• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2010년도 춘계학술대회 논문집
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• pp.541-542
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• 2010

• 한국입자에어로졸학회지
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• 제10권2호
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• pp.75-82
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• 2014

It is necessary to find out the reaction characteristics of $CaCO_3$ sorbent particles in air and $O_2/CO_2$ atmospheric conditions in order that an in-furnace desulfurization technique can be applied to oxy-fuel combustion system. In this study, rate of change of GMD(geometric mean diameter) and specific surface area of $CaCO_3$ sorbent particles reacted in DTF(drop tube furnace) experimental setup were analyzed to investigate the effect of particle size and humidity on the reaction characteristics of them. In air atmospheric condition, calcination process occurs actively within shorter residence times as the particle size increases. On the contrary, in $O_2/CO_2$ atmospheric condition, a calcination process is delayed as particle size increases. The increment of humidity accelerates calcination process in an air atmospheric condition and increase rate of calcination in an $O_2/CO_2$ atmospheric condition.

• 대기
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• 제16권3호
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• pp.169-185
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• 2006

We have investigated the wind speed variations over the leeward region when the strong wind blows. In this study we employ Envi-met numerical model to simulate the effect of surface boundary conditions. This model is applied for three cases which are characterized by land use and terrain height. The base case having natural geographical condition shows the weakest wind speed around lee side of Chunsudae. The others which remove the vegetation and cut off the terrain above 20 m ASL represent the stronger wind speed than base case. The main factor of this result is the surface friction. The distinct variation of wind is found at offshore area between Chunsudae and the southern part of village, but the northern part where is apart from Chunsudae shows a small variation of wind pattern. The weakening of wind speed around residential area is a maximum of 4~10 m/s when the wind blows in the village as strong as 55 m/s. The gust wind speed is weakened about 7~17 m/s in this case if the coefficient of gust wind adapted as 1.75.

• 한국대기환경학회지
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• 제12권4호
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• pp.369-376
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• 1996

Major atmospheric stability classification methods were evaluated with meteorological data obtained by scoustic sounding profiler (SODAR/RASS) in Seoul. The Psequill classificatio method, the method most widely used because of its good agreement in respect of synoptic scope under the steady state, fails to describe the time lag, the response time on stability by heating or cooling caused by daily insolation or noctrunal surface radiation. Horizontal and vertical standard deviation of wind fluctuation $(\sigma_A and \sigma_E)$ method tend to classify night-time stable condition (E, F class) into unstable condition (A, B class). The classification matrix tables for Vogt's vertical temperature difference and wind speed using method ($\Delta$T $\cdot$ U) and bulk Richardson number (Rb) were amended for practical use over Seoul. The modified tables for $\Delta$T $\cdot$ U and Rb method were made by using comprehensive frequency distribution from Pasquill's method and other existing results, and the correlation coefficient(r) was equal to 0.829. It was confirmed that atmospheric stability could be changed with monitoring site characteristics, height and vertical difference between sensors of monitoring station, and classification method itself.

• 한국대기환경학회지
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• 제8권2호
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• pp.138-145
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• 1992

Dependence of the standard deviation of wind direction fluctuations, ${\sigma}_{\theta}$, on atmospheric stability, averaging time and topography were analysed with the data measured at three sites, Youngjongdo beach of the Yellow Sea, Chuncheon basin and Doam-Dam valley. The results show that the mean value of ${\sigma}_{\theta}$ is large in complex terrain, the Doam-Dam site. It is notable that the large value of ${\sigma}_{\theta}$ at night is associated with the low wind speed and the strong stable condition. In order to study the long-period fluctuations of the wind direction, ${\sigma}_{\theta}$ for longer than 10 minutes averaging time was further analysed using the data obtained at the Chuncheon basin. At the averaging time shorter than 60 minutes, larger ${\sigma}_{\theta}$ is associated with longer averaging time in the strong stable condition. However, ${\sigma}_{\theta}$ was not affected significantly by wind speed and averaging time in neutral conditions. The results of the spectrum analysis for the time series data of wind direction showed that low-frequency fluctuations ranging from 10 to 60 minutes were dominated at the Chuncheon basin in strong stable condition.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1134-1139
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• 2004

Recently, development of flame control scheme has been hot issues in the combustion engineering. It has been held that flame shape can be controllable by pressure inside combustor. The influence of combustor atmospheric pressure on flame shape was investigated in the present study. The flame shape, flammable limit, flame temperature and nitric oxide emission were measured as functions of combustor atmospheric pressure and equivalence ratio. The reaction region became longer and wider with decreasing combustor atmospheric pressure by direct photography, hence reduction of blow off limit. This tendency was also observed in the mean flame temperature distribution. Nitric oxide emission decreased with decreasing combustor atmospheric pressure. Low NOx combustion is ascribed to wide-spread reaction region in the low atmospheric pressure condition. These results demonstrate that flame shape and nitric oxide emission can be controllable with combustor atmospheric pressure.

