• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.388-396
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• 2008

2 Components polyurethane coatings are widely used for the industrial coating in general because of its excellent film performance and the workability which were brought by the 3 dimensional cross linked chain structures being formed after the reaction between polyol and polyisocyanate. 2 components polyurethane can be classified into alkyd polyol, polyester polyol, acrylic polyol and polyester modified acrylic polyol depending on where it is used. This research was conducted under the conditions below; different chemical compositions of resin for paint, set the same conditions of viscosity, thinner and acid value, set alternative polyols, OH values and catalysts, set alternative polyisocyanate hardeners of the paint, measure the reaction rates and dynamic mechanical characteristics using RPT-3000, Rotation Rheometer, DMA and FTIR. The research found that the reactivity between polyol and isocyanate influences the film performance and workability depending on the catalysts, OH values and chemical compositions. We find out that different reaction rate of acrylic polyol and polyester modified acrylic polyol with poly-isocyanate is not influenced on temperature and catalyst. In addition, reaction speed of high hydroxyl content polyol is faster than low hydroxyl equivalent. These results can improve difficult working condition to apply urethane coating.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1741-1746
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• 2010

This study is on development of UV-cured anti-stain coating compounds which have more improved anti-stain function to prevent a surface of PVC tile from stain. To make an anti-stain coating composition, water soluble antistatic agent made from ammonium(IV) salt, antistatic agents for acrylic and polyurethane were used. Their contents varied from 5 to 20wt% against quantities of resin in coating composition. After coating PVC tiles using bar-coating method that can adjust a thickness, we estimated surface properties of coated layer such as anti-stain, electric resistance, adhesive power, thickness of coating, and so on. Results showed that a coating composition added 15wt% of water soluble antistatic agent and coated with No.12 bar-coater had the optimum surface property in electric resistance($3.24{\times}10^9{\Omega}/cm^2$), anti-stain(ink Test, Dust Test) and adhesive power. We could also find electric resistance and anti-stain effect were improved as antistatic agent content increased. However, excessive addition of antistatic agents(over 20wt%) caused the migration.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.46 no.2
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• pp.159-166
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• 2020

Propolis is a sticky resinous substance that is formed by the combination of honeybee secretions and resin of plants, which serves to protect from bacteria and viruses. This study aims to evaluate the efficacy of propolis extract from Korea (KPE), China (CPE), and Brazil (BPE) through antioxidant, antibacterial, whitening, and anti-inflammatory tests, and to examine their potential as cosmetic materials. KPE, CPE, and BPE showed significant antioxidant activities on flavonoid/polyphenol content and free radical scavenging activity. The antibacterial effect of propolis on skin flora was determined by measuring the minimal inhibitory concentration (MIC). KPE showed better antibacterial efficacy than CPE and BPE in C. acnes (KPE, CPE, and BPE: (62.5, 250, and 500) ㎍/mL, respectively). Furthermore, KPE inhibited the melanin synthesis in human epidermal melanocytes and production of nitric oxide and PGE₂ induced by lipopolysaccharide (LPS) in mouse macrophages, which showed better than did CPE or BPE. Taken together, the propolis extracts can be applied to antioxidant, antibacterial, and anti-inflammatory ingredient for cosmetics, while KPE showed superior potential in antibacterial, anti-inflammatory, and whitening efficacies.

• Journal of the Korean Wood Science and Technology
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• v.37 no.4
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• pp.388-396
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• 2009

In our study, the potential of okara as an ingredient of new bio-based adhesives was investigated for the production of fancy-veneered flooring boards. Okara was hydrolyzed by 1% sulfuric acid solution (AC) and 1% sodium hydroxide solution (AK). Phenol formaldehyde (PF) prepolymers were prepared as a cross-linker of okara hydrolyzates. Then, okara-based adhesive resins were formulated with 35% AC, 35% AK and 30% PF prepolymer on solid content basis. The adhesive resins were applied on high-density fiberboards (HDF) with the spread rate of $300g/m^2$. After that, oak fancy veneers are covered on the HDF, and then pressed with the pressure of $7kg/m^2$ at $120^{\circ}C$. The experimental variables were three mole ratios of formaldehyde to phenol (1.8, 2.1, 2.4), three assembly time (0, 10, 20 min), and two press time (90 sec, 120 sec), respectively. The fancy-veneered high-density fiberboards were tested by dry tensile strength, glueline failure by wetting and formaldehyde emission. Tensile strength of the boards exceeded the requirement of KS standard. The formaldehyde emissions were approached at the E0 level specified in KS standard. Based on these results, okara can be used as an ingredient of environmentally friendly adhesive resin systems for the production of flooring boards.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.722-729
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• 1997

The study was undertaken to extend the shelf life of filleted and salted fishes such as mackerel and jacopever. These filleted and salted fishes were dehydrated by dewatering sheet containing sodium polyacrylate resin at $5{\pm}1^{\circ}C$, wrapped with low density polyethylene film, and then stored at $-18{\pm}2^{\circ}C$. During the frozen storage, the change of brown pigment formation, peroxide value, carbonyl value, drip formation content in the cold-osmotic dehydrated fishes after salt dipping were much lower than those of non-dehydrated ones. Moreover, the proteins and Ca-ATPase in the cold-osmotic dehydrated fishes after salt dipping were more stable than those of non-dehydrated ones during frozen storage. It was supposed that the cold-osmotic dehydration pretreatment processing for filleted and salted fishes was useful in improvement of the frozen storage stability.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.422-427
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• 1994

