• Polymer(Korea)
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• v.24 no.4
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• pp.520-528
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• 2000

New high solid acrylic resins (BMHA) containing 70% of solids content have been synthesized. The environmental friendly high solid coatings (BNHS) were prepared by using these acrylic resins and polyisocyanates. The BMHA was obtained by introducing a new functional group, acetoacetoxyethyl methacrylate (AAEM), in the copolymerization of n-butyl acrylate, methyl methacrylate, and 2-hydroxyethyl acrylate. Lowering T$_{g}$ and increasing the AAEM amount in the BMHA resulted in a high value of conversion. There was no difference in conversion with the variations of OH values. In the next step, high solid BNHS coatings were prepared by the curing reaction between BMHA and polyisocyanate at room temperature. The properties of these coatings were evaluated especially for the application of automotive top-coating materials. The introduction of AAEM in the BNHS enhanced the abrasion resistance and solvent resistance of the coatings, which indicated the possible use of BNHS coatings for top-coating materials of automobile..

• Journal of Environmental Science International
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• v.17 no.11
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• pp.1227-1233
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• 2008

The effect of freeze drying and fixatives in post-treating freeze drying on the morphological properties of the rose (Rosa hybrida L.) petal were investigated for the production of high quality of freeze dried rose. The morphology including form and color of the dried flowers of cut rose were depended on the drying methods. The drying time was extended due to their density and water content, and was shorter in the freeze drying than that in the natural and hot air drying. Freeze dried process for dried flowers took 2 days in a freeze dryer and did not cause shrinkage or toughening of rose petal being dried, preserving its natural shape and color. The diameter of freeze dried flowers showed little reduction compared to fresh flowers. In Hunter color values of petals of freeze dried flowers, L and a values were high and showed little variations in comparison to fresh petals. Freeze drying led to a noticeable increase in anthocyanin contents in petals, suggesting that anthocyanin contents play an important role in the acquisition of freezing tolerance. Exposure of flowers to freeze drying was accompanied by an increase in the carotenoid content. In the post-treating freeze drying, epoxy resin, a fixative, applied alone or in combination to petals of freeze dried flowers showed efficient coating for the protection from humidity and sunlight. Combined application of epoxy and acetone to freeze dried petals permitted maintenance of natural color and excellent tissue morphology, showing color stability and shiny texture in surface of petals. These findings suggest that application of fixatives to freeze dried rose petals improves the floral preservation and epoxy coating provides good quality in the freeze dried flower product.

• Journal of Powder Materials
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• v.21 no.5
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• pp.360-365
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• 2014

$SnO_2-CoO$/carbon-coated CoO core/shell nanowire composites were synthesized by using electrospinning and hydrothermal methods. In order to obtain $SnO_2-CoO$/carbon-coated CoO core/shell nanowire composites, $SnO_2-Co_3O_4$ nanowire composites and $SnO_2-Co_3O_4$/polygonal $Co_3O_4$ core/shell nanowire composites are also synthesized. To demonstrate their structural, chemical bonding, and morphological properties, field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were carried out. These results indicated that the morphologies and structures of the samples were changed from $SnO_2-Co_3O_4$ nanowires having cylindrical structures to $SnO_2-Co_3O_4/Co_3O_4$ core/shell nanowires having polygonal structures after a hydrothermal process. At last, $SnO_2-CoO$/carbon-coated CoO core/shell nanowire composites having irregular and high surface area are formed after carbon coating using a polypyrrole (PPy). Also, there occur phases transformation of cobalt phases from $Co_3O_4$ to CoO during carbon coating using a PPy under a argon atmosphere.

• Journal of Adhesion and Interface
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• v.21 no.2
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• pp.58-64
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• 2020

This paper describes a simple approach for preparing a superhydrophobic and superoleophobic coating via spraying the mixture of UV-curable polyurethane acrylate and silica nanoparticles dispersed in a solvent. The prepared surface structures can be controlled by changing the types of solvents, the concentration of the polymer, and the amount of spraying. Superhydrophobicity and superoleophobicity are quantified by measuring the contact angle of water and oil, respectively. We also demonstrate the mechanism of spray coating with maximized superhydrophobicity and superoleophobicity through the analysis of re-entrant surface structures. At the appropriate amount and the composition of mixed solutions, the contact angle hysteresis of water and oil on the prepared surface is less than 2° and 30°, respectively. In addition, it shows excellent water-repellent and oil-repellent properties such that the oil droplet bounces off the surface.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.4
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• pp.208-213
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• 2009

