• Journal of Communications and Networks
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• v.18 no.5
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• pp.857-869
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• 2016

This paper proposes an X-MAC/BEB protocol that runs a binary exponential backoff (BEB) algorithm on top of an X-MAC protocol to save more energy by reducing collision, especially in densely populated wireless sensor networks (WSNs). X-MAC, a lightweight asynchronous duty cycle medium access control (MAC) protocol, was introduced for spending less energy than its predecessor, B-MAC. One of X-MAC 's conspicuous technique is a mechanism to allow senders to promptly send their data when their receivers wake up. X-MAC, however, has no mechanism to deal with sudden traffic fluctuations that often occur whenever closely located nodes simultaneously diffuse their sense data. To precisely evaluate the impact of the BEB algorithm on X-MAC, this paper builds an analytical model of X-MAC/BEB that integrates the BEB model with the X-MAC model. The analytical and simulation results confirmed that X-MAC/BEB outperformed X-MAC in terms of throughput, delay, and energy consumption, especially in congested WSNs.

• Journal of information and communication convergence engineering
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• v.10 no.4
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• pp.343-348
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• 2012

ZigBee Network is enabling technology for home automation, surveillance and monitoring system. For better secure network environment, secure and robust security model is important. The paper proposes an application, attribute-based proxy re-encryption on ZigBee networks. The method can distribute the authority to designated sensor nodes to decrypt re-encrypted ciphertext with associated attributes. However, a previous method is required to compute complex pairing operations. The high complexity is not suited to low resource device sensor networks, and it does not provide routing security either. To resolve these problems, we present a novel mechanism. The method can reduce overhead by imposing overhead to full function devices and ensure routing paths as well.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.707-710
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• 2007

The sensor network by using Utrasonic transceiver is concerned about the dampness of the signals caused by distance among the nodes, the distortion for speed of data trasmission and the transport protocol. The motes are sized $50mm\times60mm$, the ultrasonic analog part sized $30mm\times40mm$ and record 2% error rate for data transport.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.4
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• pp.187-191
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• 2012

In these days, there are huge increases of concerning underwater acoustic sensor networks (UWASNs) to explore marine resources and to monitor climate change. To collect information from sensor nodes which are randomly deployed in underwater, Multi-Dimensional Scaling (MDS) based locating methods have been recently introduced, which consider sound speed to be constant in underwater. However, underwater sound speed tends to vary depending on underwater environment factors, such as depth, temperature, and salinity. In this paper, we propose a method considering environment factors, can influence upon sound speed in underwater, and introduce experimental setup which can follow up environmental factors.

• Journal of information and communication convergence engineering
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• v.7 no.4
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• pp.521-524
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• 2009

Park proposed a forward & backward Secure key management scheme in wireless sensor networks for Process Control Systems (PCSs) or Supervisory Control and Data Acquisition (SCADA) systems [7]. The scheme, however, is still vulnerable to an attack called "sandwich attack": two nodes captured at times $t_1$ and $t_2$, respectively, surrenders all the group keys used between times $t_1$ and $t_2$. In this paper, we propose a fix to the scheme, which can limit the vulnerable time duration to an arbitrarily chosen time span while keeping the forward and backward secrecy of the scheme untouched.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.593-594
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• 2015

In wireless sensor networks (WSNs), due to the very low data rate, the sleeping schedule is usually used to save consumed energy and prolong the lifetime of nodes. However, duty-cycled approach can cause a high end-to-end (E2E) delay. In this paper, we study a node scheduling algorithm in WSNs such that E2E delay meets bounded delay with a given probability. We have applied the probability theory to spot the relationship between E2E delay and node interval. Simulation result illustrates that we can create the network to achieve given delay with prior probability and high energy use efficient as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.598-603
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• 2007

In this paper we propose a QMAC to support QoS(Quality of Service) and to enhance the transmission throughput in Wireless Sensor Networks(WSNs). In the proposed QMAC, sender nodes send transmission request packets with QoS requirements to the receivers node using CSMA/CA MAC protocol. And the receiver node assigns slots according to the packet priority, network topology, and the amount of traffics using TDMA. Using QMAC we get the enhanced throughput and QoS support by lowering the duplicated slot assignment.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.2
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• pp.85-93
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• 2016

The existence of correlation characteristics brings significant potential advantages to the development of efficient routing protocols in wireless sensor networks. This research proposes a new simple method of clustering sensor nodes into correlation groups in multiple-correlation areas. At first, the evaluation of joint entropy for multiple-sensed data is considered. Based on the evaluation, the definition of correlation region, based on entropy theory, is proposed. Following that, a correlation clustering scheme with less computation is developed. The results are validated with a real data set.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1189-1190
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• 2008

Wireless sensor networks (WSN) have attracted much attention in recent years due to their potential use in many applications such as border protection and combat field surveillance. Given the criticality of such applications, maintaining a dependable operation of the network is a fundamental objective. However, the resource constrained nature of sensor nodes and the ad-hoc formation of the network, often coupled with an unattended deployment, pose non-conventional challenges and motivate the need for special techniques for dependable design and management of WSN. In this article, we highlight the potential of careful positioning of the base station (BS), which acts as a sink resources.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.615-616
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• 2008

Generally, distance between sensor nodes is measured using received signal strength indicator (RSSI) in wireless sensor network (WSN). Since RSSI is not absolutely accurate and stable in indoor environment, the performance of position estimation largely depends on estimation methods. In this paper, performance evaluation is presented to compare trilateration based positioning technique and collaborative ranging (CR) technique. From evaluation results, CR method is shown to be better than trilateration based method in terms of accuracy and precision.