| Summary: | 博士 === 淡江大學 === 管理科學學系博士班 === 102 === For the sustainability of this globe we all live in, effective end-of-life value realization is essential. Reuse is considered the most environmentally beneficial way of product recovery. On the other hand, the rapidly changing technologies and fierce competition characters of modern manufacturing results in the market with a lot of younger and better used products. However, the concerns over the quality of the second-hand products hinder the development of second-hand product market. Quality can be classified into two types: customer-driven quality and engineered quality. This study uses warranty and upgrade action (or preventive maintenance) as the way to improve customer-driven and engineered quality respectively. For the manufacturers, considering the age at the end of first life as stochastic, this study develops a profit model. Relevant costs like purchase of the used item, surface polish, upgrade and the minimal repair during the warranty period are included. Optimal upgrade threshold value and warranty length are jointly derived so that the expected profit per recovered item can be maximized. For individual consumer, this research develops two periodical age reduction preventive maintenance cost models for practitioners to choose based on the easiness of the implementation. The objective is to determine the optimal number and degree of preventive maintenance, so that the expected cost (including preventive maintenance and minimal repair) for a pre-determined usage period can be minimized. Structural properties are investigated for both manufacturer’s and individual consumer’s models; algorithms are provided to search for the optimal solutions of some special cases. To demonstrate the feasibility and the advantages of the proposed approach, practical application is illustrated. Sensitivity analyses regarding the important parameters are also conducted through various numerical examples.
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