• Polymer(Korea)
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• v.33 no.5
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• pp.477-484
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• 2009

Suspension polymerization with hydrophobic silica as a stabilizer and AIBN as an initiator was conducted to synthesize PBMA particles and PBMA composite particles containing carbon black. Surface modification of silica particles by controlling pH revealed that 90% of them functioned as stabilizer and 10% were incorporated into PBMA particles. While stabilizer concentration had no impact on reaction kinetics and particle diameter, an increase in stabilizer concentration displayed an increase in molecular weights when it exceeded 1.67 wt%. An increase in initiator concentration and reaction temperature decreased molecular weights in close agreement with the theoretical equation. An increase in carbon black concentration from 1 to 7 wt%, relative to the monomer, showed a progressive decrease in reaction conversion. As carbon black was increased from 3 to 5 wt%, glass transition showed a $4^{\circ}C$ increase. The presence of carbon black was confirmed by TEM while its concentration was measured by TGA.

• Elastomers and Composites
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• v.43 no.3
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• pp.157-165
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• 2008

Suspension polymerization was carried out to synthesize poly(butyl methacrylate) (PBMA) composite particles containing carbon black. Water was selected as a reaction medium, hydrophobic silica as a stabilizer and azobisisobutyronitrile as an initiator. Concentration of stabilizer was varied from 0.67 to 2.55 weight% with respect to the water, and that of initiator was varied from 0.25 to 3.00 weight% with respect to the butyl methacrylate (BMA) monomer. All polymerization reactions were conducted at 75$^{\circ}C$. It is found that stabilizer concentration has no impact on reaction kinetics, while an increase in initiator concentration enhances polymerization reaction rate. Increase of carbon black concentration from 1 to 3 to 5 wt% into PBMA displayed progressive decrease in reaction conversion. The particle diameter of PBMA composite particles containing carbon black was found to be between 5 and 30 ${\mu}m$. Glass transition was determined to range from 23.8 to 24.7$^{\circ}C$, irrespective of variation in the concentration of stabilizer, initiator or carbon black.

• Carbon letters
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• v.14 no.2
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• pp.105-109
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• 2013

Effects of the amount of nickel powder (Ni) in Ni-carbon fiber (CF) hybrid filler systems on the conductivity(or resistivity) and thermal coefficient of resistance (TCR) of filled high density polyethylene were studied. Increases of the resistivity and TCR with increasing Ni concentration at a given hybrid filler content were observed. Using the fiber contact model, we showed that the main role of Ni in the hybrid filler system is to decrease the interfiber contact resistance when Ni concentration is less than the threshold point. The formation of structural defects leading to reduced reinforcing effect resulted in both a reduction of strength and an increase of the coefficient of thermal expansion in the composite film; these changes are responsible for the increases of both resistivity and TCR with increasing Ni concentration in the hybrid filler system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.231-233
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• 2011

Carbon dioxide in atmosphere causes concrete carbonation which is the phenomenon, that is, the pH of concrete changes from 12-13 to 8.85-10. Even though the carbon dioxide concentration of indoor is higher than that of outdoor, the micro measurement has not carried out. The concentration of carbon dioxide was measured in three places. The data was used as boundary condition to FEM analysis for expectation of concrete carbonation depth. The affect of building finish materials to concrete carbonation was discussed.

• Analytical Science and Technology
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• v.8 no.4
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• pp.643-648
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• 1995

Cyclic voltammetric method is used to survey microscopic environments which take place at the surfactant-modified carbon electrode when the hydrophobic and hydrophilic environments of $Ru(ph){_3}^{2+}$(tris 1,10-phenanthroline ruthenium(II) chloride) is created by the addition of anionic surfactant, sodium dodecyl sulfate(SDS). Critical micelle concentration(CMC) of SDS in $Ru(ph){_3}^{2+}$ measured by cyclic voltammetry(CV) is in aggrement with that by surface tensiometry. Influence of the concentration of supporting electrolyte at surfactant-modified carbon electrode is investigated.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.6
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• pp.282-286
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• 2021

Penetration depth and compressive residual stress of laser-carburized TiZrN coating by thickness of carbon paste were investigated in terms of carbon potential. The carbon paste was covered with a thickness of 1.1 mm using screen printing, and applied to a thickness of 0.4 mm using spin coating, and laser carburization was performed under the same conditions. As the thickness of carbon paste increased, the diffraction pattern of the laser-carburized TiZrN coating shifted to a lower angle, indicating solid solution strengthening and lattice distortion. For microstructure analysis using TEM, the defects and carbon concentration of the laser-carburized TiZrN coating increased as the carbon paste was thicker. It indicated that the variation of the carbon potential corresponds to the change in the paste thickness. In XPS depth profile analysis, high concentration of carbon and formation of carbide were observed in laser-carburized TiZrN coating with thick carbon paste. It revealed that the carbon concentration on the surface and carbon potential were changed by the thickness control of carbon paste. The compressive residual stress increased from 3.67 GPa to 4.58 GPa by the variation of carbon concentration.

