• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.137-144
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• 2006

This study is concerned with the relation between steelbelt width and belt edge separation of a tire. Belt edge separation causes tire burst and threatens passenger's safety. For the reason, it is important to predict durability caused by belt edge separation in the early stage of the tire structure design. Usually, passenger car tires have two layers of steelbelts having opposite steel cord's angles, which makes a shear behaviour between each belt layer. Shear behaviour is one of reason to cause belt edge separation. In this study, to predict belt edge separation, we suggested the prediction method of belt edge separation and evaluated the effect of steelbelt width on the belt edge separation using FEM. We also studied on main parameters to affect shear behaviour at the belt edge area.

• Nuclear Engineering and Technology
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• v.29 no.6
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• pp.459-467
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• 1997

The steady-state behavior of recycling neutral atoms in a tokamak edge region has been analyzed through a two-dimensional Monte Carlo simulation. A particle tracking algorithm used in earlier research on the neutral particle transport is applied to this Monte Carlo simulation in order to perform more accurate calculations with the EDGETRAN code which was previously developed for a two-dimensional edge plasma transport in the authors' laboratory. The physical model of neutral recycling includes charge-exchange and ionization interactions between plasmas and neutral atoms. The reflection processes of incident particles on the device wall are described by empirical formulas. Calculations for density, energy, and velocity distributions of neutral deuterium-tritium atoms have been carried out for a medium-sized tokamak with a double-null configuration based on the KT-2 conceptual design. The input plasma parameters such as plasma density, ion and electron temperatures, and ion fluid velocity are provided from the EDGETRAN calculations. As a result of the present numerical analysis, it is noticed that a significant drop of the neutral atom density appears in the region of high plasma density and that the similar distribution of neutral energy to that of plasma ions is present as frequently reported in other studies. Relations between edge plasma conditions and the neutral recycling behavior are discussed from the numerical results obtained herein.

• Journal of the Mineralogical Society of Korea
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• v.30 no.2
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• pp.59-70
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• 2017

$SiO_2$ is one of the most abundant constituents of the Earth's crust and mantle. Probing its electronic structures at high pressures is essential to understand their elastic and thermodynamic properties in the Earth's interior. The in situ high-pressure x-ray Raman scattering (XRS) experiment has been effective in providing detailed bonding transitions of the low-z materials under extreme compression. However, the relationship between the local atomic structures and XRS features at high pressure has not been fully established. The ab initio calculations have been used to overcome such experimental difficulties. Here we report the partial density of states (PDOS) of O atoms and the O K-edge XRS spectra of ${\alpha}-quartz$, ${\alpha}-cristobalite$, and $CaCl_2$-type $SiO_2$ phases calculated using ab initio calculations based on the full-potential linearized augmented plane wave (FP-LAPW) method. The unoccupied O PDOSs of the $CaCl_2$-type $SiO_2$ calculated with and without applying the core-hole effects present significantly distinctive features. The unoccupied O p states of the ${\alpha}-quartz$, ${\alpha}-cristobalite$ and $CaCl_2$-type $SiO_2$ calculated with considering the core-hole effect present similar features to their calculated O K-edge XRS spectra. This confirms that characteristic features in the O K-edge XRS stem from the electronic transition from 1s to unoccupied 2p states. The current results indicate that the core-hole effects should be taken in to consideration to calculate the precise O K-edge XRS features of the $SiO_2$ polymorphs at high pressure. Furthermore, we also calculated O K-edge XRS spectrum for $CaCl_2$-type $SiO_2$ at ~63 GPa. As the experimental spectra for these high pressure phases are not currently available, the current results for the $CaCl_2$-type $SiO_2$ provide useful prospect to predict in situ high-pressure XRS spectra.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.253-256
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• 2014

Functionalization of zigzag graphene nanoribbon (ZGNR) segment containing 120 C atoms with pyridine (3NV-ZGNR) defects was investigated on the basis of density-functional theory (DFT) calculations, results show that edge-modified ZGNRs by Sc can adsorb multiple hydrogen molecules in a quasi-molecular fashion, thereby can be a potential candidate for hydrogen storage. The stability of Sc functionalization is dictated by a strong binding energy, suggesting a reduction of clustering of metal atoms over the metal-decorated ZGNR.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.2006-2010
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• 2005

This study is concerned with the relation between steelbelt and belt edge separation. Belt edge separation causes tire burst and threatens passenger's safety. For that reason, it is important to predict durability caused by belt edge separation first in tire structure design step. In this study, to predict belt edge separation, we suggest the prediction method of belt edge separation and evaluate the effect of steelbelt width on the belt edge separation using FEM. We study on analysis parameter also to do exact estimation about the shear behaviour of belt edge area.

