• Korean Journal of Poultry Science
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• v.34 no.3
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• pp.157-163
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• 2007

To examine the effects of dietary organic selenium and vitamin E supplementation on egg production, egg weight, daily egg mass, feed intake, feed conversion, egg quality, lipid-soluble antioxidative capacity (ACL) in egg yolk, and selenium retention of egg in laying hens, Hy-Line laying hens of 77 wk old were replaced in the individual cage for 12 week. A corn-soybean meal based diet was supplemented with 0 (control), vitamin E 100 IU/kg and the combination of 0.9 ppm Se from selenium yeast (SY) and vitamin E 50, 100 and 150 IU/kg. Egg production and daily egg mass were significantly increased (P<0.05) in supplemental vitamin E 100 IU, and 0.9 ppm SY + vitamin E 50 IU than control for the whole experimental period. However, feed intake and feed conversion were not affected by supplemental vitamin E and SY. Haugh unit was significantly (P<0.05) higher in supplemental vitamin E 100 IU and 0.9 ppm SY + vitamin E 50 IU than control, 0.9 ppm SY + vitamin E 100 and 0.9 ppm SY + 150 IU in week 5. Haugh unit of the eggs during storage decreased significantly(P<0.05) from day 1 to day 11. However, Haugh units of the eggs from 0.9 ppm SY + vitamin E 150 IU treated groups did not decreased significantly until day 5. Yolk color was significantly (P<0.05) higher in 0.9 ppm SY + vitamin E 50 and 0.9 ppm SY + 100 IU than other treatment groups in week 1. Selenium concentrations of egg were significantly increased (P<0.05) in 0.9 ppm SY + vitamin E than control and vitamin E 100 IU groups. Lipid-soluble antioxidative capacity (ACL) in egg yolk was significantly (P<0.05) higher in supplemental combination of 0.9 ppm SY + vitamin E 150 IU when compared to those of other treatment groups.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.6
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• pp.57-63
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• 2017

In this study, the fundamental test for drag reduction is carried out by using a plasma generator. Fundamental test setup is constructed of visualization and drag measurement system. The schlieren technique is used to visualize the plasma counterflow in supersonic flow. The penetration of the plasma jet and the change of the flow structure are observed through visualization results. Load cell is used to confirm possibility of drag reduction. Results show that drag was reduced by 6.2% using plasma jet in supersonic flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.965-973
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• 2010

Numerical analysis has been carried out to investigate the heat transfer characteristics of a plate heat exchanger. The multi-cell models with inlet part and outlet part are used for performing numerical simulation. The plate heat exchanger is characterized by chevron angle of $15^{\circ}$, corrugation pitch of 24mm and corrugation height 6~12mm. The length of the inlet-part considered in the analysis ranges from 24.8 to 124mm and Reynolds numbers range from 1,000 to 10,000. The correlations such as friction factor and Colburn factor are compared with previous experimental data. The results can be utilized for designing the plate heat exchanger.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.471-479
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• 2010

The adiabatic two-phase flow in single rectangular microchannels was studied for different aspect ratios. The working fluids were liquid water and nitrogen gas. The hydraulic diameters of the rectangular microchannels were 490, 322, and $143\;{\mu}m$, and the widths of the microchannels were around $500\;{\mu}m$. The two-phase flow pattern was visualized using a high-speed camera and a long-distance microscope. This study was focused on bubble flow regimes. From the visualized images, the bubble velocity, bubble length, number of bubbles, and void fraction were evaluated. Further, the pressure drop in a single bubble was evaluated by using a unit cell model. The bubble velocity is proportional to the superficial velocity. Further, the relationship between the void fraction and the volumetric quality is linear. The pressure drop in a single elongated bubble is strongly related to the aspect ratio. Finally, the new correlation about the pressure drop of a single elongated bubble in the rectangular microchannel was proposed.

• Journal of Internet Computing and Services
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• v.23 no.5
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• pp.25-31
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• 2022

In ultra dense networks (UDNs), macro user equipments (MUEs) have significant interference from small-cell access points (SAPs) since a number of SAPs are deployed in the coverage of macro base stations of 5G mobile communication systems. In this paper, we propose a dynamic channel assignment scheme to increase the performance of MUEs for the uplink of UDNs even though the number of SAPs is increased. The target of the proposed dynamic channel assignment scheme is that the signal-to-interference and noise ratio (SINR) of MUEs is above a given SINR threshold assigning different subchannels to SUEs from those of MUEs. Simulation results show that the proposed dynamic channel assignment scheme outperforms others in terms of the mean MUE capacity even though the mean SUE capacity is decreased a little lower.

