• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.33-40
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• 2019

As aerospace industry has been activated recently, it is required to commercialize composite analysis software. Until now, commercial software has been mainly used for analyzing composites, but it has been difficult to use due to high price and limited functions. In order to solve this problem, automatic analysis software for both in-plane and corner radius strength, which are all made on-line and generalized, has recently been developed. However, these have the disadvantage that they can not be analyzed simultaneously with multiple failure criteria. In this paper, we propose a method to greatly improve the processing speed while simultaneously handling the analysis of multiple failure criteria using a parallel processing platform that only works with a GPU equipped with a CUDA core. We have obtained satisfactory results when the analysis speed is experimented on the vast structure data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.977-983
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• 2007

Recently, the number of systems which utilize wireless power transmission to a receiving module in a short distance is increasing. For efficient use of receiving space, coils are wound around the ferrite core to produce electromotive force(emf) in suppling power by wireless transmission. This paper analyzed the magnetic flux density distribution in the ferrite core in magnetic field environment which is uniformly oriented along to a single axis at 125kHz. For numerical analysis, Ansoft Maxwell which is applying the FEM(Finite Element Method) method was used. We studied the variations of the gathered magnetic fluxes to the changes of the relative permeabilities of the ferrite cores. Also we calculated the magnetic flux variation by shaving the ferrite core off for the groove of coil winding. Results showed that using a small ferrite core in magnetic field at 100kHz band can increase the amount of magnetic flux $3{\sim}4 times$ than without the core. The magnetic flux decreased 23% by shaving the core 0.5 mm on the periphery of 4.75 mm radius core with the relative permeability 800.

• Transactions of Materials Processing
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• v.16 no.7
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• pp.530-537
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• 2007

This paper is concerned with the analysis of plastic deformation of bimetal co-extrusion process. Two sets of material combination have been adopted for analysis, i.e. combinations of Cu/Al and Fe/Al. In the first set of material combination, the selected materials are AA 1100 aluminum alloy as hard material and CDA 110 as soft one. This type of material selection is to examine the effect of hard core and soft sleeve and vice versa on the deformation pattern in terms of plastic zone and velocity discontinuity along the contact surface between construction materials. Four different cases of co-extrusion process in terms of material combination and interference bonding were simulated to investigate the effect of material arrangement between core and sleeve, and of bonding on the plastic zones and velocity discontinuity. In the other set of material combination, model materials used as core and sleeve were AA 1100 and AISI 1010, which are relatively soft and hard, respectively. Process parameters except diameter ratio of core to sleeve material such as semi-die angle, reduction in area in global sense and die comer radius have been set constant throughout the simulation to concentrate our effort on the analysis of influence of diameter ratio on deformation behavior such as deformation zone, surface expansion, exit velocity discontinuity between composite materials, and extrusion forces.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.4
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• pp.301-310
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• 2013

The aim of the present study is to enhance query speed of large 3D point cloud indexed in octree by parallel query using multi-cores. Especially, it is focused on developing methods of accessing multiple leaf nodes in octree concurrently to query points residing within a radius from a given coordinates. To the end, two parallel query methods are suggested using different strategies to distribute query overheads to each core: one using automatic division of 'for routines' in codes controlled by OpenMP and the other considering spatial division. Approximately 18 million 3D points gathered by a terrestrial laser scanner are indexed in octree and tested in a system with a 8-core CPU to evaluate the performances of a non-parallel and the two parallel methods. In results, the performances of the two parallel methods exceeded non-parallel one by several times and the two parallel rivals showed competing aspects confronting various query radii. Parallel query is expected to be accelerated by anticipated improvements of distribution strategies of query overhead to each core.

• Nuclear Engineering and Technology
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• v.37 no.4
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• pp.363-374
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• 2005

A heterogeneous thorium-based Kyung Hee Thorium Fuel (KTF) assembly design was assessed for application in the APR-1400 to study the feasibility of using thorium fuel in a conventional pressurized water reactor (PWR). Thermal hydraulic safety was examined for the thorium-based APR-1400 core, focusing on the Departure from Nucleate Boiling Ratio (DNBR) and Large Break Loss of Coolant Accident (LBLOCA) analysis. To satisfy the minimum DNBR (MDNBR) safety limit condition, MDNBR>1.3, a new grid design was adopted, that enabled grids in the seed and blanket assemblies to have different loss coefficients to the coolant flow. The fuel radius of the blanket was enlarged to increase the mass flow rate in the seed channel. Under transient conditions, the MDNBR values for the Beginning of Cycle (BOC), Middle of Cycle (MOC), and End of Cycle (EOC) were 1.367, 1.465, and 1.554, respectively, despite the high power tilt across the seed and blanket. Anticipated transient for the DNBR analysis were simulated at conditions of $112\%$ over-power, $95\%$ flow rate, and $2^{\circ}C$ higher inlet temperature. The maximum peak cladding temperature (PCT) was 1,173K for the severe accident condition of the LBLOCA, while the limit condition was 1,477K. The proliferation resistance potential of the thorium-based core was found to be much higher than that of the conventional $UO_2$ fuel core, $25\%$ larger in Bare Critical Mass (BCM), $60\%$ larger in Spontaneous Neutron Source (SNS), and $155\%$ larger in Thermal Generation (TG) rate; however, the radio-toxicity of the spent fuel was higher than that of $UO_2$ fuel, making it more environmentally unfriendly due to its high burnup rate.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.279-282
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• 2005

