本論文主要研究探討年齡回溯法下設備生命週期內之最佳維修策略與租賃長度。出租者與承租者在簽訂設備租賃契約條款時的重要項目包含設備的維修保養服務、設備租金與租期長度等。一般而言，設備的租賃契約中會明訂出租者須負擔的維修責任、承租者所能容忍的設備故障維修時間及出租者維修逾時的懲罰性賠償等。對於租賃設備的整體支出與收入，設備的預防保養執行可有效的降低設備的故障次數並減少支出成本，租賃設備的租期長度則是出租者的主要收入。有鑑於此，本論文以出租者立場針對可維修的租賃設備，考慮租期內設備故障時採小修方式處理，引進週期性預防保養策略並加入出租設備可得之收入，建構出設備在租期內整體總利潤的數學模式。依據建構之利潤模式尋求最佳預防保養策略與租期長度，並以數值分析結果說明最佳預防保養策略與租期長度對利潤模式之影響。

This paper examines preventive maintenance policies and the optimal length of a lease period from the lessor’s perspective. The length of the lease period, the repair time of the failed equipment, and rent for the leased equipment are detailed in the lease contract. To achieve steady revenue, the lessor may provide a discount to encourage the lessee to sign a contract with a long lease period. For the lessor, determining the frequency of preventive maintenance and the length of the lease period is crucial. Therefore, we consider the following maintenance scheme in this study. Within the lease period, all equipment failures are repaired minimally. A repair time that exceeds a prespecified tolerable time results in a penalty to the lessor. Within the lease period,the lessor preventively
maintains the equipment periodically. Based on this maintenance scheme, a mathematical model of the expected total profit for the equipment within the lease period is developed and the optimal length of the lease period and corresponding optimal maintenance policy are determined. Finally, we
peovide numerical examples to illustrate the effects of the lease period length and the maintenance policy on the expected total profit.