• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1362-1376
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• 2016

A cloud computing system can be characterized by the provision of resources in the form of services to third parties on a leased, usage-based basis, as well as the private infrastructures maintained and utilized by individual organizations. To attain the desired reliability and energy efficiency in a cloud data center, trade-offs need to be carried out between system performance and power consumption. Resolving these conflicting goals is often the major challenge encountered in the design of optimization strategies for cloud data centers. The work presented in this paper is directed towards the development of an Energy-efficient and Performance-aware Cloud System equipped with strategies for dynamic switching of optimization approach. Moreover, a platform is also provided for the deployment of a Wind Farm CMS (Condition Monitoring System) which allows ubiquitous access. Due to the geographically-dispersed nature of wind farms, the CMS can take advantage of the cloud's highly scalable architecture in order to keep a reliable and efficient operation capable of handling multiple simultaneous users and huge amount of monitoring data. Using the proposed cloud architecture, a Wind Farm CMS is deployed in a virtual platform to monitor and evaluate the aging conditions of the turbine's major components in concurrent, yet isolated working environments.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.209-214
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• 2011

A method to detect rotor mass imbalance, which is one of the typical faults of wind turbine, is presented for effective condition monitoring of wind turbine. Dynamic analysis for a three-bladed horizontal-axis wind turbine was carried out with adding mass to a blade for inflicting the rotor mass imbalance. It has been found that the added mass induce a resulting centrifugal force to nacelle and this leads to a transverse (relative to the rotor axis) oscillation of the nacelle. It has been also found that the amplitude of the oscillation is almost linearly increased as the added mass is increased.

• Wind and Structures
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• v.37 no.5
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• pp.383-397
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• 2023

In the Structural Health Monitoring (SHM) system of civil engineering, data missing inevitably occurs during the data acquisition and transmission process, which brings great difficulties to data analysis and poses challenges to structural health monitoring. In this paper, Convolution Neural Network (CNN) is used to recover the nonstationary wind speed data missing randomly at sampling points. Given the technical constraints and financial implications, field monitoring data samples are often insufficient to train a deep learning model for the task at hand. Thus, simulation combined transfer learning strategy is proposed to address issues of overfitting and instability of the deep learning model caused by the paucity of training samples. According to a portion of target data samples, a substantial quantity of simulated data consistent with the characteristics of target data can be obtained by nonstationary wind-field simulation and are subsequently deployed for training an auxiliary CNN model. Afterwards, parameters of the pretrained auxiliary model are transferred to the target model as initial parameters, greatly enhancing training efficiency for the target task. Simulation synergy strategy effectively promotes the accuracy and stability of the target model to a great extent. Finally, the structural dynamic response analysis verifies the efficiency of the simulation synergy strategy.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.276-289
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• 2013

In developing offshore wind farms, many environmental issues arise because of the concentration on supply demand and economic logic. Accordingly, community conflict is induced. Especially, recent studies regarding the capacity and location of offshore wind development have been conducted considering wind states and ocean conditions, etc. of coastal seas in Republic of Korea. Nevertheless, studies on the impact of marine environments and ecosystems are very limited so far. Environmental monitoring that follows development projects has been actively done in the offshore wind farms in many developed European countries. In contrast, there is no domestic monitoring data regarding environmental impacts caused by installing and operating offshore wind power. Therefore, the environmental impacts under construction and operation phases as well as the guidelines in the stage of environmental impact assessment suited for domestic coastal seas are well presented in this study by analyzing monitoring cases and references of overseas offshore wind farm. For this reason, this research is ultimately aimed at minimizing the environmental impact in offshore wind farm development and thus simplify administrative procedures in Korea.

