• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.412-413
• /
• 2005

This paper describes resonant frequency of the structural behavior of micro-cantilever beam simulated by FEM (Finite Element Method). The resonant characteristics and the sensitivity of cantilever-shaped SOI resonant were measured for the application of chemical sensor. The resonant frequency of the fabricated micro-cantilever system was found to be 5.59kHz when the size of cantilever is $500{\mu}m$ long, $100{\mu}m$ wide and $1{\mu}m$ thick. Generation of resonant frequency measured by Modal Analysis is resulted in length of cantilever. The length was found to be a dominant factor for the selection of required resonant frequency range. On the other side, the width had influenced very little on either the magnitude of resonant frequency or the sensitivity.

• Journal of Information Processing Systems
• /
• v.17 no.6
• /
• pp.1097-1114
• /
• 2021

The primary objective of this work was to discover a solution for the survival of people in an emergency flood. The geographical information was obtained from remote sensing techniques. Through helpline numbers, people who are in need request support. Although, it cannot be ensured that all the people will acquire the facility. A proper link is required to communicate with people who are at risk in affected areas. Mobile sensor networks with field-programmable gate array (FPGA) self-configurable radios were deployed in damaged areas for communication. Ad-hoc networks do not have a centralized structure. All the mobile nodes deploy a temporary structure and they act as a base station. The mobile nodes are involved in searching the spectrum for channel utilization for better communication. FPGA-based techniques ensure seamless communication for the survivors. Timely help will increase the survival rate. The received signal strength is a vital factor for communication. Cognitive radio ensures channel utilization in an effective manner which results in better signal strength reception. Frequency band selection was carried out with the help of the GRA-MADM method. In this study, an analysis of signal strength for different mobile sensor nodes was performed. FPGA-based implementation showed enhanced outcomes compared to software-based algorithms.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2011.04a
• /
• pp.158-159
• /
• 2011

Energy efficiency in wireless sensor networks (WSNs) is one significant factor that needs to be considered when making any designs or doing any enhancements on the communication protocol stack. In WSNs using traditional geographic routing, when a sensor node receives a data packet that needs to be transmitted to the sink, it will forward the packet to the neighbor node which is closest to the sink. The traditional geographic routing assumes that the link quality is always 100%. This may cause a bad result as per which we waste too many energy for retransmissions between the two nodes. Thus, the problem here is how to select such node as forwarder at most efficiently in the aspect of both energy consumption and the distance toward the destination. The better node we choose, the more energy we can conserve for the whole network. In this paper, we propose a next-hop forwarding selection metric, called Energy Consumption for Transmission (ECT), which can resolve the above problem in the best way.

• Proceedings of the Korean Information Science Society Conference
• /
• 2011.06d
• /
• pp.267-268
• /
• 2011

Recent research activities in cooperative communication focus on achieving energy efficiency and reliability. Relay selection strategy for cooperative communication improves the performance significantly. However, due to imbalance consumption of power, network might die earlier and more than 90% energy remains unused. In this paper, we provide a framework of an energy-efficient medium access control protocol that minimizes these problems and improves energy efficiency.

• Nuclear Engineering and Technology
• /
• v.37 no.2
• /
• pp.177-184
• /
• 2005

The Multivariate State Estimation Technique (MSET) is being used in Nuclear Power Plants for sensor and equipment condition monitoring. This paper presents the use of regularization methods for optimizing MSET's predictive performance. The techniques are applied to a simulated data set and a data set obtained from a nuclear power plant currently implementing empirical, on-line, equipment condition monitoring techniques. The results show that regularization greatly enhances the predictive performance. Additionally, the selection of prototype vectors is investigated and a local modeling method is presented that can be applied when computational speed is desired.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.1393-1395
• /
• 2003

In this research, we presented a data integration, which integrates ultra high resolution images and complementary data for 3D building reconstruction. In our method, as the ultra high resolution image, Three Line Sensor (TLS) images are used in combination with 2D digital maps, DSMs and both of them. Reconstructed 3D buildings, correctness rate and the accuracy of results were presented. As a result, optimized combination scheme of data sets , sensors and methods was proposed.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.855-856
• /
• 2011

• Smart Structures and Systems
• /
• v.21 no.4
• /
• pp.407-420
• /
• 2018

In structural health monitoring, it is meaningful to comprehensively utilize accelerometers and strain gauges to obtain the modal information of a structure. In this paper, a modal estimation theory is proposed, in which the displacement modes of the locations without accelerometers can be estimated by the strain modes of selected strain gauge measurements. A two-stage sensor placement method, in which strain gauges are placed together with triaxial accelerometers to obtain more structural displacement mode information, is proposed. In stage one, the initial accelerometer locations are determined through the combined use of the modal assurance criterion and the redundancy information. Due to various practical factors, however, accelerometers cannot be placed at some of the initial accelerometer locations; the displacement mode information of these locations are still in need and the locations without accelerometers are defined as estimated locations. In stage two, the displacement modes of the estimated locations are estimated based on the strain modes of the strain gauge locations, and the quality of the estimation is seen as a criterion to guide the selection of the strain gauge locations. Instead of simply placing a strain gauge at the midpoint of each beam element, the influence of different candidate strain gauge positions on the estimation of displacement modes is also studied. Finally, the modal assurance criterion is utilized to evaluate the performance of the obtained multitype sensor placement. A bridge benchmark structure is used for a numerical investigation to demonstrate the effectiveness of the proposed multitype sensor placement method.

• Journal of Korea Multimedia Society
• /
• v.14 no.10
• /
• pp.1287-1302
• /
• 2011

Clustering protocol that is used in wireless sensor network is an efficient method that extends the lifetime of the network. However, when this method is applied to an environment in which collected data of the sensor node easily overlap, sensor nodes unnecessarily consumes energy. In the case of clustering technique that uses a threshold, the lifetime of the network is extended but the degree of accuracy of collected data is low. Therefore it is hard to trust the data and improvement is needed. In addition, it is hard for the clustering protocol that uses multi-hop transmission to normally collect data because the selection of a cluster head node occurs at random and therefore the link of nodes is often disconnected. Accordingly this paper suggested a cluster-formation algorithm that reduces unnecessary energy consumption and that works with an alleviated link disconnection. According to the result of performance analysis, the suggested method lets the nodes consume less energy than the existing clustering method and the transmission efficiency is increased and the entire lifetime is prolonged by about 30%.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.1
• /
• pp.87-93
• /
• 2013

The selection of the temperature sensor in a cryogenic system depends on the temperature range, shape, and accuracy. An accurate temperature sensor is essential for improving the reliability of an experiment. We have developed a calibration system for cryogenic temperature sensors using a two-stage cryocooler. To reduce the heat load, a thermal shield is installed at the first stage with multiple layer insulation (MLI). We have also developed a sensor holder for calibrating more than 20 sensors simultaneously in order to save time and reduce costs. This system can calibrate sensors at variable temperatures via temperature control using a heater. In this paper, we present the design and fabrication of the temperature sensor calibration system and a representative experimental result.