• Journal of the Korean Chemical Society
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• v.16 no.4
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• pp.205-207
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• 1972

Dodecylquinolinium bromide has been synthesized and the critical micelle concentrations of it in the aqueous solution have been determined by the measurement of the surface tension and the electrical conductance. The values are $3.34 {\times} 10^{-3}mole/l$ and 3.41 {\times} $10^{-3}$mole/l, respectively. Since dodecylquinolinium bromide has the larger hydrophobic group than dodecylpyridinium bromide, it is considered that the former has the smaller critical micelle concentration than the latter.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.699-706
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• 1991

The moderate power (500 W) Microwave Induced Plasma was generated with helium gas and was used for the direct analysis of aqueous samples. Usually, the helium plasma obtained with a modified Beenakker type cavity forms a cylindrical one. Though, by the careful controls of gas flows, a "toroidal" shape plasma could be made but its analytical performances were found to be worse. Using the glass frit nebuliser, the detection limits for metal ions obtained were around 10~100 ppb and that for chloride was about 50ppm.

• Journal of the Korean Chemical Society
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• v.35 no.2
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• pp.105-110
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• 1991

The dissociation constants of valine and norvaline in aqueous solution were measured by conductometric method in various temperatures and pressures. The properties of the dissociation reaction were discussed in term of the thermodynamic properties of reaction. These substituted effects on the dissociation reaction were discussed on the points of Hammett relation and net charge of the O and N-atom calculated from CNDO/2 method respectively.

• Journal of the Korean Vacuum Society
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• v.3 no.3
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• pp.264-268
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• 1994

본연구에서는 HCl 또는 NH4OH로 산화막을 식각학 GaAs 표면에 H2S 가스를 이용하여 유황처 리하였다. 표면의 화학적 조성 및 결합상태를 측정하기 위하여 AES 및 XPS를 사용하였다. 시편들은 30,200 및 $350^{\circ}C$로 가열하면서 H2S가스와 반응시켰다. 이때 유황은 GaAs 표면의 Ga 원자 및 As 원자 와 화학결합을 형성하고 있음이 밝혀졌다. 또한 $350^{\circ}C$로 가열된 시편이 $30^{\circ}C$ 또는 $200^{\circ}C$로 가열된 시편 보다 표면에 결합된 유황의 양이 많은 것으로 나타났다. 아울러 (NH4)2S 수용액 또는 Na2S 수용액으로 유황처리된 경우와 동일하게 H2S 가스로 유황처리된 GaAs 표면에서는 Ga 산화막 및 As 산화막이 거 의 관측되지 않았다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.147-148
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• 2018

In order to compare the electrochemical performance with that of Calomel Electrode, MnO2 solid-state-electrode was fabricated and its potential and impedance were measured in chloride aqueous solution. As a result, the SCPS without chloride ions showed a potential of -200 mV or more and an impedance over 2000 Ωcm, but the potential below -600 mV and the impedance below -200 Ωcm showed as the chloride concentration in the solution increased. It is considered electrochemical studies on the corrosion of rebar are necessary for the MOE, which shows the same tendency as SCE and exhibits electrochemical performance, over the Mortar level in the future.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.243-248
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• 1988

The hypersensitive $f{\rightarrow}f$ transitions of Nd(III), Ho(III), and Er(III) have been studied for some lanthanide complexes in aqueous solution. Based on the linear correlation between the oscillator strength of the transition and the basicity$(pK_a)$ of the ligand, the covalency in the metal-ligand bonding is discussed for lanthanide anthranilate, pyrazine-2-carboxylate, and pyruvate.

• Journal of the Korean Chemical Society
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• v.63 no.4
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• pp.289-306
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• 2019

The purpose of this study is to compare the contents of chemistry textbooks developed according to the 2015 revised curriculum with the contents of the 2009 revised curriculum to research the change in "the development and use of models". To do this, we analyzed 8 kinds of Chemistry I textbooks and 6 kinds of Chemistry II textbooks from the 2015 revised curriculum and compared them with 4 kinds of Chemistry I textbooks and 4 kinds of Chemistry II textbooks from the 2009 revised curriculum. The scope of the analysis was the explanations of the textbooks related to aqueous electrolysis experiments. In order to compare the contents regarding electrolytes when the same experiments are interpreted with different models, we analyzed contents of 4 kinds of middle school science textbooks from the 2015 revised curriculum and 9 kinds of middle school science textbooks from the 2009 revised curriculum. As a result of the analysis, the same experiment was explained by different models according to the grade level and unit, and all explanations were limited to a single model. Also, the tendency to limit the kinds of electrolytes for controlled experimental results is more pronounced in the 2015 revised curriculum than in the 2009 revised curriculum. From this results, we suggest that efforts are needed to reflect the "development and use of models" in chemistry textbooks developed according to the 2015 revised curriculum.

• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.28-32
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• 1992

The critical micelle concentration(CMC) values of Dodecylpyridinium bromide(DoPB) were determined by an electric conductivity method at 1${\sim}$2000 bars and $25^{\circ}C$. The CMC of DoPB increases with the addition of urea in the whole pressure region studied, and the CMC increases with an increase of the pressure in the low-pressure region, while in the high-pressure region the CMC decreases. The partial molar volume change $({\Delta}V^m_o)$ on micellization was also investigated in some urea aqueous solutions. The change $({\Delta}V^m_o)$ was reduced by the addition of urea. The results suggest that the "iceberg" structure of water around the hydrocarbon chain of the monomeric surfactant is effectively broken down by urea.

• Resources Recycling
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• v.24 no.4
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• pp.50-55
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• 2015

In this study, we have investigated solvent extraction of Ga and recovery of high pure Ga solution from MOCVD dust for manufacturing of LED chip. Effect of extractan, concentration of extractant were examined for choosing the more effective extractant and high pure Ga solution was fabricated by multi-stage extraction/stripping process. For extraction/separation of Ga based on the analysis of raw-material in previous study, 3 different extractants PC 99A, DP-8R, Cyanex 272 has been investigated and the extraction efficiency of 1.5 M Cyanex 272 was 43.8%. It was conformed that extraction efficiency of Ga was 83% in multi-stage extraction and 5N high purity Ga stripping solution without impurities also obtained.

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.163-168
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• 2011

The variations of molar conductivity of various surfactants such as sodium caprylate, sodium laurate, sodium palmitate, sodium stearate, sodium oleate, sodium dodecyl sulphate, and lithium dodecyl sulphate with concentrations of the surfactants for each of the solutions consisting of mixtures of varying concentrations of N-methyl acetamide in water at constant temperature of $30{\pm}0.2^{\circ}C$ were studied. The critical micelle concentration (CMC) for each surfactant is measured. It is found that the CMC values in mixtures of N-methyl acetamide and water solutions of various surfactants are lower than the CMC values in water, and the driving force for micelle formation correlates with solvophobicity. The surfactant-solvent interactions that drive amphiphilic self-organization in N-methyl acetamide in water are discussed. Thermodynamic parameters were evaluated for micellar system to explain the results.