• Journal of Pharmaceutical Investigation
• /
• v.19 no.2
• /
• pp.99-107
• /
• 1989

In order to develop a pediatric liquid preparation with sustained release properties, dextromethorphan hydrobromide (DEXT) was complexed with strong cation exchange resin (CG 120) and the-complex was coated with Eudragit RS using a phase separation method by non-solvent addition. The effect of pH, ionic strength of the release medium and drug/resin ratio on the release rate of DEXT was studied. The release rate of free drug from the uncoated complex, and coated complexes with 9.5 and 18.5% Eudragit RS in artificial gastric juice were measured. The release rate from the uncoated complex was faster with higher pH, higher ionic strength of the release medium and higher drug/resin ratio. The release rate from the coated complex could be controlled by the amount of coating material, and the surface after release did not rupture into.

• Applied Microscopy
• /
• v.47 no.1
• /
• pp.55-62
• /
• 2017

This paper describes experiments aimed at characterizing the behavior of field electron emitters fabricated by coating carbon fibers with epoxylite resin. Polyacrylonitrile carbon fibers of type VPR-19, thermally treated at $2,800^{\circ}C$, were used. Each was initially prepared in a "uncoated" state, by standard electro polishing and cleaning techniques, and was then examined in a scanning electron microscope. The fiber was then baked overnight in a field electron microscope (FEM) vacuum chamber. Current-voltage characteristics and FEM images were recorded on the following day or later. The fiber was then removed from the FEM, coated with resin, "cured" by baking, and replaced in the FEM. After another overnight bake, the FEM characterization measurements were repeated. The coated fibers had significantly better performance than uncoated fibers. This confirms the results of earlier experiments, and is thought to be due in part to the formation of a conducting channel in the resin over layer. For the coated fiber, lower voltages were needed to obtain the same emission current. The coated fibers have current-voltage characteristics that show smoother trends, with greater stability and repeatability. No switch-on phenomena were observed. In addition, the emission images on the phosphor-coated FEM screen were more concentrated, and hence brighter.

• Polymer(Korea)
• /
• v.36 no.3
• /
• pp.268-274
• /
• 2012

The silane coupling agent, 3-(trimethoxysilyl)propyl methacrylate (${\gamma}$-MPTS), was grafted on the surface of alumina nanoparticles. We used the surface modified nanoparticles in the hard coating layer for in-mold decoration (IMD) foils and evaluated the coating properties such as hardness and anti-abrasion property. The effects of electron beam (EB) irradiation on color layer and anchor layer of IMD foils were observed through the difference in color and the cross-cut tape test, respectively. Also, cure kinetics as studied quantitatively under various reaction temperatures by analysis of surface properties and Fourier transform infrared (FTIR) spectroscopy. From these results, we constructed database for the commercial exploitation of EB curing system.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.9
• /
• pp.1491-1497
• /
• 1997

The purpose of this research is to improve the surface roughness of cast-iron pipe porduced by the centrifugal casting. A twin-fluid atomizer of mold-wash slurry is designed for this project. New atomizer is equipped with the existing manufacturing facility to produce pipes. Cast-iron pipes (.cent.125*L3000mm) are produced and the surface roughnesses of those are analysed by UBM. The average surface roughness of new products is 6.7.mu.m while the old products of sand-resin coating method have 17.0.mu.m of average surface roughness. The surface roughness of cast-iron pipe is improved very much than before.

• Fire Science and Engineering
• /
• v.29 no.1
• /
• pp.12-18
• /
• 2015

This study has conducted an experiment of comparing the flame resistant performance and combustion characteristics according to flame resistant treatment using the Cypress Luba and particle board that is commonly used for interior decoration and furniture. As a result of testing the flame resistant performance of Cypress Luba, the Cypress Luba injected with flame resistant resin using the vacuum pressure treatment has shown to have better performances (carbonized area 9.55% and carbonized length 22.91%) than the Cypress Luba treated with flame resistant coating having rubberized plastic components on its surface. For particle board, the specimen attached with fireproof film was identified to be better (carbonized area 40.10% and carbonized length 43.40%) than the specimen with non-fireproof film. For the results of combustion characteristics using the Cone Calorimeter, the specimen treated with flame resistant coating on the surface had faster ignition than the Cypress Luba injected with fire resistant resin using vacuum pressure treatment, and in the total release of calories, the Cypress Luba injected with fire resistant resin using vacuum pressure had $68.2MJ/m^2$, and the specimen treated with fire resistant coating on the surface had $111.52MJ/m^2$. For the particle board, the ignition time had a little difference but in the total release of calories, the specimen attached with fireproof film had $90.1MJ/m^2$ and the specimen with non-fireproof film had $107.6MJ/m^2$.

