• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.323-327
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• 2005

Pentachlorophenol (PCP) is a representative compound of chlorophenol derivatives which are especially toxic and potentially carcinogenic compounds in the priority pollutant list of the EPA (Environmental Protection Agency, USA). The aim of this study was to investigate an analysis method of PCP in infinitesimal quantity retained in paper. PCP in paper was pretreated by solid phase extraction (SPE) in a phenyl cartridge. The extracted sample was acetylated or silylated and analyzed with GC/MS-SIM. The detection sensitivity of silylated PCP was improved significantly when compared with those of PCP itself and acetylated PCP. As a test specimen, an office paper and a wallpaper were used.

• Analytical Science and Technology
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• v.14 no.5
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• pp.384-391
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• 2001

In this study, a new quantitative analytical method has been developed for the rapid determination of acylcarnitines and amino acids in human blood using electrospray ionization / tandem mass spectrometry (ESI-MS/MS). Acylarmitines and amino acids were analyzed by tandem mass spectrometry after conversion to their butylesters through treatment with 3N butanolic hydrogen chloride. Acylcrnitines were analyzed using precursor 85 ion scan and alanine, valine, leucine/isoleucine, methionine, phenylalanine, tyrosine, aspartic acid and glutamic acid were analyzed using neutral loss 102 scan, ornitine and citrulline were analyzed neutral loss 119 scan, glycine was analyzed using neutral loss 56 scan, arginine was analyzed using neutral loss 161 scan and argininosuccinic acid was analyzed product ion 459 scan. This method reduced sample preparation time compared to that with conventional amino acid analyzer and liquid chromatography, with high sensitivity and good reproducibility.

• The Journal of the Korea Contents Association
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• v.18 no.8
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• pp.92-101
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• 2018

As the interactive AI speaker becomes popular, voice recognition is regarded as an important vehicle-driver interaction method in case of autonomous driving situation. The purpose of this study is to confirm whether multimodal interaction in which feedback is transmitted by auditory and visual mode of AI characters on screen is more effective in user experience optimization than auditory mode only. We performed the interaction tasks for the music selection and adjustment through the AI speaker while driving to the experiment participant and measured the information and system quality, presence, the perceived usefulness and ease of use, and the continuance intention. As a result of analysis, the multimodal effect of visual characters was not shown in most user experience factors, and the effect was not shown in the intention of continuous use. Rather, it was found that auditory single mode was more effective than multimodal in information quality factor. In the semi-autonomous driving stage, which requires driver 's cognitive effort, multimodal interaction is not effective in optimizing user experience as compared to single mode interaction.

• Journal of Labour Economics
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• v.26 no.3
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• pp.115-147
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• 2003

This paper scrutinizes the robustness of the profit-sharing findings first employing an original panel data on the Employee Welfare Fund over the period from 1992 to 2000. In examining the effects of profit-sharing schemes on labor productivity, it controls for simultaneity among profit-sharing, production factors, and productivity using both the two-stage least squares procedure and the lagged variable method. The empirical results show that an increase in firm's contribution to the Employee Welfare Fund is associated with capital-embodied and disembodied productivity enhancement, which is both statistically and economically highly significant. The empirical results are in contrast with predictions of both agency and transaction cost theories, and they imply that more tax benefits and financial incentives for expansion of the Employee Welfare Fund should be required to get productivity gains.

• Polymer(Korea)
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• v.31 no.6
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• pp.474-478
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• 2007

Polymer substrate materials with low dielectric loss were obtained by fabricating the composite using dicyclopentadienyl bisphenol cyanate ester oligomer and polyphenylene ether (PPE). From the analysis of the curing reaction of oligomer and catalyst, it was observed that the optimum amount of catalyst was 0.02 phr of Zn content. It was applied to the fabrication of polymer composite. By changing oligomer/PPE weight ratio, the peel strength and the gel content of the fabricated composites were measured, and then, the dielectric constant and the dissipation factor were measured in the GHz frequency range. The amount of PPE affected the peel strength and the dielectric properties of composites. However, the amount of catalyst did not affect them at all. Resulting from all experiments, we obtained polymer composite laminates haying the peel strength of above 1 kN/m and the low dissipation factor of 0.004 at 1 GHz.

