不良損失을 고려한 多段階 로트生産의 生産스케줄 樹立에 관한 硏究 : 신발類 製造業體를 實例로 in a Case of Shoes Production = A Study on the Scheduling of Multistage Lot Production with Defective Losses

다국어 초록 (Multilingual Abstract)

The competitive strategy of an organization is represented by its policies with respect to the marketplace and its competitors; four major competitive weapons are cost, quality, availability and flexibility. For intermittent system, when the quality and flexibility are almost equal among competitors, cost and availability are critical factors to have advantage over other competitors.
Intermittent system has two important characteristics regarding availability and cost. One is learning curve phenomenon and the other is scrap factor in production process. So, in this paper a model which finds the efficiency of system is proposed to represent competitive power from availability and cost which are under the influence of learning curve phenomenon and scrap factor.
Especially, scrap factor is the cause of delay of order delivery and increase of cost and resulted in the deterioration of productivity. On the other hand learning, curve phenomenon in production process of one kind of item reduces the production time and costs. So, this paper has the idea to represent opportunity cost of waiting time of order and defective losses into profitability of system under certain scheduling rule. Besides profitability, average number of waiting orders and average waiting time of an order are considered as systems efficiency.
To find profitability as profit per systems hour, the difficulty lies in to find out the waiting time of orders. Two methods are considered. One is by analytic queueing M/G/m model or Level Cross Analysis model. The other is Simulation model. Queueing model is difficult to accommodate practical real requirements into theoretical model and to expand mathematically. So, Simulation model is constructed.
The imput variables are learning curve percentage (R), defective rate (p), set-up time (UP), rate of return (r), prices (P), raw material and labor costs (C), and feedback probability (d) to complete scrap deficiency. When these input variables are given, the simulation model finds the profitability, idle time of facilities, average number of waiting order (N), average waiting time (W),etc. Through numerical example of shoes production case, it was found out that scrap factor has severe influence on profitability than expected, and average number of waiting order was greatly influenced by systems utilization factor (ρ) and average waiting time was consistently stabled through the experiment.
In addition, if we have practical past history of order arrival and order size, these data can be used to generate order arrival data, we can get profitability and other important systems characteristics which give some important information about the operation of intermittent productive system such as order processing rule or scheduling priority rule.

목차 (Table of Contents)

• Ⅰ. 硏究目的
• Ⅱ. 接近方法
• Ⅲ. 注文生産시스템의 模型
• 1. 模 型
• 2. 戰 略
• Ⅳ. 注文生産시스템의 收益性 評價 方法
• Ⅴ. 待期行列 模型을 이용한 分析의 가능성
• 1. M/G/m 模型
• 2. Level Crossing Analysis를 이용한 方法
• Ⅵ. Simulation 模型을 이용한 收益性 評價
• 1. Simulation 模型의 가정
• 2. 學習曲線 現象과 不良率
• 3. 收益性을 고려한 로트의 投入量 決定
• 4. Simulation 模型의 수립
• 5. Simulation 模型의 실례
• Ⅶ. 結 論
• 參考文獻
• Summary
• 부록