Browsing by Author "Liu, YL"

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An object based authoring tool for creating SCORM compliant course
(2005)
Su, JM
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Tseng, SS
;
Weng, JF
;
Chen, KT
;
Liu, YL
In recent years, how to reuse and share the teaching materials and instructional experiences among e-learning systems become more and more important. Sharable Content Object Reference Model (SCORM), the most popular international teaching materials standard, uses the metadata to specify the structure of every teaming object and proposes the content aggregation scheme to package these objects with XML language format. In 2004, the Sequencing and Navigation (SN) in SCORM 2004 also define the sequencing rules which can be used to control the sequencing, selecting and delivering of teaming activity for the desired, sequencing behavior. Learning contents in SN is organized into a hierarchical structure, namely Activity Tree (AT). However, for teachers/instructional designers, it is hard to understand the complicated sequencing rules in SN much less using it to construct a SCORM course with desired teaming guidance. Therefore, how to provide a user-friendly authoring tool to efficiently construct SCORM compliant course becomes an important issue. Therefore, in this paper, based upon the concept of Object Oriented Methodology (OOM), the complicated sequencing rules can be modularized into several basic components with corresponding sequencing rules in SN, called Sequencing Object (SO). Each SO is like a middleware, which represents a basic sequencing building block as a cluster in activity tree (AT) with some corresponding sequencing rules on the SCORM view and represents a basic sequencing graph on the users' view. By appropriately combining these SOs, users can easily construct a complex structure of course with desired teaming guidance. Then, a transformation algorithm is also proposed to firstly transform the created graph based course structure into Activity Tree (AT) with related sequencing rules, and then package the transformed activity tree and related physical teaming resources into a SCORM compliant course file. Moreover, the authoring tool can be easily upgraded by importing a new SO instead of redesigning the tool only for new SCORM version. Finally, a SCORM compliant course built by the object based authoring tool is executed on the SCORM RTE system. The results show that our approach is workable and efficient.
Dielectric and barrier properties of spin-on organic aromatic low dielectric constant polymers FLARE and SiLK
(2001-06-01)
Wu, ZC
;
Shiung, ZW
;
Wu, RG
;
Liu, YL
;
Wu, WH
This work investigates the dielectric and barrier properties of two species of organic aromatic low dielectric constant (low-k) polymers, namely, FLARE and SiLK. Experimental results indicate that both of the low-k polymers exhibit acceptable thermal stability with respect to a thermal annealing at 400 degreesC for 8 h in an N-2 ambient. Moreover, they show a good dielectric barrier property against Cu penetration under bias-temperature stressing (BTS) at 150 degreesC with an applied effective field of 0.8 MV/cm. Nevertheless, an anomalous instability of the capacitance-voltage curve was observed for the first time under BTS. This finding is explained by the proposed model of stress induced dielectric polarization charges within these organic aromatic polymers. The polarization instability may seriously degrade the long term reliability of circuit operations. (C) 2001 The Electrochemical Society.
Dissociation kinetics of cerium(III) complexes of macrocyclic polyaza polycarboxylate ligands TETA and DOTA
(2000-08-01)
Chang, CA
;
Liu, YL
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生物科技學系
;
Department of Biological Science and Technology
The acid-catalyzed dissociation rate constants of the cerium(III) complexes of 1,4,8,11-tetraazacyclotetradecane-1,4, 8,11-tetraacetic acid (TETA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) have been determined at four different temperatures (i.e., 25.0 degreesC, 32.0 degreesC, 39.0 degreesC, 45.0 degreesC) in aqueous media (mu = 0.10 M, HCl/KCl) to obtain additional kinetic data and to evaluate possible effects of ligand pre-organization for metal ion complexation. The rates are much faster for Ce(TETA)(-) than for Ce(DOTA)(-), indicating the lower thermodynamic stability of the former. In the presence of excess strong acid, 0.1 - 1.0 M HCl, the dissociation reactions follow the rate law: -d[ML]T/dt = (k(d) + k(H)[H+])[ML](T) and -d[ML]T/dt = (k(H)[H+] + k(H2)[H+](2))[ML](T), respectively, where k(d) is acid-independent dissociation reaction rate constant and k(H) and k(H2) are the respective dissociation rate constants for the pathways involving monoprotonated and diprotonated species. The rate activation parameters, DeltaH(not equal), DeltaS(not equal) and DeltaG(not equal), for each dissociation pathway have been obtained and their values are consistent with the proposed mechanisms. In particular, the rate difference between Ce(TETA)(-) and Ce(DOTA)(-) for the monoprotonated complex dissociation pathway is mainly due to difference in DeltaH(H)(not equal). If has been concluded that ligand pre-organization results in more stable complexes and slower complex dissociation rates.
