• Proceedings of the KSME Conference
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• 2003.11a
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• pp.574-579
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• 2003

The present study addresses an analytical investigation to understand the characteristics of gas flow in the High-Velocity Oxy-Fuel(HVOF) thermal spray gun. One-dimensional analysis is extended to involve the effects of the wall friction and powder particle diameter. From the present analysis it is well known that the flow characteristics inside and outside the thermal spray gun is varied depending on the combustion chamber pressure. The thermal spray gun flow is characterized by six different patterns. The powder particle size and wall friction significantly influence the powder particle velocity. The particle velocity decreases with an increase in the powder particle size. This implies that the combustion chamber pressure should be increased to achieve a higher velocity of the powder particle.

• International Journal of Industrial Entomology and Biomaterials
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• v.37 no.2
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• pp.105-108
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• 2018

Recently matured silkworm powder was developed by RDA. In this study, the effect of pulverizing method on the particle size of matured silkworm powder was examined. FESEM was performed to observe the morphology and to measure the particle size of silkworm powder. Particle morphology of air-jet mill pulverized powder was round and smooth, however, those of roller-mill and hammer-mill pulverized mature silkworm was more harsh and square. Particle size was varied with pulverizing technique as follows; $1.1{\mu}m$ (air-jet mill), $10{\mu}m$ (roller mill), and $120{\mu}m$ (hammer mill), respectively. A proximate analysis results of air-jet mill powder showed that crude protein, crude lipid, crude fiber, and ash was 73%, 12%, 1.95%, and 3.4%, respectively. According to our results, air-jet mell technique might be used to make a tiny matured silkworm powder.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.395-396
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• 2006

To manufacture a flange for a compressor with a relief groove by using powder metallurgy in order to prevent deformation to the compressor in operation, powder material for the flange is charged into a mold; an ablative member having a melting point lower than that of the powder material is positioned at a place where a relief groove is to be formed; the flange is formed by compressing the powder material and the ablative member; and the formed flange is sintered at a temperature between the melting point of the powder material and the ablative member so as to melt and remove the ablative member. It made according to the new method has more excellent strength and airtight property than the conventional one. It is analyzed that the ablative member is melted and penetrated into the flange structure during the sintering process, which results in improvement of the airtight property and increase of the strength.

• Korean journal of food and cookery science
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• v.30 no.6
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• pp.726-734
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• 2014

The purpose of this study was to examine the qualities of muffins made with 0, 2, 4, 6, and 8% Corni fructus powder. The height of the muffins did not significantly differ between the sample groups; however, the weight of the control group was higher than that of the test samples containing Corni fructus powder. The volume and specific loaf volume of muffins decreased with the addition of Corni fructus powder. The baking loss of the samples containing Corni fructus powder was also higher than that of the control group. The moisture content of the control group was 19.88%, whereas that of the test samples ranged from 16.72~21.01%. The pH of batters and muffins of the test samples were lower than those of the control group. For DPPH radical scavenging activity, the control group measured 11.46%, whereas the test samples ranged from 22.63~53.33%. The L and b values of the crust and crumbs decreased, but the a value was increased significantly by the addition of Corni fructus powder. Examination of the textural properties revealed the hardness, gumminess and brittleness of muffins containing Corni fructus powder were significantly higher than those of the control group. In term of overall preference, the sensory evaluation scores of groups containing 2% and 4% of Corni fructus powder did not show significant differences compared to the control group. Based on the above results, using Corni fructus powder at less than 4% would be appropriate for making muffins.

• Journal of Powder Materials
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• v.21 no.1
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• pp.44-49
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• 2014

In this study, nanocrystalline nickel powders were cold compacted by a dynamic compaction method using a single-stage gas gun system. A bending test was conducted to measure the bonding strengths of the compacted regions and microstructures of the specimen were analyzed using a scanning electron microscopy. The specimen was separated into two parts by a horizontal crack after compaction. Density test shows that the powder compaction occurred only in the upper part of the specimen. Brittle fracture was occurred during the bending test of the compact sample. Dispersion of shock energy due to spalling highly affected the bonding status of the nanocrystalline nickel powder.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.11a
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• pp.25-25
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• 2004

• Journal of Powder Materials
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• v.21 no.3
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• pp.196-201
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• 2014

In this study, nanocrystalline Cu-Ni bulk materials with various compositions were cold compacted by a shock compaction method using a single-stage gas gun system. Since the oxide layers on powder surface disturbs bonding between powder particles during the shock compaction process, each nanopowder was hydrogen-reduced to remove the oxide layers. X-ray peak analysis shows that hydrogen reduction successfully removed the oxide layers from the nano powders. For the shock compaction process, mixed powder samples with various compositions were prepared using a roller mixer. After the shock compaction process, the density of specimens increased up to 95% of the relative density. Longitudinal cross-sections of the shock compacted specimen demonstrates that a boundary between two powders are clearly distinguished and agglomerated powder particles remained in the compacted bulk. Internal crack tended to decrease with an increase in volumetric ratio of nano Cu powders in compacted bulk, showing that nano Cu powders has a higher coherency than nano Ni powders. On the other hand, hardness results are dominated by volume fraction of the nano Ni powder. The crystalline size of the shock compacted bulk materials was greatly reduced from the initial powder crystalline size since the shock wave severely deformed the powders.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1102-1103
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• 2006

The pretreatment for substrate was carried out in change of gun pressure of $0.5\sim3.5$ bar using wet blasting. The size of $Al_2O_3$ powder was about $50{\sim}150{\mu}m$. As the results, the surface roughness of cemented carbide substrate was improved with increment of gun pressure of wet blasting. A new surface layer was formed and Co particles were uniformly distributed over the entire surface after pretreatment. The adhesion of the pretreated substrate in same PVD-TiAlN film was improved and in approximately $Ra=90\sim120\;nm$ shown the best adhesion value.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.19-20
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• 2014

This study is to find out the tensile strength and bonding strength of VAE powder as a preliminary study for the application of the powder to the high strength concrete. The result of the study showed that the compressive strength decreases when more polymers is put into the concrete. On the other hand, it showed that the tensile strength and the bonding strength get improved when the more polymers are put into the concrete. Especially in case of the mixture for high strength concrete, it was found out that more strength is produced than the ordinary concrete.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.04a
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• pp.76-76
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• 2006