• Journal of Korea Society of Industrial Information Systems
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• v.17 no.1
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• pp.63-71
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• 2012

Most of sensor networks are difficult to be debugged, verified, and upgraded once they are deployed in the fields, for they are usually deployed in real world and large scale. Therefore, before deploying the sensor networks, we should test and verify them sufficiently in realistic testbeds. However, since we need to control physical environments which interact with sensor networks, it takes much of time and cost to test and verify sensor networks at the level of resource-constrained sensor nodes in such environments. This paper proposes an efficient software framework for evaluating and verifying sensor networks in the view points of network and application operations (i.e., accuracy of sensing algorithms). Applying the proposed software framework to the development of a simulator for a smart parking application based on wireless sensor network, this paper verifies the feasibility of the proposed framework.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.9
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• pp.626-633
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• 2006

The wireless sensor networks are sensing, computing and communication infrastructures that allow us to monitor, instrument, observe, and respond to phenomena in the harsh environment. Sensor operating systems that run on tiny sensor nodes are the key to the performance of the distributed computing environment for the wireless sensor networks. Therefore, sensor operating systems should be able to operate efficiently in terms of energy consumption and resource management. In this paper, we present an efficient memory allocation scheme to improve the time and space efficiency of memory management for the sensor operating systems. Our experimental results show that the proposed scheme performs efficiently in both time and space compared with existing memory allocation mechanisms.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1337-1342
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• 2012

In recent years, many researches in Home Networking are being progressed actively. Most of techniques for Home Networking are based on wired but the technique for wireless connection is also needed. This paper focuses on wireless connection in Home Networking. Of many of wireless technologies, such as Wireless LAN, Bluetooth, or HomeRF, we especially propose to apply the new technique called Wireless Sensor Network. We present hardware and protocol stack design consideration for wireless sensor node and wireless sensor network, and then we present how to apply wireless sensor network to Home Networking and how to constitute Wireless Home-Networking with a variety of sensor nodes. Finally, we introduce the wireless sensor node system designed by us and conclude this paper.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.6
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• pp.127-134
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• 2016

WBSN (Wireless Body Sensor Network), also called WBAN (Wireless Body Area Networks) generally, is a kind of WSN (Wireless Sensor Network) applications, which is composed of the various sensor nodes residing in human body embodied or in wearable way. The measured data at each sensor node in WBSN requires being synchronized at sink node for exact analysis for status of human body, which is like WSN. Although many time synchronization protocols for WSN has been already developed, they are not appropriate to WBSN. In this paper, a new time synchronization protocol for WBSN considering the characteristics of WBSN is proposed. The proposed scheme is not only simple, but also consumes less power, leading to increasing network life time. We will show that the proposed scheme is appropriate to WBSN by evaluating its performance by simulation.

• Journal of KIISE:Databases
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• v.36 no.4
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• pp.306-313
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• 2009

Top-k queries are issued to find out the highest (or lowest) readings in many sensor applications. Many top-k query processing algorithms are proposed to reduce energy consumption; FILA installs a filter at each sensor node and suppress unnecessary sensor updates; PRIM allots priorities to sensor nodes and collects the minimal number of sensor reading according to the priorities. However, if many sensor reading converge into the same range of sensor values, it leads to a problem that many false positives are occurred. In this paper, we propose a cluster-based approach to reduce them effectively. Our proposed algorithm operates in two phases: top-k query processing in the cluster level and top-k query processing in the tree level. False positives are effectively filtered out in each level. Performance evaluations show that our proposed algorithm reduces about 70% false positives and achieves about 105% better performance than the existing top-k algorithms in terms of the network lifetime.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.4
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• pp.158-168
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• 2009

As nation and society progresses, urban ground facilities and their management system get more complicated and the cost and effort to control the system efficiently grows exponentially. This study suggests to the deployment method of a sensor node by Wireless Sensor Network for controling the Urban Ground Facilities of National Facilities. First, we achieve the management facilities and method using the first analysis and then make the coverage of sensing and then set up the Sensor Node in Urban Ground Facilities. Second, we propose the solution way of repetition by the second analysis. And, we embody the GIS program by Digital Map and this method, we improve the reality by overlapping an aerial photo. Also we make an experience on the sensor node allocation using making program. we can remove the repetition sensor node about 50%, and we can confirm that the sensor nodes are evenly distributed on the road.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2329-2336
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• 2010

Hierarchical tree routing is a inefficient routing method of transmitting data in a wireless sensor network. Zigbee routing which is made to improve inefficiency of the hierarchical tree routing only fulfills the tree routing when a destination node don't exists in neighbor nodes of a router. We suggest a TFSR algorithm that is improved more than the zigbee routing. The TFSR algorithm generates a family set included a parent node and child nodes and over of a destination node, and uses this information. According to simulation results, the TFSR algorithm reduce routing costs over 30 percent in comparison with the hierarchical tree routing and the zigbee routing.

• Journal of information and communication convergence engineering
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• v.15 no.1
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• pp.7-13
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• 2017

We consider a distributed estimation where many nodes remotely placed at known locations collect the measurements of the parameter of interest, quantize these measurements, and transmit the quantized data to a fusion node; this fusion node performs the parameter estimation. Noting that quantizers at nodes should operate in a non-regular framework where multiple codewords or quantization partitions can be mapped from a single measurement to improve the system performance, we propose a low-weight estimation algorithm that finds the most feasible combination of codewords. This combination is found by computing the weighted sum of the possible combinations whose weights are obtained by counting their occurrence in a learning process. Otherwise, tremendous complexity will be inevitable due to multiple codewords or partitions interpreted from non-regular quantized data. We conduct extensive experiments to demonstrate that the proposed algorithm provides a statistically significant performance gain with low complexity as compared to typical estimation techniques.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.382-385
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• 2004

In this paper, a new clustering algorithm using the Guaranteed Distance is proposed. In the new algorithm, the appropriate distribution of clusterheads is accomplished by guarantee the stochastic average distance between clusterhead (CH)s. Using this algorithm, the communication cost from clusterheads to their member nodes and the load variance in each clusterheads are reduced. Therefore, the network lifetime can be extended and the fair energy consumption for all nodes can be achieved.

• Journal of information and communication convergence engineering
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• v.16 no.3
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• pp.142-147
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• 2018

We present a practical design algorithm for quantizers at nodes in distributed systems in which each local measurement is quantized without communication between nodes and transmitted to a fusion node that conducts estimation of the parameter of interest. The benefits of vector quantization (VQ) motivate us to incorporate the VQ strategy into our design and we propose a low-complexity design technique that seeks to assign vector codewords into sets such that each codeword in the sets should be closest to its associated local codeword. In doing so, we introduce new distance metrics to measure the distance between vector codewords and local ones and construct the sets of vector codewords at each node to minimize the average distance, resulting in an efficient and independent encoding of the vector codewords. Through extensive experiments, we show that the proposed algorithm can maintain comparable performance with a substantially reduced design complexity.