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김재동,채철주,이재광,Kim, Jae-Dong,Chae, Cheol-Joo,Lee, Jae-Kwang 한국정보통신학회 2007 한국정보통신학회논문지 Vol.11 No.5
최근 기술의 발전으로 인해 인터넷이 정보화사회의 기반이 되는 기술로 발전하고 있는 반면 역기능인 해킹, 바이러스, 정보변조 등과 같은 기술 또한 발전하고 있다. 이러한 역기능에 대응하기 위해 방화벽(Firewall), 침입탐지시스템(Intrusion Detection System) 등과 같은 보안 시스템이 개발되었지만 해킹 사고는 꾸준히 증가하고 있다. 기존의 이러한 수동적인 보안 시스템은 능동적인 시스템으로 발전되었다. 이에 본 논문에서는 IP 역추적 기술을 이용한 능동적 보안 시스템을 제안한다. IP 역추적을 위해 ICMP 형태의 역추적 메시지를 구현하고 지역 네트워크에 배치되는 에이전트와 관리 네트워크에 배치되는 서버 프레임워크를 설계하고, 이러한 능동형 보안 시스템을 기반으로 네트워크 기반의 침입자를 추적하고 고립화하기 위한 보안 메커니즘을 구현한다. There is a tremendous increase in the growth of Internet making people's life easy. The rapid growth in technology has caused misuse of the Internet like cyber Crime. There are several vulnerabilities in current firewall and Intrusion Detection Systems (IDS) of the Network Computing resources. Automatic real time station chase techniques can track the internet invader and reduce the probability of hacking Due to the recent trends the station chase technique has become inevitable. In this paper, we design and implement Active Security system using ICMP Traceback message. In this design no need to modify the router structure and we can deploy this technique in larger network. Our Implementation shows that ICMP Traceback system is safe to deploy and protect data in Internet from hackers and others.
포토리프랙티브 결정 내의 두빔 에너지 결합에서의 Bragg 회절
김재동,김주엽,이연호 成均館大學校 科學技術硏究所 1994 論文集 Vol.45 No.2
In this paper we employ a new method to derive Bragg diffraction from a photorefractive grating without four - wave mixing geometry. In this calculation we assume two - beam energy coupling in a photorefractive crystal to occur due to Bragg diffraction of two incident beams from a photorefractive grating. At a steady - state of two - beam energy coupling we have obtained Bragg diffraction of the incident beams, which corresponds to Bragg diffraction of any incident beam, or a third probe beam. It is shown that our result predicts exactly the same Bragg diffraction as the coupled wave equations of four- wave mixing, and that the diffraction effciency strongly depends on two - beam coupling gain. It is also shown that our result is given by a form much simpler than its counterpart.
2차원 이송-확산 모형을 이용한 취수장 유입 수질 예측
김재동,김지훈,김영도,송창근,서일원 대한상하수도학회 2011 상하수도학회지 Vol.25 No.5
In this study, the influences of pollutant from Dae-po Stream and So-gam Stream located at the downstream of Nak-dong River on the water quality at Mul-geum water intake station were analyzed using RAMS model. Field measurements of velocity by ADCP, and water quality distribution of BOD and TP by water sampling were carried out to present the input and verification data for numerical simulations. The comparison between RAM2 and ADCP measurement, which aimed for the analysis of 2-D velocity distribution around Mul-geum water intake station showed that two results matched well along the spanwise direction. The prediction of pollutant concentration by RAM4 agreed fairly well with the measured data except for the points nearby right banks in the vicinity of tributary pollutant source. Flushing effect by the increase of mainstream discharge in Nak-dong River was analyzed to provide the damage mitigation in preparation for the accidental water pollution. With increasing mainstream discharge, high velocity and increased water quantity induced increasing dilution effect, thereby decreasing the inflow pollutant concentration rapidly.