• Journal of the Korean Applied Science and Technology
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• v.20 no.1
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• pp.8-19
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• 2003

Environmental friendly acrylics/urea high-solid paints (BEHCU) were prepared through the curing reaction of acrylics resin(BEHC) containing 70wt% of solids content and butylated urea curing agent. BEHC was synthesized by addition copolymerization of caprolactone acrylate(CLA), 2-hydroxypropyl methacrylate(2-HPMA), ethyl methacrylate, and n-butyl acrylate. The addition polymerization of these monomers, especially including flexible CLA monomer and 2-HPMA monomer with OH funtional group, under appropriate reaction conditions resulted in polymers with controlled glass transition temperature($T_g$) and crosslinking density. The molecular weight($M_w$) of these polymers(BEHCs) was 2940${\sim}$3240 and polydispersity ($M_w/M_n$) was in the range of 1.61${\sim}$1.72. The viscosity and the molecular weight of these acrylic resins increased with increasing $T_g$. The coated films were prepared using curing reaction between BEHC resin and butylated urea curing agent at 100$^{\circ}C$ for 30 minutes. Our experimental resulted showed that enhancement of the coating properties such as adhesion, flexibility, impact resistance, water resistance, and abrasion resistance could be expected through introducing CLA component in acrylic resin for the high-solid content acrylics/urea coatings.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.2
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• pp.60-69
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• 2004

Application methods of chemicals were investigated to minimize strength reduction of corrugated boards under the high humidity environment encountered in the cold chain system. Starch insolubilizers were introduced in the starch solution preparation of the Stein hall method and their insolubilization effect of starch binder were estimated. The performance of water repellent agents(WRA) and moisture proof agents(MPA) were evaluated in terms of water and moisture resistance. And effects of the combination of the chemicals and the coating method were also examined. Addition of the polyamine polyamide insolubilizer to the main part in the Stein hall process improved the binding force and water resistance of starch, which contributed to minimize the strength reduction of paper under the high humidity environment. AZC and Glyoxal type insolubilizers could not be used in the experiment due to an excessively increased viscosity of starch solution and the poor stability. Conventional WRA treatment to the base paper enhanced water and moisture resistance very slightly even though water repellency of the paper reached R10 by the treatment. MPA showed excellent performance than WRA not only in water and moisture resistance but in water repellency. Double coating on paper with MPA was more effective than the single coating at the same coating weight. A newly developed MPA showed excellent performance and runnability only by a single coating instead of a double coating.

• Polymer(Korea)
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• v.25 no.2
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• pp.240-245
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• 2001

The effect of additives on the orientation of magnetic Sr-ferrite powders has been studied during powder injection molding under applied magnetic field for fabricating multi-pole anisotropic sintered Sr-ferrite magnets. The orientation of the Sr-ferrite powders depends sensitively on the fluidity of powder-binder mixture, related to the binder additives and the injection molding temperature, and the magnetic field intensity. The orientation of Sr-ferrite powders is good for the compacts with stearic acid added in the binder system of paraffin wax/carnauba wax/HDPE, but it is poor for the compacts with silane coupling agent added. The orientation of Sr-ferrites higher than 80% is achieved at the following useful conditions; apparent viscosity lower than 2500 poise in 1000 sec$^{-1}$ shear rate and applied magnetic field higher than 4 kOe.

• Elastomers and Composites
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• v.35 no.2
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• pp.106-114
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• 2000

The foam of ethylene vinyl acetate (EVA)/styrene-vinyl isoprene-styrene triblock copolymer(SVIS) blend was prepared to improve the shock-absorption and compression set characteristics at room temperature. The effects of blowing agent and blend ratio of EVA/SVIS on expansion ratio, cell structure and mechanical properties of the foam were investigated. As the SVIS content increased, the viscosity of blends was increased but the crosslinking rate was slow down, the expansion ratio was decreased. and the specific gravity was increased. At room temperature, the resilience was not affected by increasing the amount of blowing agent. The value of tan ${\delta}$ was increased by increasing the amount of SVIS. As a result, the value of compression set was decreased. This is due to the increased values of specific gravity and crosslinking density of the EVA/SVIS foam.

• Elastomers and Composites
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• v.48 no.2
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• pp.114-124
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• 2013

To study the effects of structural difference and fatty acid chain length of glyceride, new dispersion agents having various glyceride structures such as mono-, di-, and tri-, were prepared using glycerol extracted from palm oil and fatty acid having various chain length ranges from 12 to 18. These dispersion agents were mixed with the rubber compounds and compared with conventional metal salt dispersion agents. Glyceride dispersion agent provided remarkable improvement in silica dispersion, compared to metal salt fatty acidic one, even though the viscosity of mixtures was relatively high due to low lubricating effect, and this was approved by mechanical properties, wear properties, and Payne effect. Also, the longer in chain length of fatty acid and the smaller in numbers of fatty acid, the dispersity of silica was improved.

• Elastomers and Composites
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• v.37 no.1
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• pp.31-38
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• 2002

Polymerization of carboxylated styrene-butadiene latex takes longer time than that of acrylic emulsion due to delocalization of radical in butadiene unit having conjugated double bond. A latex stability is the most important properties owing to use intact without separating polymer from base latex. For reducing polymerization time without decreasing any properties of latex, carbon tetra-chloride which has been used as the most popular chain transfer agent was replaced to combination of tert-dodecylmercaptane and ${\alpha}$-methylstyrene dimer. The replacement yielded reducement or 2 hr in polymerization time. In the increment step, charge amount of acrylic acid was limited to 0.3 part to restrain viscosity enhancement. Just after initial step, addition of 0.1 part acrylamide prevent polymer chain from diffusing between two region followed by giving hardness and final good adhesive force to latex particles.

