同時處理一般需求與客製化需求之 庫存等候線系統

An Inventory-Queue System Consisting of the MTS and the MTO Productions

胥益騰(Yi-Teng Shiu)

指導教授 ： 張國華

中原大學/工學院/工業工程研究所/碩士(2007年)

https://doi.org/10.6840/cycu200700438

摘要

摘　要
在全球消費性產品供應鏈中，組裝業扮演著非常重要的角色。組裝廠商除了維持計劃性生產(MTS)來滿足一般需求外，往往也被客製化需求要求負責具有多樣性、隨機性又有迅速交貨限制的客製化產品(MTO)。
常見的MTO生產系統屬於拉式生產，其優勢在於零庫存以及能夠滿足客製化之目的，但由於客製化需求到達的發生率較小，有時候是突發性的，常會因工作站使用率過低而造成系統閒置時間過長。
其中一種改善此缺點的方法，即是將MTO生產系統與MTS生產系統二者做適度的「組合」，也就是將MTO系統融入MTS生產線中，成為一種能夠同時處理一般需求以及客製化需求的混合式生產系統。
本研究考慮可同時處理二種需求的單站混合式生產系統。假設一般需求到達系統時，成品庫存區若沒有存貨，則此類顧客將立即離開系統而不等待；當客製化需求到達系統時，則會進入客製化需求等候區等待，直到獲得滿足而離開系統。此混合式生產系統中，MTS部分的庫存區以基本庫存量策略(base-stock policy)進行控制。我們並以一般需求的損失率(loss rate)以及客製化需求的回應時間來評估系統的績效。
假設在混合式生產系統中，二種需求之到達率皆服從卜瓦松(Poisson)分配，工作站之服務時間則服從指數(exponential)分配。本研究以庫存等候線系統對此系統進行探討，在給定的基本庫存量之下，使用矩陣－幾何方法(matrix-geometric method)求解其穩態機率，並求得相關的績效指標，進而制定最佳的基本庫存量水準。

關鍵字

庫存等候線系統 ； 單站 ； 混合式生產系統 ； 基本庫存量

並列摘要

Abstract
Assembly manufacturing played a very important role in the global supply chain of consumer products, such as laptop computers. Assembler, in addition to fulfill the ordinary orders for the regular product by adopting Make-to-Stock (MTS) production, they are often asked to take care the special demands for the customized products by adopting Make-to-Order (MTO) production. However, it is not profitable to maintain a solo MTO production line. Since these customized products are only slightly different from the regular ones, the Assembler usual will consider embedding MTO lines into the main stream MTS lines, which become a hybrid production system. Since the profit for each assembly is very marginal, even with the hybrid lines, the corresponding design and the control issues are curial to the management.

In this study, we assume when an ordinary demand comes, it will not wait for the product if there is none, however, a special demand have to wait for its customized products. In this study, we considered a hybrid MTO/MTS production system with random ordinary and special demands and analyzed it by using the queueing theory. The MTS system deals with the ordinary demands and special demands at the same time. In this hybrid system, the MTS systems are controlled under the base-stock policy. To evaluate the system, we consider the loss rate of the ordinary demands and the waiting time of the special demands. This system is analyzed by modeling them as inventory queueing system. The limiting probabilities are obtained by using matrix-geometric approach and their corresponding performances under base-stick control policy can also be obtained. Furthermore, we can determine the optimal base-stock level numerically.

並列關鍵字

MTO/MTS production ； base-stock policy ； matrix-geometric method ； inventory-queue ； queueing system

參考文獻

參考文獻

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