• KIISE Transactions on Computing Practices
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• v.20 no.11
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• pp.598-603
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• 2014

In wireless sensor networks, two methods have been generally used to track continuously moving object: a user query-based method and a periodic report-based method. Although the former method generates more overhead as a result of the user queries, the former one is also an energy-efficient method that does not transfer unnecessary information. For the user query-based method, a virtual tree that consist of sensor nodes is used to perform the user query and the sensor reporting. The tree stores the information of the mobile objects, and the stored information triggers a report b the user query. However, in case of a fast-moving object, the tracking accuracy decreases as a result of the time delay of the end-to-end repeated query. In order to solve this problem, we propose a query-relay method that reduces the time delay for mobile object tracking. In the proposed method, the nodes in the tree relay the query to adjacent nodes according to the movement of mobile object that is tracked. When the query messages are relayed. The end-to-end querying time delay is reduced. and a simulation shows that our method is superior to existing ones in terms of tracking accuracy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.527-528
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• 2022

It is not easy to identify the location of mobile terminals based on drones in the mountainous area, the densely populated urban area, or the space where mobile terminals can easily move by using equipments or modules that can recognize the location of sensors or mobile terminals with LBS (Location-Based Service). However, although the performance of GPS has developed due to the development of technology, it is still widely used in position recognition systems using GPS modules in the sea and onshore, and there is much room for more utilization. Currently, most of the existing sensor networks need to send at least three location information messages to mobile terminals with location information that a plurality of mobile base stations depend on GPS. However, location recognition of mobile repeaters that maintain a certain movement speed using acceleration sensors is necessary for efficient communication network connection.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.74-90
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• 2014

Routing in mobile wireless sensor networks (MWSNs) is an extremely challenging issue due to the features of MWSNs. In this paper, we present a novel bio-inspired trusted routing protocol (B-iTRP) based on artificial immune system (AIS), ant colony optimization (ACO) and Physarum optimization (PO). For trust mechanism, B-iTRP monitors neighbors' behavior in real time and then assesses neighbors' trusts based on AIS. For routing strategy, each node proactively finds routes to the Sink based on ACO. When a backward ant is on the way to return source, it senses the energy residual and trust value of each node on the discovered route, and calculates the link trust and link energy of the route. Moreover, B-iTRP also assesses the availability of route based on PO to maintain the route table. Simulation results show how B-iTRP can achieve the effective performance compared to existing state-of-the-art algorithms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2340-2349
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• 2009

In this paper we proposed a hopping routing scheme to resolve the hot spot problem for periodic monitoring services in wireless sensor networks. Our hopping routing scheme constructs load balanced routing path, where an amount of energy consumption of all nodes in the sensor networks is predictable. Load balanced routing paths can be obtained from horizontal hopping transmission scheme which balances the load of the sensor nodes in the same area, and also from vertical hopping transmission scheme which balances the load of the sensor nodes in the other area. The direct transmission count numbers as load balancing parameter for vertical hopping transmission are derived using the energy consumption model of the sensor nodes. The experimental results show that the proposed hopping scheme resolves the hot spot problem effectively. The efficiency of hopping routing scheme is also shown by comparison with other routing scheme such as multi-hop, direct transmission and clustering.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.7
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• pp.540-544
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• 2007

Researches on Sensor Network has become much more active and is currently being applied to many different fields. However since sensor network is limited to only collecting and reporting information regarding a certain event, and requires human intervention with that given information, it is often difficult to react to an event or situation immediately and proactively. To overcome this kind of limitation, Wireless Sensor and Actor Networks (WSANs) with immediate-response Actor Nodes has been proposed which adds greater mobility and activity to exisiting sensor networks. Although WSANs shares many common grounds with sensor networks, it is difficult to apply exisiting security technologies due to the fact that WSAN contains Actor Nodes that are resource-independent and mobile. This research therefore seeks to demonstrate ways to provide security, integrity and authentication services for WSAN's secure operation, by separating networks into hierarchcial structure by each node's abilities and providing different encryption key-based secure protocols for each level of hierarchy: Pair-wise Key, Node Key, and Region Key for sensor levels, and Public Key for actor levels.

