• Journal of Ocean Engineering and Technology
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• v.24 no.6
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• pp.7-15
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• 2010

Analyses of wind wave characteristics near the Korean marginal seas were performed in 2008 and 2009 by comparisons of an operational wind wave forecast model and ocean buoy data. In order to evaluate the model performance, its results were compared with the observed data from an ocean buoy. The model used in this study was very good at predicting the characteristics of wind waves near the Korean Peninsula, with correlation coefficients between the model and observations of over 0.8. The averaged Root Mean Square Error (RMSE) for 48 hrs of forecasting between the modeled and observed waves and storm surges/tide were 0.540 m and 0.609 m in 2008 and 2009, respectively. In the spatial and seasonal analysis of wind waves, long waves were found in July and September at the southern coast of Korea in 2008, while in 2009 long waves were found in the winter season at the eastern coast of Korea. Simulated significant wave heights showed evident variations caused by Typhoons in the summer season. When Typhoons Kalmaegi and Morakot in 2008 and 2009 approached to Korean Peninsula, the accuracy of the model predictions was good compared to the annual mean value.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.37.1-37.1
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• 2011

A floating wind turbine dynamic simulation program, 'WindHydro', is newly developed. In order to investigate the characteristics of the program, a series of loading cases are simulated such as (1) wind only case, (2) free decay cases with initial displacement, (3) wave only case (4) wind and wave case. The simulations are carried out for the 5-MW OC3-Hywind model which has a spar buoy and catenary mooring lines. As a result, the reliability of WindHydro is verified in most viewpoints although additional study is still necessary to clear out some uncertainty of the program.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.5
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• pp.1013-1025
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• 2014

Marine meterological characteristics off the coast in the East Sea between 2006 and 2013 were investigated by comparing the high wind-wave alert and moored-measured significant wave high. Monthly and yearly variations of the high wind-wave alert duration off the coast in the central part of the East Sea are correlated with those of the significant wave height measurement with their minima in June and 2008 and maxima in December and 2012. Both the high wind-wave alert duration and significant wave height increase remarkably during 2010-2013 when compared with during 2006-2009. The remarkable increase, occurring dominantly in December, seems to be related with Arctic oscillation variability. However, the comparisons reveal that only about a half of high wind-wave alerts satisfy the criteria for issuing the high wind-wave alert. To issue the high wind-wave alert, the wind speed at the sea should exceed 14 m/s or the significant wave height should be higher than 3 m. The high wind-wave alerts unsatisfying the significant wave height criteria are issued mainly during spring and summer. These results imply that additional surface buoy moorings in the open basin of the East Sea are necessary for more accurate issue of the high wind-wave alert.

• Atmosphere
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• v.19 no.1
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• pp.93-106
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• 2009

Analysis has been made on the wind wave characteristics in terms of significant wave height ($H_s$) near the Korean marginal seas in the 2006 - 2007 year using the third generation wave model, WAVEWATCH - III model. In order to evaluate its performance, its results were compared with the observed data using KMA ocean buoy. The two year average RMSE between modeled and observed Hs shows reasonably small value of about 0.37 m. The accuracy of predicted values in the year 2007 is increased mainly due to finer model grid size and better accurate wind field. The model used in this study predicts very well the characteristics ($H_s$) of wind waves near the Korean Peninsular. Simulated monthly wind waves show the evident seasonal variations due to Typhoons in summer season. When Typhoons approach to Korean Peninsular, the accuracy of wind waves predictions is lower than that of annual mean value.

• Ocean Science Journal
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• v.40 no.4
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• pp.213-220
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• 2005

In this paper, image processing technique that reduces video images of buoy motion to yield time series of image coordinates of buoy objects will be investigated. The buoy motion images are noisy due to time-varying brightness as well as non-uniform background illumination. The occurrence of boats, wakes, and wind-induced white caps interferes significantly in recognition of buoy objects. Thus, semi-automated procedures consisting of object recognition and image measurement aspects will be conducted. These offer more satisfactory results than a manual process. Spectral analysis shows that the image coordinates of buoy objects represent wave motion well, indicating its usefulness in the analysis of wave characteristics.