Effects of BF2+ implantation on the oxidation resistance of copper films
(1999-06-01)
Wu, ZC
;
Liu, YL
;
Chen, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work investigates the effects of BF2+ implantation on the oxidation resistance of copper films. The BF2+ ions were implanted into Cu films through a 1000 Angstrom thick screen SiO2 layer. We found that the oxidation resistance of Cu films can be significantly improved by BF2+ implantation at appropriate conditions. In particular, BF2+ implantation at 35 to 40 keV to a dose of 1 - 8 x 10(14) cm(-2) made the Cu films capable of resisting oxidation at temperatures up to 250 degrees C. At these BF2+ implantation energies, boron atoms of peak concentration were projected near the Cu surface; thus the diffusion paths of oxidizing species were efficiently blocked. Implantation at too high energy would result in greater depth of projection, thus a lower concentration of boron at the Cu surface; moreover, it generally leads to increased implantation defects that might serve as diffusion paths for the oxidation species. On the other hand, too high dosage implantation would also have an adverse effect on the capability of oxidation resistance for Cu films owing to the higher density of implantation damage as well as the formation of reactive fluorine compound (CuF2) near the Cu surface. (C) 1999 Elsevier Science S.A. All rights reserved.
Effects of ligand chain length and terminal N-alkylation on the protonation constants and stability constants of some transition metal complexes of linear tetraaza and pentaaza ligands
(1998-12-01)
Chang, CA
;
Shieh, FK
;
Liu, YL
;
Chung, CS
;
生物科技學系
A number of terminal N-alkylated linear tetraaza and pentaaza ligands were prepared. Their ligand protonation constants and some transition and post-transition metal (Ni2+, Cu2+, Zn2+, and Cd2+) complex stability constants were determined by potentiometric titration methods. In general, methylation and ethylation at the terminal nitrogen atoms caused the corresponding ligand nitrogen basicity to increase; however, the corresponding metal complex stabilities were decreased compared to the non-alkylated structural analogs, presumably due to a steric effect.
Effects of ligand chain length and terminal N-alkylation on the protonation constants and stability constants of some transition metal complexes of linear tetraaza and pentaaza ligands
(1998-12-01)
Chang, CA
;
Shieh, FK
;
Liu, YL
;
Chung, CS
;
生物科技學系
A number of terminal N-alkylated linear tetraaza and pentaaza ligands were prepared. Their ligand protonation constants and some transition and post-transition metal (Ni2+, Cu2+, Zn2+, and Cd2+) complex stability constants were determined by potentiometric titration methods. In general, methylation and ethylation at the terminal nitrogen atoms caused the corresponding ligand nitrogen basicity to increase; however, the corresponding metal complex stabilities were decreased compared to the non-alkylated structural analogs, presumably due to a steric effect.
Electrical reliability issues of integrating low-K dielectrics with Cu metallization
(2000)
Wu, ZC
;
Shiung, ZW
;
Wang, CC
;
Fang, KL
;
Wu, RG
Electrical reliability issues of two organic aromatic low-K materials (K = 2.6 similar to 2.8) were investigated. Both materials show acceptable thermal stability and good dielectric barrier property against Cu penetration. C-V curve instability was observed under bias-temperature stress (BTS) for the first time. It can be explained by the model of stress induced dielectric polarization charges. This instability may be an issue of long term stability of circuits.
Electrical reliability issues of integrating thin Ta and TaN barriers with Cu and low-K dielectric
(1999-11-01)
Wu, ZC
;
Wang, CC
;
Wu, RG
;
Liu, YL
;
Chen, PS
This work investigates the integration of very thin sputtered Ta and reactively sputtered TaN barriers with Cu and a low-dielectric-constant (low-K) layer of poly(arylene ether) (PAE-2). It is found that Cu readily penetrates into PAE-2 and degrades its dielectric strength in metal-insulator semiconductor capacitors of Cu/PAE-2/Si structure at temperatures as low as 200 degrees C. Very thin Ta and TaN films of 25 nm thickness sandwiched between Cu and the low-K dielectric served as effective barriers during a 30 min thermal annealing at temperatures up to 400 and 450 degrees C, respectively. We propose a failure mechanism of outgassing induced gaseous stress of PAE-2 under the Ta film to explain its premature barrier degradation. The TaN barrier did not suffer from this gaseous stress problem because of its stronger adhesion to PAE-2 than that of Ta to PAE-2, leading to a better long-term reliability. (C) 1999 The Electrochemical Society. S0013-4651(99)04-046-X. All rights reserved.
