• Journal of the Korean Chemical Society
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• v.63 no.6
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• pp.459-472
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• 2019

The purpose of this study was to investigate the effect of science writing for different audiences on preservice chemistry teachers' chemistry concept understanding and modeling ability in general chemistry experiment activities using Argument-based Modeling (AbM) strategy. And we also examined preservice chemistry teachers' perceptions of modeling in different audience groups. The participants of the study were 18 university students in the first grade of preservice chemistry teachers taking a general chemistry experiment course. They completed eleven topics of general chemistry experiment using argument-based modeling strategy. The understanding of chemistry concept was compared with the effect size of pre- and post-chemistry concept test scores. To find out modeling ability, we analyzed level of model by each preservice chemistry teacher. Analytical framework for the modeling ability was composed of three elements, explanation, representation, and communication. The questionnaire was conducted to check up on preservice chemistry teacher's recognition of modeling. The result of analyzing the effect of modeling for different audience on the understanding of chemistry concept and modeling ability, the preservice chemistry teachers' were found to be more effective when the level of audience was low. There was no difference in the recognition of modeling between the groups for audience. However, we could confirm that the responses of preservice chemistry teachers are changed in concrete when they have an experience in succession on modeling.

• Bulletin of the Korean Chemical Society
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• v.14 no.3
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• pp.363-366
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• 1993

• Journal of the Korean Chemical Society
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• v.46 no.6
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• pp.550-560
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• 2002

This study was to explore students' thought patterns on problem and problem solving in the course of general chemistry. The participants were 9 students taking the course of general chemistry in a university in Seoul. Data were collected from various sources; three individual interviews, classroom observations, and essays written by students.Data were all transcribed and then analyzed circularly in constant component analysis. As the results of this study, six thought patterns of students in the context of learning general chemistry were presented. These thought patterns were common and existed important component within most of students' conceptual ecologies about learning chemistry. Implications of chemistry and science learning related to this results were discussed.

• Bulletin of the Korean Chemical Society
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• v.27 no.12
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• pp.1961-1962
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• 2006

• Rapid Communication in Photoscience
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• v.1 no.2
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• pp.61-61
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• 2012

• Journal of the Korean Chemical Society
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• v.60 no.4
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• pp.276-285
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• 2016

This study aimed to examine preservice science teachers' modeling ability and how it has changed in argument-based chemistry laboratory investigations. The participants for this study were twenty-one freshman students from teachers’ college and they carried out six topics of argument-based chemistry laboratory investigation. Students’ written modeling samples were collected and analyzed to investigate preservice science teacher's modeling ability and changes in it. The results of this study showed that preservice science teacher's modeling ability has improved and progressed through argument-based chemistry laboratory investigations.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2377-2381
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• 2007

Solvolyses of 3,4-dimethoxybenzenesulfonyl chloride (DSC) in water, D2O, CH3OD, and in aqueous binary mixtures of acetone, acetonitrile, 1,4-dioxane, ethanol, methanol, and 2,2,2-trifluoroethanol (TFE) have been investigated at 25.0 oC. Kinetic solvent isotope effects (KSIE) in water and in methanol and product selectivities in alcohol-water mixtures are also reported. The Grunwald-Winstein plot of first-order rate constants for the solvolyic reaction of DSC with YCl shows marked dispersions into separated lines for various aqueous mixtures. With use of the extended Grunwald-Winstein equation, the l and m values obtained are 1.12 and 0.58 respectively for the solvolyses of DSC. The relatively large magnitude of l is consistent with substantial nucleophilic solvent assistance. From Grunwald-Winstein plots the rate data are dissected approximately into contributions from two competing reaction channels. This interpretation is supported for alcohol-water mixtures by the trends of product selectivities, which show a maximum for ethanol-water mixtures. From the KSIE of 1.45 in methanol, it is proposed that the reaction channel favored in methanolwater mixtures and in all less polar media is general-base catalysed and/or is possibly (but less likely) an addition-elimination pathway. Also, the KISE value of 1.35 for DSC in water is expected for SN2-SN1 processes, with minimal general base catalysis, and this mechanism is proposed for solvolyses in the most polar media.

• Journal of the Korean Chemical Society
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• v.53 no.1
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• pp.62-72
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• 2009

In this study, entropy definition and explanation in twelve general chemistry textbooks published in USA including what Korean universities select are analyzed. Analysis consists of two parts. One is diachronic analysis which focuses on the change between editions of same authors and the other is contents analysis composed of three sections‐ disorder in entropy definition and explanation, microstates number in entropy definition and explanation, possibility of alternative conception in learning statistical entropy and thermal entropy. As a result, the definition that entropy is the measure of disorder is denied and explanation using microstates number is introduced. Also, caution for the possibility of alternative conception that there are two different entropies is found. Reflecting the change in entropy explanation on new chemistry curriculum and reeducating teachers are meaningful on improvement of Korean chemistry education.

• Bulletin of the Korean Chemical Society
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• v.9 no.1
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• pp.36-40
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• 1988

The time correlation functions of concentration fluctuations due to the random forces near the steady state are evaluated for a general two-component nonlinear chemical system by solving the corresponding two dimensional Fokker-Planck equation. The approximate method of solving the Fokker-Planck equation is based on the eigenfunction expansion and the corresponding eigenvalues for both the linear and nonlinear Fokker-Planck operators are obtained near the steady state. The general results are applied to the Lotka model near the oscillatory marginal steady state and the comparison is made between linear and nonlinear cases.

• BMB Reports
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• v.28 no.3
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• pp.204-209
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• 1995

The pH dependence of kinetic parameters in the amination direction of the aspartase from Hafnia alvei has been determined. The V/K for fumarate is bell shaped with pK values of 6.4 and 8.7. The maximum velocity for fumarate is also bell shaped with pK values of 7.2 and 9.1. The pH dependence of 1/K, for potassium (competitive inhibitor of ammonia) decreases at low pH with pK 7.6. Together with data [Yoon and Cook (1994) Korean J. Biochem. 27, 1-5] on the deamination direction of the aspartase, these results are consistent with two enzyme groups which are necessary for catalysis. An enzymatic group that must be deprotonated has been identified. Another enzyme group must be protonated for substrate binding. Both the general base and general acid group are in a protonation state opposite that in which they started when aspartate was bound. A proton is abstracted from C-3 of the monoanionic form of L-aspartate by an enzyme general base with, a pK of 6.3~6.6 in the absence and presence of $Mg^{2+}$ Ammonia is then expelled with the assistance of a general acid group giving $NH_{4+}$ as the product.