• Wind and Structures
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• 제23권3호
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• pp.191-209
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• 2016

Wind tunnel tests of a 1/2200-scale mountainous terrain model have been carried out to investigate local wind characteristics at a bridge location in southeast Tibet, China. Flows at five key locations on the bridge at deck level were measured for 26 directions. It was observed that wind characteristics (including mean wind velocity and overall turbulence intensity) vary significantly depending on the approaching wind direction and measurement position. The wind inclination angle measured in the study fluctuated between $-18^{\circ}$ and $+16^{\circ}$ and the ratio of mean wind velocity to reference wind velocity was small when the wind inclination angles were large, especially for positive wind inclination angles. The design standard wind speed and the minimum critical wind speed for flutter rely on the wind inclination angle and should be determined from the results of such tests. The variation of wind speed with wind inclination angles should be of the asymmetry step type. The turbulence characteristics of the wind were found to be similar to real atmospheric flows.

• 물과 미래
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• 제21권4호
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• pp.389-397
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• 1988

남해 연안 지상측정소의 과거풍속자료와 돌풍 기록으로 부터 과거의 피해 자료를 추산(Hindcasting)하고 이로부터 얻어진 지역별 피해별 연간 최대피해의 극치 계열로 부터 확율분석을 통하여 송해 설계치를 결정하는 방법이 제안되엇다. 남해 연안에 내재하는 큰 파급은 돌풍과 춘하절 계절풍에 의해 생성되며 지역별 파향별로 상당한 차이를 보인다. 재현기간이 100년인 설계 유의파의 파고는 송해에서 4.6m~ 8.8m ,조기는 8.2sec~ 12.9sec의 범위를 보인다. 남해\ulcorner\ulcorner에서 풍속 $U_1$ >15m/s의 강풍에 대하여 일반적으로 해상풍속(Uw)은 \ulcorner\ulcorner 지상관측소 풍속($U_1$)의 0.8~0.9배 정도를 나타낸다. 남해 \ulcorner\ulcorner의 지상관측소에서 지속기간의 평균풍속($U_1$)은 2$U_{10}$)의 0.7~0.9배의 값을 가지면서 역지수 함수적으로 감소한다.

• Wind and Structures
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• 제27권4호
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• pp.223-234
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• 2018

In this study, a simplified three-dimensional calculation model is developed for the dynamic analysis of soil-pile group-supertall building systems excited by wind loads using the substructure method. Wind loads acting on a 300-m building in different wind directions and terrain conditions are obtained from synchronous pressure measurements conducted in a wind tunnel. The effects of soil-structure interaction (SSI) on the first natural frequency, wind-induced static displacement, root mean square (RMS) of displacement, and RMS of acceleration at the top of supertall buildings are analyzed. The findings demonstrate that with decreasing soil shear wave velocity, the first natural frequency decreases and the static displacement, RMS of displacement and RMS of acceleration increase. In addition, as soil material damping decreases, the RMS of displacement and the RMS of acceleration increase.

• Wind and Structures
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• 제10권1호
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• pp.23-44
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• 2007

Wind tunnel experiments on small scale groups of tanks are reported in the paper, with the aim of evaluating the pressure patterns due to group effects. A real tank configuration is studied in detail because one tank buckled during a hurricane category 3. Three configurations are studied in a wind tunnel, two with several tanks and different wind directions, and a third one with just one blocking tank. The pressures were measured in the cylindrical part and in the roof of the tank, in order to obtain pressure coefficients. Next, computational buckling analyses were carried out for the three configurations to evaluate the buckling pressure of the target structure. Finally, imperfection-sensitivity was investigated for one of the configurations, and moderate sensitivity was found, with reductions in the maximum load of the order of 25%. The results help to explain the buckling of the tank for the levels of wind experienced during the hurricane.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.142-145
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• 2006

The synergism of active and passive microwave techniques for hurricane ocean wind remote sensing is explored. We performed the analysis of Windsat data for Atlantic hurricanes in 2003-2005. The polarimetric third Stokes parameter observations from the Windsat 10, 18 and 37 GHz channels were collocated with the ocean surface winds from the Holland wind model, the NOAA HWind wind vectors and the Global Data Assimilation System (GDAS) operated by the National Center for Environmental Prediction (NCEP). The collocated data were binned as a function of wind speed and wind direction, and were expanded by sinusoidal series of the relative azimuth angles between wind and observation directions. The coefficients of the sinusoidal series, corrected for atmospheric attenuation, have been used to develop an empirical geophysical model function (GMF). The Windsat GMF for extreme high wind compares very well with the aircraft radiometer and radar measurements.

