Browsing by Author "Wu, SC"

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A similarity inference method for reducing the cost of pair comparison
(2006-01-01)
Wu, MC
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Wu, SC
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Hsia, TC
;
Hsu, SH
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工業工程與管理學系
Group technology must group similar parts into families. In classifying parts based on their global shapes, the similarity of parts has to be manually measured by performing pair comparison. The cost of exhaustively performing pair comparison is quite high when the number of parts to be grouped is large. This paper proposes interval intersection, a novel similarity inference method that effectively infers the pair-comparison data from a set of known data. Justified by empirical experiments, the proposed method outperforms the previous methods when 31% or more of data is known.
Compatibilization and elastomer toughening of polyamide-6 (PA6)/poly(phenylene ether) (PPE) blends
(1999-10-03)
Chiou, KC
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Wu, SC
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Wu, HD
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Chang, FC
;
應用化學系
In the elastomer-modified (polyamide-6/poly(phenylene ether) (PA6/PPE) = 50/50 blends, poly(styrene-co-maleic anhydride) (SMA) was demonstrated to be an efficient reactive compatibilizer. The G1651 elastomer was shown to be an effective impact modifier to result in superior toughness and heat-deflection temperature (HDT) than is the 1901X elastomer for the SMA-compatibilized blends because G1651 particles exclusively reside within the dispersed PPE phase but 1901X particles tend to distribute in the PA6 matrix and/or along the interface. The apparent average diameter of the dispersed PPE phase is insignificantly dependent on the elastomer content in the G1651-modified blend, whereas it increases with increase of the elastomer content in the 1901X-modified blend. Moreover, there exists a critical elastomer content, 15 phr, for the ductile-brittle transition of the G1651-modified SMA-modified PA6/PPE blends. (C) 1999 John Wiley & Sons, Inc.
Crystallization behavior of syndiotactic polystyrene nanocomposites for melt- and cold-crystallizations
(2002-12-05)
Tseng, CR
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Wu, SC
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Wu, JJ
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Chang, FC
;
應用化學系
Analyses of the effects of montmorillonite (clay) on the crystallinity and crystallization behavior of syndiotactic polystyrene (s-PS) were investigated by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The dispersibility of the clay in s-PS nanocomposites was studied by X-ray and transmission electron microscopy (TEM). The clay was dispersed into the s-PS matrix by melt blending on a scale of 1-2 nm or few tenths-100 nm, depending on the surfactant treatment. On adding clay, the crystallization behavior of the s-PS tends to convert into the beta-crystal from the alpha-crystal after being cold-crystallized because the clay plays a vital role in facilitating the formation of the thermodynamically favored beta-form crystal when the s-PS is cold- or melt-crystallized. This phenomenon leads to a change in a conventional mechanism of molecular packing for the s-PS. Evidently, the clay significantly affects the crystallinity and crystallization behavior of the s-PS. (C) 2002 Wiley Periodicals, Inc.
Domination in distance-hereditary graphs
(2002-01-15)
Chang, MS
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Wu, SC
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Chang, GJ
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Yeh, HG
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應用數學系
The domination problem and its variants have been extensively studied in the literature. In this paper we investigate the domination problem in distance-hereditary graphs, In particular, we give a linear-time algorithm for the domination problem in distance-hereditary graphs by a labeling approach. We actually solve a more general problem, called the L-domination problem, which also includes the total domination problem as a special case. (C) 2002 Elsevier Science B.V. All rights reserved.
