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이대영,민경욱,LEE DAE-YOUNG,MIN KYOUNG WOOK 한국천문학회 2000 天文學論叢 Vol.15 No.suppl2
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.
Observation of long-term disappearance and reappearance of the outer radiation belt
이대영,신대규,김경찬,김진희,조정희,박미영,황정아,이용희,김경호,Lee, Dae-Young,Shin, Dae-Kyu,Kim, Kyung-Chan,Kim, Jin-Hee,Cho, Jung-Hee,Park, Mi Young,Angelopoulos, Vassilis,Hwang, Junga,Lee, Yonghee,Kim, Thomas 한국천문학회 2012 天文學會報 Vol.37 No.2
In this study we have used the data of various instruments onboard the THEMIS spacecraft to study the characteristics of the outer radiation belt during the ascending phase of solar cycle 24. The most astonishing result is that we discovered four long-term (a month or so) periods during which the belt has nearly disappeared. The first disappearance started late 2008, followed by reappearance in ~a month, and three more similar events repeated until early 2010 when the belt has reappeared. This is well revealed at 719 keV electrons, which is the currently available uppermost energy channel from the THEMIS SST observation, but also seen at even lower energies. Overall consistent features were confirmed using the NOAA-POES observations. The vanished belt periods are associated with extremely weak solar wind conditions, low geomagnetic disturbances (in terms of Kp and AE/AL), greatly suppressed wave (ULF and chorus) activities, greatly reduced storm and substorm activities (little source particle supply), and expanded plasmapause locations. The direct observations of such events shed light on the fundamental question of the origin of the radiation belt, which is the main focus of our presentation.
분산 네트워크 환경하에서 암호화 된 사용자 인증 모듈을 적용한 데이터베이스 보안 시스템
이대영,김옥환,Lee Dae-Young,Kim Ok-Hwan 한국정보통신학회 2006 한국정보통신학회논문지 Vol.10 No.2
분산 컴퓨터 네트워크는 단일 시스템의 동작 정지로 인한 전체 시스템에 미치는 영향을 적 게 함으로써 신뢰도를 높일 수 있고, 한 개의 대형 시스템을 활용하는 것 보다 저렴한 비용으로 보다 나은 성능을 얻을 수 있는 장점이 있다. 또한 시스템이 확장 및 재구성이 용이하다[1]. 그러나, 분산 컴퓨팅 환경에서 네트워크를 통한 데이터의 공유는 실생활이 되고 있는 반면 네트워크 환경에서 데이터의 무결성과 보안에 대한 위험성은 증가하고 있다[2],[3]. 따라서 본 논문에서는 운영적 요소와 기술적 요소에 대한 분석을 통해 이러한 요소들을 결합시키기 위한 네트워크 암호화 데이터베이스 보안시스템 모델을 제시한다. 제시한 모델에 운영적 요소와 기술적 요소를 체계적으로 결합시킨다면 분산 컴퓨팅 환경에서 허가받지 않은 사용자로부터 데이터를 안전하게 보호할 암호화 데이터베이스 보안 시스템을 구축할 수 있을 것이다. This paper describes access control, user authentication, and User Security and Encryption technology for the construction of database security system from network users. We propose model of network encrypted database security system for combining these elements through the analysis of operational and technological elements. Systematic combination of operational and technological elements with proposed model can construct encrypted database security system secured from unauthorized users in distributed computing environment.
