• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.557-558
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• 2006

In all conventional sintered PM products, the pores present are of two types, primary and secondary. Primary pores forming during compaction and latter during sintering, due to penetration of formed liquid through the matrix grain boundary. Effect of carbon addition on diffusion of Cu in SH737-2Cu system was investigated. After compaction and transient liquid phase sintering at $1120^{\circ}C$ and $1180^{\circ}C$, samples were characterized for densification, showing rise in sintering density and reduction in swelling on carbon addition. Quantitative microstructural characterization (shape factor and pore size) revealed bimodal distribution for 0% carbon, more rounded pores for 0.9% carbon and higher sintering temperature, and pore coarsening at higher sintering temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.426-426
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• 2007

We report the field emission characteristics of transparent single-walled carbon nanotube (SWNT) film printed using an inkjet. Pure SWNTs dispersed in dimethylformamide were printed in a transparent layer on indium-tin oxide-coated glass and annealed at $350^{\circ}C$. After taping treatment, SWNTs were oriented vertically on the substrate. The front and the back of the fabricated device produced simultaneous emissions of identical quality. In addition, inkjet printing directly achieved a patterned emission, without a secondary pattern process. This method allows simple fabrication using only SWNTs, without the use of other additives.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.5
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• pp.211-217
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• 2021

To predict mechanical properties of secondary hardening martensitic steels, a machine learning ensemble model was established. Based on ANN(Artificial Neural Network) architecture, some kinds of methods was considered to optimize the model. In particular, interaction features, which can reflect interactions between chemical compositions and processing conditions of real alloy system, was considered by means of feature engineering, and then K-Fold cross validation coupled with bagging ensemble were investigated to reduce R2_score and a factor indicating average learning errors owing to biased experimental database.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.39-44
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• 2019

This study renewed the 'RE_Double Diamond' design process on the importance that material selection should reflect the needs of the consumer as much as possible in product development. In addition, the provider-centered secondary stakeholder map process among existing double-diamond methodologies has been applied, and the selection of materials through communication between designers and engineers, including the construction of information focused on visualization.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.2
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• pp.57-60
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• 2019

The impact of two-step treatment on the mechanical properties of the 6061 Al alloy was investigated by testing the hardness and electrical conductance values. After two-step aging treatment, the hardness and electrical conductivity of the alloy was increased, and if the first aging treatment temperature was lower than the secondary aging treatment temperature, both the hardness and the electrical conductivity were not increased. The higher the temperature of the first aging treatment, the higher the hardness. The temperature of the first aging treatment is $175^{\circ}C$, $150^{\circ}C$, $120^{\circ}C$, and the second is $175^{\circ}C$ and $120^{\circ}C$.

• Communications of Mathematical Education
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• v.29 no.3
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• pp.465-489
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• 2015

The purpose of this study is to suggest implications for the development and revision of future teaching materials for mathematically gifted students by using network text analysis of secondary mathematics materials. Subjects of the analysis were learning goals of 110 teaching materials in a gifted education center in science attached to a university from 2002 to 2014. In analysing the frequency of the texts that appeared in the learning goals, key words were selected. A co-occurrence matrix of the key words was established, and a basic information of network, centrality, centralization, component, and k-core were deducted. For the analysis, KrKwic, KrTitle, and NetMiner4.0 programs were used, respectively. The results of this study were as follows. First, there was a pivot of the network formed with core hubs including 'diversity', 'understanding' 'concept' 'method', 'application', 'connection' 'problem solving', 'basic', 'real life', and 'thinking ability' in the whole network from 2002 to 2014. In addition, knowledge aspects were well reflected in teaching materials based on the centralization analysis. Second, network text analysis based on the three periods of the Mater Plan for the promotion of gifted education was conducted. As a result, a network was built up with 'understanding', and there were strong ties among 'question', 'answer', and 'problem solving' regardless of the periods. On the contrary, the centrality analysis showed that 'communication', 'discovery', and 'proof' only appeared in the first, second, and third period of Master Plan, respectively. Therefore, the results of this study suggest that affective aspects and activities with high cognitive process should be accompanied, and learning goals' mannerism and ahistoricism be prevented in developing and revising teaching materials.

• Journal of Gifted/Talented Education
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• v.12 no.2
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• pp.31-56
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• 2002

Providing gifted education should be based on the principle of differentiation, that is, paying close attention to the individual characteristics of the gifted. The gifted are known to be the fast learners with autonomous studying ability and high levels of thinking and creativity, which certainly differentiate them from the ordinary others. Thus, the program for the gifted should fundamentally differ from other general programs. The need for gifted education is growing as our society has turned into the knowledge-based society. Fortunately, on December 28th, 1999, a law in favor of gifted education was passed. According to the law, gifted education will be actively provided under the government's support from the year 2002. In this context, this study is intended to search for the model of developing instructional materials for the gifted. The output materials of this study are to be used in gifted schools which will be built in the near future. The curriculum for the gifted consists of three parts: basic curriculum, in-depth curriculum, and optional curriculum. The learning and instructional materials developed in this study are to be used for the in-depth curriculum. In order to develop the materials, various theoretical models related to gifted education were reviewed. Finally, a theoretical model was developed. On the basis of the model, several instructional materials are developed and the possibility of application are considered.

