• 디지털산업정보학회논문지
• /
• 제7권2호
• /
• pp.1-8
• /
• 2011

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 finite failure non-homogeneous Poisson process models presented and the life distribution applied extreme distribution which used to find the minimum (or the maximum) of a number of samples of various distributions. 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.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 하계학술대회 논문집 D
• /
• pp.2376-2378
• /
• 2002

Redundant Programmable Logic Controllers are used in practice with the aim of achieving higher degree of availability or fault tolerance. In the paper a proposed Multiplex-PC is controled for fault tolerance design. In order to select a Different-Vender by a Supervisor computer, a Multiplex-PC is designed by TCP/IP internet protocol[1]. Because TCP/IP internet protocol can not connect to CPU. We use TCP/IP internet protocol to join CPU. We have to use TCP congestion control to select Different-Vender [4]. The reliability of the fault tolerant is measured with MTBF(Mean Time Between Failures)[3].

• 한국항공운항학회지
• /
• 제17권4호
• /
• pp.25-31
• /
• 2009

In development phase of the Aircraft Systems, the reliability prediction of electronic equipments are usually performed using MIL-HDBK-217. The reliability of fielded electronic systems, however, used to be underestimated with MIL-HDBK-217. To solve this problem, some alternatives are suggested and Telcordia SR-332 is among them. In this case study, the reliability of ESU which controls gas turbine engine is predicted using Telcordia SR-332 along with the development test data. The predicted reliabilities of ESU using Telcordia SR-332 and MIL-HDBK-217 are also compared. As a result this case study showed that the predicted reliability using Telcordia SR-332 was better close to field(operation) reliability than MIL-HDBK-217.

• Journal of Power Electronics
• /
• 제10권6호
• /
• pp.660-666
• /
• 2010

This paper presents the approach followed to develop a course that introduces reliability into the design of power electronics converters. The course is part of the curriculum of a master of science in electrical engineering program, and it is aimed at providing reliability tools that can be used in a straightforward manner, while avoiding the mathematical intricacies. The reliability calculations are performed according to the Military Handbook 217, using the evaluation version of a commercial software package which greatly reduces the computational burden usually associated with this task. The course assessment shows that, after attending the course, students were able to improve the mean time between failures in a power-electronics converter, from a minimum of 5%, up to 100%.

• 디지털산업정보학회논문지
• /
• 제8권4호
• /
• pp.25-34
• /
• 2012

In this study, in the process of testing before the release of the software products designed, software testing manager in advance should be aware of the testing-information. Therefore, the effective learning effects perspective has been studied using the NHPP software. The finite failure nonhomogeneous Poisson process models presented and applied property of learning effect based on truncated time and delayed S-shaped software reliability. 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 autonomous errors-detected factor that is generally efficient model can be confirmed. This paper, a failure data analysis was performed, using time between failures, according to the small sample and large sample sizes. The parameter estimation was carried out using maximum likelihood estimation method. Model selection was performed using the mean square error and coefficient of determination, after the data efficiency from the data through trend analysis was performed.

• 산업경영시스템학회지
• /
• 제39권4호
• /
• pp.49-59
• /
• 2016

Naval combat system developed in-country is progressing at an alarming rate since 2000. ROK navy will be achieved all vessels that have combat system in the near future. The importance of System Engineering and Integrated Logistics Support based on reliability analysis is increasing. However, reliability analysis that everyone trusted and recognized is not enough and applied practically for development of Defense Acquisition Program. In particular, Existing Reliability Analysis is focusing on reliability index (Mean Time Between Failure (MTBF) etc.) for policy decision of defense improvement project. Most of the weapon system acquisition process applying in the exponential distribution simply persist unreality due to memoryless property. Critical failures are more important than simple faults to ship's operator. There are no confirmed cases of reliability analysis involved with critical failure that naval ship scheduler and operator concerned sensitively. Therefore, this study is focusing on Mean Time To Critical Failure (MTTCF), reliability on specific time and Operational Readiness Float (ORF) requirements related to critical failure of Patrol Killer Guided missile (PKG) combat system that is beginning of naval combat system developed in-country. Methods of analysis is applied parametric and non-parametric statistical techniques. It is compared to the estimates and proposed applications. The result of study shows that parametric and non-parametric estimators should be applied differently depending on purpose of utilization based on test of normality. For the first time, this study is offering Reliability of ROK Naval combat system to stakeholders involved with defense improvement project. Decision makers of defense improvement project have to active support and effort in this area for improvement of System Engineering.

