• The Korean Journal of Ecology
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• 제11권4호
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• pp.193-200
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• 1988

The amount of Pinus rigida pollen deposition was hourly measured by Durhan's pollen trap in Seoul National University during May 9∼16 o'clock and 9∼15, 1988. The peak times or pollen deposition were 9∼10 o'clock and 16∼17 o'clock. The correlation coefficients between pollen deposition and mean temperature, relative humidity, and wind speed were 0.625, -0.655 and 0.418 respectively, It is thought that pollen maturation rate is correlated with mean temperature and the pollen deposition with increasing wind speed.

• 한국환경생태학회지
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• 제34권5호
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• pp.425-435
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• 2020

본 연구는 도심지 산지형 공원의 물리적 구조 및 식생구조가 기상에 미치는 영향을 분석하기 위해 물리적 구조인 표고, 경사도, 사면 향, 지형구조와 식생 구조인 현존식생, 흉고직경, 울폐도의 기상과의 평균비교를 실시하였다. 분석 결과, 표고의 경우 상대습도, 풍속, 일사에서 유형 간 차이가 있는 것으로 분석되었으며, 경사도의 경우 풍속을 제외한 모든 기상요소에서 유형 간 차이가 있는 것으로 분석되었다. 사면 향의 경우 기온과 상대습도에서 유형간 차이나 있는 것으로 분석되었다. 지형구조의 경우 계곡부, 사면부, 능선부로 구분하였으며, 상대습도에서 측정 값의 차이가 있는 것으로 분석되었으나 기온, 풍속, 일사량에서는 일정한 경향과 유형간 차이가 미미한 것으로 분석되었다. 식생구조 중 현존식생의 경우 일사량을 제외한 기온, 상대습도, 풍속 항목에서 유형 간 차이가 있는 것으로 분석되었으며, 흉고직경의 경우 기온, 풍속, 일사량 항목에서 유형 간 유의한 차이가 있는 것으로 분석되었다. 울폐도의 경우 기온과 일사량에서 유의한 차이가 있는 것으로 분석되었다. 식생 및 물리적구조가 기상환경에 미치는 영향 분석을 위한 관계분석결과 기온의 경우 경사도와 사면 향, 흉고직경과 울폐도에서 영향을 받는 것으로 분석되었으며, 상대습도의 경우 물리적구조인 표고, 경사도, 사면 향, 지형구조와 식생구조인 현존식생과 울폐도에서 상관성이 분석되었다. 풍속의 경우 표고, 현존식생, 흉고직경에서 상관성이 분석되었으며, 일사량의 경우 경사도와 흉고직경, 울폐도간의 상관성이 분석되었다. 전반적으로 기온과 상대습도, 일사량에 가장 큰 영향을 주는 인자는 울폐도로 분석되었으며, 다음으로 경사도에서 상관관계가 높게 분석되는 경향이 나타났다. 흉고직경 또한 기온과 일사량간의 상관성이 매우 높은 것으로 분석되었으며 풍속과의 상관관계도 나타났으나 상대습도는 통계적인 유의성이 나타나지 않았다.

• 한국소음진동공학회논문집
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• 제19권8호
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• pp.809-815
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• 2009

The previous work(Cheong et al., 2006) where the characteristics of acoustic emissions of wind turbines has been investigated according to the methods of power regulation, has showed that the acoustic power of wind turbine using the stall control for power regulation is more correlated with the wind speed than that using the pitch control. In this paper, basically extending this work, the noise generation characteristics of large modern upwind wind turbines are experimentally indentified according to the power regulation methods. To investigate the noise generation mechanisms, the distribution of noise sources in the rotor plane is measured by using the beam-forming measurement system(B&K 7768, 7752, WA0890) consisting of 48 microphones. The array results for the 660 kW wind turbine show that all noise is produced during the downward movement of the blades. This result show good agreement with the theoretical result using the empirical formula with the parameters: the convective amplification; trailing edge noise directivity; flow-speed dependence. This agreement implies that the trailing edge noise is dominant over the whole frequency range of the noise from the 660 kW wind turbine using the pitch control for power regulation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.63-67
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• 2009

