• Journal of Korean Society of Disaster and Security
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• v.10 no.2
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• pp.21-28
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• 2017

Wind turbulence data is required for engineering calculations of gust speeds, mean and fluctuating loading. Spectral densities are required as input data for methods used in assessing dynamic response. This study is concerned with the estimation of daily instantaneous maximum wind velocity in the meteorological major cities (selected each 6 points) during the yearly 1987-2016.12.1. The purpose of this paper is to present the power spectral densities of the daily instantaneous maximum wind velocity. In the processes of analysis, used observations data obtained at Korea Meteorological Adminstration(KMA), it is assumed as a random processes. From the analysis results, in the paper estimated power spectral densities function(Blunt model) shows a very closed with von Karman and Solari's spectrum models.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.2
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• pp.4089-4095
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• 1976

The safety of shore structure including the sea dipe is largely affected by typhoon. Accordingly it is desirable to analize the typhoon and determine the wind direction and velocity for use in planning and design of the structure. This method was adopted for the design of the Yong San Gang Estuary Dam. A comparative study of the results of typhoon analysis with the meteorological data obtained through actual observation is summarized as follows; (1) 62% of the typhoons occur during May to June in a year, and 62% of the typhoons which have an influence on the Korean peninsula, especially the proposed estuary dam fsite, proceed eastward through the zone in lat. 36$^{\circ}$-37$^{\circ}$N. Such typhoons occur two to three times a year on the average. (2) Data on typhoon "SARL" were used as a model case in designing the estuary dam, where it was proved that a southwesterly wind had a maximum velocity of 30m/sec in case r=150km, ${\alpha}$=120$^{\circ}$. Within the range of 22$^{\circ}$30'on the right and left side of the fetch line of the estuary dam, the wind direction varied SSW\longrightarrowSW\longrightarrowWSW, and the wind velocity varied 29m/sec\longrightarrow30m/sec\longrightarrow125m/sec. Such phenomemum lasted for five hours. (3) An analysis of data obtained during 44 years at Mok Po Meteorological Station shows that a wind with a velocity of some 25m/sec occurred twelve times in the S-direction and two times in the SW-direction, while that with a velocity of 30m/sec occurred three times in the S-direction, three times in the SSW-direction and one time in the SW-direction. The wind which had an influence on the estuary dam had a direction of SSW\longrightarrowSW\longrightarrowWSW and a velocity of min. 30m/sec. Actually, a wind with a max. velocity of 31.3m/sec occurred in the SSW-direction on March 15 and 16, 1956 where the mean velocity during two hours was 28m/sec and that during four hours was 24.6m/sec. (4) The data obtained through actual observation show that when the velocity is low, the wind with a fixed direction lasts long, and when the velocity is high, it is short-lived. It is difficult to determine the velocity of a wind which blows in a fixed direction for consecutive two or four hours. Therefore, the values obtained through typhoon analysis are larger that those obtained through actual observation, and hence, it is resonable to use the analyzed valuse for design of the estuary dam and shore structures. (5) The greatest effect was had on the estuary dam when typhoon was proceeding at a velocity of 29.71m/sec in the direction of ${\alpha}$=120$^{\circ}$(SW) at a point of R=150km from the center of the typhoon.

• Wind and Structures
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• v.15 no.1
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• pp.1-15
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• 2012

High-resolution wind data were acquired from a 100-m high offshore tower during the passage of Typhoon Hagupit in September, 2008. The meteorological tower was equipped with an ultrasonic anemometer and a number of cup anemometers at heights between 10 and 100 m. Wind characteristics of the strong typhoon, such as mean wind speed and wind direction, turbulence intensity, turbulence integral length scale, gust factor and power spectra of wind velocity, vertical profiles of mean wind speed were investigated in detail based on the wind data recorded during the strong typhoon. The measured results revealed that the wind characteristics in different stages during the typhoon varied remarkably. Through comparison with non-typhoon wind measurements, the phenomena of enhanced levels of turbulence intensity, gust factors, turbulence integral length scale and spectral magnitudes in typhoon boundary layer were observed. The monitored data and analysis results are expected to be useful for the wind-resistant design of offshore structures and buildings on seashores in typhoon-prone regions.

