Browsing by Author "Wu, C. H."

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3D Modeling of Flood Induced Flows and Sediment Concentration in Shihmen Reservoir
(2008)
Wang, K. H.
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Yang, J. C.
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Wu, C. H.
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土木工程學系
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Department of Civil Engineering
Hydrodynamic and sediment transport modeling is important to the analyses of the aggradation and degradation of a river system, the sediment management in a reservoir, and the study of downstream effect on the coastal sediment. This paper presents a development of a three-dimensional hydrodynamic and sediment transport model to investigate the variation of sediment concentration in Shihmen Reservoir in Taiwan under typhoon induced flood events. The fundamental equations that govern fluid flows and sediment concentration are the Reynolds-averaged Navier-Stokes (RANS) equations and sediment transport equation. Model equations are solved by using an implicit, finite-difference scheme in a curvilinear and vertically stretched coordinate system. A case study of Shihmen Reservoir utilizing the present flow and transport model is presented. The upstream flow-rate conditions are obtained from the data recorded during the 2005 Typhoon Haitang. The computed results clearly reflect the three-dimensional feature of the velocity field in the reservoir. The predicted time-varying water surface elevation during the 140-hour flood event agrees well with measured data. For the sediment concentration, only limited measurements in the domain are available. When comparing with the measured data, the present model is capable of providing reasonable predictions on the rising trend of sediment concentration during the period that flow rate increases, however, the model overestimates concentration values at the recession stage when the measurements of sediment concentration are shown in the decreasing trend. Other results showing the time variation of the velocity vectors and sediment concentration at selected vertical layers are presented and discussed.
A Close Form Solution for the Product Acceptance Determination Based on the Popular Index C-pk
(2013-07-01)
Pearn, W. L.
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Wu, C. H.
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工業工程與管理學系
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Department of Industrial Engineering and Management
Product acceptance determinations are practical tools for quality control applications involving quality contract on product orders between the vendor and the buyer. It provides the vendor and the buyer rules for product acceptance to meet the preset product quality requirement. As the rapid advancement of manufacturing technology, more than one quality characteristic must be simultaneously considered to improve the product quality because of the product design. In this article, we introduce an efficient product acceptance procedure on the basis of the generalization C-pk(T) index, to deal with lot sentencing problem with very low fraction of defectives. We tabulate the required sample size n and the corresponding critical acceptance value c(0) for various alpha-risk, beta-risk, and the levels of the lot fraction of defectives that correspond to acceptance and rejecting quality levels. Practitioners can use the proposed method to make reliable decisions in product acceptance. Copyright (C) 2012 John Wiley & Sons, Ltd.
A Note on "Capability Assessment for Processes with Multiple Characteristics: A Generalization of the Popular Index Cpk"
(2013-03-01)
Pearn, W. L.
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Wu, C. H.
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Tsai, M. C.
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工業工程與管理學系
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Department of Industrial Engineering and Management
The generalized yield index C-pk(T) establishes the relationship between the manufacturing specifications and the actual process performance, which provides a lower bound on process yield for two-sided processes with multiple characteristics. The results attended are very practical for industrial application. In this article, we extended the results in cases with one-sided specification and multiple characteristics. The generalized index C-PU(T) was considered, and the asymptotic distribution of the natural estimator (C)over-cap(PU)(T) was developed. Then, we derived the lower confidence bounds as well as the critical values of index C-PU(T). We not only provided some tables but also presented an application example. Copyright (c) 2012 John Wiley & Sons, Ltd.
A note on production yield measure for multiple lines
(2016)
Pearn, W. L.
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Tai, Y. T.
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Wu, C. H.
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工業工程與管理學系
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Department of Industrial Engineering and Management
In today\'s globally competitive environment, processes involving multiple manufacturing lines are quite common due to economies of scale considerations. Production yield measure indices C-pk and C-pu are the most popular yield-based indices and have been widely used in manufacturing industries for two-sided and one-sided specification limits, respectively. In this paper, two production yield indices for multiple lines C-pk(M) and C-pu(M) are considered and the approximate distributions of two natural estimators C-pk(M) and C-pu(M) are derived. For the convenience of industry applications, the lower confidence bounds and critical values are provided.
