在自由開放的競爭市場下，有效的降低企業成本及增加產品的價值是提高競爭力的不二法門。近年來隨著環保意識的抬頭，環境成本佔企業總成本的比重日益增加。環保，就是為了能夠達到物盡其用、不浪費資源，並減少廢料對於環境所造成的負擔。因此，如何利用資源回收與再生來降低相關的物料成本，是企業在提高市場競爭力上另一項考量的重點。本研究主要目的是以可回收性商品之存貨系統為基本架構，考慮單一產品，針對外購商品含有不良品做探討。本研究建立數學模式與利用軟體程式作為求解之工具，並透過數值範例說明與敏感度分析來瞭解影響系統之關鍵因素。試圖尋求出最適當之訂購次數與交貨量，以達到整體總成本最小化。

In this open and competitive market, effective cost reduction and raising product value is the best way to increase competitiveness. In recent years, as the environmental protection cost has risen, the reduction in environmental cost in enterprise is becoming more and more important. One of the ways to save material cost and protect environment is to recycle resources. This study considers the reusable product that has imperfect quality. A mathematical model and a program to derive the minimum cost is developed. Numerical examples and sensitivity analysis are carried out to analyze the key factors in the system.