• 천문학회보
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• 제34권1호
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• pp.116.1-116.1
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• 2009

• 천문학회보
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• 제35권1호
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• pp.43.1-43.1
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• 2010

We have carried out 43-GHz VLBI test observations of the Korean VLBI Network (KVN), which has obtained the first fringes at 22/43-GHz in 2009 (a talk by Sohn, Bong Won). In collaboration with VERA (VLBI Exploration of Radio Astrometry) in Japan, we have observed Active Galactic Nuclei (AGNs) and Orion-KL at 43GHz on 22nd and 23rd December, 2009, in order to evaluate the baseline- and image-sensitivity of KVN and KVN+VERA. In this talk we report the preliminary results of the VLBI test observations of the Korean VLBI Network at 43GHz.

• International Journal of Computer Science & Network Security
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• 제23권9호
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• pp.111-119
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• 2023

Mobile Ad-hoc Network (MANET) is an infrastructure-less network that can configure itself without any centralized management. The topology of MANET changes dynamically which makes it open for new nodes to join it easily. The openness area of MANET makes it very vulnerable to different types of attacks. One of the most dangerous attacks is the Resource Consumption Attack (RCA). In this type of attack, the attacker consumes the normal node energy by flooding it with bogus packets. Routing in MANET is susceptible to RCA and this is a crucial issue that deserves to be studied and solved. Therefore, the main objective of this paper is to study the impact of RCA on two routing protocols namely, Ad hoc On-Demand Distance Vector (AODV) and Dynamic Source Routing (DSR); as a try to find the most resistant routing protocol to such attack. The contribution of this paper is a new RCA model (RCAM) which applies RCA on the two chosen routing protocols using the NS-2 simulator.

• International Journal of Computer Science & Network Security
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• 제23권7호
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• pp.131-140
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• 2023

Network security situational awareness systems helps in better managing the security concerns of a network, by monitoring for any anomalies in the network connections and recommending remedial actions upon detecting an attack. An Intrusion Detection System helps in identifying the security concerns of a network, by monitoring for any anomalies in the network connections. We have proposed a CRF based IDS system using genetic search feature selection algorithm for network security situational awareness to detect any anomalies in the network. The conditional random fields being discriminative models are capable of directly modeling the conditional probabilities rather than joint probabilities there by achieving better classification accuracy. The genetic search feature selection algorithm is capable of identifying the optimal subset among the features based on the best population of features associated with the target class. The proposed system, when trained and tested on the bench mark NSL-KDD dataset exhibited higher accuracy in identifying an attack and also classifying the attack category.

• 천문학논총
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• 제20권1호
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• pp.63-71
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• 2005

e-VLBI was invented to enhance the efficiency of VLBI (Very-Long-Baseline Interferometry) system by transmitting the data via high speed network. Korean VLBI Network (KVN) has a plan to construct e-VLBI system named e-KVN. High speed backbone network and efficient network model are essential to implement successful e-VLBI system. This paper introduces a network model based on PC cluster technology. The present status of high speed backbone network in Korea is overviewed. We suggest that the network link via Korea Advanced Research Network (KOREN) is one of feasible way for e-KVN. We also describe the principles of e-VLBI and protocol for network transmission such as VSI-E (VLBI Standard Interface - Electronic), RTP (Real-Time Transport Protocol) and RTCP (Real-Time Transport Control protocol).

• 천문학회보
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• 제34권1호
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• pp.115.2-115.2
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• 2009

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권11호
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• pp.2764-2783
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• 2012

Network virtualization supports future Internet environments and cloud computing. Virtualization can mitigate many hardware restrictions and provide variable network topologies to support variable cloud services. Owing to several advantages such as low cost, high flexibility, and better manageability, virtualization has been widely adopted for use in network virtualization platforms. Among the many issues related to cloud computing, to achieve a suitable cloud service quality we specifically focus on network and performance isolation schemes, which ensure the integrity and QoS of each virtual cloud network. In this study, we suggest a virtual network platform that uses Xen-based virtualization, and implement multiple virtualized networks to provide variable cloud services on a physical network. In addition, we describe the isolation of virtual networks by assigning a different virtualized network ID (VLAN ID) to each network to ensure the integrity of the service contents. We also provide a method for efficiently isolating the performance of each virtual network in terms of network bandwidth. Our performance isolation method supports multiple virtual networks with different levels of service quality.

• 한국과학교육학회지
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• 제40권6호
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• pp.631-648
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• 2020

이 연구는 과학학습에서 무엇에 주목해야 하느냐는 고민의 연장선에서 이종네트워크로서의 과학학습의 의미에 대해 논의하는 것을 목적으로 수행되었다. 연구 결과, 이론적 논의를 통해 이종네트워크가 갖는 특징을 이종적 구성, 관계에 의한 존재, 번역에 의한 구축과 변화라는 세 가지 측면에서 살펴볼 수 있었다. 그리고 과학학습 역시 이러한 이종네트워크의 특성이 있음을 논의하였다. 더불어서, 이종네트워크로서 과학학습은 우리에게 사물의 격상, 결절된 이종네트워크로서의 개념, '설다'와 '익다'의 너나들이라는 이종네트워크의 구축과 확장으로서의 학습 과정에 주목할 것을 요청하고 있음을 논의하였다. 끝으로 이를 바탕으로 과학학습과 관련하여 몇 가지 제언을 하였다.

• 천문학회보
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• 제35권2호
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• pp.59.1-59.1
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• 2010

We have carried out VLBI test observations of the Korean VLBI Network (KVN) at 22/43-GHz in collaboration with Japanese VLBI Exploration of Radio Astrometry (VERA). In order to evaluate the VLBI system of KVN, we have observed several sources using KVN+VERA. They consist of Active Galactic Nuclei (AGNs), which are expected to be compact and to have very well-known structures at spatial resolutions of 50-250 Mega-wavelengths, and Galactic star-forming regions and late-type stars, which have bright H2O and SiO maser emission regions. We have investigated baseline and imaging sensitivities of KVN+VERA. In this talk we report the preliminary results.

• Journal of Information Science Theory and Practice
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• 제10권spc호
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• pp.154-163
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• 2022

The purpose of this paper is to illuminate the role and importance of National Research & Education Network (NREN) in the national research and education field and to establish the future strategy of KREONET in Korea. To this end, we first carefully analyze the footsteps of NREN in major overseas countries, KREONET achievements, and future demand for KREONET. The history of NREN's development is divided into the 2000s, 2010s, and present by era, and classified into network infrastructure, network service, and next-generation network technology by subject. KREONET achievements are divided into advanced research support, network backbone and operation, and network service. Future demand analysis of users who use KREONET was conducted through Korea Research International Incorporation, a survey company. This paper presents the future development strategy of KREONET by analyzing KREONET achievements and future demand.