限制理論Demand Pull應用環境之研究

Abstract

限制理論中發展出來的Demand Pull「拉式」補貨模式，主要是將傳統的「推」(Push)的做法改成以「拉」(Pull)的觀念，此做法確實能對配銷及庫存管理帶來不錯的績效。過去許多文獻已經充分證明限制理論Demand Pull的拉式補貨機制是很好的補貨方法，能有效大幅改善缺貨率、降低平均庫存並且增加產品可得性。然而，現實的市場環境非常複雜，存在許多不同的配銷情況，而任何一個良好的機制要有效運作，必須應用在符合該機制的假設環境下才能有效發揮其作用，若使用在不符合其假設的環境，再好的機制也無法得到預期的效果。雖然Demand Pull拉式補貨的方式過去已有很多文獻充分證明其績效，但並未對Demand Pull之應用環境提出說明或探討，而過去的研究更鮮少考慮產品具有壽命週期的特性，因此本研究主要針對「補貨前置時間」與「產品壽命週期」之比例對Demand Pull績效之影響進行探討，藉邏輯推導及模擬後，確認過短的「補貨前置時間」與「產品壽命週期」比例會影響Demand Pull的績效，甚至無法執行，並藉由模擬結果說明在RLT與PLC之比例在多少範圍下，Demand Pull才能有效地操作。

One of the replenishment methods, Demand Pull, is developed from Theory of Constraints. It mainly transforms the method from the traditional “Push” idea to “Pull” concept and brings positive result to distribution and inventory management. Numerous literatures prove that Demand Pull is an useful replenishment method for improve the out of stock situation, lower the average inventory level and increase the product availability. However, actual market is very complex that contains various distribution situations. Moreover, useful method can only be effective under certain hypothesis circumstances. If the condition is not suitable, such useful method will not able to deliver desired outcome. Although the effectiveness of Demand Pull has been proven by numerous literatures, there is no research regarding exploration of its applicable condition, especially lacking the consideration of product life-cycle characteristic into the analysis. Therefore, this research will mainly focus on the influence between the proportion of replenishment lead time and product life cycle to Demand Pull. Based on logical inference and imitation, author finds that if the proportion of replenishment lead time and product life cycle is too short, it will affect the effectiveness of Demand Pull and even cause the failure of implementation. The result of imitation also demonstrates the suitable proportion range of RLT and PLC that makes the Demand Pull method functions effectively.