• International Journal of Quality Innovation
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• v.8 no.3
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• pp.123-155
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• 2007

This research treated the secondary school teachers as the research scale and the research targets included the following: secondary school (employ unit), center of teacher education, and qualified teachers. In terms of these three groups of people, the topics of exploration focused on the perception of suitable teachers, perception of evaluation standard during the process of teacher examination and the relationship among teacher examination systems. The research was managed by two phases: the first phase referred to literature reorganization, expert interview, the qualities and conditions of suitable teachers, important evaluation standard during the process of teacher examination and teacher examination system used; the second phase included questionnaire survey, employ school acquisition, the perception of centers of teacher education and qualified teachers toward the suitability condition and examination evaluation standard in the first phase and teacher examination system used. This research found out that as to the perception of suitable teachers, through data collection, there were six factors reorganized. The levels of their importance were as follows: education devotion, teaching capacity, class management, capacity to guide special students, capacity to communicate with the parents and the will to undertake administrative works. Noticeably, employee unit and centers of teacher education apparently valued class management more, compared with trained teachers; as to evaluation standard of examination, the analytical result found out that the perception of three groups were different in terms of the views toward educational works, written examination data, candidate's age, club experience at school and capacity to use multimedia support teaching materials. This research further proposed six suggestions for centers of teacher education and trained teachers: (l) employ schools considerably valued educational devotion; (2) trained teachers tended to neglect the importance of class management; (3) employee unit considerably cared about the new teachers' competence to use multimedia support teaching materials; however, trained teachers did not have the same view; (4) employee unit considerably cared about new teachers' views toward educational works as well as the candidates' ages; (5) generally speaking, trained teachers neglected the importance of club experience at school; (6) the data revealed that written examination data was not relatively important in terms of teacher examination.

• Journal of Korean Library and Information Science Society
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• v.49 no.3
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• pp.55-75
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• 2018

The purpose of this study is to identify characteristics of secondary school teachers' perceptions and experiences of school libraries and to suggest strategies for its' activation. In order to achieve this aim, the questionnaire survey was conducted for 229 secondary school teachers who participated in K university qualification training in 2017. As a result, they recognize that school libraries are an essential facility and that continuous support and investment are needed. They think that the effectiveness of the school library is very helpful for creating a leisure and cultural life and for stimulating reading atmosphere and education, and this perception is stronger at lower ages. The number of school library use of them is as low as once a month, and the purpose of use is mainly for cultivation and leisure. The discomfort of the school library is mostly due to lack of materials and space for them. In particular, they have a lack of knowledge and necessity about the method of library-based instruction and insufficient preparation time and poor materials. Teachers are highly aware of the need and utility of training, and prefer training with peers. Therefore, it is necessary to develop strategies such as remodeling space and increasing collections for their study and instruction, and foster peer supervision so that they can actively utilize school library in subjects management.

• Korean Journal of Health Education and Promotion
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• v.9 no.2
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• pp.12-40
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• 1992

The study is designed to grasp school adminstrators' attitudes toward school health education and practices of school health education and to analyse relationships between characteristics of school administators and their attitudes to school health education and between their attitudes and practices of school health education in elementary and secondary schools, so that it may offer the basic materials for improving the school health education. This study was obtained from 740 school administrators all over the country, who have attended Certification Training of Elementary and Secondary Principal opened at Korea National University of Education from July, 1, 1991 to August 9, 1991. The results are summarized as follows: 1. School administrators' attitudes toward school health education 1) As for view of health education, those who believed that health is the means of education was 36.2%. 2) In methods of school health, those who want regular health education was 75% ; irregular health education 25%. 3) As for attitudes of those chose irregular health education as teaching methods : (1) In teaching hours, the morning and afternoon class meetings was highest 50.8% of whole. (2) In teaching staffs, home room teacher was 51.9% ; school nurse 34.8%. (3) In frequency of irregular health education, 1-2 times a week was 38%, 1-2 times a month 32.6%, 1-2 times a semester 11.8%. (4) As for teaching methods of irregular health education, practice through the health function showed higher frequency than other methods 4) As for attitudes of those chose regular health education as teaching methods : (1) Most of respondents had opinion that regular health education should be carried out by the subject of physical education in both elemetary and secondary schools. (2) Opinion that school nurse should be in charge of regular health education was a little higher than other ones. (3) More than a half of the whole thought that 1-2 hours a month was suitable for carrying out regular health education. (4) Therr-fourth of those who wanted regular health education chose the using of audiovisual material as a teching method. (5) Curriculum recommended first by respondents for the school health education were personal habits and health, prevention and control of disease, mental and emotional health etc. (6) As for impedimental factors in the development of school health education, it was shown as following order : the lack of professional health education instructors, the lack of budget and administrative support, the lack of instructional materials and instruments etc.