• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.277-283
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• 2003

This paper constructed the 3D real-time numerical model for which predicts the water quality and movement characteristics of the inner bay, which consider the characteristics of the wind-driven current and density current in estuaries which generated by the river discharge from the Hyeong-san river and oceanic water of the Eastern sea. The constructed numerical model reappeared successfully the seawater circulation current of Yeong-il Bay, which used the input conditions of the real-time tidal current, river discharge and weather conditions at March of 2001 year. Also to observe the wind-driven current and density current in estuaries effected to the seawater circulation pattern of the inner bay, we investigated the analyzation for the each impact factors and the relationship with the water quality of Yeong-il bay

• Wind and Structures
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• v.5 no.2_3_4
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• pp.209-226
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• 2002

When predicting unsteady flow and pressure fields around a structure in a turbulent boundary layer by Large Eddy Simulation (LES), velocity fluctuations of turbulence (inflow turbulence), which reproduce statistical characteristics of the turbulent boundary layer, must be given at the inflow boundary. However, research has just started on development of a method for generating inflow turbulence that satisfies the prescribed turbulence statistics, and many issues still remain to be resolved. In our previous study, we proposed a method for generating inflow turbulence and confirmed its applicability by LES of an isotropic turbulence. In this study, the generation method was applied to a turbulent boundary layer developed over a flat plate, and the reproducibility of turbulence statistics predicted by LES computation was examined. Statistical characteristics of a turbulent boundary layer developed over a flat plate were investigated by a wind tunnel test for modeling the cross-spectral density matrix for use as targets of inflow turbulence generation for LES computation. Furthermore, we investigated how the degree of correspondence of the cross-spectral density matrix of the generated inflow turbulence with the target cross-spectral density matrix estimated by the wind tunnel test influenced the LES results for the turbulent boundary layer. The results of this study confirmed that the reproduction of cross-spectra of the normal components of the inflow turbulence generation is very important in reproducing power spectra, spatial correlation and turbulence statistics of wind velocity in LES.

• Journal of Hydrogen and New Energy
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• v.24 no.6
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• pp.558-565
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• 2013

This paper presents how to determine AEP(Annual Energy Production) by a small wind turbine in DuckjeokDo island. Evaluation of AEP is introduced to make a self-contained island including renewable energy sources of wind, solar, and tidal energy. To determine the AEP in DuckjeokDo island, a local wind data is analyzed using the annual wind data from Korea Institute of Energy Research firstly. After the wind data is separated in 12-direction, a mean wind speed at each direction is determined. And then, a small wind turbine power curve is selected by introducing the capacity of a small wind turbine and the energy production of the wind turbine according to each wind direction. Finally, total annual wind energy production for each small wind turbine can be evaluated using the local wind density and local energy production considering a mechanical energy loss. Throughout the analytic study, it is found that the AEP of DuckjeokDo island is about 2.02MWh/y and 3.47MWh/y per a 1kW small wind turbine installed at the altitude of 10 m and 21m, respectively.

• Smart Structures and Systems
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• v.21 no.5
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• pp.591-600
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• 2018

The probabilistic characterization of wind field characteristics is a significant task for fatigue reliability assessment of long-span railway bridges in wind-prone regions. In consideration of the effect of wind direction, the stochastic properties of wind field should be represented by a bivariate statistical model of wind speed and direction. This paper presents the construction of the bivariate model of wind speed and direction at the site of a railway arch bridge by use of the long-term structural health monitoring (SHM) data. The wind characteristics are derived by analyzing the real-time wind monitoring data, such as the mean wind speed and direction, turbulence intensity, turbulence integral scale, and power spectral density. A sequential quadratic programming (SQP) algorithm-based finite mixture modeling method is proposed to formulate the joint distribution model of wind speed and direction. For the probability density function (PDF) of wind speed, a double-parameter Weibull distribution function is utilized, and a von Mises distribution function is applied to represent the PDF of wind direction. The SQP algorithm with multi-start points is used to estimate the parameters in the bivariate model, namely Weibull-von Mises mixture model. One-year wind monitoring data are selected to validate the effectiveness of the proposed modeling method. The optimal model is jointly evaluated by the Bayesian information criterion (BIC) and coefficient of determination, $R^2$. The obtained results indicate that the proposed SQP algorithm-based finite mixture modeling method can effectively establish the bivariate model of wind speed and direction. The established bivariate model of wind speed and direction will facilitate the wind-induced fatigue reliability assessment of long-span bridges.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.271-277
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• 1998

1. Why Wind Power\ulcorner Advantages of Wind Energy : free cost, non-pollutant, free waste large unit is possible Disadvantages : intermittent of energy density limited sites Unit Capacity of various Power Plant Solar PP : 10 - 500㎾ Wind PP : 200 - 2000 ㎾ Nuclear PP 700 - 1000 MW Installation Cost of Power Plants Nuclear PP : $ 2,500/㎾ Solar PP : $ 6,000/㎾ Wind PP : $ 1.000 /kw.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.164-176
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• 2003

