• Digital Contents
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• no.6 s.157
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• pp.75-83
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• 2006

사람들은 지하철에서 다운로드 받은 모바일게임을 휴대전화로 즐기며, 인터넷에서 방송중인 동영상UCC로 스포츠를 시청하기도 한다. 온라인 속 자신의 또 다른 분신인 아바타 꾸미기에 심혈을 기울이고, 휴대전화 MP3로 좋아하는 음악을 듣는다. 이렇듯 DC는 이제 우리네 일상생활 속에 깊숙이 자리 잡으며 단기간에 국내 중추 산업으로 성장하기에 이르렀다. 이는 수많은 국내 DC 기업들의 도전과 꿈이 있었기에 가능했던 일. 이번 창간 특집 DC vs DC에 서는 때론 경쟁하면서 때론동반자로 DC 산업의 성장을 이끈 업체들을 비교∙분석했다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.279-280
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• 2019

본 논문에서는 모터와 센서를 제어하고 무선통신 까지 지원하는 LEGO MINDSTORMS Education EV3의 다양한 센서를 활용하여 창의융합교육 방식에 대한 연구를 하였다.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.1
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• pp.99-108
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• 2012

In this paper, fatigue tests are conducted for the specimens with longitudinal and transverse attachment under variable amplitude axial loading based on storm model. Considered loadings include repeated single storm, 6 or 8 storms randomly, and storms including calm sea condition while the mean stress and the maximum stress of loadings are changed. The effect of three variables are investigated; root mean square(RMS) value of stress amplitude, mean stress shift and maximum stress, which can characterize storm loading on fatigue life. In addition, experiments including calm sea loading are also carried out to investigate the effect of calm sea state. Test results are evaluated and compared with DNV-CN2005 and Matsuoka's method for the estimation of crack initiation and propagation life. To verify the validity of the criteria, the measured crack initiation lifes are compared with the specific crack length 15mm, which are calculated with beach marks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1092-1099
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• 2017

In this paper, we propose a novel geographical on-demand routing protocol for a mobile ad-hoc network (MANET) that resolves the broadcast storm problem of ad-hoc on-demand distance vector (AODV) routing protocol. The candidates relaying route request (RREQ) packet are geographically restricted by the locations of the destination and a (RREQ sender. Then, the duplicate RREQs, which are generally discarded in the protocols that follow the principle of the AODV, are parsed to avoid redundant RREQ rebroadcasts and to perform passive acknowledgement with respect to a RREQ rebroadcast. The proposed routing protocol is implemented by modifying the source code of the AODV in QualNet. It is shown through QualNet simulations that the proposed routing protocol significantly improves the packet delivery ratio and the latency of the AODV in high-density and heavy traffic network scenarios.

• Journal of Science Education
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• v.42 no.1
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• pp.1-11
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• 2018

STEAM program as integrating Science, Technology, Engineering, Arts, and Mathematics became essential part of secondary education and software education will be a required subject in secondary schools. In this study, we propose the application of the Lego mindstorms robotics programs for the developments of both STEAM and software educational materials. Our program consisting of five hours of classes is made based on the problem solving strategies. According to students' impression obtained after our program had been applied, our program appears to provide students opportunities for conceiving creative thinking and problem solving strategies. It also shows positive results for the application to the software and science educations as well as other extracurricular such as after school programs or programs for gifted students.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.613-618
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• 2012

ICT education guidelines revised in 2005 reinforce computer science elements such as algorithm, data structure, and programming covering all schools. And Ministry of Education emphasizes STEAM education. Most important is that "How instruct them". This means necessity of contents. So this paper suggests learning method of Stack and Queue using LEGO MINDSTORMS NXT. The main purpose is that how stack and queue are used, when robot explore realistic maze. Teaching and learning strategies are algorithm, flowchart, and NXT-G programming. Simple maze has path in left or right, but complex maze has three-way intersection. These are developed by authors. Master robot explores maze and push stack, and then return to entrance using stack. Master robot explores maze and transmits path to slave's queue. And then slave robot drives without exploration. Students can naturally learn principles and applications of them. Through these studies, it can improves ability of logical and creative thinking. Furthermore it can apply to ICT and STEAM education.

• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.363-368
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• 2016

A storage-based VDI (Virtual Desktop Infrastructure) system has the disadvantage of degraded performance when IOs for the VDI system are concentrated on the storage. The performance of the VDI system decreases rapidly especially, in case of the boot storm wherein all virtual desktops boot simultaneously. In this paper, we propose a main memory-based virtual desktop system managing virtual desktop images on main memory to solve the performance degradation problem including the boot storm. Performance of the main memory-based VDI system is improved by storing the virtual desktop image on the main memory. Also, the virtual desktop images with large size can be stored in the main memory using deduplication technology. Implementation of the proposed VDI system indicated that it has 4 times performance benefit than the storage-based VDI system in case of the boot storm.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.409-418
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• 2005

Magnetospheric substorms occur frequently during magnetic storms, suggesting that the two phenomena are closely associated. We can investigate the relation between magnetospheric substorms and magnetic storms by examining the correlation between AE and Dst indices. For this purpose, we calculated the monthly cumulative AU, $\mid{AL}\mid$ and $\mid{Dst}\mid$ indices. The correlation coefficient between the monthly cumulative $\mid{AL}\mid$ and $\mid{Dst}\mid$ index is found to be 0.60, while that between monthly cumulative AU and $\mid{Dst}\mid$ index is 0.28. This result indicates that substorms seem to contribute to the development of magnetic storms. On the other hand, it has been reported that the interplanetary electric field associated with southward IMF intensifies the magnetospheric convection, which injects charged particles into the inner magnetosphere, thus developing the ring current. To evaluate the contribution of the interplanetary electric field to the development of the storm time ring current belt, we compared the monthly cumulative interplanetary electric field and the monthly cumulative Dst index. The correlation coefficient between the two cumulative indices is 0.83 for southward IMP and 0.39 for northward IMF. It indicates that magnetospheric convection induced by southward IMF is also important in developing magnetic storms. Therefore, both magnetospheric substorm and enhanced magnetospheric convection seem to contribute to the buildup of magnetic storm.

• Publications of The Korean Astronomical Society
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• v.15 no.spc2
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• pp.53-56
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• 2000

We investigate the critical issue on how the BBF (bursty bulk flow) is related to the substorm current wedge formation. Observationally, after analysing data sets from Geotail spacecraft at near tail and many ground magnetic observatories for 9 months period of 1996, we find three BBF events that clearly occurred at the center of the wedge with region I type FAC (field-aligned current), and two other BBF events that were seen outside the wedge sector. Theoretically, we suggest that the substorm current wedge generation by BBF is most likely when the h' VB contribution is dominant in the well-known MHD $J_{II}$ expression (Vasyliunaus, 1984) or when the divergence of the cross-tail current carried by the particle's gradient/curvature drift is predominantly sufficient at the moment of the BBF arrival at near tail.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.298-299
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• 2011

최근 스마트폰의 수요증가와 대중화로 인하여 스마트폰을 활용한 다양한 연구가 진행 되고 있다. 이중 항만 물류 하역 시스템에도 스마트폰과 관련된 관심이 높아져 스마트폰을 이용한 다양한 서비스를 지원하고 그에 따른 다양한 프로젝트도 진행 중에 있다. 항만 물류 시스템은 중앙관리실에서 자동화된 시스템으로 관리되고 있으며 이중 하역장비 운용은 관리자가 중앙 관리실에서 원격으로 제어 하고 있다. 이는 관리자가 자리에 위치해 있어야만 관리가 가능하기 때문에 관리자의 이동성을 보장 하지 못한다. 따라서 본 논문에서는 스마트폰으로 하역장비를 원격제어 할 수 있도록 하여 관리자의 이동성을 보장하고 보다 효율적인 작업이 가능하도록 설계하였다. 또한 이를 테스트 해보기 위해 항만 하역장비 원격제어 시스템을 Lego_NXT를 이용하여 프로토타입으로 제시한다.