• Journal of Biosystems Engineering
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• 제14권4호
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• pp.272-281
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• 1989

It is desirable for the vertical wind tunnel which can build uniform air flow across the vertical duct to be used for the purpose of the investigation of the aerodynamic properties of grains. This study was conducted to examine how the air velocity profile in the vertical duct is influenced by the various alternations of the elements of the wind tunnel, and to prepare design guidance of the vertical wind tunnel which can be used for investigating aerodynamic properties of grains. In addition, several tests were conducted to locate the test section which can be applicable for determining the terminal velocity of grain. The following conclusions were obtained from the study: 1. The size and the location of the outlet of the plenum chamber should be determined such that the outlet air flow is less affected by the air flow and the back pressure by the side wall of the chamber. 2. The honeycomb was not helpful for attaining uniform air flow in case that the air flow profile at the bottom of the vertical duct is serverely different from the ideal one. 3. Even though considerable pressure drop was resulted from the screens installed within the vertical duct, the screens were helpful for attaining uniform air flow in the duct. 4. It is desirable for the test section to be located at the position that not only the air flow of the duct is not disturbed by the distorted back pressure in the plenum chamber, but also less boundary layer is developed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.818-821
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• 2005

The sound measurement procedures of IEC 61400-11 are applied to field test and evaluation of noise emission from 1.5 MW wind turbine generator (WTG) at Yongdang and 660 kW WTG at Hangwon in Jeju Island. Apparent sound power level, wind speed dependence and third-octave band levels are evaluated for both of WTGs. 1.5 MW WTG at Yongdang is found to emit lower sound power than 660 kW one at Hangwon, which seems to be due to lower rotating speed of the rotor of WTG at Yongdang. Equivalent continuous sound pressure levels (ECSPL) of 660 kW WTG at Hangwon vary more widely with wind speed than those of 1.5 MW WTG at Yongdang. The reason for this is believed to be the fixed blade rotating speed of WTG at Yongdang. One-third octave band analysis of the measured data show that the band components around 400-500 Hz are dominant for 1.5 MW WTG at Yongdang and those around 1K Hz are dominant for 660 kW WTG at Hangwon.

• Wind and Structures
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• 제16권1호
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• pp.1-23
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• 2013

The wind-induced transient response of internal pressure following the creation of a sudden dominant opening during the occurrence of high external pressure, in low-rise residential and industrial buildings was numerically investigated. The values of the ill-defined parameters namely the flow contraction coefficient, loss coefficient and the effective slug length were calibrated by matching the analytical response with the computational fluid dynamics predictions. The effect of a sudden i.e., "instantaneously created" windward opening in the Texas Technical University (TTU) test building envelope was studied for two different envelope flexibility-leakage combinations namely: (1) a quasi-statically flexible and non-porous envelope and (2) a quasi-statically flexible and porous envelope. The responses forced by creating the openings at different time leads/lags with respect to the occurrence of the peak external pressure showed that for cases where the openings are created in close temporal proximity to the peak pressure, the transient overshoot values of internal pressure could be higher than the peak values of internal pressure in the pre-sequent or subsequent resonant response. In addition, the influence of time taken for opening creation on the level of overshoot was also investigated for the TTU building for the two different envelope characteristics. Non-dimensional overshoot factors are presented for a variety of cavity volume-opening area combinations for (1) buildings with rigid/quasi-statically flexible non-porous envelope, and (2) buildings with rigid/quasi-statically flexible and porous envelope (representing most low rise residential and industrial buildings). While the factors appear slightly on the high side due to conservative assumptions made in the analysis, a careful consideration regarding the implication of the timing and magnitude of such overshoots during strong gusts, in relation to the steady state internal pressure response in cyclonic regions, is warranted.

• 한국항공우주학회지
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• 제37권3호
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• pp.240-247
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• 2009

전자광학추적장치의 공력특성연구를 위한 풍동시험을 수행하였다. 특히 실제 EOTS 작동중 관측부의 회전을 위한 작동기의 충분한 파워 측정을 위한 공력토크 특성을 조사하였다. EOTS의 관측창의 영향을 조사하기 위해 반구와 실린더로 이루어진 단순 모형 실험결과와의 비교를 수행하였다. 단순모형과 EOTS모형의 표면 압력을 비교한 결과를 통해 관측창의 위치에 따라 급격한 압력계수의 변화와 회전 관측부의 토크 특성에 많은 영향을 미치는 것을 발견하였다.

• Structural Engineering and Mechanics
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• 제76권2호
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• pp.269-278
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• 2020

In this paper, the mechanical characteristics of the open type hyperbolic-parabolic membrane structure under wind load were investigated. First, the numerical simulation of a typical plane membrane structure was performed based on the Large-Eddy Simulation method. The accuracy of the simulation method was validated by the corresponding wind tunnel test results. Then, the wind load shape coefficients of open type hyperbolic-parabolic membrane structures are obtained from the series of numerical calculations and compared with the recommended values in the "Technical Specification for Membrane Structures (CECS 158: 2015). Finally, the influences of the wind directions and wind speeds on the mean wind pressure distribution of open type hyperbolic-parabolic membrane structures were investigated. This study aims to gain a better understanding of the wind-induced response for this type of structure and be useful to engineers and researchers.

