• International Journal of Reliability and Applications
• /
• 제12권1호
• /
• pp.49-60
• /
• 2011

The geometric process (GP) has been widely used for modeling failure and repair time sequences of repairable systems. The GP is mathematically tractable but restrictive in reliability applications since it actually assumes that the mean function of inter-failure times sequence asymptotically decreases to zero; and the mean function of successive repair times sequence asymptotically increases to infinity. This is generally unrealistic from an engineering perspective. This paper presents three extended GP models for modeling reliability deterioration and improvement (or growth) process. The extensions maintain the advantage of mathematical tractability of GP model. Their usefulness and appropriateness are illustrated with three real-world examples.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 춘계학술대회 논문집
• /
• pp.941-946
• /
• 2007

In this paper, as the step to assess and enhance the reliability of Korean Tilting Train eXpress (T.T.X), Door system is selected and reliability analysis is carried out. The door system is classified into subsystems and functional block diagrams and reliability block diagrams are drawn.Expessions for evaluating the reliability are derived and Mean Kilometer between Service Failure is calculated using the trial track test results. The calculation result show reliability growth of proposed system. This paper developed RAMS to make a door system of T.T.X. (Tilting Train eXpress) with maximum operation speed of 180 km/h.

• Journal of Information Technology Applications and Management
• /
• 제13권4호
• /
• pp.1-12
• /
• 2006

Many software reliability growth models(SRGM) have been proposed since the software reliability issue was raised in 1972. The technology to estimate and grow the reliability of developing S/W to target value during testing phase were developed using them. Most of these propositions assumed the S/W debugging testing efforts be constant or even did not consider them. A few papers were presented as the software reliability evaluation considering the testing effort was important afterwards. The testing effort forms which have been presented by this kind of papers were exponential, Rayleigh, Weibull, or logistic functions, and one of these 4 types was used as a testing effort function depending on the S/W developing circumstances. I propose the methology to evaluate the SRGM using least square estimator and maximum likelihood estimator for those 4 functions, and then examine parameters applying actual data adopted from real field test of developing S/W.

• 대한치과기공학회지
• /
• 제40권3호
• /
• pp.151-162
• /
• 2018

Purpose: The main purpose of this study is to develop assessment measures for the quality of service for dental labs. Methods: In order to construct the measure of service quality assessment for dental labs, relevant modifications were extracted around theoretical studies, and the survey was conducted on dental technician workers through internet survey. final scale questions were extracted through exploratory factor analysis and confirmed factor analysis of measurement variables, the demographic characteristics of the subjects and the perceptual difference of dental labs were analyzed for the extracted variables. Results: The final five variants of the interactive factor analysis that include the ability to change employee growth, reliability, responsiveness, materiality, interoperability, confirmatory factor analysis excludes variations in employee growth wages, welfare benefits, by changing its name to network capabilities, the quality of service factors for the final dental labs consisted of five variations: network competence, reliability, responsiveness, materiality and interoperability. Conclusion : The service quality of the dental labs showed that the reliability of the product related to the dental materials and the product production responsiveness related to the production order, the Materiality of the materials and equipment of the dental labs, the Interoperability responsiveness related to dental orders, And the importance of network capability to form a mutual network.

• 한국건축시공학회지
• /
• 제13권2호
• /
• pp.148-158
• /
• 2013

Generally, building construction projects have a complex decision-making process because of the participation of various agents. In this situation, a final decision is arrived at by relying on subjective judgments based on the experience of project participants. For this reason, a method of assessing the objectivity of opinions is needed. In previous studies, the multi-criteria decision making method was applied to arrive at a final decision objectively, but this method has a limitation, in that the experience of each decision maker is not considered differently in the decision making process. Therefore, this study proposed a theoretical model using the S-shaped growth curve and regression analysis by building construction project type to quantitatively estimate decision-making reliability according to the experience of individual project participant`s. The developed model could be added to the Multi-criteria decision making method, and secure the objectivity and reliability of project participants' final opinion.

