• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.2
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• pp.116-127
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• 2003

The Tak flux measurement (TFM) site, one of the sites of Korean Flux Network (KoFlux) which is an infrastructure of AsiaFlux, is constructed at a northwest of Thailand. The eddy covariance technique is used for measuring energy, water and carbon dioxide ($CO_2$) fluxes, and a real time monitoring and simulation system (RTMASS) developed for data acquisition and processing. The RTMASS is the core structure of the KoFlux-data information system (KoFlux-DIS) and consisted of a remote and a local system. Data acquisition and transmission, and data storage, processing and publishing are functions of those systems, respectively. As primary results about the characteristics of mean flow and turbulence analysis, TFM is a proper site to measure and analyze the various fluxes and those budgets on tropical deciduous forest.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.706-713
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• 2011

The effects of silica-alumina type catalysts addition on the thermal decomposition of ethylene vinyl acetate (EVA) resin have been studied in a thermal analyzer (TGA, DSC) and a small batch reactor. The silica-alumina type compounds tested were kaolinite, bentonite, perlite, activated clay and clay. As the results of TGA experiments, pyrolysis starting temperature for EVA resin had the 1st pyrolysis temperature range of 300~$400^{\circ}C$ and the 2nd pyrolysis temperature range of 425~$525^{\circ}C$. The silica-alumina type catalysts did not affect the pyrolysis rate in EVA pyrolysis reaction. In the DSC experiments, addition of kaolinite and bentonite catalysts reduced the heat of fusion and heat of 2nd pyrolysis reaction. In the batch system experiments, the mixing of silica-alumina type catalysts enhanced the yield of fuel oil, and affected to the distribution of carbon numbers. In the silica-alumina type inorganic material used in this experiments, bentonite was the most effective from the pyrolysis heat, yields, and the characteristics of fuel oil.

• Journal of Adhesion and Interface
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• v.2 no.3
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• pp.1-8
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• 2001

Epoxy composites filled with natural zeolite was prepared to investigate the effects of silane coupling agent, ${\gamma}$-APS (${\gamma}$-aminopropyltriethoxysilane)on the surface free energy, tensile properties and interfacial morphology. The value of Lifshitz-van der Waals component, ${\gamma}{\frac{LW}{SV}}$ for polar was $19.22mJ/m^2$ and increased, while that of Lewis acid-base component, ${\gamma}{\frac{AB}{SV}}$ for polar was $15.27mJ/m^2$ and decreased with the increasing content of ${\gamma}$-APS treatment. It is due that the surface of the zeolite is more coated by hydrophobic of alkyl group than hydrophilic amine or hydroxyl group. The tensile strength and Young's modulus of epoxy system were improved by the treatment with ${\gamma}$-APS due to the strong interface bonding, which was confirmed by SEM.

• Elastomers and Composites
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• v.40 no.1
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• pp.3-11
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• 2005

The ruling kinetics of epoxy resins with 3 different kinds or alkenylsuccinic anhydride (ASA) having C-8, C-12, and C-16 pendant side chain length with two different catalysts was studied by using differential scanning calorimetry (DSC). Nonisothermal and isoconversional method has been used for characterizing the effect of the pendant side chain length in the curing process. Results or nonisothermal method showed that there was no significant difference in the effect of the pendant side chain length of ASA. But isoconversional analysis showed that the value of the activation energy for the initiation reaction or C-8, C-12, and C-16 were $61.7{\sim}57.7kJ/mol$, $63.0{\sim}57.3 kJ/mol$, and $130.4{\sim}94.2 kJ/mol$, respectively, depending on the catalyst used. The values of activation energy for the initiation is different as reported value of 20 kJ/mol which indicating the difference in the effect of the pendant side chain length of ASA in the initial stage of the reaction.

• Elastomers and Composites
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• v.43 no.1
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• pp.18-24
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• 2008

An oligomeric diol was utilized as a modifier for the reaction rate and mechanical properties of a RT-castable polyurethane elastomer. Both the reaction rate and the tensile strength of the blend samples, in which the modifier and the base resins were mixed with one-shot method, showed an exponential decrease as the increase of modifier concentration. Thermal analysis method of Kissinger was also effectively applied in the present study, showing good linearity in the plot of ln $(q/T^2_p)$ vs. $(1/T_p)$ and activation energy $E_a$ of 44.80 kJ/mol, which is similar to the general castable polyurethane. In the mechanical properties, remarkable decrease of strength was found by the addition of modifier concentration range up to about 20 phr, while characteristic elongation property of the elastomer, high elongation at lower strength, was observed over 20 phr of the modifier. Exponential decrease of the break strength of the blend sample exhibited that the mechanical properties of the blend might be considerably sensitive to the modifier concentration.

