• Journal of the Korean Chemical Society
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• v.40 no.4
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• pp.229-234
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• 1996

Carcinogenicities of Benzo[a]pyrene(BP) and its metabolites were investigated by PM3. The 4, 5, 5a, and 6 positions forming transbutadiene(TB) frame in BP have been proved to be carcinogenic region by LUMO. We have found that the carcinogenic region of BP-triol, ultimate cacinogen, is shifted from 4, 5, 5a, and 6 positions of precarcinogen to 10, 10a, 12c, and 12b ones. The appreximate charge transfer quantities turned out to have the largest value between HOMO of Guanine and LUMO of BP-triol corresponding to TB region on each other.

• Journal of the Korean Chemical Society
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• v.43 no.3
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• pp.321-327
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• 1999

The STS materials, emphasized in the 6th curriculum, in the chemistry part of middle school science textbooks were analyzed. The average value of the STS content of textbook was 13.2%. In the study of chapter of textbook, 15.9% of STS materials was included in the chapter of ？reaction of materials?, 12% in "character and separation of materials", and 10.8% in "composition of materials". When the STS topics classified by Piel were analyzed, the results were as follows; 40.2% on sociology of science, 28.8% on environmental quality and utilization of natural source, 20.4% on effects of technological developments, and 12.9% on energy. However, the topic on human engineering was only included in a textbook, and the topics on space research and national defence were not included in any textbooks. When the STS materials were analyzed by student activities of SATIS, the number of activities was 71. Most activities were consisted of solving problems and decision, simulation and data analysis, and there was no research design and role playing.

• Journal of the Korean Chemical Society
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• v.66 no.2
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• pp.136-149
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• 2022

Chemistry focuses on explaining macroscopic phenomena at the microscopic level with particles, such as atoms or molecules. Explanation using particles are bound to be considered as abstract by students, because it was dealing with invisible objects. For that reason, the science national curriculum presented to middle school students the explanation of the units related to the composition of matter. Therefore, understanding about the composition of matter in middle school students becomes an important basis for learning of chemistry, and it is necessary to investigate their understanding about composition of matter. In this study, students' understanding about 'composition of matter' region, which is first presented to middle school students, was confirmed at an overall level. In this line, this study analyzed the results of the items in the composition of matter region, and analyzed items were used in the National Assessment of Educational Achievement (NAEA) from 2015 to 2019. We analyzed the 9 items presented in the NAEA according to the response rate of options and response rate distribution curve, and explained the characteristics of understanding derived by each achievement level were examined. According to the analyzed results by dividing the conceptions about elements, atoms, and ions, students above the proficient achievement-level had scientific conceptions overall, but students below the basic achievement-level had inconsistent or naive conceptions. Based on the results for each item, this study discussed some implications to be considered or to be improved on teaching-learning for 'composition of matter'.

• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.215-224
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• 1987

The electrical conductuctivity measurements have been made on polycrystalline samples of various compositions in the $MgO-TiO_2$ system from 600 to $1100^{\circ}C$ under $Po_2$'s of $10^{-8}\;to\;10^{-1}$atm. Plots of log ${\sigma}$ vs. 1/T at constant $Po_2$ are found to be linear with the inflections, and the activation energies are 1.94eV for the intrinsic range and 0.48eV for the extrinsic range, respectively. The log ${\sigma}$ vs. log $Po_2$ curves are found to be linear at constant temperature, and the conductivity dependences of $Po_2$ are closely approximated by ${\sigma}\;{\alpha}\;Po_2^{-1/6}$ for the extrinsic and ${\sigma}\;{\alpha}\;Po_2^{-1/4}$ for the intrinsic range, respectively. The dominant defects in this system are believed to be oxygen vacancy for the extrinsic and $Ti^{3-}$ interstitial for the intrinsic range. The conduction mechanisms in both the extrinsic and the intrinsic ranges are proposed by the results of the electrical conductivity dependence on the oxygen partial pressure. Polaron model was suggested in the extrinsic region by the conductivity dependences of temperature and $Po_2$.

