• Journal of Astronomy and Space Sciences
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• v.25 no.2
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• pp.139-148
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• 2008

It has been known that high-speed solar wind streams associated with coronal holes lead to quasi-periodic substorms that occur approximately every $2{\sim}4$ hours. In this paper we examined 222 repetitive substorms that occurred during high-speed stream periods in July through December in 2003 to quantitatively determine a range of energy input from the solar wind into the magnetosphere between two consecutive substorms. For this study, we have used the Akasofu ${\varepsilon}$-parameter to time-integrate it for the interval between two consecutive substorms, and have applied this method to the 222 substorms. We find that the average amount of solar wind input energy between two adjacent substorms is $1.28{\times}10^{14}J$ and about 85% out of the 222 substorms occur after an energy input of $2{\times}10^{13}{\sim}2.3{\times}10^{14}J$. Based on these results, we suggest that it is not practical to predict when a sub storm will occur after a previous one occurs purely based on the solar wind-magnetosphere energy coupling. We provide discussion on several possible factors that may affect determining substorm onset times during high-speed streams.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.451-466
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• 2009

While substorms are known to generally occur under southward IMF conditions, they can sometimes occur even under northward IMF conditions. In this paper, we studied the substorms that occurred in May, 2000 to 2002 to examine some statistical characteristics of the IMF and solar wind associated with northward IMF substorms. We focused on the cases where two or more substorms occurred successively under northward IMF conditions. Also, by checking Sym-H index associated with each of the substorms we determined whether or not there is any association of such northward IMF substorm occurrence with storm times. We also examined statistical properties at geosynchronous altitude in terms of magnetic field dipolarization and energetic particle injection. The following results were obtained. (i) Most of the northward IMF substorms occurred under average solar wind conditions. The majority of them occurred within 2 hrs duration of northward IMF Bz state, but there are also a nonnegligible number of substorms that occurred after a longer duraiton of northward IMF Bz state. (ii) While most of the substorms occurred as isolated from a magnetic storm time, those that occurred in a magnetic storm time show a higher average value of IMF and solar wind than that for the isolated substorms. (iii) About 55% of the substorms were associated with the IMF clock angle that can possibly allow dayside reconnection, and the other 45% were associated with more or less pure northward IMF conditions. Therefore, for the latter cases, the energy input from the solar wind into the magnetosphere should be made by other way than the dayside reconnection. (iv) For most of the substorms, the magnetic field dipolarizations and energetic particle injections at geosynchronous altitude were identified to be generally weak. But, several events indicated strong magnetic field dipolarizations and energetic particle injections.

• Journal of the Korea Society of Computer and Information
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• v.29 no.7
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• pp.1-9
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• 2024

In this paper, we propose BRAIDS, a boot storm mitigation plan consisting of an AI-based VDI usage prediction system and a virtual machine boot scheduler system, to alleviate boot storms and improve service stability. Virtual Desktop Infrastructure (VDI) is an important technology for improving an organization's work productivity and increasing IT infrastructure efficiency. Boot storms that occur when multiple virtual desktops boot simultaneously cause poor performance and increased latency. Using the xgboost algorithm, existing VDI usage data is used to predict future VDI usage. In addition, it receives the predicted usage as input, defines a boot storm considering the hardware specifications of the VDI server and virtual machine, and provides a schedule to sequentially boot virtual machines to alleviate boot storms. Through the case study, the VDI usage prediction model showed high prediction accuracy and performance improvement, and it was confirmed that the boot storm phenomenon in the virtual desktop environment can be alleviated and IT infrastructure can be utilized efficiently through the virtual machine boot scheduler.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.561-564
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• 2018

최근 빠르게 발생하는 빅데이터 스트림이 다양한 분야에서 활용되고 있다. 이러한 빅데이터 전체를 수집하고 처리하는 것은 매우 비경제적이므로, 데이터 스트림 중 필요한 데이터를 걸러내는 필터링 과정이 필요하다. 본 논문에서는 아파치 스톰(Apache Storm)을 사용하여 데이터 스트림의 질의 필터링 시스템을 구축한다. 스톰은 대용량 데이터 스트림을 처리하기 위한 실시간 분산 병렬 처리 프레임워크이다. 하지만, 스톰은 입력 데이터 구조나 알고리즘 변경 시, 코드의 수정과 재배포, 재시작 등이 필요하다. 따라서, 본 논문에서는 이 같은 문제를 해결하기 위해 아파치 카프카(Apache Kafka)를 사용하여 데이터 수집 모듈과 스톰의 처리 모듈을 분리함으로써 시스템의 가용성을 크게 높인다. 또한, 시스템을 웹 기반 클라이언트-서버 모델로 구현하여 사용자가 언제 어디에서든 질의 필터링 시스템을 사용할 수 있게 하며, 웹 클라이언트를 통해 입력한 질의를 자동적 분석하는 쿼리 파서를 구현하여 별도의 프로그램의 수정 없이 질의 필터링을 적용할 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.157-160
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• 2014

본 논문에서는 최근 주목받고 있는 임베디드 시스템 개발을 위한 소프트웨어 교육의 필요성을 살펴보고 이를 위해 레고 마인드스톰 EV3 교구를 활용한 학습프로그램을 개발하여 제안하고자 한다.