A powerful test for two-sided multiple independent characteristics supplier selection problem
(2015-03-04)
Wu, C. H.
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Pearn, W. L.
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Chuang, C. C.
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工業工程與管理學系
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Department of Industrial Engineering and Management
In this article, we consider the supplier selection problem for two-sided processes with multiple independent characteristics. We review the existing division method and develop a new exact approach called the subtraction method. For practical applications, a two-phase selection procedure is established based on the subtraction method. The decision powers of two methods are compared. We show that the subtraction method we proposed is indeed more powerful than the existing division method. Several figures are presented to display the required sample sizes with various powers and various values of (C-pk1(T), C-pk2(T)). For the convenience of practitioners, the required sample sizes for the two methods with various powers and various values of (C-pk1(T), C-pk2(T))) are also tabulated.
An Effective Procedure for Supplier Selection Applied to Glass Substrate Processes with Multiple Lines
(2014-11-01)
Pearn, W. L.
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Wu, C. H.
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Chuang, C. C.
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工業工程與管理學系
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Department of Industrial Engineering and Management
In this paper, we consider a supplier selection problem, which compares two glass substrate processes with multiple lines and selects the one that has a higher capability. A test statistic obtained by a subtraction method is employed to establish a hypothesis test with two phases. Critical values of the test are obtained to determine the selection decisions. Sample sizes required for various designated selection powers and confidence levels are also investigated. Practitioners can use the proposed method to make reliable decisions. This paper presents a real-world case of a glass substrate process. The selection procedure uses data to reach a decision in supplier selection. We compare the results of the division method to the proposed subtraction method. The results show that the proposed subtraction method is indeed more powerful than the division method.
An Extension of the Product Acceptance Determination for One-Sided Process with Multiple Characteristics
(2013-03-01)
Pearn, W. L.
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Wu, C. H.
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Hung, H. N.
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Kao, C. M.
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統計學研究所
In statistical quality control, product acceptance determination is an important problem for producer and consumer. In practical, particularly more than one quality characteristic must be simultaneously considered to improve the product quality because of the product design. In this article, we investigate the lot sentencing problem for normally distributed process with one-sided specification and multiple characteristics. We not only provide a simple procedure to help practitioners make reliable decision easily but also tabulate the required sample size and the corresponding critical acceptance value for various producer's and consumer's risks with the capability requirements AQL (acceptable quality level) and LTPD (lot tolerance percent defective). Copyright (c) 2012 John Wiley & Sons, Ltd.
An Improved Manufacturing Yield Measure for Gold Bumping Processes With Very Low Nonconformities
(2019-05-01)
Wu, C. H.
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Pearn, W. L.
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Tai, Y. T.
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工業工程與管理學系
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Department of Industrial Engineering and Management
Nowadays, thinner and slimmer smartphones have been widely applied in daily life. In most portable devices, liquid-crystal display driver integrated circuit (IC) or new touch display driver IC are critical components, in which the gold bumping process is used as an essential interconnection technology and usually outsources to out-sourced assembly and testing factories. In semiconductor packaging manufacturing, due to popular high-definition requirements of display devices, gold bumping processes require very low fraction of nonconformities. For this reason, accurately evaluating the manufacturing yield is very important to guarantee the quality requirements being met. To evaluate the yield of gold bumping processes, the most popular yield index C-pk is widely employed in outsourcing contract arrangements. However, the typical existing nature estimator is a biased estimator and more conservative. In this paper, we provide an unbiased estimator to evaluate the gold bumping manufacturing yield more accurately. Based on the new estimator, we further propose a weighted parametric bootstrap method to obtain a reliable lower confidence bound that is closer to the true manufacturing yield. The new yield assessment can avoid underestimating the gold bumping manufacturing yield and can make more reliable decisions.
