• Convergence Security Journal
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• v.19 no.4
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• pp.87-96
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• 2019

Recently, with the rapid development of video equipment and technology, tremendous video information is produced and utilized in military domain to acquire battlefield information or for effective command control. Note that the video playback devices currently used in the military domain ranges from low-performance tactical multi-functional terminals (TMFT) to high-performance video servers and the networks where the video information is transmitted also range from the low speed tactical information and communication network (TICN) to ultra-high speed defense broadband converged networks such as M-BcN. Therefore, there is a need for an efficient streaming technique that can efficiently transmit defense video information in heterogeneous communication equipment and network environments. To solve the problem, this paper proposes a Scalable Video Coding (SVC) and balanced selection algorithm based Peer-to-Peer (P2P) streaming technique and the feasibility of the proposed technique is verified by simulations. The simulation results based on our BitTorrent simulator show that the proposed balanced selection scheme outperforms the sequential or rarest selection algorithm.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.8
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• pp.12-20
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• 1998

All-optical networks(AON) are emerging as the next generation broadband networks for wide-area and local-area networks. Many optical switch architectures are currently proposed to realize AON. Specially, optical switches using WDM have a lot of advantages in point of the optical transparency and network topology for B-ISDN services in AON. In this paper, two kinds of Knockout Optical Switching Architectures(KOSA) are proposed for high speed optical ATM networks. We use WDM technologies for them to operate in all-optical area and they are called Architecture-Ⅰ, Architecture-Ⅱ respectively. Each one represents different characteristics according to the number of components and the kind of components, which make KOSA have different performance and system complextity. In order to verify and to compare the performance, these architectures were analyzed and simulated in terms of cell loss ratio, system complexity and buffering speed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.197-200
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• 2013

Internet phone, communication cost and easy-to-use low-cost compared to the PSTN is a mobile phone of a conventional, and use of the Internet phone is spreading. Construction as part of the broadband convergence network(BCN), Internet service provider(KT, SKT, LG) has converted to Internet phone telephone network to all government agencies. In addition, members of the public also have an Internet phone service that you are using. In this paper, we analyze the hacking attack on IP-PBX in the IETF SIP-based that are used in Internet telephony, to the study. The test bed is constructed in the same way as the Internet telephone system to perform studies carried hacking attacks on IP-PBX, analyze the results and to extract evidence forensics. When used in crime by hacking the Internet telephone, we propose a method which can be used as evidence in forensic having legal effect.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.21-28
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• 2011

The femtocell is a miniaturized Base Station (BS) with low-cost and low-power using general broadband access network as backhaul. It is expected not only to improve indoor coverage but also to reduce a service charge. However, in IEEE 802,16e femtocells, when the Mobile Station (MS) scans neighbor BSs for handover, it takes a long time due to too many number of femto BSs. Also the size of the neighbor advertisement message that will be periodically sent by a serving BS is increased as the number of target femto BSs for scanning increases. In this paper, we proposed an efficient femtocell scanning scheme, using a triangulation mechanism and a femto BS monitoring scheme to reduce the number of scanning operations and the size of the neighbor advertisement messages. The proposed scheme can avoid wasting air resources and reduce scanning overheads by minimal scanning operation. The simulation results showed that the proposed scheme could improve scanning performance and avoid wasting air resources, compared with the conventional scheme of the IEEE 802.16e system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.4
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• pp.1256-1275
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• 2014

As one of the new self-organizing and self-configuration broadband networks, wireless mesh networks are being increasingly attractive. In order to solve the load balancing problem in wireless mesh networks, this paper proposes a novel multi-path routing algorithm based on clustering (Cluster_MMesh) for wireless mesh networks. In the clustering stage, on the basis of the maximum connectivity clustering algorithm and k-hop clustering algorithm, according to the idea of maximum connectivity, a new concept of node connectivity degree is proposed in this paper, which can make the selection of cluster head more simple and reasonable. While clustering, the node which has less expected load in the candidate border gateway node set will be selected as the border gateway node. In the multi-path routing establishment stage, we use the intra-clustering multi-path routing algorithm and inter-clustering multi-path routing algorithm to establish multi-path routing from the source node to the destination node. At last, in the traffic allocation stage, we will use the virtual disjoint multi-path model (Vdmp) to allocate the network traffic. Simulation results show that the Cluster_MMesh routing algorithm can help increase the packet delivery rate, reduce the average end to end delay, and improve the network performance.

