Browsing by Author "LEE, CH"

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A FAST SEARCH ALGORITHM FOR VECTOR QUANTIZATION USING MEAN PYRAMIDS OF CODEWORDS
(1995-02-01)
LEE, CH
;
CHEN, LH
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
One of the most serious problems for vector quantization, especially for high dimensional vectors, is the high computational complexity of searching for the closest codeword in the codebook design and encoding phases. Although quantizing high dimensional vectors rather than low dimensional vectors results in better performance, the computation time needed for vector quantization grows exponentially with the vector dimension. This makes high dimensional vectors unsuitable for vector quantization. To overcome this problem, a fast search algorithm, under the assumption that the distortion is measured by the squared Euclidean distance, will be proposed. Using the mean pyramids of codewords, the algorithm can reject many codewords that are impossible matches and hence save a great deal of computation time. The algorithm is efficient for high dimensional codeword searches. Experimental results confirm the effectiveness of the proposed method.
A past search algorithm for vector quantization using means and variances of codewords
(1995)
LEE, CH
;
CHEN, LH
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資訊工程學系
;
Department of Computer Science
A TRANSIENT NATURAL-CONVECTION IN AN ANNULAR ENCLOSURE
(1991-05-01)
FU, WS
;
JOU, YH
;
LEE, CH
;
交大名義發表
;
機械工程學系
A transient natural convection in an annular enclosure is investigated numerically. The upper and lower walls are adiabatic, the outer wall is maintained at a low temperature and the temperature of the inner wall is changed to a high value abruptly. During the computing process, the numerical method of SIMPLE-R with power law scheme is adopted to solve the axially-symmetric governing equations of the continuity, momentum and energy. The Rayleigh number of 10(4) and 10(6) are considered, respectively. Since the area of the annular cross section enlarges with the increasing of the radius, the phenomena occurring in the annular enclosure are different from those occurring in the rectangular enclosure. In addition, the results show that in the initial region the variations of the total Nusselt of the inner wall rebounds under Rayleigh number of 10(6) case and does not fluctuate under Rayleigh number of 10(4) case, which are similar to those of the rectangular enclosure.
ACTIVITY-COEFFICIENTS OF ELECTRONS AND HOLES IN DEGENERATE SEMICONDUCTORS WITH NONUNIFORM COMPOSITION
(1994-03-01)
CHANG, KM
;
YEH, TH
;
WANG, SW
;
LEE, CH
;
電子工程學系及電子研究所
A new simple, general and rigorous analytic expression for the equilibrium activity coefficients of electrons and holes in degenerate semiconductors with nonuniform composition is presented. These activity coefficients are functions of the carrier degeneracy (Fermi-Dirac statistics), the band gap, the electron affinity and the density of states which vary with position. The calculation of carrier activity coefficients requires the selection of chemical potential and electrostatic potential references. The choice of these reference states is addressed. The relationships between purely thermodynamic quantities and parameters of the band theory are also presented. Emphasis is also placed on formulating an equation in a simple, Boltzmann-like form in which the nonideal behavior is described by two parameters, the effective band-gap shrinkage, DELTAE(g), and the effective asymmetry factor, A. In this form the working equations for the carrier densities and activity coefficients are convenient for use in computer-aided analysis and design. The approach presented here allows convenient treatment of nonuniform degenerate semiconductors in a manner that is consistent with thermodynamics as well as with the Poisson-Boltzmann equation for the electrostatic potential.
BACKPROPAGATION LEARNS MARR OPERATOR
(1993-11-01)
JOSHI, A
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LEE, CH
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資訊工程學系
;
Department of Computer Science
This paper describes a neural network model of the retinal responses to stimuli whose architecture is inspired by neurophysiological data. Suitable assumptions are identified which enable the development of a simple model for an individual X-type ganglion cell using backpropagation. This is then used to make a model of retinal processing. We present here our model of the individual ganglion cells and the underlying assumptions. We show that backpropagation leads to a model which is similar to the mathematical descriptions of retinal processing advanced by Marr. We present the results obtained when our model is used to simulate the effect of retinal processing on images. Empirical results about the speedups obtained when this model is implemented on parallel architectures are also reported.
COMPUTING 3-DIMENSIONAL MOTION PARAMETERS - A HYPOTHESIS-TESTING APPROACH
(1993-04-01)
LEE, CH
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
;
Department of Computer Science
Despite great advances in the analysis of motion problems, implementing or searching for correct and robust algorithms is still challenging and elusive.The main purpose of this paper is to show that a hypothesis testing paradigm can provide an effective and robust way for computing solutions to motion problems. In particular, we show that computing a solution to a motion problem is equivalent to selecting a correct hypothesis from a set of possible ones, and rejecting or validating a hypothesis involves similar computations. The proposed method is inherently suitable for implementations in parallel machines. We use a variety of real images, like outdoors scenes, truck motion, and robot scenes to test and evaluate our method.