Box-Cox Transformation Approach for Evaluating Non-Normal Processes Capability Based on the C-pk Index
(2014-07-01)
Wu, C. H.
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Lin, S. J.
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Yang, D. L.
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Pearn, W. L.
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工業工程與管理學系
In manufacturing quality control and operations management, the process yield plays an important role. The capability index C-pk provides a lower bound on the process yield under the assumption that the process characteristic is normally distributed. When the normality assumption is violated, we can transform the non-normal data into normal data by using an appropriate transformation approach. In this paper, we consider the Box-Cox transformation and compare two estimation methods including the maximum likelihood estimator (MLE) and the method of percentiles (MOP). The performance comparison is based on the coverage rate, the precision, and the accuracy of the process non-conformity percentage evaluation. For various sample sizes and various distributions, several figures are presented to compare these two methods.
Development of rapid and ultrasensitive flexible palladium nano-thin film biosensing electrode for V. Orientalis detection
(2018-12-01)
Wu, C. H.
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Huang, Y. Z.
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Chang, C. Y.
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Chang, C. H.
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生物科技學系
Effect of Selenization Processes on CIGS Solar Cell Performance
(2018-07-01)
Wu, C. H.
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Wu, P. W.
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Chen, J. H.
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Kao, J. Y.
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Hsu, C. Y.
Cu(In, Ga)Se-2 (CIGS) films were fabricated by a two-step process method using sputtering from Cu0.7Ga0.3 and In targets. The metallic precursor structures of In/CuGa/In were prepared, and CuGa film was adjusted to the thicknesses of 150, 200, 250 and 300 nm, in order to optimize the CIGS film. After selenization, three independent CIGS (112), CIGS (220/204) and CIGS (312/116) began to crystallize at similar to 280 degrees C and phase peaks continued growing until 560 degrees C. Experimental results showed that with a single stage selenization method, the excessive stoichiometry of the CIGS films was obtained. Using three sequential stages for the selenization process, with a annealing time of 20 min, the stoichiometry of the CIGS absorbers with the Cu/(In + Ga) and Ga/(In + Ga) showed atomic ratios of 0.94 and 0.34, respectively. The intensity of the (112) XRD diffraction peak became stronger, indicating an improvement in the crystallinity. Raman spectra of CIGS absorbers showed a main peak (174 cm(-1)) and two weak signals (212 and 231 cm(-1)). TEM image for electron diffraction pattern showed that the grains were randomly oriented. CIGS solar cell device prepared with a proper selenization, a maximum efficiency of 12.45% was obtained.
Effects of rapid thermal annealing on the structural properties of TiO(2) nanotubes
(2011-10-15)
Lin, J. Y.
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Chou, Y. T.
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Shen, J. L.
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Yang, M. D.
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Wu, C. H.
The structural properties of TiO(2) nanotubes with rapid thermal annealing (RTA) and traditional thermal annealing in O(2) were studied by X-ray diffraction (XRD) and Raman scattering measurements. From analyzing the line width of XRD and the correlation length of the Raman peak, we demonstrate that RTA can be an effective tool for amorphous-anatase transformation in TiO(2) nanotubes. The Raman peak redshifts and reduces its line width after thermal annealing and RTA, which may involves the reduction of oxygen-related defects. (C) 2011 Elsevier B. V. All rights reserved.
Effects of rapid thermal annealing on the structural properties of TiO2 nanotubes
(2011-10-15)
Lin, J. Y.
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Chou, Y. T.
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Shen, J. L.
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Yang, M. D.
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Wu, C. H.
The structural properties of TiO2 nanotubes with rapid thermal annealing (RTA) and traditional thermal annealing in O-2 were studied by X-ray diffraction (XRD) and Raman scattering measurements. From analyzing the line width of XRD and the correlation length of the Raman peak, we demonstrate that RTA can be an effective tool for amorphous-anatase transformation in TiO2 nanotubes. The Raman peak redshifts and reduces its line width after thermal annealing and RTA, which may involves the reduction of oxygen-related defects. (C) 2011 Elsevier B. V. All rights reserved.