• 약학회지
• /
• 제37권4호
• /
• pp.383-388
• /
• 1993

Pharmacokinetics of aucubin, an irdoid glucoside, was compared in rats of experimental hepatic failure(EHF). EHF was induced by CCI$_{4}$ or D-galactosamine pretreatment. This work was designed to find out any differences in the pharmacokinetics of aucubin that may explain the different protective effect of aucubin on CCI$_{4}$- and galactosamine-induced EHF : aucubin reportedly protected CCI$_{4}$-inducing hepatotoxicity effectively, but did not for galactosamine-hepatotoxicity. EHF was induced by intraperitoneal injection Of CCI$_{4}$(0.9ml/kg) or galactosamine(250 mg/kg) to Wistar rats 24 hr before the pharmacokinetic study. The rats were fasted during the 24 hr. Aucubin was iv injected at a dose of 15 mg/kg and the plasma aucubin was assayed by HPLC. There were no significant differences in the pathophysiologies(body weight, liver weight, GTP, hematocrit, blood cell distrbution and plasma protein binding of aucubin) between the two EHF models except GOP which was significantly (p<0.05) higher in CCI$_{4}$-than in galactosamine-EHF. On the other hand, pharmacokinetics of aucubin such as total cleatance(CL$_{t}$), distribution volume at steady-state(Vd$_{ss}$), and mean residence time(MRT) differed significantly(p<0.05) between the models : for example, CL$_{t}$ was increased two fold by CCI$_{4}$, but not by galaclosamine ; Vd$_{ss}$, in galactosamine-EHF was higher than that in CCI$_{4}$-EHF ; MRT was decreased by CCI$_{4}$, but increased conversely by galactosamine. The increase of CL$_{t}$(and decrease of MRT) in rats of CCI$_{4}$-EHF was contrary to the general expectation for the hepatic failure : most of the hepatic failures have been known to decrease CL$_{t}$ of the administered drugs. Whether the difference in the pharmacokinetics is responsible for the different protective effect of aucubin against the two EHF models is of interest. However, much more studies on biliary excretion, urinary excretion, and hepatic uptake in cellular level should be preceded before any conclusions are made on the role of different pharmacokinetics on the different pharmacology of aucubin.

• 품질경영학회지
• /
• 제40권3호
• /
• pp.278-285
• /
• 2012

Purpose: Weapon systems have the long life cycle unlike the consumer product. Thus, the reliability of weapon system is improved during the life cycle through the steady technical change. In this paper, we deal with the method of evaluating the reliability of weapon system with the field failure data. Methods: Especially, we present how to gather the field failure data and evaluate the reliability through the case of K-series weapon system. To evaluate reliability, the reliability growth model is used and the result is discussed. Results: It is steadily improved the reliability of K-series weapon system deployed from 2000 to 2004. The frequency of the failures that affect the mission is largely reduced and MTBMF(mean time between mission failure) is also improved. Conclusion: We can guess the trend of the reliability of weapon system with the field data through this study. Furthermore, it can be used to improve the reliability and make maintenance policy.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2010년도 제35회 추계학술대회논문집
• /
• pp.143-148
• /
• 2010

항공용 연료계통의 핵심부품인 연료승압펌프(FBP)의 신뢰도를 예측/평가하기 위하여 운용중에 지속적으로 발생되는 고장자료에 근거하여 고장추세분포를 도출하는데 Weibul Distribution 형태의 통계학적인 방법(Statistical Methods)을 사용하였다. 이를 토대로 하여 고장 자료분포를 시각적으로 분석하여 신뢰성 예측을 하였다. 분석결과, 형상모수(${\beta}$), 척도모수(${\eta}$) 및 평균고장시간(MTTF)을 산출하였다. 결과로부터 주요 고장원인이 기계부품의 마모나 노후화로 인하여 발생하는 마모고장기이며 산출된 평균고장시간 이전에 예방정비를 수행해야 사전에 고장을 방지할 수 있음을 알 수 있다.

• 한국산학기술학회논문지
• /
• 제12권10호
• /
• pp.4543-4549
• /
• 2011

본 연구에서는 소프트웨어 제품을 개발하여 테스팅을 하는 과정에서 소프트웨어 관리자들이 소프트웨어 및 검사 도구에 효율적인 학습기법을 이용한 NHPP 소프트웨어 모형에 대하여 연구 하였다. 적용분포는 버르 분포를 적용한 유한고장 NHPP에 기초하였다. 소프트웨어 오류 탐색 기법은 사전에 알지 못하지만 자동적으로 발견되는 에러를 고려한 영향요인과 사전 경험에 의하여 세밀하게 에러를 발견하기 위하여 테스팅 관리자가 설정해놓은 요인인 학습효과의 특성에 대한 문제를 비교 제시 하였다. 그 결과 학습요인이 자동 에러 탐색요인보다 큰 경우가 대체적으로 효율적인 모형임을 확인 할 수 있었다. 본 논문의 수치적인 예에서는 고장 간격 시간 자료를 적용하고 모수추정 방법은 최우추정법을 이용하여 추세분석을 통하여 자료의 효율성을 입증한 후 평균자승오차와 $R^2$(결정계수)를 이용하여 효율적인 모형을 선택 비교하였다.