• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.225-234
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• 2012

In Wireless Sensor Networks (WSNs) where deployed sensors are not stationary, the most important demand of is to design a cost effective and reliable network. This paper proposes an energy aware network construction and routing scheme, which is based on the hierarchical approach to distribute the task in some sensors in order to prolong the network lifetime. It aims to make even the energy consumption on constitute nodes. With the node hierarchy, the sink initiates the construction by electing gateway nodes in the network and the elected gateway nodes participate to form logical clusters by electing a cluster head in each cluster. Then, the cluster heads aggregate data from the sensing sensors and transmit the data to the sink through the gateway. Our simulation result illustrates that the proposed scheme provides a basement to reduce the source of energy dissipation in network construction, and as well as in data routing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.437-442
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• 2011

As an Internet Engineering Task Force (IETF) Working Group, 6LoWPAN is standardizing the IPv6 packet transfer technology in accordance with IEEE 802.15.4. It has completed two Request for Comments (RFC) documents, one of which, RFC 4944, addresses fragmentation, reassembly, and header compression technologies. In this paper, a communication mechanism is proposed to provide efficient communication between 6LoWPAN and external nodes. In this mechanism, the gateway between 6LoWPAN and external networks serves as the proxy gateway between nodes. The simulation was conducted using QualNet to compare the performance of the proposed mechanism and the existing RFC 4944 method. The comparative analysis of the proposed mechanism and the existing method showed that the proposed method performed better.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.6
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• pp.139-150
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• 2019

IoT(Internet of Things) security is becoming increasingly important because IoT potentially has a variety of security threats, including limited hardware specifications and physical attacks. This paper is a study on the certification technology suitable for the lightened IoT environment, and we propose a system in which many gateways share authentication information and issue authentication tokens for mutual authentication using blockchain. The IoT node can be issued an authentication token from one gateway to continuously perform authentication with a gateway in the block-chain network using an existing issued token without performing re-authentication from another gateway participating in the block-chain network. Since we do not perform re-authentication for other devices in a blockchain network with only one authentication, we proposed multi phase authentication consisting of device authentication and message authentication in order to enhance the authentication function. By sharing the authentication information on the blockchain network, it is possible to guarantee the integrity and reliability of the authentication token.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.613-619
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• 2020

Hybrid media access control (MAC) is used in internet of things (IoT) network, because of communication feature concern with data capacity and communication interval between gateway and sensor nodes and the cost efficiency. Hybrid MAC consists of TDMA and CSMA generally. The distance between gateway and sensor node is openly changed in marine IoT network. Therefore, it is needed to control the period of timeslot of hybrid MAC used in marine IoT network. In this paper, the design rule of TDMA timeslot with the variable period depending on communication distance was proposed. It was confirmed from the analysis that 72 times communication between gateway and sensor nodes is possible in LoRa network by using the proposed TDMA variable timeslot scheme.

• Journal of Internet Computing and Services
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• v.5 no.3
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• pp.25-33
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• 2004

Mobile IP Low Latency Handoffs(l) allow greater support for real-time services on a Mobile IP network by minimizing the period of time when a mobile node is unable to send or receive IP packets due to the delay in the Mobile IP Registration process. However, on Mobile IP network with AAA servers that are capable of performing Authentication, Authorization, and Accounting(AAA) services, every Registration has to be traversed to the home network to achieve new session keys, that are distributed by home AAA server, for a new Mobile IP session. This communication delay is the time taken to re-authentication the mobile node and to traverse between foreign and home network even if the mobile node has been previously authorized to old foreign agent. In order to reduce these extra time overheads, we present a method that performs Low Latency Handoffs without requiring further involvement by home AAA server. The method re-uses the previously assigned session keys. To provide confidentiality and integrity of session keys in the phase of key exchange between agents, it uses a key sharing method by gateway foreign agent that performs a trusted thirty party. The proposed method allows the mobile node to perform Low Latency Handoffs with fast as well as secure operation.

