• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.269-274
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• 2004

As next generation display, TFT LCD gets into the spotlight, and the bigger glass size is required. Currently, its display size is 1500 mm by 1870 mm at the six generation comparing with 300mm by 400 mm at the first one and the size is increasing continuously, which cause the difficulties to apply the cleaning operation including the general brush cleaning. In this study, water-jet cleaning operation has been introduced, which spent the less water them other cleaning methods. Throughout the experiment, is has been found the possible damage of the declined cell and the variation of the tilt bias angle depending upon the increasing time. In addition, the simulation predicts the glass bending of the display.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.5
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• pp.36-41
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• 1999

Although the problems of defects and nonmetallic inclusion in metal fatigue are very complicated it is particularly important to view these problems from the perspective that defects and inclusions are virtually equivalent to small cracks. This concept will help us to understand various fatigue phenomena caused by graphite of Ductile cast iron. Therefore in this study different ferrite-pearlite matrix structure and pheroidal ratio of graphite of 70%, 80% and 90% GCD40 , GCD45-2 series have been carried out rotary bending fatigue test estimated the maxi-mum size of graphite investigated correlation. It was concluded as follows : (1) in ductile cast iron which have various spheroidal ratio of graphite the fatigue limit C series of 90% spheroidal ratio of graphite is the highest. While A series of 70% spheroidal ratio of graphite is the lowest (2) fatigue limit was predicted by vickers hardness(Hv) of matrix {{{{ SQRT {area } }}}} of maximum size graphite inputting Murakami and Endo's formula.

• Macromolecular Research
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• v.12 no.2
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• pp.240-245
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• 2004

Monodisperse PMMA micro spheres are prepared by means of a simple soap-free emulsion polymerization in methanol-enriched aqueous medium in a single step process. The size and uniformity of the microspheres are dependent on the polymerization temperature. In a stable system, the uniformity is improved with the polymerization time. The most uniform and stable micro spheres are obtained under mild agitation speed of 100 rpm at 70$^{\circ}C$. The monodisperse PMMA microspheres in the size range of 1.4-2.0 $\mu\textrm{m}$ having less than 5% size variation are successfully achieved with varying concentrations of monomer and initiator. As the monomer and initiator concentrations increase, the larger micro spheres with enhanced uniformity are obtained. However, the decreased amount of water induces the polydisperse PMMA particles due to the generation of secondary particles.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.2
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• pp.165-178
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• 2000

In this study the effects of block distance have been investigated on the particle deposition efficiency in the collecting cell of two-stage electrostatic precipitator by numerical analysis. Particle trajectories have been changed by the electrostatic and inertial force of particle with the inlet velocity electrostatic number and particle diameter. The total deposition efficiency has a minimum value by the interaction between the effect of particle inertial force and electrostatic force in the collecting cell. The increase of block distance makes the total deposition efficiency decrease under the range of the particle size which has the minimum deposition efficiency. However beyond the range of particle size which has minimum deposition efficiency total deposition efficiency has no trend with the variation of block distance.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.47-53
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• 2007

The laminar combustion characteristics of interacting coal particles in a convective flow are numerically investigated at particle arrangement and size difference. The numerical simulations, which use the two-step global reaction model to account for the surrounding gas effect, show the detailed interaction among the inter-space particles, undergoing devolatilization and subsequent char burning. Several parametric studies, which include the effect of the gas temperature (1700 K), high pressure(10 atm) and variation in geometrical arrangement of the particle diameter on the volatile release rate and the char combustion rate, have been carried out. The comparison indicates that the shift to the multiple particle arrangement resulted in the substantial change of the combustion characteristics and that the volatile release rate of the interacting coal particles exhibits a strong dependency on the particle spacing and size difference.

• Journal of Korea Foundry Society
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• v.15 no.4
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• pp.397-407
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• 1995

The objectives of this study are first, to expand our understanding of relationship between magnetic properties and microstructural features such as grain size and texture, and second to reduce core loss of Fe-6.5%Si strip through optimizing heat treatment conditions. A rapid solidification technique, planar flow casting(PFC), was adopted to produce Fe-6.5%Si strips. The strips were heat treated under various conditions. The results show that heat treatment conditions can change not only grain size but also (200) texture formation on the strip surface. Variation in magnetic properties of Fe-6.5%Si strip is analyzed in terms of the change in grain size as well as (200) texture on the strip surface. The heat treatment conditions of $1100^{\circ}C$ over 2 hr or $1150^{\circ}C$ $1{\sim}2hr$ in $N_2+5%H_2$ appear to minimize core loss of Fe-6.5%Si strips.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.166-169
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• 2004

Permalloys were successfully fabricated by melt drag casting in the present study, and their variation of microstructure and consequent magnetic properties were investigated as a function of Si contents and annealing temperature. The increases in Si content and annealing temperature resulted in the increases of grain size and amount of $FeNi_3$ ordered phase. Both the grain size and $FeNi_3$ ordered phase controlled by Si and annealing temperature had a important role on permeability of permalloys.

• Journal of The Korean Astronomical Society
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• v.24 no.1
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• pp.107-116
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• 1991

With a modern microdensitometer and POSS glass copies, we have performed an automated star counting in two colors, blue and red, over the region containing Bok globule B361. Distribution of the measured extinction values over the projected angular distance from the cloud center was approximated by a power-law, and the resulting power-law indices for the blue and red are shown to be distinctly different from each other. The difference in the power-law index indicates that the mean dust size increases towards the cloud center. Possible physical causes for such size variation are briefly discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.611-614
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• 2005

This study concerns the strength of concrete cores drilled from existing structures. The test factors are core size, drilled position of core, concrete age and concrete strength. The test results are as follows; (1) Under the filled condition of curing, concrete strength for three years are larger than that of 28 days by $15\~20\%$ (2) According to the core size effect from diameter of 75mm to 150mm , the variation of core strength are by $8\~18\%$ (3) According to the wall height of 1m, the strength of lower point of wall is than larger that of the upper point by $5\~20\%$. (4) In Accessing the core strength of concrete as a basis, the effect of core size and drilling position should be considered.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.747-750
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• 2003

We have studied PHEMTs optimization by means of fabrication of PHEMTs. All PHEMTs have been fixed with a gate length of 0.1 ${\mu}{\textrm}{m}$, a gate head size of 0.75${\mu}{\textrm}{m}$, and two gate fingers. We have measured the characteristics of PHEMTs with variation of source-drain spacing, pad size, and gate width. As a result, we have found the enhanced characteristics of $I_{dss}$, $S_{21}$, $h_{21}$, $f_{T}$, $f_{max}$, and $G_{ms}$ with increasing gate width. Also, $g_{m}$ has improved with decreasing source-drain spacing, and $S_{21}$ has improved with deceasing pad size.e.e.e.e.