• 한국대기환경학회지
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• 제23권6호
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• pp.640-652
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• 2007

The MM5, RAMS and WRF, meteorological models have provided the dynamical parameters as inputs to air quality model. A major content of this study is that significant characteristics of three models for high-ozone occurrence analyze for surface wind and air temperature fields and compare with observation data in Seoul metropolitan area. An analysis of air temperature field revealed that location of core in high temperature of MM5 and WRF differed from that of RAMS. MM5 and WRF indicated high temperature in Seoul but RAMS represented it on the outskirts of Seoul. MM5 and WRF were underestimated maximum temperature during daytime but RAMS simulated similar value with observation data. Surface wind field with three models, it was shown many differences at horizontal distribution of wind direction. RAMS indicated weak wind speed in land and strong sea breeze at coastal areas than MM5 and WRF. However wind speed simulated by three model were overestimated during both daytime and nighttime.

• 한국가시화정보학회지
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• 제11권1호
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• pp.28-33
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• 2013

This paper describes aerodynamic characteristics of an Archimedes spiral wind turbine with various angles of attack. The range of angles was controlled from $-30^{\circ}$ (clockwise) to $+30^{\circ}$ (clockwise). The rotating speed of wind turbine at the same angle of attack in both directions was different. The reason why the-maximum rotational speed was observed at $15^{\circ}$ in clockwise direction can be explained based on angular momentum conservation. Quantitative flow visualization around Archimedes wind turbine blade was carried out between $-15^{\circ}$ (clockwise) and $+15^{\circ}$ (counter clockwise) using high resolution PIV method. The relationship between drag force and rotating speeds was discussed. From these results, optimum design on yawing system of Archimedes spiral wind turbine may provide high efficiency on small wind power system.

• 한국강구조학회 논문집
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• 제19권2호
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• pp.223-231
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• 2007

풍속의 확률분포를 고려한 통영생산기지 LNG 하역설비인 Unloading arm의 신뢰성해석을 수행하였다. 기상대의 풍속 관측기록을 이용하여 풍속의 극치분포를 추정하였으며 구조물에 가해지는 풍하중은 풍속과 풍압계수를 적용한 분포하중으로 고려하였다. 하역설비는 판요소와 입체요소를 이용하여 모델링하였고 지면접촉부는 접촉요소를 이용하여 압축력에만 저항하도록 하였다. 신뢰성해석을 위해서 주요부위의 최대응력을 표현하는 응답면을 구하였으며 이 값이 허용응력 및 항복응력을 초과하는지의 여부를 신뢰함수로 정의하여 파괴확률을 구하였다. 또한, 재료강도의 저하가 파괴확률에 미치는 영향을 파악하기 위하여 민감도 분석을 수행하였다.

• 한국전기전자재료학회논문지
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• 제34권2호
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• pp.90-98
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• 2021

Piezoelectric ceramic fiber composite (PCFC) was fabricated using a planar electrode printed piezoelectric ceramic fiber driven in transverse mode for small-scale wind energy harvester applications. The PCFC consisted of an epoxy matrix material and piezoelectric ceramic fibers sandwiched by interdigitated electrode (IDE) patterned polyimide films. The PCFC showed an excellent mechanical performance under a continuous stress. For the fabrication of PCB cantilever harvester, five -PCFCs were vertically attached onto a flexible printed circuit board (PCB) substrate, and then PCFCs were serially connected through a printed Cu circuit. The energy harvesting performance was evaluated applying an inverted structure, which imples its free leading edge located at an open end but the trailing edge at a clamped end, to enhance strain energy in a wind tunnel. The output voltage of the PCB cantilever harvester was increased as the wind speed increased. The maximum output power was 17.2 ㎼ at a resistance load of 200 ㏀ and wind speed of 9 m/s. It is considered that the PCB cantilever energy harvester reveals a potential use for wind energy harvester applications.

• 한국항공우주학회지
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• 제44권5호
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• pp.399-406
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• 2016

대형 풍력터빈은 지상 전단 흐름 내에서 회전하면서 주기적인 유입속도의 변동 조건 하에 운용된다. 수직 전단흐름에 의해서 경계층 내의 유입 속도는 최고점에서 속도가 최대가 되고 최저점에서 속도가 최소가 된다. 이러한 공간적인 풍속 분포는 풍력터빈 로터의 허브와 저속회전축에서 6분력 하중에 대한 주기적인 진동을 야기한다. 본 연구에서는 수직 전단 흐름 효과를 무시한 균일 흐름장과 지상 전단 흐름효과를 고려한 두 가지 경우에 대한 공력 하중을 비교분석하였다. 계산 결과로부터 허브에서의 추력과 굽힘모멘트, LSS의 굽힘모멘트가 크게 변동하는 결과를 보여주었다. 따라서 지상 전단흐름 효과를 반영한 공력 해석이 피로 해석을 위해서 반드시 필요함을 확인하였다.

