• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.449-455
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• 2021

Composite materials are substances that are configured to have excellent physical properties by combining the properties of a single substance, and are in the limelight as materials that exceed the performance of metals and polymers. However, it has the disadvantages of long cycle time and high unit price, and much research is being performed to overcome these disadvantages. In this study, we developed an epoxy resin curing agent that can shorten the time required for mass production of composite materials, and tried to expand the applicability of objections by imparting flame retardancy. The epoxy resin used as a basic substance utilized two types of bisphenol F and resorcinol structure, which was further modified using 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide (DOPO) to impart flame retardancy. Triethylphosphate (TEP) and bis [(5-ethyl-2-methyl-1,3,2-dioxaphosphorinan-5-yl)methyl] methyl phosphonate P,P'-dioxide (FR-001) were used as additives, seven kinds of compositions were blended, thermal characteristics (gelation time, glass transition temperature) and flame retardant performance were evaluated. We successfully developed an epoxy matrix that can be applied to high pressure resin transfer molding (HP-RTM) process.

• Elastomers and Composites
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• v.49 no.1
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• pp.59-65
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• 2014

In this study, in order to complete curing reaction of the molding compound comprising an epoxy/anhydride at $71^{\circ}C$ for 40 hours, metal coordination complexes such as cobalt (II) acetylacetonate, potassium acetylacetonate, iron (III) acetylacetonate and chromium (III) octoate as a catalyst were applied to the epoxy/anhydride compounds respectively. The weight ratio of an epoxy part/an anhydride part was adjusted to improve the mechanical properties of the molding compound. According to the experimental results, an epoxy/anhydride compound containing chromium (III) octoate showed a high conversion at $71^{\circ}C$ for 40 hours as well as a proper processability at room temperature among the several metal coordination complexes. For the mechanical properties of the cured epoxy/anhydride compound, the compounds containing weight ratio from 0.9/1 to 0.5/1 of the epoxy part/anhydride part with chromium (III) octoate showed the high flexural strength, and higher compressive strength was shown with increasing of the hardener part.

• Textile Coloration and Finishing
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• v.28 no.2
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• pp.70-76
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• 2016

Silver nanoparticles(AgNPs) were attached to wool fibers using glycidyltrimethylammonium chloride(GTAC), which is a type of quaternary ammonium salt. GTAC, which contains an epoxy functional group that, under high temperatures, generates a ring-opening reaction with wool fibers, which contain the amine group. Then, the AgNPs are attached to the surface of the GTAC-treated wool fibers by treatment with a silver colloidal solution. The process involves the following procedures: (1) The wool fibers are immersed in the GTAC solution, followed by pre-drying at $80^{\circ}C$ and curing at $180^{\circ}C$ to induce an alteration in the chemical structure; and (2) The wool fibers treated with GTAC are immersed in the silver colloid at $40^{\circ}C$ for 120 min to chemically induce a strong attachment of the AgNPs to the wool fibers. Scanning electron microscopy was used to analyze the influence of the concentrations of GTAC and the silver colloid, as well as the influence of the applied temperature of the silver colloid on the wool fibers, and the influence of the morphological changes in the wool fiber surfaces. As a result, the enhanced concentrations of GTAC and the silver colloid together with an elevated applied temperature of silver colloid have a tendency to increase in Ag atomic%.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.11a
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• pp.87-91
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• 2002

This paper investigates the corrosion inhibition and the reduction of hydration heat properties of Ground Granulated Blast-Furnace Slag (GGBFS) added concrete. Since the massive civil structure is vulnerable to the thermal crack by hydration. adiabatic temperature rising tests were performed for water-binder ratios from 43.2% to 47.3%, while replacing 15% to 50% of cement with GGBFS of equal weight. Then, the corrosion protection performance was evaluated using cylindrical specimens embedded with steel reinforcement according to the combination of 3 W/B ratios and 2 levels of chloride ion quantity. The corrosion area of the embedded steel ban was determined using the high pressure steam curing method specified in KS F 2561. The test results showed that the replacement of GGBFS was effective in reducing the hydration heat. The corrosion area of the embedded steel ban decreased as the replacement of GGBFS increased. However, the corrosion area of the steel bar was proportional to the autoclave cycle and the chloride ion quantity. Among the tested specimens, compressive strength, reduction of hydration heat, and corrosion inhibition performance were excellent when 50% of cement was replaced with GGBFS of equal weight.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.2
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• pp.10-18
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• 2011

In order to develop highly-integrated RGBY(Red, Green, Blue, Yellow) LED light, a high thermal radiation ceramic package was manufactured, and the encapsulation process was applied with a vacuum printing encapsulation system(VPES). After the completion of vacuum printing, the shape of the encapsulation layer could be controlled by heat treatment during the curing process, and the optical power became highly increased as the encapsulation layer approached a dome shape. The optical characteristics involved in a Correlated Color Temperature(CCT), a Color Rendering Index (CRI), and the efficiency of RGBY LED light were able to be identified by the experimental designing method. Regarding the characteristics of the white light of RGBY LED light, which were measured on the basis of the aforementioned optical characteristics, CRI posted 88, CCT recorded 5,720[$^{\circ}K$], and efficiency exhibited 52[lm/W]. The chip temperature of RGBY LEDs was below 55[$^{\circ}C$] when the consumption power of LED chips was 0.1[W] for the red, 0.3[W] for the green, 0.08[W] for the blue, and 0.24[W] for the yellow. Also, the thermal resistance of the highly-integrated RGBY LED light measured by T3Ster was 2.3[K/W].

