• The Transactions of the Korea Information Processing Society
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• v.4 no.3
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• pp.685-697
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• 1997

A Viedo-on-Demand(VOD) service is a multimedia service that is realized by the rapid advance of computer and data communication techmologies. Basically, a VOD system is composed of a server and a number fo clients.The server stores and manages a large amount of digital moving picture data. Each slient sends an on-line requwet to the server and receives data for real-time displying. Many researches are performed on a VOD server using hard disks for the permanent video fata storage. However, a hard disk is less reliable and requires more storage cost than a massive storage device. Due to these resasons, a multi-level VOD system is proposed for using teh jukeboxes of optical disks as the permanent video storage,device. In this paper, we prpose the necessary software modules and protocols between the server and its clients for the implementation of the multi-level VOD server.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.162-169
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• 2009

Message Authentication Code (MAC) assures integrity of messages. In Mobile WiMAX, 128-bit Cipher-based MAC (CMAC) is calculated for management messages but only the least significant half is actually used truncating the most significant 64 bits. Naming these unused most significant 64bits Shared Authentication Information (SAI), we suggest that SAI can be applied to protect the network from DDoS attack which exploits idle mode vulnerabilities. Since SAI is the unused half of CMAC, it is as secure as 64bits of CMAC and no additional calculations are needed to obtain it. Moreover, SAI doesn't have to be exchanged through air interface and shared only among MS, BS, and ASN Gateway. With these good properties, SAI can efficiently reduce the overheads of BS and ASN GW under the DDoS attack.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.195-207
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• 2017

Since the smart phone was first introduced, the amount of mobile traffic has increased explosively. The OTT service with personal broadcasting and TV contents and the number of users have been increased in wired network, and there are needs to expand the OTT service to mobile network. In the case of the OTT service in mobile network, the relative small and finite resource may cause the overload of the network due to the massive and high transfer rate. In this paper, we consider a future situation of the OTT user services in the cellular network and propose a novel D2D communication scheme for location-based OTT service, which can reduce and distribute the amount of video traffics. To effectively handle the traffic of OTT services, we propose D2DS and LCS functional blocks in EPC network, which can provide location-based service and D2D management. And, we suggest additional procedures for the location-based service of both content provider and contents receiver UEs with the operation of the proposed D2DS and LCS function block.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6A
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• pp.361-370
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• 2003

This paper attempts to improve the existing architecture of location register for location management in Private Network to Network Interface(PNNI)-based wireless ATM networks. Our approach enhances the hierarchical architecture of location registers based on a PNNI hierarchical architecture, which is referred to as the logical hierarchy architecture of location registers. This paper introduces a logical hierarchy architecture for location registers to reduce the cost of their location management. This logical hierarchy architecture of location registers begins with the lowest level physical location registers that are organized into clusters called logical groups. These logical groups are then represented in higher layers by logical nodes. These logical nodes are again grouped into clusters that are treated as single nodes by the next higher layer. In this way, all location registers are included in this tree-type logical hierarchy architecture. Compared with the existing physical hierarchy architecture of location registers, the analysis results show that the proposed logical hierarchy architecture can reduce the number of databases and thereby the average total location management cost.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.807-810
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• 2005

Constructed network test environment of wireless base for confidentiality guarantee of data and safe transmission that is transmited at Mobile node of Wireless Network environment in this paper. And, progressed research about IKEv2's Multiple-Key Exchange mechanism for efficient security transmission that use IPSec that is built-in to basis to IPv6 of Mobile environment. Have several key to single terminal to solve that is seam at hand off packet transmission process of Mobile Node in Wireless Network and Re-setting for Key and Re-exchange problem that happen frequently and studied technology that move. Key exchange protocol that is used for an experiment loads basically in MIPv6 and used IKEv2 protocol that is used for management and distribution of reliable encryption key between both end. Using network simulator of SSFNet(Scalable Simulation Framework Network Models) in this paper Key exchange delay value of IKEv2's security transmission analyzing comparison Performance measure and studied about problem and improvement way accordingly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.325-338
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• 2012

In this paper, a radio resource allocation scheme for a multi-hop relay transmission in cognitive radio (CR) system is proposed to support the employment of relay nodes in IEEE 802.22 standard for wireless regional area network (WRAN). An optimization problem is formulated to maximize the number of serving secondary users (SUs) under system constraints such as time-divided frame structure for multiplexing and a single resource-unit to every relay-hop. However, due to mathematical complexity, the optimization problem is solved with a sub-optimal manner instead, which takes three steps in the order of user selection, relay/path selection, and frequency selection. In the numerical analysis, this proposed solution is evaluated in terms of service rate denoting as the ratio of the number of serving SUs to the number of service-requesting SUs. Simulation results show the condition of adopting multi-hop relay and the optimum number of relaying hops by comparing with the performance of 1-hop system.

• Journal of Broadcast Engineering
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• v.23 no.2
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• pp.261-273
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• 2018

As progress on image processing, computer vision and display technologies aroused market's interests on generation and consumption of various types of media, interests on UWV media are also increasing. In context of consumption of UWV media, to effectively manage load of servers and resources of end terminal devices and provide user-derived services, technology which enables users to select and consume interested regions of media seems to be needed. Here, this paper proposes a method for description and transmission of spatial relationships among media, which composes UWV, by expanding MPEG-CI and Layout signaling to enable users' selective consumption of UWV media.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.4
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• pp.115-124
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• 2014

Since it costs a lot to build a home network system of new service provider, the entry barrier is quite high. If it would be possible to build a home network system with high performance at a low building cost, it would be quite attractive. If a home network would be built in P2P-SIP(Peer to peer - Session Initiation Protocol) structure, it is possible to decrease server maintenance cost and keep high usability by deconcentrating the traffic concentrated on the server. It is also possible to efficiently manage the location information of terminal, if quorum system based on fuzzy logic would be applied. In this paper we propose the P2P-SIP structure applied of quorum system based on fuzzy logic by which a home network system can be built at low cost. It was possible to know by comparing the structure with existing one that the structure has very good performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4125-4132
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• 2011

The research of image quality estimation standard and the image quality change according to the network traffic load increase at IPTV multicasting service is necessary because the concern of IPTV(Internet Protocol TV) service become active recently. In the research, for finding out the threshold value of network performance elements giving the effect to the image quality according to the network traffic load, we developed S/W to operate the test bed network and make the test scenario through test bed network test and then we expand the test environment scope to the college network and try to measure the image quality change of IPTV multicasting service according to the network traffic load increase at the college network similar to the real IPTV service environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.5
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• pp.1115-1122
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• 2012

VoIP service is steadily growing due to the spread of smartphones, enhanced network, and various VoIP applications. But, VoIP has many security vulnerabilities because it is based on IP network. This paper analyzes the important weight of VoIP security checklists for incident prevention and response using AHP. The results of AHP analysis showed that network security, incident response, and access control were the most important in technical, administrative, physical standpoint. This study proposes factor analysis of VoIP security checklist at first time. By doing this, it will be used helpfully when VoIP service providers establish their own security policies and inspect their VoIP environment according to their security policies.