Browsing by Author "Chen, CT"

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Adaptive learning environment to meet pedagogical needs
(2004-11-01)
Su, JM
;
Tseng, SS
;
Chen, CT
;
Tsai, WN
;
資訊工程學系
With the vigorous development of the Internet, e-learning systems have become more and more popular. Currently, to solve the issue of sharing and reusing teaching materials in different e-learning systems, several standard formats, including SCORM, IMS, LOM, AICC etc., have been proposed by international organizations. Among these international standards, the Sharable Content Object Reference Model (SCORM) has become the most popular standard in recent years. In the SCORM standard, Sequencing and Navigation (SN), which is based on the concepts of learning activities, defines the course sequencing behavior, which controls the sequencing, selecting and delivering of the course, and organizes the content into a hierarchical structure, namely, an Activity Tree (AT). For a large-scale learning activity, the Activity Tree will become too complex to manage and reuse, as will its sequencing behavior rules. Moreover, the lack of inter-relations among Activity Trees also makes reusing and integrating them hard. This implies that the scalability and flexibility of an adaptive learning system will be limited. Therefore, how to create, represent and maintain an AT and associated sequencing definitions is our concern. In addition, for a personalized learning environment, how to extend the structure of an AT with Pedagogical Theory has also become an important issue. Therefore, in this paper, we extend and modularize the structure of an AT by applying Pedagogical Theory and the concept of the Object Oriented Methodology, respectively. Thus, we first propose a novel model, the Instructional Activity Model (IAM), which is composed of related AT nodes. Each AT node in IAM is modularized as a learning unit with inter-relations and specific attributes, which can be easily managed, reused, and integrated. We also propose an AT Selection algorithm with a pedagogical strategy for traversing IAM in order to generate dynamic learning content for the learner. IAM with its scalability and flexibility can apply appropriate pedagogical theories to meet specific needs by means of extension scheme. Finally, we propose a systematic approach to fast and easily construction of IAM using traditional course resources.
Aggregation of fuzzy opinions under group decision making
(1996-05-13)
Hsu, HM
;
Chen, CT
;
交大名義發表
;
National Chiao Tung University
In this paper, a method is proposed for aggregating individual fuzzy opinions into a group fuzzy consensus opinion. This paper presents a procedure for aggregating the expert opinions. First, we define the index of consensus of each expert to the other experts using a similarity measure. Then, we aggregate the experts using the index of consensus and the importance of each expert. Finally, a numerical example is given to apply our model.
Anomalous spin polarization and dualistic electronic nature of CrO(2)
(2003-06-01)
Huang, DJ
;
Tjeng, LH
;
Chen, J
;
Chang, CF
;
Wu, WP
Spin-resolved O 1s x-ray absorption measurements on CrO(2) reveal that the spin polarization of the states at the Fermi level approaches 100%, providing direct evidence of the half-metallic nature of CrO(2). The measurements also show the existence of an atomiclike Cr 3d state not far away from the Fermi level with a spin polarization of only 50%, establishing its Mott-Hubbard character. We conclude that CrO(2) has a dualistic electronic nature, in which the states at the Fermi level are bandlike, while those at higher energies are strongly localized of completely different origin and symmetry. The finding of an exceptionally large number of O 2p holes suggests their important role in preventing the strongly correlated CrO(2) from being an insulator.
Anomalous spin polarization and dualistic electronic nature of CrO2
(2003-06-01)
Huang, DJ
;
Tjeng, LH
;
Chen, J
;
Chang, CF
;
Wu, WP
Spin-resolved O 1s x-ray absorption measurements on CrO2 reveal that the spin polarization of the states at the Fermi level approaches 100%, providing direct evidence of the half-metallic nature of CrO2. The measurements also show the existence of an atomiclike Cr 3d state not far away from the Fermi level with a spin polarization of only 50%, establishing its Mott-Hubbard character. We conclude that CrO2 has a dualistic electronic nature, in which the states at the Fermi level are bandlike, while those at higher energies are strongly localized of completely different origin and symmetry. The finding of an exceptionally large number of O 2p holes suggests their important role in preventing the strongly correlated CrO2 from being an insulator.
