Browsing by Author "Lee, WS"

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A repetitive learning method based on sliding mode for robot control
(2000-03-01)
Liu, TS
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Lee, WS
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機械工程學系
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Department of Mechanical Engineering
In order to make a robot precisely track desired periodic trajectories, this work proposes a sliding mode based repetitive learning control method, which incorporates characteristics of sliding mode control into repetitive learning control. The learning algorithm not only utilizes shape functions to approximate influence functions in integral transforms, but also estimates inverse dynamics functions based on integral transforms. It learns at each sampling instant the desired input joint torques without prior knowledge of the robot dynamics. To carry out sliding mode control, a reaching law method is employed, which is robust against model uncertainties and external disturbances. Experiments are performed to validate the proposed method.
Caspase activation of mammalian Sterile 20-like kinase 3 (Mst3) - Nuclear translocation and induction of apoptosis
(2002-09-13)
Huang, CYF
;
Wu, YM
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Hsu, CY
;
Lee, WS
;
Lai, MD
Mammalian Sterile 20-like kinase 3 (Mst3), the physiological functions of which are unknown, is a member of the germinal center kinase-III family. It contains a conserved kinase domain at its NH2 terminus, whereas there is a regulatory domain at its COOH terminus. In this study we demonstrate that endogenous Mst3 is specifically cleaved when Jurkat cells were treated with anti-Fas antibody or staurosporine and that this cleavage is inhibited by the caspase inhibitor, Ac-DEVD-CHO. Using apoptotic Jurkat cell extracts and recombinant caspases, we mapped the caspase cleavage site, AETD(313), which is at the junction of the NH2-terminal kinase domain and the COOH-terminal regulatory domain. Caspase-mediated cleavage of. Mst3 activates its intrinsic kinase activity, suggesting that the COOH-terminal domain of Mst3 negatively regulates the kinase domain. Furthermore, proteolytic removal of the Mst3 COOH-terminal domain by caspases promotes nuclear translocation. Ectopic expression of either wild-type or COOH-terminal truncated Mst3 in cells results in DNA fragmentation and morphological changes characteristic of apoptosis. By contrast, no such changes were exhibited for catalytically inactive Mst3, implicating the involvement of Mst3 kinase activity for mediation of these effects. Collectively, these results support the notion that caspase-mediated proteolytic activation of Mst3 contributes to apoptosis.
Identification and characterization of the nuclear import and export signals of the mammalian Ste20-like protein kinase 3
(2004-08-13)
Lee, WS
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Hsu, CY
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Wang, PL
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Huang, CYF
;
Chang, CH
Mst3, a human Ste20-like protein kinase, has been recently demonstrated to undergo a caspase-mediated cleavage during apoptosis. The proteolytic cleavage of the C-terminus of Mst3 caused nuclear translocation of its kinase domain. This work provides evidence that Mst3 may contain a bipartite-like nuclear localization sequence (NLS) at the C-terminus of its kinase domain (residues 278-292). The removal of NLS from the kinase domain of Mst3 led to the cytoplasmic accumulation of EGFP-Mst3 (Delta277). The presence of nuclear exporting signals in the Mst3 was also demonstrated by leptomycin B-treatment and serial deletion of the C-terminal regulatory domain of Mst3. A nuclear export signal was also postulated to be in the regions of amino acids 335-386. In conclusion, Mst3 contains both NLS and NES signals, which may cooperate to control the subcellular distribution of Mst3. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Nonlinear diffusion-induced stresses in a long bar of square cross section
(1999-01-01)
Hwang, CC
;
Lin, SP
;
Chu, HS
;
Lee, WS
;
機械工程學系
This paper is to investigate the nonlinear effect of the self-induced electric field on the diffusion-induced stresses in a long bar. We first approximate the nonlinear concentration-dependent diffusivity asa series of third-degree polynomials by the least-squares curve-fitting techniques, and then calculate the distributions of concentration by the Galerkin method. Afterwards, the diffusion-induced stresses inside the bar are determined analytically by introducing the Goodier displacement potential and Airy stress function. It is found that the nonlinear self-induced electric fields can depress both the concentration gradient and the maximum diffusion-induced stresses apparently, and these effects are more significant at short times than at long times. (C) 1998 Elsevier Science Ltd. All rights reserved.
Novel post CMP cleaning using buffered HF solution and ozone water
(2003-06-30)
Yeh, CF
;
Hsiao, CW
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Lee, WS
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Post chemical mechanical polishing (CMP) cleaning is a key process for copper (Cu) CMP in dual damascene interconnection technology. During the post CMP cleaning, it is an important issue to minimize organic and Cu contamination residues on the dielectric surface. This study proposed a novel post CMP cleaning using HAL buffer hydrofluoric (BHF) solution and ozone (O-3) water cleaning. The performance of the proposed cleaning technology was investigated and compared to conventional citric solution cleaning, which is currently used in post Cu CMP cleaning. From roughness, contamination residues and electrical characteristics, the proposed cleaning technology showed better performance than citric solution cleaning did. This excellent cleaning performance is attributed to the surface etching and contamination elimination effect of HAL BHF solution and O-3 water. Based on the experimental results, the proposed cleaning technology is feasible and superior to the conventional post CMP cleaning. (C) 2003 Elsevier Science B.V. All rights reserved.
Pressure boundary treatment in internal gas flows at subsonic speed using the DSMC method
(2001)
Wu, JS
;
Lee, WS
;
Lee, F
;
Wong, SC
;
機械工程學系
Two numerical procedures in the Direct Simulation Monte Carlo method, applying particle flux conservation at inflow/outflow pressure boundaries, are developed to treat the two most important boundary conditions encountered in micromechanical and vacuum devices involving internal gaseous flows. The first one is for both specified pressures at inlet and exit; while the second one is for specified mass flow rate and exit pressure. Both numerical procedures have been tested on short and long micro-channels in the slip and transitional regimes. Excellent agreement has been found between the current results and the previous reported numerical results as well as the experimental data for the first type of boundary conditions. Finally, the first type boundary condition is applied to compute the conductance of flow through a circular pipe to demonstrate its application in vacuum technology. Results compare well with previous experimental data by Knudsen (1909).