• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.109-117
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• 2000

A full bridge type double resonant high frequency resonant inverter to give VVVF function in the inverter used as power source of induction heating at high frequency is presented in this paper. This proposed inverter can reduce distribution of the switching current because of using the current of serial resonant circuit to the input current of the parallel one and this paper also realize the output control of independence irrespective of the switching frequency using Phase-shift. The analysis of the proposed circuit is generally described by using the normalized parameters. Also, the principle of basic operating and the its characteristics are estimated by the parameters, such as switching frequency, the variation of phase angle ($\phi$) of Phase-shift.

• Korean Journal of Health Education and Promotion
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• v.24 no.5
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• pp.1-21
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• 2007

Adolescent psychosocial smoking prevention programs have been successful, but limited in the magnitude of program effects. The present study is the secondary analysis after the previous study estimated mean effect sizes in smoking knowledge, attitudes, skills, and behaviors with treatment variables. Regardless of overall program effect estimations that other meta.analysis studies have done, this study is conducted to identify explanatory variables that are likely to increase program effects. A decrease of adolescent smoking behaviors is associated with the following factors: a. Younger students ($5^{th}-7^{th}$) than older students ($8^{th}-12^{th}$). b. Research methodology using true experimental design, quasi experimental design with equivalence between groups, use of random assignment, 10% or less attrition rate, use of a no treatment control group, high implementation fidelity, and/or acceptable instrumentation reliability. c. Programs using trained peer leaders, targeting cigarette smoking only, implementing 10 or more treatment sessions and/ or providing booster sessions.

• Journal of Korean Society of Steel Construction
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• v.19 no.1
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• pp.117-127
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• 2007

In this study, we evaluate the strength of steel box beam-to-column connections subjected to axial loads in steel frame piers. The T-connection strength was reduced due to the column axial force in the two-story pier structure. To examine this phenomenon, non-linear FEM analysis was carried out and the analytical procedure was verified by comparing it with experimental results. To clarify the effect of the axial force and major design parameters in connection with strength, influence of panel zone width-thickness ratio, sectional area, and axial force was investigated using FEM analysis. Also, the theoretical strength equations were suggested by stress distribution of panel zone. The strength of the T-connection was compared with one of the one-story pier structure connections. As a result, the strength evaluation equations are proposed in consideration of the panel zone width-thickness ratio and sectional area ratio for the T-connections.

• Informatization Policy
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• v.19 no.4
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• pp.3-26
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• 2012

The purpose of this study is to provide a systematical view point of SNS research published by scholarly journals in communications vis a meta-analysis. A total of 72 articles dealing with SNS issues from 2006 to 2012 were analysed by research theme, related sub-theme, methodology, theoretic rationale, targeted media, and characteristics. Effect research get the largest portion and then user research in terms of a developmental model of media research agenda. A major methodological trend is an online survey and theoretical background is Uses and Gratification. Twitter is the most popular medium researched and SNS is mainly characterized as information provision and seeking as well as relationship forming.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.1
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• pp.90-97
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• 2001

A high frequency resonant inverter consisting of iliree unit Half-Bridge serial resommt inverter used as power source of induction heatmg at high frequency is presented in this paper. As a output [Dwer control strategy, sequencial time-sharing gate contml methcd is applied. This methcd is TDM(Time Division Multiplexing), which is broadly used with digital and analog signals transmission in communication system 1be analysis of the proposed circuit is generally described by using the normalized pararmenters. Also, the principle of basic operating and the its characteristics are estimated by the parameters such as switching frequency, load resistance. Also, according to the calculated characteristics value, a method of the circuit design and operating characteristics of the inverter is proposed. This paper proves the validity of theoretical analysis through the Pspice. This proposed inverter show that it can be practically used in future as power source system for induction heating application, DC-DC converter etc. r etc.