The quality of salted and semi-dried mackerel prepared by cold osmotic dehydration using a high osmotic pressure resin during storage at $5{\pm}1^{\circ}C$ was evaluated. The moisture contents in salted and semi-dried mackerel decreased in. range of 4 during storage. The brown pigment formation content and peroxide value of salted and semi-dried mackerel prepared by osmotic dehydration were more lower than those of salted and semi-dried mackerel prepared by traditional drying methods such as sun-drying, hot-air drying and cold air drying. The viable cell count and histamine contents of cold osmotic dried products were much lower and revealed a tendency to increase during storage, but even these values after storage of 15 days showed that the salted and semi-dried mackerel was safety in respect of food sanitation. The ratio of saline soluble nitrogen to total nitrogen in cold osmotic dried products were higher than that of traditional dried products during storage. Judging from the results of chemical and sensory evaluation, shelf-life of salted and semi-dried mackerel by cold osmotic drying were more longer than that of salted and semi-dried mackerel prepared by traditional drying.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.775-779
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• 2002

Barley brans, divided into fractions I $(pearlers\;1{\sim}4)$, II $(pearlers\;5{\sim}20)$, and III $(pearlers \;21{\sim}24)$, germ, and broken kernels were collected as pearling by-products produced by an industrial process consisting of 24 consecutive barley pearlers. The pearling by-products were extracted with 75% ethanol, and polyphenol extracts were separated using Sepabeads SP-850 resin. Total polyphenol content was the highest (43.68%) in the polyphenol extract separated from fraction I. Polyphenol compounds analyzed by HPLC were tentatively identified as proanthocyanins and prodelphinidin polymers, which were known to have antioxidative and antimutagenic activities. Antioxidative abilities were estimated to be in the following order: fraction I>germ>fraction II>fraction III. At 0.01% polyphenol extract, angiotensin I-converting enzyme inhibitory activity was the highest in the germ fraction (40.04%). Nitrite-scavenging activity was over 70% in all fractions. Superoxide dismutase-like activity was in the range of $64{\sim}78%$ in fractions I and II.

• Korean Journal of Agricultural Science
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• v.32 no.1
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• pp.19-27
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• 2005

This study was performed to evaluate the physical and mechanical properties of polymer concrete using unsaturated polyester resin, initiator, heavy calcium carbonate, crushed gravel, recycled coarse aggregate, silica sand and recycled fine aggregate. The unit weight, compressive strength, flexural strength and dynamic modulus of elasticity were decreased with increasing the content of recycled aggregate. The unit weight, compressive strength, flexural strength and dynamic modulus of elasticity were showed in $2,127{\sim}2,239kg/m^3$, 80.5~88.3MPa, 19.2~21.5MPa and $254{\times}10^2{\sim}288{\times}10^2MPa$ at the curing age 7 days, respectively. Therefore, these recycled aggregate can be used for polymer concrete.

• Polymer(Korea)
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• v.24 no.3
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• pp.389-398
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• 2000

Transparent, abrasion resistant coatings with 4~13 ${\mu}{\textrm}{m}$ thickness were prepared by spin-coating on polycarbonates with organic/inorganic hybrid solutions, followed by UV curing and heat treatment at 12$0^{\circ}C$ for 12 hours. The coating solutions were composed of inorganic phase and organic phase in 0:100, 20:80, 30:70, 50:50, 80:20 wt% ratios, respectively, mixed with photoinitiator, senaitizer and surfactant. The inorganic phase was formed by sol-gel reaction of TEOS and silane coupling agent MPTMS in 1 : 2 or 2 : 1 molar ratios, the organic phase consisted of difunctional urethane acrylate oligomeric resin, multifunctional acrylate TMPTA and HDDA in 4 : 3 : 3 wt% ratio. The coating systems were investigated by FT-IR, $^{29}$ Si-NMR spectra. In addition, TGA/DSC for thermal analysis and SEM, AFM observation for coated surface were examined. Gererally, the homogeneity of phases, the surface smoothness of coating and abrasion resistance were improved with the higher content of inorganic component. Namely, coating system with below 10 $\AA$ surface roughness and T$_{g}$ of 15$0^{\circ}C$ showed only 10% decrease in light transmittance after abrasion test, whereas uncoated polycarbonate substrate exhibited 46% decrease..

• Journal of the Korean Wood Science and Technology
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• v.9 no.3
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• pp.16-23
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• 1981

This study has been carried out to make a comparative study for the adhesive control methods specifically developed for application to formaldehyde. The method for formaldehyde determination used in this report is the improved chromo tropic acid determination. The results are summarized as follows: 1. The soaking treatment in aqueous solution of urea wok the most scavenging effect on the formaldehyde release from a plywood sample glued with a urea formaldehyde adhesive, and other removal treatment such as resorcinol, albumine-, and hardener-treatment gave significant reduction too. 2. In glue shear strength of dry test, 2% of resorcinol treatment and soaking treatment showed the highest strength and all the other treatment met the standard, but in hot water soaking test, 2% of resorcinol treatment gave the best results, on the other hand, adding the hardener showed the lowest strength and failed in meeting the standard. 3. Air dried moisture content of all treated plywood met the standard which calls for 13% or bellow. 4. In this comparative study, we can make a strong combination each other or go into the details of one treatment for the best result through the more study.