• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.382-383
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• 2018

To increase the efficiency of a wind energy conversion system (WECS), the maximum power point tracking (MPPT) algorithm is usually employed. This paper proposes an optimal MPPT algorithm which tracks a sudden wind speed change condition fast. The proposed method can be implemented without the prior information on the wind turbine parameters, generator parameters, air density or wind speed. By investigating the directions of changes of the mechanical output power in wind turbine and rotor speed of the generator, the proposed MPPT algorithm is able to determine an optimal speed to achieve the maximum power point. Then, this optimal speed is set to the reference of the speed control loop. As a result, the proposed MPPT algorithm forces the system to operate at the maximum power point by using a three-phase converter. The simulation results based on the PSIM are given to prove the effectiveness of the proposed method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.123-129
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• 2006

The measurement method of natural wind to understand the characteristics of the natural wind along the railway lines in Korea has been investigated to be used in the assessment of the risk of train overturn. The weather information service provided by Korea Meteorological Administration has been employed to outline the broad characteristic of natural wind in Korea. Anemometers using CDMA telecommunication for data transfer have been installed near the railway lines to measure velocities and directions of natural wind and the data processing method has been studied using the measured data.

• 대한원격탐사학회지
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• 제31권2호
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• pp.65-75
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• 2015

본 연구에서는 전산유체역학 모델과 지리정보시스템 자료를 이용하여 밀양시 내이동에 위치한 자동지상관측소(AWS 288)의 지상 바람 관측환경을 분석하였다. AWS 288 인근 지역에 건축 중인 아파트 단지에 의한 관측환경 변화를 분석하기 위하여 16방위의 유입류를 고려하였다. AWS 위치에서 수치 모의된 풍속과 풍향 변화를 중점적으로 분석하였고, 3가지 유입류(남남서풍, 남남동풍, 북북서풍)에 대해서는 AWS 288 주위의 흐름 특성을 상세하게 분석하였다. 남남서풍의 경우, AWS 288 지점에서는 남서쪽에 위치한 아파트 단지의 영향으로 아파트 단지 건축 전과 후의 풍속 차이가 가장 크게 나타났다. 아파트 단지 건축 전에 상대적으로 높은 풍향 빈도가 나타난 남남동풍과 북북서풍의 경우에는 아파트 단지 건축 전 대비 건축 후의 AWS 288 지점에서 수치 모의된 풍속과 풍향 차이는 크지 않았다.

• Wind and Structures
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• 제31권5호
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• pp.431-443
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• 2020

The modern tall buildings are often constructed as an unconventional plan and as twin buildings. Wind load on the tall building is significantly influenced by the presence of another building in the near vicinity. So, it is imperative to study wind forces on an unconventional plan shaped tall building. Mean wind pressure coefficients of a square and 'H' plan shape tall buildings are investigated using wind tunnel experiments. The experiments were carried out for various wind directions from 00 to 900 at an interval of 300 and various locations of the identical interfering building. The experimental results are presented at the windward face from the viewpoint of effects on cladding design. To quantify the interference effects, interference factors (I.F) are calculated. Mean pressure coefficients of both models are compared for isolated and interference conditions. The results show that pressure reduces with an increase in wind angle till 600 wind direction. The interfering building at full blockage interference condition generates more suction than the other two conditions. The interference factor for both models is less than unity. H-plan building model is subjected to a higher pressure than the square model.

• Wind and Structures
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• 제1권1호
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• pp.43-57
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• 1998

A three-degree-of-freedom base hinged assembly (BHA) for aeroelastic model tests of tall building was developed. The integral parts of a BHA, which consists of two perpendicular plane frames and a flexural pivot, enable this modeling technique to independently simulate building translational and torsional degree-of-freedom. A program of wind tunnel aeroelastic model tests of the CAARC standard tall building was conducted with emphasis on the effect of (a) torsional motion, (b) cross-wind/torsional frequency ratio and (c) the presence of an eccentricity between center of mass and center of stiffness on wind-induced response characteristics. The experimental results highlight the significant effect of coupled translational-torsional motion and the effect of eccentricity between center of mass and center of stiffness on the resultant rms acceleration responses in both along-wind and cross-wind directions especially at operating reduced wind velocities close to a critical value of 10. In addition, it was sound that the vortex shedding process remains the main excitation mechanism in cross-wind direction even in case of tall buildings with coupled translational-torsional motion and with eccentricity.

• 대한원격탐사학회지
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• 제25권1호
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• pp.1-10
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• 2009

