接駁轉運營運系統最佳營運策略之探討

An Investigation on the Optimal Operations Policy of a Cross-Docking Operating System

為滿足顧客需求，一般企業通常以保持存貨減低需求不確定所導致的缺貨問題。以製造業為例，其存貨總值通常占總資產的百分之二十至六十。因此，為提高市場競爭力，如何在滿足既定的服務水準下，有效降低存貨，為每一企業所必須面對的挑戰。傳統存貨管理主要以倉儲營運系統（warehousing operating system）管控存貨量，但自Wal-Mart成功利用接駁轉運營運系統（cross-docking operating system）來降低存貨成本後，愈來愈多產業已改採此新系統。然而不當的營運策略將使得接駁轉運營運系統的效能劣於倉儲營運系統。因此，本研究在假設整個營運系統由中央集中控管的條件下，探討其存貨及運輸管理營運策略；亦即，中央管理者如何制定各零售商之最佳（s,S）存貨政策，以滿足預設的服務水準、降低存貨量、發揮運輸規模經濟效益，進而最小化整個接駁轉運營運系統之總成本。由於制定一供給網路的營運策略是公認的難題，且無法以解析式方法求解。因此，本研究以系統模擬技術求解，並提出一套有效率的求解程序。

To satisfy customers under rapidly changing demands, companies usually keep inventory to reduce the stock-out problem induced by the uncertainty of demands. For example, in the manufacturing sector, inventory often takes up 20% to 60% of the total asset. To sharpen competitiveness, reducing inventory but maintaining a given service level is an important challenge faced by every company. Traditionally, warehousing operating systems are used to control inventory. Ever since Wal-Mart successfully reduces the inventory cost by the cross-docking operating system, more and more companies have adopted this system. However, inappropriate operations can still make a cross-docking operating system perform worse than the corresponding warehousing operating system. Assuming that such a system is under centralized control, this research studies its inventory and distribution policy: A central planner sets the best (s, S) inventory policy that reduces inventory; the policy minimizes the total cost of the system, under economies of scale in transportation, subject to a pre-specified service level. Such a network distribution problem is known to be hard and without analytical solution. Thus, this study solves the problem by proposing an efficient simulation-based solution procedure.