• Computational Structural Engineering : An International Journal
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• 제1권1호
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• pp.11-20
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• 2001

The paper describes the conceptual design, structural modelling and wind load analysis of tall buildings. The lateral stiffness of the building can be obtained economically through the interaction of core walls with peripheral frame tube and/or bundle of frame tubes and integrated design of the basement. The main structural components should be properly distributed such that the building will deflect mainly in the direction of the applied force without inducing significant response in other directions and twist. The cost effectiveness can be further enhanced through close consultation between architects and engineers at an early stage of conceptual design. Simplified structural modelling of the building and its response in three principal directions due to wind load are included. Effects of the two main structural components on the performances of a 70-story reinforced concrete building in terms of peak drift and maximum acceleration under wind load are discussed.

• 생물환경조절학회지
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• 제2권1호
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• pp.46-52
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• 1993

The wind pressure distributions were analyzed through the wind tunnel experiment to provide fundamental criteria for the structural design on the three-span arched house according to the wind directions. In order to investigate the wind force distribution, the variation of the wind force coefficients, the mean wind force coefficients, the drag force coefficients and the lift force coefficients were estimated from the experimental data. The results obtained are as follows : 1. The variation of the wind force with the wind directions on the side walls was the greatest at the upwind edge of the walls. The change of pressure from the positive to the negative on the side walls occurred at the wind direction of 30$^{\circ}$ in the first house and 60$^{\circ}$ in the third house. 2. The maximum negative wind force along the length of the roof appeared at the length ratio of 0-0.2, when the wind directions were 90$^{\circ}$ in the first house, 60$^{\circ}$ in the second house and 30$^{\circ}$ in the third house. 3. The maximum negative wind force along the width of the roof appeared at the width ratio and the wind direction of 0.4 and 0$^{\circ}$ in the first house, 0.4-0.6 and 30$^{\circ}$ in the second house and 0.6 and 30$^{\circ}$ in the third house, respectively. 4. The maximum mean positive and negative wind forces occurred at the wind direction of 60$^{\circ}$ and 30$^{\circ}$, respectively, on the side walls of the first house, and the maximum mean negative wind force on the roof occurred at the wind direction of 30$^{\circ}$ in third house. 5. The maximum drag and lift forces occurred at the wind direction of 30$^{\circ}$, and the maximum lift force appeared in the third house. 6. The parts to be considered for the local wind forces were the edges of the walls, the edges of the x-direction of the roofs, and the locations of the width ratio of 0.4 of the first and third house and the center of the width of the second house for the y-direction of the roofs.

• 생물환경조절학회지
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• 제1권2호
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• pp.142-147
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• 1992

The wind pressure distributions were analyzed to provide fundamental criteria for the structural design on the two-span arched house according to the wind directions through the wind tunnel experiment. In order to investigate the wind force distributions, the variation of the wind force coefficients, the mean wind force coefficients, the drag force coefficients and the lift force coefficients were estimated using the experimental data. The results obtained are as follows : 1. The variation of the wind force with wind directions on the side walls was the greatest at the upwind edge of the walls. 2. The maximum negative wind force along the length of the roof appeared at the upwind edge at the wind direction of 60$^{\circ}$. 3. The maximum negative wind force along the width of the roof appeared at the width ratio and wind direction of 0$^{\circ}$ and 0.4 in the first house and 0.6 and 30$^{\circ}$ in the second house, respectively. 4. The mean negative wind force on the side walls of the first house at the wind direction of 0$^{\circ}$ was far greater than that of the second house, and the maximum negative wind force on the roof occurred at the wind direction of 30$^{\circ}$. 5. The maximum lift force appeared on the second house at the wind direction of 30$^{\circ}$, but the lift force on the first house was far greater than that on the second house at the wind direction of 0$^{\circ}$. 6. The parts to be considered for the local wind forces were the edges of the walls, and the edges of the x-direction and the width ratio, 0.4 of the y-direction in the roofs.

