• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.91-94
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• 2006

In this paper, in order to get micro or nano size optical patterns, an analytical and experimental investigation on a LGP (light guide plate) injection molding process has performed. The LGP, which diffusing and emitting the light from the CCFL or the LEDs to the panel front direction uniformly, typically has an under 1mm thick base substrate and numerous 60 to $170{\mu}m$ width and 6 to $10{\mu}m$ thick dot patterns on it. Generally, the small size LGPs, for mobile devices, have been and are being made of PMMA through the injection molding process. However, the substrate thickness and the dot pattern size are decreasing, it becomes hard to fill the micro to sub-micro cavities completely. To investigate the flow behavior of resin in micro/nano cavities and identify the characteristics of the LGP injection molding process, we carried out the flow analyses with respect to the variations of the substrate thickness, the dot pattern size and the pitch of a cavity.

• Journal of Powder Materials
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• v.17 no.2
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• pp.123-129
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• 2010

The fabrication of interconnect from titanium powders and $TiN_x$ powders is investigated. Corrosion-resistant titanium and $TiN_x$ are used as reinforcement in order to reveal high heat and corrosion resistance at the elevated temperature. We fabricated the plates for interconnect reinforced with $TiN_x$ by mixing titanium powders with 10 wt.% of nano-sized $TiN_x$. Spark Plasma Sintering (SPS) was chosen for the sintering of these composites. The plate made of titanium powders and $TiN_x$ powders demonstrates higher corrosion resistance than that of the plate of titanium powders alone. The physical properties of specimens were analyzed by performing hardness test and biaxial strength test. The electrochemical properties, such as corrosion resistance and hydrogen permeability at high temperature, were also investigated. The microstructures of the specimens were investigated by FESEM and profiles of chemical compositions were analyzed by EDX.

• Current Photovoltaic Research
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• v.5 no.3
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• pp.83-88
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• 2017

The growth of intermetallic compounds is an important factor in the reliability of solar cells. Especially, the temperature change in the soldering process greatly affects the thickness of the intermetallic compound layer. In this study, we investigated the intermetallic compound growth by Sn-diffusion in solder joints of solar cells. The thickness of the intermetallic compound layer was analyzed by IR lamp power and hot plate temperature control, and the correlation between the intermetallic compound layer and the adhesive strength was confirmed by a $90^{\circ}$ peel test. In order to investigate the growth of the intermetallic compound layer during isothermal aging, the growth of the intermetallic compound layer was analyzed at $85^{\circ}C$ and 85% for 500 h. In addition, the activation energy of Sn was calculated. The diffusion coefficient of the intermetallic compound layer was simulated and compared with experimental results to predict the long-term reliability.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.429-434
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• 2012

Ignition delay of micro/nano aluminum particles is caused by aluminum oxide shell. The method of minimizing this ignition delay is proposed in the study. Generating and heating of particles are processed at the same time. As soon as heated particles are produced, they immediately contact with oxygen. Chemical reaction is induced on the contact surface instead of crystallization of oxide shell. Finally particles are ignited. Aluminum particles are generated by laser ablation on an aluminum plate using Nd:YAG pulse laser. Injected particles are confirmed through visualization of particles using scattering method. $CO_2$ continuous laser supplies heat to aluminum plate and generated particles. Trace of burning particles is observed in the experiment.

• Computers and Concrete
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• v.19 no.6
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• pp.677-687
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• 2017

The nonlinear buckling response of nano composite anti-symmetric functionally graded polymeric microplate reinforced by single-walled carbon nanotubes (SWCNTs) rested on orthotropic elastomeric foundation with temperature dependent properties is investigated. For the carbon-nanotube reinforced composite (CNTRC) microplate, a uniform distribution (UD) and four types of functionally graded (FG) distribution are considered. Based on orthotropic Mindlin plate theory, von Karman geometric nonlinearity and Hamilton's principle, the governing equations are derived. Generalized differential quadrature method (GDQM) is employed to calculate the non-linear buckling response of the plate. Effects of FG distribution type, elastomeric foundation, aspect ratio (thickness to width ratio), boundary condition, orientation of foundation orthotropy and temperature are considered. The results are validated. It is found that the critical buckling load without elastic medium is significantly lower than considering Winkler and Pasternak medium.