The previous work (Cheong et al., 2006) where the characteristics of acoustic emissions of wind turbines has been investigated according to the methods of power regulation, has showed that the acoustic power of wind turbine using the stall control for power regulation is more correlated with the wind speed than that using the pitch control. In this paper, basically extending this work, the noise generation characteristics of large modern upwind wind turbines are experimentally indentified according to the power regulation methods. To investigate the noise generation mechanisms, the distribution of noise sources in the rotor plane is measured by using the Beam-forming measurement system (B&K 7768, 7752, WA0890) consisting of 48 microphones. The array results for the 660 kW wind turbine show that all noise is produced during the downward movement of the blades. This result show good agreement with the theoretical result using the empirical formula with the parameters: the convective amplification; trailing edge noise directivity; flow-speed dependence. This agreement implies that the trailing edge noise is dominant over the whole frequency range of the noise from the 660 kW wind turbine using the pitch control for power regulation.

• Spatial Information Research
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• 제21권4호
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• pp.1-6
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• 2013

본 연구는 2002년부터 2009년까지 국내에서 발생한 돌풍에 대한 시계열 및 공간분포를 분석하였다. 태풍 기간 동안에 발생한 돌풍에 대해서는 제외하였으며, 지형에 의한 풍속 할증 효과는 KBC 2005 기준을 적용하여 보정하였다. 분석 결과, 돌풍 발생 빈도는 해안지역을 따라 높은 빈도가 나타났으며, 대상 기간 중 최대 286회의 발생 빈도를 보였다. 본 연구에서는 뇌우에 의한 돌풍과 종관 기상에 의해 발생한 돌풍의 시계열 분포의 비교를 통해 뇌우에 의한 돌풍의 불확실성이 높음을 확인하였다. 또한 누적운량과 뇌우 돌풍의 공간적 상관분석을 통해 두 인자간 높은 상관관계가 있음을 근거로 하여 돌풍에 대한 공간적 위험도를 평가하는데 활용할 수 있음을 제시하였다.

• Asian Journal of Atmospheric Environment
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• 제5권2호
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• pp.105-112
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• 2011

In order to investigate the effects of local and synoptic meteorological conditions on urban scale particulate air pollutants observed over the Busan coastal area, power spectrum analysis was applied to observed particulate matter with an aerodynamic diameter $\leq10\;{\mu}m$ ($PM_{10}$) for the period from 1 October, 1993 to 31 December, 2004. Fast Fourier Transform (FFT) analysis was used to obtain the hourly mean observed $PM_{10}$ concentrations to identify different periodicity scales of $PM_{10}$ concentrations. The results showed that, aside from the typical and well-known periodicities such as diurnal and annual variations caused by anthropogenic influences, three other significant power spectral density peaks were identified: 7-day, 21-day and 2.25-year periodicities. Cospectrum analysis indicated that the seven-day variations were closely related to the synoptic meteorological conditions such as weak wind speed, which are relevant to the stagnant high pressure system slowly passing through the Korean Peninsula. The intra-seasonal 21-day variation was negatively correlated with wind speed but was consistently positively correlated with relative humidity, which is related to aerosol formation that can be achieved as a result of the hygroscopic characteristics of aerosols. However, the quasibiennial 2.25-year variation was correlated with the frequency of Asian dust occurrence, the periodicities of which have been recorded inter-annually over the Korean Peninsula.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.1-9
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• 2007

