• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4C
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• pp.433-441
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• 2003

We propose a new resource reservation scheme called MC-HMRSVP(Mobile clustering based-Hierarchical mobile ReSource reserVation Protcol) that is an extension of HMRSVP[3,4]. MC-HMRSVP always establishes a virtual cluster called Mobile Cluster, which includes its immediately adjacent MA(Mobile Agent) for passive reservation as well as the current MA for active reservation to which MH(Mobile Host) belongs. Our scheme also establishes the MC regardless of intra/inter region movement by GMA(Gateway Mobile Agent) function when a MH moves. To provide a general formulation on analyzing the performance in terms of reservation cost, we also model the resource reservation cost by using a simple recursive equation. Then, we show that our scheme decreases the reservation cost in comparison with the existing HMRSVP extentions.

• The KIPS Transactions:PartC
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• v.11C no.4
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• pp.539-544
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• 2004

This paper presents the implementation of the bluetooth headset and the audio gateway connected to the mobile Phone in the embedded environment. The bluetooth module includes the BC02 processor chip, the BCSP02 firmware and the bluelab software Including bluetooth protocol stack. The above components in the bluetooth module developed at CSR company are used as the development environment. The application program using API functions supported by bluelab is coded by C language and loaded on the flash ROM of the bluetooth module. The cail processing capacity measuring the call setup time and the clearing time between the audio gateway and the headset is considered as the performance parameter of the developed systems. As a call setup and clearing time between the audio gateway and the headset is about 88.8ms, the call processing capacity is about 11 calls per second. Therefore the performance result is satisfied in the aspect of the call processing time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.679-687
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• 2005

A mobile ad-hoc network (MANET) is one consisting of a set of mobile hosts capable of communicating with each other without the assistance of base stations. It is necessary to use bandwidth effectively because MANET has limited bandwidth. In this paper, we propose SMGS (source based multiple gateway selection routing protocol). In SMGS, each node estimates its expected life time (ELT) and if its ELT is larger than that of current gateway it becomes a candidate node. When a source node establishes a path, in each grid the candidate node will take the route request and be a gateway node for the each source node. The node that is expected to stay the longest time in the grid is selected so that we can reduce frequent gateway handoff, packet loss, and handoff delay.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.1
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• pp.24-51
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• 2011

When supporting both voice and TCP in a wireless multihop network, there are two conflicting goals: to protect the VoIP traffic, and to completely utilize the remaining capacity for TCP. We investigate the interaction between these two popular categories of traffic and find that conventional solution approaches, such as enhanced TCP variants, priority queues, bandwidth limitation, and traffic shaping do not always achieve the goals. TCP and VoIP traffic do not easily coexist because of TCP aggressiveness and data burstiness, and the (self-) interference nature of multihop traffic. We found that enhanced TCP variants fail to coexist with VoIP in the wireless multihop scenarios. Surprisingly, even priority schemes, including those built into the MAC such as RTS/CTS or 802.11e generally cannot protect voice, as they do not account for the interference outside communication range. We present VAGP (Voice Adaptive Gateway Pacer) - an adaptive bandwidth control algorithm at the access gateway that dynamically paces wired-to-wireless TCP data flows based on VoIP traffic status. VAGP continuously monitors the quality of VoIP flows at the gateway and controls the bandwidth used by TCP flows before entering the wireless multihop. To also maintain utilization and TCP performance, VAGP employs TCP specific mechanisms that suppress certain retransmissions across the wireless multihop. Compared to previous proposals for improving TCP over wireless multihop, we show that VAGP retains the end-to-end semantics of TCP, does not require modifications of endpoints, and works in a variety of conditions: different TCP variants, multiple flows, and internet delays, different patterns of interference, different multihop topologies, and different traffic patterns.

• Journal of Digital Contents Society
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• v.10 no.1
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• pp.87-96
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• 2009

Digital Broadcast Service is being very popular and the delivery mechanism for digital broadcast content through IP network has progressed constantly, due to the advance of video and audio compression and network technologies. From these trends, in Korea, the commercial IPTV service starts in this year after the law related to IPTV is enacted last year. Since IPTV service, which integrates broadcast and communication services, can give an infrastructure for fusion of communication and interactive multimedia data service, IPTV service is attractive. Recently, by the advent of various wireless connection technologies and the mobile devices of high capability, Mobile IPTV, which has an advantage of not only IPTV but also mobile TV, has gained much interest. In this paper, we review a necessary ingredient for Mobile IPTV in the next generation wired/wireless convergence network environment which consists of heterogeneous wireless access networks. In addition, we propose the scheme for user mobility and service session mobility management using RTSP protocol and introduce the service gateway concept to guarantee the extension of IPTV service platform.

