存貨往往是企業的運作過程中不可或缺的環節。在過去的文獻中，已有許多文獻探討了在各種情形下求取最佳訂購量的存貨模型。在商品退化率的部份，過去的研究多假設商品的退化情形為一常數或隨時間遞增，但實務上的觀察可知有許多商品在儲存初期不會發生退化，而是在一段時間後，才開始產生腐壞、超過保存期限等現象，我們稱此類商品為非瞬時退化性商品。然而，關於非瞬時退化性商品的存貨模型在過去的文獻中甚少被討論，因此本研究擬以非瞬時退化性商品為對象，探討在有限的計劃週期內需求為變動且允許延遲付款的存貨模型。 在此本研究以傳統的經濟訂購量模型為基礎，透過數學模型建立企業最佳的存貨模式，並提供一演算法進行求解以找出企業最佳商品訂購策略。在研究中，首先假設上游供應商會提供一延遲付款的期限，而週期開始初期商品的退化率為零，經過固定時間過後則退化率改變為一固定常數，並以此分成三個部份探討在有限計劃週期內考慮固定、線性與指數型需求率的存貨模式，最後再佐以敏感度分析探討主要變數對模型的影響效果。 The inventory system is taking an important part of cost controlling in business operation. There are numerous literatures to discuss the issue of optimal inventory cost by using EOQ (Economic Order Quantity) model. Most of the researches assumed that the deterioration rate are fixed or slightly increased. In the real situation, many goods could be kept for a period without deterioration, but it would start to deteriorate later in a fixed duration. We named these kinds of goods as “Non-instantaneous Deteriorating Items”. Therefore, the economic order quantity models of non-instantaneous deteriorating items are still rarely, so we aimed to establish an inventory model for non-instantaneous deteriorating items over a finite time horizon. Moreover, delay in payment is allowable. In this study, we used EOQ method for finding the optimal ordering quantities, and used mathematical model for establishing business’s inventory mode. We assumed that the supplier would provide a time period of paying for business. Initializing the inventory, the goods wouldn’t deteriorate, but starting to deteriorate in a constant rate after a fixed period later. We divided this study into three parts by different demand types of constant, linear, and exponential.