• Corrosion Science and Technology
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• v.18 no.4
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• pp.129-137
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• 2019

CFRP (Carbon Fiber Reinforced Plastics) is composed of carbon fiber and plastic resin, and is approximately 20 - 50% lighter than metallic materials. CFRP has a low density, higher specific stiffness, specific strength, and high corrosion resistance. Because of these excellent properties, which meet various regulation conditions needed in the industrial fields, CFRP has been widely used in many industries including aviation and ship building. However, CFRP reveals water absorption in water immersion or high humidity environments, and water absorption occurs in an epoxy not carbon fiber, and can be facilitated by higher temperature. Since these properties can induce volume expansion inside CFRP and change the internal stress state and degrade the chemical bond between the fiber and the matrix, the mechanical properties including bond strength may be lowered. This study focused on the effects of NaCl concentration (0.01 - 1% NaCl) and solution temperature ($30-75^{\circ}C$) on the galvanic corrosion between CFRP and A516Gr.55 carbon steel. When NaCl concentration increases 10 times, corrosion rate of a specimen was not affected, but that of galvanic coupled carbon steel increased by 46.9% average. However, when solution temperature increases $10^{\circ}C$, average corrosion rate increased approximately 22%, regardless of single or galvanic coupled specimen.

• Korean Journal of Optics and Photonics
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• v.35 no.2
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• pp.71-80
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• 2024

We developed a Raman lidar system for remote measurement of carbon dioxide present in atmospheric space. An air-cooled laser with 355-nm wavelength and a 6-inch optical receiver was used to miniaturize the Raman lidar system, and a scanning Raman lidar system was developed using a two-axis scanning device and a photon counter. To verify the performance of the developed Raman lidar system, a gas chamber capable of maintaining a concentration was located at a distance of about 87 m, and the change in Raman signal according to the change in the concentration of carbon dioxide was measured. As a result, it was confirmed that the change in the Raman scattering signal of carbon dioxide that appeared for a change in carbon dioxide concentration from about 0.67 to 40 vol% was linear, and the coefficient of determination (R²) value, which indicates the correlation between the carbon dioxide concentration and Raman scattering signal, showed a high linearity of 0.9999.

• Journal of the Korean GEO-environmental Society
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• v.23 no.12
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• pp.55-61
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• 2022

Carbon dioxide is one of the greenhouse gases in the atmosphere and much research is underperforming in reducing carbon dioxide. Geological carbon dioxide storage is considered the primary technique for global warming prevention. So, technic development for storing carbon dioxide is required. Using surfactant is considered an effective material for geological carbon dioxide storage. However, research on using surfactants for carbon dioxide sequestration is not enough. In this study, a 2D micromodel experiment depends on the surfactant type (sodium dodecyl sulfate and sodium dodecylbenzene sulfonate), concentration and carbon dioxide injection rate. As result, geological carbon dioxide sequestration efficiency is increased according to surfactant concentration and carbon dioxide injection rate increase. However, efficiency no more increases after critical concentration and rate.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E2
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• pp.79-84
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• 2002

The objective of this study was to investigate the biodegradation of ethylene in an activated carbon biofilter inoculated with immobilized microbial consortium. The biofilter performance was monitored in terms of ethylene removal efficiency and carbon dioxide production. The biofilter was capable of achieving ethylene removal efficiency as much as 100% at a residence time of 14 min and an inlet concentration of 290 ppm. Under the same conditions, carbon dioxide with a concentration of up to 546 ppm was produced. Its was found that carbon dioxide was produced at a rate of 87 mg day$\^$-1/, which corresponded to a volume of 0.05 L day$\^$-1/. During operation with an inlet ethylene of 290 ppm, the maximum elimination capacity of the biofilter was 34 g of C$_2$H$_4$m$\^$-3/ day$\^$-1/. The biofilter could provide an attractive treatment technology for removing ethylene, an extremely volatile and slowly adsorbed compound.