Browsing by Author "Kang, HY"

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A linear programming model for the control wafers downgrading problem
(2005-02-01)
Chung, SH
;
Pearn, WL
;
Kang, HY
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper considers the control wafers downgrading problem (CWDP) in the wafer fabrication photolithography area. The objective of the research is to minimize the total cost of control wafers, while maintaining the same level of production throughput. For the problem under a pulling control production environment, a linear programming model is presented to set the supply rate of new control wafers and the recycle and downgrading rates so as to minimize the total cost of control wafers. A numerical example is given to illustrate the practicality of the model. The sensitivity of the linear programming model solution to changes in the underlying parameter values is also investigated. The results demonstrate that the proposed model is an effective tool for determining the control wafers downgrading policy. This paper presents a linear programming model that considers the cost of new control wafers, recycle and downgrading control wafers in wafer fabrication. The proposed model improved the performance of control wafers management, and served as the basis for setting the usage rates of control wafers.
A service level model for the control wafers safety inventory problem
(2005-09-01)
Chung, SH
;
Kang, HY
;
Pearn, WL
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper considers the control wafers safety inventory problem (CWSIP) in the wafer fabrication photolithography area. The objective is to minimize the total cost of control wafers, where the cost includes new wafers cost, re-entrant cost and holding cost while maintaining the same level of production throughput. For the problem under pulling control production environment, a nonlinear programming model is presented to set safety inventory levels so as to minimize total cost of control wafers. A numerical example is given to illustrate the practicality of the model. The results demonstrate that the proposed model is an effective tool for determining the service level of safety inventory of control wafers for each grade.
Control wafers inventory management in the wafer fabrication photolithography area
(2005-04-01)
Chung, SH
;
Pearn, WL
;
Kang, HY
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
An important variable affecting the production throughput in the wafer fabrication photolithography area is the work-in-process (WIP) level of control wafers. Previous research work has focused on control wafers downgrading problem, and little work has been done for WIP level of control wafers. The objective of this paper is to develop methods for estimating the WIP level of control wafers for each grade, while maintaining the same level of production throughput. Two factors are considered, the re-entrant of control wafers within the same grade and the downgrading of control wafers among different grades. Under pulling control production environment, a multi-loop algorithm is developed for estimating the WIP control wafers for each grade. We conduct some simulation experiments based on a real-world factory production environment to demonstrate the effectiveness of the proposed algorithm. The results show that the algorithm is an efficient tool for estimating the cycle time and WIP level for each grade of control wafers.