• Journal of Korea Multimedia Society
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• v.11 no.10
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• pp.1385-1391
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• 2008

The network-based IP mobility solution - Proxy MIPv6 provides a mobile node with local mobility support without requiring MIPv6 functionality of the mobile node by using two principle functional entities, LMA (Local Mobility Anchor) and MAG (Mobile Access Gateway) located in a Proxy MIPv6 domain. Yet, in case that a mobile node moves into a mobile network located in the domain, the mobile node can't receive the local mobility support any more because it can't communicate with the MAG. This paper proposes a scheme to support nested network mobility in a Proxy MIPv6 domain by adding MAG functionality to a mobile router in the mobile network and evaluates the performance of the proposed scheme. Performance analysis shows that the proposed scheme can increase the performance of handover delay, signaling costs, and packet loss ratio.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.1999-2007
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• 2010

Proxy Mobile IPv6(PMIPv6) is a network-based mobility management protocol and it does not require mobile node's involving in mobility management. In PMIPv6, the Mobile Access Gateway (MAG) incurs a high signaling cost to update the location of a mobile node to the remote Local Mobility Anchor (LMA) if it moves frequently. It may cause excessive signaling traffic and increase a high traffic load on LMA. Therefore, we propose a new mobility management scheme in proxy mobile IPv6 networks with dynamic paging support. To minimize signaling overhead, in our proposal, the size of the paging area is determined dynamically according the changes of mobility and traffic patterns of the mobile node. An analytic model is applied to determine the optimal size of the paging area. The cost analysis using fluid flow model presented in this paper shows that our proposal can achieve performance superior that of PMIPv6 scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1269-1276
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• 2011

In the Proxy Mobile IPv6 (PMIPv6), the data transmission performance may be degraded when the two communicating hosts are located within the same mobile domain, since all the data packet shall be delivered by way of Local Mobility Anchor (LMA). In this paper we propose an extensional scheme of PMIPv6 using binding query. In the proposed Query-based PMIPv6 (Q-PMIPv6) scheme, the Mobile Access Gateway (NAG) of Correspondent Node (CN) sends a binding query to LMA to obtain the Proxy Care-of-Address of Mobile Node (MN). Since then, CN and MN can communicate with each other by using an optimized data path. For comparison, we performed the numerical analysis and the ns-2 simulations for the proposed Q-PMIPv6 scheme and the existing PMIPv6 and PMIPv6 Localized Routing (PMIPv6-LR). From the results, we can see that the proposed scheme outperforms the existing PMIPv6 and PMIPv6-LR schemes in terms of the signaling control and data delivery costs.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.3
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• pp.3-12
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• 2001

In this course of Internet proliferation, many network-related technologies are examined for possible growth and evolution. The use of Internet-based technologies is private networks has further fuelled the demand for network-based applications. The most promising among the new paradigms is the use of mobile agents. The mobile agent is capable of migrating autonomously form node to node in the network, to perform some computations on behalf of the user. The mobile agent paradigm is attractive alternative to traditional client-server programming for a significant class of network-centric applications. It does however, suffer. from a major drawback namely, the potential for malicious attacks, abuse of resources, pilfering of information, and other security issues. These issues are significantly hampering the acceptance of the mobile-agent paradigm. This paper describes the design of a secure mobile agent gateway 7hat can split and merge the agent code with security policy database on the VPN. This mechanism will promote security in the mobile agent systems.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.6
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• pp.1007-1015
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• 2013

The automatic payment process of mobile phone micropayment system has not checked user's authentication. That is the structural vulnerability of mobile phone micropayment system. The malicious contents provider can cheat users and payment gateway through abusing the structural vulnerability. The payment gateway applies standard payment module after August, 2012 in order to solve the problem. But the standard payment module also has the vulnerability that makes damage of users. So the purpose of this paper is to suggest efficient improvement of standard payment module for user protection.