| Summary: | 博士 === 國立臺灣科技大學 === 工業管理系 === 90 === Because inventory cost is a large proportion of the working capital for many companies, good inventory management by helping corporations to determine the optimal inventory replenishment policies can increase the ability of making profits indirectly. So many researchers were denoted to the development of inventory models.
Under the traditional EOQ model assumes that the retailer must be paid for the items as soon as the items are received. However, in practice the supplier will offer the retailer a delay period, that is trade credit period, in paying for the amount of purchasing cost. Before the end of trade credit period, the retailer can sell the goods and accumulate revenue and earn interest. A higher interest is charged if the payment is not settled by the end of trade credit period. In real world, the supplier often makes use of this policy to promote their commodities.
This article considers some realistic conditions to develop inventory replenishment models and determine the optimal replenishment policies under permissible delay in payments. First, in chapter 2, this article uses the framework of economic production quantity (EPQ) model to investigate the optimal replenishment policies under permissible delay in payments. In chapter 3, this article wants to investigate the effect of trade credit policy with limited storage capacity within the economic order quantity (EOQ) framework. Then, the purpose of chapter 4 is to explore the economic order quantity under supplier credit policies depending on the order quantity. That is, the supplier may give the trade credit period only for large order quantities. In other words, the supplier requires immediate payment for small order quantities. Our inventory model generalizes Goyal [23] and Khouja & Mehrez [32]. Besides, we provide a concrete proof to show that the solution procedure described in Khouja & Mehrez [32] is correct. In chapter 5, combining Goyal [23] and Salameh and Jaber [41], we develop a production / inventory model to allow items with imperfect quality under the conditions of permissible delay in payments. In chapter 6, this article wants to modify Goyal’s [23] model to presume that the unit selling price and the unit purchasing price are not necessarily equal to reflect the real-life situations. In practice, the unit selling price is not lower than the unit purchasing price in general. In chapter 7, this article wants to modify the payment rule of Goyal’s [23] model to adopt different payment rule. Then the result of our model is different with Goyal’s [23] model.
In a word, this article develops six inventory models to determine the optimal replenishment policies under permissible delay in payments and shows that the annual total relevant cost functions or profit functions possess some kinds of convexities or concavities. With those properties, the efficient solution procedures are presented to determine the optimal order quantities speedily and correctly. Finally, numerical examples are given to illustrate all results discussed in this article.
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