Effects of titania content and plasma treatment on the interfacial adhesion mechanism of nano titania-hybridized polyimide and copper system
(2004-06-03)
Chiang, PC
;
Whang, WT
;
Wu, SC
;
Chuang, KR
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材料科學與工程學系
Nano-titania (TiO2) incorporated into polyimide (PI) matrix can significantly enhance the adhesion strength for PI/TiO2 hybrid film and copper system. Surface modifications by various plasma treatments (Ar, Ar/N-2 and Ar/O-2) were also applied in this study to improve the adhesion strength. The Ar/N2 plasma treatment is regarded as the more effective way in promoting the adhesion strength. The maximum adhesion value of 9.53 N/cm was obtained for the PI/TiO2-1 wt% hybrid film with Ar/N-2 plasma treatment. It is enhanced about 10 times as large as pristine PI. Furthermore, by Ar/O-2 plasma treatment, a weak boundary of copper oxide was formed at the interlayer between PI/TiO2 hybrid film and copper which decreases the adhesion strength. The effects of plasma treatment and content of nanosized TiO2 on the adhesion strength between PI/TiO2 hybrid film and copper system were studied. Atomic force microscope and contact angle analyses were used to measure the changes in surface morphology and surface energy as a result of plasma treatment. Besides, the interfacial states of peeled-off polymer side and copper side were investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Based on the result of XPS spectra, the peeled-off failure mode between PI/TiO2 hybrid film and copper was proposed in this study. (C) 2004 Elsevier Ltd. All rights reserved.
Expression, characterization, and purification of recombinant porcine lactoferrin in Pichia pastoris
(2002-06-01)
Wang, SH
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Yang, TS
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Lin, SM
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Tsai, MS
;
Wu, SC
Recombinant porcine lactoferrin (rPLF) was synthesized in Pichia pastoris using a constitutive promoter from the glyceraldehyde-3-phosphate dehydrogenase gene. Strains expressing rPLF with its own signal sequence or with that from the yeast alpha-mating factor (alpha-MF) were able to produce and secrete rPLF, but levels were consistently higher using alpha-MF constructs. In contrast, P. pastoris strains that expressed rPLF without a signal sequence produced the protein in an insoluble intracellular form. Increasing the initial pH of shake-flask culture medium from 6.0 to 7.0 or adding ferric ions to the medium (to 100 muM) resulted irk significant improvements in expression of rPLF from P. pastoris. Expression levels (approximately 12 mg/L) were much higher than those observed from Saccharomyces cerevisiae strains (1-2 mg/L). P pastoris-secreted rPLF was isolated and purified via a one-step simple procedure using a heparin column. The molecular size (78 kDa), isoelectric point (8.8-9.0), N-terminal amino acid sequence, and iron-binding capability of rPLF were each similar to that of native milk PLF. (C) 2002 Elsevier Science (USA).
Far-infrared resonance in split ping resonators
(2004-02-01)
Hsu, AC
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Cheng, YK
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Chen, KH
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Chern, JL
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Wu, SC
We experimentally investigated the resonance effect of planar metallic split ring resonators (SRRs) in the far-infrared region (FIR) (similar to10.6 mum). Experimental results indicated that they exhibit resonance around 10.6 mum, implying negative permeability in the FIR region. Furthermore, the ratio of effective dimensions of the SRR cell and the wavelength of the incident beam was around I which suggested a wide scale independence. This size tolerance is useful in realizing the meta-materials with negative indices of refraction in the optical wavelength domain.
Ion-channeling studies of InAs/GaAs quantum dots
(2005-12-01)
Niu, H
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Chen, CH
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Wang, HY
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Wu, SC
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Lee, CP
Determination of the strains in and around the quantum dots is important both to assess the results of the epitaxially grown thin film and to explain the optical performance of quantum dots samples. A series of InAs/GaAs quantum dots samples were fabricated by MBE in Stranski-Krastanov growth mode. The preliminary results of ion-channeling observations along < 001 > growth direction and < 011 > direction will be presented and discussed briefly. (c) 2005 Elsevier B.V. All rights reserved.
Metal-organic chemical vapor deposition of tantalum nitride barrier layers for ULSI applications
(1995-12-01)
Tsai, MH
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Sun, SC
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Lee, CP
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Chiu, HT
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Tsai, CE
Low-resistivity tantalum nitride (TaN) films were deposited by low-pressure metal-organic chemical vapor deposition (MOCVD) using a new precursor tertbutylimidotrisdiethyl amidotantalum. The surface morphology and the step coverage of TaN films were characterized by scanning electron microscopy. The film deposited at 450 degrees C had nearly 100% step coverage and the step coverage decreased to 25% for the films deposited at 650 degrees C, The carbon and oxygen concentrations are about 10 at.% in the CVD TaN films, as determined by Auger electron spectroscopy. From Rutherford backscattering spectroscopy and secondary ion mass spectroscopy analysis, TaN films were found to be effective diffusion barriers between aluminum and silicon up to 550 degrees C. The electrical measurements of diode-leakage current indicate that the Al/TaN/Si structure remained stable up to 500 degrees C, after which Al started to diffuse through the TaN layer and resulted in a higher leakage current.
