• Wind and Structures
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• 제37권2호
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• pp.163-178
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• 2023

The paper reviews and discusses the substantive changes to the ASCE 49-21 Standard, Wind Tunnel Testing for Buildings and Other Structures. The most significant changes are the requirements for wind field simulations that utilize (i) partial turbulence simulations, (ii) partial model simulations for the flow around building Appurtenances, along with requirements for determining wind loads on products that are used at multiple sites in various configurations. These modifications tend to have the effect of easing the precise scaling requirements for flow simulations because it is not generally possible to construct accurate models for small elements placed, for example, on large buildings at the scales typically available in boundary layer wind tunnels. Additional discussion is provided on changes to the Standard with respect to measurement accuracy and data acquisition parameters, such as duration of tests, which are also related to scaling requirements. Finally, research needs with respect to aerodynamic mechanisms are proposed, with the goal of improving the understanding of the role of turbulence on separated-reattaching flows on building surfaces in order to continue to improve the wind tunnel method for determining design wind loads.

• 대한원격탐사학회지
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• 제23권3호
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• pp.211-219
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• 2007

Building extraction is one of the essential issues for 3D city modelling. In recent years, high-resolution satellite imagery has become widely available and it brings new methodology for urban mapping. In this paper, we have developed a semi-automatic algorithm to determine building heights from monoscopic high-resolution satellite data. The algorithm is based on the analysis of the projected shadow and actual shadow of a building. Once two roof comer points are measured manually, the algorithm detects (rectangular) roof boundary automatically. Then it estimates a building height automatically by projecting building shadow onto the image for a given building height, counting overlapping pixels between the projected shadow and actual shadow, and finding the height that maximizes the number of overlapping pixels. Once the height and roof boundary are available, the footprint and a 3D wireframe model of a building can be determined. The proposed algorithm is tested with IKONOS images over Deajeon city and the result is compared with the building height determined by stereo analysis. The accuracy of building height extraction is examined using standard error of estimate.

• 대한건축학회논문집:구조계
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• 제34권11호
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• pp.27-35
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• 2018

The purpose of this study is to examine the effects of boundary RC frame(composed of one tie-beam and two tie-columns) on seismic performance of unreinforced masonry walls to suggest alternative way for seismic design of unreinforced masonry wall structures. Two test specimens are prepared, one is a typical unreinforced masonry wall and another is alternative unreinforced masonry wall with additional boundary RC frame. The structural experiments were carried out to evaluate the difference of seismic resistance performance between two test specimens with or without the boundary RC frames. From the test results, it was found that the failure mode of unreinforced masonry wall fundamentally changed from 'brittle' to 'ductile' by the installing of boundary RC frames. And, the maximum load and energy dissipation capacity of the test specimen with boundary RC frame was increased about 1.6~1.7 and 2~3 times respectively compared with a typical unreinforced masonry wall specimen.

• 한국환경과학회지
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• 제21권2호
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• pp.203-215
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• 2012

In order to clarify the impacts of thermal difference in atmospheric boundary layer due to the different sophistication of building information in Busan metropolitan areas, several numerical simulations were carried out. ACM (Albedo Calculation Model) and WRF (Weather Research and Forecasting) was applied for estimating albedo and meteorological elements in urban area, respectively. In comparison with coarse aggregated and small buildings, diurnal variation of albedo is highly frequent and its total value tend to be smaller in densely aggregated and tall buildings. Estimated TKE and sensible heat flux with sophisticatedly urban building parameterization is more resonable and valid values are mainly induced by urban building sophistication. The simulation results suggest that decreased albedo and increased roughness due to skyscraper plays an important role in the result of thermal change in atmospheric boundary layer.

• Wind and Structures
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• 제20권4호
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• pp.579-607
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• 2015

A Combination Random Flow Generation (CRFG) technique for obtaining the fluctuating inflow boundary conditions for Large Eddy Simulation (LES) is proposed. The CRFG technique was developed by combining the typical RFG technique with a novel calculation of k and ${\varepsilon}$ to estimate the length- and time-scales (l, ${\tau}$) of the target fluctuating turbulence field used as the inflow boundary conditions. Through comparatively analyzing the CRFG technique and other existing numerical/experimental results, the CRFG technique was verified for the generation of turbulent wind velocity fields with prescribed turbulent statistics. Using the turbulent velocity fluctuations generated by the CRFG technique, a series of LESs were conducted to investigate the wind flow around S-, R-, L- and U-shaped building models. As the pressures of the models were also measured in wind tunnel tests, the validity of the LES, and the effectiveness of the inflow boundary generated by the CRFG techniques were evaluated through comparing the simulation results to the wind tunnel measurements. The comparison showed that the LES accurately and reliably simulates the wind-induced pressure distributions on the building surfaces, which indirectly validates the CRFG technique in generating realistic fluctuating wind velocities for use in the LES. In addition to the pressure distribution, the LES results were investigated in terms of wind velocity profiles around the building models to reveal the wind flow dynamics around bluff bodies. The LES results quantitatively showed the decay of the bluff body influence when the flow moves away from the building model.

