考慮產品生命週期末端之服務性零組件最佳訂貨時程之研究─以汽車產業為例

The Optimal Replenishment Schedule Model for Auto Service Parts Considering the Phase-Out Stage of Product Life Cycle

黃珮儀(Pei-Yi Huang)

指導教授 ： 蔣明晃 ； 郭瑞祥

國立臺灣大學/管理學院/商學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.00024

摘要

近年來產品生命週期各階段因時制宜的管理策略已成為企業亟需處理的問題。其中產品需求量會隨產品生命週期有極大的變動，因此因應產品生命週期的存貨管理機制變相當重要。在產品生命週期的衰退期，需求量逐漸走弱，此時存貨管理上必頇有相對應的訂貨時程時程與訂貨批量，以適時的降低存貨水準，避免發生過剩存貨，造成公司鉅額的損失。本研究的目的即為考量產品生命週期末端的需求下降趨勢，提出最佳的訂貨時程以極小化總存貨成本。本研究提出一個允許缺貨發生下的成本模型，並將存貨持有成本、缺貨成本、緊急訂單成本以及正常訂單成本納入成本模型，得出最佳的訂貨時程。並利用實際個案公司的汽車維修服務件的資料作實際數值分析，針對成本模型求解，得到最佳訂貨時程。最後再對存貨成本與需求預測模型的相關參數進行敏感度分析。分析結果顯示，當持有成本相對較高時，本模型會建議單次訂貨，並採缺貨再補的訂貨策略。此時，備貨期間長短與存貨持有成本、正常訂單成本、欠撥待補比率成負相關，與銷貨損失成本與急單成本成正比。當持有成本相對較低時，本模型會建議備足訂貨時程所需滿足的需求量作為存貨，將缺貨降至零。此時的訂貨時程與需求預測函數中的次方係數b的絕對值成正比，與存貨持有成本成反比。

關鍵字

衰退期 ； 需求下降 ； 訂貨時程

並列摘要

Recently taking a product life cycle approach toward management strategy has become a critical issue for the company. Among the management strategies regarding the product life cycle, inventory management is of great importance since the demand fluctuates significantly between different product life cycle stages, which would require different stocking policies to manage the inventory. When a product is being phased-out, the demand decreases. Therefore, the replenishment cycle and lot-size should be adjusted so as to lower the inventory level to reflect the decline in demand. The aim of this research is to propose a model to determine the optimal replenishment cycle under decreasing demand considering shortage. In the cost model, the inventory holding cost, regular order cost, lost sales cost and rush order cost are taken into account. The model is then applied to the empirical data of the automobile service parts and the optimal replenishment cycle is obtained. Further sensitivity analysis is also conducted to investigate how the cost-related and demand function-related parameters may influence the replenishment cycle. The finding showed that when the holding cost is relatively high, a single regular order will be suggested and backorder will be used. Under this scenario, the holding cost, regular order cost, backlogging ratio are negatively related to the length of period with positive inventory. Whereas,when the holding cost is relatively low, the length of period with positive inventory will equal to the replenishment cycle, which means that there is no backorder. Under this scenario, the holding cost is negatively related to replenishment cycle and the absolute value of b in the demand function is positively related to replenishment cycle.

並列關鍵字

phase out ； declining demand ； replenishment schedule

參考文獻

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