• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.617-635
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• 2020

The purpose of this study is to discuss how to improve the maneuverability of lifting and diving for underwater vehicle's vertical motion. Therefore, to solve these problems, applied the 3-D numerical simulation, Taguchi's Design of Experiment (DOE), and intelligent parameter design methods, etc. We planned four steps as follows: firstly, we applied the 2-D flow simulation with NACA series, and then through the Taguchi's dynamic method to analyze the sensitivity (β). Secondly, take the data of pitching torque and total resistance from the Taguchi orthogonal array (L9), the ignal-to-noise ratio (SNR), and analysis each factorial contribution by ANOVA. Thirdly, used Radial Basis Function Network (RBFN) method to train the non-linear meta-modeling and found out the best factorial combination by Particle Swarm Optimization (PSO) and Weighted Percentage Reduction of Quality Loss (WPRQL). Finally, the application of the above methods gives the global optimum for multi-quality characteristics and the robust design configuration, including L/D is 9.4:1, the foreplane on the hull (Bow-2), and position of the sail is 0.25 Ls from the bow. The result shows that the total quality is improved by 86.03% in comparison with the original design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1273-1279
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• 2011

The variable-swash-plate compressor has recently been adopted as a vehicle compressor to improve fuel efficiency. The rotation torque in the variable-swash-plate compressor and the pressure-affected piston have a great influence on the swash-plate design and deformation. This paper suggests the optimal configuration design by using Chebyshev orthogonal polynomial and optimization techniques. The orthogonal array (OA) and analysis of variance (ANOVA) techniques and response surface optimization, are employed to determine the main effects and their optimal design variables. According to the optimal design, we confirm an effective design variable in swash plate and explain the optimal solution, the usefulness for satisfying the constraints of maximum stress and deformation.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.88-96
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• 2023

KOMPSAT (Korean Multi-Purpose Satellite) is a Low-Earth-Orbit (LEO) satellite under development in Korea. Its performance has been steadily improving. At this time, power demand of the payload increased according to performance improvement of the payload. Accordingly, design of the satellite, such as design of the internal power supply device and the configuration of the solar array, was changed. Thus, many considerations are required according to an increase in power when designing power EGSE (Electric Ground Support Equipment) for supplying power to satellites and conduct satellite integration tests. This paper deals with matters to be considered when designing power EGSE according to changes in satellite power requirements according to payloads and increase in power requirements.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.44-44
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• 2003

As a basic measurement tool in the areas of animal models of human disease, gene expression and therapy, and drug discovery and development, small animal PET imaging is being used increasingly. An ideal small animal PET should have high sensitivity and high and uniform resolution across the field of view to achieve high image quality. However, the combination of long narrow pixellated crystal array and small ring diameter of small animal PET leads to the degradation of spatial resolution for the source located at off center. This degradation of resolution can be improved by determining the depth of interaction (DOI) in the crystal and by taking into account the information in sorting the coincident events. Among a number of 001 identification schemes, dual layer phsowich detector has been widely investigated by many research groups due to its practicability and effectiveness on extracting DOI information. However, the effects of each crystal length composing dual layer phoswich detector on DOI measurements and image qualities were not fully characterized. In order to minimize the DOI effect, the length of each layer of phoswich detector should be optimized. The aim of this study was to perform simulations using a simulation tool, GATE to design the optimum lengths of crystals composing a dual layer phoswich detector. The simulated small PET system employed LSO front layer LuYAP back layer phoswich detector modules and the module consisted of 8${\times}$8 arrays of dual layer crystals with 2 mm ${\times}$ 2 mm sensitive area coupled to a Hamamatsu R7600 00 M64 PSPMT. Sensitivities and variation of radial resolutions were simulated by varying the length of LSO front layer from 0 to 10 mm while the total length (LSO + LuYAP) was fixed to 20 mm for 10 cm diameter ring scanner. The radial resolution uniformity was markedly improved by using DOI information. There existed the optimal lengths of crystal layers to minimize the variation of radial resolutions. In 10 cm ring scanner configuration, the radial resolution was kept below 3.4 mm over 8 cm FOV while the sensitivity was higher than 7.4% for LSO 5 mm : LuYAP 15 mm phoswich detector. In this study, the optimal length of dual layer phoswich detector was derived to achieve high and uniform radial resolution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5452-5457
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• 2012

It is saving material cost and construction cost by replacing conventional building materials, and It has advantages for aesthetic value. In the Europe, the United States, Japan and other country research about BIPV is actively being carried out and marketability is also being infinity expanding. Arch type PV systems efficiency characteristics is different depending on PV array's directly connection, parallel connection and arches angle, but is a lack of analysis on this nowadays. When the arch type PV system design up, they consider about aesthetic value and they didn't consider about generation efficiency. In this paper, we try to improve the efficiency through optimization of arch type PV system and estimation of the efficiency parameters of the arch type PV system, such as latitude, longitude, temperature, insolation, arch angle and each kind loss from system organization. For improving Arched PV system efficiency, proposed multiple control inverter system, and using simulation tool of Arched PV system "Solar pro", flat-plate type and many arch type PV system configuration the driving characteristics were compared and analyzed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.27 no.3
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• pp.127-143
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• 2022

Recently, many attempts to run numerical ocean models in cloud computing environments have been tried actively. A cloud computing environment can be an effective means to implement numerical ocean models requiring a large-scale resource or quickly preparing modeling environment for global or large-scale grids. Many commercial and private cloud computing systems provide technologies such as virtualization, high-performance CPUs and instances, ether-net based high-performance-networking, and remote direct memory access for High Performance Computing (HPC). These new features facilitate ocean modeling experimentation on commercial cloud computing systems. Many scientists and engineers expect cloud computing to become mainstream in the near future. Analysis of the performance and features of commercial cloud services for numerical modeling is essential in order to select appropriate systems as this can help to minimize execution time and the amount of resources utilized. The effect of cache memory is large in the processing structure of the ocean numerical model, which processes input/output of data in a multidimensional array structure, and the speed of the network is important due to the communication characteristics through which a large amount of data moves. In this study, the performance of the Regional Ocean Modeling System (ROMS), the High Performance Linpack (HPL) benchmarking software package, and STREAM, the memory benchmark were evaluated and compared on commercial cloud systems to provide information for the transition of other ocean models into cloud computing. Through analysis of actual performance data and configuration settings obtained from virtualization-based commercial clouds, we evaluated the efficiency of the computer resources for the various model grid sizes in the virtualization-based cloud systems. We found that cache hierarchy and capacity are crucial in the performance of ROMS using huge memory. The memory latency time is also important in the performance. Increasing the number of cores to reduce the running time for numerical modeling is more effective with large grid sizes than with small grid sizes. Our analysis results will be helpful as a reference for constructing the best computing system in the cloud to minimize time and cost for numerical ocean modeling.