Browsing by Author "Ko, MT"

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A new LDA-based face recognition system which can solve the small sample size problem
(2000-10-01)
Chen, LF
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Liao, HYM
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Ko, MT
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Lin, JC
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Yu, GJ
A new LDA-based face recognition system is presented in this papal. Linear discriminant analysis (LDA) is one of the most popular linear projection techniques for feature extraction. The major drawback of applying LDA is that it may encounter the small sample size problem. In this paper, we propose a new LDA-based technique which can solve the small sample size problem. We also prove that the most expressive vectors derived ill the null space of the within-class scatter matrix using principal component analysis (PCA) are equal to the optimal discriminant vectors derived in the: original space using LDA. The experimental results show that the new LDA process improves the performance of a face recognition system significantly. (C) 2000 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.
A simple self-collision avoidance for cloth animation
(1998-01-01)
Liu, JD
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Ko, MT
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Chang, RC
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資訊工程學系
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Department of Computer Science
This paper discusses the self-collision avoidance problem in simulating the dynamic behavior of deformable cloth. It is not an easy task to simulate realistically the response of cloth in various types of complicated self-collisions. In this paper, the bounding box technique in addition to ordinary pre-checking for collision detection is used to avoid self-collision. Instead of avoiding self-collision of cloth triangles, we relax to avoid the collision of the bounding boxes of cloth triangles. Some constraints are enforced on the vertices of the cloth triangles to prevent their bounding boxes from penetrating in the direction of collision. The experimental results show that the relaxed self-collision avoidance method can create realistic cloth behavior and wrinkling formation processes. Since the types of interaction between bounding boxes are simple, our method is simple but robust in avoiding self-collisions. (C) 1998 Elsevier Science Ltd. All rights reserved.
Amino acid coupling patterns in thermophilic proteins
(2005-04-01)
Liang, HK
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Huang, CM
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Ko, MT
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Hwang, JK
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生物資訊及系統生物研究所
Structural analysis is useful in elucidating structural features responsible for enhanced thermal stability of proteins. However, due to the rapid increase of sequenced genomic data, there are far more protein sequences than the corresponding three-dimensional (3D) structures. The usual sequence-based amino acid composition analysis provides useful but simplified clues about the amino acid types related to thermal stability of proteins. In this work, we developed a statistical approach to identify the significant amino acid coupling sequence patterns in thermophilic proteins. The amino acid coupling sequence pattern is defined as any 2 types of amino acids separated by I or more amino acids. Using this approach, we construct the p profiles for the coupling patterns. The p value gives a measure of the relative occurrence of a coupling pattern in thermophiles compared with mesophiles. We found that thermophiles and mesophiles exhibit significant bias in their amino acid coupling patterns. We showed that such bias is mainly due to temperature adaptation instead of species or GC content variations. Though no single outstanding coupling pattern can adequately account for protein thermostability, we can use a group of amino acid coupling patterns having strong statistical significance (p values < 10(-7)) to distinguish between thermophilic and mesophilic proteins. We found a good correlation between the optimal growth temperatures of the genomes and the occurrences of the coupling patterns (the correlation coefficient is 0.89). Furthermore, we can separate the thermophilic proteins from their mesophilic orthologs using the amino acid coupling patterns. These results may be useful in the study of the enhanced stability of proteins from thermophiles - especially when structural information is scarce. (C) 2005 Wiley-Liss, Inc.
Collision avoidance in cloth animation
(1996)
Liu, JD
;
Ko, MT
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Chang, RC
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資訊工程學系
;
Department of Computer Science
For cloth modeling and animation, we use a physically based model to simulate the dynamic formation of folds, pleats, and wrinkles and the final static appearance of cloth draped over a rigid object. To simulate the behavior of the cloth and its final static appearance on the model, we propose a new collision and self-collision avoidance method to prevent penetration between the cloth and rigid objects and between parts of the cloth. At each time step, we enforce constraints over those grid points about to penetrate other objects. Our method is easier and more robust than conventional methods at representing interaction between the cloth and various objects.
Experience in designing a using TCP as transport protocol VOD system over a dedicated network
(1998-11-01)
Lu, DJ
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Wang, YC
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Ho, JM
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Chen, MC
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Ko, MT
In this paper we address the problem of designing a TCP[11] and IP[10] (TCP/IP for short) based video on demand (VOD for short) system over a dedicated network based on standard internet protocols, ie., Transmission Control Protocol (TCP for short, IETF RFC 793[11]) and Internet Protocol (IP for short, IETF RFC 791[10]). TCP and IP are usually refered together as TCP/IP. Despite of the general belief that TCP/IP is not suitable for real-time multimedia applications, after testing in laboratory environment for about one year we are confident in announcing that our prototype is both efficient and reliable. This success depends on several important factors. First of all, the system operates on a dedicated network in which there exists no other traffic except a light of background traffic generated by the Ether Switch the major network component used by our prototype. Second system overhead due to the VOD server and the network adaptor card is minimized Third, we maximize disk bandwidth by implementing a proprietary disk file system. Our experiment shows that it requires only about 330 KBytes at the client buffer to smooth packet delay jitters. In our experimental environment, due to resource limitations, up to 40 clients had been tested successfully. By looking at network bandwidth and CPU utilization, we estimate that a single VOD sewer should be able to handle more than 40 interactive clients playing MPEG-1 system streams simultaneously.
Relationship between local structural entropy and protein thermostability
(2004-12-01)
Chan, CH
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Liang, HK
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Hsiao, NW
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Ko, MT
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Lyu, PC
We developed a technique to compute structural entropy directly from protein sequences. We explored the possibility of using structural entropy to identify residues involved in thermal stabilization of various protein families. Examples include methanococcal adenylate kinase, Ribonuclease HI and holocytochrome c(551). Our results show that the positions of the largest structural entropy differences between wild type and mutant usually coincide with the residues relevant to thermostability. We also observed a good linear relationship between the average structural entropy and the melting temperatures for adenylate kinase and its chimeric constructs. To validate this linear relationship, we compiled a large dataset comprised of 1153 sequences and found that most protein families still display similar linear relationships. Our results suggest that the multitude of interactions involved in thermal stabilization may be generalized into the tendency of proteins to maintain local structural conservation. The linear relationship between structural entropy and protein thermostability should be useful in the study of protein thermal stabilization. (C) 2004 Wiley-Liss, Inc.