• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.4
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• pp.117-126
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• 2009

The recent interest in sensor networks has led to a number of routing schemes that use the limited resources available at sensor nodes more efficiently. These schemes typically try to find the minimum energy path to optimize energy usage at a node. Some schemes, however, are prone to unbalance of the traffic and energy. To solve this problem, we propose a novel solution: a gradient-field approach which takes account of the minimum cost data delivery, energy consumption balancing, and traffic equalization. We also modify the backoff-based cost field setup algorithm to establish our gradient-field based sensor network and give the algorithm. Simulation results show that the overhead of routing establishment obtained by our algorithm is much less than the one obtained by Flooding. What's more, our approach guarantees the basic Quality of Service (QoS) without extra spending.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.503-504
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• 2007

The most Important thing in Sensor Network Design is a Energy Efficiency. Limited sources of Sensor Mote tan occur merging of Protocol. In this paper, we proposed Cross Layer Protocol for Energy Efficienty. The proposed protocol can increase the network life time using multi hop transmission. sensor network should use multi hop communication and small radius because radio in wireless communication is the most spendable thing in sensor network.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.946-949
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• 2004

It is necessary to detect the tilt angle for control or monitoring of various systems such as ship, aircraft recreation facilities etc as well as bridge or building systems. However the electronic liquid charge type tilt sensor which is one of typical tilt sensor has many problems. Those are remarkably slow response time and limited mounting condition because or liquid viscosity coefficient and inertia etc. In this study we propose a tilt angle instrumentation method using piezoelectricity acceleration sensor. The method can he applied on moving mount We verified the validity of the method through experiment.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.146-154
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• 2019

An improved principal component analysis (PCA) method is applied for sensor fault detection and isolation (FDI) in a nuclear power plant (NPP) in this paper. Data pre-processing and false alarm reducing methods are combined with general PCA method to improve the model performance in practice. In data pre-processing, singular points and random fluctuations in the original data are eliminated with various techniques respectively. In fault detecting, a statistics-based method is proposed to reduce the false alarms of $T^2$ and Q statistics. Finally, the effects of the proposed data pre-processing and false alarm reducing techniques are evaluated with sensor measurements from a real NPP. They are proved to be greatly beneficial to the improvement on the reliability and stability of PCA model. Meanwhile various sensor faults are imposed to normal measurements to test the FDI ability of the PCA model. Simulation results show that the proposed PCA model presents favorable performance on the FDI of sensors no matter with major or small failures.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.6B
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• pp.233-248
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• 2008

Advances in electronics and wireless communication technologies have enabled the development of large-scale wireless sensor networks (WSNs). There are numerous applications for wireless sensor networks, and security is vital for many of them. However, WSNs suffer from many constraints, including low computation capability, small memory, limited energy resources, susceptibility to physical capture, and the lack of infrastructure, all of which impose unique security challenges and make innovative approaches desirable. In this paper, we present a survey on security issues in wireless sensor networks. We address several network models for security protocols in WSNs, and explore the state of the art in research on the key distribution and management schemes, typical attacks and corresponding countermeasures, entity and message authentication protocols, security data aggregation, and privacy. In addition, we discuss some directions of future work.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.5
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• pp.666-669
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• 2020

Energy harvesting sensor networks have the ability to collect energy from the environment to overcome the power limitations of traditional sensor networks. The sensor network, which has a limited transmission range, delivers data to the destination node through a multi-hop method. The routing protocol should consider the power situation of nodes, which is determined by the residual power and energy harvesting rate. At this time, if only considering the magnitude of the power, power imbalance can occur among nodes and it can induce instantaneous power shortages and reduction of network lifetime. In this paper, we designed a routing protocol that considers the balance of power as well as the residual power and energy harvesting rate.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.51.3-51.3
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• 2010

Due to the recent public awareness of global warming and sustainable economic growth, there has been a growing interest in alternative clean energy sources. Hydrogen is considered as a clean fuel for the next generation. One of the technical challenges related to the use of hydrogen is safe monitoring of the hydrogen leak during separation, purification and transportation. For detecting various gases, chemiresistor-type gas sensors have been widely studied and used due to their well-established detection scheme and low cost. However, it is known that many of them have the limited sensitivity and slow response time, when used at low temperature conditions. In our work, a sensor based on Schottky barriers at the electrode/sensing material interface showed promising results that can be utilized for developing fast and highly sensitive gas sensors. Our hydrogen sensor was designed and fabricated based on indium oxide (In2O3)-doped tin oxide (SnO2) semiconductor nanoparticles with platinum (Pt) nanoclusters in combination with interdigitated electrodes. The sensor showed the sensitivity as high as $10^7%$ (Rair/Rgas) and the detection limit as low as 30 ppm. The sensor characteristics could be obtained via optimized materials synthesis route and sensor electrode design. Not only the contribution of electrical resistance from the film itself but also the interfacial effect was identified as an important factor that contribute significantly to the overall sensor characteristics. This promises the applicability of the developed sensor for monitoring hydrogen leak at room temperature.

• Journal of Communications and Networks
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• v.11 no.1
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• pp.57-71
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• 2009

Networking together hundreds or thousands of cheap sensor nodes allows users to accurately monitor a remote environment by intelligently combining the data from the individual nodes. As sensor nodes are typically battery operated, it is important to efficiently use the limited energy of the nodes to extend the lifetime of the wireless sensor network (WSN). One of the fundamental issues in WSNs is the coverage problem. In this paper, the border coverage problem in WSNs is rigorously analyzed. Most existing results related to the coverage problem in wireless sensor networks focused on planar networks; however, three dimensional (3D) modeling of the sensor network would reflect more accurately real-life situations. Unlike previous works in this area, we provide distributed algorithms that allow the selection and activation of an optimal border cover for both 2D and 3D regions of interest. We also provide self-healing algorithms as an optimization to our border coverage algorithms which allow the sensor network to adaptively reconfigure and repair itself in order to improve its own performance. Border coverage is crucial for optimizing sensor placement for intrusion detection and a number of other practical applications.

• Journal of Korea Multimedia Society
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• v.20 no.4
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• pp.640-648
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• 2017

Sensors have limited resources in sensor networks, so efficient use of energy is important. In order to use the energy of the sensor node efficiently, researches applying mobile sink to the sensor network have been actively carried out. The sink node moves the sensor network, collects data from each sensor node, which spread the energy concentrated around the sink node, thereby extending the entire life cycle of the network. But, when the sink node moves, it requires a reset of the data transmission path, which causes a lot of control messages and delays. In this paper, we propose a CMS(Cluster-based Mobile Sink) method to support the movement of mobile sink in a cluster sensor environment. The proposed scheme minimizes an amount of control messages without resetting the routing paths of entire sensor networks by supporting the sink mobility path using the neighbor cluster list. And, it simplifies the routing path setup process by setting a single hop path between clusters without a gateway. The experiment results show that the proposed scheme has superior energy efficiency in processing and network structure, compared with existing clustering and mesh routing protocols.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.733-736
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• 2013

The sensor network technology for core technology of ubiquitous computing is in the spotlight recently, the research on sensor network is proceeding actively which is composed many different sensor node. The major traffic patterns of plenty of sensor networks are composed of collecting types of single directional data, which is transmitting packets from several sensor nodes to sink node. One of the important condition for design of sensor node is to extend for network life which is to minimize power-consumption under the limited resources of sensor network. In this paper analysis used routing protocols using the network simulation that was used second level cluster structure to reduce delay and power-consumption of sensor node.