Charge-orbital ordering and verwey transition in magnetite measured by resonant soft X-ray scattering
(2006-03-10)
Huang, DJ
;
Lin, HJ
;
Okamoto, J
;
Chao, KS
;
Jeng, HT
We report experimental evidence for the charge-orbital ordering in magnetite below the Verwey transition temperature T-V. Measurements of O K-edge resonant x-ray scattering on magnetite reveal that the O 2p states in the vicinity of the Fermi level exhibit a charge-orbital ordering along the c axis with a spatial periodicity of the doubled lattice parameter of the undistorted cubic phase. Such a charge-orbital ordering vanishes abruptly above T-V and exhibits a thermal hysteresis, correlating closely with the Verwey transition in magnetite.
Charge-orbital ordering of magnetite studied by soft resonant X-ray scattering
(2006-05-01)
Chao, KS
;
Huang, DJ
;
Lin, HJ
;
Okamoto, J
;
Hsu, CH
We report direct experimental evidence for the existence of charge and orbital ordering in magnetite. In particular, measurements of oxygen K-edge resonant X-ray scattering on magnetite reveal that the oxygen 2p states in the vicinity of the Fermi level exhibit a charge-orbital ordering with a spatial periodicity of the doubled lattice parameter of the undistorted cubic phase. (c) 2006 Published by Elsevier B.V.
Design of pattern diversity antenna for mobile communications
(1996)
Lee, TS
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Chen, CT
;
Lin, TT
;
電信工程研究所
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Institute of Communications Engineering
Desorption/ionization mass spectrometry on nanocrystalline titania sol-gel-deposited films
(2004)
Chen, CT
;
Chen, YC
;
應用化學系
;
Department of Applied Chemistry
This paper describes a matrix-free method for performing desorption/ionization directly from mesoporous nanocrystalline titanic sol-gel thin films, which have good absorption capacity in the ultraviolet (UV) range and can act as assisting materials during UV matrix-assisted laser desorption/ionization mass spectrometric (MALDI-MS) analysis. A high concentration of citrate buffer was added into this system to provide the proton source and to reduce the presence of alkali cation adducts of the analytes. The analyte signals appear uniformly over the whole sample deposition area. Protonated molecules (MH+ ions) of analytes dominate the titania MALDI mass spectra. Surfactants, peptides, tryptic digest products, and small proteins with molecular weights below ca. 24 000 Da, are observed in the titania MALDI mass spectra. Detection limits for insulin are as low as ca. 2 fmol with mass resolution of ca. 660. Copyright (C) 2004 John Wiley Sons, Ltd.
Dynamic multiple responses by ideal solution analysis
(2004-07-16)
Tong, LI
;
Wang, CH
;
Chen, CC
;
Chen, CT
;
工業工程與管理學系
High technology industry must continuously improve product quality and multiple correlated product quality characteristics must be assessed simultaneously due to product complexity. While many Taguchi method applications have addressed a state system problem, dynamic multi-response problems have seldom been examined. This study presents a novel optimization procedure for dynamic multiple responses based on Taguchi's parameter design. The signal to noise (SN) ratio and system sensitivity are used to assess the performance of each response. Principal component analysis is then performed on the SN values and system sensitivity values to obtain a set of uncorrelated components. The optimization direction for each component is also determined based on the corresponding variation mode chart. Finally, the relative closeness to the ideal solution resulting from the technique for order preference by similarity to ideal solution is determined as an overall performance index for multiple responses. A case study obtained from biological reduction of an ethyl acetoacetate process demonstrates the effectiveness of the proposed procedure. (C) 2003 Elsevier B.V. All rights reserved.