Epoxy/polyhedral oligomeric silsesquioxane nanocomposites from octakis(glycidyidimethylsiloxy)octasilsesquioxane and small-molecule curing agents
(2006-06-15)
Liu, YL
;
Chang, GP
;
Hsu, KY
;
Chang, FC
;
應用化學系
Epoxy/polyhedral oligomeric silsesquioxane (POSS) nanocomposites were obtained from octakis(glycidyldimethylsiloxy)octasilsesquioxane (OG) and diglycidyl ether of bisphenol A cured with small-molecule curing agents of diethylphosphite (DEP) and dicyandiamide (DICY). An increase in the POSS contents of the nanocomposites and an improvement in the nanocomposite homogeneity were observed with the use of the small-molecule curing agents. Phosphorus in DEP and nitrogen in DICY also performed synergism with POSS for thermal stability enhancement and flammability improvement in the nanocomposites. The nanocomposites possessing high OG contents exhibited good thermal stability, improved flammability, and high storage moduli. (c) 2006 Wiley Periodicals, Inc.
Ligand preorganization in metal ion complexation: Molecular mechanics/dynamics, kinetics, and laser-excited luminescence studies of trivalent lanthanide complex formation with macrocyclic ligands TETA and DOTA
(2001-07-02)
Chang, CA
;
Liu, YL
;
Chen, CY
;
Chou, XM
;
生物科技學系
The molecular mechanics and dynamics calculations, kinetics, and laser-excited luminescence studies were carried out for trivalent lanthanide (Ln(3+)) complexes of macrocyclic polyaminopolycarboxylate ligands TETA and DOTA (where TETA is 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid and DOTA is 1,4,7,10-tetraazacy-clododecane-1,4,7,10-tetraacetic acid) to further understand the observed thermodynamic, kinetic, and structural properties and to examine how ligand preorganization affects metal ion complexation. Excitation spectroscopy (emission monitored at 614.0 nm) of the F-7(0) - D-5(0)- transition of Eu3+ was used to study the aqueous properties of the Eu3+-TETA system. A stopped-flow spectrophotometric method was used to study the formation kinetics of the aqueous Ce3+-TETA/DOTA systems in the pH range 6.1-6.7. Molecular mechanics calculation results are consistent with the proposed mechanism of Ln(DOTA)- formation, i.e., formation of a. carboxylate O-bonded precursor, followed by metal ion moving into the preformed macrocyclic cavity. For Ln(TETA)- formation, at least two carboxylate O-bonded intermediates have been predicted and Ln(3+) ion assisted reorganization of the TETA ligand is present. The calculated bond distances and overall structures of Ln(DOTA)- and Ln(TETA)were in agreement with the single-crystal and solution NMR structural data. The origin of thr difference in thermodynamic stability of Ln(DOTA)- and Ln(TETA)- complexes and the corresponding formation intermediates is mainly due to the differences in water-occupancy energy (i.e., whether there is an apical coordinated water molecule), the ligand strain energy, and the cation-ligand interaction energy. Kinetic studies revealed that the formation rates of the Ce(TETA)- complex are smaller at lower pH and temperature but become greater at higher pH and temperature, as compared to those of the Ce(DOTA)- complex. This is attributed to the lanthanide ion and both mono- and di-hydroxide ion assisted TETA conformational reorganization and higher kinetic activation parameters. The presence of a di-hydroxide ion assisted intermediate rearrangement pathway could make the Ce(TETA)- complex formation rate faster at higher pH, and the higher activation barrier makes Cr(TETA)complex formation rate slower at lower pH, as compared to those of the Ce(DOTA)- complex.
Passivation of copper films with magnesium doping using recoil ion implantation
(2000-01-10)
Wu, ZC
;
Liu, YL
;
Chen, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work investigates the effects of Ar+ ion implantation through a multilayer structure of SiO2(100 nm)/Mg(20 nm)/Cu/SiO2/Si on the oxidation resistance of Cu films. Experimental results indicate that implantation at 130 keV to a dose of 5 X 10(15) cm(-2) significantly enhances the oxidation resistance at temperatures up to 375 degrees C. At this energy, a small number of Mg atoms are knocked out, leading to formation of an impervious MgO barrier layer on the Cu surface, which effectively suppresses the oxidizing diffusion paths. (C) 2000 Elsevier Science S.A. All rights reserved.