USING CONTROL THEORY TO EXPLORE THE BULLWHIP EFFECT IN THE SUPPLY CHAIN FOR A DETERIORATING PRODUCT

[[abstract]]企業的產能、存貨控制管理，對於其成本控制佔有極大的角色地位，對存貨進行有效的控制管理，能提升本身的競爭優勢。藉由高效率的生產存貨控制系統，使生產者面對多變化的市場需求時，對於降低存貨，節省成本，及市場上的競爭力，皆有相當大的幫助。生產者依市場需求進行預測，制定生產計劃；但往往由於許多因素造成生產產能與實際市場需求的落差，而使存貨數量波動幅度不斷擴增，產生所謂的長鞭效應現象。本研究提出如何訂定生產策略及控制存貨，以期改善長鞭效應。 本研究探討兩層供應鏈體系，單一製造商、單一市場及單一產品，由市場需求產生訂單數量，製造商根據存貨水準及訂單數量進行生產計劃。研究方法利用自動控制理論，設計生產存貨控制系統，針對具有庫存損耗性產品，根據營運者設定的存貨水準及產品需求函數，決定生產率，以期在不同的需求型態下，降低存貨波動，減低長鞭效應現象。其中，使用拉普拉斯定理，在時域討論生產策略對於不同型態需求的影響，利用模式推導及模擬顯示，以改善需求對於存貨數量波動的影響。 使用本研究發展的生產存貨控制系統，可得到以下結論： 一、系統決定的生產率較佳， 二、產品存貨數量波動，可經由系統調整改善。 三、生產率型態影響長鞭效應改善程度。[[abstract]]Managing capacity and inventory in enterprises have a significant impact on the total systemwide costs. The effective management of inventory can improve one's own competition advantage. Effective inventory control system make producer at market demand that change more, for reducing stocks, save the cost, and the competitiveness on the market, all have sizable help. Producers predict in accordance with market demand to make the production schedule, having a lot of factors lead to make the fluctuating range of the quantity of the stock increase constantly, produce the bullwhip effect phenomenon. This paper proposes how to make the production schedule and control inventory, in the hope of improving the bullwhip effect. We consider a manufacturer, single market and single product in two layers supply chain. Produce the quantity of the orders by market demand, and manufacturers make the production schedule according to the orders and inventory level. Use control theory to design the inventory control system for deteriorating products. Expect reduce stocks and fluctuate under different demand type, improve the bullwhip effect phenomenon. We discuss the production schedule for different demand type in time-domain by Laplace transform, and use model simulations express stocks and improve fluctuations. We can get the following conclusions: First, the productivity determined systematically is relatively good. Second, the quantity of products stock fluctuatally can be improving by system. Third, the productivity type attitude influences the improving degree on bullwhip effect