• Journal of the Korean Solar Energy Society
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• v.23 no.2
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• pp.21-34
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• 2003

This study aims to present the applicability of wind turbine generator system to urban buildings for the utilization of clean renewable energy. The results are as follows; According to the wind resource analysis, it has been found that small sized wind power system can be viable for buildings application due to the amplification of wind velocity around buildings or building clusters, in spite of low mean velocity of 2-3m/s in Seoul and Kyunggi urban areas. But planners must perform micrositing analysis around building so that wind turbine can be located at high velocity zones. The system must be designed to avoid obstacles preventing prevailing wind in buildings. It should be recognized that wind speeds are changing depending on the height and length from buildings. The wind power system can be used as a symbol of landmark which shows a sustainable architecture from the scenary Itself A case study for apartment building in urban showed that wind power systems can be applicable in two kinds of place, rooftops and ground levels. Especially, the wind power systems must be carefully positioned so that wind resources do not decrease when it is installed at ground levels. and according to life cycle cost analysis, adaption of new small win4 power systems to buildings were proved to produce a profit if it is considered the expense of environment improvement and the wind speed increasing according to rise of building height. This research will ultimately achieve green architecture that preserves nature and at the same time provides pleasant environment to humans, and will play a great role in establishing the environment-preserving sustainable architecture of the 21th century.

• International Journal of High-Rise Buildings
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• v.1 no.2
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• pp.107-116
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• 2012

The overarching objective of this study is to predict the convective heat transfer around a human body under forced strong airflow conditions assuming a strong wind blowing through high-rise buildings or an air shower system in an enclosed space. In this study, computational fluid dynamics (CFD) analyses of the flow field and temperature distributions around a human body were carried out to estimate the convective heat transfer coefficient for a whole human body assuming adult male geometry under forced convective airflow conditions between 15 m/s and 25 m/s. A total of 45 CFD analyses were analyzed with boundary conditions that included differences in the air velocity, wind direction and turbulence intensity. In the case of approach air velocity $U_{in}=25m/s$ and turbulent intensity TI = 10%, average convective heat transfer coefficient was estimated at approximately $100W/m^2/K$ for the whole body, and strong dependence on air velocity and turbulence intensity was confirmed. Finally, the formula for the mean convective heat transfer coefficient as a function of approaching average velocity and turbulence intensity was approximated by using the concept of equivalent steady wind speed ($U_{eq}$).

• Wind and Structures
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• v.31 no.2
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• pp.165-183
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• 2020

The first step of performance-based design for transmission lines is the determination of wind fields as well as wind loads, which are largely depending on local wind climate and the surrounding terrain. Wind fields in a mountainous area are very different with that in a flat terrain. This paper firstly investigated both mean and fluctuating wind characteristics of a typical mountainous wind field by wind tunnel tests and computational fluid dynamics (CFD). The speedup effects of mean wind and specific turbulence properties, i.e., turbulence intensity, power spectral density (PSD) and coherence function, are highlighted. Then a hybrid simulation framework for generating three dimensional (3D) wind velocity field in the mountainous area was proposed by combining the CFD and proper orthogonal decomposition (POD) method given the properties of the target turbulence field. Finally, a practical 220 kV transmission line was employed to demonstrate the effectiveness of the proposed wind field generation framework and its role in the performance-based design. It was found that the terrain-induce turbulence effects dominate the performance-based structural design of transmission lines running through the mountainous area.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.5
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• pp.260-268
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• 2017

In this study, wind characteristics of a shipping container were investigated through the wind tunnel test (high-frequency force balance test), and damage occurrence velocities of various containers with weights were evaluated based on results of the wind tunnel tests. As a result, mean wind force coefficients acting on containers in x-direction increased in the order of 12ft, 20ft, 40ft and 40ft high cube. On the other hand, mean wind force coefficients at y-direction increased in the order of 40ft high cube, 40ft, 20ft and 12ft. It was suggested that the shear layer separated from the corner of windward surface of the container is reattached on the sides of it, and then the mean wind force coefficient is weaker. As a result of the damage occurrence velocity on containers with weights, it was found that the probability of occurrence of sliding is higher rather than that of overturning. Further, the most unfavorable container was 40ft high cube, and the sliding and overturning occurrence velocities were 20.4 m/s and 26.8 m/s, respectively. Furthermore, the regression formula for sliding and overturing occurrence velocitys were proposed based on the results of relationship between weights of containers and damage occurrence velocities. These results are expected to be useful in establishing a guideline for external force estimation acting on container securing equipment and stacking way.