Migration-adsorption mechanism of metallic impurities out of chemically amplified photoresist onto silicon-based substrates
(2000-10-01)
Yang, CC
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Ko, FH
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Wang, MY
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Wang, TK
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Wu, SC
The radioactive tracer technique was applied to investigate the migration and adsorption behaviors of metallic impurities (i.e., Ba, Cs, Zn, and Mn) out of chemically amplified photoresist onto silicon-based underlying substrates. Two important process parameters, i.e., baking temperatures and substrate types (e.g., bare silicon, polysilicon, oxide, and nitride) were evaluated. Our results indicated that the transition metals (Zn and Mn) have lower migration ratios than alkali metal (Cs) and alkaline earth metal (Ba), irrespective of the substrate types and baking temperatures. The transition metals form stable complexes with the coexisting solvents and/or hydrolysis species in the photoresist layer. The size of the metal complex, the drag force in solvent evaporation, and the baking process were found to have significant effects on impurity migration. A new model, together with the metal migration in the chemically amplified photoresist and the subsequent adsorption onto the underlying substrate, was proposed to explain the pathway of the metal migration. This model could explain the migration ratios of metallic impurities out of the photoresist layer onto the substrate surface. (C) 2000 The Electrochemical Society. S0013-4651(00)01-026-0. All rights reserved.
Multiaction maintenance subject to action-dependent risk and stochastic failure
(2000-08-16)
Su, CT
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Wu, SC
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Chang, CC
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工業工程與管理學系
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Department of Industrial Engineering and Management
Although Markov maintenance problems have received extensive attention, relatively few studies have addressed multiple nonreplacement maintenance actions for a multistate system with action-dependent risk and stochastic failure. In this study, we closely examine such multiple maintenance actions by viewing a coherent multicomponent system as a multistate system and assuming that each maintenance action regarding state improvement has a probabilistic risk which is ineffective. The above problem is also modeled as a Markov maintenance problem, demonstrating that the optimal maintenance policy has easily computed and implemented control limit rule. More specially, results in this study confirm the practical nature of the proposed model with respect to its ability than most conventional Markov maintenance models for some particular systems. (C) 2000 Elsevier Science B.V. All rights reserved.
Novel determination of the crystallinity of syndiotactic polystyrene using FTIR spectrum
(2001-05-01)
Wu, HD
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Wu, SC
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Wu, ID
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Chang, FC
;
應用化學系
The crystallinity and crystallization behavior of syndiotactic polystyrene (s-PS) alpha- and beta -crystals have been thoroughly examined using the Fourier Transform Infrared (FTIR). It is shown that absorptivity ratio of respective absorbances of "alpha -crystal/amorphous, a(alpha)" and "beta -crystal/amorphous, a(beta)" can be quantitatively determined using FTIR spectra ranging from 865 to 820 cm(-1). Results from curve fitting show that both absorptivity ratios of a(alpha) and a(beta) are 0.178 +/- 0.005 and 0.272 +/- 0.005 for alpha- and beta -crystal absorbances, respectively. The crystallization rate and crystallinity of alpha -crystal calculated from the absorptivity ratios art: higher than that of beta -crystal crystallized at 240 degreesC for the same isothermal duration in thin film sample. The formation of beta -crystal is thermodynamically more favorable while of alpha -crystal is kinetically more favorable from FTIR spectra. (C) 2001 Elsevier Science Ltd. All rights reserved.
