Also, weighting method based on expert opinions was done. Results: 1. The result analyzed by using LDA has an accuracy of 93.9% in comparison with the original diagnosis. 2. High accuracy showed when the test was performed with about 35 significant questions and four questions selected based on SPSS Wilks' lambda. 3. There was accuracy of 90.9% when differentiation was performed by using CART compared with original diagnosis. 4. 10 factors has a high initial value after factor analysis, consisting of questions to the similar differentiation. 5. Diagnosis formula of headache was made by using weighting method based on expert opinions. Conclusion: Oriental medical diagnosis questionnaires make it possible to classify headaches significantly. The study about weighting method of CTTH can make it possible to classify symptoms more accurately.