| Summary: | 碩士 === 華梵大學 === 工業管理學系碩士班 === 89 === To face the improvement of the technology, the equipment of the system is getting more and more complicated and larger. Once the failure occurs, it will cause serious damage and harm. So the reliability and maintainability have significant impact on the process of product design. High reliability of the product is an emblem of the warranty of quality. High maintainability is a good tool to maintain the life of the system So the optimum replacement policy plays an important role.
In this thesis, a system is replaced by an opportunity-based age or number of minimal repairs. The system has two types is of failures, which are type I failures (minor failures) and type II failures (catastrophic failures). In generally, the time which system is replaced at first type II failure or the opportunity after age or minimal repair, whichever occurs first. Type I and type II failures are age-dependent. Type I failures be recondition by minimal repairs, whereas type II failures are removed by replacements. The opportunity arises according to a Poisson process, which is independent of failures of the component. The primary aim of this thesis is to derive the expected log-run average cost per unit time. The optimal critical time and the optimal repair time which would be found in some conditions. Various special cases are considered. Finally, a numerical example is given.
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