• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2005.11a
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• pp.183-184
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• 2005

Four different coatings deposited using cold spray process were studied with two different powder agglomerating techniques (spray d교 and evaporated powder) and using $TiO_2$ nano-sized powders with and without a 10wt% addition of ZnO. Characterization was performed by SEM, XRD and roughness test. Also the photocatalytic effect of the coatings was evaluated. Although the change of powder preparation techniques and the addition of ZnO into $TiO_2$ did not show appreciable variations in the surface morphology and Anatase phase transformation, it did show influence on the surface roughness of the coating, the highest roughness being found in the coatings made by spray powder prepared method. Regarding the photocatalytic effect it was observed that the using the spray dry coating and the addition of ZnO are promoter of purification at higher rates.

• Journal of Welding and Joining
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• v.20 no.4
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• pp.459-466
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• 2002

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.796-801
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• 2001

During cold operation period, fuel injection system directly contributes the unburned hydrocarbon formation in spark ignition engines. The relationship between injection parameters and HC emission behavior was investigated through a series of experiments. Spray behavior of port fuel injectors was characterized through a quantitative evaluation of mass concentration of liquid fuel by a patternator and PDA. 6-hole injector was found to produce finer spray than single hole one. Using a purpose-built test rig, the wall wetting fuel was measured, which was mostly affected by wall temperature. Varying coolant temperature($20{\sim}80^{\circ}C$), HC emissions were measured in a production engine. With respect to the different types of injectors, HC emission was also measured. In the 6-hole injector application, the engine produced less HC emission in low coolant temperature region. Though it produces much more amount of wetting fuel, it has the advantages of finer atomization quality. In high coolant temperature region, there was little effect between different types of injectors. The control schemes to reduce HC emissions during cold start could be suggested from the findings that the amount of fuel supply and HC emission could be reduced by utilizing fine spray and high intake wall temperature.

• Journal of Powder Materials
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• v.19 no.4
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• pp.317-321
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• 2012

In this study, Cu-5Ni-10Sn(wt%) spinodal alloy was manufactured by gas atomization spray forming, and the microstructural features and mechanical properties of Cu-5Ni-10Sn alloy have been investigated during homogenization, cold working and age-hardening. The spray formed Cu-5Ni-10Sn alloy consisted of an equiaxed microstructure with a mixture of solid solution ${\alpha}$-(CuNiSn) grains and lamellar-structure grains. Homogenization at $800^{\circ}C$ and subsequent rapid quenching formed a uniform solid solution ${\alpha}$-(CuNiSn) phase. Direct aging at $350^{\circ}C$ from the homogenized Cu-5Ni-10Sn alloy promoted the precipitation of finely distributed ${\gamma}$' or ${\gamma}-(Cu,Ni)_3Sn$ phase throughout the matrix, resulting in a significant increase in microhardness and tensile strength. Cold working prior to aging was effective in strengthening Cu-5Ni-10Sn alloy, which gave rise to a maximum tensile strength of 1165 MPa. Subsequent aging treatment slightly reduced the tensile strength to 1000-1100 MPa due to annealing effects.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.8-15
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• 2003

During cold operation, fuel injection in the intake port directly contributes to the unburned hydrocarbon formation in spark ignition engines. The relationship between injection parameters and HC emission behavior was investigated through a series of experiments. Spray behavior of port fuel injectors was characterized through a quantitative evaluation of mass concentration of liquid fuel by a patternator and PDA(Phase-Doppler. Anemometer). A 6-hole injector was found to produce finer spray than single hole injector. Using a purpose-built wall, the wetted fuel was measured, which was mostly affected by wall temperature. HC emissions were measured in a production engine varying coolant temperature$(20~80^{\circ}C)$, also with respect to the different types of injectors. In the 6-hole injector application, the engine produced less HC emission in low coolant temperature region. Though it produces much more amount of wetting fuel, it has the advantages of finer atomization quality. In high coolant temperature region, there was little effect by different types of injectors. The control schemes to reduce HC emissions during cold start could be suggested from the findings that the amount of fuel supply and HC emission could be reduced by utilizing fine spray and high intake wall temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.114-122
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• 1997

Nowadays, gasoline direct injection engines are being commercialized by virtue of improvement in control technology of spray, flow, air fuel ratio. The stratified charge type has the advantage of improving lean limit. The homogeneous type has the advantage of reducing engine-out hydrocabon emissions in the first 30 seconds after a cold start, in addition, improving transient air fuel ratio control. The vaporization and mixing if injected fuel with air has to e completed in a short time and the fuel film in cylinder and on piston has to be minimized. So, the flow and injection should be well controlled. This paper surveyed the spray characteristics of gasoline direct injection by using laser equipment and the combustion characteristics of the single cylinder engine using homogeneousas-mixture type gasoline direct injection.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.47-48
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• 2006

Oridinal thermal spray process has developed into two ways, namely, temperature dominated represented by plasma spraying, and velocity dominated represented by HVOF. It is common for both that the particle materials sprayed are basically in melted or half melted condition. New process has developed recently, that is, Cold Spray and Aerosol Deposition. Particle's heating is limited in CS lower than half of the material's melting point. Moreover, exactly no heating is loaded in AD process. Through the investigation on common feature for these three spraying processes, potential of new material process - Particle Deposition, PD - is considered and proposed.

