• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.3-20
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• 2006

The following lessons have been learned from the application of reliability methods in the practice of geotechnical engineering: 1. Establishing Goals Is Important; 2. Mitigating Consequences Can Be Effective; 3. Performance Depends on Systems; 4. Physical Factors Are Important in Statistical Models; 5. Too Much and Too Little Conservatism Are Both Problems; 6. Value of Information Depends on Decision Making; and 7. Effective Communication Is Essential. While the potential for application of reliability methods in the future is unlimited, there are major needs related to each of these lessons that will have to be addressed in order to realize this potential.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.116-118
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• 2003

This paper describes the contingency analysis methods which are used in the transmission reliability program, TPLAN. Reliability criterion, reliability assessment, ranking methods, and screening methods are discussed. In addition, a simple 25-bus system was tested with TPLAN and its analyses are presented in this paper.

• Industry Promotion Research
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• v.8 no.1
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• pp.111-117
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• 2023

Sampling inspection methods for quality control have been proposed a lot in the industry. However, the sampling inspection method for reliability, which is a quality over time, has been relatively less presented, and there are not many literatures that are clearly summarized. Therefore, this paper focuses on the reliability conformity test to verify that the reliability evaluation scale value of the target is satisfied during the reliability test. To this end, first, we look at the conditions that both consumers and producers can satisfy in terms of the OC curve and find out what sampling methods satisfy the desired level of producer risk and consumer risk. Next, two methods of the reliability sampling methods such as attribute and variable reliability sampling methods are examined. Specifically, the attribute reliability sampling method is a form of sampling plan where n samples are tested for a certain period of T hours and the lot is accepted if the number of failures is less than or equal to a certain number c. On the other hand, the variable reliability sampling method is a form of sampling plan where the lot is accepted if the reliability evaluation scale such as MTBF satisfies a certain standard. Both sampling plans may also use inspection tables.

• Physical Therapy Korea
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• v.20 no.3
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• pp.74-80
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• 2013

The purpose of this study was to determine the reliability of distance measurements from the medial border of the scapula to the spinous process of the thoracic vertebrae when obtained using tape and photography measurements. The study included 20 healthy subjects (10 males, 10 females); for a total of 40 scapula measurements. The distance measurements made using tape or photography methods were conducted with the subject in a standing position. Repeated tape and photography measurements were conducted in two sessions on different days by two examiners to assess the inter-rater and intra-rater reliability of the two methods. The reliability of scapular distance measured using tape and photography methods was tested using intraclass correlation coefficients (ICC(3,1)) and the standard error of measurement (SEM). The inter-rater reliability of the tape measurement method was excellent (ICC=.77) and the intra-rater reliability was fair to good (ICC=.74). The inter-rater and intra-rater reliabilities of the photography measurement method were excellent (ICC=.76 and .76 respectively). Our results suggest that photography measurement is an objective and qualitative measurement tool for scapular distance measurements.

• Structural Engineering and Mechanics
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• v.85 no.3
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• pp.369-379
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• 2023

Reliability-Based Design Optimization (RBDO) is an appropriate framework for obtaining optimal designs by taking uncertainties into account. Large-scale problems with implicit limit state functions and problems with discrete design variables are two significant challenges to traditional RBDO methods. To overcome these challenges, this paper proposes a hybrid method to perform RBDO of structures that links Firefly Algorithm (FA) as an optimization tool to advanced (finite element) reliability methods. Furthermore, the Genetic Algorithm (GA) and the FA are compared based on the design cost (objective function) they achieve. In the proposed method, Weighted Simulation Method (WSM) is utilized to assess reliability constraints in the RBDO problems with explicit limit state functions. WSM is selected to reduce computational costs. To performing RBDO of structures with finite element modeling and implicit limit state functions, a First-Order Reliability Method (FORM) based on the Direct Differentiation Method (DDM) is utilized. Four numerical examples are considered to assess the effectiveness of the proposed method. The findings illustrate that the proposed RBDO method is applicable and efficient for RBDO problems with discrete and continuous design variables and finite element modeling.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1642-1647
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• 2007

The aim of this research is to implement a design framework based on reliability analysis and make it possibly used for a reliable and robust design under uncertainties. Different types of reliability methods and algorithms are programmed to explore their characteristics. In our work, RIA and the PMA are employed for formulating the reliability analysis problems. A number of reliability methods are introduced in this program such as FORM, AMV/AMV+ and MCS. Reliability analysis can be easily performed with this tool box only if a drive file is ready to run. Users need to select random design variables and define their distributions and correlation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.16-23
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• 2006

Recently the design of multi-stage gear drive is being highly concerned. Until now, since the researches of gear drive are focused on the design for satisfying safety factor, the reliability evaluation of multi-stage gear drive is not included. In this paper, the life and reliability models of multi-stage gear drive are proposed using methods of probability and statistics. The life and reliability of the multi-stage gear drive have been evaluated, which is based on the life and reliability of each stage gear drive. The pinion and gear lives of each stage are calculated using the Lundberg-Palmgren theory and the Weibull failure distribution. These lives are combined using methods of probability and statistics to produce a life and reliability model of multi-stage gear drive.

• Journal of the Korea Safety Management & Science
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• v.9 no.2
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• pp.161-169
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• 2007

This paper presents three methods for expression of reliability measures for large and small data. First method is to express parametric estimation of cardinal reliability measure data for large sample, which requires numerous sample. Second is to obtain nonparametric distribution classification of ordinal reliability measure data for small sample. However it is difficult for field user to understand this method. Last method is to acquire parametric estimation of ordinal reliability measure data for small data. Because this method requires small sample and is comprehensive, we recommend this one among the proposed methods. Various reliability rank measures are presented.

• Nuclear Engineering and Technology
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• v.40 no.5
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• pp.375-386
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• 2008

Conventional static reliability analysis methods are inadequate for modeling dynamic interactions between components of a system. Various techniques such as dynamic fault tree, dynamic Bayesian networks, and dynamic reliability block diagrams have been proposed for modeling dynamic systems based on improvement of the conventional modeling methods. In this paper, we review these methods briefly and introduce dynamic nodes to the existing reliability graph with general gates (RGGG) as an intuitive modeling method to model dynamic systems. For a quantitative analysis, we use a discrete-time method to convert an RGGG to an equivalent Bayesian network and develop a software tool for generation of probability tables.

• Proceedings of the Safety Management and Science Conference
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• 2007.04a
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• pp.335-346
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• 2007

This paper introduces reliability stress screening(RSS) for electronic hardware and components. This study also shows reliability centered maintenance(RCM), and reliability growth models. Moreover, this paper presents goodness-of-fit tests and estimation methods of power law model.