本論文的主要目的是建立一不完美維護模式，結合在虛擬年齡與利用率下之最佳維護策略，而使得總成本最小。 本論文以Liu et al. (1995)的概念為基礎，除了虛擬年齡外，系統的利用率也會影響系統的失敗率，其中利用率是一個隨機過程且具有馬可夫性質，所以是一馬可夫鏈。在此假設下，我們考慮在一有限時間內運用動態規劃法求得最佳的維護區間，並且依據不同的利用率探討維護區間的變化。The main objective of this thesis is to construct an imperfect maintenance model, which combines virtual age and utilization, for determining the optimal policy to minimize the total cost. The concept of our virtual age function is based on Liu, Makis and Jardine (1995). However, we add a variable, utilization rate here which is different from the original concept. The utilization rate is a stochastic process with Markov property, so the stochastic process is a Markov chain. The restoration degree and utilization of the system are both assumed to influence the failure intensity following a virtual age process. In this situation, we finally use dynamic programming to find the optimal overhaul intervals with finite planning horizon, and show how it varies with alternation of utilization.