• Applied Chemistry for Engineering
• /
• v.1 no.1
• /
• pp.63-72
• /
• 1990

Surface of crystalline silica was sequentially reacted with silane(A 187), liquid rubber(CTBNx8) and vinyl monomer(AA, MMA, 2-HEA, GMA) in existance of amines(TEA, CTMAB, BETAC) or peroxide(BPO). By mixing it with epoxy resin at a ratio 0~36%(volume %) of total component, liquid properties of mixtures was investigated experimentally. i) Coating ratio depended on quantity and sorts of catalyst. ii) Total coating of 2.5~5.8% was attained by using 0.1~2.0% of catalyst. iii) Treated surfaces represented each different features in according to sorts of treatment. iv) Silane/rubber or silane/rubber/vinyl represented lower viscosity and settling than non-treated or silane-treated.

• Composites Research
• /
• v.34 no.3
• /
• pp.148-154
• /
• 2021

Carbon/epoxy composite bipolar plate (BP) is a BP that is likely to replace existing graphite bipolar plate of vanadium redox flow cell (VRFB) due to its high mechanical properties and productivity. Multi-functional carbon/epoxy composite BP requires graphite coating or additional surface treatment to reduce interfacial contact resistance (ICR). However, the expanded graphite coating has the disadvantage of having low durability under VRFB operating conditions, and the surface treatments incur additional costs. In this work, an excessive resin absorption method is developed, which uniformly removes the resin rich area on the surface of the BP to expose carbon fibers by applying polyester fabric. This method not only reduces ICR by exposing carbon fibers to BP surfaces, but also forms a unique ditch pattern that can effectively hold carbon felt electrodes in place. The acidic environmental durability, mechanical properties, and gas permeability of the developed carbon/epoxy composite BP are experimentally verified.

• Journal of the Korean Ceramic Society
• /
• v.42 no.10 s.281
• /
• pp.645-648
• /
• 2005

To fabricate a (100) silicon hard master, we used anisotropic wet etching for the embossing. The etching chemical for the sili­con wafer was a TMAH 25$\%$ solution. The anisotropic wet etching produces a smooth sidewall surface inclined at 54.7°, and the surface roughness of the fabricated master is about 1 nm. After spin coating an organic-inorganic sol-gel hybrid resin on a silicon substrate, we used the fabricated master to form patterns on the silicon substrate. Thus, we successfully obtained patterns via the hot embossing technique with the (100) silicon hard master. Moreover, by using a single hydrophobic surface treatment of the master, we succeeded in achieving uniform surface roughness of the embossed patterns for more than ten embossments.

• Corrosion Science and Technology
• /
• v.12 no.1
• /
• pp.1-6
• /
• 2013

Recently Digital TV industry has drastically been moving the illuminating system, which causes an obvious product change from PDP and LCD to LED model to provide high-definition image. Due to strong competition in the digital industry, TV manufacturers make a great efforts to reduce production cost by using low-priced materials such as steels instead of aluminum and plastic etc. In this paper we have developed a new low-priced electrogalvanized steel sheet, which has a black resin composite layer, to substitute conventional high-priced PCM steel and plastic mold for rear cover panel in the digital TV. The black resin composite was prepared by mechanical dispersion of the mixture solution that consists of high solid polyester resin, melamine hardener, black pigment, micronized silica paste, polyacrylate texturing particle and miscellaneous additives. The composite solution was coated on the steel sheet using roll coater followed by induction furnace curing and cooling. Although the coated layer has a half thickness compared to the conventional PCM steels having $23{\mu}m$ thickness, it exhibits excellent quality for the usage of rear cover panel. The new steel sheet was applied to test products to get quality certification from worldwide electronic appliance customers. Detailed discussion provides in this paper including preparation of composite solution, roll coating technology, induction curing technology and quality evaluation from customers.

• Journal of the Korean Electrochemical Society
• /
• v.1 no.1
• /
• pp.55-59
• /
• 1998

The water absorption in protective coatings, which may greatly influence the durability of these coatings, was studied using quartz crystal microbalance and electrochemical impedance technique. The water absorption in protective coatings and the change of coating capacitance with concentration of electrolyte were measured. The water absorption in coatings seems to be driven by osmotic pressure, and larger amount of water was absorbed in thinner coatings at initial stage of absorption. The amount of water absorbed in coatings changed with the type and crosslinking density of resin used in coating formulation. When water absorption and desorption of coating occured by exposing the coatings to electrolyte solutions of different concentration, increase in impedance caused by desorption of water was found to be higher in the case of thinner film.