在競爭激烈的銷售市場中，製造商或企業為了吸引消費者購買產品，在功能及外觀上不斷推陳出新，也使得產品的生命週期相較以往而言縮短許多。而對於消費者而言，由於產品功能的不斷出新，使得產品的更換頻率越來越高，市場上可供選用的二手產品也越來越多，由於上述原因，使得消費者在置換產品時，二手產品亦成為選項之一。因此，本論文探討在初用產品已使用年限為已知的情形下，考慮在有限規劃時程下，當產品故障以小修方式處理時，以二手產品置換的最佳置換策略。在同時考慮產品購買時的已使用年限、剩餘價值及產品在使用期間內的期望小修成本下，建立以二手產品置換的兩種置換情境之期望總支出成本模式，依據建構之成本模式尋求二手產品的最佳購買壽期及最佳置換時間，研究結果可提供消費者在置換產品時之參考。

In the competitive product sales market, manufactures keep updating their products on the appearances and functions in order to appeal customers to buy their products. This makes the product life cycle time becomes shorter than before. Based on the above reasons, second hand products become one of the options for customers to change their products. Therefore, this paper investigates the optimal replacement policies for second hand products with residual value under a finite planning horizon (FPH). Within FPH, the product is replaced once by a second hand product and any failure of products is rectified by a minimal repair. After minimal repair, the product is under normal operation but the failure rate of the product remains unchanged. Under these maintenance schemes, the mathematical formula of disbursement cost for a second hand product is derived, and then the optimal policies are obtained such that the expected total cost is minimized. Finally, numerical examples are given to illustrate the influences of the optimal policies for total disbursement cost.

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