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101.
Jae‐Ho Hur Hyouk‐Kyun Kwon Yung‐Lyul Lee 《International journal of imaging systems and technology》2006,16(1):24-33
In this study, we propose a heterogeneous transcoding method of converting an H.264/Advanced video coding (AVC) Baseline profile (BP) video bitstream into an MPEG‐4 Visual simple profile (VSP) video bitstream. The proposed method reduces the spatial resolution for mobile terminals, which support only low resolution video bitstreams. When the H.264/AVC BP video bitstream is transformed into the MPEG‐4 VSP video bitstream, the conversions between the H.264/AVC BP block types and the MPEG‐4 VSP block types are performed by analyzing the macroblocks (MBs) conversion probability and calculating the difference values of motion vector. The proposed transcoding method runs on average 5.5 times faster than the cascaded transcoding methods, for a degradation of the PSNR (peak‐signal‐to ratio) of less than 0.5 dB. © 2006 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 16, 24–33, 2006 相似文献
102.
Young Seok Han Min Kyu Park Chang Won Kim Moon Gi Kang 《International journal of imaging systems and technology》2006,16(3):92-102
Complementary color filter array (CCFA) is widely used in consumer‐level digital video cameras, since it not only has high sensitivity and good signal‐to‐noise ratio in low‐light condition but also is compatible with the interlaced scanning used in broadcast systems. However, the full‐color images obtained from CCFA suffer from the color artifacts such as false color and zipper effects. These artifacts can be removed with edge‐adaptive color interpolation (ECI) approaches which are generally used in primary color filter array (PCFA). Unfortunately, the unique array pattern of CCFA makes it difficult that CCFA adopts ECI approaches. Therefore, to apply ECI approaches suitable for CCFA to color interpolation is one of the major issues to reconstruct the full‐color images. In this paper, we propose a new ECI algorithm for CCFA. To estimate an edge direction precisely and enhance the quality of the reconstructed image, a function of spatial variances is used as a weight, and new color conversion matrices are presented for considering various edge directions. Experimental results indicate that the proposed algorithm outperforms the conventional method with respect to both objective and subjective criteria. © 2006 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 16, 92–102, 2006 相似文献
103.
Hot band annealing is known to be a prerequisite for good magnetic properties irrespective of manufacturing methods in grain‐oriented Fe‐3 wt.% Si electrical steels. In this study, the effects of hot band annealing on magnetic properties were investigated in 3% grain‐oriented electrical steels of low soluble AI contents and one‐stage cold rolling. Microstructure and precipitate distribution were compared with hot band annealing conditions. Secondary recrystallization behaviour with hot band annealing condition was also discussed. 相似文献
104.
Seok Cho Se-Young Chun Sang-Ki Moon Won-Pil Baek Yoo Kim 《Nuclear Engineering and Design》2005,235(1):77-90
KAERI has performed an experimental study on the critical heat flux (CHF) under zero flow conditions with a non-uniformly heated 3 × 3 rod bundle. Experimental conditions are in the range of a system pressure from 0.50 to 14.96 MPa and inlet water subcooling enthalpies from 68 to 352 kJ/kg. The test section used in the present experiments consisted of a vertical flow channel, upper and lower plenums, and a non-uniformly heated 3 × 3 rod bundle. The experimental results show that the CHFs in low-pressure conditions are somewhat scattered within a narrow range. As the system pressure increases, however, the CHFs show a good parametric trend. The CHFs occur in the upper region of the heated section, but the locations of the detected CHFs move gradually in a downward direction with the increase of the system pressure. Even though the effects of the inlet water subcooling enthalpies and system pressure of the flooding CHF are relatively smaller than those of the flow boiling CHF, the CHF increases by increasing the inlet water subcooling enthalpies. Several existing correlations for the countercurrent flooding CHF based on Wallis's flooding correlation and Kutateladze's criterion for the onset of flooding are compared with the CHF data obtained in the present experiments to examine the applicability of the correlations. 相似文献
105.
Moon‐Kyun Shin Gyung‐Jin Park 《International journal for numerical methods in engineering》2005,64(5):599-617
Optimization has been successfully applied to systems with a single discipline. Since many disciplines are involved in a coupled fashion in modern engineering, multidisciplinary design optimization (MDO) technology has been developed. MDO algorithms are designed to solve the coupled aspects generated from the interdisciplinary relationship. In a general MDO algorithm, a large design problem is decomposed into smaller ones which can be easily solved. Although various methods have been proposed for MDO, research is still in the early stage. This study proposes a new MDO method which is named MDO based on independent subspaces (MDOIS). Many real engineering problems consist of physically separate components and they can be independently designed. The inter‐relationship occurs through coupled physics. MDOIS is developed for such problems. In MDOIS, a large system is decomposed into small subsystems. The coupled aspects are solved via system analysis which solves the coupled physics. The algorithm is mathematically validated by showing that the solution satisfies the Karush–Kuhn–Tucker condition. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
106.