Efficient and bright blue-emitting phosphorescent materials
(2005-10-01)
Yeh, SJ
;
Chen, CT
;
Song, YH
;
Chi, Y
;
Ho, MH
A new type of ancillary ligand for blue-emitting heteroleptic iridium complexes has been successfully developed. New ligands, 3-(trifluoromethyl)-5-( pyridin-2-yl)-1,2,4-triazolate and 5( pyridin-2-yl)-tetrazolate, show stronger blue-shifting power than that of the picolate of Flrpic [ iridium (III) bis(4,6-difluorophenylpyridinato) picolate]. Organic light-emitting diodes (OLEDs) fabricated with a new complex, Flrtaz [ iridium ( III) bis( 4,6-difluorophenylpyridinato)( 5-(pyridine-2-yl)-1,2,4-triazolate) or FlrN4 [(iridium ( III) bis( 4,6-difluorophenylpyridinato)( 5-(pyridin-2-yl)-tetrazolate], as the blue dopant in the host of mCP [ 1,3- bis(9-carbazolyl) benzene], exhibit near-saturated blue electrophosphorescence with Commision Internale de l'Eclairage (CIEx,y) coordinates of (0.14, 0.18) and ( 0.15, 0.24), respectively.
Electromigration in sputtered copper film on plasma-treated hydrogen silsesquioxane dielectric
(2004-04-01)
Chen, CT
;
Chiou, BS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Electromigration (EM) damage is one of the major causes for the failure of interconnects. Plasma treatment, such as dry etching, is frequently employed in the fabrication of multilevel interconnection patterns. This work investigates the hydrogen silsesquioxane (HSQ) and copper integrated systems and the effect of H-2 plasma treatment on the EM of Cu. Hydrogen plasma bombardment induces a rough HSQ surface and results in a coarse morphology of the Cu film deposited on HSQ. The crystallographic texture of Cu is also affected by the plasma treatment. A decrease in the Cu I(111)/I(200) peak ratio is observed for a specimen treated with H-2 plasma. The activation energy for EM in Cu and the EM lifetime of the Cu interconnect decreases with an increased degree of plasma treatment. The activation energies obtained, ranging from 0.76 eV to 0.94 eV, suggest that the electromigration in copper proceeds via an interfacial diffusion path. Possible mechanisms for the effects of plasma treatment are explored. The rough surface and the retarded Cu (111) orientation induced by H-2 plasma bombardment are the major causes for the decrease of activation energy and EM lifetime.
Fe3O4/TiO2 core/shell nanoparticles as affinity probes for the analysis of phosphopeptides using TiO2 surface-assisted laser desorption/ionization mass spectrometry
(2005-09-15)
Chen, CT
;
Chen, YC
;
交大名義發表
;
National Chiao Tung University
Columns packed with microsized titanium dioxide particles have been used effectively as precolumns for enriching phosphopeptides from complex mixtures. Nano-sized titanium dioxide particles have a higher specific surface area and, hence, potentially higher trapping capacities toward phosphopeptides than do microsized particles. Thus, in this study, we employed TiO2-coated magnetic (Fe3O4/TiO2 core/shell) nanoparticles to selectively concentrate phosphopeptides from protein digest products. Because of their magnetic properties, the Fe3O4/TiO2 core/shell nanoparticles that are conjugated to the target peptides can be isolated readily from the sample solutions by employing a magnetic field. In this paper, we also demonstrate that the Fe3O4/TiO2 core/ shell nanoparticles behave as an effective SALDI matrix: our upper detectable mass limit was similar to 24 000 Da, whereas the detection limit for peptides was in the low-femtomole range. That is to say, the target analytes trapped by the Fe3O4/TiO2 nanoparticles can be identified by introducing the particles directly into the mass spectrometer for TiO2-SALDI-MS analysis without the need for any further treatment. For example, elution steps are not necessary when using this approach. In addition, the trapping selectivity of these Fe3O4/TiO2 nanoparticles toward phosphopeptides was quite good. These properties combine to result in the low detection limits. The lowest detectable concentration of phosphopeptides that we analyzed using this approach was 500 pM for a 100-mu L tryptic digest solution of beta-casein; this level is much lower than that which can be obtained using any other currently available method.
