• Journal of the Korean Chemical Society
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• v.47 no.2
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• pp.155-164
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• 2003

This study examined the types of explanations related to physical change and chemical change in the science textbooks of middle and high school based on the prior study of science teachers' understanding. For this research, the researchers analyzed 44 textbooks of middle school science and high school chemistry. As a result, there were no explanation or property type explanation represented in most of the textbooks related to physical and chemical change concepts. Also, there are few relationship represented between physical change and chemical change, and the examples related to physical change and chemical change were confused. These representations of textbooks can give rise to confusion of understanding of teachers and learners. So, it needs to re-design the explanation types correctly and constantly in science textbooks related to physical change and chemical change.

• Journal of the Korean Chemical Society
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• v.65 no.2
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• pp.145-150
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• 2021

The present study describes a hands-on experiment to help students understand the concept of phase change or phase transition and its application in a phase change material (PCM). PCMs are substances that have the capability of storing and releasing large amounts of thermal energy. They act as energy storage materials that provide an effective way to save energy by reducing the electricity required for heating and cooling. Lauric acid (LA) was selected as an example of the PCM. Students investigated the temperature change of LA and the temperature (of air) inside the test tube. The differences in the temperatures of the systems helped students understand how PCMs work. A one-group pretest and posttest design was implemented with 34 grade-11 students in science and mathematics. Students' understanding was assessed using a multiple-choice test and a questionnaire. The findings revealed that the designed activity helped students understand the concept of phase change and its application to materials for thermal energy storage.

• Journal of the Korean Chemical Society
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• v.23 no.1
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• pp.15-19
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• 1979

The new concept of the Bonding and Antibonding Regions in the transition density space is developed from the Integral Hellmann-Feynman Theorem and the positive definiteness of the transition density. The unility of this concept is fully demonstrated for H2 system. It is expected that the nature of the electronic perturbation energy due to the change of nuclear configuration can be successfully understood by using this concept. Properties of the transition density is briefly discussed.

• Journal of the Korean Chemical Society
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• v.43 no.2
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• pp.213-224
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• 1999

Preconceptions of middle school students related to chemical change the students are surveyed. The students are divided into experimental group that are learned by concept change theory teaching model, and control group that are learned by traditional teaching method based on science textbooks. After the planned classes, the tendencies of concept change of the two groups according to students learning motivations are analyzed. New teaching methods, which based on concept change learning model and students learning motivations, developed by this research. And the effects of the new teaching method are testified. As a result, it is proved that most of the students have a lot of preconceptions, and persist the wrong conceptions after the classes. This tendency is same in the control group and in the experimental group.

• Journal of The Korean Association For Science Education
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• v.19 no.1
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• pp.91-99
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• 1999

The researches related to students' preconceptions and conceptual change model have been reported that students' learning motivation is one of the key variable for the conceptual change. The effects of students learning motivations on conceptual changes were evaluated. Subjects of this study were 8th grade students. and they were divided into 2 groups. One group was taught by traditional teaching method, and the other group by concept change teaching model. After the intervention, learning motivations of the students were testified. The students of high motivation who were taught by concept change teaching model showed higher scores in the concept of chemical change than the students by traditional teaching method. But there was no difference in both groups of students who have low learning motivations. The learning motivations before the intervention. the motivations stimulated by classes. and the degree of concept understanding showed high correlation. The motivations stimulated by classes explain 23.3 % of the degree of concept understanding. The results seems to mean that students learning motivations contribute to the understanding of concepts. Especially confidence of learning as a subcategory of the learning motivation contributes significantly to the understanding of new concepts. In contrast, the traditional teaching methods and the teaching methods of concept change learning theory were not effective for the stimulation of students learning motivations.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.191-194
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• 2004

A novel type of intelligent microcapsule reactor system was prepared. The reactor can recognize pH change in the medea and control reaction rate by itself. For the reactor system, acrylic acid (AA), N-isopropylacrylamide (NIPAM), and glucose oxidase (GOD) were selected as a pH-responsive device, a gating device according and a reaction device, respectively. Poly(NIPAM-co-AA) (P-NIPAM-co-AA) are known to change its hydrophilicity-hydrophobicity due to pH change. They were integrated in a core-shell microcapsule space. GOD was loaded inside the core space and the pores in the outside shell layer were filled with P-NIPAM-co-AA linear grafted chains as pH-responsive gates by plasma graft filling polymerization method. When P-NIPAM-co-AA gates are hydrophilic at high pH value, this microcapsule permits glucose penetration into the core space and GOD reaction proceeds. However, when P-NIPAM-co-AA gates are hydrophobic at low pH value, this microcapsule forbids glucose penetration and GOD reaction will not occur. The accuracy of this concept was examined.