MANET 환경 하에서 멤버 노드간의 협력에 의해 분산된 인증서를 이용한 인증서비스에 관한 연구
이대영,송상훈,배상현,Lee, Dae-Young,Song, Sang-Hoon,Bae, Sang-Hyun 한국정보통신학회 2007 한국정보통신학회논문지 Vol.11 No.1
Ad-Hoc 네트워크 기술이 미래의 이동 인터넷 기술로서 이동통신망(Mobile Network) 뿐만 아니라 공중무선랜망(WPAN) 그리고 유비쿼터스 망 등에 광범위하게 활용되기 위해서는 개선 및 보완되어야 할 기술적인 문제들이 많다. 특히, 최근 네트워크 보안의 허점을 이용한 보안상 공격이 급증하고 있는 상황에 반하여 Ad-Hoc 라우팅 프로토콜 연구 대부분은 보안 위협 요소를 배제하고 안전한 환경을 가정한 채 수행되고 있다. 또한 Ad-Hoc 네트워크가 무선 매체 특성상 더욱 많은 보안상 위협에 노출되기 쉽고 유선에서 사용되던 보안 메커니즘을 그대로 적용되는 것이 부적합함을 고려할 때 Ad-Hoc 보안에 관한 연구는 더욱 활발히 이루어져야 할 것이다. 따라서 본 논문에서는 Ad-Hoc 네트워크의 특성을 고려하여 중앙 집중적인 인증기관이나 키 분배센터에 의존하지 않고 클러스터를 구성하고 있는 멤버 노드들 간의 협력적이고, 분산된 인증서를 이용한 인증 서비스를 제공할 수 있는 모델을 제안한다. 아울러 시뮬레이션을 통해 제안한 모델의 확장성과, 견고성을 평가해 본다. Ad-Hoc network technology is a mobile internet technology of the future that will be used widely not only in Mobile Network but also in Wireless Personal Area Network (WPAN) and Ubiquitous Network For this to occur, distributed routing protocol design, loop prevention for link information reduction in overhead for control messages and route restoration algorithm must be improved or complemented. Security techniques that can guarantee safe com-munication between Ad-Hot nodes net also be provided. This study proposes and evaluates a new authentication mechanism for MANET. The mechanism segregates the roles of certification authority to keep with the dynamic mobility of nodes and handle rapid and random topological changes with minimal over-head. That is, this model is characterized by its high expandability that allows the network to perform authentication service without the influence of joining and leaving nodes. The efficiency and security of this concept was evaluated through simulation.
이대영,박윤철,오명도,김용열,장승찬,Lee Dae-Yeong,Park Yun-Cheol,O Myeong-Do,Kim Yong-Yeol,Jang Seung-Chan 대한설비공학회 2006 설비저널 Vol.35 No.7
우리나라 지역냉난방 사업의 특성을 분석하여 향후 집단에너지 사업의 발전 방향을 제시한다.
이대영,Sabina Shrestha,Woo Duck Seo,Min-Ho Lee,Tae-Sook Jeong,Jun Hyun Cho,You Chun Song,Hang Won Kang,노영덕,백남인 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.4
Grains of sugary rice were extracted with 80% aqueous methanol, and the concentrated extracts were successively partitioned using ethyl acetate, n-butanol, and water. From the n-butanol fractions, four flavonoid glycosides were isolated through repeated silica gel, octadecyl silica gel, and Sephadex LH-20 column chromatographies. Based on the nuclear magnetic resonance, mass spectrometry, and infrared spectroscopic data, the chemical structures of the compounds were determined to be taxifolin-7-O-b-d-glucopyranoside (1), hyperin (2), isoquercitrin (3), and quercetin gentiobioside (4). These compounds were isolated from the grains of sugary rice for the first time. All isolated compounds were tested for antioxidant activity and lowdensity lipoprotein (LDL)-antioxidative activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and LDL assays. Compound 1exhibited a strong scavenging effect on DPPH, with a 50% inhibition concentration (IC50) value of 8.1 lM, and also inhibited LDL oxidation with an IC50 value of 40.0 – 20 lM. A simple and efficient high-performance liquid chromatography/diode array detection method for the simultaneous determination of the four bioactive flavonoids (1–4) has been developed and applied to their content determination in the sugary rice. The grains were extracted by 80% methanol, and the contents of 1, 2, 3, and 4 were determined to be 1.12 – 0.045, 0.65 – 0.011, 0.68 – 0.032, and 0.89 – 0.021mg/g, respectively.