• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.04a
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• pp.50-50
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• 2006

• Journal of Powder Materials
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• v.18 no.2
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• pp.168-171
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• 2011

We investigate grain growth behavior of poly-crystalline Mg sheet having strong basal fiber texture using phase field model for grain growth and micro-elasticity. Strong initial basal texture was maintained when external load was not imposed, but was weaken when external biaxial strain was imposed. Elastic interaction between elastic anisotropy of Mg grain and external load is the reason why texture evolution occurs.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.785-786
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• 2009

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.311-313
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• 2004

WC-12-17%Co powders with nano- and micro-structures were deposited by cold spray process using nitrogen and helium gases. The results show that there is no detrimental phase transformation and/or decarburization of WC by cold spray deposition as expected. It is also observed that nano-sized WC in the feedstock powder is maintained in the cold spray deposition. It is demonstrated that it is possible to fabricate the nano-structured WC-Co coating with low porosity and very high hardness (-2050 HV) by cold spray deposition with reasonable powder preheating.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1832-1835
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• 2003

This paper suggests the selective ultra precision polishing techniques for micro die and mold parts using magnetic-assisted machining. Fabrication of magnetic abrasive particle and their polishing performance are key technology at ultra precision polishing process of micro parts. Conventional magnetic abrasives have disadvantages. which are missing of abrasive particle and inequality between magnetic particle and abrasive particle. So, bonded magnetic abrasive particles are fabricated by several method. For example, plasma melting and direct bonding. Ferrite and carbonyl iron powder are used as magnetic particle where silicon carbide and Al$_2$O$_3$ are abrasive particle. Developed particles are analyzed using measurement device such as SEM. Possibility of magnetic abrasive and polishing performance of this magnetic abrasive particles also have been investigated. After polishing, surface roughness of workpiece is reduced from 2.927 $\mu\textrm{m}$ Rmax to 0.453 $\mu\textrm{m}$ Rmax.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.145-149
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• 2023

In this study, the spectrum changes induced from the doping of phosphor micro particles in a twist nematic liquid crystal cell was observed. The experimental results show that the achromatic transmission can be observed with a proper driving condition, which may be applied to the design of an achromatic liquid crystal device. In this paper, we tried to figure out the spectrum changes induced from the doping of phosphor micro particles. The experimental result of the phosphor powder doped twist nematic liquid crystal cell shows that the achromatic transmission and the wavelength linearly dependent transmission both can be observed with some proper driving conditions, respectively. The result is useful on developing an achromatic liquid crystal device and it can be applied for Vihicle lamp.

• Journal of Powder Materials
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• v.20 no.1
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• pp.48-52
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• 2013

A study of oxidation kinetic of Fe-36Ni alloy has been investigated using thermogravimetric apparatus (TGA) in an attempt to define the basic mechanism over a range of temperature of 400 to $1000^{\circ}C$ and finally to fabricate its powder. The oxidation rate was increased with increasing temperature and oxidation behavior of the alloy followed a parabolic rate law at elevated temperature. Temperature dependence of the reaction rate was determined with Arrhenius-type equation and activation energy was calculated to be 106.49 kJ/mol. Based on the kinetic data and micro-structure examination, oxidation mechanism was revealed that iron ions and electrons might migrate outward along grain boundaries and oxygen anion diffused inward through a spinel structure, $(Ni,Fe)_3O_4$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.108-111
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• 2001

YBCO HTS thick films coated using powder, Y$_2$O$_3$+L, quenched over 1200$^{\circ}C$ was studied. Quenched powder was crushed and mixed well in order to obtain uniformly dispersed Y2ll. Also, the powder was prepared with various condition in other to acquire optimum micro structure. As a result, it was found that the quenched sample on 1300$^{\circ}C$, holding time of 30min, has a bettor characteristic than other sample. On the other hand, the effect of film thickness was investigated. We concluded that the initiate film thickness has to be over 150$\mu\textrm{m}$. Especially, it was found that the film coated over 3 times with 50$\mu\textrm{m}$ m was best quality.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1350-1356
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• 2006

The old technique of sandblasting which has been used for paint or scale removing, deburring and glass decorating has recently been developed into a powder blasting technique for brittle materials, capable of producing micro structures larger than $100{\mu}m$. In this paper, The surface characteristics of powder blasted glass surface were tested under different blasting parameter. Finally, we proposed a predictive model for powder blasting process using a neural network. A detailed analysis of the simulation results has been carried out and compared with experimental results.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.839-840
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• 2006

Sintering behavior of the Fe-0.8Mn-0.5C powder system was studied on the specimens with a density of ${\sim}7.0g/cc$ sintered at $1120^{\circ}C$ for 30 min in a gas mixture of $7%H_2/93%N_2$ with the inlet dew point of $-60^{\circ}C$. During the atmosphere monitoring ($CO/CO_2$-content and dew point) was showed, that carbothermical reduction occurs in two different temperature ranges; three peaks of dew point profile also can be distinguished during sintering cycle as well. Following sintering the Mn-content distribution and microstructures around the Mn-source were micro-analytical evaluated; the results showed that manganese travels through porous iron matrix up to ${\sim}60{\mu}m$.