• Transactions of the Society of Information Storage Systems
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• v.2 no.3
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• pp.184-188
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• 2006

In recent years the flying height of the head/slider has been decreasing in order to increase the recording density of hard disk drive (HDD). Accordingly, it was predicted that direct contact between slider and disk surface (slider slap) can cause defects on the disk such as scratch and particle generation. In this work, we theoretically demonstrate the effect of rounded-edge slider using Hertzian contact theory. Depth and width of scratch were predicted by plowing model. Furthermore, as we fabricated rounded-edge slider, rounded-edge slider was tested and compared with sharp-edge slider. The experimental results show rounded-edge was effective for reducing scratch depth.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.403-411
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• 2010

Essentials of understanding the geochemical evolution and geophysical processes in Earth's system are macroscopic properties and atomistic (and electronic) structures of Earth materials. Recent advances in quantum calculations based on the density functional theory allow us to unveil the previously unknown details of local atomic structures in diverse silicates in Earth's interior. Here, we report the O K-edge ELNES (energy-loss near-edge structure; ELNES) spectra and PLDOS (partial local density of states) for oxygen atoms in ${\alpha}$-quartz and stishovite using the quantum calculations based on FP-LAPW (full potential linearized augmented plane wave). The calculated O K-edge ELNES spectrum of ${\alpha}$-quartz shows a strong peak at ~538 eV due to comer-sharing oxygen linking two $SiO_4$ tetrahedra and that for stishovite shows two distinct peaks at ~537 and ~543 eV corresponding to edge-sharing oxygen linking $SiO_6$ octahedra. The significant differences in spectral features of O K-edge ELNES spectra suggest that the O K-edge features can be useful indicator to distinguish various oxygen sites in diverse crystal and amorphous silicates in the Earth's interior.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.1
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• pp.63-71
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• 1983

A dye-edge tracking algorithm was used to determine the corresponding points in the two images(anterior-posterior and lateral) of the digital subtraction biplane angiography. This correspondence was used to reconstruct three dimensional images of cerebral artery in a dog experiment. The method was tested by comparing the measured image of oblique view with the computed reconstructed image. For the present study, we have developed three new algorithms. The first algorithm is to determine the corresponding dye-edge points using the fact the dye density at the moving edge avows the same changing pattern in the two projection views. This moving pattern of dye-edge density is computed using a matching method of cross-correlation for the two sequential frames' dye density. The second algorithm is for simplified perspective transformation, and the third one is to identify the specific corresponding points on the small vessels. The present method can be applied to compute the blood velocity using the dye-edge displacement and the three- dimensional distance data.

• Journal of the Korean Magnetics Society
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• v.16 no.5
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• pp.229-233
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• 2006

We investigated the magnetic properties of Fe nanostripes by using the all electron full-potenial linearized augmented plane-wave (FLAPW) energy band method within the generalized gradient approximation (GGA). The magnetic moments of the Fe atoms in the edge Fe chains of the stripes composed of three, five, and seven chains have saturated values of 2.97 or 2.98 ${\mu}_B$, and the values of the center chains are 2.82 ${\mu}_B$ which is similar to that of 2D square lattice. The charge and spin density contour plots showed that the flat distribution in the edge region of the stripes, and it is due to the spilled out p-electrons from the atoms in the edge line. The calculated density of states for the edge atoms in the stripes with seven Fe chains showed that the narrowed width compared to that of center atoms due to the band narrowing effect at the edge.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.212-216
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• 2007

Predicting microcracking properties of the composite laminates in nonuniform stress conditions was the subject in this paper. The uniform stress field meant the stresses were independent of the width direction. The material was the 954-2A/IM7 laminates containing a central hole. Microcracks initiated at the edge of the hole and propagated into the laminate. Because the tensile stress concentration decreased with distance, the microcracks were arrested before the edge of the laminate. Because carbon fiber composites were opaque, a x-ray method was used to detect the length of the propagating microcracks. The microcracking at the near edge of the hole could be reasonably predicted by considering the local laminate stresses and the microcracking toughness measured in unnotched laminates. However, the date away from the hole did not agree with the predictions. The local microcrack density was always much higher than that predicted by the local laminate stress.