• The Journal of Korean Institute of Communications and Information Sciences
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• 제28권7A호
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• pp.451-466
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• 2003

Untethered nodes in mobile ad-hoc networks strongly depend on the efficient use of their batteries. In this paper, we propose a new metric, the drain rate, to forecast the lifetime of nodes according to current traffic conditions. This metric is combined with the value of the remaining battery capacity to determine which nodes can be part of an active route. We describe new route selection mechanisms for MANET routing protocols, which we call the Minimum Drain Rate (MDR) and the Conditional Minimum Drain Rate (CMDR). MDR extends nodal battery life and the duration of paths, while CMDR also minimizes the total transmission power consumed per packet. Using the ns-2 simulator and the dynamic source routing (DSR) protocol, we compare MDR and CMDR against prior proposals for power-aware routing and show that using the drain rate for power-aware route selection offers superior performance results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• 제41권8호
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• pp.27-33
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• 2004

A new multicast scheme for mobile nodes is proposed to support real-time communication in a more efficient way. In the proposed multicast scheme, the Xcast (a very flexible data plane mechanism) is integrated with the SIP (a very flexible control plane protocol) to support multicast for mobile nodes. The simulation results verify that the proposed scheme reduces unnecessary network traffic and achieves low latency of packets in the network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권9호
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• pp.2173-2193
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• 2013

In order to reduce the distribution cost of sensor nodes, a mobile sensor deployment has been proposed. The mobile sensor deployment can be solved by finding the optimal layout and planning the movement of sensor nodes with minimum energy consumption. However, previous studies have not sufficiently addressed these issues with an efficient way. Therefore, we propose a new deployment approach satisfying these features, namely a tree-based approach. In the tree-based approach, we propose three matching schemes. These matching schemes match each sensor node to a vertex in a rake tree, which can be trivially transformed to the target layout. In our experiments, the tree-based approach successfully deploys the sensor nodes in the optimal layout and consumes less energy than previous works.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제18권5호
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• pp.1-9
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• 2017

Recently, the active research into wireless sensor networks has led to the development of sensor nodes with improved performance, including their mobility and location awareness. One of the most important goals of such sensor networks is to transmit the data generated by mobile sensors nodes. Since these sensor nodes move in the mobile wireless sensor networks (MWSNs), the energy consumption required for them to transmit the sensed data to the fixed sink is increased. In order to solve this problem, the use of mobile sinks to collect the data while moving inside the network is studied herein. The important issues are the mobility and energy consumption in MWSNs. Because of the sensor nodes' limited energy, their energy consumption for data transmission affects the lifetime of the network. In this paper, a mobile-sink based energy-efficient clustering scheme is proposed for use in mobile wireless sensor networks (MECMs). The proposed scheme improves the energy efficiency when selecting a new cluster head according to the mobility of the mobile sensor nodes. In order to take into consideration the mobility problem, this method divides the entire network into several cluster groups based on mobile sinks, thereby decreasing the overall energy consumption. Through both analysis and simulation, it was shown that the proposed MECM is better than previous clustering methods in mobile sensor networks from the viewpoint of the network energy efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권3호
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• pp.872-885
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• 2015

The rapid increase of smart mobile devices and mobile applications has led to explosive growth of data traffic in cellular network. Offloading data traffic becomes one of the most urgent technical problems. Recent work has proposed to exploit opportunistic communications to offload cellular traffic for mobile data dissemination services, especially for accepting large delayed data. The basic idea is to deliver the data to only part of subscribers (called target-nodes) via the cellular network, and allow target-nodes to disseminate the data through opportunistic communications. Human mobility shows temporal and spatial characteristics and predictability, which can be used as effective guidance efficient opportunistic communication. Therefore, based on the regularity of human mobility we propose NodeRank algorithm which uses the encounter characteristics between nodes to choose target nodes. Different from the existing work which only using encounter frequency, NodeRank algorithm combined the contact time and inter-contact time meanwhile to ensure integrity and availability of message delivery. The simulation results based on real-world mobility traces show the performance advantages of NodeRank in offloading efficiency and network redundant copies.