During summer, the DIN (dissolved inorganic nitrogen) and DIP (dissolved inorganic phosphate) observed in the Jindong Bay in the southern sea of Korea show much higher values in the inner area of the bay. In general, they have high values in the upper (0-1 m) and lower layers (8 m-bottom), but are relatively lower in the middle layer (1-8 m). These features in their distribution are examined using an ecosystem model with considering the wind, tidal current, horizontal gradient of water density and residual flow. The experiments were focused on how to influence nutrients associated with these conditions. In the experiment with tide-induced residual flow, the values of nutrients appeared lower than the observation, and were well corresponded to it when the effects of wind, tide-induced residual current and horizontal gradient of water density were additionally imposed. A statistical analysis identifies these results. This paper suggests that variation of nutrient in the Jindong Bay during summer should be seriously a(footed wind-driven current by the wind and density-driven current is induced by the horizontal gradient of water density as well as tidal current.

• Wind and Structures
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• v.30 no.1
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• pp.1-13
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• 2020

The loss prediction and assessment during extreme events such as wind hazards is always crucial for the group low-rise residential buildings. This paper analyses the effect of variation in building density on wind-induced loss for low-rise buildings and proposes a loss assessment method consequently. It is based on the damage matrices of the building envelope structures and the main load-bearing structure, which includes the influence factors such as structure type, preservation degree, building density, and interaction between different envelope components. Accordingly, based on field investigation and engineering experience, this study establishes a relevant building direct economic loss assessment model. Finally, the authors develop the Typhoon Disaster Management System to apply this loss assessment methodology to practice.

• Atmosphere
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• v.25 no.4
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• pp.685-692
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• 2015

In this study, the effects of trees on flow and scalar dispersion in an urban street canyon were investigated using a computational fluid dynamics (CFD) model. For this, we implemented the drag terms of trees to the CFD model, and compared the CFD-simulated results to the wind-tunnel results. For comparison, we considered the same building configuration as the wind-tunnel experiment. The trees were located at the center of street canyon with the aspect ratio (defined as the ratio of the street width to the building height) of 1. First, the flow characteristics were analyzed in the tree-free and high-density tree cases and the results showed that the CFD model reproduced well the flow pattern of the wind-tunnel experiment and reflected the drag effect of trees in the street canyon. Then, the dispersion characteristics of scalar pollutants were investigated for the tree-free, low-density tree and medium-density tree cases. In the tree-free case, the nondimensionalized concentration distribution simulated by the CFD model was quite similar to that in the wind-tunnel experiment in magnitude and pattern. The correlation coefficients between the measured and simulated concentrations are more than 0.9 in all the cases. As the tree density increased, nondimensionalized concentration increased (decreased) near the wall of the upwind (downwind) building, which resulted from the decrease in wind speed case by the drag effect of trees. However, the CFD model underestimated (overestimated) the concentration near the wall of upwind (downwind) building.

• Wind and Structures
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• v.36 no.2
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• pp.121-131
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• 2023

Aiming at the problem that fatigue characteristics of metal roof rely on local physical tests and lacks the cyclic load sequence matching with regional climate, this paper proposed a method of constructing the fatigue load spectrum based on integration of wind load model, measured data of long-span metal roof and climate statistical data. According to the turbulence characteristics of wind, the wind load model is established from the aspects of turbulence intensity, power spectral density and wind pressure coefficient. Considering the influence of roof configuration on wind pressure distribution, the parameters are modified through fusing the measured data with least squares method to approximate the actual wind pressure load of the roof system. Furthermore, with regards to the wind climate characteristics of building location, Weibull model is adopted to analyze the regional meteorological data to obtain the probability density distribution of wind velocity used for calculating wind load, so as to establish the cyclic wind load sequence with the attributes of regional climate and building configuration. Finally, taking a workshop's metal roof as an example, the wind load spectrum is constructed according to this method, and the fatigue simulation and residual life prediction are implemented based on the experimental data. The forecasting result is lightly higher than the design standards, consistent with general principles of its conservative safety design scale, which shows that the presented method is validated for the fatigue characteristics study and health assessment of metal roof.

• New & Renewable Energy
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• v.7 no.2
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• pp.36-42
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• 2011

The wind speed at the altitude around 300 m is much higher and less variable than at the altitude around 80 m which is the same height of the MW class tower turbine's hub height. The wind power density is increased 0.37 W/$m^2$ per meter at the altitude around 6 to 7 km and 0.25 W/$m^2$ per meter at the altitude around 80 to 500 m. There are two types of power generation systems using lifting bodies. The one is that The generator is installed in the ground station and stretched into the lifting body through the tether. The other is that the generator is installed in the lifting body and stretched into the ground station through the tether. Many kinds of lifting bodies are also researched in the world, called kites, wings, single or twin aerostat, and so on. This article introduced the technical development status and the market prospects of the high altitude wind power generation system all over the world in detail.