• The magazine of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.23-34
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• 2010

• Proceedings of the Korean Vacuum Society Conference
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• 2005.08a
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• pp.156-156
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• 2005

• Applied Microscopy
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• v.26 no.2
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• pp.235-241
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• 1996

Amophization and decomposition behaviour in $Mg_{62}Cu_{26}Y_{12}$ alloy prepared by melt spinning method and wedge type metal mold casting method have been investigated by a detailed transmission electron microscopy. Amorphous phase has formed in melt-spun ribbon. In the case of the wedge type specimen, however, the amorphous phase has formed only around the tip area within about 2 mm thickness. The remaining part of the wedge type specimen consists of crystalline phases, $Mg_{2}Cu\;and\;Cu_{2}Y$. The supercooling for crystallization behaviour of the amorphous $Mg_{62}Cu_{26}Y_{12}$ alloy, ${\Delta}T_x$ has been measured to be about 60 K. Such a large undercooling of the crystallization bahaviour enables formation of the amorphous phase in the $Mg_{62}Cu_{26}Y_{12}$ alloy under the cooling rate of $10^{2}K/s$. The amorphous $Mg_{62}Cu_{26}Y_{12}$ has decomposed into crystalline phases, $Mg_{2}Cu\;and\;Cu_{2}Y$ after heat treatment at $170^{\circ}C\;and\;250^{\circ}C$.

• Journal of Powder Materials
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• v.23 no.1
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• pp.8-14
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• 2016

A bulk-type Ta material is fabricated using the kinetic spray process and its microstructure and physical properties are investigated. Ta powder with an angular size in the range $9-37{\mu}m$ (purity 99.95%) is sprayed on a Cu plate to form a coating layer. As a result, ~7 mm-sized bulk-type high-density material capable of being used as a sputter material is fabricated. In order to assess the physical properties of the thick coating layer at different locations, the coating material is observed at three different locations (surface, center, and interface). Furthermore, a vacuum heat treatment is applied to the coating material to reduce the variation of physical properties at different locations of the coating material and improve the density. OM, Vickers hardness test, SEM, XRD, and EBSD are implemented for analyzing the microstructure and physical properties. The fabricated Ta coating material produces porosity of 0.11~0.12%, hardness of 311~327 Hv, and minor variations at different locations. In addition, a decrease in the porosity and hardness is observed at different locations upon heat treatment.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.30-35
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• 2014

According to weight lightning trend of automobile body, necessity of resistance spot welding (RSW) of Mg alloy on automobile industry is increasing rapidly because of the highest specific strength among commercial metals. Mg alloy has low electric resistance and high thermal conductivity like as Al alloy, so that needs applying high current in short time when welding. Thick oxide film of Mg alloy pollutes the electrodes and makes partial current carrying paths when on welding. Partial current carrying paths signify excessive concentration of current. There can initiate expulsion easily and reduces electrode life rapidly. Generating partial current carrying paths and expulsions are influenced by shapes of electrode. Therefore, electrode life also influenced by shape. In this study, we perform life test of RSW electrode of radius type. Measure tensile shear load and nugget size every spot alternately. As a result, radius type electrode can extend life over twice as dome type electrode.

• Journal of Animal Science and Technology
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• v.47 no.1
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• pp.99-106
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• 2005

This study was carried out to investigate the effects of addition of citron peel powder(OJ 0/0, 0.60/0, 0.9 %) on proximate composition, minerals, vitamin A, C content and fatty acid composition of emulsion-type sausages. The moisture content of sausage containing 0.3% citron peel powder were significantly(P< 0.05) higher compared to those for control. The crude fat content of sausage containing citron peel powder were significantly( P< 0.05) lower compared to those for control. The crude ash content of sausage containing 0.9% citron peel powder were significantly(P< 0.05) higher compared to those for control. The minerals, vitamin A and C content of sausage containing citron peel powder were significantly(P < 0.05) higher compared to those for control. The palmitic acid(CI6: 0) and linoleic acid(CI8: 2) content of sausage containing citron peel powder were higher compared to those for control, but the palmitoleic acid(CI6: I) content of sausage containing 0.9% citron peel powder were lower. The total saturated fatty acid content of sausage containing 0.3% citron peel powder were significantly(P < 0.05) lower compared to those for control.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.9
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• pp.761-768
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• 2016

Weight bearing is effective during rehabilitation of gait, in the elderly and disabled people. Various training devices using weight bearing function were developed along with treadmill walking; however, no device has been developed in conjunction to walking on the ground. Here, we designed a rail type frame of a gait rehabilitation system for body-weight support (BWS) function, and analyzed its mechanical safety in the static weight bearing condition of a vertical axis. Computational simulations were performed to analyze structure of the driving parts, which are connected with a rail and driving rollers and the lower plate of the BWS. Structural analyses showed the drivers and BWS were safe, when simulated at 135kg weight under static conditions. Thus, this rail type rehabilitation system can be used for gait training of the elderly and disabled.

• Journal of applied mathematics & informatics
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• v.25 no.1_2
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• pp.425-434
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• 2007

We iteratively generate a sequence of measurable mappings and study necessary conditions for its convergence to a random fixed point of random nonexpansive operator. A random fixed point theorem for random nonexpansive operator, relaxing the convexity condition on the underlying space, is also proved. As an application, we obtained random fixed point theorems for Caristi type random operators.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.95-95
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• 2003

In this study, the influences of organic solvent viscosity on absorption properties of split-type micro fiber fabrics is examined with real time absorption measurement device built by our research group recently. And the absorption behavior of these fabrics is analyzed by material, fineness, construction, weight, thickness, and density of fabrics.

• Korean Management Science Review
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• v.11 no.2
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• pp.185-206
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• 1994

This paper investigated, using a flexible approach, the effects of the psychological type of the decision maker and the advanced format of information presentation on decision maker performance in a computer-simulated production game. The current sutdy was guided by a model derived from a general model developed by Chervany, Dickson, and Kozar(1972). The experimental model had two dependent variables; total profit and decision making time. Three independent variables representing the psychological type of the decision maker, the report format, and decision aids were used in this study.