本篇文章是針對可租賃設備進行維護保養，在考慮其維修成本的情形之下，計算其最佳保養程度及最佳預防保養次數。為了減少設備的故障次數，在租約期間會定期實施檢修的策略，且對於任何故障均進行最小維修。當產品的壽命分配為廣義指數分配時，在期望總成本最低的情形之下，可求得最佳預防保養次數及保養程度。此外，本文亦提供一有效的演算法找出最佳檢修策略。最後，以一個數值例子說明本文所提的檢修策略程序。

The aim of this paper is to discuss the optimal number of preventive maintenance (PM) actions and maintenance degree for a leased facility under maintenance cost. To reduce failures of the facility, we perform some PM actions periodically and any failure is rectified by minimal repair during a leased period. For convince, the lifetime of the facility is assumed to be generalized exponential distribution. Then the optimal number of PM actions and maintenance degree are derived such that the expected total maintenance cost is minimized. Besides, we also provides an efficient algorithm to find the optimal policy. Finally, a numerical example to illustrate our predictable procedure.

參考文獻
[1] Barlow, R.E. & Hunter, L.C.Optimum preventive mathematical policies.Operations Research 8:90-100.

[2] Barlow, R.E. & Proschan, F (1965). Mathematical Theory of Reliability.New York: Wiley.

[3] Boland, Philip J. & Proschan, Frank (1982). PERIODIC REPLACEMENT WITH INCREASING MINIMAL REPAIR COSTS AT FAILURE. Operations Research, 30(6), 1183-1189.

[4] Chun, Y.H. (1992) . Optimal number of periodic preventive maintenance operations under warranty. Reliability Engineering and System Safety, 37 (3), 223-225.

[5] Dekker, R. (1996). Applications of maintenance optimization models: A review and analysis. Reliability Engineering and System Safety, 51 (3),229-240.

[6] Dekker, R., Scarf, P.A. (1998). On the impact of optimization models in maintenance decision: The state of the art. Reliability Engineering and System Safety, 60, 229-240.

[7] Jack, N. (1994). An optimal imperfect maintenance policy over a warranty period. Microelectronics Reliability, 34 (3), 529-534.

[8] Nakagawa, Toshio(1979). IMPERFECT PREVENTIVE-MAINTENANCE. IEEE Transactions on Reliability, 28 (5).

[9] Nakagawa, Toshio, Kowada, Masashi(1983). ANALYSIS OF A SYSTEM WITH MINIMAL REPAIR AND ITS APPLICATION TO REPLACEMENT POLICY. European Journal of Operational Research, 12 (2), 176-182.

[10] Pham, H., Wang, H. (1996). Imperfect maintenance. European Journal of Operational Research, 94 (3), 425-438.

[11] Sherif, Y.S., Smith, M.L. (1981). OPTIMAL MAINTENANCE MODELS FOR SYSTEMS SUBJECT TO FAILURE - A REVIEW.
Naval research logistics quarterly, 28 (1), 47-74.

[12] Sheu, S.-H. (1991). Periodic replacement with minimal repair at failure and general random repair cost for a multi-unit system Microelectronics Reliability, 31 (5), 1019-1025.

[13] Valdez-Flores, Ciriaco(1989).Survey of preventive maintenance models for stochastically deteriorating single-unit systems Naval Research Logistics, 36 (4), 419-446.

[14] Yeh, R.H., Lo, H.-C. (2001). Optimal preventive-maintenance warranty policy for repairable products. European Journal of Operational Research, 134 (1), 59-69.