臺灣博碩士論文加值系統

在以往學者所討論的存貨模式文獻中，不論是在確定性模式（deter-ministic model）或機率性的模式（probabilistic model）中，多半都將前置時間視為已知且不可控制的常數（uncontrollable constant）或隨機變數。但是近年來，有不少學者開始對於前置時間是否真的為不可控制的常數或隨機變數的問題產生了些許的質疑，進而著手進行了在連續性檢查訂購策略下之可控制前置時間的相關研究。在此檢查策略之下，許多的學者已進一步去探討前置時間與訂購量間的互動關係。但是以往的文獻中，雖然已考慮到前置時間的控制，但往往都忽略了請購點對於存貨全年總成本的影響，這樣的訂購策略在實務上是來說是很不切實際的。所以，在本文中，我們試著去將請購點視為決策變數。而一般實務上，在前置時間內，不同的顧客在其需求上亦會有所差異，所以不能單單用一個需求分配來滿足顧客在前置時間內的需求。因此，在本文中我們考慮用一混合分配來描述前置時間的需求量。
Ouyang和Wu（1997）更進一步以服務水準替代目標函數中的缺貨項目，建構了前置時間內需求量之機率分配為常態與未知的兩種存貨模式。但是他們仍舊沒有將請購點視為決策變數。而在關於交貨的貨品中存在有瑕疵品（defective items）的存貨模式方面，Silver（1976）曾提出一個到達批貨量中，所存在的瑕疵品個數為一隨機變數，且服從已知的機率分配的存貨模式。Kalro和Gohil（1982）推廣了Silver（1976）的模式，考慮缺貨期間數量允許完全或部分欠撥（completely or partially backordered）的情形。前面這些討論有關瑕疵率的研究文獻中，都假設前置時間為固定常數且為不可控制的。在吳坤山（1997）與莊博仁（1999）之博士論文中，在連續性檢查的策略下對於瑕疵品項與服務水準的限制方面，皆在前置時間內需求量之機率分配為常態和未知的情況下加以探討，並將連續性檢查改為週期性檢查。
本文第二章我們推廣Ouyang和Wu（1997）和Wu與Tsai（2001）的模式，在服務水準的限制下，考慮以混合分配F*=pF1+(1-p)F2，來滿足前置時間顧客的需求量，並各自在請購點為固定值與請購點為決策變數時加以討論。第三章我們推廣Ouyang和Wu（1999）的模式，在到達的批貨量中，含有瑕疵品的項目，同於前一章，我們亦考慮了混合常態與混合分配未知的情況，並進一步去討論比較請購點為固定值與請購點為決策變數時討論。最後，第四章為結論，對本文各章所建構的存貨模式做個歸納總整理，同時提出未來的研究方向。

In most of the literatures dealing with inventory problems, either in deterministic model or probabilistic model, lead time is usually viewed as a prescribed constant or a stochastic variable, which therefore, is not subject to control. But recently, many authors started to present their studies about a continuous review model in which they consider the controllable lead time. Besides, many authors discussed the relationship between the lead time and the order quantity. But they always ignored the reorder point. This kind of order policy is not reasonable. So, in this article we try to consider the reorder point as a decision variable. And in many practical situations, we can not use only a single distribution to describe the customers’ demands of the lead time. So, we consider to use a mixtures of distribution to describe the demand of the lead time.
Recently, Ouyang and Wu(1997) use a service level constraint to replace the stockout cost term in the objective function, and consider the distribution of the lead time demand which is normal and free. But they still do not consider the reorder point as a decision variable. Making mention of the inventory model about the defective items, Silver(1976) presented a model which the defective rate is a stochastic variable. Wu(1997) and Chuang(1999) presented continuous review models, with defective items and a service level constraint, which the distribution of the lead time demand is normal and free.
In Chapter 2, we extend the model of Ouyang and Wu(1997) and Wu and Tsai(2001), and consider a service level constraint. Then we use the mixtures of distribution F*=pF1+(1-p)F2 to describe the demand of the lead time and discuss the situations when both the reorder point is fixed and the reorder point is viewed as a decision variable. In Chapter 3, we extend the model of Ouyang and Wu(1999) to consider the number of defective units in an arrival order. Then we use the mixtures of distribution to describe the demand of the lead time and discuss the situations when both the reorder point is fixed and the reorder point is viewed as a decision variable. Finally, the conclusion of the above chapter 2 and 3 and the future research are also given in chapter 4.

表目錄 ……………………………………………………………………III
第一章 緒論 …………………………………………………………………1
1-1 研究動機與目的………………………………………………………1
1-2 文獻探討………………………………………………………………3
1-3 研究架構………………………………………………………………5
第二章 隨機變數前置時間服從混合型分配在服務水準限制下
的混合存貨模式…………………………………………………… 6
2-1符號說明與假設……………………………………………………… 6
2-2前置時間需求量服從混合型常態分配之存貨模式………………… 9
2-2-1決策變數為訂購量與前置時間之存貨模式………………… 9
2-2-2決策變數為訂購量，前置時間與請購點之存貨模式……… 16
2-2-3數值範例……………………………………………………… 21
2-3前置時間需求量服從的分配未知之存貨模式………………………22
2-3-1決策變數為訂購量與前置時間之存貨模式………………… 23
2-3-2決策變數為訂購量，前置時間與請購點之存貨模式……… 28
2-3-3數值範例……………………………………………………… 34
2-4敏感性分析……………………………………………………………35
第三章 隨機變數前置時間服從混合型分配且貨物中含有瑕疵品
的混合存貨模式……………………………………………………39
3-1符號說明與假設………………………………………………………39
3-2前置時間需求量服從混合型常態分配之存貨模式…………………40
3-2-1決策變數為訂購量與前置時間之存貨模式………………… 41
3-2-2決策變數為訂購量，前置時間與請購點之存貨模………… 46
3-2-3數值範例……………………………………………………… 50
3-3前置時間需求量服從的分配未知之存貨模式…………………… 51
3-3-1決策變數為訂購量與前置時間之存貨模式………………… 51
3-3-2決策變數為訂購量，前置時間與請購點之存貨模式……… 55
3-3-3數值範例……………………………………………………… 60
3-4敏感性分析……………………………………………………………61
第四章 結論…………………………………………………………………66
參考文獻…………………………………………………………………… 72
附錄：……………………………………………………………………… 76
表目錄
表4-1.在服務水準受限制與需求為單峰分配下，參數變動與
成本間的互動關係………………………………………………… 68
表4-2.在服務水準受限制與需求為雙峰分配下，參數變動與
成本間的互動關係………………………………………………… 68
表4-3.在批貨量中含有瑕疵品與需求為單峰分配下，參數變動與
成本間的互動關係………………………………………………… 70
表4-4.在批貨量中含有瑕疵品與需求為雙峰分配下，參數變動與
成本間的互動關係………………………………………………… 71

中文部份
1.吳坤山，1997，「可控制前置時間的欠撥與銷售損失混合存貨模型之
研究」，淡江大學管理科學學系博士班博士論文。
2.莊博仁，1999，「可控制前置時間的一些隨機性存貨模型之研究」，
淡江大學管理科學學系博士班博士論文。
3.蔡慧瑩，2000，「可控制前置時間的混合型常態分配需求量之混合存
貨模式」，淡江大學統計學系應用統計學碩士班碩
士論文。
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