• Journal of The Korean Association For Science Education
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• v.22 no.2
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• pp.378-386
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• 2002

In this study, the students' responses on the chemistry items of in the general science of College Scholastics Ability Test (CSAT) implemented for the past 3 years since 1999 were investigated. The number of items by content and inquiry process, the average percent correct by content and inquiry process, the distribution of items by the level of percent correct, and the items with high and/or low percent correct were analysed. There were the fewest items in 'environment' area, especially in 'ozon layer', no test item had been made. The most difficult content area was 'acid rain' in 'environment'. By inquiry process, the most number of items belonged to 'analyzing & interpreting data', and 'identifying problems & formulating hypothesis' was the most difficult process. No test item came under the level of 'very difficult', and many items under the 'easy' or 'very easy' level. Students were generally poor at solving test items demanding several concepts, and very good at simply requiring basic concept treated in lower grade. Educational implications are discussed.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.397-398
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• 2003

대기 중 분진을 제거하는 방식으로 여과 이론을 적용할 수 있는 경우는 섬유 여과기, 입자상 여과기, 액적에 의한 습식 세정기 그리고 기포를 이용한 분진 제거 방법 등을 들 수 있다. 이러한 여과 원리를 이용한 집진 설비를 설계하는데 있어, 액적 또는 기포 주위의 유동장을 정확히 파악하는 것은 매우 중요하다. 특히, 포집구의 크기가 작아지고 화학적으로 반응성을 갖는 고온의 함진가스가 유입되는 경우 및 저압에서 운영되는 경우에 누드센수(Knudsen number)의 영향을 무시할 수 없는데 이러한 영역을 저 누드센 영역(low Kundsen number regime)이라고 한다(Lee et al., 1978). (중략)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.127-131
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• 1998

The effect of extraction temperature ($60\~100^{\circ}C$) and pH ($2.0\~13.5$) on the yield and chemical compositions of crude porphyran from Porphyra Yezoensis was investigated. The yield and chemical compositions of crude porphyran were greatly affected by extraction pH and temperature. Yield was highest between pH $3\~4$ at all temperature ranges. Crude porphyran extracted in acidic conditions showed more sulfate and less protein content than extracted in neutral conditions, but molecular weights was decreased. Crude porphyran extracted in alkaline conditions showed low sulfate and high protein content. For high yield and low molecular weight, acidic condition, particulary pH $3\~4$, was effective. But in order to avoid molecular weight degradation, neutral conditions were effective.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.5
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• pp.937-942
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• 2001

The present study was conducted to identify the mechanism about the regulation of appetite by examining the expression patterns of vasoactive intestinal peptide in the hypothalamus of either fasted for 24 hours or anorexia mutant mouse. In order to investigate expression pattern of the vasoactive intestinal peptide, immunohisto-chemistry was employed along with reverse transcription polymerase chain reaction (RT-PCR) and dot blotting. Immunohistochemistry has shown that level of expression of vasoactive intestinal peptide and appetite-suppessing neuropeptide, was lower in the suprachiasmatic nucleus (SCN) and higher in the paraventricular nucleus (PVN) of the anorexia mutant group than in the comparable regions in the control group. This pattern was repeated in the fasting group, which also showed lower and higher levels of vasoactive intestinal peptide expression in the SCN and PVN respectively, In contrast, the vasoactive intestinal peptide mRNA level in the entire hypothalamus via RT-PCR and dot blotting was similar in the fasting and control groups, while it was significantly increased in the anorexia mutant group.

• Journal of the Korean Chemical Society
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• v.54 no.3
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• pp.329-337
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• 2010

In this study, we analyzed the end-of-chapter questions in 8 types of chemistry II textbooks for science teachers according to revised Bloom's taxonomy of educational objectives not only to raise interests of questions in textbooks but also acquire a basic material for using questions in textbooks effectively. The results of classification following Bloom's cognitive category showed that 'Understanding(44.7%)' level was the most, then 'Application(29.9%)', Knowledge(15.6%) and 'Analysis (9.5%)' in order, which is distinct difference from the result of classification of the end-of-chapter questions in college general chemistry books which was 'Application', 'Analysis' and 'Understanding' in order. Especially, questions of 'Evaluation' level were not found at all in any textbook investigated and 'Synthesis(0.3%)' level was very few. On the other hand, the percentage of questions in 'Understanding' and 'Executing Quantitative' which required specific algorithms was 70% of total with most of the questions in 'Application' were 'Executing Quantitative'.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.857-874
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• 2011

The purposes of this study were to develop teaching strategy enhancing creative problem solving skills and to examine the instructional influences on studints' creative thinking skills, critical thinking skills, creative personality and academic self-regulation. In this study, a model using inter-disciplinary analogies(PDCA model) was designed and applied to the existing 'Teaching model for the enhancement of the creative problem solving skills'. And it was implemented to preservice science teachers for the one semester. Results indicated that the experimental group presented statistically meaningful improvement in creative thinking skills, especially in the originality of identifying a problem, making hypothesis, and controlling variables (p<.05). In addition, the strategy contributed to improving critical thinking skills, especially in inquiry process of recognizing problems, making hypothesis, interpreting and transforming of data (p<.05). This strategy also helped students' academic self-regulation (p<.05). But there was no significant improvement in creative personality(p<.05).