Browsing by Author "Lee, Ching-Hung"

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A Fuzzy Neural Network Based Adaptive Predictor with P-Controller Compensation for Lossless Compression of Images
(2009)
Lee, Ching-Hung
;
Kau, Lih-Jen
;
Lin, Yuan-Pei
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電控工程研究所
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Institute of Electrical and Control Engineering
Predictively encoded techniques are commonly used for lossless compression of images for its effectiveness of removing statistical redundancy between pixels. However, there can be large prediction errors for pixels around boundaries. In this paper, we introduce techniques commonly used in control systems to enhance the coding efficiency of predictive coding. Actually, the predictive coding system behaves just like a multi-input single-output system with the predictor itself can be taken as the system model. When compared with the purpose of a control system, which is to follow the system command as precisely as possible, we find the objective of both systems are the same. Moreover, an edge or a boundary among image pixels can be regarded as a step command in control systems. These observations lead to the idea of using control technologies to improve prediction result for pixels around boundaries. To realize this idea, we use an adaptive Takagi-Sugeno fuzzy neural network (TS-FNN) as the predictor. Furthermore, the widely used proportional controller in control system is implemented implicitly in the consequent part of the network so that the prediction error can be further compensated for pixels around boundaries. We find in experiments that the proposed approach can have a very good prediction result even without using any online training area for network adaptation process. This makes the proposed system more feasible under limited resources. Finally, comparisons to existing state-of-theart lossless predictors and coders will be given to highlight the advantages of the proposed novel approach.
An approach to estimate domain of attraction for nonlinear control systems
(2006)
Liaw, Der-Cherng
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Lee, Ching-Hung
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電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper we present the results of estimation of domain of attraction for nonlinear control systems. The theoretical results of [[9]] is modified and a computational methods to enlarge the domain of attraction for nonlinear control systems is proposed By the way, we have computational algorithms to estimate the attraction region for locally stable nonlinear systems in uncontrolled version. It is achieved by the construction of Lyapunov function for the nonlinear systems. Numerical results are given to demonstrate the applications.
Functional Investigation of Transmembrane Helix 3 in H+-Translocating Pyrophosphatase
(2013-12-01)
Lee, Ching-Hung
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Chen, Yen-Wei
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Huang, Yun-Tzu
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Pan, Yih-Jiuan
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Lee, Chien-Hsien
H+-translocating pyrophosphatase (H+-PPase, EC 3.6.1.1) plays an important role in acidifying vacuoles by transporting protons across membranes at the expense of pyrophosphate (PPi) hydrolysis. Vigna radiata H+-PPase (VrH(+)-PPase) contains 16 transmembrane helices (TMs). The hydrophobicity of TM3 is relatively lower than that of most other TMs, and the amino acids in this TM are highly conserved in plants. Furthermore, TM5 and -6, which are the core TMs involving in H+-PPase functions, are near TM3. It is thus proposed that TM3 is associated with H+-PPase activity. To address this possibility, site-directed mutagenesis was applied in this investigation to determine the role of TM3 in VrH(+)-PPase. Upon alanine/serine substitution, T138 and S142, whose side chains face toward the center TMs, were found to be involved in efficient proton transport. G149/S153 and G160/A164 pairs at the crucial termini of the two GxxxG-like motifs are indispensable in maintaining enzymatic activities and conformational stability. Moreover, stability in the vicinity surrounding G149 is pivotal for efficient expression. S153, M161 and A164 are critical for the K+-mediated stimulation of H+-PPase. Taken together, our results demonstrate that TM3 plays essential roles in PPi hydrolysis, proton transport, expression, and K+ stimulation of H+-PPase.
Single Molecule Take-and-Place Technique for Positioning a Membrane Protein on a Lipid Bilayer
(2015-09-10)
Liu, Tseng-Huang
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Huang, Yun-Tzu
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Cheng, Hui-Wen
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Chen, Yen-Wei
;
Lee, Ching-Hung
Manipulating a single protein molecule on liposomes or planar lipid bilayers is a useful technique for studying membrane-bound proteins, receptors, or ion transporters and for delicate applications including biosensor chips, drug screening, and clinical diagnoses. However, several key breakthroughs are required for success through difficult techniques such as single protein take-and-place with reasonable spatiotemporal control. In this report, a novel method was established for placing a single transmembrane protein onto a patterned lipid bilayer. A surface-functionalized 1.8 nm gold nanoparticle was first engineered at the tip of an atomic force microscope. A single transmembrane protein, H+-translocating pyrophosphatase with six-histidine residues tag, was then picked up using such a microscopy tip where its nanoparticle was modified by nickel-nitrilotriacetic acid. Two-step fluorescence bleaching observation and quantum dot blinking analysis subsequently verified successful manipulation of a single functional protein on a lipid membrane in a predetermined manner. Furthermore, the enzymatic activity from the single H+-translocating pyrophosphatase was determined, demonstrating that membrane proteins retain their functions on the lipid bilayer through a single-molecule take-and-place technique. This innovative technique overcomes current limitations and provides a single biomolecule nanomanipulation system for versatile studies of membrane-bound proteins.