• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1699-1708
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• 2007

The optimal power flow(OPF) problem was introduced by Carpentier in 1962 as a network constrained economic dispatch problem. Since then, the OPF problem has been intensively studied and widely used in power system operation and planning. In these days, OPF is becoming more and more important in the deregulation environment of power pool and there is an urgent need of faster solution technique for on-line application. To solve OPF problem, many heuristic optimization methods have been developed, such as Genetic Algorithm(GA), Evolutionary Programming(EP), Evolution Strategies(ES), and Particle Swarm Optimization(PSO). Especially, PSO algorithm is a newly proposed population based heuristic optimization algorithm which was inspired by the social behaviors of animals. However, population based heuristic optimization methods require higher computing time to find optimal point. This shortcoming is overcome by a straightforward parallel processing of PSO algorithm. The developed parallel PSO algorithm is implemented on a PC cluster system with 6 Intel Pentium IV 2GHz processors. The proposed approach has been tested on the IEEE 30-bus system. The results showed that computing time of parallelized PSO algorithm can be reduced by parallel processing without losing the quality of solution.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.9
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• pp.1167-1174
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• 1999

In this paper, we present a new technique for the local decomposition of convex structuring elements for morphological image processing. Local decomposition of a structuring element consists of local structuring elements, in which each structuring element consists of a subset of origin pixel and its eight neighbors. Generally, local decomposition of a structuring element reduces the amount of computation required for morphological operations with the structuring element. A unique feature of our approach is the use of linear integer programming technique to determine optimal local decomposition that guarantees the minimal amount of computation. We defined a digital convex polygon, which, in turn, is defined as a convex structuring element, and formulated the necessary and sufficient conditions to decompose a digital convex polygon into a set of basis digital convex polygons. We used a set of linear equations to represent the relationships between the edges and the positions of the original convex polygon, and those of the basis convex polygons. Further. a cost function was used represent the total processing time required for computation of dilation/erosion with the structuring elements in a decomposition. Then integer linear programming was used to seek an optimal local decomposition, that satisfies the linear equations and simultaneously minimize the cost function.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.1
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• pp.17-24
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• 2014

In this paper, we implement and evaluate the performance of a vector-based rasterization algorithm for 3D graphics by using a SIMD (single instruction multiple data) many-core processor architecture. In addition, we evaluate the impact of a data-per-processing elements (DPE) ratio that is defined as the amount of data directly mapped to each processing element (PE) within many-core in terms of performance, energy efficiency, and area efficiency. For the experiment, we utilize seven different PE configurations by varying the DPE ratio (or the number PEs), which are implemented in the same 130 nm CMOS technology with a 500 MHz clock frequency. Experimental results indicate that the optimal PE configuration is achieved as the DPE ratio is in the range from 16,384 to 256 (or the number of PEs is in the range from 16 and 1,024), which meets the requirements of mobile devices in terms of the optimal performance and efficiency.

• Korean Journal of Food Science and Technology
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• v.17 no.3
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• pp.136-140
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• 1985

Optimal quality retentions of cooked rice packed in retort pouch were simulated by computer using various thicknesses of retort pouch (5 to 24mm) and process temperatures (110 to $150^{\circ}C$). Optimal conditions were chosen by the minimal c-values and maximal thiamine retention when good bacteriological lethality (12D processing) was obtained. From the results of calculations, it were shown that the better quality retentions of high tharmal processing can be obtained below pouch thickness of l0mm and that the thickness of pouch is critical factor at higher processing temperature.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.2038-2057
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• 2017

Gaussian learning is a new technology in the computational intelligence area. However, this technology weakens the learning ability of a particle swarm and achieves a lack of diversity. Thus, this paper proposes a vector Gaussian learning strategy and presents an effective approach, named particle swarm optimization based on vector Gaussian learning. The experiments show that the algorithm is more close to the optimal solution and the better search efficiency after we use vector Gaussian learning strategy. The strategy adopts vector Gaussian learning to generate the Gaussian solution of a swarm's optimal location, increases the learning ability of the swarm's optimal location, and maintains the diversity of the swarm. The method divides the states into normal and premature states by analyzing the state threshold of the swarm. If the swarm is in the premature category, the algorithm adopts an inertia weight strategy that decreases linearly in addition to vector Gaussian learning; otherwise, it uses a fixed inertia weight strategy. Experiments are conducted on eight well-known benchmark functions to verify the performance of the new approach. The results demonstrate promising performance of the new method in terms of convergence velocity and precision, with an improved ability to escape from a local optimum.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.1
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• pp.51-56
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• 2006

A computer code was developed to simulate both the thermal stresses introduced during the post-filling stage and the in-plane deformation after ejection process by finite element method based on the plane stress theory. The computer simulation was applied to the mold design of a 2 inch light guide plate (LGP) for thin film transistor (TFT)-liquid crystal displays (LCD). With injection molding experiments based on the design of experiments (DOE) technique, the influences of the processing conditions in injection molding on brightness and uniformity of the LGP were investigated, and the optimal processing parameters were selected to increase the brightness and uniformity. The verification experiment showed that the brightness and uniformity of the LGP were increased dramatically under the selected optimal processing conditions.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.73-76
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• 2000

We investigate the stepwise parallel processing of the serial search which can success the co]1 search at low Ec/Io. The single path Rayleigh fading channel which is worst-case channel model is considered. The typical 3-step cell search is used. The probabilities of detection, miss and false alarm for each step are used in closed forms based on the statistics of CDMA noncoherent demodulator output. The optimal power allocation to each channel and The optimal number of post-detection integrations for each step is obtained. Also, the cumulative probability distribution of the average eel] search time for serial search methods are compared.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.475-478
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• 2004

Tool costs can comprise a significant part of the total operating costs of Flexible Manufacturing Systems. We address the problem of determining the optimal processing times of individual operations and routing mix in FMSs with multiple routes for each part type in order to minimize tool cost, subject to meeting a throughput constraint for each part type. The problem is formulated as a nonlinear program superimposed on a closed queueing network of the FMSs under consideration. Numerical examples reveal the potential of our approach for significant saving in tool costs.

• Transactions of Materials Processing
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• v.13 no.3
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• pp.230-235
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• 2004

A new design based on the appropriate geometry of molded part and type of runner system under the optimal processing conditions was proposed to minimize the micro weld lines on the sub deco surface molded by two shot molding. Theoretical and experimental studies were conducted to examine the cause of the weld lines during the overmolding process in two shot molding. Various dimensions and geometries of substrate$(1^{st}shot)$ and the wall thickness of overmold$(2^{nd}shot)$ have been proposed to avoid the weld lines which are the most inevitable appearance defects occurred on the sub deco. The each design proposal was analyzed by mold flow analysis after part modeling. The analysis results were compared with molded part from mass production tool. It could be seen that from the analysis that the proper geometry of plastic part and type of runner system considering pressure drop under the optimal processing conditions were the most influential factors to avoid weld lines occured on the sub deco.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.4
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• pp.328-337
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• 2004

Tool costs can comprise a significant part of the total operating costs of Flexible Manufacturing Systems. We address the problem of determining the optimal processing times of individual operations and routing mix in FMSs with multiple routes for each part type in order to minimize tool cost, subject to meeting a throughput constraint for each part type. The problem is formulated as a nonlinear program superimposed on a closed queueing network of the FMSs under consideration. Numerical examples reveal the potential of our approach for significant saving in tool costs.