對於大部分的製造業而言，批量生產模式最被為廣泛使用，因此存貨管理一直是相當重要的議題。在許多生產存貨模式的文獻中已探討各種狀況的傳統經濟生產批量（Economic Production Quantity，EPQ）問題，並且也有很多研究改變或放寬傳統EPQ模式的基本假設條件，使得模式更符合實際生產狀態。但是隨著社會環境與全球經濟型態的變化，總成本結構與以往的生產條件大不相同，並且在消費者對於產品品質日益要求嚴格的情形下，以及生產機台設備的改良進步，在考量總成本最小的同時，也需將產品檢驗、設備之預防保養以及不良品與企業相關成本列入考量，以冀有一個更符合實務的經濟生產批量策略。 在不完美製程中，製程服從具有遞增危險率的一般退化分配，在這樣的退化性生產系統中，預防維護(preventive maintenance，PM)活動通常是不完美的，生產系統在實施PM之後將不會像新的一樣好，但會依據PM水準而成一定比例的減少系統的年齡。本研究乃在不完美製程(Imperfect Process)與不完美維護(Imperfect maintenance)之情形下，對於訂定經濟生產批量與最佳維護策略，分別探討三種生產條件對於生產總成本的影響。第一種模式為考慮製程進行小修與考慮檢驗時間，第二種模式為第一種模式之推廣為考慮檢驗誤差、保養誤差與製程小修，並各發展出一個整合模式。最後亦利用模型的建立以韋伯衝擊模式（Weibull shock model）為例進行數值分析，在期望總成本最小化的目標下，解析在不同參數下的最佳經濟生產批量，並提出最佳的檢驗與預防維護策略，且證明執行預防維護會使得總成本減少，以及預防維護的程度也會影響最佳解。 第三種模式則是對於不完美製程考慮不良品可以進行不完美重工製程與允許缺貨存在條件下，發展出一個整合模型。在不完美重工製程中，有一定比例的不良品可以經由重新加工成為良品，另一部份則會成為報廢品。最後亦使用數值分析來模擬不同參數改變對於最佳解的影響，以及在最大總利潤的目標下提出最佳檢驗區間、檢驗次數，與生產批量，並且探討重工製程的利益。 Most manufacturing industries utilize the batch model of production. Therefore, determining the optimal economic production quantity (EPQ) is a relevant inventory management issue. Determining EPQ for manufacturing processes has been extensively studied in the literature. However, changes in the social environment and global economy have affected the total cost structure. Consumers are more concerned than before about product quality and manufacturing equipments has improved. While thinking about minimal total cost, other important considerations are product inspection, maintenance of equipments, non-conforming products and related costs of implementing EPQ strategy for more practical situations. The imperfect process has a general deterioration distribution with increasing hazard rate. Even with periodic preventive maintenance, such a production system can not be recovered as good as new. This means that the system condition depends on how long it runs. Also, the PM level can be distinct due to the maintenance cost. This research develops integrated models and explores the influence on the total production cost of three production conditions in considering the situations of an imperfect process with imperfect maintenance for the joint determination of economic production quantity (EPQ), inspection and preventive maintenance. The first takes minimal repair and inspection time into consideration to develop an integrated model. The second extends the first model to consider inspection errors and preventive maintenance error due to human or technological limitations. And implementing the model to use Weibull shock model as an example conducts numerical analysis. In the goal of minimal expected total cost, this research analyzes the optimal EPQ in various conditions to propose the optimal strategy of inspection and PM, and to prove that performing PM makes the reduction of total cost. The third develops an integrated model in considering the situations of an imperfect process with shortage, and an imperfect rework process for non-conforming items. There is a percentage of the reworking items fail the repairing and become scrap items in the imperfect rework process. We use numerical analyses to simulate the effect of changes in the various parameters on the optimal solution. And look at the optimal inspection interval, inspection frequency and production quantity that maximum total profit which the advantages of rework process were explored.
