Browsing by Author "Chen, JC"

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Antiresonant reflecting optical waveguide surface plasmon resonance sensors
(2001)
Huang, YT
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Chang, WZ
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Hsu, SH
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Chen, CH
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Chen, JC
An ARROW-B (antiresonant reflecting optical wavegnide, type B) surface plasmon resonance (SPR) sensor operating in aqueous environment is proposed. The characteristics, design, and optimization of the Au-coated ARROW-B SPR sensor are discussed. The operating range of the sensor can be shifted by adding a dielectric overlay. The detectable changes of the refractive index down to the order of 10(-5) can be achieved. The design of an ARROW SPR sensor on Si substrates for detecting hydrogen molecules with palladium as the metal film will also be discussed.
Design of knockout concentrators
(1998-06-01)
Lin, YS
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Shung, CB
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Chen, JC
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The knockout switch architecture has been found attractive for large-scale switch implementations because of its satisfactory cell loss performance, with constant output buffer speed-up independent of switch dimension. The per port hardware complexity of a knockout concentrator, however, does grow linearly with the switch dimension. In the paper, several approaches are investigated to reduce the complexity of the knockout while retaining the cell loss performance. A bufferless hierarchical concentrator architecture with reduced hardware complexity is derived. The concentrator complexity can be further reduced by introducing buffers in the concentrator, and the trade-off is analysed. Furthermore, output grouping may be applied in the buffered hierarchical concentrator to reduce the per port complexity. Two large-scale switch design examples are derived using the proposed design approaches, producing a complexity reduction ranging from 1.2% to 89.7%.
Equivalence checking of integer multipliers
(2001)
Chen, JC
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Chen, YA
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資訊工程學系
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Department of Computer Science
In this paper, we address on equivalence checking of integer multipliers, especially for the multipliers without structure similarity. Our approach is based on Hamaguchi's backward substitution method with the following improvements: (1) automatic identification of components to form proper cut points and thus dramatically improve the backward substitution process, (2) a layered-backward substitution algorithm to reduce the number of substitutions, and (3) Multiplicative Power Hybrid Decision Diagrams(*PHDDs) as our word-level representation rather than *BMD in Hamaguchi's approach. Experimental results show that our approach can efficiently check the equivalence of two integer multipliers. To verify the equivalence of a 32 x 32 array multiplier versus a 32 x 32 Wallace tree multiplier, our approach takes about 57 CPU seconds using ii Mbytes, while Stanion's approach took 21027 seconds using 130 MBytes. We also show that the complexity of our approach is upper bounded by O(n(4)), where n is the word size, but our experimental results show that the complexity of our approach grows cubically O(n(3)).
Facilitation of sensory and motor recovery by thermal intervention for the hemiplegic upper limb in acute stroke patients - A single-blind Randomized clinical trial
(2005-12-01)
Chen, JC
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Liang, CC
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Shaw, FZ
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生物科技學系
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Department of Biological Science and Technology
Background and Purpose - Thermal stimulation (TS) is commonly used in orthopedic rehabilitation, but the role of TS in the facilitation of sensorimotor recovery in hemiplegic patients remains unknown. This study addressed the issue of TS intervention in the facilitation of functional outcomes. Methods - Forty-six stroke survivors were randomly assigned to standard rehabilitation treatment and standard treatment plus TS (30 minutes daily for 6 weeks). Twenty-nine patients completed the experiment. Six measures, including Brunnstrom stage, modified motor assessment scale, grasping strength, angles of wrist extension and flexion, sensation by monofilament, and muscle tone by modified Ashworth scale, were performed weekly to evaluate sensory and motor functional outcomes. Results - The performance of Brunnstrom stage and wrist extension and sensation were improved significantly after TS intervention. Recovery rates of 6 measures after TS were significantly higher than those of the control, except for grasping. Similar muscle tones were found in both groups. Conclusion - TS on the paretic hand significantly enhances the recovery of several aspects of sensory and motor functions in hemiplegic stroke patients.