• 대기
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• 제19권2호
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• pp.155-168
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• 2009

Characteristics of seasonal mean diurnal temperature range (DTR) and their causes over South Korea are investigated using the 60 stations data of Korea Meteorological Administration from 1976 to 2005. In general, the seasonal mean DTR is greatest during spring (in inland area) and least during summer (urban and coastal area). The spatial and seasonal variations of DTR are closely linked with the land surface conditions (especially vegetation activity and soil moisture) and atmospheric conditions (cloud amount, precipitation, local circulation). The seasonal mean DTR shows a decreasing trend at the major urban areas and at the north-eastern part of South Korea. Whereas, it shows an increasing trend at the central area of the southern part. Decreasing and increasing trends of DTR are more significant during summer and fall, and during spring and winter. The decrease (increase) of DTR is mainly caused by the stronger increase of daily minimum (maximum) temperature than daily maximum (minimum) temperature. The negative effects of precipitation and cloud amount on the DTR are greater during spring and at the inland area than during winter and at the coastal area. And the effect of daytime precipitation on the DTR is greater than that of nighttime precipitation.

• 접착 및 계면
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• 제4권4호
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• pp.1-6
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• 2003

대기압 플라즈마를 이용하여 폴리프로필렌 필름의 표면을 처리한 후 각각 극성 용매(water)와 비극성 용매(diiodomethane)를 사용한 접촉각 측정기로 필름 표면의 접촉각을 측정하였다. 측정된 접촉각을 이용해 표면 자유에너지 변화를 계산한 후 대기압 플라즈마 처리 전후의 폴리프로필렌 필름의 접촉각과 표면 자유에너지 상태를 비교, 분석하였다. 또한 대기압 플라즈마의 처리 조건을 바꿔가며 폴리프로필렌 필름 표면을 처리함으로써 접촉각과 표면 자유에너지가 각각의 처리 조건에 따라 어떠한 영향을 받는지 연구하였다. 대기압 플라즈마 처리 조건에 따라 접촉각 및 표면 자유에너지는 최적값을 보여주거나 일정한 값에 도달하는 경향을 보여 주었다.

• 한국환경과학회지
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• 제24권6호
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• pp.807-817
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• 2015

In this study the urban atmospheric environment map in Busan was made and it consist of the atmospheric environment element map and the atmospheric environment analysis map. The atmospheric environment element map covered the topography, the urban climate, the air pollutant emission, ozone and PM10 concentrations in Busan and the atmospheric environment analysis map included the thermal environment and the wind flow by using WRF meteorological numerical simulation. The meteorological elements from 2007 to 2011 in Busan were used in this study. As a result, in the center of Busan and Buk-gu along to the Nakdong river was the temperature high. To analyze the air flow of Busan 3 clusters depending on the wind direction were extracted with the cluster analysis. The results of the analysis on the detailed wind field of each cluster showed that the weak ventilation could be happened locally at the specific meteorological condition.

• 대한원격탐사학회지
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• 제23권1호
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• pp.7-14
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• 2007

Atmospheric correction is one of critical procedures to extract quantitative information related to biophysical variables from hyperspectral imagery. Most atmospheric correction algorithms developed for hyperspectral data have been based upon atmospheric radiative transfer (RT) codes, such as MODTRAN. Because of the difficulty in acquisition of atmospheric data at the time of image capture, the complexity of RT model, and large volume of hyperspectral data, atmospheric correction can be very difficult and time-consuming processing. In this study, we attempted to develop an efficient method for the atmospheric correction of EO-1 Hyperion data. This method uses the pre-calculated look-up-table (LUT) for fast and simple processing. The pre-calculated LUT was generated by successive running of MODTRAN model with several input parameters related to solar and sensor geometry, radiometric specification of sensor, and atmospheric condition. Atmospheric water vapour contents image was generated directly from a few absorption bands of Hyperion data themselves and used one of input parameters. This new atmospheric correction method was tested on the Hyperion data acquired on June 3, 2001 over Seoul area. Reflectance spectra of several known targets corresponded with the typical pattern of spectral reflectance on the atmospherically corrected Hyperion image, although further improvement to reduce sensor noise is necessary.