Browsing by Author "Chou, YC"

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Analytic approximations ford multiserver batch-service work-stations with multiple process recipes in semiconductor wafer fabrication
(2001-11-01)
Huang, MG
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Chang, PL
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Chou, YC
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經營管理研究所
;
Institute of Business and Management
This study extends previous results for batch-service workstations to batch-service/batch-lot workstations with multiple process recipes, e.g., diffusion operations in semiconductor manufacturing. The model considered herein explicitly considers the existence of a manufacturing operation associated with multiple process recipes in the semiconductor factory. Consequently, the revised balance equations are submitted and an improved approximation is presented for this case. Based on a comparison with simulation results, this new approximation is shown to be superior to the previously developed analytical approaches. This new approximation is especially strong in cases where the number of process recipes grows, system traffic intensity is moderate, and arrival rate of each recipe is nearly the same.
Buffer allocation in flow-shop-type production systems with general arrival and service patterns
(2002-02-01)
Huang, MG
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Chang, PL
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Chou, YC
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經營管理研究所
;
Institute of Business and Management
This study investigates the buffer allocation strategy of a flow-shop-type production system that possesses a given total amount of buffers and finite buffer capacity for each workstation as well as general interarrival and service times in order to optimize such system performances as minimizing work-in-process, cycle time and blocking probability, maximizing throughput, or their combinations. In theory, the buffer allocation problem is in itself a difficult NP-hard combinatorial optimization problem, it is made even more difficult by the fact that the objective function is not obtainable in closed form for interrelating the integer decision variables (i.e., buffer sizes) and the performance measures of the system. Therefore, the purpose of this paper is to present an effective design methodology for buffer allocation in the production system. Our design methodology uses a dynamic programming process along with the embedded approximate analytic procedure for computing system performance measures under a certain allocation strategy. Numerical experiments show that our design methodology can quickly and quite precisely seek out the optimal or sub-optimal allocation strategy for most production system patterns. Scope and purpose Buffer allocation is an important, yet intriguingly difficult issue in physical layout and location planning for production systems with finite floor space. Adequate allocation and placement of available buffers among workstations could help to reduce work-in-process, alleviate production system's congestion and even blocking, and smooth products manufacturing flow. In view of the problem complexity, we focus on flow-shop-type production systems with general arrival and service patterns as well as finite buffer capacity. The flow-shop-type lines, which usually involve with product-based layout, play an important role in mass production type of manufacturing process organization such as transfer line, batch flow line, etc. The purpose of this paper is to present a design methodology with heuristic search and imbedded analytic algorithm of system performances for obtaining the optimal or sub-optimal buffer allocation strategy. Successful use of this design methodology would improve the production efficiency and effectiveness of flow-shop-type production systems. (C) 2001 Elsevier Science Ltd. All rights reserved.
Computing the noncentral beta distribution with S-system
(2000-06-28)
Chen, ZY
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Chou, YC
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管理科學系
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Department of Management Science
Based on the recasting techniques of Rust and Volt (1990, J. Amer. Statist. Assoc. 85, 572-578), an S-system form of the noncentral beta distribution is extended from that of the noncentral F distribution and the other one is newly derived. The computing methods of this distribution have received much attention during the last decade. Its cumulative probabilities, densities, quantiles and related distributional values can be calculated in one S-system form. We demonstrate the new computational results using the S-system numerical solver ESSYNS. Consistent results are obtained from these two S-system forms under various situations. In addition, we compare the performance with an ad hoc computing method by evaluating the cumulative probabilities and densities jointly. The S-system formulation provides significant numerical advantages over its original form. Further properties are also discussed (C) 2000 Elsevier Science B.V. All rights reserved.
Fast algorithm for evaluating the similarity of manufacturing processes within a dynamic production environment
(2003-11-20)
Huang, MG
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Chang, PL
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Chou, YC
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經營管理研究所
;
Institute of Business and Management
To achieve efficient and economical production, planners and/or designers of production systems frequently must evaluate manufacturing process similarities for various products that they intend to produce. Such work is particularly important in product-mix production, which is widely used in various production systems, including product-oriented repetitive manufacturing, cellular manufacturing, and process-oriented manufacturing. A new potential application for evaluating manufacturing process similarity is necessary in dealing with capacity exchange between rush orders and prescheduled orders. Traditionally, most evaluating methods assumed an essentially static environment, and merely compared the manufacturing routing, processing time and demand. Meanwhile, other more complex evaluating methods were simply impractical. This study suggests a relatively simple but practical method for evaluating the manufacturing process similarity within a dynamic bucketed production environment. The proposed algorithm considers load projection and workstation utilization in terms of a current production schedule. Finally, a real numerical instance is cited to illustrate the effectiveness of the proposed approach.