• Journal of the Korean Applied Science and Technology
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• v.26 no.3
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• pp.335-340
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• 2009

This study investigates the paste mixing of positive active materials which, affect the life cycle of batteries in Pb-Ca-Sn grids, and generation of 4BS in a curing process and considers the effects of these things on the initial charge characteristics and life cycle. In the results of the experiments applied in this study, it was possible to reduce the curing time in which the fine 4BS was formed by the mixing of the positive active materials of lead acid battery applied at high temperature compared to that of the existing coarse 4BS and that represented some improvements in the life cycle performance.

• Journal of the Korean Applied Science and Technology
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• v.25 no.4
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• pp.518-524
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• 2008

In this study, positive plates of lead acid battery of Pb-Ca alloy and Pb-Ca-Sn alloy were fabricated and the mechanical characteristics of positive plates were measured. This study observed how the changes of content of Ca & Sn affect interface corrosion which is located in between grid & active materials and lead acid batteries as well. The mechanical characteristics of grid alloy is better when Ca is 0.05 wt.% then 0.1 wt.%. This study said that the corrosion rate between the active material based on the charge/discharge cycle of lead acid battery and grid interface is much faster than a grid which contains Sn. And furthermore, according to the study the rate 30 of Sn/Ca which is added to grid shows the best performance.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.277-280
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• 2008

Recently, a demand of nano/micro patterned polymer for display or biochip has been rising. Then many studies have been carried out. Nano/micro-embossing is a deformation process where the workpiece materials is heated to permit easier material flow and then forced over a planar patterned tool. In this work, the hot-emboss process is performed with different forming conditions; forming temperature, load, press hold time, to get the proper condition for linear pattern fabrication on plated-type polymers (PC). Replicated pattern depth increases in proportion to the forming temperature, load and time. Reduction of the workpiece thickness increases according to press hold time. In process of time, reduction ratio of workpiece thickness decreases because of surface area increment of the workpiece and pressure decline on it.

• Advances in nano research
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• v.7 no.1
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• pp.51-61
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• 2019

This paper develops a four-unknown refined plate theory and the Galerkin method to investigate the size-dependent stability behavior of functionally graded material (FGM) under the thermal environment and the FGM having temperature-dependent material properties. In the current study two scale coefficients are considered to examine buckling behavior much accurately. Reuss micromechanical scheme is utilized to estimate the material properties of inhomogeneous nano-size plates. Governing differential equations, classical and non-classical boundary conditions are obtained by utilizing Hamiltonian principles. The results showed the high importance of considering temperature-dependent material properties for buckling analysis. Different influencing parametric on the buckling is studied which may help in design guidelines of such complex structures.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.5
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• pp.218-223
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• 2013

In this study, the reflectivity characteristics of Ag nano-coating grown by electroless plating were investigated in order to use as the reflecting plate of BLU (Back Light Unit) in the LCD (Liquid Crystal Display) or LED (Light Emitting Diode) display equipment. The microstructure of Ag nano-coating was polycrystalline nano-structure that consisted of Ag nano-crystals to be reduced and precipitated, and the size of reduced nano-crystals increased as the thickness of nano-coating increased. The reflectivity of Ag nano-coating in the visible light decreased as the thickness of nano-coating increased and the reduction of reflectivity was more severe in the short wavelength region of visible light. The decrease of reflectivity was closely related to the size of Ag nano-crystal and was thought to be due to the larger surface roughness of larger nano-coating thickness. Therefore, the finer Ag nano-crystals and thinner nano-coating thickness could be favorable for the higher reflectivity of Ag nano-coating grown by electroless plating.