• Wind and Structures
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• 제18권5호
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• pp.549-566
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• 2014

In spite of progress in the numerical simulation of typhoon wind field in atmospheric boundary layer (ABL), using typhoon wind field model in conjunction with Monte Carlo simulation method can only accurately evaluate typhoon wind field over a general terrain. This method is not enough for a reliable evaluation of typhoon wind field over the actual complex terrain with surface roughness and topography variations. To predict typhoon wind field over the actual complex terrain in ABL, a hybrid numerical simulation method combined typhoon simulation used the typhoon wind field model proposed by Meng et al. (1995) and CFD simulation in which the Reynolds averaged Navier-Stokes (RANS) equations and k-${\varepsilon}$ turbulence model are used. Typhoon wind filed during typhoon Dujuan and Imbudo are simulated using the hybrid numerical simulation method, and compared with the results predicted by the typhoon wind field model and the wind field measurement data collected by Fugro Geotechnical Services (FGS) in Hong Kong at the bridge site from the field monitoring system of wind turbulence parameters (FMS-WTP) to validate the feasibility and accuracy of the hybrid numerical simulation method. The comparison demonstrates that the hybrid numerical simulation method gives more accurate prediction to typhoon wind speed and direction, because the effect of topography is taken into account in the hybrid numerical simulation method.

• 대기
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• 제29권5호
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• pp.689-698
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• 2019

Air pollution in urban areas has become a serious problem in the recent years. Especially, high concentrations of particulate matter (PM) cause negative effects on human health. Several studies suggest urban forest as a tool for improving air quality because of the capability of forests in reducing PM concentrations through deposition and adsorption using leaf area. For this reason, the National Institute of Forest Science plans to install in-situ observation stations for PM and biogenic volatile organic compounds (BVOCs) on a national scale to verify the net effect of forests on urban air pollution. To measure the quantitative change of PM concentrations due to the urban forest, stations should be located within and outside the forest area with respect to atmospheric circulation. In this study, we analyze the wind direction at the potential measurement sites to assess suitable locations for detecting the effect of urban forests on air quality in five cities (i.e. Gwangju, Daegu, Busan, Incheon, and Ilsan). This technical note suggests effective locations of in-situ measurements by considering main wind direction in the five cities of this study. A measurement station network created in the future based on the selected locations will allow quantitative measurements of PM concentration and BVOCs emitted from the urban forest and help provide a comprehensive understanding of the forest capabilities of reducing air pollution.

• Wind and Structures
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• 제30권1호
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• pp.69-83
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• 2020

Modelling incompressible, neutrally stratified, barotropic, horizontally homogeneous and steady-state atmospheric boundary layer (ABL) is an important aspect in computational wind engineering (CWE) applications. The ABL flow can be viewed as a balance of the horizontal pressure gradient force, the Coriolis force and the turbulent stress divergence. While much research has focused on the increase of the wind velocity with height, the Ekman layer effects, entailing veering - the change of the wind velocity direction with height, are far less concerned in wind engineering. In this paper, a modified k-ε model is introduced for the ABL simulation considering wind veering. The self-sustainable method is discussed in detail including the precursor simulation, main simulation and near-ground physical quantities adjustment. Comparisons are presented among the simulation results, field measurement values and the wind profiles used in the conventional wind tunnel test. The studies show that the modified k-ε model simulation results are consistent with field measurement values. The self-sustainable method is effective to maintain the ABL physical quantities in an empty domain. The wind profiles used in the conventional wind tunnel test have deficiencies in the prediction of upper-level winds. The studies in this paper support future practical super high-rise buildings design in CWE.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.163-164
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• 2020

When measuring fine dust at a large-scale site such as complex construction, the change in the value of fine dust measurement is large due to the influence of the time, location, wind speed, wind direction, and humidity. This study aims to find out the results of measuring fine dust in an actual construction site and inferring the changes.

• 한국해안·해양공학회논문집
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• 제29권1호
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• pp.12-19
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• 2017

풍력 개발을 위한 해상기상탑은 초기 설치비와 유지보수비가 크기 때문에 윈드 라이다와 같은 원격관측장비를 이용하여 기상탑을 대체할 필요가 있다. 본 연구에서는 해상기상탑에서 윈드 라이다를 동시 운영하고 수집된 풍속 및 풍향의 관측결과를 상호 비교하여 윈드 라이다의 적용성을 검증하였다. 높이별 풍속 및 풍향 관측결과 두 자료간의 크기 및 경향 등의 통계적 특성 차이는 거의 없으며, 기상탑 관측자료는 구조물 차폐영향에 의한 오차가 발생하는 반면, 윈드 라이다는 오차가 없는 보다 정확한 자료를 얻을 수 있는 것을 확인하였다.