This paper proposes performance tuning methods for a PID controller for a robotic manipulator. The design procedures of an inverse optimal PID control method employed to assure extended disturbance input‐to‐state stability (ISS) are suggested. The performance tuning methods for an inverse optimal PID control are derived from the performance limitation and the bounds of the state vector. Also, the effects of proportional and integral gains are considered in evaluating the performance tuning. Finally, we show the validity of the performance tuning methods through the experiment on a robotic manipulator. 相似文献
107.
A fast path planning by path graph optimization 总被引:1,自引:0,他引:1
Joo Young Hwang Jun Song Kim Sang Seok Lim Kyu Ho Park 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》2003,33(1):121-129
A fast path planning method by optimization of a path graph for both efficiency and accuracy is proposed. A conventional quadtree-based path planning approach is simple, robust, and efficient. However, it has two limitations. We propose a path graph optimization technique employing a compact mesh representation. A world space is triangulated into a base mesh and the base mesh is simplified to a compact mesh. The compact mesh representation is object-dependent; the positions of vertexes of the mesh are optimized according to the curvatures of the obstacles. The compact mesh represents the obstacles as accurately as the quadtree even though using much fewer vertexes than the quadtree. The compact mesh distributes vertexes in a free space in a balanced way by ensuring that the lengths of edges are below an edge length threshold. An optimized path graph is extracted from the compact mesh. An iterative vertex pushing method is proposed to include important obstacle boundary edges in the path graph. Dijkstra's shortest path searching algorithm is used to search the shortest path in the path graph. Experimental results show that the path planning using the optimized path graph is an order of magnitude faster than the quadtree approach while the length of the path generated by the proposed method is almost the same as that of the path generated by the quadtree. 相似文献
108.
Hee Seok Song Jae Kyeong Kim Yeong Bin Cho Soung Hie Kim 《Artificial Intelligence Review》2004,21(2):161-184
Customer retention is an increasinglypressing issue in today's competitiveenvironment. This paper proposes a personalizeddefection detection and prevention procedurebased on the observation that potentialdefectors have a tendency to take a couple ofmonths or weeks to gradually change theirbehaviour (i.e., trim-out their usage volume)before their eventual withdrawal. For thispurpose, we suggest a SOM (Self-Organizing Map)based procedure to determine the possiblestates of customer behaviour from pastbehaviour data. Based on this staterepresentation, potential defectors aredetected by comparing their monitoredtrajectories of behaviour states with frequentand confident trajectories of past defectors.Also, the proposed procedure is extended toprevent the defection of potential defectors byrecommending the desirable behaviour state forthe next period so as to lower the likelihoodof defection. For the evaluation of theproposed procedure, a case study has beenconducted for a Korean online game site. Theresult demonstrates that the proposed procedureis effective for defection prevention andefficiently detects potential defectors withoutdeterioration of prediction accuracy whencompared to that of the MLP (Multi-LayerPerceptron) neural networks. 相似文献
109.
Dong Ho Bae Chul Han Kim Seon Young Cho Jung Kyun Hong Chon Liang Tsai 《Journal of Mechanical Science and Technology》2002,16(9):1054-1064
Numerical prediction of welding-induced residual stresses using the finite element method has been a common practice in the
development or refinement of welded product designs. Various researchers have studied several thermal models associated with
the welding process. Among these thermal models, ramp heat input and double-ellipsoid moving source have been investigated.
These heat-source models predict the temperature fields and history with or without accuracy. However, these models can predict
the thermal characteristics of the welding process that influence the formation of the inherent plastic strains, which ultimately
determines the final state of residual stresses in the weldment. The magnitude and distribution of residual stresses are compared.
Although the two models predict similar magnitude of the longitudinal stress, the double-ellipsoid moving source model predicts
wider tensile stress zones than the other one. And, both the ramp heating and moving source models predict the stress results
in reasonable agreement with the experimental data. 相似文献
110.
Seok Jin Lim Suk Jae Jeong Kyung Sup Kim Myon Woong Park 《The International Journal of Advanced Manufacturing Technology》2006,28(5-6):618-625
Today’s business environment is experiencing as a period of expansion and the globalization. Therefore, a distribution plan
with low cost and high customer satisfaction in supply chain management (SCM) has been widely investigated. The purpose of
this study is to establish optimal distribution planning in the supply chain. In this paper, a hybrid approach involving a
genetic algorithm (GA) and simulation is presented to solve this problem. The GA is employed in order to quickly generate
feasible distribution sequences. Considering uncertain factors such as queuing, breakdowns and repairing time in the supply
chain, the simulation is used to minimize completion time for the distribution plan. The computational results for an example
of a simple supply chain are given and discussed to validate the proposed approach. We obtained a more realistic distribution
plan with optimal completion time by performing the iterative hybrid GA simulation procedure which reflects the stochastic
nature of supply chains. 相似文献