• 한국항해항만학회지
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• 제35권5호
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• pp.381-385
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• 2011

본 연구에서는 최대 발전량이 500kW인 서해 도서의 풍력-디젤 하이브리드 발전시스템에 대한 경제성 분석을 수행하였다. 이를 위해 해당 도서에 대한 연간 전력 부하 변동치와 바람 데이터를 수집하고 분석하였으며, 풍력을 포함하여 신재생 에너지에 대한 하이브리드 최적화 모델로 미국의 NREL에서 개발한 Homer 프로그램을 이용하였다. 풍력-디젤 하이브리드 발전시스템의 경제성을 판단하기 위해 풍속과 경유 가격을 변수로 하는 민감도 해석도 수행하였다. 그 결과, 현재의 조건에서는 경제성이 낮았으나, 풍속이 초속 3미터가 넘거나 경유 가격이 리터당 2.4달러를 초과할 경우 대상지역에도 풍력-디젤 하이브리드 발전시스템이 경제성을 갖는 것으로 평가되었다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.390-395
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• 2004

The characteristics of the circular arc shaped multi-blade windmil are investigatedl. The prototypical windmill was tested in the laboratory at wind tunnel speeds of 5.5, 9.4m/s. and the model windmill was also tested in the laboratory, The power and torque coefficients were studied as functions of the blade section, the aspect ratio for blade diameter and windmill radius(M = 0.3, 0.5, 0.7), the number of blades and finally the tip-speed ratio. The analysis of the experimental results for the model windmill showed that there is the highest revolutions per minute(R.P.M) at the circular arc shaped multi-blade windmill having the blade number 10, aspect ratio(M = 0.7). and the results for the prototypical windmill showed that the power coefficient increased to a maximum value and then decreased again with an increase in the tip speed ratio, while the torque coefficient decreased directly with an increase in the tip speed ratio Finally, the experimental results were compared with the Savonius blade. the maximum power coefficient for the arc shaped blade was greater than for the Savonius blade and occured at a lower tip speed ratio.

• 태양에너지
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• 제4권2호
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• pp.3-12
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• 1984

In this paper, how to design the wind power generation system is presented. It is shown that the wind system optimization can be achieved by consideration of the four factors; wind statistics, efficiency of conversion of wind energy to electrical energy, average annual energy extracted and load factor. The wind is characterized by a weibull probability function. The Weibull parameter is calculated for the characterizing wind and the primary design specification of ten different sites. Some graphs are presented, which can be used to design a wind system for maximum output of a specified load factor at given site. Two different systems, $V_c=0.4V_R$ and $V_c=0.5V_R$ are discussed, as samples, for investigation of the effects on the system through the variation of cut-in speed.

• 대기
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• 제17권4호
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• pp.349-364
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• 2007

The main purpose of this study is to examine the sensitivity of the WRF (Weather Research and Forecasting) in the wind field to the steepness of mountains in the case with a strong downslope wind occurred in the Yeongdong province. We conducted WRF simulations for February 13 2006. The initial and boundary data are from the NCEP/NCAR $1^{\circ}{\times}1^{\circ}$ GDAS. Arbitrary terrains of the mountains with a symmetric orography and an asymmetric one with steeper leeward slope, were introduced to examine the sensitivity of the shape of the mountains. The simulation with an asymmetric terrain results in stronger maximum surface wind by about $10ms^{-1}$ than with a symmetric terrain, especially in the narrow region from the peak to ~ 4 km away in the downstream. However, the maximum surface wind speed is weaker by $20ms^{-1}$ than with a symmetric terrain away from the narrow peak region. This indicates that the steeper slope leads to the intensification of downslope wind in the narrower region leeward. In addition, for the simulation with an asymmetric terrain, the strength of wave breaking is greater and the Lee wave is more dominant than for that with a symmetric terrain.

• Interaction and multiscale mechanics
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• 제3권4호
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• pp.309-320
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• 2010

With taking the geometric nonlinearity of bridge structure into account, a framework is presented for predicting the dynamic responses of a long-span suspension bridge subjected to running train and turbulent wind. The nonlinear dynamic equations of the coupled train-bridge-wind system are established, and solved with the Newmark numerical integration and direct interactive method. The corresponding linear and nonlinear processes for solving the system equation are described, and the corresponding computer codes are written. The proposed framework is then applied to a schemed long-span suspension bridge with the main span of 1120 m. The whole histories of the train passing through the bridge under turbulent wind are simulated, and the dynamic responses of the bridge are obtained. The results demonstrate that the geometric nonlinearity does not influence the variation tendency of the bridge displacement histories, but the maximum responses will be changed obviously; the lateral displacement of bridge are more sensitive to the wind than the vertical ones; compared with wind velocity, train speed affects the vertical maximum responses a little more clearly.