在租賃觀念興起的時代中，愈來愈多提供租賃服務的出租商產生，出租商將設備交付於客戶後，設備處於各個具有高度變異的環境中，可能會遭遇許多不可預期的意外，使得設備加速退化。當設備頻繁失效時，將導致高昂維修與賠付成本，為了改善設備失效次數，考慮加入保養活動是不錯的辦法。一般而言，設備的保養成本往往低於維修成本，但頻繁地保養將造成資源浪費，過去學者在制定保養政策時，多以固定週期、固定水準的角度進行探討。
本研究以一般退化程度、衝擊傷害規模兩類失效因素，並加總兩者退化程度作為總退化程度，建立出相依多重競爭失效因素下之可靠度模式，描述設備受到的加速退化現象。當考量較多失效因素時，保養政策必須更具彈性，透過非週期性的保養區間、可變動之保養水準訂定策略。以受到合約規範、負責保養與維修的出租商角度建立成本模式，其中包含修復成本、違約成本與保養成本，進行有、無保養兩政策的總成本比較。
本研究提出一套啟發式演算法，在特定區間進行試誤法，將局部最佳解的時間點作為新的求解區間，透過最小化總成本的條件，求得最佳保養時間點與水準組合。結果發現，有保養政策之成本皆優於不保養，其中又以非週期性保養較佳，在非週期性保養中，可再細分為固定水準與變動水準兩政策。透過參數分析，發現當單位超時成本小於500或災難性失效門檻值小於1.75時，採取變動水準較佳，反之則採取固定水準；影響總成本的關鍵則在於單位超時成本、災難性失效門檻值、韋伯函數之尺度係數與串聯元件數。

The purpose of this thesis is to obtain an effective and flexible preventive maintenance (PM) policy from the perspective of lessors. Research on PM mostly assumed that the interval between two PMs are the same (periodic preventive maintenance, P-PM) and the maintenance level of each PM is fixed. This study developed a reliability model with non-periodic PM policy (NP-PM) for leasing equipment that consists of series-parallel components with multiple dependent competing failure processes (MDCFP). We assume the occurrence frequency of random shocks is independent of the degree of general degeneration, but the degree of total degeneration is dependent on general degeneration and random shock damages. Each interval between two PMs and the maintenance level are changeable. The cost structure incorporated maintenance cost, minimal repair cost and the penalty cost for breach of contract. This thesis developed a heuristic algorithm to obtain the execution time and the maintenance level of each PM. A numerical analysis is performed by using the data of a micro-electro-mechanical system. The results reveal that NP-PM policy is better than P-PM policy.

中文部分：
施博穎 (2014)，「具相依多重競爭失效過程系統之最佳化設計與保固期內之預防保養策略」，國立成功大學工業與資訊管理學系碩士論文。
李秉鍵 (2016)，「相依多重競爭失效模式之維護成本分析」，國立成功大學工業與資訊管理學系碩士論文。
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