• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10B
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• pp.876-884
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• 2008

In this paper, we propose an asynchronous MAC protocol to minimize energy usage and to maximize data throughput for a wireless sensor network in multi channel environments. Our proposed SPMC-MAC (Slim Preamble Multi-Channel Media Access Control) adopts the preamble sliming mechanism proposed in [6] that takes advantage of the knowledge about the wakeup time of the receiver node. The preamble contains the receiver's ID and a randomly selected channel ID for data communication, and it is transmitted over a dedicated common channel. The power control has the benefit of keeping an appropriate number of nodes with the communication range, resulting in reduced collision and interference. We compare our SPMC-MAC and X-MAC extensively in terms of energy consumption and throughput using mathematical analysis and simulation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.155-161
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• 2015

Efficient energy consumption is a one of the key issues in wireless sensor networks. Clustering-based routing algorithms have been popular solutions for such an issue. Re-clustering is necessary for avoiding early energy drain of cluster head nodes in such routing strategies. The re-clustering process itself, however, is another source of energy consumption. It is suggested in this work to adaptively set the frequency of re-clustering by comparing the energy levels of cluster heads and a threshold value. The algorithm keeps the clusters if all the cluster heads' energy levels are greater than the threshold value. We confirm through simulations that the suggested algorithm shows better energy efficiency than the existing solutions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.580-581
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• 2018

In order to reduce end-to-end delay in EH-WSN (energy harvestin wireless sensor netowk), medium access control protocols using multi-hop routing technique have been studied. In a real environment, there are many situations where it is difficult to harvest enough energy than the energy consumed. Therefore, it is required to design a MAC protocol that allows nodes to reliably relay data without exhausting power in multi-hop transmission. In this paper, we propose a power-efficient MAC protocol that can select the relay node according to the residual power and the energy collection rate to increase network lifetime.

• The KIPS Transactions:PartC
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• v.13C no.3 s.106
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• pp.317-322
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• 2006

This paper presents an efficient user-cooperation protocol associated with cyclic coding for WSNs (Wireless Sensor Networks) using LEACH(Low-Energy Adaptive Clustering Hierarchy). Since the proposed user-cooperation requires no CSI(Channel State Information) at both transmitter and receiver, and encoding and decoding of cyclic codes are simple, the processing complexity of sensor nodes is significantly reduced. Simulation results reveal such a combination can save the network energy up to 10dB over single-hop transmission at BER of $10^{-4}$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.721-727
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• 2009

Wireless Sensor Networks(WSN) make use of low cost and energy constrained sensor nodes. Thus, reaching the successful execution of its tasks with low energy consumption is one of the most important issues. The limitation of existing hierarchical algorithms is that many times the data are transmitted to the opposite direction to the sink. In this paper, DDACM (Data Direction Aware Clustering Method) is proposed. In this method, the nearest node to the sink is elected as cluster head, and when its energy level reaches a threshold value, the cluster head is reelected. We also make a comparison with LEACH showing how this method can reduce the energy consumption minimizing the reverse direction data transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.125-135
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• 2010

Recently, the problem of global warming has issued seriously, so Green IT(Information Technology) using RFID/USN is concerned in order to solve environmental problems. In this paper, we implemented that public area like an underground parking lot could reduce unnecessary energy consumption used by lighting control system based on Ubiquitous Sensor Networks. The lighting control system for underground parking lot is comprised of intersection nodes for watching cars enter and leave, and light node for controlling light. It applies the routing protocol based on hierarchical cluster, hierarchical addressing method, and probability filtering method for the specific place like an underground parking lot. The result after experiments shows that the lighting control system could decrease electrical energy consumption to around 61.7%.

• Journal of Communications and Networks
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• v.16 no.4
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• pp.371-377
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• 2014

Localized topology control is attractive for obtaining reduced network graphs with desirable features such as sparser connectivity and reduced transmit powers. In this paper, we focus on studying how to prolong network lifetime in the context of localized topology control for wireless multi-hop networks. For this purpose, we propose an energy efficient localized topology control algorithm. In our algorithm, each node is required to maintain its one-hop neighborhood topology. In order to achieve long network lifetime, we introduce a new metric for characterizing the energy criticality status of each link in the network. Each node independently builds a local energy-efficient spanning tree for finding a reduced neighbor set while maximally avoiding using energy-critical links in its neighborhood for the local spanning tree construction. We present the detailed design description of our algorithm. The computational complexity of the proposed algorithm is deduced to be O(mlog n), where m and n represent the number of links and nodes in a node's one-hop neighborhood, respectively. Simulation results show that our algorithm significantly outperforms existing work in terms of network lifetime.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1133-1145
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• 1996

A method is proposed to predict the deformed shape of the structure subjected to the unknown external loads using the signal from the piezoceramic sensors. Such a shape estimation is based on the linear relationship between the deformation of structure and the signal from sensor, which is calculated using finite element method. The deformed shape is, then calculated using the linear matrix and the signals from the piezoceramic sensors attached to the structures. For the purpose, a structural analysis program is developed using a multi-layerd finite element of 8 nodes with 3 displacement and one voltage degrees of freedom at each node. The multiple layers with the different material properties can be layered within the element. The incompatible mode with the element is found to be crucial to catch the bending behavior accurately. The accuracy of the program is, then, verified by being compared with the experimental results performed by Crawley. The proposed shape estimation method is also verified for the different loads and sensor size. It is shown that the results of shape estimation method using the linear matrix well predicts the deflections compared with those of finite element method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.17-22
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• 2011

The underwater environments are quite different from the terrestrial ones in terms of the communication channel and constrains. In underwater wireless sensor network, the probability of node failure is high because sensor nodes are deployed in more harsh environments than the ground based networks and moved by waves and currents. There are researches considering the communication environments of underwater to improve the data transmission throughput. In this paper, we present a checkpointing scheme of the cluster heads that recoveries from a cluster head failure quickly. Experimental results show that the proposed scheme enhances the reliability of the networks and more efficient in terms of the energy consumption and the recovery latency than without checkpointing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2B
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• pp.107-116
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• 2006

In this paper, we propose a Sensing Resolution-based Grouping(SRG) protocol for wireless sensor networks. SRG is intended for meeting the application's sensing objectives, where sensor nodes are densely deployed and have the determinate accuracy requirement. The primary contribution of this paper is active group header node selection and round-robin procedure, which increase the sensing accuracy and evenly distribute the node energy consumption. The second contribution is use of energy efficient intermediate node selection by considering group size and energy consumption. We present the design principle of SRG and provide simulation results.