| Summary: | 博士 === 國立雲林科技大學 === 工業工程與管理系 === 102 === The increasing availability of information is making the industrial environment more competitive. As a result, inventory management has become essential. In most practical manufacturing and inventory settings, the generation of defective items is inevitable due to process deterioration or other factors. This study assumes that inventory management related to defective items is accomplished through batching procedures and control over lot-splitting shipments, and screening to prevent defective products from moving to the next manufacturing process. Subsequently, the inventory model must generate a mathematical model that describes the behavior of the inventory system and the extent to which inventory has to be replenished due to defective items.
This study proposes that defective inventory be managed through a model that focuses on the optimal coordination of policies among all partners within a supply chain, all of which have diverse concerns, in order to minimize combined total costs. In this context, the following scenarios are possible: (1) a single inventory model with different defect rates; (2) an optimal inventory and shipment policy for the upstream two-resources supply chain with correlated demands and returns; (3) an optimal inventory and shipment policy for the downstream buyer removing the defective items; (4) a defective item inventory model including remanufacturing or replenishing in an integrated supply chain. Mathematical models are developed for each of these scenarios and the defective items batch-procedures theorem is utilized in the proposed mathematical model to cope with variable cycle lengths. Based on the results, an analytical examination reveals that batching procedures are the best way to remove defective items, numerically showing that a policy of frequent shipments in small lot sizes is less costly than a single-shipment policy.
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