• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.81-82
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• 2003

제주도 서단의 고산 상층기상대는 한반도와 중국대륙, 그리고 대양으로부터의 물질이동의 중간 경로에 위치한 지리적인 요인에 의하여, 동아시아 지역의 대기오염물질의 특성을 파악하기 유리한 장소라 할 수 있다. 2001년부터 계절에 따라 이 지역에서 Micro Pulse Lidar(MPL)를 이용한 에어러솔 관측이 수행되었고, sunphotometer 관측도 병행되어 에어러솔의 공간분포 및 광학적 특성을 파악할 수 있었다. (중략)

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.4
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• pp.319-329
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• 2015

The characteristics of aerosol light extinction were investigated by comparing measured and calculated extinction coefficient to understand the contribution of air pollutants on visibility impairment for data during 4 months (Jan~ April), 2014. The integrated nephelometer and aethalometer system were installed to measure the scattering and absorption coefficients of aerosol as well as BAM 1020, MARGA, semi-continuous OCEC analyzer, and online-XRF to calculate the extinction coefficient. The IMPROVE_2005 equation was used to determine the contributions of different chemical components on visibility impairment in $PM_{2.5}$ and $PM_{10}$ due to highest correlation with measured data. Sulfate, nitrate, and organic mass by carbon (OMC) of fine aerosol were the major contributors affecting on visibility impairment. Total contributions to light extinction were calculated as $631.0Mm^{-1}$ for the worst-case and $64.4Mm^{-1}$ for the best-case. The concentrations of aerosol component for the worst-case were 38.4 times and 45.5 times larger than those of the best-case for $(NH_4)_2SO_4$ and $NH_4NO_3$, respectively. At lower visibility condition, in which extinction coefficient was higher than $400Mm^{-1}$, extinction coefficient varied according to the relative humidity variation regardless of $PM_{2.5}$.

• Korean Journal of Remote Sensing
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• v.30 no.1
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• pp.47-59
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• 2014

Volcanic ash (VA) can be estimated by remote sensing sensors through their spectral signatures determined by the inherent optical property (IOP) including complex refractive index and the scattering properties. Until now, a very limited range of VA refractive indices has been reported and the VA from each volcanic eruption has a different composition. To improve the robustness of VA remote sensing, there is a need to understanding of VA - radiation interactions. In this study, we calculated extinction coefficient, scattering phase function, asymmetry factor, and single scattering albedo which show different values between andesite and pumice. Then, IOPs were used to analyze the relationship between theoretical remote sensed radiation calculated by radiative transfer model under various aerosol optical thickness (${\tau}$) and sun-sensor geometries and characteristics of VA. It was found that the mean rate of change of radiance at top of atmosphere versus ${\tau}$ is six times larger than in radiance values at 0.55 ${\mu}m$. At the surface, positive correlation dominates when ${\tau}$ <1, but negative correlation dominates when ${\tau}$ >1. However, radiance differences between andesite and pumice at 11 ${\mu}m$ are very small. These differences between two VA types are expressed as the polynomial regression functions and that increase as VA optical thickness increases. Finally, these results would allow VA to be better characterized by remote sensing sensors.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.2
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• pp.139-149
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• 2014

A new technique, namely the combination of satellite and trajectory analysis (CSTA), for exploring the spatio-temporal distribution information of volcanic ash plume (VAP) from volcanic eruption. CSTA uses the satellite derived ash property data and a matching forward-trajectories, which can generate airmass history pattern for specific VAP. In detail, VAP properties such as ash mask, aerosol optical thickness at 11 ${\mu}m$ ($AOT_{11}$), ash layer height, and effective radius from the Moderate Resolution Imaging Spectro-radiometer (MODIS) satellite were retrieved, and used to estimate the possibility of the ash forecasting in local atmosphere near volcano. The use of CSTA for Iceland's Eyjafjallaj$\ddot{o}$kull volcano erupted in May 2010 reveals remarkable spatial coherence for some VAP source-transport pattern. The CSTA forecasted points of VAP are consistent with the area of MODIS retrieved VAP. The success rate of the 24 hour VAP forecast result was about 77.8% in this study. Finally, the use of CSTA could provide promising results for VAP monitoring and forecasting by satellite observation data and verification with long term measurement dataset.

• Ocean and Polar Research
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• v.25 no.1
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• pp.9-20
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• 2003

A solar radiation model was used to investigate the UV radiation at the surface offing Sejong Station in West Antarctica. The results calculated by this model were compared with the values measured by UV-Biometer and UV-A meter during 1999-2000. In this study, the parameterization of solar radiative transfer process was based on Chou and Lee(1996). The total ozone amounts measured by Breve. Ozone Spectrophotometer and the aerosol amounts by Nakajima et al.(1996) was used as the input data of the solar radiative transfer model. And the surface albedo is assumed to be 0.20 in summer and 0.85 in winter. The sensitivity test of solar radiative transfer model was done with the variation of total ozone, aerosol amount, and surface albedo. When the cosine of solar zenith angle is 0.3, Erythemal UV-B radiation decreased 73% with the 200% increase of total ozone from 100 DU to 300 DU, but the decrease of UV-A radiation is about 1%. Also, for the same solar zenith angle, UV-A radiation was decreased 31.0% with the variation of aerosol optical thickness from 0.0 to 0.3 and Erythemal UV-B radiation was decreased only 6.1%. The increase of Erythemal W-B radiation with the variation of surface albedo was twice that of UV-A increase. The surface Erythemal UV-B and UV-A radiation calculated by solar raditive transfer model were compared with the measured values fer the relatively clear day at King Sejong Station in West Antarctica. The model calculated Erythemal UV-B radiation at the surface coincide well with the measured values except for cloudy days. But the difference between the model calculated UV-A radiation and the measured value at the surface was large because of cloud scattering effect. So, the cloud property data is needed to calculate the UV radiation more exactly at King Sejong Station in West Antarctica.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.531-540
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• 2019

Hydrophilic and hydrophobic nanosilica and tetraethyl orthosilicate (TEOS) as a coupling agent was used to form a coarse spike structure as well as an excellent reactive hydroxyl groups on the glass surface. Then, a second treatment was carried out using a trichloro-(1H,1H,2H,2H)perfluorooctylsilane(TPFOS) solution for ultimate water repellent glass surface formation. The formation of hydrophobic coating layer on glass surface using silica aerosol, which is hydrophobic nanosilica, was not able to form a durable hydrophobic coating layer due to the absence of reactive -OH groups on the surface of nanosilica. On the other hand, a glass surface was first coated with a coating liquid prepared with hydrophilic hydroxyl group-containing nanosilica and hydrolyzed TEOS, and then coated with a TPFOS solution to introduce a hydrophobic surface on glass having a water contact angle of $150^{\circ}$ or more. The sliding angle of the coated glass was less than $1^{\circ}$, which meant the surface had a super water-repellent property. In addition, as the content of hydrophilic nanosilica increased, the optical transmittance decreased and the optical transmittance also decreased after 2nd coating with the TPFOS solution. The super-hydrophobic property of the coated glass was remained up to 50 times of rubbing durability test, but only hydrophobic property was shown after 200 times of rubbing durability test. Conclusively, the optimal coating conditions was double 1st coatings with the HP3 coating solution having a hydrophilic nanosilica content of 0.3 g, and subsequent 2nd coating with the TPFOS solution. It is believed that the coating solution thus prepared can be used as a surface treatment agent for solar cells where light transmittance is also important.