• Polymer(Korea)
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• v.34 no.1
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• pp.69-73
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• 2010

Effects of reaction time and temperature on the isomerization and dehydrobromination reactions of brominated butyl rubber were investigated. The structural composition of brominated butyl rubber was determined by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy($^1H$-NMR), Density functional theory (DFT) was used to study on the isomerization and dehydrobromination mechanisms of model compounds. The geometries for model compounds of 3-bromo-5,5,7,7-tetramethyl-2(2',2',4',4'-tetramethyl)pentyl-1-octylene (3BrOE), 1-bromo-5,5,7,7-tetramethyl-2(2',2',4',4'-tetramethyl)pentyl-2-octylene (1Br2OE) and 5,5,7,7-tetramethyl-2(2',2', 4',4'-tetramethyl)pentyl-1,3-octadiene (CD) had been optimized by using density functional theory at B3LYP/3-21G and B3LYP/6-31G levels. The predicted energy of 3BrOE lies higher than that of 1Br2OE which suggests that 1Br2OE configuration is more stable than the 3BrOE configuration. Compared with the energy barrier, the pathway of dehydrobromination is less competitive than that of isomerization. This is qualitatively consistent with the experimental results.

• Journal of the Korean Chemical Society
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• v.35 no.2
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• pp.158-164
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• 1991

The reduction mechanism at a mercury electrode of o-cresolphthalexon(OCP) in strongly alkaline supporting electrolytes has been investigated by several electrochemical techniques. The radical formed after first one electron reduction uptake, dimerizes. The result of cyclic voltammetric investigation demonstrated the reversible nature of the electron transfer and standard rate constant was $3.27{\times}10^{-2}$ cm/sec. The apparent irreversible behavior of the second wave is a result of the existence of a fast protonation following the second electron transfer. At low concentration of OCP(< $1{\times}10^{-4}$M), cathodic current were remarkably adsorptive properties. Prolonged electrolysis was carried out at controlled potential of -1.85V, original violet color of the solution becames progressively weaker, and then colorless solution. The final product of an exhaustive electrolysis is electro-inactive. The appearence of four steps may be explained by the fact that the reduction of OCP elucidated ECEC mechanism.

• Journal of the Korean Society for Heat Treatment
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• v.28 no.5
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• pp.229-238
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• 2015

The effects of Sn addition and solution treatment on corrosion behavior were studied in AZ91 magnesium casting alloy. The addition of 5%Sn contributed to the introduction of $Mg_2Sn$ phase, to the reduction in dendritic cell size and to the increase in the amount of secondary phases. After the solution treatment, trace amount of $Al_8Mn_5$ particles were observed in the ${\alpha}$-(Mg) matrix for the AZ91 alloy, while $Mg_2Sn$ phase with high thermal stability was additionally found in the AZ91-5%Sn alloy. Before the solution treatment, the AZ91-5%Sn alloy had better corrosion resistance than the Sn-free alloy, which is caused by the enhanced barrier effect of the (${\beta}+Mg_2Sn$) phases formed more continuously along the dendritic cell boundaries. It is interesting to note that after the solution treatment, the corrosion rate of both alloys became increased, but the Sn-added alloy showed higher corrosion rate than the Sn-free alloy. The microstructural examination on the corroded surfaces revealed that the remaining $Mg_2Sn$ particles in the solution-treated AZ91-5%Sn alloy play a role in accelerating corrosion by galvanic coupling with the ${\alpha}$-(Mg) matrix.

• Korean journal of communication and information
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• v.84
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• pp.28-98
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• 2017

This work critically deals with the much unstable and fragmented states of young adults in contemporary Korean society. Nowadays, most of young adults in Korea have encountered much severe, uncertain, and 'hellish' socio-economic situations while their dreams of getting regular jobs are hard to achieve. This study aims to present a nuanced and detailed analysis of their sedimented feelings, variegated emotions, as well as embodied positions by utilizing in-depth interviews and critical explorations on their particular modes of survival.

• Journal of The Korean Association For Science Education
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• v.30 no.2
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• pp.218-233
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• 2010

The purpose of this study was to explore science teacher's epistemological understanding of science and science teaching and learning, from the perspective of inquiry as the process of scientific knowledge building. Three science teachers participated in this study. The data were collected from individual in-depth interviews and classroom videotaping. The results show a case involving coherent and consistent data. It showed that the teacher's epistemological understanding of science and science teaching and learning consisted of five categories: scientists doing science with scientific thinking; scientific thinking as the process of knowing; science learner in the learning process of scientific thinking; science teacher as a man/woman with good understandings of science; and teaching and learning as the process of knowing science. Based on the results, discussions and implications about science education and science teacher education were presented.