• Proceedings of the KSRS Conference
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.678-682
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• 2005

IETF suggested AAA for safe and reliable user authentication on various network and protocol caused by development in internet and increase in users. Diameter standard authentication system does not provide mutual authentication and non-repudiation. AAA authentication system using public key was suggested to supplement such Diameter authentication but application in mobile service control nodes is difficult due to overhead of communication and arithmetic. ID based AAA authentication system was suggested to overcome such weak point but it still has the weak point against collusion attack or forgery attack. In this thesis, new ID based AAA authentication system is suggested which is safe against collusion attack and forgery attack and reduces arithmetic quantity of mobile nodes with insufficient arithmetic and power performance. In this thesis, cryptological safety and arithmetical efficiency is tested to test the suggested system through comparison and assessment of current systems. Suggested system uses two random numbers to provide stability at authentication of mobile nodes. Also, in terms of power, it provides the advantage of seamless service by reducing authentication executing time by the performance of server through improving efficiency with reduced arithmetic at nodes.

• ETRI Journal
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• 제44권3호
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• pp.389-399
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• 2022

Wireless sensor networks (WSNs) are one of the basic building blocks of Internet of Things (IoT) systems. However, the wireless sensing nodes in WSNs suffer from energy constraint issues because the replacement/recharging of the batteries of the nodes tends to be difficult. Furthermore, a number of realistic IoT scenarios, such as habitat and battlefield monitoring, contain mobile sensing elements, which makes the energy issues more critical. This research paper focuses on realistic WSN scenarios that involve mobile sensing elements with the aim of mitigating the attendant energy constraint issues using the concept of radio-frequency (RF) energy extraction. The proposed technique incorporates a cluster head election workflow for WSNs that includes mobile sensing elements capable of RF energy harvesting. The extensive simulation analysis demonstrated the higher efficacy of the proposed technique compared with the existing techniques in terms of residual energy, number of functional nodes, and network lifetime, with approximately 50% of the nodes found to be functional at the 4000th, 5000th, and 6000th rounds for the proposed technique with initial energies of 0.25, 0.5 and 1 J, respectively.

• Journal of the Korea Society of Computer and Information
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• 제22권9호
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• pp.33-40
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• 2017

In this paper, we propose a sink-location management and data-routing scheme to effectively support the mobile sink in solar-powered WSN. Battery-based wireless sensor networks (WSNs) have a limited lifetime due to their limited energy, but solar energy-based WSNs can be supplied with energy periodically and can operate forever. On the other hand, introduction of mobile sink in WSNs can solve some energy unbalance problem between sink-neighboring nodes and outer nodes which is one of the major challenges in WSNs. However, there is a problem that additional energy should be consumed to notify each sensor node of the location of the randomly moving mobile sink. In the proposed scheme, one of the nodes that harvests enough energy in each cluster are selected as the cluster head, and the location information of the mobile sink is shared only among the cluster heads, thereby reducing the location management overhead. In addition, the overhead for setting the routing path can be removed by transferring data in the opposite direction to the path where the sink-position information is transferred among the heads. Lastly, the access node is introduced to transmit data to the sink more reliably when the sink moves frequently.

• The KIPS Transactions:PartC
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• 제15C권1호
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• pp.51-60
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• 2008

Micro-mobility protocols have been developed to reduce the control message overhead due to movements of mobile nodes. With the spread of mobile devices, services using mobile nodes are increasing and multicast services are becoming more important in providing multimedia services. In this paper we propose a new multicast protocol suitable for micro-mobility environments. The proposed protocol is designed to maintain optimal multicast routing paths and continue to provide multicast services without disruption in spite of frequent handoffs due to movements of mobile nodes. We used simulation to evaluate the proposed protocol, compared its performance with existing multicast protocols for mobile environments including bi-directional tunneling, remote subscription, and MMA, and observed that the proposed protocol exhibited better performance in terms of transmission success ratio and overhead on the network.

• Convergence Security Journal
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• 제12권4호
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• pp.91-96
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• 2012

MANET is developed technique fairly among many field of wireless network. Nodes which consist of MANET transmit data using multi-hop wireless connection. Caching scheme is technique which can improve data access capacity and availability of nodes. Previous studies were achieved about dynamic routing protocol to improve multi-hop connection of moving nodes. But management and maintenance of effective cache information because of movement of nodes is not easy. In this study, we proposed cluster-based caching scheme to manage connection by decreasing overhead and moving of nodes as moving node discovers cache of wish information. And HLP was used to maintain effective cache table in each cluster head. Efficiency of proposed technique in this study was confirmed by experiment.