• Korean Journal of Poultry Science
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• v.34 no.2
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• pp.143-149
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• 2007

The experiment was conducted to examine the effects of dietary organic selenium and vitamin E on weight gain, feed intake, feed conversion, and selenium retention in meat of broiler chickens. For each growth phase, the basal diet was supplemented with 0 (control), vitamin E 150 IU/kg and the combination of 1.2 ppm Se from selenium yeast (SY) and vitamin E 100, 150, 200 and 300 IU/kg. Weight gain was significantly higher in supplemental control and vitamin E 150 compared to the combination of 1.2 ppm SY and vitamin E 150 IU during day 1 to 21. Feed intake significantly(P<0.05) increased in supplemental vitamin E 150 compared to the combination of 1.2 ppm SY and vitamin E 150 and 200 IU during day 1 to 21. Feed intake was significantly(P<0.05) higher in control compared to that of combination of 1.2 ppm SY and vitamin E 200 IU during day 21 to 35. However feed conversion was not affected in supplemental vitamin E and SY during day 1 to 35. Selenium concentrations of breast muscle and liver tissue significantly increased (P<0.05) in supplemental combination of 1.2 ppm SY and vitamin E compared to the control and vitamin E 150 IU. TBARS of control and vitamin E 150 IU were significantly (P<0.05) higher in day 3 than day 1, but the combination of Se 1.2 ppm and vitamin E of TBARS had no difference during day 1 to 3. TBARS in day 3 was significantly (P<0.05) lower in supplemental combination of Se 1.2 ppm and vitamin E than control and vitamin E 150 IU.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.414-420
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• 2011

Thermal stress analysis of a planar anode-supported SOFC considering electrochemical reactions has been performed under operating conditions where average current density varies from 0 to 2000 $A/m^2$. For the case of the 2000 $A/m^2$ operating condition, Structural stress analysis based on the temperature distributions obtained from the CFD analysis of the unit cell has also been done. From this one way Fluid-Structure Interaction(FSI) analysis, Maximum Von-Mises stress under negligible temperature gradient fields occurs when cell components are perfectly bonded. The maximum stress of the electrolyte, cathode and anode in a unit cell SOFC is 262.58MPa, 28.55MPa and 15.1MPa respectively. The maximum thermal stress is critically dependent on static friction coefficient.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.403-408
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• 2016

Lithium-ion batteries are commonly employed in hybrid electric vehicles (HEVs), and achieving high energy density in the battery has been one of the most critical issues in the automotive industry. Because liquid cooling containing antifreeze is important in automotive batteries to enable cold starts, an effective geometric configuration for high-cooling performance should be carefully investigated. Battery cooling with antifreeze has also been considered to realize successful cold starts. In this article, we theoretically investigate a specific property of an antifreeze cooling battery system, and we perform numerical modeling to satisfy the required thermal specifications. Because a typical battery system in HEVs consists of multiple stacked battery cells, the cooling performance is determined mainly by the special properties of antifreeze in the coolant passage, which dissipates heat generated from the battery cells. We propose that the required cooling performance can be realized by performing numerical simulations of different geometric configurations for battery cooling. Furthermore, we perform a theoretical analysis as a design guideline to optimize the cooling performance with minimum power consumption by the cooling pump.

• Journal of Navigation and Port Research
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• v.36 no.5
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• pp.357-361
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• 2012

Anemometer is a meteorological instrument that measures wind direction and wind speed in real time, and is mounted to the cranes that are used at ports, shipbuilding yards, off-shore structure, or construction sites that are influenced by wind, and it is used in conjunction with the safety system. Load cell-type anemometer measures the wind direction through the ratio of load between 4 positions by mounting the thin plate to 4 load cells, and measures wind velocity through the summation of loads. In this study, we compared and analyzed the results in the theoretic approach, analytic approach and experimental approach to derive the correlation between load ratio and wind direction. Wind direction was selected as the design variable, and selected 9 wind direction conditions from $0^{\circ}{\sim}90^{\circ}$ with $11.25^{\circ}$ space for analysis, and 10 wind direction conditions with $10^{\circ}$ space for experiment.

• Journal of the Korean Association of Geographic Information Studies
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• v.6 no.2
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• pp.65-79
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• 2003

In this study GIS based pre- and post-processing tool for the Visual MODFLOW that is specific software to model groundwater flow is developed. This tool not only makes input data scientifically but also manages input and output data in terms of the groundwater flow analysis. In addition it can storage project products systematically into Oracle database. The most characteristic figure of this processing tool is to provide the module, which automatically or semi automatically develops various grid cell sizes using GIS ArcView and also produces DXF files reflecting various boundary conditions in the modeling zone. In particular, eminences of this research are to create 3 dimensional hydrogeological structures with 2 dimensional GIS ArcView and to conduct pre- and post- processing along with same topology and data format of the MODFLOW.