• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.143-146
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• 2002

Mg alloy is the lightest material of structural materials and is noticed for lightweight automotive parts because of excellent castability, superior ductility and damping capacity than Al alloy. But Mg Alloy is poor corrosion resistance and high temperature creep properties. In this study, Mg Matrix Composites were fabricated by squeeze casting method to improve high temperature creep properties and damping capacity. Hybrid Mg composites reinforced with Alborex, graphite particle, and SiCp was improved creep properties and damping capacity compared with Mg alloy. Compared to the length ($9\mu\textrm{m}, 27\mu\textrm{m}, 45\mu\textrm{m} etc.$), Hybrid Mg composites reinforced with SiCp, one of the most superior of the length and Alborex were more superior than those reinforced with graphite particle and Alborex in mechanical properties, creep characteristics, and damping capacity, etc.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3695-3705
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• 1996

We designed the hot wind tunnel to reproduce the conditions of utility boiler and carried out its performance test, in order to investigate the particulate two-phase flow behaviour, the fouling and heat transfer characteristics to the heat exchanger. The hot wind tunnel introduces the control system to control the temperature in the test section. The particle is injected into the hot gas stream. The fouling probe (cylindrical tube) is positioned normal to the particulate gas-particle two-phase flow and cooled by the air. The temperature of gas and cooling air, and temperature in the fouling probe are measured as a function of time, giving the local and averaged heat transfer and fouling factor. The shape of particulate deposition adhered to the fouling probe is also observed.

• Journal of Korea Foundry Society
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• v.23 no.3
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• pp.130-136
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• 2003

Rheocasting of AZ91D magnesium alloys yielded the microstructure consisted of the spherical primary particles in the matrix which is different from conventional casting. Rheocast ingots were produced under various processing conditions using batch type rheocaster. Morphology of primary particles was changed from rosette-shape to spherical shape with increasing stirring rate$(V_s)$ and decreasing isothermal stirring temperature$(T_s)$. With increasing $V_s$, more effective shearing between the particles occurred rather than the agglomeration and clustering, so the primary particle size decreased. But with decreasing $T_s$, primary particle size increased mainly due to sintering and partially Ostwald ripening. The sphericity of primary particles increased with increasing $V_s$ and decreasing $T_s$ due to enhanced abrasion among the primary particles. The uniformity of primary particle size increased with increasing Vs and $T_s$.

• Macromolecular Research
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• v.10 no.3
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• pp.140-144
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• 2002

Dispersion polymerization of acrylamide was carried out in the media of methyl alcohol/$H_2O$ mixtures using hydroxypropyl cellulose and ammonium persulfate as steric stabilizer and initiator, respectively. The effects of concentrations of initiator and steric stabilizer, amount of monomer, polymerization temperature, methyl alcohol/$H_2O$ ratio, and purification of monomer and nitrogen purge on the particle size of the latices and molecular weight of the polymers were investigated. The average particle diameter increased with increasing concentration of initiator, water content in methyl alcohol/$H_2O$ media, and polymerization temperature, but decreased with monomer and stabilizer concentrations. The viscosity average molecular weight increased with increasing concentrations of monomer, steric stabilizer, and water content in dispersion media, but decreased with initiator concentration and polymerization temperature. The PAM polymers prepared with the purified monomer and the nitrogen purging before the reaction showed the highest molecular weight.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.1
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• pp.175-183
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• 1994

To investigate thermophoretic effect on particle deposition, average deposition velocity toward a horizontal wafer surface in vertical airflow is measured keeping the wafer surface temperature different from the surrounding air temperature. In the present measurement, the temperature difference is maintained in the range from -10 to $4^{\circ}$ C Polystyrene latex (PSL) spheres of diameter between 0.3 and 0.8 .mu.m are used for the experiment. The number of particles deposited on a wafer surface is estimated from the measurements using a wafer surface scanner (PMS SAS-3600). Experimental data are compared with prediction model results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.11
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• pp.3063-3071
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• 1995

An experimental study has been carried out for the heat transfer and particle deposition during the Outside Vapor Deposition process. The surface temperatures of deposited layers, and the rates, efficiencies and porosities of particle deposition were measured. It is shown that the axial variation of the surface temperature can be assumed to be quasi-steady and that as the traversing speed of burner is increased, the deposition rate, efficiency and porosity increase due to the decreased surface temperature. As the flow rate of the chemicals is increased, both the thickness of deposition layers and the surface temperature increase. Deposition rate also increases, however, deposition efficiency decreases for tests done. Later passes in early deposition stage result in higher surface temperatures due to increased thickness of porous deposited layers, which cause the deposition rate, efficiency, and porosity to decrease.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.110-116
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• 2006

A new measurement technique based on a two-color pyrometry and modulated LII signals to measure local soot particle temperatures has been proposed and examined experimentally. The theoretical review suggests that modulated LII signals of soot particles is suitable for a two-color pyrometry as long as the temperature increase due to laser heating remains relatively small. The modulated LII signals from ethylene and propylene diffusion flames were simultaneously measured at 550 and 750 nm by a dual measurement system that consists of optical fibers, PMT and lock-in amps. The local soot particle temperatures of diffusion flames could be obtained using a two-color pyrometry and modulated LII signal based new technique.

• Journal of Powder Materials
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• v.11 no.1
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• pp.43-49
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• 2004

The electrical and thermal conductivity of W-Cu composites were investigated as a function of the W-particle size and W-W contiguity. Powder mixtures were prepared by ball milling or mechanical alloying process, and then sintered at various temperatures. The electrical conductivity of sintered composite was increased with decreasing W grain size. Dependence of electrical conductivity on the W grain size was explained by the W-W contiguity concept. The thermal conductivity was increased with increasing the temperature up to $600^{\circ}C$ but decreased at the temperature above $600^{\circ}C$ Also, thermal conductivity value was influenced by the W particle size. Change of thermal conductivity in W-Cu composites was discussed based on the observed microstructural characteristics and theoretical considerations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.548-551
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• 1999

The cure characteristics of metal particle filled DGEBA/MDA/SN/ zeolite epoxy resin composite system for EMI shielding were investigated by dynamic DSC run method and FT-lR spectroscopy. As the heating rate increased, the peak temperature on dynamic DSC curve increased because of the rapid cure reaction. From the straight line of the Kissinger plot, the curing reaction activation energy and pre-exponential factor could be obtained. As the post-curing time at 15$0^{\circ}C$ increased, the glass increased the glass transition temperature or the thermal stability increased. When the post curing time is too long, the system filled with metallic Al particle can be thermally oxidized by the catalytic reaction of metal filler and the thermal stability of the composite for the EMI shielding application may be decreased.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.45-48
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• 2007

This study investigates mechanical properties of the concrete using coarse particle cement which is manufactured by the classifying process. The variable factors are 3 types of W/C such as 40, 50, and 60% and 5types of the replacement of the coarse particle cement such as 0, 25, 50, 75, and 100%. As the results, amount of SP agent to secure the target fluidity is gradually declined in accordance with increasing CC replacement. There is no special tendency for target air content, but setting time is delayed according to increasing CC content. The peak of the simple adiabatic temperature rise is gradually decreased in accordance with increasing CC content, and approach time to peak is slightly delayed. The compressive strength is comparatively delayed.