• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.1
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• pp.31-37
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• 2008

In this paper, we propose an entropy-based routing protocol to effectively support both stable route construction and route lifetime in Mobile Ad-hoc Wireless Sensor Networks (MAWSN). The basic idea and feature of the proposed routing protocol are as follows. First, we construct the stable routing routes based on entropy concept using mobility of mobile nodes. Second, we consider a realistic approach, in the points of view of the MAWSN, based on mobile sensor nodes as well as fixed sensor nodes in sensor fields while the conventional research for sensor networks focus on mainly fixed sensor nodes. The performance evaluation of the proposed routing protocol is performed via simulation using OPNET(Optimized Network Engineering Tool) and analysis. The results of the performance evaluation show that the proposed routing protocol can efficiently support both the construction of stable route and route lifetime in mobile ad-hoc wireless networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2B
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• pp.148-158
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• 2011

Stationary nodes and mobile nodes co-exist wireless sensor network(WSN) can provide variety of new services. The stationary sensor node acts not only the gathering the environmental sensing data but also a access point to bidirectional communication with numerous mobile sensor nodes(mobile node), and the mobile sensor nodes are installed inside mobile objects and identify the location in real-time and monitor the internal status of the object. However, only using the legacy WSN protocol, it is impossible to set up the stable network due to the several reasons caused by the free-mobility of the mobile nodes. In this paper, we suggest three methods to increase the hit-ratio of the asynchronous message delivery(AMD) among mobile nodes. We verified the performance of the suggested methods under the stationary-mobile co-existed WSN testbed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3357-3376
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• 2015

Wireless sensor network is an important research topic that has attracted a lot of attention in recent years. However, most of the interest has focused on wireless sensor network to gather scalar data such as temperature, humidity and vibration. Scalar data are insufficient for diverse applications such as video surveillance, target recognition and traffic monitoring. However, if we use camera sensors in wireless sensor network to collect video data which are vast in information, they can provide important visual information. Video sensor networks continue to gain interest due to their ability to collect video information for a wide range of applications in the past few years. However, how to efficiently store the massive data that reflect environmental state of different times in video sensor network and how to quickly search interested information from them are challenging issues in current research, especially when the sensor network environment is complicated. Therefore, in this paper, we propose a fast algorithm for extracting key frames from video and describe the design and implementation of key frame extraction and sharing in Android for wireless video sensor network.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.673-674
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• 2008

This paper presents a new navigation algorithm of an autonomous mobile robot with vision and IR sensors, Zigbee Sensor Network using fuzzy rules. We also show that the developed mobile robot with the proposed algorithm is navigating very well in complex unknown environments.

• Journal of information and communication convergence engineering
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• v.10 no.4
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• pp.365-371
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• 2012

In recent years, researchers have been attracted to clustering methods to improve communication and data transmission in a network. Compared with traditional wireless networks, wireless sensor networks are energy constrained and have lower data rates. The concept of implementing a clustering algorithm in an existing project on gateway relocation is being explored here. Low energy adaptive clustering hierarchy (LEACH) is applied to an existing study on relocating a gateway. The study is further improved by moving the gateway to a specific cluster based on the number or significance of the events detected. The protocol is improved so that each cluster head can communicate with a mobile gateway. The cluster heads are the only nodes that can communicate with the mobile gateway when it (the mobile gateway) is out of the cluster nodes' transmission range. Once the gateway is in range, the nodes will begin their transmission of real-time data. This alleviates the load of the nodes that would be located closest to the gateway if it were static.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.994-1005
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• 2011

In this paper, we propose a novel approach to optimize the movement of mobile sink node, called AMSP(Adaptive Mobile Sink Path) for mobile sensor network environments. Currently available studies usually suffer from unnecessary data transmission resulting from random way point approach. To address the problem, we propose a method which uses the Hilbert curve to create a path. The proposed method guarantees shorten transmission distance between the sink node and each sensor node by assigning orders of the curve according to sensor node density. Furthermore, The schedule of the sink node is informed to all of the sensing nodes so that the Duty Cycle helps the network be more energy efficient. In our experiments, the proposed method outperforms the existing works such as TTDD and CBPER by up to 80% in energy consumption.

• Journal of the Korea Society of Computer and Information
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• v.25 no.12
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• pp.195-202
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• 2020

The control system for the efficiency of resource utilization in sensor network environment based on object detection and environmental sensor requires active control function which based on sensor data acquisition and transmission functions and server's data analysis. Using active rule-based mobile agent middleware, this paper proposes a new distributed control framework that reduces the load of central sensor data server in sensor network environment by implementing remote data sensing and Zigbee-based communication with server and data analysis method of server. In addition, we implemented a power-saving system prototype using active rule-based distributed control methods that applied consumer's demand and environmental variables, and verified the validity of the proposed system through experiments and evaluations in the mobile agent middleware environment. The proposed system is a system framework that can efficiently autonomously control distributed objects in the sensor network environment, and it can be applied effectively to the development of demand response service based on optimal power control for the smart power system in the future.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.2
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• pp.163-168
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• 2008

Navigation system based on indoor location estimation is one of the core technologies in mobile robot systems. Wireless sensor network has great potential in the indoor location estimation due to its characteristics such as low power consumption, low cost, and simplicity. In this paper we present an algorithm to estimate the indoor location of mobile robot based on wireless sensor network and fuzzy modeling. ZigBee-based sensor network usually uses RSSI(Received Signal Strength Indication) values to measure the distance between two sensor nodes, which are affected by signal distortion, reflection, channel fading, and path loss. Therefore we need a proper correction method to obtain accurate distance information with RSSI. We develop the fuzzy distance models based on RSSI values and an efficient algorithm to estimate the robot location which applies to the navigation algorithm incorporating the time-varying data of environmental conditions which are received from the wireless sensor network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2029-2046
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• 2016

Energy consumption is an important index in mobile ad hoc networks. Data packet transmission increases among nodes, particularly in big data communication. However, nodes may be unable to transmit data packets because of energy over-consumption. Consequently, information may be lost and network communication may block. While opportunistic network is a kind of mobile ad hoc networks, researchers do not focus on energy consumption in opportunistic network communication. This study proposed an effective sensor energy supply scheme that can be applied in opportunistic networks. This scheme considers nodes sensor requests and communication model. In this scheme, nodes do not only accomplish energy supply in communication, but also extend communication time in opportunistic networks. Compared with the Spray and Wait algorithm and the Binary Spray and Wait algorithm in simulations, the proposed scheme extends communication time, increases data packet transmission, and accomplishes energy supply among nodes.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.2
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• pp.216-220
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• 2008

Sensor nodes in wireless network have several limitations such as lack of energy resource and network bandwidth. There are many researches to extend lifetime of sensor network and enhance availability. However, most of the previous researches didn't consider the mobile sink node. Those researches aren't suitable in the environment having mobile sinks. In this paper. we propose a scheme that reduces communication overheads and energy consumptions and improves reliability in routing path setup. Proposed scheme has excellent scalability without degrading performance in environment where many sink nodes exist and/or the network size is huge. Proposed scheme saves the energy consumption up to 70% in comparison with the previous grid-based and cluster-based protocol. As a result, proposed scheme increases the lifetime of sensor network and enhances availability of wireless sensor network.