• Journal of the Korean Chemical Society
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• v.59 no.3
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• pp.257-262
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• 2015

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.93-93
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• 2013

To make the rationale design of interface between cell and artificial surface, many studies have been controlled influencing cue which can typically be divided into two central categories: chemical cues based on modification surface chemical properties containing attractive/repulsive molecules, and physical cues that may include applied tension/stress, electrical polarization, magnetic field, and topography. Recently, researches have been focused on physical cue, especially topography. The surface topography may influence cellular responses for example, cell adhesion, cell morphology and gene expression. However, there were few systematic studies about these nanotopographical effects on neuronal developments in a feature size-dependent manner. Herein, we report a nanoscale-resolved study of nanotopographical effects on cellular adhesion and growth. In this study, we use substrates with packed glass beads by rubbing method for generating highly periodic nanotopographies with various sizes. We found that acceleration of neuritogenesis appeared only on the beads larger than 200 nm in diameter, and observed that filopodial thickness was comparable with this scale. This study is expected to be essential to elucidate the nanotopographical effect on cellular adhesion and growth.

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1039-1042
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• 2013

Polyynes were prepared by liquid laser ablation of a graphite target in deionized water at various physical conditions such as laser power (20 and 40 mJ/pulse) and ablation wavelengths (355, 532, and 1064 nm). The effects of physical parameters on the linear carbon chain length were examined by analyzing the densities of polyynes with different carbon numbers ($C_6H_2$, $C_8H_2$, and $C_{10}H_2$) as well as their branching ratios. We concluded the photophysical processes turned out to play a more significant role than thermal ones in the formation of polyynes.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.4
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• pp.160-168
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• 2004

We investigate the effects of solutal convection on the crystal growth rate in a horizontal configuration for diffusive-convection conditions and purely diffusion conditions achievable in a low gravity environment for a nonlinear thermal gradient. It is concluded that the solutally-driven convection due to the disparity in the molecular weights of the component A $(Hg_2Br_2)$ and B (CO) is stronger than thermally-driven convection for both the nonlinear and the linear thermal profiles, corresponding to $Gr_t= 8.5{\times}10^3,\; Gr_s = 1.05{\times}10^5$. For both solutal and thermal convection processes, the growth rates for the linear thermal profile (conducting walls) are greater than for the nonlinear case. With the temperature humps, there are found to be observed in undersaturation for diffusive-convection processes ranging from $D_{AB}$ = 0.087 to 0.87. For the vertical configurations, the diffusion mode is so much dominated that the growth rate and interfacial distribution is nearly regardless of the gravitational accelerations. Also, the diffusion mode is predominant over the convection for the gravity levels less than 0.1 $g_0$ for the horizontally oriented configuration.

• Polymer(Korea)
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• v.38 no.2
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• pp.129-137
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• 2014

In this study, the melt-mixing condition was optimized first to maximize the physical properties of a wood plastic composite (WPC) with recycled polypropylene (PP) and the effects of recycled PP content on the physical properties of the WPC were investigated. Mechanical properties of the WPC were measured by UTM and an izod impact tester and thermal properties were investigated by DSC, TGA and DMA. Fracture surfaces of the WPC were investigated by SEM. The optimized mixing condition of WPC with 50 wt% recycled PP of total PP was melt-mixing at $170^{\circ}C$ for 15 min at 60 rpm. With increasing the content of the recycled PP, the water absorption characteristics of the WPC increased and the thermal and mechanical properties decreased. However, the following was concluded from the analysis of all the physical properties; it was possible adding the recycled PP up to 50 wt% of total PP without a significant decrease in the performance of the WPC.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.39-43
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• 1997

Mercurous chloride (Hg$_2$Cl$_2$) has many advantages in its applications to acousto-optic, and opto-electronic devices because it has the unique properties of a broad transmisson range, well into the far infra-red, a low acoustic velocity, a large birefringence, and a high acousto-optic figure of merit[1]. Hg$_2$Cl$_2$ has a high vapor pressure, hence single crystals are usually grown by physical vapor transport(PVT) method in closed silica glass ampoules. We discuss the application of the laser Doppler velocimetry to measure the flow field inside a closed ampoule. The experimental results, are discussed its relationship to computational model and compared to their expectations.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.78.1-78
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• 2003

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.667-671
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• 1995

The viscometric technique is used to study the effects of microstructure on the viscosity (viscosity vs. concentration or shear rate) of magnetic particle suspensions. In this characterization, measurement of suspension viscosity is used to obtain the dependence of viscous energy dissipation on microstructural state of dispersions. Microstructural shape effects which are related to particle orientation are then indirectly obtained. Empirical formulas from mean field theory and the Mooney equation, which are applicable at high concentration of magnetic particles, are used to relate viscosity to particle concentration. The validity and physical meaning of these equations are discussed.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.83-90
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• 2021

In this study, effects of the physical and chemical properties of low temperature heated carbon on electrochemical behavior as a secondary battery anode material were investigated. A heat treatment at 600 ℃ was performed for coking of petroleum based pitch, and the manufactured coke was heat treated with different heat temperatures at 700~1,500 ℃ to prepare low temperature heated anode materials. The physical and chemical properties of carbon anode materials were studied through nitrogen adsorption and desorption, X-ray diffraction (XRD), Raman spectroscopy, elemental analysis. Also the anode properties of low temperature heated carbon were considered through electrochemical properties such as capacity, initial Coulomb efficiency (ICE), rate capability, and cycle performance. The crystal structure of low temperature (≤ 1500 ℃) heated carbon was improved by increasing the crystal size and true density, while the specific surface area decreased. Electrochemical properties of the anode material were changed with respect to the physical and chemical properties of low temperature heated carbon. The capacity and cycle performance were most affected by H/C atomic ratio. Also, the ICE was influenced by the specific surface area, whereas the rate performance was most affected by true density.

• Applied Chemistry for Engineering
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• v.17 no.2
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• pp.132-137
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• 2006

Polyurethane acrylate hybrid emulsions were prepared by seeded polymerization techniques. In the synthesis, seeded polyurethane dispersion containing a carboxylic group was used to endow hydrophilicity to the hybrid emulsion and various acrylates such as methyl methacrylate (MMA), 2-hydroxy ethylmethacrylate (2-HEMA), n-butyl acrylate (n-BA) and acrylic acid (AAc) were used to endow hydrophobicity. The particle size and distribution of various emulsion particles such as polyurethane acrylate hybrid emulsion, polyurethane dispersion homopolymer, acrylate emulsion, and physical blending emulsion were measured by a particle size analyzer. The average particle size of hybrid emulsion was greater than physical blending emulsion. And tensile strength, 100% modulus, elongation, and swelling properties of the polyurethane acrylate hybrid emulsion were studied and compared with those of polyurethane homopolymer, acrylate emulsion, and physically blended compositor, respectively. To improve chemical and physical resistance, this paper review a melamine hardener and compares it for effects on the physical properties of cured coating.