基於顧客最低需求承諾之存貨模式

Abstract

電子相關產品變化快速，顧客需求不確定，企業面臨該備多少料的問題。若備料不足，無法滿足客戶需求，可能導致客戶流失；反之，若備太多料，在價格快速下跌的環境下，可能導致極高的存貨成本。 本論文假設製造商的生產數量受限於關鍵零組件的採購量，組裝產能無限，客戶期末需求為已知的機率分配，其參數由客戶期初的承諾購買量決定，製造商期初向上游供應商訂貨Q個關鍵零組件。期末客戶確定實際需求時，若備料不足，製造商需以較高的價格緊急訂貨，緊急訂貨量受限於期初採購量。本論文的利潤函數包含兩種缺貨成本及存貨成本。缺貨分為低於承諾量的缺貨、及高於承諾量但低於實際需求的缺貨兩種；存貨分為低於承諾量的存貨，及高於承諾量的兩種不同的存貨成本。 本論文構建數學模式，以最佳的期望利潤最大化為目標，利潤函數包含收益及成本，成本函數包含產品的生產成本、期末存貨和缺貨成本，本論文提出求最佳採購量的解法，並探討各參數對期望利潤的影響。

Rapidly changes in the marketplace of electronic products are forcing manufacturers emphasizing their inventory policies for decreasing inventory costs to enhancing competitiveness. In this study, we investigate a customer’s minimum-commitment contract in which customer provides a minimum-commitment order quantity for a particular key component at the beginning of period. Customer’s real demand is uncertainty. Because of the presence of a lead time, manufacturer should make a decision to determine an initial ordering quantity for the key component at the beginning of the period. A rush order, with a higher unit cost and having upper quantities bound, is permitted at the end of the period. In this study, we assume that the producing quantities are determined by the available quantities of the key component. Due to the limitation of rush order quantity, two types of shortage cost /holding cost are considered in this study. One type of shortage /holding cost is that the available quantity of the particular key component is less than the minimum-commitments and also less/more than real demand, the others is that the available quantity is more than the minimum-commitments and also less /more than real demand. Unit shortage cost of the former is higher than that of the latter. On the contrary, Unit holding cost of the former is less than that of the latter. Consider above-mentioned two types of shortage and holding costs, a profit model for manufacturer is formulated to determine the initial ordering quantity. We prove that the profit function is a concave function and we also provide a solution procedure. Finally, examples are given to illustrate the solution procedure.