• Environmental and Resource Economics Review
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• v.12 no.1
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• pp.91-120
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• 2003

This paper is intended to measure sectoral sustainabilities and inter-industry linkage effects of natural capital depletion of the Korean industries, and to analyze sources of their change over time using the familiar input-output model. The sustainability indicator that we are measuring in this paper is based on the so-called genuine saving concept proposed by the World Bank(1997). We accommodated the concept in the extended analytical framework of Proops et al.(1999) to analyze sectoral sustainabilities of the Korean industries. We decomposed sectoral sustainabilities so measured into their composing factors based on the decomposition method devised by Chung & Rhee (2001). According to our analysis, overall sustainability of the Korean industries has been declined since 1995. In heavy and chemical, transportation, and electricity sectors, their sustainabilities has been gotten worse. Among four major factors influencing the sustainability, change in GDP was the most important followed by changes in savings, industrial structures, and demand patterns.

• Journal of the Korean Chemical Society
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• v.64 no.1
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• pp.30-37
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• 2020

The purpose of this study was to identify the problems faced by students in sub-microscopic representation of acid-base reactions. Herein, we selected 30 students of 12^th grade science classes, who had studied various acid-base models. In order to investigate the sub-microscopic representation ability of the students, we developed nine items related to various contexts, such as one type of solute and solvent, two types of solutes and solvent, cases with water as solvent or with nonaqueous solvents. For all items, we consistently observed lack of concept of chemical change. In context of aqueous and nonaqueous solutions, the frequency of lack of concept of chemical bonding was high if ammonia was the solute or solvent. Moreover, the frequency of lack of concept related to the degree of electrolytic dissociation was high. Therefore, chemistry teachers should understand that students' ability to sub-microscopic representation of acid-base reactions can be enhanced by analyzing the difficulties faced by the students in solving diverse acid-base problems.

• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.65-72
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• 2007

The purpose of this study was to examine the 7th national science curriculum (chemistry domain) regarding the meanings of ‘mulgil' (Korean), the particulate nature of matter, and the state of matter. It was found that the term of ‘mulgil' was being used vaguely as representing material, matter, or substance without clear definition. This was problematic by reason that it could hinder students from having the concept of substance. Regarding the particulate nature of matter, molecule was introduced as a basic unit of matter at grade 7, prior to atom and ion, which were introduced at grade 9 and 10, respectively. It is necessary to reconsider the sequence of each particle concept to provide students with more consistent and comprehensive understanding of structure of matter. In the case of change of state, key concepts such as conservation of matter or reversibility were omitted in the curriculum document, and explanations based on various aspects of particles were somewhat insufficient. The concept of matter is fundamental to chemistry, and we must recognize it as a concept that needs to be taught clearly. Implications for curriculum revision were discussed.

• Journal of The Korean Association For Science Education
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• v.27 no.7
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• pp.663-675
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• 2007

Chemical reactions in cells are so complicated and abstract that students have difficulty in understanding them. In this study, classes with the application of systematic analogies used at the interpretation of experimental results were taught to 10th-grade students in order to help them to understand the concept of enzymes, which play an important role in chemical reactions in cells. Effects of the classes on their understanding of the concept of enzymes and the role of systematic analogies were analyzed. The gap of understanding between the test group and the control group was significant at 0.05, indicating that systematic analogies are effective for students' understanding of the concept of enzymes. Looking into the concept of enzymes by individual element, the effect of systematic analogies was shown to be large for equilibrium-like processes, such as the enzyme structure change caused by temperature and pH; and the continuous and random actions of enzymes, which students have difficulty in understanding. For these processes, systematic analogies played a positive role in improving their conceptual status. The visualizations and familiarity of analogs increased their intelligibility regarding the concept of enzyme. Also, the systematic analogies increases their plausibility by helping to connect phenomena, taking place in the enzyme reaction experiments, with scientific concepts as scaffold. Accordingly, it was possible to explain experimental results as scientific concepts in a consistent manner. In addition, analogies familiar to students played a positive role from the affective perspective by promoting students' interest and helping them to approach hard scientific concepts.