• Textile Coloration and Finishing
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• v.27 no.2
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• pp.119-125
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• 2015

The effects of e-beam irradiation on water-repellency and washing durability of water-repellent finished chemically-recycled PET(CR-PET) fabrics were investigated. As results, more doses of e-beam irradiation damaged the fabric surface more severely. It was thought because the high densed energy was formed, where the more e-beam was converged. The contact angle measurement showed that as the dose of e-beam irradiation increased, water wettability of the CR-PET fabric increased slightly. It was thought to be due that the surface etching by e-beam irradiation let water droplet permeate into the fabric surface better. The concentration of the water-repellent finishing agent was more important factor than curing temperature as finishing parameter. It was considered because the water-repellent finishing agent used in this study got to cure sufficiently at low temperature. Consequently, e-beam irradiation improved the washing durability of water-repellent finishing on the CR-PET fabrics.

• Polymer(Korea)
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• v.34 no.1
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• pp.52-57
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• 2010

The low viscous epoxy resin(bisphenol F) with carboxylic acid as the reductants was introduced for high performance and reliability in the ACA with a low melting point alloy filler system. The curing characteristics of the epoxy resin and temperature dependant viscosity characteristic of epoxy resin at the melting temperature of LMPA were investigated by dynamic mode of differential scanning calorimetry (DSC) and rheometer, respectively. Based on these thermo-rheological characteristics of epoxy resin and LMPA, the optimum process system was designed. In order to remove the oxide layer on the surface of LMPA particle, three different types of carboxyl acid-based reductant were added to the epoxy resin. The wetting angles were about $18^{\circ}$ for carboxypropyldisilioxane, and $20.3^{\circ}$ for the carboxy-2-methylethylsiloxane, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.760-767
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• 2016

Food waste (FW) has been recognized as a critical problem in Korea and many research was conducted to efficiently utilize or treat FW. Main purpose of this research was to evaluate a feasibility for producing fermented organic fertilizer with vegetable waste (VW). Three different organic materials (saw dust, coco peat, and waste mushroom media) were mixed with VW at the rate of 30, 40, 50% respectively. Total days of composting experiment were 35 days and each sub samples were collected at every 5 days from starting of composting. Result showed that inner temperature of composting was increased to $60{\pm}4^{\circ}C$ within 5~10 days depending on varied organic materials and mixing ratio. Among different treatment, the highest increase of inner temperature was observed when 30% of saw dust was mixed with VW. After finishing composting experiment, maturity of each compost was evaluated with solvita and germination test. Maturity index (MI) of each treatment was ranged between 5~7 indicating that manufactured fertilizer was curing or finished stage. Calculated germination index (GI) was at the range of 57.83~101.16 depending on organic materials and mixing ratio. Both MI and GI showed that manufactured fertilizer was met for fertilizer criteria while control (VW only) was not adequate for composting. Overall, VW can be utilized for making organic fertilizer mixing with saw dust, coco peat and more research should be conducted to make high quality of organic fertilizer with vegetable waste.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.574-584
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• 2003

The most common deterioration cause of concrete structures in urban environment is carbonation. Recently, the $CO_2$ concentration and temperature at atmosphere is sharply increased with time due to global warming phenomena. In this study, the climate scenario IS92a, which was suggested by the IPCC, is used to consider temperature and atmospheric $CO_2$ concentration change in the model of service life prediction. The modified mathematical solution, which was based on the Fick's 1st law of diffusion, was used to reflect concrete materials properties such as the degree of hydration of concrete with elapsed time, and important parameters, which associated with deterioration rate. The techniques of service life prediction are developed introducing the method of reliability and stochastic concept to consider microclimatic condition in Seoul, South Korea. From the result of service life prediction, concrete containing high W/C ratio is shown fast carbonation rate due to $CO_2$ concentration increase. It is concluded that the deterioration of concrete structures due to carbonation is insignificant problem on the conditions that below W/C 55%, well curing concrete.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4756-4762
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• 2014

Damaged wind turbine blades are repaired conventionally using a hand lay-up method with epoxy, where the bonding strength is not high. Epoxy has poor curing characteristics at low temperatures. The infusion method with polyester was proposed. Infusion method is believed to distribute resin uniformly. Polyester is used because it hardens better than epoxy at low temperatures. At room temperature, the proposed method increased the bonding strength by 77.7% compared to the conventional method. Using the proposed method at 15 and $5^{\circ}C$, the bonding strength increased compared to the conventional method. This paper proposes a new method for repairing wind turbine blades, even at temperatures where the conventional method cannot be used because epoxy resin does not harden. The bonding strength of the proposed method at low temperatures is higher than that of the conventional method at room temperature.