Fuzzy credibility relation method for multiple criteria decision-making problems
(1997-01-01)
Hsu, HM
;
Chen, CT
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper dears with the problem of ranking alternatives under multiple criteria. A fuzzy credibility relation (FCR) method is proposed. Owing to vague concepts represented in decision data, in this study the rating of each alternative and the weight of each criterion are expressed in fuzzy numbers. Then we define the concordance, discordance, and support indices. By aggregating the concordance index and support index, a fuzzy credibility relation is calculated to represent the intensity of the preferences of one alternative over another. Finally, according to the fuzzy credibility relation, the ranking order of all alternatives can be determined. A numerical example is solved to highlight the procedure of the FCR method at the end of this paper. (C) Elsevier Science Inc. 1997.
Fuzzy credibility relation method for multiple criteria decision-making problems
(1997-01-01)
Hsu, HM
;
Chen, CT
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper dears with the problem of ranking alternatives under multiple criteria. A fuzzy credibility relation (FCR) method is proposed. Owing to vague concepts represented in decision data, in this study the rating of each alternative and the weight of each criterion are expressed in fuzzy numbers. Then we define the concordance, discordance, and support indices. By aggregating the concordance index and support index, a fuzzy credibility relation is calculated to represent the intensity of the preferences of one alternative over another. Finally, according to the fuzzy credibility relation, the ranking order of all alternatives can be determined. A numerical example is solved to highlight the procedure of the FCR method at the end of this paper. (C) Elsevier Science Inc. 1997.
Improved synthesis of 2,2'-dibromo-9,9'-spirobifluorene and its 2,2'-bisdonor-7,7'-bisacceptor-substituted fluorescent derivatives
(2005-08-18)
Chiang, CL
;
Shu, CF
;
Chen, CT
;
應用化學系
;
Department of Applied Chemistry
[graphics] Pure 2,2'-Dibromo-9,9'-spirobifluorene was synthesized by a method that did not involve troublesome dibromination of 9,9'-spirobifluorene or Sandmeyer reaction of 2,2'-diamino-9,9'-spirobifluorene. A series of donor-acceptor orthogonally substituted 9,9'-spirobifluorene was subsequently prepared showing rich variation of fluorescence in solution and in solid state.
Magnetic circular dichroism in Fe 2p resonant photoemission of magnetite
(2004-02-01)
Chen, J
;
Huang, DJ
;
Tanaka, A
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Chang, CF
;
Chung, SC
Measurements of magnetic circular dichroism in Fe 2p resonant photoemission and calculations based on a full-multiplet cluster model reveal the parameters of the electronic structure of Fe3O4. We obtained on-site Coulomb energy U-dd of 3d electrons, charge-transfer energy Delta which is defined as the energy required to transfer an electron from O 2p to Fe 3d, and the hybridization strength between Fe 3d and O 2p at different Fe ion sites of Fe3O4 by analyzing the data of magnetic circular dichroism. The charge-transfer energy of Fe3+ ions was found to be significantly smaller than that of Fe2+ ions. We determined the energy positions of the low-lying multiplets of each Fe ion site. These energy positions for Fe3+ ion sites are 1.5-2.5 eV higher than those obtained from band-structure calculations. Our calculations also show that the photoemission spectral weight in binding energy bigger than 10 eV is substantial, in contrast to the results of band-structure calculations. Our findings conclude that Fe3O4 is a system with strong electron-electron interactions.