• Journal of Navigation and Port Research
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• v.46 no.1
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• pp.11-17
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• 2022

The high wind wave alert has a great impact on ships and maritime service workers navigating in the vicinity of Korea. This study aims to evaluate the appropriateness of the high wind wave alert by comparing and analyzing the observation data of major marine meteorological buoys with the high wind wave alerts in the coastal sea and offshore of the West Sea, South Sea, and the East Sea announced by the Korea Meteorological Administration for the past 11 years(2010-2020). As a result of comparing the daily, monthly, and annual statistics of the high wind wave alert and marine meteorological buoy observation data for each sea area by annual, monthly, and seasonal average, the accuracy of high wind wave alerts was very low across the entire sea area. In particular, it was analyzed that the accuracy in the coastal sea of the South Sea and Jejudo was the lowest in winter. It was confirmed that the accuracy of marine weather forecasts and alerts needs to be improved when considering the effects of the high wind wave alerts on fishing vessels, passenger ships operations and tourism, and marine leisure activities.

• Ocean Systems Engineering
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• v.12 no.4
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• pp.413-437
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• 2022

An innovative concept for wet-transportation and stepwise installation of mono-bucket foundation for 15 MW offshore wind turbine is proposed. Case studies for two different mono-bucket and wrap-buoy dimensions are conducted and their hydrostatic and hydrodynamic performances are compared for both wet-towing and lowering operations. The intact stability and transient responses are analyzed in detail for various stages of lowering operation. Wave-induced motion statistics during wet tow in sea state 4 (highest operational window) are checked. The proposed concept is found to be feasible and can be an alternative cost-effective solution without using heavy-lift crane vessel in practice.

• Journal of Environmental Science International
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• v.15 no.5
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• pp.417-430
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• 2006

We focused on improvement in simulation of wind fields for the complex coastal area. Local Analysis and Prediction System(LAPS) was used as a data assimilation method to improve initial conditions. Case studies of different LAPS inputs were performed to compare improvement of wind fields. Five cases have been employed : I) non data assimilation, II) all available data, III) AWS, buoy, QuikSCAT, IV) AWS, buoy, wind profiler, V) AWS, buoy, AMEDAS. Data assimilation can supplement insufficiency of the mesoscale model which does not represent detailed terrain effect and small scale atmospheric flow fields. Result assimilated all available data showed a good agreement to the observations rather than other cases and estimated veil the local meteorological characteristics including sea breeze and up-slope winds. Result using wind profiler data was the next best thing. This implies that data assimilation with many high-resolution sounding data could contribute to the improvements of good initial condition in the complex coastal area. As a result, these indicated that effective data assimilation process and application of the selective LAPS inputs played an important role in simulating wind fields accurately in a complex area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.3
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• pp.111-118
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• 2004

An ocean buoy was deployed 10 km off Donghae city, Korea at a depth of 130 m to measure meteorological (air pressure, air temperature, wind speed, wind gust, wind direction, relative humidity) and oceanographic data (water properties and currents in the whole column) in real-time. The buoy recorded a maximum wind gust of 25 m/s (10 minutes' average speed of 20 m/s) and a minimum air pressure of 980 hPa when the eye of typhoon Maemi passed by near the Uljin city, Korea at 03:00 on 13 September 2003. The wave height reached maximum of 9 m with the significant wave height of 4 m at 04:00 (1 hour after the passage of Maemi). The currents measured near the surface reached up to about 100 cm/s at 13:00 (10 hours after the passage of Maemi). The mixed layer (high temperature and low salinity) thickness, which was accompanied by strong southward current, gradually increased from 20 m to 40 m during the 10 hours. A simple two layer model for the response to an impulsive alongshore wind over an uniformly sloping bottom developed by Csanady (1984) showed reasonable estimates of alongshore and offshore currents and interface displacement for the condition of typhoon Maemi at the buoy position (x=8.15 km) during the 10 hours.

• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.29-34
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• 2010

Wind speed and wind direction are usually taken using two parameters: wind speed and wind direction. This paper studies the average wind speed and direction calculation methods. The paper first introduces to basic wind's knowledge, and then presents several methods in calculating average wind speed and direction. Lastly some graphs are plotted base on these computational methods and the implementation of these methods in an actual buoy system.