Enhancement of light emission in GaAs epilayers with graphene quantum dots
(2015-01-01)
Lin, T. N.
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Chih, K. H.
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Cheng, M. C.
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Yuan, C. T.
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Hsu, C. L.
A green and one-step synthesis of graphene quantum dots (GQDs) has been implemented using pulsed laser ablation from aqueous graphene. The synthesized GQDs are able to enhance the photoluminescence (PL) of GaAs epilayers after depositing them on the GaAs surface. An enhancement of PL intensity of a factor of 2.8 has been reached at a GQD concentration of 1.12 mg ml(-1). On the basis of the PL dynamics, the PL enhancement in GaAs is interpreted by the carrier transfer from GQDs to GaAs due to the work function difference between them.
Enhancement-Mode GaN MIS-HEMTs with HfLaOx Gate Insulator
(2016)
Lin, Y. C.
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Lin, J. C.
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Lin, Y.
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Wu, C. H.
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Huang, Y. X.
Estimating Process Capability Index C-p with Various Sample Types: A Practical Implementation
(2015-07-01)
Wu, C. H.
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Pearn, W. L.
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工業工程與管理學系
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Department of Industrial Engineering and Management
Process precision index Cp has been used widely in the manufacturing industry for measuring process potential and precision. In practice, sample data with various types such as one single random sample, multiple random samples, control chart samples, and samples with gauge measurement errors may be employed to estimate the Cp index for evaluating the process potential capability. If the process is perfectly centered in the specification range, the percentage of process non-conforming (%NC) can be expressed by Cp index. In this paper, a review for estimating and testing of Cp index is presented. Some efficient MATLAB programs and illustrative examples are also provided for each type of sample data.
Evaluation of GaN HEMT with Field Plate for Reliability Improvement
(2016)
Lin, Y. C.
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Lin, J. C.
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Lin, Y.
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Wu, C. H.
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Chin, P. C.
Gate-First TaN/La(2)O(3)/SiO(2)/Ge n-MOSFETs Using Laser Annealing
(2010-11-01)
Chen, W. B.
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Wu, C. H.
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Shie, B. S.
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Chin, Albert
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電子工程學系及電子研究所
To improve device performance, laser annealing was applied to Ge n-MOSFETs, which gave a low sheet resistance of 68 Omega/sq, a small ideality factor of 1.3, and a large similar to 10(5) forward everse current in the source-drain n(+)/p junction. The laser-annealed gate-first TaN/La(2)O(3)/SiO(2)/Ge n-MOSFETs showed a high mobility of 603 cm(2)/Vs and a good mobility of 304 cm(2)/Vs at a 1.9-nm equivalent oxide thickness.
Gate-First TaN/La2O3/SiO2/Ge n-MOSFETs Using Laser Annealing
(2010-11-01)
Chen, W. B.
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Wu, C. H.
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Shie, B. S.
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Chin, Albert
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電子工程學系及電子研究所
To improve device performance, laser annealing was applied to Ge n-MOSFETs, which gave a low sheet resistance of 68 Omega/sq, a small ideality factor of 1.3, and a large similar to 10(5) forward\reverse current in the source-drain n(+)/p junction. The laser-annealed gate-first TaN/La2O3/SiO2/Ge n-MOSFETs showed a high mobility of 603 cm(2)/Vs and a good mobility of 304 cm(2)/Vs at a 1.9-nm equivalent oxide thickness.
HfSiON n-MOSFETs using low-work function HfSi chi gate
(2006-09-01)
Wu, C. H.
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Hung, B. F.
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Chin, Albert
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Wang, S. J.
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Yen, F. Y.
The authors have developed a novel high-temperature stable HfSix gate for high-kappa HfSiON gate dielectric. After a 1000 degrees C RTA, the HfSix/HfSiON devices showed an effective work function of 4.27 eV and a peak electron mobility of 216 cm(2)/V (.) s at 1.6-nm equivalent oxide thickness, with additional merit of a process compatible with current very large scale integration fabrication lines.