Browsing by Author "Chang, SH"

Now showing 1 - 5 of 5

Enhancement of Theory of Constraints replenishment using a novel generic buffer management procedure
(2003)
Yuan, KJ
;
Chang, SH
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Managing a distribution system requires the right inventory in the right place at the right time. A Theory of Constraints replenishment solution is presented to aggregate inventory buffers at the central warehouse in plant and change the mode of operation from push to pull. The solution is powerful, but the optimal amount of buffer remains undetermined. In Theory of Constraints, choosing a specific buffer size is not crucial if the buffer is accurately monitored in a timely manner. Accordingly, Theory of Constraints is offered a buffer management approach for monitoring the buffer. Such buffer management is feasible and effective but is insufficiently rigorous. This paper elucidates a generic buffer management procedure, based on the concept of Theory of Constraints buffer management that rigorously defines a method of monitoring to size and adjust the buffer. An example demonstrates the feasibility of the proposed generic buffer management procedure.
Fiber Bragg grating sequential UV-writing method with real-time interferometric side-diffraction position monitoring
(2005-05-16)
Hsu, KC
;
Sheu, LG
;
Chuang, KP
;
Chang, SH
;
Lai, YC
This work presents a new sequential UV-writing procedure for fabricating long fiber Bragg grating (FBG) devices. To real-time accurately align the position of every exposed FBG section prior to UV exposure, a single-period reference fiber grating with strong refractive index modulation is probed by applying an interferometric side-diffraction method to measure the grating phase as the position reference. In this way the overlapped FBG sections can be connected section-by-section without obvious phase errors, even when the written index-modulation is weak. (C) 2005 Optical Society of America.
Heuristic PAC model for hybrid MTO and MTS production environment
(2003-09-11)
Chang, SH
;
Pai, PF
;
Yuan, KJ
;
Wang, BC
;
Li, RK
Two distinct types of semiconductor plants in Taiwan are integrated device manufacturing (IDM) plants and foundry plants. Most IDM plants are make-to-stock (MTS) operations, focusing on throughput and machine utilization. However, foundry plants are make-to-order (MTO) operations, focusing on due date and cycle time. Besides the challenge of different process technology, the mode of hybrid operation (a combination of MTO and MTS operations) is also a formidable task for these plants. This study develops a heuristic production activity control model to achieve the two different criteria in a hybrid wafer production environment. (C) 2003 Elsevier B.V. All rights reserved.
The construction of production performance prediction system for semiconductor manufacturing with artificial neural networks
(1999-04-15)
Huang, CL
;
Huang, YH
;
Chang, TY
;
Chang, SH
;
Chung, CH
The major performance measurements for wafer fabrication system comprise WIP level, throughput and cycle time. These measurements are influenced by various factors, including machine breakdown, operator absence, poor dispatching rules, emergency order and material shortage. Generally, production managers use the WIP level profile of each stage to identify an abnormal situation, and then make corrective actions. However, such a measurement is reactive, not proactive. Proactive actions must effectively predict the future performance, analyze the abnormal situation, and then generate corrective actions to prevent performance from degrading. This work systematically constructs artificial neural network models to predict production performances for a semiconductor manufacturing factory. An application for a local DRAM wafer fabrication has demonstrated the accuracy of neural network models in predicting production performances.
Use of porous foam as the substrate of an impactor for respirable aerosol sampling
(2005-11-01)
Huang, CH
;
Chang, CS
;
Chang, SH
;
Tsai, CJ
;
Shih, TS
The effect of a porous foam substrate on the penetration characteristics of an impactor with a single round nozzle was investigated experimentally, with liquid and solid particles in the size range of 1-10 mu m. The experimental results show that the cut-off aerodynamic diameter of the impactor with porous foam substrate is lower than that with porous metal substrate due to more air penetration into the porous foam; in addition, the impactor penetration curve is less sharp. A numerical simulation of the penetration curve for the impactor with porous foam substrate was in good agreement with the experimental data. The numerical method was then used to find the best sampling flow rate for respirable aerosol sampling. Results show that when the nozzle diameter is 0.36 cm and the sampling rate is 1.91/min, the penetration curve of the impactor with the porous foam is very close to the criteria for respirable aerosol sampling. (C) 2005 Elsevier Ltd. All rights reserved.