• Journal of KIISE:Information Networking
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• v.36 no.5
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• pp.405-412
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• 2009

Mobile ad hoc networks (MANETs) allow mobile nodes to communicate among themselves via wireless multiple hops without the help of the wired infrastructure. In the MANET, it is required not only a route setup mechanism that makes nodes not within each other's transmission range communicate but also mechanism in order for a node to auto-configure a unique address. In this paper, we propose an address auto-configuration mechanism when MANET is connected to the Internet via several Internet Gateways and all gateways advertise the same network prefix. By using the proposed mechanism, once a node configures an Internet topologically correct and globally unique IP address, then the node can utilize the configured address even though the node moves within the MANET. Through the simulations, we analyze the performance of our proposed mechanism and, from the simulation results, we show that out proposed mechanism outperforms the existing mechanism.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.1
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• pp.79-89
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• 2004

Mobile IP Low Latency Handoffs allow greater support for real-time services on a Mobile W network by minimizing the period of time when a mobile node is unable to send or receive IP packets due to the delay in the Mobile IP Registration process. However, on Mobile IP network with AAA servers that are capable of performing Authentication, Authorization, and Accounting(AAA) services, every Registration has to be traversed to the home network to achieve new session keys, that are distributed by home AAA server, for a new Mobile IP session. This communication delay is the time taken to re-authenticate the mobile node and to traverse between foreign and home network even if the mobile node has been previously authorized to old foreign agent. In order to reduce these extra time overheads, we present a method that performs Low Latency Handoffs without requiring funker involvement by home AAA server. The method re-uses the previously assigned session keys. To provide confidentiality and integrity of session keys in the phase of key exchange between agents, it uses a key sharing method by gateway foreign agent that Performs a ousted thirty party. The Proposed method allows the mobile node to perform Low Latency Handoffs with fast as well as secure operation

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1589-1597
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• 2016

In this paper, we propose a system in a large-scale environment, such as desert and ocean, that can reduce the overall transmission power consumption in mobile sensor network. It is known that the transmission power consumption in wireless sensor network is proportional to the square of transmission distance. Therefore, if the locations of mobile sensors are far from the sink node, the power consumption required for data transmission increases, leading to shortened operating time of the sensors. Hence, in this paper, we propose a system that can reduce the power consumption by allowing to transmit data only if the transmission range of the sensors is within a predetermined distance. Moreover, the energy efficiency of the overall sensor network can even be improved by reducing the number of data transmissions at the sink node to gateway based on compressed sensing. The proposed system is actually implemented using Arduino and Raspberry Pi and it is confirmed that source data can be approximately decoded even when the gateway received encoded data fewer than the required number of data from the sink node. The performance of the proposed system is analyzed in theory.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.12
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• pp.17-23
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• 2010

In the mobile cloud computing, the mobile node should request and receive the services while being connected. In PMIPv6, all packets sent by mobile nodes or correspondent nodes are transferred through the local mobility anchor. This unnecessary detour still results in high delivery latency and significant processing cost. Several PMIPv6 route optimization schemes have been proposed to solve this issue. However, they also suffer from the high signaling costs and handover latency when determining the optimized path. We propose the route optimization handover scheme which adopts the prediction algorithm in PFMIPv6. In the proposed scheme, the new mobile access gateway establishes the bi-directional tunnel with the correspondent node's MAG using the context message when the mobile node's handover is imminent. This tunnel may eliminate the need of separate route optimization procedure. Hence, the proposed scheme can reduce the signaling cost than other conventional schemes do. Analytical performance evaluation is preformed to show the effectiveness of the proposed scheme. The result shows that our scheme is more effective than other schemes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.445-450
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• 2011

In this paper, we describe the implementation of an wireless sensor network testbed. We developed a web-based sensor network gateway and enhanced the Surge program which is used for sending and routing of packets in the sensor field. The developed program can transmit the source data of sensor nodes to the sink node via multi-hop routing, and deliver user commands to actuate sensor related equipments. Moreover, in this testbed, the data transport path from a node to the sink can be monitored. Thus we can approximate the network topology and the relative positions of sensor nodes. We also describe an application of the testbed that is used for controlling a remote robot.