Artificial lightweight aggregates were produced by using bottom ashes and dredged soils from coal power plant. The amount of glassy phases on the aggregate surfaces, specific gravities, absorption rates, and observations of cross-sectional surfaces were compared according to the compositions, sintering temperatures, and the amount of coating. It is concluded that surface modification by 10 % $CaCO_3$ coating on the aggregate surfaces enhances the properties of aggregates as follows: Specific gravities were controlled by depressing formation of large pores in the aggregates. Sticking phenomena among aggregates during the sintering process was drastically decreased by reducing glassy phases on the aggregate surfaces. Pumping problems during the application of ready-mix concretes containing lightweight aggregates having high value of absorption rates could be solved by reducing the absorption rate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1092-1098
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• 2006

The influence of the concentration of precursor solution and the number of solution coatings on the densification of the $Pb(Zr_xTi_{1-x})O_3$ (PZT) thick films was studied. PZT powder and PZT precursor solution were prepared by3 sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The composition of powder and precursor solution were PZT(70/30) and PZT(30/70), respectively. The PZT precursor solution was spin-coated on the PZT thick films. A concentration of a coating solution was 0.5 to 2.0 mol/L[M] and the number of coating was repeated from 0 to 6. The XRD patterns of all PZT thick films shelved typical perovskite polycrystalline structure. The porosity of the thick films was decreased with increasing the number of coatings and 6-time coated films with 1.5 M showed the dense microstructure and thickness of about $60{\mu}m$. The relative dielectric constant of the PZT thick film was increased with increasing the number of solution coatings and the thick films with 1.5 M, 6-time coated showed the 698. The remanent polarization the 1.5 M and 6-time coated PZT thick films was $38.3{\mu}C/cm^2$.

• Journal of the Korean Institute of Gas
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• v.6 no.4 s.18
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• pp.40-46
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• 2002

This study has been carried out to evaluate the reliability by examining the properties related to durability of commercially available coating systems in domestic. For this purpose slow crack growth resistance and oxidative induction time tests were introduced, which have been accepted as durability parameters in polyethylene pipes with low pressure. Based upon the experimental results on these parameters, desirable minimum values are proposed for the durability enhancement of the polyethylene coatings.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.1
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• pp.7-11
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• 2006

Since ceramic layers coated on machinery components inevitably experience the changes in their properties it is necessary to evaluate the characteristics of ceramic coating layers nondestructively for a reliable use of coated components and 4heir remaining life prediction. To address such a need, in the present study, an ultrasonic backward radiation technique is applied to investigate the characteristics of leaky Rayleigh surface waves propagating through the very thin TiN ceramic layers coated on AISI 1045 steel or austenitic 304 steel substrate with three different conditions of surface roughness, coating layer thickness and wear condition. In the experiments performed in the present work, the peak angle and the peak amplitude of ultrasonic backward radiation profile varied sensitively according to three specimen preparation renditions. in fact, this result demonstrates a high possibility of the ultrasonic backward radiation as an effective tool for the nondestructive characterization of the resting layers even in such a thin regime.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.748-758
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• 2014

The purpose of this study is to find the optimum conditions for manufacturing titanium dioxide using a hybrid self-assembly forming method, to confirm the shape, properties and synergy effect of UV protection for hybrid titanium dioxide. Hybrid titanium dioxide, manufactured by forming self-assembly of different sizes consisting of two kinds of titanium dioxides, has micro titanium dioxide (250nm~300nm) for support material, Nano titanium dioxide (20~30nm) for surface material, coating support material. Adjustment experiments of $AlCl_3$ concentration and both titanium dioxide ratio were conducted to find the optimized conditions for the surface coating of titanium dioxide striking a negative charge, a sample made of the optimized process was confirmed through an optical analysis, particle size analysis, and potentiometric analysis. The SPF in-vitro value of the cosmetics samples containing hybrid titanium dioxide showed 15~30% higher levels than the cosmetics samples containing both titanium dioxides mixture.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.117-122
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• 2010

Recently, aspheric glass lens molding core is fabricated with tungsten carbide(WC). If molding core is fabricated with silicon carbide(SiC), SiC coating process, which must be carried out before the Diamond-Like Carbon(DLC) coating can be eliminated and thus, manufacturing time and cost can be reduced. Diamond Like Carbon(DLC) is being researched in various fields because of its high hardness, high elasticity, high durability, and chemical stability and is used extensively in several industrial fields. Especially, the DLC coating of the molding core surface used in the fabrication of a glass lens is an important technical field, which affects the improvement of the demolding performance between the lens and molding core during the molding process and the molding core lifetime. Because SiC is a material of high hardness and high brittleness, it can crack or chip during grinding. It is, however, widely used in many fields because of its superior mechanical properties. In this paper, the grinding condition for silicon carbide(SiC) was developed under the grinding condition of tungsten carbide. A silicon carbide molding core was fabricated under this grinding condition. The measurement results of the SiC molding core were as follows: PV of 0.155 ${\mu}m$(apheric surface) and 0.094 ${\mu}m$(plane surface), Ra of 5.3 nm(aspheric surface) and 5.5 nm(plane surface).