• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.393-398
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• 2022

During the test operation period of the wind profiler prototype, radio frequency interference (RFI) contamination occurred in the spectrum. The reference of the RFI that removed the algorithm appearing in the wind profiler spectrum were investigated, and a new algorithm was developed to remove the RFI. First, it was filtered with a threshold value of 0.1 m/s of the spectral width, and the range of the number of gates with the same radial velocity was determined according to whether the beam was a vertical beam or an oblique beam. RFI contamination was removed through filtering and scanning of non-weather signals, and the continuity of wind vectors calculated from the improved spectral radial velocity was verified.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.5
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• pp.281-294
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• 2015

In order to quantitatively estimate the nonlinear destructive interaction of wave load with wind load, which is very vital for the optimal design of offshore wind energy converter, we carried out a hydraulic model test and wind tunnel test. As a substructure of offshore wind energy converter, we would deploy the monopile, which is popular due to its easiness in construction. Based on the simulation using Monte Carlo simulation using Kaimal spectrum and cross spectrum, the instantaneous maximum wind velocity is adjusted to 10 m/s. And, considering the wave conditions of the Western Sea where a pilot wind farm is planned to be constructed, $H_s=0.1m$, 0.15 m, 0.2 m is carefully chosen. It turns out that the nonlinear destructive interaction between the wind and wave loads acting on the offshore wind energy converter is more clearly visible at rough seas rather than at mild seas, which strongly support our deduction that a Large eddy, a swirling vortex developed near the bumpy water surface in the opposite direction of the wind, is the driving mechanism underlying nonlinear destructive interaction between the wind and wave loads.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.767-774
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• 2022

In this paper raw spectrum data were analyzed to suggest the moving forward of performance evaluation and quality control of wind profilers of four manufacturers operating in South Korea. For the analysis, the profile of the spectrum averaged by season and the profile of four statistical values (minimum, average, median, and maximum) calculated by Power Spectrum Density (PSD) were used. The quality of spectrum data was the best for LAP-3000, followed by YKJ3, PCL-1300, and CLC-11-H. In Cheorwon and Chupungnyeong, where PCL-1300 was installed, the variability of the spectrum due to ground clutter and non-meteorological signals was large, so ground clutter removal and signal processing such as moving average and multi-peak were required. In Gunsan and Paju, where CLC-11-H was installed, DC (Direct Current) bias and propagation folding were found, so it is necessary to remove the DC bias and limit the effective altitude for observation.

• Journal of Wind Energy
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• v.14 no.1
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• pp.14-20
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• 2023

In this study, using the commercial software Bladed developed by DNV for integrated load calculation of wind turbines, the generation of seismic waves according to soil type based on Korea's domestic regulations, and load calculation considering earthquake conditions were performed according to the IEC standard, and load in the main coordinate system of the fixed offshore wind turbine was calculated. By comparing the calculated load with the design load of the fixed offshore wind turbine, the effect of earthquake loads according to soil type on the main components of fixed offshore wind turbines was evaluated. As a result of the evaluation, when an earthquake load on a wind turbine is considered, the effect of the earthquake load is related to the natural frequency of the major components and the magnitude of the adjacent acceleration in the earthquake response spectrum, and the earthquake load differs according to soil type and may exceed the design load.

• New & Renewable Energy
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• v.3 no.4
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• pp.114-122
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• 2007

This paper addresses the measurement of structural loads on the Unison U50 wind turbine. The load measurement are carried out to determine the actual loads acting on a wind turbine. This is needed not only the certification process but also improving the technical development for prototype wind turbine. The measurement system is consists of measuring load, operating quantities and meteorological signal. All data that occur during the operating of a WT are stored the data acquisition system automatically. With using the measured data, load spectrum and equivalent load are evaluated according to IEC61400-13 "Measurement of mechanical loads".