• Journal of dental hygiene science
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• v.10 no.2
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• pp.79-83
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• 2010

This study manufactured hydrogel, which was contained NSAIDs(non-steroidal anti-inflammatory drugs) Ketorolac tromethamine and hydrolyzed products of gardeniae fructus extract, and experimented viscosity, surface tension, tensile strength and bio-adhesiveness by using hairless mouse. Thus, it was performed in expectation for being probably able to develop as effective auxiliary agent of periodontal disease after non-surgical or surgical periodontal treatment. As a result, the following conclusions were obtained. 1. Out of KGE and KGH gel materials, the content of ketorolac tromethamine was 1.02~0.97%. The content of geniposide was 0.34% in KGE gel A and C. However, it got lower to 0.11% in KGH gel B and D. The content of genipin wasn't shown in KGE gel A and C, but was shown with 0.13% in KGH gel B and D. 2. As for viscosity according to temperature in gel material, the gel, which used independently Carbopol 940 as gel inoculant, maintained the higher viscosity than the gel, which added Poloxamer 407. The surface tension in each material showed 34.77~40.58 dyne/cm at 37. As for tensile strength in material, KGH gel B was shown the higher tensile strength in about 3.5 times compared to the control group. 3. As for bio-adhesiveness, the back-skin upper part(epidermis) and abdomen skin were shown to be 50.62 N in KGH gel B, thereby having indicated higher value in about 5 times compared to control group. The back-skin lower part(dermis) and abdomen skin were shown to be 35.93 N in KGH gel B, thereby having indicated higher value in about 3.5 times compared to control group.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.657-665
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• 2013

The purpose of this study is the basic research of self-compacting concrete using Alkali-Activated Slag (AAS) binder in order to emphasize the durability of structures and facilitate casting the fresh concrete in field. The AAS binder emitted low carbon dioxide ($CO_2$) is eco friendly material of new concept because AAS products not only emit little $CO_2$ during production but also reuse the industrial by-products such as ground granulated blast-furnace slag (GGBS) of the steel mill. Until now, almost of domestic and foreign research are using Ordinary Portland Cement (OPC) for self-compacting concrete, and also, nonexistent research about AAS. The self-compacting concrete must get the performance of flowability, segregation resistance, filling and passing ability. Nine concrete mixes were prepared with the main parameter of unit amount of binder (400, 500, 600 $kg/m^3$) and 3 types of water-binder (W/B) ratio. The results of test were that fresh concretes were satisfied with flowability, segregation resistance, and filling ability of JSCE. But the passing ability was not meet the criteria of EFNARC because of higher viscosity of AAS paste than OPC. This high viscosity of AAS paste enables the manufacturing of self compacting concrete, segregation of which does not occur without the using of viscosity agent. It is necessary that the development of high fluidity AAS binders of higher strength and the study of better passing ability of AAS concrete mixes in order to use self compacting AAS concrete in field.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.698-705
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• 1994

The basic medium oil modified alkyd resin was synthesized from linseed oil fatty acid(LOFA), phthalic anhydride(PAA), maleic anhydride(MA) and trimethylol propane(TMP) by condensation polymerization at $230^{\circ}C$. MA/TMPTA modified water-reducible alkyd resins were synthesized with TMPTA graft copolymerization onto the basic resin at $180^{\circ}C$. Acid value of the resin was controlled by the addition amount of MA and N,N-dimethylethanol amine(DMEA) was used as a neutralizing agent to prepare of the water-reducible alkyd resin. The effect of TMPTA on the graft copolymerization of the resin was studied by measuring molecular weight glass transition temperature(Tg), viscosity, graft efficiency, and gel contents of melanin cured film. Heat resistance, UV resistance and water resistance of cured film of MA/TMPTA modified resin was compared to those of TMA/TMPTA modified alkyd resin. The molecular weight, viscosity gel contents and graft efficiency of water reducible alkyd resin were increased according to the TMPTA graft copolymerization, but Tg was decreased. The viscosity was lower when the solid contents reached 40% than that of 30% content and also and also became lower with the extent of neutralization ratio, The heat resistance, UV resistance and water resistance of the MA/TMPTA modified alkyd resis were better than those of TMA/TMPTA modified alkyd resin but the storage stability of the TMA/TMPTA alkyd resis was better than that of MA/TMPTA modified alkyd resin.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.787-798
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• 2017

This is a study on characteristics according to the material of sheet-type mask packs being sold on the market. The absorption capacities of water soluble components such as purified water, 1.3-propanediol, 1.3-butylene glycol, glycerine, and hyaluronic acid are compared with that of various oils including cyclomethicone, dimethicone, phytosqualane, caprylic capryl triglyceride, grape seed oil, and macadamia nut oil. As a result, all of the water soluble components except purified water showed higher moisture absorption capacity as the viscosity increased. And in case of oil, all oil showed higher oil absorption capacity according to the viscosity. During this test, the mask sheets with the type of acetic acid fermented bio-cellulose showed 500~1,000 times or more absorption capacity on water soluble wetting agent or all oils, which is due to the fine mesh structure seen in the 5,000x enlarged photograph at surface structure. This mesh structure was well recognized on the cross section and these structural features enhance the absorption capacity of water and oil. It is also believed that largely contained water-soluble components and oils facilitate the discharge over time. In addition, since each mask sheet shows their characteristics according to their material, it is intended to be a basic research for manufacturing mask packs good for skin.