• Journal of Internet Computing and Services
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• v.9 no.6
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• pp.99-107
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• 2008

Wireless sensor networks (WSN) based on low-power technologies become important portion of ubiquitous systems. In this paper, we introduce a WSN-based welfare management system as one of the WSN applications. Especially, we implement S-MAC (Sensor Medium Access control) protocol on our system that saves both cost and power consumption, and we evaluate system performances using the TOSSIM simulator. Sensors and a small database server are placed in the house of participant, which collects and stores some environment conditions of the house. The small servers are connected to each others by wireless ad-hoc network.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.67-73
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• 2008

This paper describes a system for location tracking wireless sensor nodes in an indoor environment. The sensor reading used for the location estimation is the received signal strength indication (RSSI) as given by an RF interface. By tagging users with a mobile node and deploying a number of reference nodes at fixed position in the room, the received signal strength indicator can be used to determine the position of tagged users. The system combines Euclidean distance technique with signal strength obtained by measurement driven log-normal path loss model of 2.4 GHz wireless channel. The experimental results demonstrated the ability of this system to estimate the location with a error less than 1.3m.

• Journal of Information Processing Systems
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• v.6 no.1
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• pp.53-66
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• 2010

The energy efficiency is a key design issue to improve the lifetime of the underwater sensor networks (UWSN) consisting of sensor nodes equipped with a small battery of limited energy resource. In this paper, we apply a hexagon tessellation with an ideal cell size to deploy the underwater sensor nodes for two-dimensional UWSN. Upon this setting, we propose an enhanced hybrid transmission method that forwards data packets in a mixed transmission way based on location dependent direct transmitting or uniform multi-hop forwarding. In order to select direct transmitting or uniform multi-hop forwarding, the proposed method applies the threshold annulus that is defined as the distance between the cluster head node and the base station (BS). Our simulation results show that the proposed method enhances the energy efficiency compared with the existing multi-hop forwarding methods and hybrid transmission methods

• Journal of the Korea Society of Computer and Information
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• v.25 no.2
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• pp.105-111
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• 2020

In this paper, we propose a scheme that minimizes the energy imbalance problem of solar-powered wireless sensor network (SP-WSN) using both a mobile sink capable of wireless power transfer and an efficient clustering scheme (including cluster head election). The proposed scheme charges the cluster head using wireless power transfer from a mobile sink and mitigates the energy hotspot of the nodes nearby the head. SP-WSNs can continuously harvest energy, alleviating the energy constraints of battery-based WSN. However, if a fixed sink is used, the energy imbalance problem, which is energy consumption rate of nodes located near the sink is relatively increased, cannot be solved. Thus, recent research approaches the energy imbalance problem by using a mobile sink in SP-WSN. Meanwhile, with the development of wireless power transmission technology, a mobile sink may play a role of energy charging through wireless power transmission as well as data gathering in a WSN. Simulation results demonstrate that increase the amount of collected data by the sink using the proposed scheme.

• The KIPS Transactions:PartB
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• v.15B no.3
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• pp.219-228
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• 2008

For real-time social networking service, mobile interaction in a usable-unified-ubiquitous (U3) web service was studied. Both as a convenient mobile HCI for real-time social networks and as indexing keys to metadata information in ubiquitous web service, the multi-lingual single-character domain names (e.g. 김.net, 이.net, 가.net, ㄱ.net, ㄴ.net, ㅎ.net, ㅏ.net, ㅔ.net, ㄱ.com, ㅎ.com) are convenient mobile interfaces when searching for social information and registering information. We introduce the sketched design goals and experience of mobile interaction in Korea, Japan and China, with the implementation of real-time social networking service as an example of U3 Web service. We also introduce the possibility of extending the application to the metadata directory service in IP-USN (IP-based Ubiquitous Sensor Network) for a unified information management in the service of social networking and sensor networking.