• Journal of KIISE:Information Networking
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• v.32 no.6
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• pp.745-752
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• 2005

BGP is a unique routing protocol in broadband internet. It chooses routing paths considering internet hierarchy and local policies. As BGP routers selectively bypass routing information to a subset of neighboring BGP routers, connectivity by way of a series of links between source and destination nodes does not mean reachability of routing information of the two. In emergency when BGP routers or links over wide range are not available, BGP routers have to use links that are not normally used to keep reachability. This paper listed out the requirements for BGP backup routing and proposed a routing solution that hides most demerits in currently published ones. The proposed backup operates in three tiers according to network damage. Under this rule, BGP routers use tier-0 routing paths at normal. If networks are impaired, they choose tier-1 paths. If networks are seriously damaged, tier-2 paths are allowed to use. Also this paper proves that the proposed backup guarantees stability and safeness. As results, the proposed backup is very adaptive to light network damages as well as serious ones and provides strong routing reachability at all times.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.54.2-54.2
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• 2016

Korea Microlensing Telescope Network (KMTNet) is the first optical survey system of its kind in a way that three KMTNet observatories are longitudinally well-separated, and thus have the benefit of 24-hour continuous monitoring of the southern sky. The wide-field and round-the-clock operation capabilities of this network facility are ideal for survey and the physical characterization of small Solar System bodies. We obtain their orbits, absolute magnitudes (H), three dimensional shape models, spin periods and spin states, activity levels based on the time-series broadband photometry. Their approximate surface mineralogy is also identified using colors and band slopes. The automated observation scheduler, the data pipeline, the dedicated computing facility, related research activity and the team members are collectively called 'DEEP-South' (DEep Ecliptic Patrol of Southern sky). DEEP-South observation is being made during the off-season for exoplanet search, yet part of the telescope time is shared in the period between when the Galactic bulge rises early in the morning and sets early in the evening. We present here the observation mode, strategy, software, test runs, early results, and the future plan of DEEP-South.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.8-19
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• 2010

In this paper, we propose the NCP (Network Control Platform)-based defense mechanism against DDoS (Distributed Denial of Service) attacks in order to guarantee the transmission of normal traffic and prevent the flood of abnormal traffic. We also define defense modules, the threshold and packet drop-rate used for the response against DDoS attacks. NCP analyzes whether DDoS attacks are occurred or not based on the flow and queue information collected from SR (Source Router) and VR (Victim Router). Attack packets are dopped according to drop rate decided from NCP. The performance is simulated using OPNET and evaluated in terms of the queue size of both SR and VR, the transmitted volumes of legitimate and attack packets at SR.

• The Transactions of the Korea Information Processing Society
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• v.4 no.8
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• pp.2080-2091
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• 1997

It is generally recognized that Video On Demand (VOD) service will become a promising interactive service in the emerging broadband integrated services digital networks. A centralized VOD system, all programs are stored in a single VOD server which is linked to each user via exchanges, is applicable when a small number of users enjoys the VOD service. However, in case of large service penetration, it is very important to solve the problems of bandwidth and load concentrating in the central video server(CVS) and program transmission network. In this paper, the architecture of the video distribution service network is studied, then a traffic characteristics and models for VOD system are established, and proposed program allocation method to video servers. For this purpose, we present an analysis of program storage amount in each LVS(Local Video Server), transmission traffic volume between LVSs, and link traffic volume between CVS and LVSs, according to changing the related factors such as demand, the number of LVS, vision probability, etc. A method for finding out storage capacity in LVSs is also presented on the basis of the tradeoffs among program storage cost, link traffic cost, and transmission cost.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.8
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• pp.1074-1081
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• 2021

It has recently been noticed that the headway of unlicensed wireless technology is necessary as user's demands of wireless tech increase and the development of high-speed data service by using low-power short-range wireless network is needed. Hence, it is inevitable to study sharing and coexistence for broadband spectrum of diverse unlicensed application with wide bandwidth. In this paper, an interference examination between unlicensed WiFi (Wireless Fidelity) in the 6GHz and OB (Outside Broadcasting) system which is an incumbent service in the same frequency band was conducted and it suggests separation distance for the coexistence. Thus, MCL (Minimum Coupling Loss) and MC (Monte Carlo) methods were used to set up interference scenarios for the interference analysis and compute the separation distance between two systems according to the same frequency band and frequency separation.