Physical and mechanical properties of polyimide/titania hybrid films
(2004-01-30)
Chiang, PC
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Whang, WT
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Tsai, MH
;
Wu, SC
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材料科學與工程學系
Titania-containing polyimide (PI) hybrid films with homogeneous and flexible properties have been fabricated via sol-gel process. Various contents of titania are added to three different PI systems by using acetylacetone to reduce the reaction rate and to prohibit gelation. The thermal, electrical and mechanical properties of the hybrid films will be measured and compared to pure PI. Results indicate that the metal-containing PI possesses lower thermal expansion and resistivity than pure PI. Incorporation of small amount of titania enhances mechanical properties of the hybrid films at both low and elevated temperature. The relationship between the effect of titania concentration, structure and properties will also be discussed. (C) 2003 Elsevier B.V. All rights reserved.
Synthesis and properties of soluble aromatic polyamides derived from 2.2 '-bis(4-carboxyphenoxy)-9,9 '-spirobifluorene
(2003-04-15)
Wu, SC
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Shu, CF
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應用化學系
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Department of Applied Chemistry
The synthesis of a new bis(ether carboxylic acid), 2,2'-bis(4-carboxyphenoxy)-9,9'-spirobifluorene, in which two orthogonally arranged carboxyphenoxyfluorene entities are connected through an sp(3) carbon atom (the Spiro center), is reported. The direct phosphorylation polycondensation of this diacid monomer with various aromatic diamines yields aromatic polyamides containing 9,9'-spirobifluorene moieties in the main chain. The presence of the spiro segment restricts the close packing of the polymer chains and decreases interchain interactions, resulting in amorphous polyamides with enhanced solubility, and high glass-transition temperatures and good thermal stability are maintained through controlled segmental mobility. The glass-transition temperatures of these polyamides are in the range of 234-306degreesC, with 10% weight losses occurring at temperatures above 530 degreesC. (C) 2003 Wiley Periodicals, Inc.
The crystallization characterization of bulk syndiotactic polystyrene sample: immediate evidence from IR spectroscopy
(2004-02-01)
Wu, SC
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Chang, FC
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應用化學系
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Department of Applied Chemistry
The crystallization characterization of bulk syndiothactic polystyrene (s-PS) sample is thoroughly studied using the Fourier transform infrared spectroscopy (FTIR). The WAXD is further used to identify the s-PS crystal formation to confirm the specific absorbance in FTIR spectra. Both melt and cold-crystallization behavior are quantitatively determined using FTIR spectra ranging from 870 to 820 cm(-1) at 264 degreesC. Fitting curves to IR spectra provides direct evidence of bulk s-PS crystallization behavior in quantification. The melt-crystallization process yields the beta-form only; while the cold-crystallization process yields both the alpha and the beta-form crystal in bulk s-PS sample. The beta-form crystal is generated from the phase-transformation of the alpha-form crystal by cold-crystallization process, the alpha-form crystal is the initial phase. The activity energy of the alpha-form formation is lower that that of the beta-form, suggesting that the alpha-form crystal is kinetically favorable while the beta-form crystal is thermodynamically favorable. (C) 2003 Published by Elsevier Ltd.
The effects of low-pressure rapid thermal post-annealing on the properties of (Ba,Sr)TiO3 thin films deposited by liquid source misted chemical deposition
(2001-12-01)
Yang, MJ
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Chien, CH
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Leu, CC
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Zhang, RJ
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Wu, SC
The technique of low-pressure post-annealing process with additional second-step annealing for preparation of the Ba0.7Sr0.3TiO3 thin films deposited by liquid source misted chemical deposition (LSMCD) has been proposed. With employing this annealing procedure, the leakage current density can be significantly eliminated by approximately one order of magnitude at 2 V. In particular, process temperature can be reduced from 650 degreesC to 600 degreesC without suffering deteriorated crystallinity issue, which is identified by both C-V measurement and X-ray diffraction spectrum. The extracted dielectric constant is 310 with extreamly low loss tangent of 0.005. The spectrum of atomic force microscopy (AFM) shows that this low-pressure process results in smoother surface topography. Moreover, thermal desorption spectrums assure that less residual organics and contaminations were left after low pressure post-annealing. This may be one of the reasons for lowering crystallization temperature and the improved electrical properties.