• 베이커리
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• no.8 s.457
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• pp.96-98
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• 2006

한영기업 오븐은 국산 오븐을 대표하는 업계 베스트셀러다. 특히 오븐시장의 새로운 강자로 떠오르고 있는 컨벡션 오븐은 순수 국내 기술력으로 완성해 업계에서 경쟁력 있는 제품으로 자리매김했다. 국내산 오븐의 막강 자존심 스톰 컨벡션 오븐을 소개한다.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.80-80
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• 2003

서브스톰이 진행될 때 극지방의 지자기 교란은 대류 제트 전류와 서브스톰 전류 쐐기로 구성되는 오로라 제트 전류에 기인한다. 이들은 전기장 강화를 뜻하는 AU 지수와 전기 전도도 강화를 뜻하는 AL 지수로 나타낼 수 있다. 이들 AU, AL 지수와 자기폭풍의 정도를 나타내는 Dst 지수와의 상관관계를 구해봄으로써 서브스톰이 자기폭풍의 형성에 어떻게 기여하는지 조사하였다. 이를 위하여 월별 누적 AU, 누적 │AL│ 값을 구한 뒤 월별 누적 Dst 와의 상관관계를 구하였다. 한편 IMF(Interplanetary Magnetic Field)의 남쪽 자기장 성분으로부터 지구 자기장 내에 강력한 전기장이 형성되어 자기폭풍을 형성한다는 견해가 있다. 전기장 E=V(태양풍 속도)$\times$Bs(IMF의 남쪽 자기장 성분)으로 나타낼 수 있으므로 이로부터 구한 월별 누적 전기장과 누적 Dst 값을 비교해 봄으로써 자기권 대류가 자기폭풍 형성에 어느 정도 기여하는지 조사하였다. 본 연구를 위하여 1966년부터 1987년까지 20년간의 AE(AU, AL) 지수를 이용하였으며 IMF 자료는 ACE 위성이 제공하는 행성간 자기장 자료로 1997년부터 2002년까지의 자료를 이용하였다. 본 연구의 결과는 현재 논쟁이 되고 있는 storm-substorm의 인과관계를 보다 잘 규명할 것으로 기대된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.435-436
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• 2015

In order to analyze and maximize efficiency of advertise, business put more importance on SNS. Especially, keyword extraction analyses based on Hadoop receive attention. The existing keyword extraction analyses have mostly MapReduce processes. Due to that, it causes problems data base would not update in real time like SNS system. In this study, we indicate limitations of the existing model and suggest new model using Storm technique to analyze data in real time.

• Journal of Internet Computing and Services
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• v.11 no.4
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• pp.159-173
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• 2010

It is difficult for us to teach the introduction course of programming to beginners just starting their college life. What is particularly hard to do is to provide them with learning motivation so that the freshmen can be easily and rapidly adapted to programming work and to enhance their will to learn. In this paper, we suggest a method to apply LEGO Mindstorms robot to the introduction course of programming in purpose to allow programming beginners to be motivated and have higher will to learn so that they can receive programming education easily and joyfully. This paper attempts to find reasonable methods for improvement which can help programming beginners to be motivated and encouraged to learn in the course of C programming education and can facilitate learning effects as well, and conducts education using LEGO Mindstorms robot as a way to solve problems like students' low interest or will to learn. According to the result of providing the freshmen with the introduction course of C programming to which the suggested method was applied, it was found that their academic achievement in programming education enhanced through their increased motivation and will to learn programming. This result shows that students' interest, motivation, and will to learn the subject are statistically significant improvement through the course that employs LEGO Mindstorms robot.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1559-1562
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• 2012

레고 마인드스톰 NXT는 다른 로봇 키드에 비해서 조작이 간편하며, 고차원적인 로봇 행위를 제어하기 위해 펌웨어인 leJOS를 지원하며, 블루투스를 이용한 원격 제어가 가능하다. 그러나 leJOS는 외부 파일을 제어하거나 센서 하드웨어가 정상 동작하지 않는 등의 몇 가지 문제점이 발견되었다. 본 논문에서는 leJOS가 갖는 이러한 일련의 문제점을 살펴보고, 이에 대한 해결책을 제시한다.