• 대기
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• 제18권4호
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• pp.287-297
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• 2008

The vertical profiles and optical properties of Asian dust are investigated using ground-based measurements from 1998 to 2002. Vertical profiles of aerosol extinction coefficient are evaluated using MPL (Micro Pulse Lidar) data. Optical parameters such as aerosol optical thickness ($\tau$), ${\AA}ngstr\ddot{o}m$ exponent ($\alpha$), single scattering albedo ($\omega$), refractive index, and volume size distribution are analyzed with sun/sky radiometer data for the same period. We can separate aerosol vertical profiles into three categories. First category named as 'Asian dust case', which aerosol extinction coefficient is larger than $0.15km^{-1}$ and dust layer exists from surface up to 3-4km. Second category named as 'Elevated aerosol case', which aerosol layer exists between 2 and 6km with 1-2.5km thickness, and extinction coefficient is smaller than $0.15km^{-1}$. Third category named as 'Clear sky case', which aerosol extinction coefficient appears smaller than $0.15km^{-1}$. and shows that diurnal variation of background aerosol in urban area. While optical parameters for first category indicate that $\tau$ and $\alpha$ are $0.63{\pm}0.14$, $0.48{\pm}0.19$, respectively. Also, aerosol volume concentration is increased for range of 1 and $4{\mu}m$, in coarse mode. Optical parameters for second category can be separated into two different types. Optical properties of first type are very close to Asian dust cases. Also, dust reports of source region and backward trajectory analyses assure that these type is much related with Asian dust event. However, optical properties of the other type are similar to those of urban aerosol. For clear sky case, $\tau$ is relatively smaller and $\alpha$ is larger compare with other cases. Each case shows distinct characteristics in aerosol optical parameters.

• 한국대기환경학회지
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• 제8권3호
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• pp.179-190
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• 1992

This study was carried out to characterize sources of atmospheric total suspended particulates (TSP) in urban and sub--urban areas of metropolitan taegu. The sources were tentatively identified by a multivariate technique, i.e. principal component analysis (PCA), and the source contributions to the atmospheric concentrations of TSP were further estimated by stepwise multiple regression analysis. A total of 5 sources was identified in the urban area of Taegu (soil dust resuspension, fuel combustion, secondary aerosol, traffic related aerosol, and refuge burning), while 4 sources were found to be significant in the sub--urban area as following: fuel combustion/secondary aerosol, soil dust resuspension, traffic related aerosol, and wood/agricultural burning. The largest contributor to the atmospheric TSP appeared to be the soil dust resuspension in both areas. The source apportionment of the extractable organic matter (EOM) was also carried out for the Taegu data. The EOM was determined with respect to the solvent polarity, i.e. cyclohexane (non-polar), dichloromethane (semi--polar), and acetone (polar). In addition, the source profiles for the TSP in Taegu area were estimated using a PCA-based algorithm, and the validity was evaluated tentatively by comparing the data in the literature.

• 대한원격탐사학회지
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• 제22권5호
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• pp.403-406
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• 2006

An algorithm for detection of yellow sand aerosols has been developed with infrared bands. This algorithm is a hybrid algorithm that has used two methods combined. The first method used the differential absorption in brightness temperature difference between $11{\mu}m\;and\;12{\mu}m\;(BTD1)$. The radiation at $11{\mu}m$ is absorbed more than at $12{\mu}m$ when yellow sand is loaded in the atmosphere, whereas it will be the other way around when cloud is present. The second method uses the brightness temperature difference between $3.7{\mu}m\;and\;11{\mu}m(BTD2)$. This technique is sensitive to dust loading, which the BTD2 is enhanced by reflection of $3.7{\mu}m$ solar radiation. First the Principle Component Analysis (PCA), a form of eigenvector statistical analysis from the two methods, is performed and the aerosol pixel with the lowest 10% of the eigenvalue is eliminated. Then the aerosol index (AI) from the combination of BTD 1 and 2 is derived. We applied this method to Multi-functional Transport Satellite-l Replacement (MTSAT-1R) data and obtained that the derived AI showed remarkably good agreements with Ozone Mapping Instrument (OMI) AI and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth.

• Asian Journal of Atmospheric Environment
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• 제6권4호
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• pp.304-313
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• 2012