Molecularly imprinted TiO2-matrix-assisted laser desorption/ionization mass spectrometry for selectively detecting alpha-cyclodextrin
(2004-03-01)
Chen, CT
;
Chen, YC
;
應用化學系
;
Department of Applied Chemistry
This study describes a new means to conduct molecular recognition-based analysis using mass spectrometry. Taking advantage of the unique characteristic of the absorption capacity of the TiO2 sol-gel material in the UV region, a TiO2 sol-gel-deposited thin film was employed as the sample substrate to assist in UV laser desorption/ionization of analytes. Sol-gels are polymeric materials that are easy to prepare and modify at low temperatures. Molecularly imprinted TiO2 sol-gels were generated for molecular recognition-based analysis. alpha-Cyclodextrin (CD) was selected as the template molecule and doped into TiO2 in a sol-gel reaction. The molecularly imprinted TiO2 Sol was spin-coated on a glass slide, and appropriate template cavities in the TiO2 sol-gel material were formed after the template molecules were removed. We demonstrate that this modified glass slide can be used to select alpha-CD from a sample solution containing equal amounts of alpha-, beta-, and gamma-CD (50 ppb each, 18 mL); alpha-CD was directly detected from the modified glass slide by matrix-assisted laser desorption/ionization mass spectrometry without the addition of extra matrix. This approach provides a new detection method for molecular recognition-based analysis.
New dopant and host materials for blue-light-emitting phosphorescent organic electroluminescent devices
(2005-02-10)
Yeh, SJ
;
Wu, MF
;
Chen, CT
;
Song, YH
;
Chi, Y
Efficient organic light-emitting diodes (OLEDs) incorporating Ir-III bis(4,6-difluorophenylpyridinato)3-(trifluoromethyl)-5-(pyridin-2-yl)-1,2,4-triazolate (FIrtaz) and Ir-III bis(4,6-difluorophenylpyridinato)-5- (pyridin-2-yl)-1H-tetrazolate (FIrN4) demonstrate higher-purity blue-light emission than the long-known Ir-III bis(4,6-difluorophenylpyridinato)-picolate (FIrpic) phosphorophore. New host materials with higher glass-transition temperatures were also found to enhance the OLED performance.
Orbital magnetic moments of oxygen and chromium in CrO2
(2002-11-01)
Huang, DJ
;
Jeng, HT
;
Chang, CF
;
Guo, GY
;
Chen, J
With measurements of the magnetic circular dichroism and band-structure calculations in the local spin density approximation (LSDA+U) approach, we revealed that the orbital moment of O in CrO2 is ferromagnetically coupled to that of Cr, whereas the spin moment of O is antiferromagnetically coupled to that of Cr. Spin and orbital magnetic moments of Cr and O are enhanced as Coulomb interaction energy U increases. Comparing the magnetic circular diachromism data with the LSDA+U calculations, we conclude that it is essential to include the on-site Coulomb energy for adequately describing the orbital magnetic moments of CrO2.
Orbital moments of CrO2 and Fe3O4 studied by MCD in soft X-ray absorption
(2004-07-01)
Huang, DJ
;
Chang, CF
;
Chen, J
;
Lin, HJ
;
Chung, SC
We present studies of orbital magnetic moments of CrO2 and Fe3O4 by measuring magnetic circular dichroism (MCD) in soft X-ray absorption. The results show that Fe3O4 exhibits large orbital moments, as a consequence of the strong Coulomb interactions of Fe 3d electrons. In contrast, orbital moments of Cr in CrO2 are nearly quenched, revealing that Cr 3d electrons are strongly hybridized with O 2p electrons and more delocalized as compared with those of Fe in Fe3O4. Comparing the MCD data with the band structure calculations based on local spin density approximation with on-site Coulomb energy U taken into account, we conclude that to include the on-site Coulomb interactions of 3d electrons is essential for adequately describing the electronic structure of CrO2 and Fe3O4. (C) 2004 Elsevier B.V. All rights reserved.