| Summary: | 博士 === 國立臺灣科技大學 === 管理技術研究所 === 86 === In the traditional Economic Manufacturing Quantity model, there is a basic assumption about the production system, that is, the production process is perfect and continuously produces conforming items. This assumption however may not be true in practice. A production system will deteriorate due to usage or age such as corrosion, fatigue and cumulative wear. Under these circumstances, we investigate the effects of imperfect preventive maintenance and free repair warranty on the EMQ model for a deteriorating production system. These two effects are discussed below. 1. The effects of imperfect preventive maintenance on the EMQ model: We consider the case where the shift of the production process is generally distributed and the maintenance action is imperfect and may lead a production system to a worse condition. Two commonly used maintenance strategies are proposed: equally-spaced and equally-cumulative-hazard. Under both maintenance strategies, optimal maintenance policies and the optimal production run length can be obtained. Some numerical examples are also provided to illustrate the performance of the optimal policies. 2. The effects of free repair warranty policy on the EMQ model: Assuming the shift of the production process is exponentially distributed and the products are sold with free minimal repair warranty, we derive an unique optimal production run length which minimizes the expected total cost per item. Three special cases which provide bounds for searching the optimal production run length are investigated and a sensitivity analysis is conducted to study the effects of the model parameters on the optimal production run length. Finally, numerical examples are given to evaluate the performance of the optimal production run length
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