• Journal of KIISE:Information Networking
• /
• v.27 no.2
• /
• pp.219-225
• /
• 2000

In order to provide a proper mobile internet service, Mobile IP is necessary to support IP mobility. Service network should be a backbone network among mobile agents which support mobility, and MPLS(Multi-protocol Label Switching) of IETF(Internet Engineering Task Force) is being considered as a backbone network because of its speed, scalability and the excellent service capability. MPLS, however, doesn't provide a way to support the mobility of the nodes. In this paper, we present an efficient IMT-2000 network architecture using MPLS to handle Mobile IP. The proposed architecture combines the MPLS label distribution and Mobile IP registration. It doesn't use the layer 3 encapsulation, instead it uses layer 2 for tunneling the data, reduces the size of the header, and it can tunnel the data without delay, which is needed to look up the mobility binding list, as a result.

• Journal of KIISE:Information Networking
• /
• v.35 no.2
• /
• pp.120-129
• /
• 2008

The purpose of sensor network is gathering the information from sensor nodes. If there are selfish node that deliberately avoid packet forwarding to save their own energy, the sensor network has trouble to collect information smoothly. To solve this problem we suggest a mechanism which uses credit payment schema according to the amount of forwarding packets. Sensor nodes use credits to send their own message and they forward packets of other sensor nodes to get credits. To offer authenticity we combined the roles of sink node and server, also we used piggybacking not to send additional report message. The packet trace route is almost fixed because sensor node doesn't have mobility. In this case, it happens that some sensor nodes which don't receive forwarding packets therefore they can't get credit. So, we suggested the way to give more credits to these sensor nodes. Finally, we simulated the suggested mechanism to evaluate performance with ns2(network simulator). As a result, packet transmission rate was kept on a high rate and the number of arrival packets to sink node was increased. Also, we could verify that more sensor nodes live longer due to deceasing the energy consumption of sensor nodes.

• Journal of KIISE:Information Networking
• /
• v.35 no.1
• /
• pp.34-45
• /
• 2008

In dynamic wireless sensor networks where sources and sinks are moving or are created/died, control overheads for route establishment are increased and thus become one of the major factors for energy consumption. This study introduces prefetching and pruning for Directed Diffusion to remove redundant control messages. Prefetching collects path information for each event with "AnyEvent" in advance and gives quick responses without further flooding of requests. Pruning accumulates history information from previous requests and replies, and then stops forwarding a request towards where the event does not exist. Simulation results with ns show that it is possible to build implicit and soft infrastructures within a Directed Diffusion system through these active collection and passive accumulation and they improve energy consumption more as control overhead goes higher.

• Journal of Advanced Navigation Technology
• /
• v.20 no.6
• /
• pp.528-538
• /
• 2016

In this paper, an extend kalman filter based relative navigation algorithm is proposed for Link-K based relative navigation. Link-K is a tactical data link system for joint operation capability upgrade of ROK forces. Link-K is inter-operable with Link-16 and transmit and received information of operations and target. In Link-K communication channel, PPLI message including transmitter position and TOA measurement can be used for relative navigation. Therefore Link-K based relative navigation system can be operated. In this paper, software based simulations were carried out for operational feasibility test and performance verification as error factors of proposed Link-K based relative navigation system.

• Journal of KIISE:Information Networking
• /
• v.32 no.5
• /
• pp.551-560
• /
• 2005

To reduce the amount of the signaling messages occurred in movement, HMIPv6 has been introduced as the hierarchical mobility management architecture tor MIPv6 by regarding the locality of movements. When approaching the visited link, the authentication procedure should be done successfully prior to any motility support message exchanges. The AAA(Authentication, Authorization and Account) authentication service is applied gradually to the wireless LAN and Cellular networks. However, It may bring about the service latency for the sessions of requiring the real-time processing due to not providing the optimized signaling in local and frequent movements. In this paper, we propose the authentication architecture with 'delegation' scheme to reduce the amount of signaling message and latency to resume for local movements by integrating it with HMIPv6 architecture. We provide the integrated authentication model and analyze the performance and effectivity of our proposal and finally offer the analysis materials comparing to the exiting authentication scheme. It cuts down the cost to $33.6\%$ at average measurement.

