• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.131-133
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• 2004

본 연구는 출력단에 패캐시터를 갖고 있는 AC 전류원으로부터, 밧데리 충전을 위한 새로운 AC/DC 컨버터 회로를 제안한다. 영전압과 영전류 스위칭을 사용하여 컨버터의 소형화 및 고효율화를 추구하였고, 풀브리지 MOSFET 정류기와 Buck-boost 컨버터가 결합된 새로운 토폴로지의 회로를 구성하였다. 제안된 컨버터의 동작원리 및 동작모드를 해석하고, PSpicc 시뮬레이션을 통해 해석결과를 검증하였다.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.68-71
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• 2004

본 연구는 저전압 AC 전류원으로부터 밧데리 충전을 위한 에너지 변환회로를 제안한다. 전체 시스템의 소형화 및 고효율화를 추구하기 위해서, 풀브리지 MOSFET 정류기와 부스트 컨버터로 회로를 구성하였다. 제안된 컨버터 시스템의 동작원리 및 동작모드를 해석하고, 시뮬레이션을 통해 해석결과를 검증하였다.

• Korean System Dynamics Review
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• v.15 no.4
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• pp.29-60
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• 2014

As every commentators has noted, bureaucratic corruption, which has complicated causes, is prevalent phenomenon in Korean society. Especially, most people realize that systemic corruption has a strong negative effect on society; however, only few studies reflect on the nature of 'systemic corruption' and it seems that no established theory explains the phenomenon. Thus, this study suggest that we look more carefully into the nature and mechanisms of 'systemic corruption'. Interdisciplinary approach based on the integrated model of structure-behavior to analyse the nature of bureaucratic corruption. The system dynamics method can test the mechanisms of 'systemic corruption'. With this way, the factors generating systemic corruption represent the relationships reinforcing and balancing within system dynamics model. This paper also consider 'isomorphism' and 'dominance' as control mechanisms to systemic corruption. From the CLD(Causal Loop Diagram), three main areas(rent in organization, networking, control mechanisms) are overlapped and it indicates dynamic relationships of systemic corruption in organizations.

• Archives of design research
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• v.12 no.3
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• pp.191-200
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• 1999

The purpose of this study is to analyze traditional stereo images (stereopsis), and study electronic methods to create stereo images using computer graphics technology on visualization of computer. Computer system can process image data and show results on its display. In the early days of computer era, most scientific research data was printed on paper as a procession of digits. These days, the visualization of computer graphics has a precise and realistic quality in its imaging technology. Some technological advances have been developed to not only display 2-dimensional geometry but also 3-dimensional stereo images to simulate virtual reality. In this study, [ have discussed the history of stereopsis, principles of stereo images and technological developments. Also I analyzed the components of stereo images, optical and electronic methods and visual systems which are used in computer graphics technology. I developed my own theories on possibilities for new methods of 3-dimensional stereo images.

• Journal of The Korean Association of Information Education
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• v.3 no.2
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• pp.85-93
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• 2000

The good courseware must have the me끼ts of computer and must be designed according to principles of instruction. Therefore, we propose a model of learning structure for tutorial web courseware on the basis of elaboration theory that can give us the suitable design strategies of contents for web courseware. This model is suited to the level learning and individual learning because it is constructed of six factors - epitome, precedence learning, basis learning, depth learning, summarizer, synthesizer. We also make a tutorial web courseware to apply this model and evaluate effects in comparison with the existing tutorial web coursewares.

• Journal of Elementary Mathematics Education in Korea
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• v.19 no.3
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• pp.435-455
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• 2015

This study is aimed at analyzing the level change and features of mathematical communication in elementary students' expository writing. 20 students of 5th graders of elementary school in Seoul were given expository writing activity for 14 lessons and their worksheets was analyzed through four categories; the accuracy of the mathematical language, logicality of process and results, specificity of content, achieving the reader-oriented. This study reached the following results. First, The level of expository writing about concepts and principles was gradually improved. But the level of expository writing about problem solving process is not same. Middle class level was lower than early class, and showed a high variation in end class again. Second, features of mathematical communication in expository writing were solidity of knowledge through a mathematical language, elaboration of logic based on the writing, value of the thinking process to reach a result, the clarification of the content to deliver himself and the reader. Therefore, this study has obtained the conclusion that expository writing is worth keeping the students' thinking process and can improve the mathematical communication skills.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.1
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• pp.70-77
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• 2005

A new converter to transfer energy from a low-voltage AC current source to a battery is proposed. It is focused to find operational modes of the converter. The low-voltage AC current source is an equivalent of the piezoelectric generator, which converts the mechanical energy to the electric energy. The converter consists of a full-bridge MOSFET rectifier and a MOSFET boost converter in order to make the converter small and efficient. The operational principle and modes of the converter are investigated with the consideration of effects of the parasitic capacitances of MOSFETs and diode. The results are proved with simulation studies using PSIM and Pspice.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.334-342
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• 2016

This study performed an appreciative inquiry into models of instruction for the community learning. For this purpose, this study examined the principle of learning, instruction models for community learning, and appreciative inquiry. Next, draft appreciative inquiry models were built based on the principle of instruction models for the community learning. The previously designed appreciative inquiry models were revised and complemented through expert investigation by a focus group interview. This paper proposes a process of seven steps core learning activities. The seven steps were selecting a theme, interviewing for finding success story, analyzing an organization's success stories and deriving the core values, deriving future of the organization, sharing future of the organization, designing the ideal future of the organization consist of a practice, implement, and reflect. Because the proposed seven steps process is based on the literature and focus group interview, a follow-up study will be needed to verify the result.

• Journal of Science and Technology Studies
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• v.10 no.2
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• pp.143-174
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• 2010

How can a regulatory policy to address potential hazards be made legitimate in the face of scientific uncertainty? The precautionary principle has been gradually regarded as the most persuasive answer to this intricate question in Europe since the 1970s and generally recognized as a guiding principle in international environmental law. This principle, however, has often been subject to diverse concerns and criticisms due to its vague definition. This article tries to elaborate the precautionary principle while reviewing both the validity and unreasonableness of these criticisms over this principle. Then, this article explores the policy relevance of this principle by applying this elaborated definition to the concrete case of risk governance such as the risk assesment of food safety. In the end, this paper emphasizes the fact that the precautionary principle can be applied in the field of risk governance, refuting the argument that the precautionary principle is only a moral attitude or a political position.

• Convergence Security Journal
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• v.22 no.3
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• pp.3-11
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• 2022

With increasingly sophisticated cyber threats, accelerating cloud adoption, and the adoption of remote and hybrid work environments due to the COVID-19 pandemic, the traditional security model, in which many businesses implicitly trust everything within their boundaries, is changing without boundaries, allowing data and users The concept of zero trust is getting more and more attention as the fact that it is not suitable for today's increasingly decentralized environment has been highlighted. Zero Trust is a cyber security model on the premise that 'no one trusts'. In principle, there is no safe area or user in the entire system, and internal users are also verified. is a way As telecommuting becomes commonplace due to the COVID-19 pandemic, and existing cyber security measures are facing limitations, Zero Trust technology is drawing more attention. Accordingly, it is expected that the Korean government will also check the status of acceptability of the domestic public and private sectors and tasks that need improvement when introducing Zero Trust with reference to the NIST standard. In this paper, the basic principles, philosophy, and considerations of Zero Trust and Zero Trust are explained, and practical basic measures to strengthen security by combining Zero Trust technology are presented.