• Journal of Sericultural and Entomological Science
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• v.39 no.1
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• pp.1-11
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• 1997

In relations to cold acclimation, experiment was carried out to understand the seasonal changes in reserve substances of the mulberry. The shoot barks and leaves of three mulberry varieties(Kaeryangppong, Shinilppong and Yongcheonppong) were sampled, after that their reserve substances were analyzed. The cold hardiness of mulberry was investigated by DTA(Differential Thermal Analysis) method. To increase cold hardiness, gibberellin(100 ppm), kinetin(100 ppm) and Jambi 8 were sprayed on the mulberry leaves. After spraying, falling of the leaves of Yongcheonppong occured earier than the other varities. After the first frost, all of treatments except gibberellin were entirely fallen. Growth regulator extended the leaves fallen. After spraying, water of the shoot barks was not showed difference in the content among the treatments, but amino acid, carbohydrate and soluble protein increased from September to October. Starch content of the shoot barks and leaves was maximum in October, but thereafter decreased during wintering stage. In Shinilppong, Jambi 8 spray increased cold hardiness by 1-2$^{\circ}C$ more than no spray. It was concluded that the cold hardiness of the mulberry in midwinter is closely related to the reserve substances with spraying Jambi 8 on the mulberry leaves.

• Journal of Powder Materials
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• v.19 no.5
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• pp.348-355
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• 2012

Cold spray deposition using Titanium powder was carried out to investigate the effects of powder morphology and powder preheating on the coating properties such as porosity and hardness. The in-flight particle velocity of Ti powder in cold spray process was directly measured using the PIV (particle image velocimetry) equipment. Two types of powders (spherical and irregular ones) were used to manufacture cold sprayed coating layer. The results showed that the irregular morphology particle appeared higher in-flight particle velocity than that of the spherical one under the same process condition. The coating layer using irregular morphology powder represented lower porosity level and higher hardness. Two different preheating conditions (no preheating and preheating at $500^{\circ}C$) were used in the process of cold spraying. The porosity decreased and the hardness increased by conducting preheating at $500^{\circ}C$. It was found that the coating properties using different preheating conditions were dependent not on the particle velocity but on the deformation temperature of particle. The deposition mechanism of particles in cold spray process was also discussed based on the experimental results of in flight-particle velocity.

• Korean Journal of Poultry Science
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• v.24 no.1
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• pp.17-28
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• 1997

This experiment was carried out to investigate the effects of different chilling and packing methods on physico-chernical properties of cold-stored chicken breast and thigh meats. Dehoned chicken breast and thigh meats were chilled either air spray or ice-water immersion method. The chilled meats were either vacuum packed or atmosphere packed, and stored at -2˚C for 1, 3, 7, 11, 15, and 20 days. The pH of both immersion chilled meats and vacuum packed meats were higher than those of their counterparts(P<0.05). The pH of atmosphere packed meats increased as the storage period extended. The moisture contents of vacuum packed meats were remarkably higher than those of atmosphere packed meats. The pH of all treatments decreased as the storage period extended. The shear values of air spray chilled and vacuum packed breast meats were significantly higher than immersion chilled and vacuum packed ones. However, immersion chilled and atmosphere packed breast meats were significantly higher than those of air spray chilled and atmosphere packed breast meats. The shear values of immersion chilled and vacuum packed thigh meats were significantly higher than those of immersion chilled and vacuum packed thigh meats. In atmosphere packed thigh meats, air spray chilling method showed higher shear values than those of immersion chilled thigh meats. In thigh muscle, tenderness values tended to decrease as the storage period extended(P<0.05). Contents of water soluble proteins of vacuum packed and air spray chilled breast and thigh meats were higher than those of their counterparts as the storage period extended(P<0.05). The contents of water soluble proteins significantly decreased as the storage period extended. Salt soluble proteins of atmosphere packed breast and thigh meats were remarkably higher than those of vacuum packed ones(P<0.05). Total lipid contents of atmosphere packed and air spray chilled breast and thigh meats were higher than those of atmosphere packed and immersion chilled meats as the storage period extended. The vacuum packed meats were significantly higher in total lipid contents than those of atmosphere packed meats. The storage period decreased the total lipid contents of cold chicken, Major fatty acids in cold-stored chicken were oleic, palmitic, linoleic and stearic acids, regardless of chilling method. Unsaturated fatty acids of all treatments decreased, but saturated fatty acids increased as the storage period extended.