汰換是指將舊世代產品更替成新世代產品，而汰換策略與汰換時機則會受到市面上產品更新的速度影響，在現今科技進步、環保意識與法令要求等多方面因素影響下，市面上產品更新的速度越來越快生命週期也因此縮短。而過去在討論到汰換策略時，通常是以市面上同時存在有兩種或多種產品可供選擇的情況下進行決策及分析，但在產品生命週期縮短的情況下可能提早面臨舊世代產品停產或是下市的情況，也因此會影響到最佳汰換時機，故本研究基於舊世代產品較具成本效益卻即將停產的情況下，提出結合存貨後的汰換策略。一般而言產品大致可分為不可維修產品與可維修產品，當不可維修產品面臨失效時通常直接以相同產品置換或是選擇汰換成新世代產品；當可維修產品失效時則可以選擇維修、置換或汰換。本研究主要探討在週期性置換策略下，可維修產品在舊世代在即將停產時，透過採購存貨來延長舊世代產品的使用時間，尋求最佳訂購量、置換週期、與汰換時機，使得期望總成本最低。

“ Switch-over ” means that an old gerneration product is replaced by a new generation product. With the progress of technology and environmental protection policy, product lifecycle becomes shorter than before, and some old generation products may phase out eventually. Most research related to switch-over policy usually focused on the case where the old and the new generation products are simultaneous on the market. Due to the short lifecycle, this research will deal with the situation that the old genertation product has better cost efficiency than the new one and is going to be end-of-life (out-of-market). In the situation, we propose to purchase inventory to enlong the usage of the old generation products. In this research, we consider a reparable product, which is replaced periodically and minimal repairs are performed whenever it fails. When the product is cost efficient and going end-of-life, our objective is to derive the optimal inventory level, replacement period, and the time to switch over to the new generation product, such that the expected total cost is minimized.

[1] 陳柏廷，「新世代購買成本與汰換成本隨時間變動下產品之最佳汰換時間」，國立台灣科技大學工業管理系碩士論文 2020。
[2] 張嘉文，「汰換為新世代產品之最佳時間」，國立台灣科技大學工業管理系碩士論文 2019。
[3] 顧尚芳，「生產系統中利用製程不良率評估設備預防維護之研究」，中原大學工業與系統工程研究所碩士論文 2003。
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