We report the millimeter-wave radio observations of molecular cloud cores in Taurus. The observed line is the $N_2H^+$ emission at 93 GHz, which is known to be less affected by molecular depletion. We have compared starless (IRAS-less) cores with star-forming cores. We found that there is no large difference between starless and star-forming cores, in core radius, linewidth, core mass, and radial intensity profile. Our result is in contrast with the result obtained by using a popular molecular line, in which starless cores are larger and less condensed. We suggest that different results mainly come from whether the employed molecular line is affected by depletion or not. We made a virial analysis, and found that both starless and star-forming cores are not far from the critical equilibrium state, in Taurus. Together with the fact that Taurus cores are almost thermally supported, we conclude that starless Taurus cores evolve to star formation without dissipating turbulence. The critical equilibrium state in the virial analysis corresponds to the critical Bonnor-Ebert sphere in the Bonnor-Ebert analysis (Nakano 1998). It is suggested that the initial condition of the molecular cloud cores/globules for star formation is close to the critical equilibrium state/critical Bonnor-Ebert sphere, in the low-mass star forming region.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.343-344
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• 2006

방향성 규소강판을 tape-wound core 형태로 제작하여 가공방법에 따른 자기적 특성을 조사 하였다. 그 결과 곡률반경이 40mm인 시료에서 보자력(Hc)과 포화자속밀도(Bs)는 우수한 값을 나타내었고, 보자력은 0.02Oe, 포화자속밀도는 1.85T 이었다. 현재 국내에서 생산되고 있는 방향성 규소강판의 자속밀도값 보다 우수한 값을 나타내었다. 본 연구로부터 방향성 규소강판을 이용하여 권자심을 제작할 때 도입되는 탄성변형에 대한 대책의 중요성과 코어 소재의 가공방법이 자기적 특성에 미치는 영향을 통해 고효율 방향성 규소강판 개발의 가능성을 확인하였다.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.51.2-51.2
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• 2014

Ultra faint dwarf galaxies (UFDs) are larger but fainter than globular clusters, being the faintest galaxies in the universe. They have been found only in the Local Group. We report the discovery of an UFD in the intracluster field of the Virgo cluster (Virgo UFD1). It is located near the core of Virgo cluster, and far from any massive galaxies. The color magnitude diagram of resolved stars in Virgo UFD1 shows narrow, metal poor red giant branch (RGB), which is very similar to the UFDs in the Local Group. by comparing RGB in this galaxy with 12 Gyr stellar isochrones, we estimate its distance, $d=16.4{\pm}0.4$ Mpc and mean metallicity, $[Fe/H]=-2.4{\pm}0.4$. We derive its integrated photometric properties and structural parameters : V-band absolute magnitude of $MV=-6.3{\pm}0.2$, effective radius of $84{\pm}7pc$, and central surface brightness of ${\mu}V,0=26.49{\pm}0.09$ mag arcsec-2. These properties are similar to these of Local Group UFDs. Virgo UFD1 is the first UFD discovered beyond the Local Group. These results indicate that it may be a fossil remnant of the first galaxies.

• Journal of Environmental Impact Assessment
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• v.11 no.3
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• pp.117-127
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• 2002

This study tested the usefulness of landscape indices for quantifying forest fragmentation due to linear development projects. Research was carried out in the middle-upper Nakdong River watershed, which has been affected by the expressway building, or national road-widening. Landscape indices were calculated from the forest cover maps before and after road-building using FRAGSTATS 3.1. We could successfully demonstrate the forest fragmentation based on landscape indices; (1) patch size decreased, and edge density and patch density increased (2) roads simplified patch shapes, especially in the larger patches, (3) patch core area size decreased, and core area density increased, (4) the distance increased between the focal patch and each of the other patches within the search radius (=1km) as a result of roads. We suggest several important needs for future researches, including continued investigation of scaling issues, development of indices that measure specific components of spatial pattern, and study of the relationships between forest fragmentation and ecological processes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.364-367
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• 2017

The basic design concept of the DACS(Divert and Attitude Control System) propellant is presented and the geometry optimization of the DACS propellant with limited outer diameter and maximum burning rate of the propellant is performed. Two-side burning surface conditions burned at the core and the one side of the propellant are applied to the propellant. And the optimized values for the radius of core, length of propellant, angle of end-side surface are obtained by the PSO algorithm. The direction for DACS propellant design is suggested by analyzing optimized design points for various burning rate.