• Elastomers and Composites
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• v.54 no.4
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• pp.279-285
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• 2019

Bio-based polyester polyols were synthesized using esterification with azelaic acid, sebacic acid, and 1,3-propanediol. Polyurethanes were prepared using chain extenders (1,4-Butanediol, 1,3-Propanediol, and isosorbide) and 4,4'-diphenylmethane diisocyanate with a mixing ratio of 1:1:1.1. Subsequently, the properties of the polymers prepared using the different chain extenders were compared. The synthesis of polyurethane was confirmed by FT-IR, TGA, and GPC. The mechanical properties (hardness, ball rebound, and tensile strength) of the materials were analyzed using shore A tester, taber abrasion, and UTM. heat, chemical, and water resistances of the prepared materials were measured by comparing the tensile strengths according to external changes.

• The Mathematical Education
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• v.56 no.3
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• pp.319-340
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• 2017

The purpose of this study is to develop teaching and learning materials for the mathematics project inquiry subject. Since this subject is newly opened in the 2015 revised mathematics curriculum, there are no textbooks and materials. Hence it is required to help teachers plan lessons of the mathematics project inquiry subject. For this study, developing directions and objectives are established. Ten hours of lesson plan and teaching and learning materials are also developed for the two themes of 'big data' and 'industrial mathematics'. Suitability and validity of the developed material are verified positively from a survey of 8 teachers and 2 professionals. The detailed result findings are as follows. First, teaching and learning notes are suggested for each lesson plan. They are comprised of building inquiry plan, doing inquiry, summarizing results, and presentation. Second, driving questions of each theme are developed as "What is the big data and where is it used for ?" and "How various is the use of the industrial mathematics ?" respectively. Third, poster-types of each project product are developed. Fourth, three inquiry activity sheets and examples which are theme selection, inquiry plan, and group activity are developed. Fifth, 4 assessment sheets of self, peer, group, and teacher-use are developed.

• Journal of the Korean School Mathematics Society
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• v.25 no.4
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• pp.333-352
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• 2022

This study is aimed at developing the STEAM instruction materials for mathematics subject-based advanced technology and ICT teaching tools. In order to develop the STEAM materials, a PDI model in which the implementation and evaluation steps were simplified to Improvement was used. The developed STEAM materials were revised and supplemented by a group of experts. The subject of the STEAM class material developed in this study is 『Graph! The bridge that connects the past, present and future』 , 『You are the same but different!』 , 『Creating a virtual reality three-dimensional space together』 , 『And making interesting figures』 and 『Cover the roof of the turtle ship!』 . As a suggestion based on the results of this development study, various STEAM education materials should be developed and shared so that STEAM education can be performed in the elementary education field. And for the spread and settlement of STEAM education, the cultivation and expansion of STEAM education capabilities of on-site elementary school teachers or pre-service teachers will be an absolute prerequisite. And this suggests the need for a continuous and long-term approach to follow-up research on STEAM education.

• Korean Journal of Metals and Materials
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• v.50 no.12
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• pp.907-911
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• 2012

High purity silicon can be obtained from Al-Si alloys by a combination of solvent refining and centrifugation. Silicon purification by crystallization of silicon from an Al-Si alloy melt was carried out using 2N and 4N purity aluminum and 2N purity silicon as raw materials. The effect of the purity of raw materials on the final silicon ingot purity by centrifugation was investigated for an Al-50 wt% Si alloy. Alloys were melted using an electrical resistance furnace, and then poured into a centrifuging apparatus. A silicon lump like foam was obtained after centrifugation and was leached by an acid in order to get pure silicon flakes. Then silicon flakes were melted to make a silicon ingot using an induction furnace. The purities of the silicon flakes and silicon ingot were enhanced significantly compared to those of the raw materials of silicon and aluminum. The silicon ingot made of 4N aluminum and 2N silicon showed the lowest impurities.

• Korean Journal of Community Nutrition
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• v.11 no.4
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• pp.488-501
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• 2006

The purpose of this study was to develop various nutrition education materials, including an animated CD, for day care center children and their teachers and in order to apply the nutrition education programs systematically. We evaluated the effect of the nutrition education programs on nutrition knowledge in the first year, and the effect of the nutrition education programs on nutrition knowledge, food attitudes and eating behaviors in the second year in day care center children. In the first year, nutrition education foundational materials, such as the animated CD-ROM, videotape, textbook, panels, posters, slogans, leaflets, picture disks, hand puppets, stickers for compensation and poster boards were developed. The subjects were 537 children (286 boys,251 girls) aged four to six years. In the second year, nutrition education materials, such as the animated CD-ROM and textbook were developed. The nutrition education group included 368 children (177 boys 191 girls) aged four to six years, and the comparison group consisted of 108 children (54 boys,54 girls) Regarding the nutrition knowledge test results in the first year, the pre-test mean of children was 6.82, however, the post-test mean was 11.35 and showed a significant increase (p < 0.001). Regarding the nutrition knowledge test and the food attitude test results in the second yew, the nutrition education group had significantly higher scores than the comparison group in a post-test (p < 0.001). For the eating behavior test results, the post-test means between the comparison group and the nutrition education group were not significant. The test results show that several months of nutrition education is not enough to improve eating behaviors. As a result, nutrition education has improved nutrition knowledge and food attitudes in day care center children but short-term nutrition education was not sufficient to induce a change in eating behaviors. To improve eating behaviors in day care center children, nutrition education programs must be applied to day care center children in addition to their Parents and Persistent education will have to be continued.