• Journal of the Korean Data Analysis Society
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• v.20 no.6
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• pp.2941-2951
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• 2018

The purpose of this paper is to analyse the effect of ocean weather factors on shipments of swimming crab. We use the data of data portal and ocean weather factors (mean wind velocity, mean atmospheric pressure, mean relative humidity, mean air temperature, mean water temperature, mean maximum wave height, mean significant wave height, maximum significant wave height, maximum wave height, mean wave period, maximum wave period). We did statistical analysis using Poisson regression analysis and negative binomial regression analysis. As the result of study, important factors influential in the shipments of swimming crab turn out to be mean wind velocity, mean atmospheric pressure, mean relative humidity, mean water temperature, maximum wave height, mean wave period and maximum wave period. the shipments of swimming crab increases as mean wind velocity, mean atmospheric pressure, mean relative humidity, mean water temperature increases or mean wave period increase. However, as maximum wave height, maximum wave period decreases, the shipment of swimming crab increases.

• Journal of the korean society of oceanography
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• v.38 no.3
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• pp.135-142
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• 2003

Gas flux across the air-sea interface is often determined by the product of gas transfer velocity k) and the difference of concentrations in water and air. k is primarily controlled by wind stress on the air-sea interface, thus all parameterizations ofk involve wind speed, a rough indicator of wind stress, as one of the independent variables. We attempted to explore the spatial and temporal variations of k in the East (Japan) Sea using a database from Naet al. (1992). Three different parameterizations were employed: those of Liss and Merlivat (1986), Wanninkhof(1992), and Wanninkhofand McGillis (1999). The strong non-linear dependence of k on wind speed in all parameterizations leads us to examine the effect of time resolution, in which the binned wind speeds are averaged, on the estimation ofk. Two time resolutions of 12 hours (short-term) and one month (long-term) were chosen. The mean wind speeds were fed into the given parameterizations, resulting in six different transfer velocities of $CO_2$ ranging from 12 to 32 cm/h. In addition to the threefold difference depending on the choice of parameterization, the long-term average of wind speed results in a value ofk up to 20% higher than the short-term (12 hours) average of wind speed due to the non-Rayleigh wind distribution in the East (Japan) Sea. While it is not known which parameterization is more reliable, this study proposes that the time-averaged wind speed should not be used in areas where non-Ralyleigh wind distribution prevails such as the East (Japan) Sea. The net annual $CO_2$ flux was estimated using the value of k described above and the monthly ${\Delta}fCO_2$ of Oh et al. (1999); this ranges from 0.034 to 0.11 Gt-C/yr.

• Smart Structures and Systems
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• v.17 no.6
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• pp.1067-1085
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• 2016

Nonstationary features existing in tropical storms have been frequently captured in recent field measurements, and the applicability of the stationary theory to the analysis of wind characteristics needs to be discussed. In this study, a tropical storm called Nakri measured at Taizhou Bridge site based on structural health monitoring (SHM) system in 2014 is analyzed to give a comparison of the stationary and nonstationary characteristics. The stationarity of the wind records in the view of mean and variance is first evaluated with the run test method. Then the wind data are respectively analyzed with the traditional stationary model and the wavelet-based nonstationary model. The obtained wind characteristics such as the mean wind velocity, turbulence intensity, turbulence integral scale and power spectral density (PSD) are compared accordingly. Also, the stationary and nonstationary PSDs are fitted to present the turbulence energy distribution in frequency domain, among which a modulating function is included in the nonstationary PSD to revise the non-monotonicity. The modulated nonstationary PSD can be utilized to unconditionally simulate the turbulence presented by the nonstationary wind model. The results of this study recommend a transition from stationarity to nonstationarity in the analysis of wind characteristics, and further in the accurate prediction of wind-induced vibrations for engineering structures.