Influence of N2O plasma treatment on microstructure and thermal stability of WNx barriers for Cu interconnection
(2004-05-01)
Tsai, KC
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Wu, WF
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Chen, JC
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Pan, TJ
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Chao, CG
Thermal stabilities of Cu-contacted n(+)-p junctions with tungsten nitride (WNx) diffusion barriers deposited at various nitrogen flow ratios are investigated. N2O plasma treatment is applied to improve thermal stability and barrier performance of WNx film. Sheet resistance Of Cu/N2O plasma-treated WNx/Si is fairly stable even after annealing at 750degreesC for 30 min. Moreover, N2O plasma treatment enables the Cu/WNx/n(+)-p junction-diodes to sustain thermal annealing at 600 degreesC without electrical degradation. Auger electron spectroscopy depth profiles show that Cu diffusion through the N2O plasma-treated WNx barrier is extremely limited, even after annealing at 675 degreesC. Analyses of transmission electron microscopy and x-ray photoemission spectroscopy show that nitridation and oxidation on the WNx barrier occur and an amorphous layer is formed after N2O plasma treatment. (C) 2004 American Vacuum Society.
Mismatch analysis of TAB-on-Glass connection with ACF
(2000)
Hou, WF
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Kam, TY
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Hsieh, A
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Chen, JC
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Chang, SM
Mismatch between outer lead bonds (OLBs) of a tape automated bonding (TAB) and a glass panel during fabrication is studied using the finite element method. A two-dimensional finite element model for the TAB-on Glass (TOG) connector is presented for determining the deformation of the connector. The deformation of the TOG connector induced by residual thermal stresses are determined via a two-stage approach. At the first stage, the TOG connector is under heat and pressure. The anisotropic conductive film (ACF) in-between the TAB and glass panel is assumed to be in a melting condition so that both TAB and glass panel can expand freely. At the second stage, the connector is cooled down to room temperature and the ACF becomes solidified. The deformations of the connector at the two stages are determined in the finite element analysis in which the temperature dependence of material properties is considered. Effects of particular parameters on the mismatch between the OLBs are studied by means of a number of numerical examples. A method for compensation design of the lead locations of the OLBs is proposed. It has been shown that the compensation design can produce results that will avoid the occurrence of unwanted mismatch.
Novel multilayered Ti/TiN diffusion barrier for Al metallization
(2005-08-01)
Wu, WF
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Tsai, KC
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Chao, CG
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Chen, JC
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Ou, KL
A novel, multilayered Ti/TiN diffusion barrier is proposed and successfully applied for Al metallization. The multilayered Ti/TiN structure is effective in enhancing the barrier properties since the very thin Ti layer inserted into titanium nitride (TiN) barrier can cause disruption of the TiN columnar growth and reduction of open grain boundaries resulting in retarded interdiffusion between metal and silicon. Multilayered Ti/TiN films are deposited sequentially by sputtering without breaking vacuum. It is found that TiN grain boundaries are discontinuous when a Ti layer is inserted into TiN. Multilayered Ti/TiN has a better barrier performance than single-layer TiN in Al metallization. However, the barrier performance is related to the number and thickness of the inserted Ti layers, because increasing titanium will enhance chemical reactions between Al and barrier layers, and produce more titanium-aluminum compounds. The total thickness of introduced Ti layers should be reduced to improve barrier performance.
Numerical and experimental analysis of Cu diffusion in plasma-treated tungsten barrier
(2005)
Tsai, KC
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Wu, WF
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Chen, JC
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Pan, TJ
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Chao, CG
This work investigates Cu diffusion in sputtered and N2O plasma-treated W films. N2O plasma-treated W barrier has a nanostructured surface layer and shows high thermal stability and the best barrier properties. Also investigated herein are the lattice and grain boundary diffusivities extracted from the Cu penetration depth profiles using the Whipple analysis of grain boundary diffusion and Fick's second law of diffusion. Analysis indicates that the diffusion models correlate well with experimental results. (C) 2004 The Electrochemical Society.