• 대한조선학회논문집
• /
• 제30권2호
• /
• pp.161-176
• /
• 1993

본 논문에서는 주어진 상황에 맞추어 적절한 수준에서 건전성평가를 수행하기 위하여, 개정된 BSI PD 6493의 3단계 평가방법에 균열성장효과를 고려한 건전성 평가방법과 균열의 안정성장을 엄밀히 고려할 수 있는 안정성 평가방법(stability assessment method:SAM)과 더불어 소성 붕괴를 평가하는 극한하중해석을 고려한 건전성 평가방법을 정식화하였다. 또한 신뢰성이론 중 2차 모멘트방법을 사용하여, center cracked panel(CCP) 시편과 관통균열을 갖는 파이프에 대하여, 신뢰성해석에 의한 건전성 평가를 수행하였다. 신뢰성해석을 수행하는데 필요한 확률변수들의 통계적 특성은 지금까지 보고된 그들 변수들의 실험자료와 통계해석의 결과들을 이용하였다. 또 기존의 신뢰성해석에서 정확한 파괴확률을 구할 수 있는 Monte Carlo 방법을 사용하여, 본 논문의 유용성을 검토하였다.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제54권6호
• /
• pp.396-402
• /
• 2005

The software reliability growth model(SRGM) has been developed in order to evaluate such measures as remaining fault number, fault rate, and reliability for the developing stage software. Most of the study literatures assumed that this detecting efficiency was perfect. However the actual fault detecting is generally imperfect, and widely known to many persons. It is not easy to develop and remove the fault existing in the software because the fault finding is difficult, and the exact solving method also not easy, and new fault may be introduced depending on the tester's capability. There, the fault removing efficiency influences the software reliability growth or developing cost of software. It is a very useful measure throughout the developing stage, much helpful for the developer to evaluate the debugging efficiency, and evaluate additional workload. Hence, the study for the imperfect debugging is important in point of software reliability and cost. This paper proposes that the fault debugging is imperfect and new fault may be introduced for the developing software during the developing stage.

• 한국재료학회지
• /
• 제15권1호
• /
• pp.54-60
• /
• 2005

Recently a lots of problems have observed in high densified and high integrated electronic components. One of them is ion migration phenomena, which induce the electrical short of electrical circuit. ion migration phenomena has been observed in the field of exposing the specific environment and using for a long tin e. This study was evaluated the generation time of ion migration and was investigated properly test method through water drop test and high temperature high humidity test. Also we observed direct causes and confirmed generation mechanism of dendritic growth as we reproduced the ion migration phenomena. We utilized PCB(printed circuit board) having a comb pattern as follows 0.5, 1.0, 2.0 mm pattern distance. Cu, SnPb and Au were electroplated on the comb pattern. 6.5 V and 15 V were applied in the comb pattern and then we measured the electrical short time causing by ion migration. In these results, we examined a difference of ion migration time depending on pattern materials, applied voltage and pattern spacing of PCB conductor.

• 항공우주기술
• /
• 제2권1호
• /
• pp.205-212
• /
• 2003

신뢰성이란 부품이나 시스템이 얼마나 오랫동안 안심하고 사용할 수 있는가를 정량적 수치로 표현하는 미래의 품질 개념으로 앞으로 제품의 국제적인 경쟁력을 갖추기 위하여 필수적으로 요구되는 기술이다. 국내에서도 제품의 신뢰성 향상에 대한 관심과 필요성이 더욱 고조됨에 따라, 정부에서도 세계적 수준의 신뢰성 평가 인프라를 구축하기 위해 “신뢰성 향상 기반 구축사업”을 적극적으로 추진하고 있으며, 대학, 연구기관 및 전자, 자동차, 중공업 등 수출업체에서 신뢰성에 관한 연구 및 시험평가센터를 설립하여 본격적으로 신뢰성 문제를 다루고 있다. 본 논문에서는 신뢰성 향상 사업에 대한 국내의 현황을 소개하고 항공우주분야에 대한 신뢰성 인증제도 도입의 필요성에 대하여 검토하였다.

• International Journal of Reliability and Applications
• /
• 제8권2호
• /
• pp.153-173
• /
• 2007

Wood-plastic composites (WPC) are gaining market share in the building industry because of durability/maintenance advantages of WPC over traditional wood products and because of the removal of chromated copper arsenate (CCA) pressure-treated wood from the market. In order to ensure continued market share growth, WPC manufacturers need greater focus on reliability, quality, and cost. The reliability methods outlined in this paper can be used to improve the quality of WPC and lower manufacturing costs by reducing raw material inputs and minimizing WPC waste. Statistical methods are described for analyzing stiffness (tangent modulus of elasticity: MOE) and flexural strength (modulus of rupture: MOR) test results on sampled WPC panels. Descriptive statistics, graphs, and reliability plots from these test data are presented and interpreted. Sources of variability in the MOE and MOR of WPC are suggested. The methods outlined may directly benefit WPC manufacturers through a better understanding of strength and stiffness measures, which can lead to process improvements and, ultimately, a superior WPC product with improved reliability, thereby creating greater customer satisfaction.