• KIEAE Journal
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• 제4권3호
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• pp.103-107
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• 2004

This paper aims for evaluating the wind-driven ventilation in basement parking lots of apartment. Wind tunnel tests coupled with tracer gas method were conducted, and classified by wind directions and opening types. The test results showed that, as for wind-driven ventilations, stack type openings were more successful than scuttle vent. Finally, according to Weibull distribution in Seoul, yearly averaged wind-driven ventilation rate was calculated.

• 대기
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• 제27권1호
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• pp.67-77
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• 2017

In this study, we analyzed the characteristics of flow around the Daeyeon automatic weather station (AWS 942) and established formulas estimating inflow wind speeds at a computational fluid dynamics (CFD) model domain for the area around Pukyong national university using a computational fluid dynamics (CFD) model. Simulated wind directions at the AWS 942 were quite similar to those of inflows, but, simulated wind speeds at the AWS 942 decreased compared to inflow wind speeds except for the northerly case. The decrease in simulated wind speed at the AWS 942 resulted from the buildings around the AWS 942. In most cases, the AWS 942 was included within the wake region behind the buildings. Wind speeds at the inflow boundaries of the CFD model domain were estimated by comparing simulated wind speeds at the AWS 942 and inflow boundaries and systematically increasing inflow wind speeds from $1m\;s^{-1}$ to $17m\;s^{-1}$ with an increment of $2m\;s^{-1}$ at the reference height for 16 inflow directions. For each inflow direction, calculated wind speeds at the AWS 942 were fitted as the third order functions of the inflow wind speed by using the Marquardt-Levenberg least square method. Estimated inflow wind speeds by the established formulas were compared to wind speeds observed at 12 coastal AWSs near the AWS 942. The results showed that the estimated wind speeds fell within the inter quartile range of wind speeds observed at 12 coastal AWSs during the nighttime and were in close proximity to the upper whiskers during the daytime (12~15 h).

• 한국기계가공학회지
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• 제15권3호
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• pp.21-27
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• 2016

The static and dynamic structural integrity qualification was performed through the seismic analysis of a small-size Savonius-type vertical wind turbine at dead weight plus wind load and seismic loads. The ANSYS finite element program was used to develop the FEM model of the wind turbine and to accomplish static, modal, and dynamic frequency response analyses. The stress of the wind turbine structure for each wind load and dead weight was calculated and combined by taking the square root of the sum of the squares (SRSS) to obtain static stresses. Seismic response spectrum analysis was also carried out in the horizontal (X and Y) and vertical (Z) directions to determine the response stress distribution for the required response spectrum (RRS) at safe-shutdown earthquake with a 5% damping (SSE-5%) condition. The stress resulting from the seismic analysis in each of the three directions was combined with the SRSS to yield dynamic stresses. These static and dynamic stresses were summed by using the same SRSS. Finally, this total stress was compared with the allowable stress design, which was calculated based on the requirements of the KBC 2009, KS C IEC 61400-1, and KS C IEC 61400-2 codes.

• 대한기계학회논문집
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• 제12권4호
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• pp.892-899
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• 1988

본 연구에서는 특정한 콘테이너 크레인을 설계도면에 따라 100:1 축척의 모형 을 제작하고 Reynolds 수에 의한 축척영향, 모형취부 및 계측 시스템의 반복성 영향, 풍향에 따른 특성, boom의 위치에 따른 특성, 풍고도에 따른 특성, blockage 영향, 설 계변경에 따른 효과에 주 관심을 두고 연구하였다. 특히 설계단계에서 관련 규격에 따라 예측된 풍하중이 실제와 어느 정도로 일치하는지에 관심을 두고 풍동시험 결과와 비교했다.