• Korean Journal of Materials Research
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• v.29 no.4
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• pp.221-227
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• 2019

This study examines the role of the nano- and micro-particle ratio in dispersion stability and mechanical properties of composite resins for SLA(stereolithography) 3D printing technology. VTES(vinyltriethoxysilane)-coated $ZrO_2$ ceramic particles with different nano- and micro-particle ratios are prepared by a hydrolysis and condensation reaction and then dispersed in commercial photopolymer (High-temp) based on interpenetrating networks(IPNs). The coating characteristics of VTES-coated $ZrO_2$ particles are observed by FE-TEM and FT-IR. The rheological properties of VTES-coated $ZrO_2/High-temp$ composite solution with different particle ratios are investigated by rheometer, and the dispersion properties of the composite solution are confirmed by relaxation NMR and Turbiscan. The mechanical properties of 3D-printed objects are measured by a tensile test and nanoindenter. To investigate the aggregation and dispersion properties of VTES-coated $ZrO_2$ ceramic particles with different particle ratios, we observe the cross-sectional images of 3D printed objects using FE-SEM. The 3D printed objects of the composite solution with nano-particles of 80 % demonstrate improved mechanical characteristics.

• Journal of Adhesion and Interface
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• v.23 no.3
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• pp.59-69
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• 2022

In composite materials, the adhesion and interfacial properties were the most important factors to obtain high performance of mechanical properties. This review paper had been focused on the micromechanical evaluation methods for the interfacial property historically. The interfacial property of fiber-reinforced composites (FRC) could be evaluated using only a single fiber and matrix via various micromechanical testing methods. Self-sensing due to the fracture behavior of FRC could be determined and discussed more critically and clearly using electro-micromechanical evaluation. In this paper, the research trends for micro-mechanical evaluation of composites was summarized, and their practical applications would be suggested in the future.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.3
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• pp.310-317
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• 2024

In this study, Aimed to develop technology to ensure the safety of firefighters responding to hydrogen incidents and to review the performance of protective super absorbent polymer (SAP) that could help maintain the thermal protection performance of equipment with protective properties. Tests were conducted, including bench-scale and full-scale thermal exposure tests, to review the protective performance of SAP using firefighting garments commonly used by firefighters. The results showed that without SAP application, 2nd degree burn areas were measured at 9.4%, and 3rd degree burn areas at 7.7%. In contrast, when SAP was applied, the percentage of 2nd degree burn areas decreased to 7% on the lower body, and there was no temperature rise causing 3rd degree burns. Therefore, it is expected that by applying SAP to the outer surface of firefighter garments, even under temporarily high temperature conditions such as hydrogen jet flames, thermal damage to firefighters could be protected for a certain period.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.75-80
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• 1994

Flexural properties and thermal stability have been studied as a function of blend composition in bifunctional DGERA (diglycidyl ether of hisphenol A)/tetrafunctional TGDDM(tetrag1ycidyl diamino diphenyl methane) cured with DDM(4, 4'-diamino diphenyl methane). The flexural modulus and the glass transition temperature increase with an increase of TGDDM and show discontinuous dependence on blend composition around the composition range of 80/20~60/40(L)GEBA/TGDDM). This can be explained with a structural phase inversion (ductile-to-brittle) in crosslinking networks. With increasing TGDDM, the maximum decomposition temperature(Ts) increases, whereas the activation energy during thermal degradation decreases.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.4
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• pp.366-371
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• 2011

The sea squirt Halocynthia roretzi is mainly cultured in Tongyeong, Southern coastal area of Korea. This study presents the physiological rates of respiration, excretion, feeding and assimilation efficiency of the sea squirt Halocynthia roretzi to analyze the SFG(scope for growth) and net growth efficiency, determined during 2007. Oxygen consumption and nitrogen excretion rates increased with a rise in temperature during the summer period whereas feeding rates decreased. The O:N ratio was high during winter(October to February). Assimilation efficiency showed an annual average of 75.4% during the experimental period, except during a period of elevated temperature in July to September(average $25^{\circ}C$). Net growth efficiency($K_2$) was 8.7 to 64.2% except for May to September, when temperature increased at the aquaculture farm. SFG was negative from May to September, reflecting high temperatures and low feeding rates during this period; its highest positive values occurred during winter.