由於半導體公司的利潤被壓縮，半導體公司開始使用各種方法來增加公司的生產利潤。有些公司開始使用控制物料等候時間門檻的方法來增加生產利潤，這個方法就是對物料的等候時間設定一個限制門檻，如果物料在等候線上的時間超過這個門檻，就報廢或是用其他的方式處理。這個方法可以增加製造完成品的成功率，而且也可以節省等候線上的空間。 本論文研究用M/G/1等候系統去建立一個利潤模型，然後用三個策略去分析；控制物料到達率策略、先進先出的等候時間門檻策略、後進先出的等候時間門檻策略。首先我們分析控制物料到達率對系統的影響和極大單位時間利潤，然後發展此模型到物料先進先出和後進先出的情況下求最佳的等候時間門檻使單位時間利潤極大化。最後再進一步比較物料先進先出的等候時間門檻策略和物料後進先出的等候時間門檻策略的不同。 Semiconductor companies use many kinds of methods to administrate their yield profit. Some semiconductor companies have used a method of controlling waiting time thresholds in the queue already. They use a threshold policy to limit the waiting time materials spend in the queue. If a material spends the time over the time thres- hold, the material will be discarded. It is in order to decrease the defective materials are processed by the machine and increase some useful space in the queue. In this thesis, we develop a profit model as an M/G/1 queuing system. Three policies are used in our thesis: arrival rate control policy, waiting time threshold policy with first-come-first-serve, waiting time threshold policy with last-come -first-serve. We control the arrival rate of materials to maximize the profit earned per unit time and analysis its effect. Then, we use waiting time threshold policy with first- come-first-serve and waiting time threshold policy with last-come-first-serve to find the optimal waiting time threshold and find the optimal profit earned per unit time. Finally, the comparison of two threshold policies is showed.
