本論文在解決產品回收數量與時間不確定的問題。由於近年來，環保意識抬頭，逆物流已成為二十一世紀極重要的課題。許多企業為了提升顧客服務水準、節省成本及符合政府的法令限制，對於逆物流越來越重視。而在逆物流中產品回收以及再製造的各個過程中，產品回收數量與時間的不確定都會對再製造商存貨策略帶來相當大的影響。因此本論文使用Arena模擬軟體，模擬再製造流程，討論當再製造商有兩個物料來源時，一為自己公司內部回收，二為向外面回收商購買，在最小成本下回收率與最佳存貨策略的關係，使公司能提高顧客滿意度以及降低成本。

Reverse logistic have received increasing attention in the last few decades since extreme uncertainty of recycling and remanufacturing processes bring significant impact to inventory management. The thesis considers the (s,S) periodic review policy for a pull inventory with demands following Gamma distributions, new materials with used materials to produce new items. The used materials have two supply sources; one is internal recycling, the other is external procurement from a recycling company. We use the Arena simulation software to model the remanufacturing process. Objective of this (s,S) inventory management system is to control external old materials order and the internal recycle quantities that minimize the total expected costs. We also study the relationship between recycle rate and inventory in the situation that remanufacturer has two material sources.

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