Numerical and experimental study of internal flow field for a carbon fiber tow pneumatic spreader
(2001-04-01)
Chen, JC
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Chao, CG
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材料科學與工程學系
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Department of Materials Science and Engineering
In this study, a three-dimensional (3-D) mathematical model of a fiber pneumatic spreader was successfully developed in the physical phenomena of the internal flow field by a far-field treatment at boundary conditions. The 3-D numerical analysis was carried out on incompressible fluid flows in the pneumatic spreader by using finite volume method combined with the k-epsilon turbulence model which solves Reynolds-averaged Naiver-Stokes equations. Characteristics of the flow field in the spreader at different service conditions are investigated by velocity and pressure distributions. Comparisons of numerical results with measured velocity and pressure distributions were made to determine the accuracy of the employed method. A good agreement was found in both qualitative and quantitative analysis. Fibers were spread on 1:1-scale model of the pneumatic spreader at various fiber transporting rates and air flow rates. Photography techniques were simultaneously used to record the procedures of fibers spread. The carbon fiber tow was easily spread out at service conditions. The performance was better than prior studies in one-dimensional orifice formulation. The results revealed details of the fiber spreading processes. Agreement among those results validated the assumptions inherent to the computational calculation and gave confidence to more complex geometries as well as flow fields. In other words, the use of numerical analysis in the internal flow field was useful for the fiber pneumatic spreader design.
Numerical simulation and experimental investigation for design of a carbon fiber tow pneumatic spreading system
(2005-10-01)
Chen, JC
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Chao, CG
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材料科學與工程學系
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Department of Materials Science and Engineering
The work successfully designs a high efficient carbon fiber pneumatic spreading system. The internal flow field of the fiber pneumatic spreader was first simulated by solving Reynolds-averaged Naiver Stokes equations, and the characteristics of the flow pattern in the spreader under various operation conditions were analyzed in terms of the mass flow rate and the velocity distributions. Comparisons of numerical results with measured velocity and pressure distributions were made to determine the accuracy of the employed method. A good agreement was found in both qualitative and quantitative analysis. A new variable, spreading evenness, was defined to specify the dispersing extent of fibers in a carbon fiber tow during the fiber pneumatic spreading process. By the spreading evenness, a quantitative comparison of a spread carbon fiber tow can be made and the optimum condition can be easily obtained at fiber spreading experiments. The dispersing mechanism of a carbon fiber tow was comprehensive by the computational modeling and the spreading experiment. The performance of the fiber tow pneumatic spreader system was better than prior studies, and the use of numerical analysis combined with the fiber spreading experiment was useful for the development of the fiber pneumatic spreading system. (C) 2005 Elsevier Ltd. All rights reserved.
Random-coincidence corrections using iterative reconstruction for PET images
(2000)
Chen, JC
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Liu, RS
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Tu, KY
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Lu, HHS
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Chen, TB
Iterative reconstruction (IR) algorithms can reduce artifacts caused by filtered backprojection (FBP) or convolution backprojection (CBP). Recently, the computational effects required for IR of positron emission tomography (PET) studies have been reduced to make it practically appealing. We have made an implementation of the improved Maximum Likelihood-Expectation Maximization (ML-EM) algorithm. The transition matrix was generated based on the geometry of the instrument. Phantoms of 6 line sources and 19 line sources were used to test our accelerated ML-EM algorithms against the FBP method. The singles were used to calculate the random coincidence rates by a well known formula and were compared to the randoms obtained by another geometric method. We also designed a new model using two line sources to determine the ratio of random events to true events. The artifacts near those line sources were eliminated with the ML-EM method. With decay correction, the RC events were uniformly distributed in whole field after 10 iterations. The ML-EM reconstructed images are superior to those obtained with FBP. The patterns of randoms provide insightful information for random correction, which the hardware correction by the delay window can not provide. This information is particular valuable when the delay window correction is not available in the old fashion PET scanner.