• 한국생산제조학회지
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• 제21권5호
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• pp.747-754
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• 2012

A solar power generator is usually installed outdoors and it is exposed to extreme environments such as snow weight and wind loading. The solar tracker structure should be designed to have sufficient stiffness and strength against such loads. In this paper, simulations are performed by varying the parameters such as wind directions, wind speeds and the pose of the solar panel to evaluate the effects of extreme wind on solar tracker. As the effects of wind load, maximum displacement and maximum equivalent stress in the solar tracker are calculated. Finite element stress analysis is carried out by using the pressure distribution that is obtained by prior wind load analysis due to the flow around the solar tracker. The stress analysis of solar tracker to check and/or improve structural robustness provides some useful instructions for structural design or revision of solar tracker.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.596-600
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• 2009

We are developing a simple low-cost wind velocity sensor based on small microphones. The sensor system consists of 4 microphones covered with specially shaped wind screens, 4 pre-amplifiers that respond to low frequency, and a commercial sound interface with multi channel inputs. In this paper, we first present the principle of the sensor, i.e., technique to successfully suppress the influence of external noise existing in the environment in order to determine the wind velocity and the wind direction from the output from a microphone. Then, we present an application for generating realistic motions of a virtual tree swaying in real wind. Although the current sensor outputs significant leaps in a measured sequence of directions, the interactive animations demonstrate that it is usable for such applications, if we could reduce the leaps to some degree.

• Wind and Structures
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• 제24권6호
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• pp.657-677
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• 2017

This paper discusses some features and conditions that characterize the Zonda wind, focusing particularly on the implications for wind engineering applications. This kind of wind, typical of mountainous regions, is far from being adequately characterized for computational simulations and proper modeling in experimental facilities such as boundary layer wind tunnels. The objective of this article is to report the research works that are being developed on this kind of wind, describing the main obtained results, and also to establish some general guidelines for the proper analysis of the Zonda in the wind engineering context. A classification for the Zonda wind is indicated and different cases of structural and environmental effects are described. Available meteorological data is analyzed from the wind engineering point of view to obtain the Zonda wind gust factors, as well as basic wind speeds relevant for structural design. Some considerations and possible directions for the Zonda wind-tunnel and computational modeling are provided. Gust factor values larger than those used for open terrain were obtained, nevertheless, the basic wind speed values obtained are similar to values presented by the Argentinian Wind Code for three-second gust, principally at Mendoza airport.

• 환경영향평가
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• 제16권2호
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• pp.157-168
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• 2007

In case there is a need to run the multi-year urban scale air qulaity model, it is a difficult task due to the computational demand, requiring the statistical approach for the long time atmospheric environmental assessment. In an effort to approach toward long term urban assessment, the sixteen synoptic meteorological conditions are statistically classified from the estimated geostrophic wind speeds and directions of 850 hPa geopotential height field during 2000 ~ 2005. The geostrophic wind directions are subdivided into four even intervals (north, east, south, and west), geostrophic wind speeds into two classes(${\leq}5m/s$ and >5m/s), and daily mean cloud amount into 2 classes(${\leq}5/10$ and >5/10), which result into sixteen classes of the synoptic meteorological cases for each season. The frequency distributions for each 16 synoptic meteorological case are examined and some discussions on how these synoptic classifications can be used in the environmental assessment are presented.

• Wind and Structures
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• 제8권3호
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• pp.197-212
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• 2005

Tall buildings under wind action usually oscillate simultaneously in the along-wind and across-wind directions as well as in torsional modes. While several procedures have been developed for predicting wind-induced loads and responses in along-wind direction, accurate analytical methods for estimating across-wind and torsional response have not been possible yet. Simplified empirical formulas for estimation of the across-wind dynamic responses of rectangular tall buildings are presented in this paper. Unlike established empirical formulas in codifications, the formulas proposed in this paper are developed based on simultaneous pressure measurements from a series of tall building models with various side and aspect ratios in a boundary layer wind tunnel. Comparisons of the across-wind responses determined by the proposed formulas and the results obtained from the wind tunnel tests as well as those estimated by two well-known wind loading codes are made to examine the applicability and accuracy of the proposed simplified formulas. It is shown through the comparisons that the proposed simplified formulas can be served as an alternative and useful tool for the design and analysis of wind effects on rectangular tall buildings.