損耗性商品考慮貨幣時間價值及保固策略的整合性生產存貨模式

Integrated Production-Inventory Models for Deteriorating Item Taking Account of Time Value of Money and Warranty Policy

羅時添(Shyr-Tian Luo)

指導教授 ： 黃惠民

中原大學/工學院/工業工程研究所/博士(2006年)

https://doi.org/10.6840/cycu200500823

摘要

近年來，損耗性產品的存貨模式逐漸受到關注，在以往的研究中均假設損耗率為固定，但是現實環境中，以韋伯分配所描述的損耗特性，其適用範圍更為廣泛也更為接近真實狀況。以往的存貨模式均不考慮貨幣時間價值的效益，但在開發中的國家，因為其通貨膨脹率逐年增漸，造成其財務與經濟狀況更加不穩定，因此必須在存貨模式中考慮貨幣時間價值的衝擊與影響。而在日益競爭的全球環境中，與上中下游形成策略聯盟以獲取最大的利益是必然的趨勢，也因此企業間往往以結盟的方式形成供應鏈，企業間的合作與協調將使整個供應鏈系統更具效率。在即時生產系統中，以多批量運送能降低物品庫存的時間，進而降低成本。
企業在有限的資源限制下，多採取雙倉庫存貨系統以解決空間不足的窘境；為了降低成本，有些企業會嘗試將活體存貨加以培育及改良；而在真實的生產過程中，難免會產生一些不良品，因此必須將不良品加以篩選或重製；無論是良品或不良品，在出售後仍可能發生損毀的狀況，為提升顧客服務水準與滿意程度，產品售出須搭配保固策略，如此才能在消費者意識提高及競爭的環境中，佔取優勢的地位。
本論文在考慮變動損耗率、貨幣時間價值、多批量運送、整合性及允許部分缺貨的條件下，首先發展出雙倉庫的存貨系統；之後考慮不完美品質及品管檢驗下的存貨模式，其後的存貨模式並考慮將活體存貨加以培育及改良；之後考慮不完美生產程序下之存貨模式；最後再考慮提供顧客保固策略下之模式。本論文模式均以單位總成本現值最小化為目標函數，利用現金流量折現、最佳化理論及電腦應用軟體，推導出最佳的生產及補貨策略，各模式並以數值範例及敏感度分析作為驗證。

關鍵字

不完美 ； 改良 ； 雙倉庫 ； 整合性 ； 多批量運送 ； 貨幣時間價值 ； 損耗性 ； 保固策略 ； 韋伯分配

並列摘要

In recent years, the problem of deteriorating inventory has received considerable attention. In real-life situation, the Weibull distribution is more suitable to represent the distribution of the time to deterioration. Due to high inflation, the financial situation has changed in many developing countries, so it is necessary to consider the effects of the time value of money on the inventory models. With increasing global competition, it is a trend for firms to form strategic alliances with their partners in order to gain advantages. With growing focus on supply chain management, firms realize that inventories across the entire supply chain can be more efficiently managed through great cooperation and better coordination. In just-in-time production system, multiple-delivery is one way to reduce the inventory level and the total cost.
When the enterprises have limited storage capacity, they adopt the two-warehouse system to store the excess stocks. To decrease the cost, some enterprises adopt the amelioration action for the livestock. Product quality is not always perfect and actually depends on the state of the produce process. The process may deteriorate and produce some defective items. It is necessary to rework and take the screening process. Along with the highly increasing of consumer consciousness, the enterprises often offer a warranty policy as a promotional tool to rectify all failures occurring during the warranty period.
This thesis is based on the assumptions of Weibull distribution deterioration, time value of money, multiple deliveries, integration and partial backordering. We developed the two-warehouse inventory system at first. Then, we focused on the imperfect quantity and the screening process to develop an inventory model. We also considered the model for the ameliorating item. Later, we considered the imperfect production processes and rework in the inventory model. At last, we modified the previous model and considered the free-repair warranty policy in our model. This thesis developed the integrated models in order to minimize the present worth total cost per unit time. It applied the discounted cash flow (DCF), the optimization technique and computer code to derive the optimal policies. Numerical examples including the sensitivity analysis are presented to validate the results of the models.

並列關鍵字

Imperfect ； Integration ； Multiple deliveries ； Two-warehouse ； Amelioration ； Time value of money ； Warranty policy ； Weibull distribution ； Deterioration

參考文獻

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