• Communications of Mathematical Education
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• v.30 no.3
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• pp.335-351
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• 2016

The purpose of this study is to develop Project-Based Teaching-Learning materials for mathematically gifted students using a Fermat Point and apply the developed educational materials to practical classes, analyze, revise and correct them in order to make the materials be used in the field. I reached the conclusions as follows. First, Fermat Point is a good learning materials for mathematically gifted students. Second, when the students first meet the challenge of solving a problem, they observed, analyzed and speculated it with their prior knowledge. Third, students thought deductively and analogically in the process of drawing a conclusion based on observation. Fourth, students thought critically in the process of refuting the speculation. From the result of this study, the following suggestions can be supported. First, it is necessary to develop Teaching-Learning materials sustainedly for mathematically gifted students. Second, there needs a valuation criteria to analyze how learning materials were contributed to increase the mathematical ability. Third, there needs a follow up study about what characteristics of gifted students appeared.

• Education of Primary School Mathematics
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• v.26 no.1
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• pp.65-82
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• 2023

The purpose of this study is to examine how pre-service teachers' digital capabilities and content knowledge for teaching pi appear and are strengthened in the process of developing digital-based teaching and learning materials of pi, and to derive implications for pre-service teacher education. To this end, the researchers analyzed the process of two pre-service teachers developing exploratory activity materials for teaching pi using block coding of AlgeoMath program. Through the analysis results, it was confirmed that AlgeoMath' block coding activities provided an experience of expressing and expanding the digital capabilities of pre-service teachers, an opportunity to deepen the content knowledge of pi, and to recognize the problems and limitations of the digital learning environment. It was also suggested that the development of digital materials using block coding needs to be used to strengthen digital capabilities of pre-service teachers, and that the curriculum knowledge needs to be emphasized as knowledge necessary for the development of digital teaching and learning materials in pre-service teacher education.

• Journal of Korean Elementary Science Education
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• v.23 no.4
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• pp.305-317
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• 2004

The learning materials in elementary school science textbooks should include all kinds of materials being used by both teachers and students in the science teaching. The major purpose of this research is to analysis textbooks and teacher's guidebooks prepared for the science teaching of 3-6 grade students. To clarify this research, we listed whole of the learning materials of science teaching for each grade and counted numbers being used for whole of the lessons of science. And according to the characteristics and the methods of its preparation of materials, the types of learning materials can be divided into 10 categories such as teaching equipments for science, test materials, consumables, audio-visual aids, teaching equipments in general, collecting' recycling materials, field studies' collected data, breeding' cultivation materials, manufacture materials, and etc. At the result of this research, the 7th national science curriculum needs total 844 items of learning materials for science education. They could be separated into ten types of categories such as 159 items of teaching equipments for science, 65 items of test materials, 116 items of consumables, 198 items of audio-visual aids, 64 items teaching equipments in general, 31 items of collecting' recycling materials, 38 items of field studies (collecting) materials, 17 items of breeding-cultivation materials, 58 items of manufacturing materials, 105 items of other materials. And we found out that there were 332 items of materials for the 3rd grade, 303 items for the 4th grade, 324 items for the 5th grade, and 254 items for the 6th grade. The result of this research could be useful for classroom activities for science teaching.

• Journal of The Korean Association For Science Education
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• v.14 no.1
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• pp.12-23
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• 1994

This study was conducted to investigate the status and the problem of environmental education in schools. For this investigation, sub-goals to the general goal for environmental education such as knowledge, awareness, attitude, skill, participation, and evaluation were classified. The contents and objects of the environment-related chapters in elementary and secondary school science texts and of the materials for environmental education were analyzed. Resultingly, the content and objects focused on the cognitive domain such as knowledge and skill category in science texts($85{\sim}92\;%$) and in the materials for environmental education($70{\sim}84\;%$). The result indicated that the objects of the cognitive domain were heavily emphasized in the present environmental education.

• The Mathematical Education
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• v.53 no.3
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• pp.435-447
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• 2014

Recently, the interdisciplinary integration and story-telling are often mentioned in mathematics education. It is probably because they might be helpful to students for positive attitude for mathematics. In this research, through brief discussion mathematics related with wallpaper patterns, we try to integrate mathematics and design, and eventually develop the teaching/learning materials for experience activities and story-telling.