• Wind and Structures
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• v.20 no.6
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• pp.793-810
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• 2015

Tests were conducted at the Florida International University (FIU) Wall of Wind (WOW) to investigate the susceptibility of Variable Message Signs (VMS) to wind induced vibrations due to vortex shedding and galloping instability. Large scale VMS models were tested in turbulence representative of the high frequency end of the spectrum in a simulated suburban atmospheric boundary layer. Data was measured for the $0^{\circ}$ and $45^{\circ}$ horizontal wind approach directions and vertical attack angles ranging from $-4.5^{\circ}$ to $+4.5^{\circ}$. Analysis of the power spectrum of the fluctuating lift indicated that vertical vortex oscillations could be significant for VMS with a large depth ratio attached to a structure with a low natural frequency. Analysis of the galloping test data indicated that VMS with large depth ratios, greater than about 0.5, and low natural frequency could also be subject to galloping instability.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.177-184
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• 2005

Even in moderate to low seismic regions like Korean peninsular where wind loading usually governs the structural design of a tall building, the probable structural impact of the design basis earthquake or the maximum credible earthquake on the selected structural system should be considered at least in finalizing the design. In this study, by using response spectrum analysis and time history analysis method, seismic performance evaluation was conducted for wind-designed concentrically braced steel highrise buildings. Input ensemble was normalized to be compatible with expected peak ground acceleration. The analysis results showed that wind-designed concentrically braced steel highrise buildings possess significantly increased elastic seismic capacity due to the system overstrength resulting from the wind-serviceability criterion and the width-to-thickness ratio limits on steel members. The time history analysis tended to significantly underestimated the seismic response as compared to response spectrum analysis. Further detailed studies regarding selection and scaling scheme of input ground motions is needed.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.341-344
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• 2007

This paper addresses the measurement of structural loads on the Unison U50 wind turbine. The load measurement are carried out to determine the actual loads acting on a wind turbine. This is needed not only the certification process but also improving the technical development for prototype wind turbine. The measurement system is consists of measuring load, operating quantities and meteorological signal. All data that occur during the operating of a WT are stored the data acquisition system automatically. With using the measured data, load spectrum and equivalent load are evaluated according to IEC61400-13 "Measurement of mechanical loads".

• Journal of Korean Association for Spatial Structures
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• v.21 no.1
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• pp.41-49
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• 2021

In this study the characteristics of wind pressure that are depending on the open type of retractable dome roof were analyzed according to the wind pressure coefficient and wind pressure spectrum. The analysis results showed that the open type and shape of the roof both had a significant impact on the wind pressure changing. In case of the edge to center open type, the wind pressure has not changed much because of the complex turbulence of flow and open area. On the other hand, in case of the center to edge open type, it has confirmed that wind pressure increases due to the separation of flow in windward and open area.

• Wind and Structures
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• v.14 no.4
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• pp.301-319
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• 2011

The full-scale measurements are compared with the wind tunnel test results for the long-span roof latticed spatial structure of Shenzhen Citizen Center. A direct comparison of model testing results to full-scale measurements is always desirable, not only in validating the experimental data and methods but also in providing better understanding of the physics such as Reynolds numbers and scale effects. Since the quantity and location of full-scale measurements points are different from those of the wind tunnel tests taps, the weighted proper orthogonal decomposition technique is applied to the wind pressure data obtained from the wind tunnel tests to generate a time history of wind load vector, then loads acted on all the internal nodes are obtained by interpolation technique. The nodal mean wind pressure coefficients, root-mean-square of wind pressure coefficients and wind pressure power spectrum are also calculated. The time and frequency domain characteristics of full-scale measurements wind load are analyzed based on filtered data-acquisitions. In the analysis, special attention is paid to the distributions of the mean wind pressure coefficients of center part of Shenzhen Citizen Center long-span roof spatial latticed structure. Furthermore, a brief discussion about difference between the wind pressure power spectrum from the wind tunnel experiments and that from the full-scale in-site measurements is compared. The result is important fundament of wind-induced dynamic response of long-span spatial latticed structures.