• 한국측량학회지
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• 제30권3호
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• pp.305-312
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• 2012

본 논문은 항공라이다 데이터로부터 추출한 건물점으로부터 건물 경계를 재구성하는데 있어서 정확도와 연산 효율성을 향상시키는 것을 목적으로 한다. 이를 위하여 국지적 컨벡스헐 알고리즘을 3가지 측면에서 수정한 적응적 컨벡스헐 알고리즘을 제안하였다. 첫째, 연산 효율성을 향상시키기 위하여 점들의 밀도에 따라 경계 후보점을 먼저 추출한 후 경계점을 추출한다. 둘째, 폐색이나 오차가 포함된 건물에서 보다 안정적으로 건물 경계점을 추출하기 위하여 원시 데이터 구조를 바탕으로 탐색 반경을 적응적으로 변화시킨다. 셋째, 안마당과 오차에 의한 홀을 구분하기 위하여 점들 간의 거리와 ID를 이용한 내부 경계 초기점 탐지 기법을 적용한다. 제안 방법의 활용가능성을 평가하기 위하여 다양한 건물들을 포함하는 두 도시 지역에 적용한 결과, 모양상이성이 8.5%로써 기존의 대표적인 경계점 추출 방법에 비하여 우수하였으며 연산 효율성은 약 2배 향상된 것을 확인할 수 있었다.

• 대한공간정보학회지
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• 제17권1호
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• pp.43-52
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• 2009

라이다 자료는 건물에 대한 3차원 정보를 제공하고 있는 자료원으로서 도시계획을 위한 3차원 모형화와 건물의 가시권 분석과 같은 다양한 모형화에 이용되고 있다. 본 연구에서는 라이다 자료만을 이용하여 영상처리기법과 점자료처리기법에 기반하여 사용자의 개입을 최소화하면서 자동으로 건물을 추출할 수 있는 기법을 제안하였다. 입력된 라이다 자료를 이용하여 건물영역과 비건물영역을 분리하기 위하여 먼저 영상처리기법을 적용하였다. 또한 건물영역은 높이값에 대한 통계분석을 통해서 건물의 주옥상면과 남아있는 부분으로 구분하여 자료처리를 수행하였다. 아파트형, 계단형, 복합형 등의 다양한 유형의 건물이 존재하는 연구대상지역의 실험을 통해서 본 연구에서 제안한 자료처리기법을 적용하여 약 90%의 건물을 자동으로 추출할 수 있었다.

• Wind and Structures
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• 제12권6호
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• pp.553-574
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• 2009

This paper presents statistical analysis results of wind speed and atmospheric turbulence data measured from more than 30 anemometers installed at 15 different height levels on 325 m high Beijing Meteorological Tower and is primarily intended to provide useful information on boundary layer wind characteristics for wind-resistant design of tall buildings and high-rise structures. Profiles of mean wind speed are presented based on the field measurements and are compared with empirical models' predictions. Relevant parameters of atmospheric boundary layer at urban terrain are determined from the measured wind speed profiles. Furthermore, wind velocity data in longitudinal, lateral and vertical directions, which were recorded from an ultrasonic anemometer during windstorms, are analyzed and discussed. Atmospheric turbulence information such as turbulence intensity, gust factor, turbulence integral length scale and power spectral densities of the three-dimensional fluctuating wind velocity are presented and used to evaluate the adequacy of existing theoretical and empirical models. The objective of this study is to investigate the profiles of mean wind speed and atmospheric turbulence characteristics over a typical urban area.

• Wind and Structures
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• 제13권6호
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• pp.487-498
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• 2010

When designing structures to the wind action, the variation of the mean wind velocity and turbulence parameters with the height above the ground must be taken into account. This paper presents the numerical simulation results of atmospheric boundary layer (ABL) airflows, in a numerical domain with no obstacles and with a cubic building. The results of the flow characterization, obtained with the FLUENT CFD code were performed using the ${\kappa}-{\varepsilon}$ turbulence model with the MMK modification. The mean velocity and turbulence intensity profiles in the inflow boundary were defined in accordance with the Eurocode 1.4, for different conditions of aerodynamic roughness. The maintenance of the velocity and turbulence characteristics along the domain were evaluated in an empty domain for uniform incident flow and the ABL Eurocode velocity profiles. The pressure coefficients on a cubic building were calculated using these inflow conditions.

• 한국컴퓨터정보학회논문지
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• 제24권5호
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• pp.35-40
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• 2019

In this paper, we design and implement a partial denoising boundary matching system using indexing techniques. Converting boundary images to time-series makes it feasible to perform a fast search using indexes even on a very large image database. Thus, using this converting method we develop a client-server system based on the previous partial denoising research in the GUI(graphical user interface) environment. The client first converts a query image given by a user to a time-series and sends denoising parameters and the tolerance with this time-series to the server. The server identifies similar images from the index by evaluating a range query, which is constructed using inputs given from the client and sends the resulting images to the client. Experimental results show that our system provides many intuitive and accurate matching results.