在現實生活中，賣方通常會允許買方延遲付款。在允許延遲付款時間之內，買方不需支付尚未支付的貨款所產生的利息。因此，買方可以在延遲付款時間之內賺取販賣利潤滋生的利息，可是相對地在同時間下，賣方損失了他原本可以收到貨款所滋生的利息。然而，在允許延遲付款時間到期之後，買方還未清償完所積欠的貨款時，賣方就要向買方收取貨款中尚未付清的金額的利息。允許延遲付款策略對於賣方有兩個好處：(1)吸引到認為這項策略可以幫助削減存貨成本的新買方；(2)這項策略並不是利用降低價格的手法來吸引買方，因此較不會掀起各業者之間的削價競爭。相反的，允許信用交易的策略不僅會增加賣方額外的機會成本，也會增加賣方的違約風險。而本研究所設計的存貨模式均在信用交易之條件下所建構而成。

    在本研究中，我們建立了三個存貨模式。在第二章中，我們首先探討在信用交易同時影響需求與違約風險下找出最佳的信用交易期間與訂購量之存貨模式。與之前文獻不同之處在於，到目前為止，大部分的存貨模式的研究對象都是以買方為出發點，然而在現實生活中信用交易期間的長短是由賣方所操控的。而到目前為止只有少數研究者去探討如何幫賣方決定最佳的信用交易時間長短。故本章為賣方設計出一個經濟訂購量模式，在設計這個模式中我們融入了以下的觀念，那就是：信用交易期間的長短對於顧客的貨物需求量有正面的影響；但是對於違約風險有著負面的影響。然後在必要且充分的條件之下去導出賣方的最佳信用交易期間與訂購量。

    另外，Huang(2010)提出一個整合存貨模式，在此模式中供應商決定本身生產批量的多寡；而零售商決定本身的支出。然後再將兩者的成本結合成年度整合總支出函數，並將年度整合總支出最小化。而在第三章中，我們擴展了Huang(2010)所提的整合存貨模式，以反應下列四個事實。(1) 零售商將銷售收入存入銀行的計息帳戶中，(2)零售商所賺取的利息並不總是少於或等於其所支付的利息，(3)對於供應商而言在一次批量中的貨物運送次數多寡是其成本支出函數中的一個決策變數，(4)有必要設計一個判別式來決定零售商的補貨週期是否小於其從供應商那獲得的延遲付款期限。然後我們導出必要且充分條件以獲得最佳解，同時建立一些理論結果。

    最後，第四章中，我們提出了退化性貨品有其產品壽命的最大期限的概念，建立了一個退化性存貨模式，希望在有最大壽命期限的退化性貨品的供應鏈下為賣方訂定最佳信用交易期限與補貨週期。同時，我們也運用了以下的觀念來建構此模式，這些觀念如下：(1) 一個退化性產品的品質不僅會隨著時間不斷地衰退，且其有其產品壽命的最大期限。(2) 解在各種條件下存在的充分且必要的條件將被討論，然後一些有用的定理因此被建立。而我們還更進一步地討論非退化性貨品以作為特例。

    此外，對於以上各章之存貨模式的求解過程與理論結果，我們均有以數值範例來說明，並提供一些管理上的見解。

In practice, vendors usually offer their buyers a permissible delay in payments. During the permissible delay period, there is no interest charge. Hence, buyers can earn the interest from sales revenue meanwhile vendors lose the interest earned during the same period. However, if the payment is not paid in full by the end of the permissible delay period, then vendors charge buyers an interest on the unpaid amount of the purchasing cost. The permissible delay in payments produces two benefits to the vendor: (1) it attracts new buyers who consider it to be a type of inventory cost reduction, and (2) it is an alternative to price competition because it does not provoke competitors to reduce their prices and thus introduce lasting price reductions. On the other hand, the policy of granting trade credit financing adds not only an additional opportunity cost but also an additional dimension of default risk to the vendor.

     In this study, three inventory models have been formulated. In chapter 2, we first presented the model for the seller to find the optimal trade credit period and order quantity when trade credit impacts on both demand and default risks. Most inventory models are studied only from the perspective of the buyer whereas in practice the length of the credit period is set by the seller. So far, how to determine the optimal length of the credit period for the seller has received a very little attention by the researchers. In this chapter, we propose an economic order quantity (EOQ) model for a seller by incorporating the relevant fact that trade credit has a positive impact on demand but a negative impact on default risks. Then the necessary and sufficient conditions to obtain the seller’s optimal trade credit period and order quantity are derived.

     Next, Huang (2010) proposed an integrated inventory model with trade credit financing in which the vendor decides its production lot size while the buyer determines its expenditure to minimize the annual integrated total cost for both the vendor and the buyer. In chapter 2, we extend his integrated supply chain model to reflect the following four facts: (1) generated sales revenue is deposited in an interest-bearingaccount for the buyer, (2) the buyer’s interest earned is not always less than or equal to its interest charged, (3) the total number of shipments in one lot size is the vendor’s decision variable to minimize the cost, and (4) it is vital to have a discrimination term which can determine whether the buyer’s replenishment cycle time is less than the permissible delay period or not. We then derive the necessary and sufficient conditions to obtain the optimal solution, and establish some theoretical results to characterize the optimal solution.

     Finally, in chapter 4, we propose a deteriorating inventory model for a seller by incorporating the relevant fact that deteriorating items with maximum lifetime to find the optimal credit period and cycle time in a supply chain. Meanwhile, we also incorporate the following relevant facts: (1) deteriorating products not only deteriorate continuously but also have their maximum lifetime, and (2) credit period increases not only demand but also default risk. We then characterize the seller’s optimal credit period and cycle time. Furthermore, we discuss a special case for non-deteriorating items.Additionally, in all above three models, we run several numerical examples to illustrate the problem and provide some managerial insights.

目錄      I
表目錄  III
圖目錄   IV
第一章  緒論	1
1.1 研究動機與目的	1
1.2 文獻探討	5
1.3 本文結構	8
第二章 在違約風險下之最佳訂購及信用交易策略	10
2.1 前言	10
2.2 符號說明與基本假設	12
2.3 模式建立	14
2.4 數值範例	20
2.5 小結	23
第三章 運用訂購成本降低與延遲付款的策略對整合存貨模式之推廣	24
3.1 前言	24
3.2 符號說明與基本假設	26
3.3 模式建立	28
3.4 數值範例	39
3.5 小結	41
第四章 具最大壽命期限退化性存貨之最佳訂購及信用交易策略	43
4.1 前言	43
4.2 符號說明與基本假設	45
4.3 模式建立	47
4.4 理論結果與最佳解	50
4.5 特例：非退化性貨品	54
4.6 數值範例	56
4.7 小結	58
第五章 結論	59
5.1 主要研究成果	59
5.2 未來研究方向	63
參考文獻	66
附錄 A  79
附錄 B  80
附錄 C  83
附錄 D  84
附錄 E  86


表1.1 民國100年底全體民營企業資產負債統計表	1
表2.1 敏感度分析表	22
表3.1 參數t之敏感度分析	39
表3.2 參數Sv 之敏感度分析	40
表3.3 參數F之敏感度分析	41
表4.1 各參數之敏感度分析	56

圖3.1 賣方的存貨情形	30
圖3.2 允許的延遲付款時間(t)  補貨週期(T)	31
圖3.3 允許的延遲付款時間(t) >補貨週期(T)	33
圖4.1 存貨系統圖形示意圖	48

一、中文部分

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