• Journal of Information Processing Systems
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• v.6 no.2
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• pp.147-162
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• 2010

In this paper, we present a fine-grained localization algorithm for wireless sensor networks using a mobile beacon node. The algorithm is based on distance measurement using RSSI. The beacon node is equipped with a GPS sender and RF (radio frequency) transmitter. Each stationary sensor node is equipped with a RF. The beacon node periodically broadcasts its location information, and stationary sensor nodes perceive their positions as beacon points. A sensor node's location is computed by measuring the distance to the beacon point using RSSI. Our proposed localization scheme is evaluated using OPNET 8.1 and compared with Ssu's and Yu's localization schemes. The results show that our localization scheme outperforms the other two schemes in terms of energy efficiency (overhead) and accuracy.

• International journal of advanced smart convergence
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• v.6 no.3
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• pp.9-16
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• 2017

In this paper, we propose a new routing protocol for wireless sensor networks. This protocol improves energy consumption of ML-LEACH by reducing the transmission distance of member node via Relay Node. Since clusters of each Layer in ML-LEACH are randomly formed, the distance, between member node and cluster head may be longer than specific distance, distance threshold value. To improve this, we propose the new routing protocol using 2-Hop transmission via Relay Node depending on the transmission distance of the member node.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3007-3019
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• 1993

For the same configuration, the stiffness of 6-node two dimensional isoparametric is stiffer than that of 8-node two dimensional isoparametric element. This phenomenon may be called 'Relative Stiffness Stiffening Phenomenon.' In this paper, the relative stiffness stiffening phenomenon was studied, and could be corrected by modifying the position of Gauss integral points used in the numerical integration of the stiffness matrix. For the same deformation (bending) energy of 6-node and 8-node two dimensional isoparametric elements, Gauss integral points of 6-node element have to move closer, in comparison with those of 8-node element, in the case of numerical integration along the thickness direction.

• ETRI Journal
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• v.42 no.3
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• pp.341-350
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• 2020

In a wireless sensor network (WSN), the data transmission technique based on the cooperative multiple-input multiple-output (CMIMO) scheme reduces the energy consumption of sensor nodes quite effectively by utilizing the space-time block coding scheme. However, in networks with high node density, the scheme is ineffective due to the high degree of correlated data. Therefore, to enhance the energy efficiency in high node density WSNs, we implemented the distributed source coding (DSC) with the virtual multiple-input multiple-output (MIMO) data transmission technique in the WSNs. The DSC-MIMO first compresses redundant source data using the DSC and then sends it to a virtual MIMO link. The results reveal that, in the DSC-MIMO scheme, energy consumption is lower than that in the CMIMO technique; it is also lower in the DSC single-input single-output (SISO) scheme, compared to that in the SISO technique at various code rates, compression rates, and training overhead factors. The results also indicate that the energy consumption per bit is directly proportional to the velocity and training overhead factor in all the energy saving schemes.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.766-769
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• 2005

In a ubiquitous environment made up of multiple sensors, most sensors participate in communications with limited battery, and the sensor node isn't able to participate in communications when all the battery is used up. When an existing authentication method is used for the sensor node which has to participate in a long term communication with limited battery, it creates a problem by making the length of network maintenance or sensor node's operation time relatively shorte. Therefore, a network structure where RM (Register Manager) node and AM (Authentication Manager) node are imported to solve the energy consumption problem during a communication process is presented in this thesis. This offers a low power protocol based on safety through a mutual authentication during communications. Through registration and authentication manager nodes, each sensor nodes are ensured of safety and the algorithm of key's generation, encryption/descramble and authentication is processed with faster operation speed. So the amount of electricity used up during the communications between sensor nodes has been evaluated. In case of the amount of electrical usage, an average of $34.783\%$ for the same subnet and 36.855 for communications with two different subnets, are reduced. The proposed method is a protocol which maintains the limited battery for a long time to increase the effectiveness of energy usage in sensor nodes and can also increase the participation rate of communication by sensor nodes.

