• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.30-37
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• 2001

Generally, polymer mortar made with unsaturated polyester(UP) resin has a high curing shrinkage. This is an inadequate as repair material and construction products that have been widely used for years recently. To overcome these problems, polymer researchers and engineers have used shrinkage-reducing additives, which are usually specific thermoplastic polymers. The objective of this study is to evaluate the effects of shrinkage-reducing additive on the curing shrinkage and strengths of UP mortar. UP mortars are prepared with expanded polystyrene(EPS) ratio in styrene monomer(SM), (EPS/PS, PS=EPS+SM), and the ratio of total polystyrene resin(PS) to UP resin, (PS/UP). And it is tested for viscosity of UP resin, slump-flow, working life, flexural and compressive strengths, and curing shrinkage tests. From the test results, viscosity of resin for UP mortar increases with increasing PS content. Curing shrinkage of UP mortar is considerably smaller than that of plain UP mortar, nevertheless, reduction in the strengths is not recognized according to adding PS resin. In this study, we can obtain the optimum mix proportions of UP mortar using PS resin which made of waste expanded polystyrene.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1988.11a
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• pp.49-56
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• 1988

자동차의 동력전달 수단으로 사용되는 클러치는 그 기능에 따라 수동식과 자동식으로 구분된다. 전자의 경우 transmission과 engine의 동력을 dry contact mechanism으로 단속 제어하는 반면 후자는 hadraulic torque drive와 engine의 동력을 transmission box내의 기어유에 의한 wet contact mechanism으로 단속 제어한다. 자동식 클러치에 사용되는 paper facing은 cellulose fiber를 기본으로 하여 열경화성 수지 및 무기충진제등을 함유하고 있으나, 특히 무기충진제의 종류 및 첨가량이 paper facing의 마찰특성에 크게 영향을 미친다. 본 연구는 목재펄프(wood pulp), 린터펄프(linter pulp)등의 펄프를 주체로 하고 열경화성 수지와 무기충지제등을 첨가한 마찰재를 제조하여 무기충진제들의 마찰특성에 미치는 영향을 조사함으로써 paper facing의 기초 자료를 얻는데 그 목적이 있다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.05a
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• pp.170-170
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• 2001

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.339-340
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• 2009

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.439-444
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• 2015

Several attempts to design the best-available thermosetting road markings by using MMA to improve the durability and retroreflectivity are presented in this paper. In order to improve field applicability, the components of main materials were designed by means of reducing the hardening time lower than eight minutes. The optimum mixing ratio of thermosetting road marking was TSRM-6 composed of 15.6 wt% of MMA monomer ($Tg=105^{\circ}C$), 6.0 wt% of PMMA (MW = 70,000, $Tg=60^{\circ}C$) and 1.2 wt% of TMPTA (MW = 338, $Tg=27^{\circ}C$). Also the homogeneous mixing of all components was necessary. The use of ceramic glass beads with an optimized TSRM-6 exhibited excellent performance by achieving retroreflectivity coefficients of 431, 354 and $172mcd{\cdot}m^{-2}{\cdot}lux^{-1}$ for dry, wet and rainy test condition, respectively at two hundred thousand cycles.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.1059-1066
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• 2009

Recently, the amount of thermosetting plastic wastes has increased with the production of reinforced plastic composites and causes serious environmental problems. The epoxy resins, one of the versatile thermosetting plastics with excellent properties, cannot be melted down and remolded as what is done in the thermoplastic industry. In this research, a series of experiments that decompose epoxy resin and recover carbon fibers from carbon fiber reinforced epoxy composites applied to railway vehicles was performed. We experimentally examined various decomposition processes and compared their decomposition efficiencies and mechanical property of recovered carbon fibers. For the prevention of tangle of recovered carbon fibers, each composites specimen was fixed with a Teflon supporter and no mechanical mixing was applied. Decomposition products were analyzed by scanning electron microscope (SEM), gas chromatography mass spectrometer (GC-MS), and universal testing machine (UTM). Carbon fibers could be completely recovered from decomposition process using nitric acid aqueous solution, liquid-phase thermal cracking and pyrolysis. The tensile strength losses of the recovered carbon fibers were less than 4%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.24-30
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• 2018

Various investigations of vegetable oil extracted from natural resources are underway because of their low cost and environmental value. On the other hand, the double bonds in vegetable oil should be substituted to other high reactive functional groups due to their low reactivity for synthesizing bio-polymeric materials. ${\alpha}$-eleostearic acid, which consists of a conjugated triene, is the main component of tung oil, and the conjugated triene allows tung oil to have higher reactivity than other vegetable oils. In this study, tung oil was copolymerized with styrene and divinylbenzene to make a thermoset resin without any substitution of functional groups. The thermal and mechanical properties were measured to examine the effects of the composition of each monomer on the synthesized thermoset resin. The results showed that the products have only one Tg, which means the synthesized thermoset resins are homogeneous at the molecular level. The mechanical properties show that tung oil acts as a soft segment in the copolymer and makes a more elastic product. On the other hand, divinylbenzene acts as a hard segment and makes a more brittle product.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.269-270
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• 2011

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.191-202
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• 1998

The maturity method in which the strength increase of cement concrete is expressed as a function of an intergral of the curing period and temperature of the concrete has often been applied to its strength prediction. For the purpose of the application of the maturity method to the compressive strength prediction for lightweight polymer mortars using an unsaturated polyester resin as a binder, the lightweight polymer mortars with various catalyst and accelerator contents, are prepared. tested for compressive strength, and the datum temperatures for the maturity equations are estimated. The maturity is calculated by using the maturity equations with the estimated datum temperature. The compressive strengths of the lighweight polymer mortars are predicted from the maturity-compressive strength relationships.

• Composites Research
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• v.32 no.6
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• pp.349-354
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• 2019

The Aluminum conductor composite core consists of fast-curing thermosetting epoxy used as reinforcements and carbon fiber and glass fiber used as matrix. In this study, we have investigated fast curing epoxy cured products used for composite core(Aluminum Conductor Composite Core, ACCC). Tetrafunctional epoxy(PA 806) was used as a multifunctional epoxy, along with two kinds of curing agents, MNAn(5-Methyl-5-norbornene-2,3-dicarboxylic anhydride) and HHPA(Hexahydrophthalic Anhydride), to make an epoxy cured product and their properties were evaluated. Optimum conditions are confirmed by varying the content of curing accelerator in the selected epoxy and curing agent.