• Journal of Korea Multimedia Society
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• v.16 no.3
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• pp.336-341
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• 2013

Reliability analysis for various forms of data obtained from complicated electronic circuits is a necessary process for guaranteeing reliability of the system. Reliability assessment of a system starts from the estimation of failure function. A system can be composed of one item, but in most cases, several items are correlated to each other in one system. This study suggests an estimation method of failure function and reliabilities for infrequent failure events, by considering different form of data obtained from different systems. Estimates of failure function and reliabilities for complex systems composed of two or more items in parallel or in mixed connections can be done by further application of proposed method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1346-1352
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• 2009

Warranty cost of automobile parts varies depending on the parts failure rate in a warranty region of individual markets. Parts failure rate is significantly affected by usage-rate given that other stressors of individual markets are similar. Accordingly, warranty cost can be predicted by failure modeling which reflects usage-rate and using a stochastic process. In this paper, one-dimensional approach is used by applying accelerated failure time model on the assumption that the usage-rate is linear. Such model can explain changes in parts failure rate depending on the changes in usage-rate since it can be expressed as a function of usage-rate. Therefore, acquisition of usage-rate in a new market will automatically lead to estimate of failure rate even without warranty data and warranty cost of parts can be predicted through a renewal process in replacement cases. A case study using warranty data of two real markets is presented in the application part of this paper.

• Proceedings of the KWS Conference
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• 1997.10a
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• pp.59-63
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• 1997

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.5
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• pp.496-502
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• 2016

In this study, we investigated the comparative NHPP software model based on learning techniques that operators in the process of software testing and development of software products that can be applied to software test tool. The life distribution was applied Makeham distribution based on finite fault NHPP. Software error detection techniques known in advance, but influencing factors for considering the errors found automatically and learning factors, by prior experience, to find precisely the error factor setting up the testing manager are presented comparing the problem. As a result, the learning factor is larger than automatic error that is usually well-organized model could be established. This paper, a trust characterization of applying using time among failures and parameter approximation using maximum likelihood estimation, after the effectiveness of the data through trend examination model selection were well-organized using the mean square error and $R^2$. From this paper, the software operators must be considered life distribution by the basic knowledge of the software to confirm failure modes which may be helped.

• Convergence Security Journal
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• v.13 no.1
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• pp.71-78
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• 2013

In this study, software products developed in the course of testing, software managers in the process of testing software test and test tools for effective learning effects perspective has been studied using the NHPP software. The doubly bounded power law distribution model makeup Weibull distribution applied to distribution was based on finite failure NHPP. Software error detection techniques known in advance, but influencing factors for considering the errors found automatically and learning factors, by prior experience, to find precisely the error factor setting up the testing manager are presented comparing the problem. As a result, the learning factor is greater than automatic error that is generally efficient model could be confirmed. This paper, a numerical example of applying using time between failures and parameter estimation using maximum likelihood estimation method, after the efficiency of the data through trend analysis model selection were efficient using the mean square error and $R^2$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5D
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• pp.497-504
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• 2010

In this paper, the author presents a reliability estimation technique to analyze the effects of traffic loads on pavement mean life based on the national highway database of Suwon and Uijeongbu region from 1999 to 2008. The estimation of the mean life, its standard deviation and reliability for pavement sections are calculated by using an appropriate distribution, Lognormal distribution, based on reliability theory. Furthermore, the probability paper method and Maximum likelihood estimation are both used to estimate parameters. The author found that mean life of newly constructed sections and over-layed sections is about 6.5 to 7.9 years and 7.3 to 9.1 years, respectively. The author also ascertained that the results of cumulative failure probability for pavement life between the proposed methods and observed data are similar. Such an assessment methodology and measures based on reliability theory can provide useful information for maintenance plans in pavement management systems as long as additional life data on pavement sections are accumulated.

• 한국항공운항학회:학술대회논문집
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• 2015.11a
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• pp.224-230
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• 2015

항공기 엔진 체계의 신뢰성과 안전성을 분석하는 것은 RAM 분석이라고 한다. RAM은 제작자가 개발한 시스템의 지속가능성 혹은 그 체계의 수명주기비용(Lice Cycle Cost)에 중대한 영향을 줄 수 있는 시스템 설계특성을 의미한다. 또한 RAM은 시스템이 개발될 당시에 의도된 임무를 수행할 수 있는 능력 혹은 임수수행을 성공할 수 있도록 담보하는 중요한 역할을 한다. RAM은 1970년대 이후 미국 군수분야에서는 군수지원성분석(LSA, Logistic Support Analysis) 과 밀접히 연계되어 활용되어 왔으며, RAM과 LSA를 통합하여 종합군수지원체계(ILS, Integrated Logistics Support)라고 부른다. 본 연구에서는 항공기 엔진에 대한 신뢰성 분석에 Weibull 분포를 활용하였다. Weibull 분포는 2개의 변수 적용에서 다음과 같이 정의된다. 변수가 그 계의 어떤 값을 나타내느냐에 따라 분포도 곡선의 특성 의미는 변수에 의존된다. 예를 들어 시험성적, 사회적 특성을 표현하는 인지도, 산업 제품의 고장이나 결함을 나타내는 고장관련 모수(변수) 등에 따라 그 특징을 나타내게 된다. 항공기 엔진의 신뢰성 분석을 통해 항공기 엔진의 수명 판단이 가능해졌으며 임무 불가능 수준의 In-Flight Shut-Down 비율이 현격히 감소됨을 확인할 수 있었다.

• Journal of the Korean Data and Information Science Society
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• v.24 no.4
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• pp.755-762
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• 2013

In this paper we consider the NHPP software reliability model. And we deal with the maximum likelihood estimation and the Bayesian estimation with conjugate prior for parameter inference in the mean value function of Goel-Okumoto model (1979). The parameter estimates for the proposed model is presented by MLE and Bayes estimator in data set. We compare the predicted number of faults with the actual data set using the proposed mean value function.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.33-41
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• 2012

The aim of the study is to investigate the method to estimate a shelf life of KM6 single base propellant by stochastic gamma process model. The state failure level is assumed that the degradation content of stabilizer is below 0.8%. The constant of time dependent shape function and the scale parameter of stationary gamma process are estimated by moment method. The state distribution at each storage time can be shown from probability density function of deterioration. It is estimated that the $B_{10}$ life, a time at which the cumulative failure probability is 10%, is 25 years and the $B_{50}$ life is 36 years from cumulative failure distribution function curve. The $B_{50}$ life can be treated as the average shelf life from the practical viewpoint and the lifetime can be expressed as distribution curve by using stochastic process theory.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.935-944
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• 2023

In this study, the Inverse-type (: Inverse-Exponential, Inverse-Rayleigh) life distribution, which is known to be suitable for reliability research, was applied to a software development cost model based on finite failure NHPP(: Nonhomogeneous Poisson Process), and then the attributes that determine the model's performance were analyzed. Additionally, to evaluate the efficiency of the model, it was compared with the Goel-Okumoto basic model. The performance of the model was analyzed using failure time data, and MLE (: Maximum Likelihood Estimation) was applied to calculate the parameters. In conclusion, first, as a result of analyzing m(t), which determines the development cost, the Inverse-Exponential model was efficient due to its small error in the true value. Second, as a result of analyzing the release time along with the development cost, the Inverse-Rayleigh model was confirmed to be the best. Third, as a result of comprehensive evaluation of the attributes (m(t), cost, and release time) of the proposed model, the Inverse-Rayleigh model had the best performance. Therefore, if software developers can effectively utilize this research data in the early process, they will be able to proactively explore and analyze attributes that affect cost.