• Journal of Korea Technology Innovation Society
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• v.20 no.4
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• pp.888-914
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• 2017

The main aim of this study is a meta-theoretical investigation to explain the current theoretical landscape of social innovation theories and researches. First of all, this paper makes a typology of social innovation based on concepts and sectors of social innovation. Second, in terms of societal innovation, which it is a kind of social innovation systematic approach, this paper draws some implications for social innovation policy. My key argument is that social innovation could be specified in three different sectors, public innovation, market innovation, and social economy innovation. However, all of them have attention to such as improving a quality of life and making society more sustainable, so it can be argued that those different sectors are structured on social innovation altogether with common goals. Finally, in order to activate the social innovation ecosystem, the government has to play a key role as a facilitator to make sustainable networks and a governance of social innovation that is needed to coordinate between different features and roles of social innovation sectors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.140-141
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• 2017

Big data analysis, in the large amount of data stored as the data warehouse which it refers the process of discovering meaningful new correlations, patterns, trends and creating new values. Thus, Big data analysis is an effective analysis of various big data that exist all over the world such as social big data, machine to machine (M2M) sensor data, and corporate customer relationship management data. In the big data era, it has become more important to effectively analyze not only structured data that is well organized in the database, but also unstructured big data such as the internet, social network services, and explosively generated web documents, e-mails, and social data in mobile environments. By the way, a meta analysis refers to a statistical literature synthesis method from the quantitative results of many known empirical studies. We reviewed a total of 750 samples among 50 studies published on the topic related as IDT between 2000 and 2017 in Korea.

• Fashion & Textile Research Journal
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• v.25 no.5
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• pp.578-592
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• 2023

This study identified and evaluated by deriving and categorizing concepts related to the user experience of metaverse fashion shows using grounded theory, which is a qualitative research method. Based on experiential marketing theory, in-depth interviews were conducted for 14 days with 14 males and females in their 20s and 30s. The research results and contents are as follows: The causal condition was the purpose of using metaverse fashion shows, and the action/interaction strategy caused by such a case was found to be establishing a system for metaverse fashion shows and promoting a positive brand image. The results included content evaluation of satisfaction, normal, or dissatisfaction. The contextual condition was a change in the form of consumption that emphasized experience, while the interventional condition was psychological distance. Based on this, the core category was defined as "consumption patterns that emphasized the purpose of use and experience affects the metaverse fashion shows and psychological distance appeared as a user experience evaluation through the establishment of a system of metaverse fashion shows and the promotion of a positive brand image". User types were classified as active or passive. Active users have the autonomy to select content according to their individual preferences, and accordingly, their experience preference tends to change. In contrast, passive users' preference for the technical quality of content is relatively low, but they have a high concentration of content diversity and audio-visual interest elements.

• Journal of Educational Research in Mathematics
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• v.26 no.2
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• pp.173-188
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• 2016

Research on didactic transposition in mathematics education has about 25-year and about 35-year long history in and out of Korea, respectively. This study attempts to investigate in trends of those research and to suggest tasks needed to be tackled. Major findings are followed. First, studies done in Korea tended to focus on the application of the didactic transposition theory for proving its effectiveness in understanding mathematics textbooks and mathematics lessons in-depth. It is suggested to conduct meta-analysis of the accumulated results or analysis of further applications of the didactic transposition theory to improve theoretical aspects of didactic transposition. Second, new categories for extreme teaching phenomenon were found and new typology in knowledge to be considered in the didactic transposition was developed in a few studies done in other subject matter education. Application of these to mathematics education may enhance research in didactic transposition of mathematical knowledge. Third, praxeology or a complex of praxeology for Korean school mathematics should be explored as did in other countries. Fourth, there have been rich attempts to link perspectives in didactic transposition to other perspectives or fields such as anthropology, human and education in technology era, praxeology theory in economics, epistemology in other countries but not in Korea. It is suggested to extend the scope of discussion on didactic transposition and to relate various concepts given in other disciplines. Fifth, clarification or negotiation of meaning for the main terms used in the discussion on didactic transposition such as personalization, contextualization, depersonalization, decontextualization, Topaze Effect, Meta-Cognitive Shift is suggested by comparing researchers' various descriptions or uses of the terms.

• Journal of The Korean Association For Science Education
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• v.26 no.4
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• pp.475-491
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• 2006

In physics education, the research on students' conceptions has developed in the discussion on the nature and the difficulty of conceptual change. Recently, mental models have been a theoretical background in concrete arguments on "how students' conceptions are constructed or created." Mental models that integrate information in the presented problem and individual knowledge in their long-term memory have important information about not only expressed ideas but also in the thinking process behind the expressed ideas. The purpose of this study is to investigate the forming process and the characteristics of high school student's mental models about circular motion, and how they were changed by instruction. We used the think-aloud method based on the instrument for identifying student's mental models about circular motion, pretest of physics concept, mind map and interview for investigating student's characteristics. The results of the study showed that instructions based on the mental model theory facilitated scientific expressed model, but several factors that affected forming mental models like epistemological belief didn't change scientifically after 3 lessons.