• JOURNAL OF ELECTRICAL WORLD
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• no.1 s.109
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• pp.25-29
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• 1986

• JOURNAL OF ELECTRICAL WORLD
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• no.2 s.110
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• pp.18-23
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• 1986

• Proceedings of the Korean Sanitation Conference
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• 2001.06a
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• pp.1-20
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• 2001

• 축산식품과학과 산업
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• v.2 no.2
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• pp.8-16
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• 2013

• Journal of Power Electronics
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• v.16 no.6
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• pp.1991-2004
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• 2016

An LC filter is required to reduce the output current ripple in the auxiliary resonant snubber inverter (ARSI) for high-performance applications. However, if the traditional control method is used in the ARSI with LC filter, then unnecessary current flows in the auxiliary circuit. In addressing this problem, a novel load-adaptive control that fully uses the filter inductor current ripple to realize the soft-switching of the main switches is proposed. Compared with the traditional control implemented in the ARSI with LC filter, the proposed control can reduce the required auxiliary current, contributing to higher efficiency and DC-link voltage utilization. In this study, the detailed circuit operation in the light load mode (LLM) and the heavy load mode (HLM) considering the inductor current ripple is described. The characteristics of the improved ARSI are expressed mathematically. A prototype with 200 kHz switching frequency, 80 V DC voltage, and 8 A maximum output current was developed to verify the effectiveness of the improved ARSI. The proposed ARSI was found to successfully operate in the LLM and HLM, achieving zero-voltage switching (ZVS) of the main switches and zero-current switching (ZCS) of the auxiliary switches from zero load to full load. The DC-link voltage utilization of the proposed control is 0.758, which is 0.022 higher than that of the traditional control. The peak efficiency is 91.75% at 8 A output current for the proposed control, higher than 89.73% for the traditional control. Meanwhile, the carrier harmonics is reduced from -44 dB to -66 dB through the addition of the LC filter.

• Journal of Korea Technology Innovation Society
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• v.19 no.2
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• pp.358-394
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• 2016

In Korea, co-utilization of research equipments has been low, even though co-utilization policies for them have been implemented for a long time. This situation results because the policy formation and implementation for the co-utilization of research equipments have been conducted from the perspectives of the policy maker not from those of the researchers and equipment managers. Therefore, this work has been conducted for analyzing the current state of co-utilization of research equipments as well as for discussing the future developments of its more co-utilization in the basic research programs by adopting the bottom approach in policy implementation theory. The research shows that firstly principal investigators, especially professors in universities, have placed a relatively low priority on the co-utilization of research equipments, secondly implementation resources such as high quality technicians and affordable budget for co-utilization are scare, thirdly incentives for the activation of co-utilization in the stage of daily operation of research equipments are lacking. As a result, the study tries to develop a more economic means and information tools for the promotion of co-utilization of research equipments in the perspectives of bottom-up approach in policy implementation theory.

• Journal of The Korean Association of Information Education
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• v.8 no.2
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• pp.271-279
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• 2004

With changing to the new information technology society, education has also been urged to utilize the Information Ccmmunication Technology(ICT). Thanks to the recent efforts by the government, a large number of schools has been equipped with advanced educational technologies. While there has been a lot of studies on how to use ICT more effectively, relatively few is the studies about the activating factors of ICT utilization. More than often than not, those studies have been conducted about the survey of current situations of ICT utilization and have never had implemented based on the theory of diffusion of innovation. As a result, the current study surveyed the previous studies about encouraging and resistance factors of ICT utilization in light of the theory of diffusion of innovation and environmental encouraging factors by Ely. Then, the efforts were made to present suggestions to encourage the utilization of ICT in schools.

• The Journal of the Korea Contents Association
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• v.14 no.9
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• pp.589-597
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• 2014

The increasing demand for various mobile telecommunication services calls for more spectrum resource. Considering the scarcity of spectrum resource and the difficulties of development of higher frequency band, the unique way to meet the increasing demand is to maximize the utilization efficiency of the current spectrum resource. Under the circumstances, various spectrum sharing plans have been in recent studies to dissolve the excess spectrum demand. In addition, spectrum efficiency measurement methods become more important to verify the effectiveness of spectrum sharing and estimate the performance of various wireless systems. Our research addresses measurement methods to estimate spectrum utilization efficiency in a rational manner. Based on ITU-R recommendations, various measuring methods for spectrum utilization efficiency are reviewed. Then a queueing based approach is newly presented as alternatives to the current models. By using the proposed model, the spectrum efficiency increment with the adoption of spectrum sharing plans can be estimated more properly.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.749-761
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• 2014

Improving spectrum utilization efficiency is a fundamental goal of dynamic spectrum access technology. The definition of spectrum holes determines how to detect and exploit them. Current definitions of spectrum holes are ineffective in exploiting spatial-temporal spectrum holes. In this paper, a novel definition of spectrum holes is proposed, in which throughput loss indicates the impact of secondary users on primary users. The definition specifies spectrum holes, unifies the impact of secondary users on primary users and is effective exploiting spatial-temporal spectrum holes. Theoretical analysis and numerical simulations show that the new definition proposed in this paper significantly improves the spectrum utilization efficiency.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.1
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• pp.85-93
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• 2011

2010 trend of Web services is Social Network Service. What does Social Network Service are like this? What could really be used? I also take advantage of future can I do? To elicit answers to the question of Social Network Service and the overall status of the root is used in the case Learn about the current utilization plan after the proposed research. The use of practices being applied to Social Network Service, the three theories were derived positive and negative aspects. Research based on more than the utilization of Social Network Service to build a social safety net to take advantage and use of learning aids were divided into suggestions. Utilized for building a social safety net, and when the reported channel to channel, the use of learning aids to learning that one day, one-on learning by applying the proposed total of four kinds of utilization.