In this study, the ${\AA}$ngstrom exponent for polydispersed aerosol during dynamic processes was investigated. Log-normal aerosol size distribution was assumed, and a sensitivity analysis of the ${\AA}$ngstrom exponent with regards the coagulation and condensation process was performed. The ${\AA}$ngstrom exponent is expected to decrease because of the particle growth due to coagulation and condensation. However, it is difficult to quantify the degree of change. In order to understand quantitatively the change in the ${\AA}$ngstrom exponent during coagulation and condensation, different real and imaginary parts of the refractive index were considered. The results show that the ${\AA}$ngstrom exponent is sensitive to changes in size distribution and refractive index. The total number concentration decreases and the geometric mean diameter of aerosols increase during coagulation. On the while, the geometric standard deviation approaches monodispersed size distribution during the condensation process, and this change in size distribution affects the ${\AA}$ngstrom exponent. The degree of change in the ${\AA}$ngstrom exponent depends on the refractive index and initial size distribution, and the size parameter changes with the ${\AA}$ngstrom exponent for a given refractive index or chemical composition; this indicates that the size distribution plays an important role in determining the ${\AA}$ngstrom exponent as well as the chemical composition. Subsequently, this study shows how the ${\AA}$ngstrom exponent changes quantitatively during the aerosol dynamics processes for a log-normal aerosol size distribution for different refractive indices; the results showed good agreement with the results for simple analytic size distribution solutions.

• 한국환경과학회지
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• 제22권8호
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• pp.1053-1062
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• 2013

The shortwave aerosol direct radiative forcing (SWARF) was analyzed using the Clouds and Earth's Radiant Energy System (CERES) data in the East Asian region from 2001 to 2010. In the Yellow Sea and the Korean Peninsula, located in the leeward side of China, significantly negative high SWARF at the top of atmosphere (TOA) occurs due to the long-range transport of anthropogenic (e.g. sulphate) and natural aerosols (e.g. mineral dust) from the East Asian continent. Conversely, eastern China has much higher levels of SWARF at the surface (SFC) due to anthropogenically emitted aerosol than in the Yellow Sea and the Korean Peninsula. Since the radiative forcing of aerosols in the atmosphere are different in type, aerosol types were classified into sea salt+sulphate, smoke, sulphate and dust by using satellite data. The analysis on the SWARF by the classified aerosol types indicated that sulphate occupies a predominant portion of the atmosphere in the Yellow Sea and the Korean Peninsula in the summer. In particular, the annual averages of the summer TOA SWARF increased in the Yellow Sea and the Korean Peninsula from 2001 to 2010.

• 한국지구과학회지
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• 제32권1호
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• pp.21-32
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• 2011

본 연구는 동아시아 영역에 속해있는 5개 SKYNET 관측소(서울, 지바, 엣추 지마, 후쿠에 지마, 헤도 미사키)에서 6년 간 관측한 AOT 자료를 활용하여 MODIS에서 산출된 AOT를 검증하였고, 아울러 에어로솔 기후장 분석도 함께 수행하였다. 검증연구를 위해 관측소 25 km 이내의 MODIS AOT를 평균하였고, MODIS 관측시각 30분 전후 SKYNET AOT를 평균하여 시공간 일치 자료를 생산하였다. 시공간 일치 자료의 비교 결과 MODIS AOT의 정확도는 에어로솔 종류에 크게 영향을 받지 않았으나, MODIS AOT 산출과정 중 거대 입자 모형의 사용비율이 높아질수록 SKYNET AOT에 비해서 비교적 큰 값을 산출하는 경향을 보였다. 또한 AOT가 낮은 대기에서 MODIS AOT는 과대 추정하는 경향을 보였고 그 경향성은 AOT가 높아질수록 줄어들었다. MODIS-SKYNET AOT간의 회귀분석 결과 기울기는 0.86, Y절편은 0.16으로 나타났고 결정계수($R^2$)는 0.61로 나타났다. 이러한 통계적 결과로 미루어 볼 때 동아시아 영역에서 산출된 MODIS AOT는 지상 관측에 견줄 만큼 정확하다고 볼 수 있다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 하계학술발표대회
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• pp.150-150
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• 2005

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 하계학술발표대회 논문집
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• pp.209-209
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• 2007

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.381-384
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• 2005

We have applied the TOMS aerosols retrieval algorithm to GLI measurements. TOMS has utilized the aerosol index, which is a measure of the change in spectral contrast due to the wavelength-dependent effects of aerosols. We have retrieved the GLI aerosol index, which is made by the pair of 380/400nm, 380/412nm, 380/460nm, and 412/460nm. We have found that the biomass burning aerosols represent the absorbing aerosols. In addition, the pair of 380/460nm has shown the best signal for detecting aerosols in Principal Component Analysis(PCA) and comparison of aerosol optical thickness from AERONET data. The theoretical aerosol index is also shown the best signal in the pair of 380/460nm.

• 대한기계학회논문집B
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• 제23권2호
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• pp.262-271
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• 1999

A study of aerosol dynamics has been done to obtain axially and radially varying size distributions of particles generated in the Modified Chemical Vapor Deposition process. Heat and mass transfer have also been studied since particle generation and deposition strongly depend on the temperature field in a tube. Bimodal size distributions of particles have been obtained both in the particulate flow and in the deposited particle layer for the first time using the sectional method to solve aerosol dynamics. Variations of geometric mean diameter, geometric standard deviation have been studied for various parameters; flow rates and maximum wall temperature. The comparison between one-dimensional and two-dimensional approaches has also been made.