• Journal for History of Mathematics
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• v.21 no.3
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• pp.53-66
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• 2008

The concepts of ratio and proportion are familiar with students but have difficulties in use. The purpose of this paper is to identify the meanings of the concepts of ratio and proportion through investigating the historical development process of the meanings and representations of them. The early meanings of ratio and proportion were arithmetical meanings, however, geometrical meanings had taken the place of them because of the discovery of incommensurability. After the development of algebraic representation, the meanings of ratio and proportion have been growing into algebraic meanings including arithmetical and geometrical meanings. Through the historical development process of ratio and proportion, it is observable that the meanings of mathematical concepts affect development of symbols, and the development of symbols also affect the meanings of mathematical concepts.

• Journal of the Korean School Mathematics Society
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• v.11 no.2
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• pp.249-283
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• 2008

The purpose of the study was to investigate the definitions and concept images of Infinity and limits for high school students. In addition, the error patterns of the students were also investigated. The participants were 121 girls highschool students and survey method was used to co11ed data. Only 11 % and 5% of the participants revealed the definitions similar to the standard textbook definitions in limits of infinite sequences and infinite series respectively. The participants showed 6 types of error patterns and had more difficulties in understanding and applying concepts and properties of infinite series than those of infinite sequences.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.661-663
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• 2013

The purpose of the following report is to introduce a model that makes it possible to efficiently search data by using keyword-based concept network for reliable access of information which is rapidly increasing in the mobile cloud. A keyword-based concept network is a method with the application of ontology. However, the proposed model is added by association information between keyword concepts as a method for a user's efficient information retrieval. Furthermore, the proposed concept network consists of the keyword centered concept network, expert-group-recommended field concept network, and process concept network.

• Journal of Aerospace System Engineering
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• v.11 no.5
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• pp.50-55
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• 2017

This research describes the ConOps(Concept of Operations) of sea-based guided weapon systems. The ConOps describes how the proposed system is to be used and is more descriptive than technical in terms of various stakeholders. It should be prepared to support the concept of the life cycle stage of the system. Developing ConOps plays an important role in ensuring that operational/maintenance, maintenance, and acquisition and development areas are better understood by users' needs and expectations. In this point of view, this work presents the process of deriving ConOps and aims to derive operational concept of maritime guided weapon system by using tools.

• School Mathematics
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• v.19 no.3
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• pp.495-511
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• 2017

The purpose of this study is to research the meaning of core ideas and to compare the core ideas in mathematics curriculum of each country. I derived that the core ideas were approached and presented in curriculums of South Korea, The United States, Canada, Australia, New Zealand, Singapore as several perspectives; the main domains of mathematics contents which should be taught; the basis of the core principles between of mathematical contents; the focuses for teaching and learning in school mathematics. Finally, I discussed the further research direction on the contents of core ideas and the methods of presenting it to teach meaningfully the core mathematical contents to students who will live in the future.

• Korean Journal of Child Education & Care
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• v.17 no.4
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• pp.187-208
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• 2017

This study surveyed 60 early childhood teachers at the kindergartens and day care centers in Incheon Metropolitan City to examine the contents and extent of the teachers' knowledge on early childhood history education by using the definition map designed by Novak and Gowin(1984). To be more specific, the researcher asked the participating teachers through group meetings to draw the definition maps and analyzed them. The results were as follow. First, 11 categories for high level definition of early childhood history education used by early childhood education were identified, among which the most frequently used high level definition were 'life style' followed in order by 'culture/art' and 'great men.' Second, in terms of the average number of dependent definitions included in the given high level definitions, the largest was 'life style' which was followed in order by culture/art, activity methods. It means that the widest area of early childhood teachers' knowledge on early childhood history education was about 'life style,' while it shows that the extent of knowledge on teaching-learning methods was relatively wide. However, in the case of great men, although it was frequently recognized in the high level of definition it was not so in the dependent definitions, meaning the extent of their knowledge was rather narrow. Scholars explain that the higher the teachers' attention and knowledge about the content of curriculum the more options of teaching method they tend to employ to teach in a more extensive and diverged way. Therefore, in order to improve early childhood education, efforts should be more focused on deepening and systemizing the knowledge of early childhood teachers.