• Wind and Structures
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• v.8 no.3
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• pp.179-196
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• 2005

This paper describes the application of a wireless data acquisition system to monitor wind pressures and velocities with absolute pressure sensors and an anemometer. The system was developed for future deployment, as part of a research effort currently underway to instrument coastal homes in Florida to monitor roof wind pressures during hurricanes. The proposed wireless system will replace the current system that involves a large amount of hardwired connections from the sensors to the data processing unit that requires labor intensive wiring and preparation of the home. The paper describes comparison studies and field tests to assess the performance of the system. The new system offers the advantages of light hardware, ease of installation, capacity for 48 hours of continuous data acquisition, good frequency and amplitude responses, and a relatively simple maintenance. However, the tests also show that the shape of the shell that has been previously used to protect the sensors might interfere with the proper measurement of the pressures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.2 s.107
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• pp.124-131
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• 2006

This study introduces an environmental noise evaluation procedure for wind turbines(W/T) and the evaluation result of a 750 kW wind turbine(W/T) system. Test and evaluation are performed according to the international standard IEC 61400-11 on J48 W/T which is under operation in Daekwanryung W/T test site. With the meteorological data and W/T operational data, noise data are monitored and analysed. An integrated monitoring system is constructed in the test site and is utilized for the evaluation. From the measured noise data, acoustic power level, directivity and tonality of the W/T are estimated under the wind speeds required fly the International standard. The purpose of the study is to establish an W/T noise evaluating system satisfying the international standard and to obtain noise data for home made 750 kW W/T.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11b
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• pp.33-37
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• 2004

Photovoltaic energy and wind energy are highly dependent on the season, time and extremely intermittent energy sources. Because of these reasons, in view of the reliability the photovoltaic and the wind power generation system have many problems(energy conversion, energy storage, load control etc.) comparing with conventional power plant. In order to solve these existing problems, hybrid generation system composed of photovoltaic(500W) and wind power system(400W) was suggested But, hybrid generation system cannot always generate stable output due to the varying weather condition So, the auxiliary power compensation unit that uses elastic energy of spiral spring was added to hybrid generation system for the present study. It was partly confirmed that hybrid generation system was generated a stable outputs by spiral spring was continuously provided to load.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.1
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• pp.27-33
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• 2013

Nowadays, the utilization of renewable energy sources like wind energy is considered one of the most effective means of generating massive amounts of electricity. This is evident in the rapid increase of wind farms all over the world which comprise a huge number of wind turbines. However, the drawback of utilizing wind turbines is that it requires maintenance, which could be a costly operation. To keep the wind turbines in pristine condition so as to reduce downtime, the implementation of CMS (Condition Monitoring System) and FDS (Fault Detection System) is mandatory. The efficiency and accuracy of these systems are crucial in deciding when to carry out a maintenance process. In this paper, a fault detection system based on intelligent clustering method is proposed. Using SCADA data, the clustering model was trained and evaluated for its accuracy through rigorous simulations. Results show that the proposed approach is able to accurately detect the deteriorating condition of a wind turbine as it nears a downtime period.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.5 s.248
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• pp.560-567
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• 2006

The exact load measurements for the mechanical parts of a wind turbine are important step both fur the evaluation of a specific wind turbine design and for a certification process. A common method for a mechanical load measurement is using a strain gauge sensing. Two main problems ought to be answered in order for this method to be applied to the wind turbine project. These are strain gauge calibration and non-contact signal transmission from the strain gauge output to a load monitoring system. This paper suggests reliable solutions fer these two problems. A Bluetooth, a short range wireless data communication technology, is used to solve the second problem. The first one, the strain gauge calibration methodology for a load measurement in a wind turbine application, is fully explained in this paper. Various mechanical loadings for a strain gauge calibration in a wind turbine load measurement are introduced and analyzed. Initial experimental results which are obtained from a 1 kW small size wind turbine are analyzed, and the uncertainty problem in estimating mechanical loads using a calibration matrix is fully covered in this paper.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.56-64
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• 2013

The wind resistant capacity of bridges with a span of less than 200m is typically evaluated by Wind Resistant Design Manual for Highway Bridges in Japan. Also, the first vertical frequency plays an important role in the evaluation of their aerodynamic performance. An unexpected vortex-induced vibration of Nielsen arch bridge with span of 183m designed by this manual has been measured by monitoring system during typhoon. The amplitude of vibrations was about 2 times than the allowable vibration displacement. This paper presents the feature of vortex-induced vibration of this Nielsen arch bridge based on measured wind velocity, wind direction, and responses at midspan of main girder. From the result of FFT, the $1^{st}$ mode shape of the bridge is antisymmetric and the $2^{nd}$ is symmetric. Also, the dominant vibration of the bridge is the $2^{nd}$ vertical mode. According to these results, the $2^{nd}$ vertical vibration mode of this Nielsen arch bridge is prior to the first for the estimation of wind resistance capacity.