Sensitivity analysis of wind resource micrositing has been performed through the application case at the Antarctic King Sejong station with the most representative micrositing softwares: WAsP, WindSim and Meteodyn WT. The wind data obtained from two met-masts separated 625m were applied as a climatology input condition of micro-scale wind mapping. A tower shading effect on the met-mast installed 20m apart from the warehouse has been assessed by the CFD software Fluent and confirmed a negligible influence on wind speed measurement. Theoretically, micro-scale wind maps generated by the two met-data located within the same wind system and strongly correlated meteor-statistically should be identical if nothing influenced on wind prediction but orography. They, however, show discrepancies due to nonlinear effects induced by surrounding complex terrain. From the comparison of sensitivity analysis, Meteodyn WT employing 1-equation turbulence model showed 68% higher RMSE error of wind speed prediction than that of WindSim using the ${\kappa}-{\epsilon}$ turbulence model, while a linear-theoretical model WAsP showed 21% higher error. Consequently, the CFD model WindSim would predict wind field over complex terrain more reliable and less sensitive to climatology input data than other micrositing models. The auto-validation method proposed in this paper and the evaluation result of the micrositing softwares would be anticipated a good reference of wind resource assessments in complex terrain.

• Journal of Ecology and Environment
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• 제36권1호
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• pp.65-71
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• 2013

The concentration of airborne pollen is related to meteorological parameters. The main purpose of this study was to determine the correlation between airborne pollen and meteorological parameters in Ulsan based on sampling from 2010 to 2011. The primary factors of interest were differences in the pollen scattering start date, end date, and peak date, and the fluctuations in pollen concentration. The meteorological parameters that affected the start and peak dates of the pollen season were as follows. For Pinus and Alnus, the dates were correlated with sunshine and an increase in temperature, whereas for Quercus, the dates were correlated with increasing temperature. During the pollen season, Alnus peaked when the temperature was highest and Pinus peaked when the relative humidity was lowest. The concentration of airborne pollen was correlated with meteorological parameters during the sampling period as follows: Pinus, Alnus, and Humulus pollen concentrations were positively correlated with increasing temperature and negatively correlated with rainfall and relative humidity; Humulus pollen concentration was positively correlated with sunshine; and Quercus and Humulus pollen concentrations were positively correlated with wind speed.

• Journal of Astronomy and Space Sciences
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• 제34권2호
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• pp.105-110
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• 2017

Solar wind density depletions are phenomena that solar wind density is rapidly decreased and keep the state. They are generally believed to be caused by the interplanetary (IP) shocks. However, there are other cases that are hardly associated with IP shocks. We set up a hypothesis for this phenomenon and analyze this study. We have collected the solar wind parameters such as density, speed and interplanetary magnetic field (IMF) data related to the solar wind density depletion events during the period from 1996 to 2013 that are obtained with the advanced composition explorer (ACE) and the Wind satellite. We also calculate two pressures (magnetic, dynamic) and analyze the relation with density depletion. As a result, we found total 53 events and the most these phenomena's sources caused by IP shock are interplanetary coronal mass ejection (ICME). We also found that solar wind density depletions are scarcely related with IP shock's parameters. The solar wind density is correlated with solar wind dynamic pressure within density depletion. However, the solar wind density has an little anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. Additionally, In 47 events of IP shocks, we find 6 events that show a feature of blast wave. The quantities of IP shocks are weaker than blast wave from the Sun, they are declined in a short time after increasing rapidly. We thus argue that IMF strength or dynamic pressure are an important factor in understanding the nature of solar wind density depletion. Since IMF strength and solar wind speed varies with solar cycle, we will also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an additional clue to their physical nature.

• 산업기술연구
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• 제25권B호
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• pp.89-97
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• 2005

Application of proper orthogonal decomposition (POD) and continuous wavelet transform (CWT) is introduced to study wind speed and building roof pressures of flow separation region. In this study, a detailed analysis of the approach wind flow, wind-induced building pressure and the relation between the two fields was carried out using the POD technique and CWT analysis. The results show potential of the application of POD and CWT in characterization of spatio-temporal and spectral properties of the approach wind and its induced dynamic pressure events. Some of findings resulting from the application of this analysis can be summarized as follows: (1) The POD first principal coordinate of the roof pressure in the separated shear layer is closely correlated with the longitudinal component of oncoming flow. (2) The CWT analysis suggests that the extreme peak pressure in the separated shear layer is due to condensed large-scale eddy motions.