當一企業沒有足夠倉儲空間，必須租賃外部倉儲空間來存放存貨時，就會衍生出如何計算出適當的倉儲大小，以及倉儲租借是否影響到平均總成本的變化。因此本研究針對了當企業內部倉儲空間不足，必須租賃外部倉儲空間時，如何計算倉儲空間大小及平均總成本。本研究論文主要提出在共同週期法下，應用固定速率法，求解在經濟批量排程問題中，對於外部倉儲空間大小與平均總成本的求解方式。方法是將一生產週期中多餘的閒置時間適度分配到某項產品，以變更生產速率來減少存貨持有成本和外部倉庫的租賃成本。目前在討論經濟批量排程問題的倉儲空間大小與平均總成本中，已經有針對共同週期法的求解方針，雖然對生產順序的排列組合有嚴格假設，但並沒有詳細討論在共同週期法下，哪一種生產順序會產生較佳的可行解。以往變更生產速率時，在固定速率模式下，會挑選產品中存貨持有成本最高的產品進行降速，影響到的成本項只有存貨持有成本會產生變動。由於本研究探討的是倉儲空間大小與平均總成本，成本項中除了存貨持有成本，也加上了外部倉庫的租賃成本，因此，降速後除了影響存貨持有成本，外部倉庫的租賃成本也會被影響。 本研究將探討在共同週期法下應用固定速率法後，是否在某種生產順序下擁有較佳的可行解，本研究也額外探討在成本項加上外部倉庫的租賃成本的情形下，如何挑選哪個產品做降速，使決策者能在租賃倉庫、計算成本或是進行排程決策上有所幫助。 When a company does not have enough storage space, it must rent outsourcing warehouse space from other companies to store products. If this condition happening, a manager will need to consider (1) how to calculate the correct warehouse size and (2) how does the rent cost affect the average total cost. Therefore, this study discusses the above two issues when a company must rent outsourcing warehouse space from other companies. This research uses the fixed rate approach to solve the warehouse size and average total cost of the economic lot scheduling problem under the common cycle approach. Our approach applied the extra idle time for changing the production rate of one product in order to reduce the holding cost and warehouse rental cost. Most past researchers discussed the two issues above of the economic lot scheduling problem under the common cycle approach. They restrict the sequence all products strictly. However, they did not develop an effective approach for finding an optimal or near-optimal sequence/solution. Past researchers use the fixed rate approach to pick a product with the highest holding cost for changing its production rate. In this study, as applying the fixed rate approach to adjust the production rate of a product, it does not only affect the holding costs, but also impacts the warehouse rent costs.?This study will investigate how to find a better production sequence and solution under the common cycle approach as applying the fixed rate approach. It also discusses how to pick a product in order to change its production rate when considering rent outsourcing warehouse space. Our study can help decision maker to schedule all products sequence, compute the related costs and rent right outsourcing warehouse space.
