• Journal of the Korean Society for Railway
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• v.14 no.5
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• pp.416-424
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• 2011

The recent development of USN (Ubiquitous Sensor Network) technology has broadened its applications to many fields of industry. The USN technology enables the system to monitor and control the status of distributed sensor nodes based on the low-powered communications. Applying the USN in the train control domain, the operational efficiency can be enhanced, where the reliability and the safety of the system are the key challenges. This paper suggests the system design for evaluating and improving the reliability and safety of the gateway, which is a USN component that manages the radio network among the sensors and collects the information from them. For this purpose, the reliability and the level of safety integrity of a general gateway have been predicted quantitatively and the supplementary design has been proposed for the selected week points. The verification on the reliability and the safety of the improved gateway according to the related standards has been followed. With the results of the study, the applicability of USN gateway for train control systems has been reviewed.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.171-179
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• 2016

The energy consumption problem in wireless sensor networks is investigated. The problem is to expend as little energy as possible receiving and transmitting data, because of constrained battery. In this paper, in order to extend the lifetime of the network, we proposed a location-based clustering algorithm for wireless sensor network with skewed-topology. The proposed algorithm is to deploy multiple child nodes at the sink to avoid bottleneck near the sink and to save energy. Proposed algorithm can reduce control traffic overhead by creating a dynamic cluster. We have evaluated the performance of our clustering algorithm through an analysis and a simulation. We compare our algorithm's performance to the best known centralized algorithm, and demonstrate that it achieves a good performance in terms of the life time.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.4
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• pp.41-49
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• 2009

In ubiquitous sensor networks, sensor nodes can be compromised by an adversary since they are deployed in hostile environments. False sensing reports can be injected into the network through these compromised nodes, which may cause not only false alarms but also the depletion of limited energy resource in the network. In the security solutions for the filtering of false reports, the choice of a security threshold value which determines the security level is important. In the existing adaptive solutions, a newly determined threshold value is broadcasted to the whole nodes, so that extra energy resource may be consumed unnecessarily. In this paper, we propose an application of the recursive contract net protocol to determine the threshold value which can provide both energy efficiency and sufficient security level. To manage the network more efficiently, the network is hierarchically grouped, and the contract net protocol is applied to each group. Through the protocol, the threshold value determined by the base station using a fuzzy logic is applied only where the security attack occurs on.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1129-1136
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• 2022

This study leads to the shortcoming that the RSSI distance measurement method is easily affected by the external environment and the position error is large, leading to the problem of optimizing the distance values measured by the RSSI distance measurement nodes in this three-dimensional configuration environment. We proposed the CA-PSO-BP algorithm, which is an improved version of the CA-PSO algorithm. The proposed algorithm allows setting unknown nodes in WSN 3D space. In addition, since CA-PSO was applied to the BP neural network, it was possible to shorten the learning time of the BP network and improve the convergence speed of the algorithm through learning. Through the algorithm proposed in this study, it was proved that the precision of the network location can be increased significantly (15%), and significant results were obtained.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.103-112
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• 2010

In sensor networks, because sensors are deployed in an unprotected environment, they are prone to be targets of compromise attack, If the number of compromised nodes increases considerably, the key management in the network is paralyzed. In particular, compromise of Cluster Heads (CHs) in clustered sensor networks is much more threatening than that of normalsensors. Recently, rekeying schemes which update the exposed keys using the keys unknown to the compromised nodes are emerging. However, they cause some security and efficiency problems such as single group key employment in a cluster, passive eviction of compromised nodes, and excessive communication and computation overhead. In this paper, we present a proactive rekeying scheme using renewals of duster organization for clustered sensor networks. In the proposed scheme, each sensor establishes individual keys with neighbors at network boot-up time, and these keys are employed for later transmissions between sensors and their CH. By the periodic cluster reorganization, the compromised nodes are expelled from network and the individual keys employed in a cluster are changed continuously. Besides, newly elected CHs securely agree a key with sink by informing their members to sink, without exchangingany keying materials. The simulation results shows that the proposed scheme remarkably improves the confidentiality and integrity of data in spite of the increase of compromised nodes. Also, they show that the proposed scheme exploits the precious energy resource more efficiently than SHELL.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.91-96
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• 2014

Since the sensors of Internet of Things (IOT) collect various data, the lifetime of sensor network is very important and the data should be aggregated efficiently. The contiguous collection by the certain sensors occurs an excessive battery consumption and successive transmission of same value of data should be avoided. To solve these things, we propose an weight-based cluster head replacement method that divides whole network into several grids and cluster head is selected by remaining energy, density of alive sensors and location of sensor. The aim of algorithm maximizes the lifetime of network. Our simulation results shows that the proposed method is very simple as well as balances energy consumption.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.217-220
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• 2014

Wireless sensor network（WSN） consists by a large number of low-cost micro-sensor nodes, collaborate to achieve the perception of information collection, processing and transmission tasks in deployment area. It can be widely used in national defense, intelligent transportation, medical care, environmental monitoring, precision agriculture, and industrial automation and many other areas. One of the key technologies of sensor networks is the data maintenance management technology. In this paper we analyze the data management technology of wireless sensor network and pointed their problems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.233-240
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• 2011

A field server was developed by using ubiquitous sensor network technology to monitor the abrupt weather variation in local or mountain area. The data transmissions between deployed field servers in local terrain are very important technology in disaster prevention monitoring system. Weather related information such as temperature, humidity, illumination, atmospheric pressure, dew point and meteorological data are collected from the designated field at a regular interval. The received information from the multiple sensors located at the sensor field is used flooding routing protocol transmission techniques and the sensing data is transferred to gateway through multi-hop method. Telosb sensor node are programmed by nesC language in TinyOS platform to monitor the weather parameters of the local terrain.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.344-347
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• 2011

Unlike a terrestrial wireless sensor network which uses radio waves, UWASN(Underwater Acoustic Sensor Network) relies on acoustic waves. There are lots of ongoing researches for long latency and limited bandwidth of underwater sensor network by using acoustic wave. Packets transferred by node often colide in underwater sensor network due to long latency. To solve this kind of problem, in general, Back-off scheme which is used in wireless network is used. However, fixed Slot-time according to node allocation generates useless time delay, and this lowers network performance. In this thesis, active setting technique of Slot-time is proposed, and applied for already studied MAC protocol. At the conclusion, it was proved that the MAC protocol using the proposed scheme has better performance than existing MAC protocol as a result comparison.

• Journal of Internet Computing and Services
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• v.15 no.5
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• pp.1-7
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• 2014

WireWireless sensor networks(WSNs) are generally comprised of densely deployed sensor nodes, which causes highly redundant sensor data transmission and energy waste. Many studies have focused on energy saving in WSNs. However, delay problem also should be taken into consideration for mission-critical applications. In this paper, we propose a BISA (Bio-Inspired Scheduling Algorithm) to reduce the energy consumption and delay for WSNs inspired by biological systems. BISA investigates energy-efficient routing path and minimizes the energy consumption and delay using multi-channel for data transmission. Through simulations, we observe that the BISA archives energy efficiency and delay guarantees.