• 대한원격탐사학회지
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• 제36권4호
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• pp.557-571
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• 2020

High-resolution flows around a steep mountainous island (Ulleungdo) in Korea were simulated by a computational fluid dynamics (CFD) model. To cover entire Ulleungdo and to resolve the topography around the Ulleungdo automatic synoptic observing system (ASOS) with high resolution, one-way nested grid system with large (60 m), and small (20 m) grid sizes was applied in the CFD model simulations. We conducted the numerical simulations for 16 inflow directions, and, for each inflow direction, we considered six different wind velocities(5, 10, 15, 20, 25, and 30 m s^-1) at the reference height (1,000 m). The effects of topography on surface wind observations were well reflected in the observed wind roses for the period of January 01, 2012 ~ December 31, 2016 at the Ulleungdo ASOS and marine buoy. Wind roses at the Ulleungdo ASOS was reproduced based on the CFD simulations. The changes in surface winds at the Ulleungdo ASOS caused by surrounding topography were relatively well simulated by the CFD model. The simulated wind-rose indicated that south-southwesterly and northeasterly were the dominant wind directions, which were also observed at the Ulleungdo ASOS. We investigated the flow characteristics around the Ulleungdo ASOS for northwesterly, south-southwesterly, and northeasterly winds in detail.

• Wind and Structures
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• 제26권6호
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• pp.369-382
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• 2018

Tornadoes are vertical swirling air formed because of the existence of layers of air with contrasting features of temperature, wind flow, moisture, and density. Tornadoes induce completely different wind forces than a straight-line (SL) wind. A suitably designed building for an SL wind may fail when exposed to a tornado-wind of the same wind speed. It is necessary to design buildings that are more resistant to tornadoes. In tornado-damaged areas, dome buildings seem to have less damage. As a dome structure is naturally wind resistant, domes have been used in back yards, as single family homes, as in-law quarters, man caves, game rooms, storm shelters, etc. However, little attention has been paid to the tornadic wind interactions with dome buildings. In this work, the tornado forces on a dome are computed using Computational Fluid Dynamics (CFD) for tornadic and SL wind. Then, the interaction of a tornado with a dome and a prism building are compared and analyzed. This work describes the results of the tornado wind effect on dome and prism buildings. The conclusions drawn from this study are illustrated in visualizations. The tornado force coefficients on a dome building are larger than SL wind forces, about 120% more in x- and y-directions and 280% more in z-direction. The tornado maximum pressure coefficients are also higher than SL wind by 150%. The tornado force coefficients on the prism are larger than the forces on the dome, about 100% more in x- and y-directions, and about 180% more in z-direction. The tornado maximum pressure coefficients on prism also are greater those on dome by 150% more. Hence, a dome building has less tornadic load than a prism because of its aerodynamic shape.

• Smart Structures and Systems
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• 제26권4호
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• pp.435-449
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• 2020

To effectively extract the vast wind resource, offshore wind turbines are designed with large rotor and slender tower, which makes them vulnerable to external vibration sources such as wind and wave loads. Substantial research efforts have been devoted to mitigate the unwanted vibrations of offshore wind turbines to ensure their serviceability and safety in the normal working condition. However, most previous studies investigated the vibration control of wind turbines in one direction only, i.e., either the out-of-plane or in-plane direction. In reality, wind turbines inevitably vibrate in both directions when they are subjected to the external excitations. The studies on both the in-plane and out-of-plane vibration control of wind turbines are, however, scarce. In the present study, the NREL 5 MW wind turbine is taken as an example, a detailed three-dimensional (3D) Finite Element (FE) model of the wind turbine is developed in ABAQUS. To simultaneously control the in-plane and out-of-plane vibrations induced by the combined wind and wave loads, another carefully designed (i.e., tuned) spring and dashpot are added to the perpendicular direction of each Tuned Mass Damper (TMD) system that is used to control the vibrations of the tower and blades in one particular direction. With this simple modification, a bi-directional TMD system is formed and the vibrations in both the out-of-plane and in-plane directions are simultaneously suppressed. To examine the control effectiveness, the responses of the wind turbine without control, with separate TMD system and the proposed bi-directional TMD system are calculated and compared. Numerical results show that the bi-directional TMD system can simultaneously control the out-of-plane and in-plane vibrations of the wind turbine without changing too much of the conventional design of the control system. The bi-directional control system therefore could be a cost-effective solution to mitigate the bi-directional vibrations of offshore wind turbines.