• Macromolecular Research
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• v.17 no.4
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• pp.276-279
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• 2009

• Carbon letters
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• v.11 no.2
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• pp.90-95
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• 2010

Carbon materials such as graphite and graphene exhibit high electrical conductivity. We examined the electrical conductivity of synthetic and natural graphene powders after the chemical reduction of synthetic and natural graphite oxide from synthetic and natural graphite. The trend of electrical conductivity of both graphene (synthetic and natural) was compared with different graphite materials (synthetic, natural, and expanded) and carbon nanotubes (CNTs) under compression from 0.3 to 60 MPa. We found that synthetic graphene showed a marked increment in electrical conductivity compared to natural graphene. Interestingly, the total increment in electrical conductivity was greater for denser graphite; however, an opposite behavior was observed in nanocarbon materials such as graphene and CNTs, probably due to the differing layer arrangement of nanocarbon materials.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.556-560
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• 2009

Aggregation behavior of three kinds of benzindocarbocyanine dyes in aqueous methanol solution was studied by UV-Vis absorption spectrum. The results indicated that the three dyes all existed monomer-dimer equilibrium in aqueous methanol solution (concentration range $10^{−5}\;to\;10^{−6}$ M) at 25.0$\sim$41.0 ${^{\circ}C}$ for Dye 1, 28.0$\sim$49.0 ${^{\circ}C}$ for Dye 2 and 26.0$\sim$47.0 ${^{\circ}C}$ for Dye 3. The fundamental property of the three dyes as the dimeric association constant KD, the dimeric free energy ${\Delta$}G_D, the dimeric entropy ${\Delta$}S_D, and the dimeric enthalpy ${\Delta$}H_D were determined. The ${\Delta$}H_D of three dyes: Dye 1, Dye 2 and Dye 3 was -42.5, -15.1 and -18.9 kJ/mol, respectively. The experimental observations were the subject of a theoretical study including the ground-state geometries which were fully optimized using DFT at B3LYP/6-31G level. The effect of dye molecule structure on ${\Delta$}H_D was discussed by theoretical calculations.

• Journal of Environmental Health Sciences
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• v.20 no.2
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• pp.73-79
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• 1994

The effects of packing materials in the anaerobic reactor and inorganic chemicals in the synthetic wastewater on the anaerobic treatment during the start up period were investigated using anaeroic filter process. The Ringlace and Honeycomb tube as packing materials were used in the anaerobic reactors. The Ca$^{2+}$ and Fe$^{2+}$ ion concentration as inorganic chemicals contained higher 40 times and 100 times as compared to the control synthetic wastewater, respectively. A start up period 104 and 150 days were necessary to achieve loading rate of 0.37 and 0.74 kg-Toc/m$^3$.d in the anaerobic filter process packed by Ringlace and Honeycomb tube, respectively. The loading rates of the reactor using the synthetic wastewater containing Ca$^{2+}$ (40 times) could be increased faster than in the reactors using the synthetic wastewater containing Fe$^{2+}$ ion (100 times) and control synthetic wastewater. The results of XMA analysis that a lot of the Ca$^{2+}$ ion on the surface of the anaerobic sludge in the anaerobic reactor packed by Ringlace which were fed supplied with synthetic wastewater containing Ca$^{2+}$ ion (40 times) observed as compared to the reactors supplied with control synthetic wastewater and containing Fe$^{2+}$ ion (100 times).

• Proceedings of the Korean Magnestics Society Conference
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• 2005.12a
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• pp.108-108
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• 2005

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.4
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• pp.42-51
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• 2010

The purpose of this study is to analyze the characteristics of environment-friendliness of Root Barrier materials based on comprehensive experiments on harmfulness of Root Barrier materials and fish toxicity of Oryzias latipes mortality to verify eco-toxicity of each method of construction and Root Barrier material, which are to be applied by taking eco-toxicity into account when building ecological flows in upper areas on natural and artificial grounds. As a result, the following conclusions have been reached in this study: 1. In regard of the harmfulness analyzed, each material showed a different result of analytical value in each lab tank. Compared to lab tank, pH (la), DO (lb), T-N (VI) and T-coli (la) were in the same grade, but COD, SS, T-P and F-coli were less than that of control, respectively increased or decreased by material were analyzed. 2. In the experiment of fish toxicity, Barrier sheet was found to have 66.7% of fish mortality, indicating strong fish toxicity. Synthetic rubber system root barrier sheet (20.0%) was analyzed to have medium fish toxicity, while Synthetic resin system root barrier-waterproof sheet (3.3%), Synthetic rubber system membrane root barrier sheet (3.3%) and Synthetic resin system root barrier sheet (0.0%) showed relatively lower mortality and fish toxicity. To sum up such results as found in the experiment mentioned so far, the values of harmfulness and root penetration resistance analyzed were different in each lab tank, but there was absolutely little correlation with the mortality gained from the experiment on fish toxicity. In the experiment of fish toxicity, environment-friendly root barrier materials were analyzed, and it was found that Synthetic resin system root barrier sheet, Synthetic resin system root barrier waterproof sheet and Synthetic rubber system membrane root barrier sheet are highly environment-friendly. In contrast, Synthetic rubber system root barrier sheet was found to have medium-level environment-friendliness. Also, Barrier sheet was analyzed to have low environment-friendliness.