각종 위성자료와 현장 관측자료를 이용하여 2004년 겨울철 황해 연안해역 이상수온 상승 현상과 외해의 해양 변동과의 연관성에 대하여 연구하였다. 위성자료에 의하면, 2003년 황해의 평균 해수면온도는 $10^{\circ}C$ 정도였고, 2004년의 평균 해수면온도는 $13^{\circ}C$ 정도로 약 $3^{\circ}C$ 정도 높았다. 현장관측 자료에서는 2003년 황해의 평균 표층수온은 $9.85^{\circ}C$ 정도였고, 2004년의 평균 표층수온은 $12.17^{\circ}C$ 정도로 위성자료와 마찬가지로 약 $3^{\circ}C$ 정도 높았다. T-S diagram 분석에 의하면, 2003년은 황해 수괴와 동중국해 수괴를 아주 명확하게 구분되었지만, 2004년에는 양 수괴의 구분이 명확하지 않았다. 2003년의 평균 기온과 풍속은 각각 $5.23^{\circ}C$, 4.81 m/s 이고, 9004년의 평균 기온과 풍속은 각각 $5.61^{\circ}C$, 4.52 m/s 로 유사하였다. 그러나 2003년에는 북서풍이 우세하였으나, 2004년에는 다양한 북풍 계열의 바람이 불어서 풍향이 달랐다. 2004년 겨울철 황해 연안해역의 이상수온 상승은 대기의 영향보다 외해 해양 변동과 깊은 연관성이 있는 것으로 판단되었고, 이에 대해서는 추후 연구가 이루어질 것이다.

• 대한원격탐사학회지
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• 제37권6_2호
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• pp.1837-1847
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• 2021

본 연구는 지리정보시스템과 전산유체역학 모델을 이용하여 수원시 전역을 대상으로 바람길을 조사하였다. 최근 10년간 수원 종관기상관측소(ASOS 119)에서 측정한 평균 풍속을 이용하여 16방위의 유입 풍향에 대한 수치 모의를 수행하였다. 수원시는 산악 지형으로 둘러싸인 분지에 위치하고, 수원시 서부와 남부에는 장애물이 적은 농경지와 호수 평지가 넓게 분포하고 있다. 수원시 중부에는 낮은 산과 언덕이 곳곳에 산재하고 있고, 넓은 도로들과 하천이 길게 형성되어 있다. 서풍(주풍)과 동풍(평균 풍속이 강한 풍향) 경우를 상세하게 분석하고 16방위 풍향 빈도수를 가중치로 사용하여 평균한 풍속 분포 특성을 분석하였다. 수원시의 상세 바람특징을 다음과 같이 요약할 수 있다. (1) 수원 북부 지역은 높은 산악 지형에 의해 복잡한 흐름이 형성되었고, 풍상측(풍하측) 산사면에서 강한(약한) 바람과 상승(하강)기류가 모의되었다. (2) 풍하측 산사면에서는 골짜기를 따라 바람길이 형성되어 주거지역으로 비교적 강한 기류가 유입되었다. (3) 강풍 지역이 수원 서부와 남부의 장애물이 없는 넓은 지역에서 모의되었다. (4) 도심지에서는 건물에 의한 마찰과 흐름 차단으로 인해 풍속이 감소하고 복잡한 흐름장이 형성되었다. 도심지 주거 지역의 바람길은 넓은 도로와 하천, 호수, 저수지 등 장애물이 적은 지역을 따라 형성되었다.

• 한국태양에너지학회 논문집
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• 제32권2호
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• pp.87-94
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• 2012

In this study, we found a relationship between wind shear exponent, ${\alpha}$, and a few factors such as the wind speed, $V$, ruggedness index($RIX$), and the Weibull shape parameter, $k$ of sites in complex terrain in Korea. Wind shear exponents in main wind directions were calculated using wind speed data measured for one year from various heights of eleven meteorological masts in Gangwon province. It was found from the analysis that the reciprocal of the wind shear exponent can be expressed by an exponentially decaying function with respect to a multiple of $V$, $RIX$ and $k$. This result is considered useful to be used to characterize wind characteristics of specific sites in complex terrain in Korea with limited information.

• 대한조선학회논문집
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• 제52권3호
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• pp.255-264
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• 2015

Wind load and flow field of a drillship with respect to various super structures were experimentally investigated in KARI 1m-wide wind tunnel with an atmospheric boundary layer simulation. Six-component external balance and Particle image velocimetry technique were used to measure wind load and velocity vectors in the flow-field around the model respectively. The experimental model was an imaginary shaped drillship with an approximated model which has 1/640 scale compared with recent typical drillships. The test Reynolds number based on the overall length was about 1.5×10⁶. It was found that dominant factors influencing on ship wind load are cabin shape and cabin height. Round cabin has smaller axial wind load and narrow boundary layer around the ship than rectangular one, but its yawing moment at certain angles becomes higher. Low cabin height also show positive effects on axial wind load too. Hull shape and forecastle shape show relatively small influences on wind loads except for slight changes around ±45° wind directions.

• Wind and Structures
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• 제20권6호
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• pp.793-810
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• 2015

Tests were conducted at the Florida International University (FIU) Wall of Wind (WOW) to investigate the susceptibility of Variable Message Signs (VMS) to wind induced vibrations due to vortex shedding and galloping instability. Large scale VMS models were tested in turbulence representative of the high frequency end of the spectrum in a simulated suburban atmospheric boundary layer. Data was measured for the $0^{\circ}$ and $45^{\circ}$ horizontal wind approach directions and vertical attack angles ranging from $-4.5^{\circ}$ to $+4.5^{\circ}$. Analysis of the power spectrum of the fluctuating lift indicated that vertical vortex oscillations could be significant for VMS with a large depth ratio attached to a structure with a low natural frequency. Analysis of the galloping test data indicated that VMS with large depth ratios, greater than about 0.5, and low natural frequency could also be subject to galloping instability.