• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.94-99
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• 2006

As part of a Department of Defense Grand Challenge Project, advanced high performance computing (HPC) time-accurate computational fluid dynamics (CFD) techniques have been developed and applied to a new area of aerodynamic research on microjets for control of small and medium caliber projectiles. This paper describes a computational study undertaken to determine the aerodynamic effect of flow control in the afterbody regions of spin-stabilyzed projectiles at subsonic and low transonic speeds using an advanced scalable unstructured flow solver in various parallel computers such as the IBM SP4 and Linux Cluster. High efficiency is achieved for both steady and time-accurate unsteady flow field simulations using advanced scalable Navier-Stokes computational techniques. Results relating to the code's portability and its performance on the Linux clusters are also addressed. Numerical simulations with the unsteady microjets show the jets to substantially alter the flow field both near the jet and the base region of the projectile that in turn affects the forces and moments even at zero degree angle of attack. The results have shown the potential of HPC CFD simulations on parallel machines to provide to provide insight into the jet interaction flow fields leading to improve designs.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.9-14
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• 2006

Estimations of depth, magnetic orientation, and strength of dipole moments aid discrimination between unexploded ordnance (UXO) and non-UXO using magnetic surveys. Such estimations may be hindered by geologic noise, magnetic clutter, and overlapping tails of nearby dipole fields. An improved method of inversion for anomalies of single or multiple dipoles with arbitrary polarization was developed to include intra-inversion filtering and estimation of background field gradients. Data interpolated to grids are flagged so that only nodes nearest to measurement stations are used. To apply intra-inversion filtering to such data requires a gapped filter. Moreover, for data with significant gaps in coverage, or along the edges or corners of survey areas, intra-inversion filters must be appropriately modified. To that end, edge-adaptive and gapped gradient-nulling filters have been designed and tested. Applications are shown for magnetic field data from Chongcho Lake, Sokcho, Korea and the U. S. Army's Aberdeen Proving Ground in Maryland.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2004.11a
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• pp.50-61
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• 2004

Lead and cadmium are potent environmental toxicants that affect populations living in Europe, Americas, and Asia. Identifying transporters for lead and cadmium could potentially 1 help us better understand possible risk factors. The iron transporter divalent metal transporter 1(DMT1) mediates intestinal transport of cadmium, and lead in yeast and fibroblasts overexpressing DMT1. In human intestinal cells knocking down expression of DMT1 attenuated uptake of cadmium and iron but not lead. A possible explanation is the expression of a second transporter for lead in intestine. In astrocytes, however, DMT1 appears to transport lead in an extracellular buffer at pH value. At neutral pH, transport was not mediated by DMT1 but rather by a transporter that is stimulated by bicarbonate and inhibited by 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid. The identity of this lead transporter is under study.

• Biomolecules & Therapeutics
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• v.13 no.1
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• pp.1-6
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• 2005

Lead and cadmium are potent environmental toxicants that affect populations living in Europe. Americas, and Asia. Identifying transporters for lead and cadmium could potentially 1 help us better understand possible risk factors. The iron transporter, divalent metal transporter 1 (DMT1), mediates intestinal transport of cadmium, and lead in yeast and fobroblasts overexpressing DMT1. In human intestinal cells knocking down expression of DMT1 attenuated uptake of cadmium and iron but not lead. A possible explanation is the expression of a second transporter for lead in intestine. In astrocytes, however, DMT1 appears to transport lead in an extracellular buffer at pH value. At neutral pH, transport was not mediated by DMT1 but rather by a transporter that is stimulated by bicarbonate and inhibited by 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid. The identity of this lead transporter will beverified by future study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.2
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• pp.227-233
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• 2015

In this study, an indoor test environment was developed for studying the vision stabilizer of an unmanned vehicle, using a virtual environment and a 6-axis motion simulator. The real driving environment was replaced by a virtual environment based on the Aberdeen Proving Ground bump test course for military tank testing. The vehicle motion was reproduced by a 6-axis motion simulator. Virtual reality driving courses were displayed in front of the vision stabilizer, which was located on the top of the motion simulator. The performance of the stabilizer was investigated by checking the image of the camera, and the pitch and roll angles of the stabilizer captured by the IMU sensor of the camera.

• Transactions on Electrical and Electronic Materials
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• v.1 no.4
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• pp.1-6
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• 2000

The mechanical strength of silicon carbide dose nor permit the use of diffusion as a means to achieve selective doping as required by most electronic devices. While epitaxial layers may be doped during growth, ion implantation is needed to define such regions as drain and source wells, junction isolation regions, and so on. Ion activation without an annealing cap results in serious crystal damage as these activation processes must be carried out at temperatures on the order of 1600$^{\circ}C$. Ion implanted silicon carbide that is annealed in either a vacuum or argon environment usually results in a surface morphology that is highly irregular due to the out diffusion of Si atoms. We have developed and report a successful process of using silicon overpressure, provided by silane in a CAD reactor during the anneal, to prevent the destruction of the silicon carbide surface, This process has proved to be robust and has resulted in ion activation at a annealing temperature of 1600$^{\circ}C$ without degradation of the crystal surface as determined by AFM and RBS. In addition XPS was used to look at the surface and near surface chemical states for annealing temperatures of up to 1700$^{\circ}C$. The surface and near surface regions to approximately 6 nm in depth was observed to contain no free silicon or other impurities thus indicating that the process developed results in an atomically clean SiC surface and near surface region within the detection limits of the instrument(${\pm}$1 at %).