• 한국강구조학회 논문집
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• 제28권3호
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• pp.203-211
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• 2016

국내의 플랜트 탱크 설계를 위한 풍하중 기준은 KS B 6283 액체 저장 탱크의 내풍압 및 내진에 대한 설계 요건 등 여러기준에 제시되어 있으나, 그 내용이 서로 다르고 연관성도 없으며 실제의 풍하중을 반영하고 있는지 명확하지 않다. 국내 풍하중 기준의 정당성을 평가하고 적합한 풍하중 기준을 제안하기 위해 외국의 저장 탱크 설계를 위한 대표적 기준인 API 650, ASCE 7-10, EN 1991-1-4의 풍하중 기준 들과 비교분석하였다. 풍동 실험이 수행되어 보고된 논문에 적용된 탱크 제원을 적용하여 기본적으로 각 기준에 의한 압력계수 Cp값을 산정해 비교하고, 탱크 지붕 높이와 지름 비(f/d) 및 탱크 깊이 및 지름 비(h/d)를 변수로 한 각 기준에 의한 풍하중 좌굴해석을 수행하였다. 결과를 분석 종합하여 실제 풍하중에 의한 좌굴 거동을 반영하면서도 설계 시 쉽게 적용할 수 있는 풍하중 기준을 제안 하였다.

• 대기
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• 제24권3호
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• pp.445-456
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• 2014

A real-time quality control system for meteorological data (air temperature, air pressure, relative humidity, wind speed, wind direction, and precipitation) measured by an integrated meteorological sensor has been developed based on comparison of quality control procedures for meteorological data that were developed by the World Meteorological Organization and the Korea Meteorological Administration (KMA), using time series and statistical analysis of a 12-year meteorological data set observed from 2000 to 2011 at the Incheon site in Korea. The quality control system includes missing value, physical limit, step, internal consistency, persistence, and climate range tests. Flags indicating good, doubtful, erroneous, not checked, or missing values were added to the raw data after the quality control procedure. The climate range test was applied to the monthly data for air temperature and pressure, and its threshold values were modified from ${\pm}2{\sigma}$ and ${\pm}3{\sigma}$ to ${\pm}3{\sigma}$ and ${\pm}6{\sigma}$, respectively, in order to consider extreme phenomena such as heat waves and typhoons. In addition, the threshold values of the step test for air temperature, air pressure, relative humidity, and wind speed were modified to $0.7^{\circ}C$, 0.4 hPa, 5.9%, and $4.6m\;s^{-1}$, respectively, through standard deviation analysis of step difference according to their averaging period. The modified quality control system was applied to the meteorological data observed by the Weather Information Service Engine in March 2014 and exhibited improved performance compared to the KMA procedures.

• 한국항공우주학회지
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• 제33권7호
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• pp.1-8
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• 2005

풍동 시험부 비정상 벽면효과에 대한 연구를 위해 폐쇄형 시험부내의 원형 실린더 주위 유동장에 대한 수치적 연구를 수행하였다. 수치기법은 Roe의 flux-difference-splitting을 사용한 격자점 중심 유한체적법과 이중시간 전진 기법을 사용하는 내재적 시간적분법을 사용하였다. 계산 결과 폐쇄형 시험부에는 실린더 주위 비정상 유동장에 압력구배를 강화시켜 실린더의 양력 및 항력의 진폭을 크게 하고, 실린더 뒷전에서의 기저압력을 작게 하여 항력을 증가시키는 벽면효과가 있음을 확인하였다. 또한, 이러한 시험부 벽면은 실린더 와류 shedding 주파수를 커지게 하는 효과가 있다. 시험부 벽면에서의 압력은 벽면효과가 포함된 shedding 주파수를 기본으로 하는 고조파 현상을 보인다.

• 설비공학논문집
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• 제15권2호
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• pp.109-115
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• 2003

The performance of two vertical-blade eliminators (V1, V2) and two horizontal-blade ones (H1, H2) for absorption chillers were tested in terms of pressure drop and refrigerant entrainment. The test was carried out using a wind tunnel with a cross section of 300 mm$\times$300 mm. The pressure drop of four eliminators tested was found to be in the rage of 1.0~2.7mm $H_2O$ at the face velocity of 2m/s. In the refrigerant entrainment test the vertical-blade eliminators showed much better performance than the horizontal-blade ones. The horizontal-blade eliminators showed satisfactory results at the air velocity of 2m/s but exceeded the limit value at 3 m/s. Since the cooling capacity of a machine is lowered by about 2.5% at the pressure drop of 1 m $H_2O$, more researches are required to reduce the pressure drop in the eliminator.

• 한국항해항만학회지
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• 제32권3호
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• pp.251-255
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• 2008

컨테이너 크레인은 강풍으로부터 보호를 받기 위한 차폐물이 없는 곳에 존재하기 때문에 이상 기후 조건에 취약성이 있는 구조물이다. 본 연구에서는 풍향변화에 따라 컨테이너 크레인에 작용되는 풍하중을 분석하기 위하여 수행되었다. 사용된 모델은 61톤 급 컨테이너 크레인으로 현재 항만시설에 많이 사용되는 모델이다. 유동장은 원통으로 모델링하였으며, 직경 500m, 높이 200m로 설정하였다. 본 연구에서는 건축물 하중기준의 풍하중 설계기준에 따라 풍하중을 적용하였으며 풍향에 따른 영향을 분석하기 위해서 유동장을 $10^{\circ}$ 간격으로 분할하였다. 이를 바탕으로 CFX-10을 사용하여 전산유동해석을 수행하고 이를 통하여 얻어진 결과와 풍력실험 결과를 비교 연구함으로써, 컨테이너 크레인의 구조설계에 필요한 풍하중을 분석하였다.