• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.4
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• pp.201-208
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• 2000

The reduction of NO by hydrocarbons was investigated over Cu/Al$_2$O$_3$catalysts using a stainless steel flow reactor under highly oxidising diesel exhaust conditions(up to 15%). Three different Cu loadings(1,5 and 10wt.%) on an $Al_2$O$_3$support were prepared and characterized using spectroscopic techniques. The catalytic activity tests show that different Cu loadings as well as temperature, oxygen, and hydrocarbon concentration levels significantly influence the NO reduction. Increasing Cu loadings up to 5 and 10wt.% decreases the catalytic activities for NO reduction due to the formation of a bulk crystalline CuO phase, as observed from XRD and SEM images. In particular, the visualization of the copper dispersion on the surface using the SEM-BEI technique provides information on the extent of copper saturation, particle size, and the effects on NO reduction. However, the lower Cu loading(1 wt.%) increases the catalytic activity with a temperature window of 720-810K, thereby favoring the formation of well dispersed isolated Cu species, e.g. Cu(sup)2+ ions, which is related to selective NO reduction. The effects of other reaction parameters, such as oxygen, the hydrocarbon level and type, and byproduct emissions are further discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.236.1-236.1
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• 2014

Compounds of Ga, such as gallium oxide (Ga2O3) and gallium nitride (GaN), are of interest due to its unique properties in semiconductor application. In particular, GaN has the potentially application for optoelectronic device such as light-emitting diodes (LEDs) and laser diodes (LDs) [1]. Nanoparticle is an interesting material due to its unique properties compared to the bulk equivalents. In this report, we develop a synthesizing method for gallium nitride nanoparticle using non-thermal plasma. For gallium source, the gallium is heated by thermal conduction of tungsten boat which is heated by eddy current induced from RF current in antenna. Nitrogen source for nanoparticle synthesis are from inductively coupled plasma with N2 gas. The synthesized nano particles are analyzed using field-emission scanning microscope (FESEM), transmission electron microscope (TEM) and x-ray photoelectron spectroscopy (XPS). The synthesized particles are investigated and discussed in wide range of experiment conditions such as flow rate, pressure and RF power.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.151-154
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• 2003

AlN/Al/SiO$_2$/Si thin films for application to FBAR(Film Bulk Acoustic Resonator) devices were prepared by FTS(Facing Targets sputtering system) apparatus which provides a stable discharge at low gas pressures and can deposit high quality thin films because of the substrate located apart from the plasma. The AlN thin films were deposited on a $SiO_2(1{\mu}m)/Si(100)$ substrate using an Al bottom electrode. The process parameters were fixed such as sputering power of 200W, working pressures of 1mTorr and AlN thin film thickness of 800nm, respectively and crytallographic characteristics of AlN thin films were investigated as a function of $N_2$ gas flow rate$[N_2/(N_2+Ar)]$. Thickness of AlN thin films were measured by $\alpha$-step, the crystallographic characteristics and c-axis preferred orientation were evaluated by XRD.

• Journal of Power System Engineering
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• v.18 no.3
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• pp.51-58
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• 2014

Injection molding simulation provided optimized design results by analyzing quality problems while the product is in assembly or in the process of manufacturing with make automobile plastics. Frequent change of design, change of injection molding, repetition of test injection which was held in the old way can now be stopped. And quality upgrade is expected instead. This report deals with the effect which the position of injection molding automobile console gate and number has on product quality including pressure at end of fill, bulk temperature at end of fill, shear stress of end of fill, residual stress at post filling end, product weld lines and warpage results. Simpoe-Mold simulates the complete manufacturing process of plastic injected parts, from filling to warpage. Simpoe-Mold users, whether they are product designers, mold makers or part manufacturers, can identify early into the design stage potential manufacturing problems, study alternative solutions and directly assess the impact of such part modification, whatever the complexity and geometry of such parts, shell part as plain solid parts.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.266-273
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• 2002

Milli-structure components are classified as a component group whose size is between macro and micro scales, that is, about less than 20mm and larger than 1mm. The bending of these components of thin sheets has a typical phenomenon of bulk deformation because of the forming size. The recent trend towards miniaturization causes an increased demand for parts with very small dimensions. The conceptual miniature bending process enables the production of such parts with high productivity and accuracy. The stress values of the flow curve decrease with miniaturization, which means that coarse grained materials show a higher resistance against deformation, when the grain size is in the range of the sheet thickness. In this paper, a new numerical approach is proposed to simulate intergranular milli-structure in forming by the finite element method. The grain element and grain boundary element are introduced to simulate the milli-structure of strip in the bending. The grain element is used to analyze the deformation of individual grain while the grain boundary element is for the investigation on the movement of the grain boundary. Also, the result of the finite element analysis is confirmed by a series of milli-sized forming experiments.