• Journal of KIISE:Information Networking
• /
• v.29 no.5
• /
• pp.482-494
• /
• 2002

In E-mail based accounting system, the remitter does not have need to find collector's account number. To transfer money to a collector's account, what remitter need is just a collector's E-mail address. But the current E-mail based accounting systems are built on SSL technology. Basically SSL provides some security services - confidentiality, user authentication and data integrity, but does not provide non-repudiation. So, in the current E-mail based accounting system, it is possible to deny transaction. And there is no receipt of transaction. In this paper, we design and implementation of a S/MIME applied Secure Payment Mechanism. In our system, every account information - account number, receiver name, amount of money, etc. - is included in a 'check' message. And this message is protected under the Secure Web-mail using S/MIME. In a view point of the convenience, users using our system do not have need to find collector's account number. And in a view point of the security, our system provides confidentiality, user authentication, data integrity and non-repudiation. Moreover our system provides a receipt.

• Journal of KIISE:Computer Systems and Theory
• /
• v.27 no.3
• /
• pp.277-286
• /
• 2000

Switch-based network is suitable for the environment of demanding high performance network. Traditional shared-medium Local Area Networks(LANs) do not provide sufficient throughput and latency. Specially, communication performance is more important with multimedia application. In these environments, switch-based network results in high performance. A kind of switch-based network provides higher bandwidth and low latency. Thus high-speed switch is essential to build switch-based LANs. An effective switch design is the most important factor of the switch-based network performance, and is required for the multicast message processing. In the previous cut-through switching technique, switch element reconfiguration has the capability of multicasting and deadlock-free. However, it has problems of low throughput as well as large scale of switch. Therfore, effective multicating can be implemented by using divided hardware unicast and multicast. The objective of this thesis is to suggest switch configuration with these features.

• The Journal of the Korea Contents Association
• /
• v.17 no.1
• /
• pp.662-672
• /
• 2017

Recently, with the development of mobile devices and near field communication, mobile P2P networks have been actively studied to improve the limits of the existing centralized processing system. A peer has limited components such as batteries, memory and storage spaces in mobile P2P networks. The trust of a peer should be discriminated in order to share reliable contents in mobile P2P networks. In this paper, we propose a trust discrimination scheme considering limited resources in mobile P2P environments. The proposed scheme discriminates the trust of a peer by direct rating values using the rating information of the peer and indirect rating values by the other peers. The recent update time is included in the rating information. The proposed scheme reduces the redundant rating information by comparing the recent update times of the rating information. It is shown through performance evaluation that the proposed scheme reduces the number of messages and improves the accuracy of trust over the existing scheme.

• Journal of Korea Multimedia Society
• /
• v.3 no.5
• /
• pp.516-525
• /
• 2000

A lot of efforts have been made to develop a new technology for efficient distance education based on a powerful Internet service like World Wide Web. By developed distance education systems, we can study something we want at anytime and anywhere. However in spite of the excellent achievements we have made, something insufficient still is remained. Distance education methods only depending on static homepages or voices and simple drawings may be insufficient to support as much effects as in real class. So it is necessary to develop a new method for teaching students more feasibly and efficiently In this paper, we try to design and implement a lecture authoring system that offers effective distance education with voices, animations, camera images, drawings and etc.. We can expect the designed system can give more efficient education effects like a face-to-face lecture in real class. The enclosed function of intense compression enables to transmit the lectures more speedily. Besides it has caption processing function to serve additional informations to students with caption texts, messages and hyperlinks.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.2
• /
• pp.217-221
• /
• 2010

As the appearances of various new mobile devices and the explosive growth of mobile device users, many researches related to mobile P2P systems have been proceeded actively. In this paper, we propose a new search algorithm for the double-layered super peer system in the mobile environment. For the proposed search algorithm, we divide the entire experiment region into a grid of cells, each of which has the same size. The grid is configured properly by considering the communication range of a mobile device and the number of peers in the system. The proposed search algorithm is a partial flooding search method based on the directions of cells involved with the search. It reduces successfully the network traffic, but shows a low search hit ratio. To enhance the search hit ratio, we introduce a bridge-peer table for a super peer and utilize an n-way search. The experimental results show that the proposed algorithm made an average of 20~30% reduction in the number of message packets over the double-layered system. The success ratio was also improved about 2~5% over the double-layered system.