• Journal of architectural history
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• v.15 no.1 s.45
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• pp.41-60
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• 2006

Preservation of wooden architecture by means of synthetic resin, is physical and chemical work. Synthetic resins are using for consolidation and restoration of decayed members. Since 1978, synthetic resin became useful preservation of architectural heritage in Korea. The first object was Chimgyeru of Songgwang-temple in Suncheon city. In the 1980s, have begun the care of materials for conservation on the architectural heritage, it was influenced according to authenticity of UNESCO Venice charter's principle, in 1964. In Korea, preservation of wooden architecture by means of synthetic resin that is sing many kinds of epoxies. Among the specific types of epoxies are araldite XN1023, SV427, etc. The use of synthetic resin have merits and demerits in the restoration for architectural heritage. The merit is that it is more smaller change with new members during preservation work. But the demerit is an irreversibility of the epoxy resin. In 1999, 'ICOMOS International Wood Committee' recommend contemporary materials and techniques, should be chosen and used with the greatest caution. And preservation work should reversible, as possible as technically. Therefore, should be data continous for preservation of wooden architecture by synthetic resin. Because data is very important work about a preservation of wooden architecture by synthetic resin. And should be try to think about new materials and techniques instead of synthetic resin, in the long view.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.489-494
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• 2013

An improved method for the preparation of monomethine cyanine dyes with quinoline nucleus by one-pot three-component using 1-methyl-2-quinolinethione, quaternized 2- or 4-methylheterocyclic compounds and methyl p-toluenesulfonate as starting materials was described. Compared with the traditional methods, the new synthetic method reduced the reaction steps, shortened the reaction time, avoided the separation and purification of the intermediate and reduced cost. The dyes absorbed in the region 478.0-563.0 nm and had molar extinction coefficients of $1.3{\times}10^4-9.4 {\times}10^4L\;mol^{-1}\;cm^{-1}$. Their fluorescence maxima and Stokes shifts were in the range of 525.2-594.4 nm and 16.2-80.6 nm in different solvents, respectively. From the spectral properties of the dyes in different solvents, it could be found that the ${\lambda}_{max}$ of the dyes were shorter in protonic solvents, and showed hypsochromic shifts with the increase of polarity of the solvents.

• Clean Technology
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• v.17 no.1
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• pp.1-12
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• 2011

Scientists and engineers have altered the properties of materials such as metals, alloys, polymers, ceramics, and so on, to suit the ever changing needs of our society. Man-made engineering materials generally demonstrate excellent mechanical properties, which often tar exceed those of natural materials. However, all such engineering materials lack the ability of self-healing, i.e. the ability to remove or neutralize microcracks without intentional human interaction. The damage management paradigm observed in nature can be reproduced successfully in man-made engineering materials, provided the intrinsic character of the various types of engineering materials is taken into account. Various self-healing ptotocols that can be applied for the organic materials such as polymers, ionomers and composites can be developed by utilizing suitable chemical reactions and physical intermolecular interactions.

• Elastomers and Composites
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• v.44 no.3
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• pp.196-208
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• 2009

Sophisticated polymeric materials with 'responsive' properties are beginning to reach the market. The use of reversible, noncovalent interactions is a recurring design principle for responsive materials. Recently developed hydrogen-bonding units allow this design principle to be taken to its extreme. Supramolecular polymers, where hydrogen bonds are the only force keeping the monomers together, form materials whose (mechanical) properties respond strongly to a change in temperature or solvent. In this review, we describe some examples of hydrogen-bonded supramolecular polymers that can be utilized for self-healing materials. Synthesis of a rubber-like material that can be recycled might not seem exciting. But one that can also repeatedly repair itself at room temperature, without adhesives, really stretches the imagination. Autonomic healing materials respond without external intervention to environmental stimuli in a nonlinear and productive fashion, and have great potential for advanced engineering systems.