Gene transfection and expression in a primary culture of mammary epithelial cells isolated from lactating sows
(2005-07-01)
Sun, YL
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Lin, CS
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Chou, YC
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生物科技學系
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Department of Biological Science and Technology
Porcine mammary epithelial cells (PMECs) were isolated from lactating sow mammary glands and cultured on a matrix gel. Primary culture cells expressed significant amounts of the specific marker cytokeratin as determined by immunohistochemistry, and exhibited mammary-specific functions, such as transcription of alpha-lactalbumin, beta-casein and beta-lactoglobulin genes. They also formed mammospheres when the medium was supplemented with lactogenic hormones. The PMECs were used to study gene transfer and expression in vitro. A gene encoding enhanced green fluorescent protein (EGFP) was used as a reporter and two constructs were investigated, pEGFP-N1 (a vector constructed with a CMV promoter followed by the EGFP gene) and pGB562/GFP (a mammary gland-specific expression vector with regulatory sequences from the goat beta-casein gene linked to EGFP). The efficiency of DNA transfer into the cultured PMECs was about 20-30%. GFP expression in the pGB562/GFP-transfected PMECs was markedly stimulated by prolactin supplements in the medium. The established PMECs maintained optimal gene expression from 1 to 20 passages and appeared to provide an efficient and convenient system for assessing the expression of transgenes containing mammary gland-specific promoters. (c) 2005 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.
Nano-oxidation of silicon nitride films with an atomic force microscope: Chemical mapping, kinetics, and applications
(2001-02-15)
Chien, FSS
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Chou, YC
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Chen, TT
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Hsieh, WF
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Chao, TS
We demonstrate that local oxidation of silicon nitride films deposited on conductive substrates with a conductive-probe atomic force microscope (AFM) is a very promising approach for nanofabrication. Scanning Auger microscopy and spectroscopy are employed to verify the chemical changes after AFM-induced oxidation. Furthermore, the growth kinetics are found to have a logarithmic relationship of oxide height versus pulse duration [h proportional to ln(t/t(0))]. In contrast to rather slow thermal oxidation process, AFM-induced oxidation on silicon nitride has an anomalously high initial oxidation rate (similar to 30 000 nm/s at 10 V) and a small onset time t(0) (similar to 10 mus). As for the applications in ultrahigh-density recording, an oxide dot array (similar to 100 Gbit/in.(2)) produced by this process is demonstrated. The nitride film patterned by AFM can be utilized as an etching mask to fabricate "subtractive" silicon nanostructures, due to the large etching selectivity of Si3N4:SiO2:Si in various etchants. With this method, which is entirely compatible with the existing microelectronic processes, synthesis of ultrahigh packing density and ordered nanostructures could become readily achievable. (C) 2001 American Institute of Physics.
Nanomachining of (110)-oriented silicon by scanning probe lithography and anisotropic wet etching
(1999-10-18)
Chien, FSS
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Wu, CL
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Chou, YC
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Chen, TT
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Gwo, S
We have demonstrated that silicon nanostructures with high aspect ratios, having similar to 400 nm structural height and similar to 55 nm lateral dimension, may be fabricated by scanning probe lithography and aqueous KOH orientation-dependent etching on the H-passivated (110) Si wafer. The high spatial resolution of fabricated features is achieved by using the atomic force microscope based nano-oxidation process in ambient. Due to the large (110)/(111) anisotropic ratio of etch rate and the large Si/SiO2 etch selectivity at a relatively low etching temperature and an optimal KOH concentration, high-aspect-ratio gratings with (111)-oriented structural sidewalls as well as hexagonal etch pit structures determined by the terminal etch geometry can be obtained. (C) 1999 American Institute of Physics. [S0003-6951(99)03242-8].
Nanometer-scale conversion of Si3N4 to SiOx
(2000-01-17)
Chien, FSS
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Chang, JW
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Lin, SW
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Chou, YC
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Chen, TT
It has been found that atomic force microscope (AFM) induced local oxidation is an effective way for converting thin (< 5 nm) Si3N4 films to SiOx. The threshold voltage for the 4.2 nm film is as low as 5 V and the initial growth rate is on the order of 10(3) nm/s at 10 V. Micro-Auger analysis of the selectively oxidized region revealed the formation of SiOx. Due to the large chemical selectivity in various etchants and great thermal oxidation rate difference between Si3N4, SiO2, and Si, AFM patterning of Si3N4 films can be a promising method for fabricating nanoscale structures. (C) 2000 American Institute of Physics. [S0003-6951(00)03003-5].
Separation of channel backscattering coefficients in nanoscale MOSFETs
(2004-09-01)
Chen, MJ
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Huang, HT
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Chou, YC
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Chen, RT
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Tseng, YT
Channel backscattering coefficients in the kBT layer (near the source) of 1.65-nm-thick gate oxide, 68-nm gate length bulk n-channel MOSFETs are systematically separated into two distinct components: the quasithermal-equilibrium mean-free-path for backscattering and the width of the kBT layer. Evidence to confirm the validity of the separation procedure is further produced: 1) the near-source channel conduction-band profile; 2) the existing value of kBT layer width from the sophisticated device simulation; and 3) an analytic temperature-dependent drain current model for the channel backscattering coefficients. The findings are also consistent with each other and therefore corroborate channel backscattering as the origin of the coefficients. Other interpretations and clarifications are determined with respect to the very recently released Monte Carlo particle simulation. Consequently, it can be reasonably claimed that the separated components, as well as their dependencies on temperature and bias, are adequate while being used to describe the operation of the devices undertaken within the framework of the channel backscattering theory.