• Journal of the Korean Applied Science and Technology
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• 제25권2호
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• pp.151-159
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• 2008

The flame-retardant coatings were prepared by blending the synthesized triphosphorus modified polyester in the previous paper and hexamethylene diisocyanate-trimer and curing it at room temperature. The characterization of the films of the prepared coatings was performed. It was confirmed that no deterioration of physical properties of PU coatings was observed with the increasing phenylphosphonic acid (PPA) contents. Flame retardancy was tested by a $45^{\circ}$ Meckel burner method and LOI method. With the $45^{\circ}$ Meckel burner method, CATBTP-20C and CATBTP-30C that contain 20 wt% and 30 wt% of PPA, flame retarding component, respectively, showed the first grade flame retardancy with $2.8{\sim}3.9\;cm$ of char length ; and, with LOI method, they exhibited a good flame retardancy as a range of $30{\sim}32%$ of combustion values.

• Resources Recycling
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• 제4권1호
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• pp.60-68
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• 1995

Iron-bearing dust which stems from steelworks were pelletized and bonded with portland cement in order to attempt to use for blast iurnace burdens. The characterist~cs of cold bonded dust pellet were investigated. It was found that the compression strength of cold bonded pellet contaning portland cement of 10 wt.% reached above 150kg/p by proper curing treatment. Direcl contad of carbon with iron oxides seems to greately enhance a reduction reaction and herewxth increased chances to lorn pores at high temperature environment. Tumbler strength, RDI, and swelling of cold bonded pellet were similiar to and/or better than those of iron ore sinter and fired pellet.

• Advances in concrete construction
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• 제11권4호
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• pp.307-314
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• 2021

Activated hwangtoh (ACT) is a natural resource abundant in South Korea, approximately 15.0% of soil. It is an efficient mineral admixture that has activated pozzolanic properties through high-temperature heating and rapid cooling. The purpose of this study is to improve a curb mixture that can reduce NOx outside and investigate durability performance. To this end, mortar curb specimens were manufactured by replacing OPC with ACT. The ACT substitution ratios of 0.0, 10.0, and 25.0% were considered, and mechanical and durability tests on the curb specimens were conducted at 28 and 91 days of age. Steam curing was carried out for three days for the production of curbs, which was very effective to strength development at early ages. The reduction in strength at early ages could be compensated through this process, and no significant performance degradation was evaluated in the tests on chloride attack, carbonation, and freezing and thawing. The mortar curb with an ACT of 10.0~25.0% replacement ratio exhibited clear NOx reduction through photocatalytic (TiO2) treatment. This is due to the increase in physical absorption through surface absorption and the photocatalyst-containing TiO2 coating. In this study, the reasonable range of the ACT replacement ratio for NOx reduction was quantitatively evaluated through a comprehensive analysis of each test.

• Journal of the Korea Institute of Building Construction
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• 제15권1호
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• pp.25-33
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• 2015

In this study, initial crack index was evaluated by FEM analysis to find the crack propagation from hydration heat in precast concrete. As results, as the usage of hardening accelerator increased, initial compressive strength increased and setting time was shortened. Additionally, as amounts of hardening accelerators increased, the central temperature of concrete increased and the time to reach the highest temperature was shortened. It was demonstrated that the hardening accelerators accelerated the hydration reaction of cement, and caused the increase of hydration heat within the short period of time. Furthermore, the crack index for evaluating the heat level was performed by FEM. As results, there was no problem about the cracks, despite of the growth of initial high hydration heat. This is because of the increased tensile strength that is large enough to sustain the thermally induced-stress.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.345-348
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• 2008

A Cement account for the most amount than other materials in the material composition of ultra-high-performance concrete. If we especially consider the effect of high temperature curing on the cement hydration and the problems of autogenous shrinkage, heat of hydration we need selection of proper cement type by grasping influence of cement in the properties of UHPC. Therefore, in this paper we examined properties of fluidity, compressive strength and elastic modulus of UHPC due to domestic portland cement types. In results, we could get a result that the low heat cement increase fluidity, compressive strength in UHPC compare with high early strength cement and ordinary portland cement. we are systematically going to examination on the influence of UHPC by domestic portland cement types.

• Applied Chemistry for Engineering
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• 제32권4호
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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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• 제49권1호
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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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• 제28권2호
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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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• 한국건축시공학회 2002년도 학술.기술논문발표회
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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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• 제25권2호
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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].