• Journal of the Korean Chemical Society
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• v.48 no.4
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• pp.399-413
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• 2004

In this study, a survey was conducted of students of elementary through college on their conceptions of phenomenon related with dissolution, saturation, and extraction. The teaching strategies of elementary and secondary teachers related to dissolution phenomena were also investigated. Most of elementary and secondary school students thought of dissolution as a phenomenon in which particles broke into the spaces between other particles. This explanation called 'space conception' can be sought in elementary school science textbooks. Some of high school students also had this type of thought. A concept of dissolution phenomenon as 'hydration through attraction of solvent and solute' was held by most of students of 11th, 12th grade, and college. This explanation called 'attraction concept' can be sought in high school chemistry textbooks for 11th and 12th grade. But many students of elementary through college used analogies and models related to 'space conception' when they tried to explain the dissolution phenomena. This indicates that the 'attraction concept' was not firmly established in the students' cognition. 90% of elementary school teachers thought and taught dissolution as a phenomenon in which two different size particles were mixing together like as mixing beans and millets. The model does not represent the attractions among solvent-solvent particles, solvent-solute particles, and solute-solute particles. This model only represents the space size effect (smaller size particles fitting into the spaces of larger size particles). Half of the secondary school teachers also had 'space conception' and only 20% of the teachers had 'attraction concept' Many teachers who had 'attraction concept' used to represent explanation related to 'space conception' for teaching dissolution.

• Journal of the Korean earth science society
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• v.35 no.4
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• pp.267-276
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• 2014

The purpose of this study is to investigate the effects of problem-solving inquiry teaching using concept sketches on conceptual changes about plate tectonics and science-related attitudes. The subjects of this study were two classes of second-year students of K high school located at Anseong in Gyeonggi Province. Before instruction, a conceptual test was conducted to survey student's preconceptions about plate tectonics. The control group took a traditional lesson, while the experimental group was applied to problem-solving inquiry teaching using concept sketches. After the inquiry instruction, TOSRA (Test of Science-Related Attitudes) was administered to find out changes in science-related attitudes of the two groups. The results of this study are as follows. The experimental group understood concepts of plate tectonics better than the control group, which means that problem-solving inquiry teaching using concept sketches was more effective in students' conceptual understanding. Science-related attitudes of the experimental group showed a significant change in the categories of 'normality of scientists', 'pleasure of science lessons', and 'interests on science as a hobby'. In conclusion, the instruction of problem-solving inquiry using concept sketches produced students' positive changes in conceptual understanding about plate tectonics and science-related attitudes.

• Journal of The Korean Association For Science Education
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• v.20 no.1
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• pp.77-87
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• 2000

The purpose of the study is to understand the change process of middle school students' physics conceptions by the presented types of conflict situations. 274 middle school students were selected from one school in Pusan, however 257 students were participated in all the procedure of the study. After we classified students' physics conceptions into scientific and unscientific conceptions, presented three types of conflict situations. In this study three different cognitive conflict strategies were adopted; the first one is logical arguments(LCS: logical conflict situation), the second is actual demonstration(DCS: demonstrational conflict situation), and the third is two strategies together(DLCS). In this study, first, we investigated the change process of students' physics conceptions by three types of conflict situations. Second, we compared the effect of three conflict situations presentation, which includes positive effect by conceptual change from misconception to scientific conception and negative effect by conceptual change from scientific conception to misconception. Third, we studied characteristics of conceptual change by characteristics of conflict situations. In result, DLCS group and DCS group were more positive effect than LCS group in mechanics, DLCS group and LCS group were more positive effect than DCS group in electricity. It seems that mechanics are closely related to physical experiences, while electricity are more abstract.

• Journal of The Korean Association For Science Education
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• v.34 no.5
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• pp.449-457
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• 2014

Recent studies have shown that teachers should have be aware of and understand students' misconceptions, which is one of the major components of PCK. However, teachers often have difficulties in understanding misconceptions and in applying appropriate instructional strategies to change misconceptions. Thus, we designed a method course for pre-service teachers (PSTs) adapting the concept of "teacher as researcher". In the course, PSTs conducted research to investigate students' misconceptions in physics. Twenty-five female PSTs participated in the study. They went through the research process including creating question items, administering items to their target populations, collecting and analyzing student responses, and writing a research paper. Data source included individual interviews with the PSTs, field notes during classroom observation and PSTs' research papers. The results were as follows. First, the PSTs confirmed students' misconceptions and learning difficulties in physics. They experienced discrepancies between their conjecture and research findings. Second, PSTs developed the sophisticated understanding of students' misconceptions and appropriate teaching strategies. Third, the research experience provided the PSTs opportunities to reexamine their physics content knowledge while creating items and explaining scientific concepts. They realized that physics teachers should develop sound understanding of physics concepts for guiding students to have less misconception. Lastly, they realized the necessity of being a teacher as a researcher.