• Journal of Animal Environmental Science
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• v.20 no.1
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• pp.15-20
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• 2014

The present study was conducted to develop a milk filtering system for decreasing somatic cell count (SCC) in bulk tank milk. The pore sizes of the filter were 0.1, 0.3, 0.4, 0.5 and $0.8{\mu}m$. The rate of SCC reduction of $1^{st}$ grade milk on $0.1{\mu}m$ filter was 76% and significantly higher than other treatments. The rates of SCC reduction for 0.3, 0.4, 0.5 and $0.8{\mu}m$ were 35, 32, 18 and 6.4%, respectively. The effects of the milk filtering system on bacterial count and milk fat content were minimal. The milk flow rates per minute between the filter sizes were similar. But discharge pressures were increased as the pore size of the filter decreased. In conclusion, Considering the rate of SCC reduction, discharge pressure and cost, $0.4{\mu}m$ filter could be recommended.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.3
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• pp.90-98
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• 2006

The Heated Tube Facility(HIF) was fabricated to identify the forced convective heat transfer and the cooling characteristic for the hydrocarbon fuel(Jet A-1), which is used for the coolant of the regenerative cooling system. The forced convective heat transfer coefficient was calculated from the measured coolant and tube surface temperature. In case of using the Jet A-1, the maximum heat flux which the coolant can absorb was identified by determining the critical wall temperature generating the burnout on the fixed flow condition. The inlet bulk-temperature of the coolant has a direct influence on the forced convective heat transfer characteristic.

• Polymer(Korea)
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• v.26 no.4
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• pp.439-444
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• 2002

Several monomeric benzilidene anhydrides (2a~d) haying n-alkyloxy groups with various n-alkyl chain lengths were prepared by Stobbe condensation of diethyl succinate with 4-(n-alkyloxy)benzaldehyde (1a,b) followed by hydrolysis by the succinates and cyclodehydration of the benzilidenated succinic acids. Configurational isomerism of the monomer was investigated by spectroscopic means. It was found that monomers (2a~d) exist in (Z,Z)-isomeric structure. Polymerization was carried out in bulk at 150~$210^{\circ}C$ range in nitrogen flow. The chemical structure and thermal properties of the polymers were characterized by spectroscopic means, TGA and DSC. Their properties highly depended on their chemical structures in accordance with a side chain length.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2479-2490
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• 2020

We performed experiments to measure a single-phase upward flow in a 5 × 5 rod bundle with spacer grids using a particle image velocimetry, focusing on the crossflow. The Reynolds number based on the hydraulic diameter and the bulk velocity is 10,000. The ratio of pitch between rods and rod diameter is 1.4 and spacer grid is installed periodically. The turbulence in the rod bundle results from the combination of a forced mixing and natural mixing. The forced mixing by the spacer grid persists up to 10D_h from the spacer grid, while the natural mixing is attributed to the crossflow between adjacent subchannels. The combined effects contribute to a sinusoidal distribution of the time-averaged stream-wise velocity along the lateral direction, which is relatively weak right behind the spacer grid as well as in the gap. The streamwise and lateral turbulence intensities are stronger right behind the spacer grid and in the gap. Based on these findings, we newly defined a modified mixing coefficient as the ratio of the lateral turbulence intensity to the time-averaged streamwise velocity, which shows a spatial variation. Finally, we compared the developed model with the measured data, which shows a good agreement with each other.

• Journal of Environmental Science International
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• v.24 no.6
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• pp.721-729
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• 2015

Surface heat balance of the Gangjeong-Goryung Reservoir is analyzed for 12-17 August 2013. Each flux elements at the water surface is derived from the special field observations with application of an aerodynamical bulk method for the turbulent heat fluxes and empirical formulae for the radiation heat fluxes. The rate of heat storage in the reservoir is estimated by using estimated by surface heating rate and the vertical water temperature data. The flux divergence of heat transport is estimated as a residual. The features of the surface heat balance are almost decided by the latent heat flux and the solar radiation flux. On average for 12-17 August 2014 in the Gangjeong- Goryung Reservoir, if one defines the insolation at the water surface as 100 %, 94 % is absorbed in the reservoir; thereafter the reservoir loses about 30~50% by sensible heat, latent heat and net long-wave radiation. The residue of 50~80 % raises the water temperature in the reservoir or transported away by the river flow during the daytime.