EFFECT OF CARBON ON THE WELDABILITY OF FE-MN-AL ALLOYS
(1990-02-01)
CHOU, CP
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LEE, CH
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
EFFECTS OF HEAT-TREATMENT AND ION DOPING OF INDIUM OXIDE
(1989-06-01)
LEE, CH
;
KUO, CV
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LEE, CL
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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
FAST CLOSEST CODEWORD SEARCH ALGORITHM FOR VECTOR QUANTIZATION
(1994-06-01)
LEE, CH
;
CHEN, LH
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
One of the most serious problems for vector quantisation is the high computational complexity of searching for the closest codeword in the codebook design and encoding phases. The authors present a fast algorithm to search for the closest codeword. The proposed algorithm uses two significant features of a vector, mean value and variance, to reject many unlikely codewords and saves a great deal of computation time. Since the proposed algorithm rejects those codewords that are impossible to be the closest codeword, this algorithm introduces no extra distortion than conventional full search method. The results obtained confirm the effectiveness of the proposed algorithm.
HIGH-SPEED CLOSEST CODEWORD SEARCH ALGORITHMS FOR VECTOR QUANTIZATION
(1995-05-01)
LEE, CH
;
CHEN, LH
;
資訊工程學系
;
Department of Computer Science
One of the most serious problems for vector quantization is the high computational complexity involved in searching for the closest codeword through a codebook in both codebook design and encoding phases. In this paper, based on the assumption that the distortion is measured by the squared Euclidean distance, two high-speed search methods will be proposed to speed up the search process. The first one uses the difference between the mean values of two vectors to reduce the search space. The second is to find the Karhunen-Loeve transform (KLT) for the distribution of the set of training vectors and then applies the partial distortion elimination method to the transformed vectors. Experimental results show that the proposed methods can reduce lots of mathematical operations.
HIPEC - HIGH PERFORMANCE EXTERNAL VIRTUAL MEMORY CACHING
(1994)
LEE, CH
;
CHEN, MC
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CHANG, RC
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資訊工程學系
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Department of Computer Science
MICROSTRUCTURAL STUDIES OF FE-MN-AL-SI WELD METAL
(1989-06-01)
CHOU, CP
;
LEE, CH
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
ON CORRESPONDENCE, LINE TOKENS AND MISSING TOKENS
(1995-11-01)
LEE, CH
;
JOSHI, A
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資訊工程學系
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Department of Computer Science
In this article, the authors expand on some of their previous work on correspondence and propose a system that can correspond in the presence of both point and line tokens, or a mix of them. It can also work if some tokens present in one frame are not present in the other. The proposed algorithm is an amalgamation of reductionist and holist paradigms. We establish that properties which remain invariant for whole image sequences and sequences consisting of corresponding parts from each image frame can be used to establish correspondence. Extensive computer simulation results on synthesised data as well as real image sequences are presented to validate our claims.
ON THE PROBLEM OF CORRESPONDENCE IN RANGE DATA AND SOME INELASTIC USES FOR ELASTIC NETS
(1995-05-01)
JOSHI, A
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LEE, CH
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資訊工程學系
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Department of Computer Science
In this work, the authors propose a novel method to obtain correspondence between range data across image frames using neural like mechanisms. The method is computationally efficient and tolerant of noise and missing points. Elastic nets, which evolved out of research into mechanisms to establish ordered neural projections between structures of similar geometry, are used to cast correspondence as an optimization problem. This formulation is then used to obtain approximations to the motion parameters under the assumption of rigidity (inelasticity). These parameters can be used to recover correspondence. Experimental results are presented to establish the veracity of the scheme and the method is compared to earlier attempts in this direction.
TEM STUDIES OF DO3 STRUCTURE IN FE-30MN-9AL-0.4C WELD METAL
(1989-11-01)
CHOU, CP
;
LEE, CH
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
THE EVALUATION OF HOT CRACK SUSCEPTIBILITY OF FE-30MN-10AL-XC WELD METAL BY USING VARESTRAINT TEST
(1989-07-01)
CHOU, CP
;
LEE, CH
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
THE INFLUENCE OF CARBON CONTENT ON AUSTENITE-FERRITE MORPHOLOGY IN FE-MN-AL WELD METALS
(1989-11-01)
CHOU, CP
;
LEE, CH
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
WELD METAL CHARACTERISTICS OF DUPLEX FE-30WT-PERCENT-MN-10WT-PERCENT-AL-XC ALLOYS
(1989-10-01)
CHOU, CP
;
LEE, CH
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University