• Wind and Structures
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• 제19권4호
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• pp.353-370
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• 2014

A new method is proposed in this study for estimating the damping ratio of a super tall building under strong wind loads with short-time measured acceleration signals. This method incorporates two main steps. Firstly, the power spectral density of wind-induced acceleration response is obtained by the wavelet transform, then the dynamic characteristics including the natural frequency and damping ratio for the first vibration mode are estimated by a nonlinear regression analysis on the power spectral density. A numerical simulation illustrated that the damping ratios identified by the wavelet spectrum are superior in precision and stability to those values obtained from Welch's periodogram spectrum. To verify the efficiency of the proposed method, wind-induced acceleration responses of the Guangzhou West Tower (GZWT) measured in the field during Typhoon Usagi, which affected this building on September 22, 2013, were used. The damping ratios identified varied from 0.38% to 0.61% in direction 1 and from 0.22% to 0.59% in direction 2. This information is expected to be of considerable interest and practical use for engineers and researchers involved in the wind-resistant design of super-tall buildings.

• Wind and Structures
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• 제7권5호
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• pp.345-357
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• 2004

In the 1990s, four strong typhoons hit the Kyushu area of Japan and inflicted severe damage on power transmission facilities, houses, and so on. Maximum gust speeds exceeding 60 m/s were recorded in central Kyushu. Although the wind speeds were very high, the gust factors were over 2.0. No meteorological stations are located in mountainous areas, creating a deficiency of meteorological station data in the area where the towers were damaged. Since 1995 the authors have operated a network for wind measurement, NeWMeK, that measures wind speed and direction, covering these mountainous areas, segmenting the Kyushu area into high density arrays. Maximum gusts exceeding 70 m/s were measured at several NeWMeK sites when Typhoon Bart (1999) approached. The gust factors varied widely in southerly winds. The mean wind speeds increased due to effects of the local terrain, thus further increasing gust speeds.

• Wind and Structures
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• 제13권6호
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• pp.529-556
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• 2010

This paper investigates the correlation of wind characteristics monitored on a cable-stayed bridge. Total five anemoscopes are implemented into the bridge. Two out of 5 anemoscopes in inflow and two out of 5 anemoscopes in wake-flow along the longitudinal direction of the bridge are installed. Four anemoscopes are respectively distributed at two cross-sections. Another anemoscope is installed at the top of the tower. The correlation of mean wind speed and direction, power spectral density, the turbulent intensity and integral length of wind in flow at two cross-sections are investigated. In addition, considering the non-stationary characteristics of wind, the spatial correlation in time-frequency is analyzed using wavelet transform and different phenomenon from those obtained through FFT is observed. The time-frequency analysis further indicates that intermittence, coherence structures and self-similar structures are distinctly observed from fluctuant wind. The flow characteristics around the bridge deck at two positions are also investigated using the field measurement. The results indicate that the mean wind speed decrease when the flow passing through the deck, but the turbulence intensity become much larger and the turbulence integral lengths become much smaller compared with those of inflow. The relationship of RMS (root mean square) of wake-flow and the mean wind speed of inflow is approximately linear. The special structures of wake-flow in time-frequency domain are also analyzed using wavelet transform, which aids to reveal the forming process of wake-flow.

• 한국전자통신학회논문지
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• 제10권1호
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• pp.55-64
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• 2015

풍력시장은 매년 연 30%정도의 고도 성장률을 보이고 있으며, 점차 늘어나고 있는 추세이다. 국내 풍력발전기 설치 총량은 380MW로 전 세계시장의 0.2%의 점유율을 보이고 있다. 그러나 국내에 설치된 풍력발전기의 90%이상이 해외기업 제품이다. 또한 해상 풍력 발전소 설치를 위한 사전 조사 시스템에 적용되는 데이터로거도 대부분 해외기업 제품으로 막대한 비용이 해외로 유출되는 실정이다. 이에 본 논문에서는 풍력 발전기건설 업무의 효율성과 투자 비용절감을 위한 사전 기상자원 측정 시스템을 제안한다. 사전 기상자원 측정 시스템은 기상탑의 기상 관측 데이터로거 H/W와 무선 브리지, 기상탑 주변의 풍향, 풍속, 온 습도, 일사량, 데이터로거의 전력 상태를 모니터링할 수 있며, 측정된 데이터를 분석할 수 있는 Wind Rose S/W로 구성된 무선 통신(Wifi)기반의 해양 기상자원 측정 데이터로거 및 분석 모니터링 시스템이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.92-96
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• 2007

Microphone array beamforming method has been recognized as an important aeroacoustic research field and become a standard technique in localizing sound sources. This method also used in flight acoustic measurement, and especially, it is very useful when measure sounds inside the wind tunnel. In measuring sound which is inside the wind tunnel by traditional beamforming method, there are some errors caused by airstream. The speed and the propagation path of the sound changes as it travel through the airstream. This makes the error which the position of sound is changed a little bit to the down stream direction. In this paper, validation test has made about the correction equation for this wind effects of previous researches. And beamforming including shear layer correction was performed about a sound source in the anechoic open-jet windtunnel.