• Journal of KIISE
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• v.44 no.9
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• pp.966-975
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• 2017

In Internet of Things (IoT), the aim of the nodes (called 'Things') is to exchange information with each other, whereby they gather and share information with each other through self decision-making. Therefore, we cannot apply existing aggregation algorithms of Wireless sensor networks that aim to transmit information to only a sink node or a central server, directly to the IoT environment. In addition, since existing algorithms aggregate information from all sensor nodes, problems can arise including an increasing number of transmissions and increasing transmission delay and energy consumption. In this paper, we propose the clustering and property based data exchange method for energy efficient information sharing. First, the proposed method assigns the properties of each node, including the sensing data and unique resource. The property determines whether the node can respond to the query requested from the other node. Second, a cluster network is constructed considering the location and energy consumption. Finally, the nodes communicate with each other efficiently using the properties. For the performance evaluation, TOSSIM was used to measure the network lifetime and average energy consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.763-770
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• 2014

In traditional routing protocols including LEACH for wireless sensor networks, nodes suffer from unbalanced energy consumption because the nodes require large transmission energy as the distance to the sink node increase. Multi-hop based routing protocols have been studied to address this problem. In existing protocols, each cluster head usually chooses the closest head as a relay node. We propose LEACH-CHT, in which cluster heads choose the path with least energy consumption to send data to the sink node. In our research, each hop, a cluster head selects the least cost path to the sink node. This method solves the looping problem efficiently as well as make it possible that a cluster head excludes other cluster heads placed farther than its location from the path, without additional energy consumption. By balancing the energy consumption among the nodes, our proposed scheme outperforms existing multi-hop schemes by up to 36% in terms of average network lifetime.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.5
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• pp.354-365
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• 2015

This work presents an Internet of Things (IoT) system for home energy management based on a custom-designed Impulse Radio Ultra-Wideband (IR-UWB) transceiver that targets a generic and multi-standard control system. This control system enables the interoperability of heterogeneous devices: it integrates various sensor nodes based on ZigBee, EnOcean and UWB in the same middleware by utilizing an ad-hoc layer as an interface between the hardware and software. The paper presents as a first the design of the IR-UWB transceiver for a portable sensor node integrated with the middleware layer, and also describes the receiver connected to the control system. The custom-designed low-power transmitter on the sensor node is fabricated with 130 nm CMOS technology. It generates a signal with a 1.1 ns pulse width while consuming $39{\mu}W$ at 1 Mbps. The UWB sensor node with a temperature measurement capability consumes 5.31 mW, which is lower than the power level of state-of-the-art solutions for smart-home applications. The UWB hardware and software layers necessary to interface with the control system are verified in over-the-air measurements in an actual office environment. With the implementation of the presented sensor node and its integration in the energy management system, we demonstrate achievement of the broad flexibility demanded for IoT.

• Journal of Plant Biotechnology
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• v.34 no.2
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• pp.161-166
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• 2007

In vitro shoot regeneration and multiple shoot induction has been obtained from the stolen node explants in Eremochloa ophiuroides (Munro) Hack. The highest number of shoots ($10.66{\pm}0.21$) was observed from initial explants after one month culture duration on Murashige and Skoog (MS) medium containing 6-benzyladenine (BA: 0.5 mg/l). First generation shoot was excised and sub-cultured on the same fresh media for further multiplication of shoots. An enhanced number of second round shoots ($15.33{\pm}0.21$) was obtained compared to the initial culture media containing BA (0.5 mg/l). The number of shoots/stolon node was higher among all the concentrations of BA than kinetin (KN). In vitro regenerated shoots were successfully rooted in the phytohormone free MS medium. Plantlets generated with roots were transferred to pots containing compound mixture of soil and kept in green house conditions. Acclimatized plants showed 100% survival rate with normal morphology in green house conditions. The present study demonstrates the effect of explant and different plant growth regulators towards in vitro response in E. ophiuroides. Moreover, the study reveals the effect of cytokinin on induction of shoot number per stolen node explant in E. ophiuroides.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3B
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• pp.149-157
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• 2012

In WSN environment, the sensor nodes collect sensed data, and transmit data to the BS. BS is difficult to trust the data from unauthenticated nodes. Therefore, many papers have been proposed about the node authentication and the safety of data. In the AM-E paper, data is delivered after node authentication. In this time, the sensor nodes are directly communicated to BS the AREQ/AREP message for authentication. Therefore, the sensor nodes consume more energy for authentication. Also, noes communicate directly with the BS for authentication will have problem due to the limited energy of nodes. In this paper, the same security with AM-E is supported, Furthermore, to minimize the energy consumption, IDE based hierarchical node authentication protocol is proposed. Compared with AM-E, the number of alive nodes is increased about 39%. Thus, the entire network life time is extended and energy efficiency is improved.