• Korean Journal of Remote Sensing
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• v.26 no.6
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• pp.605-615
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• 2010

This study demonstrates the feasibility of small satellite, namely PROBA platform with the compact high resolution imaging spectrometer (CHRIS), for aerosol retrieval in Hong Kong. The rationale of our technique is to estimate the aerosol reflectances by decomposing the Top of Atmosphere (TOA) reflectances from surface reflectance and Rayleigh path reflectances. For the determination of surface reflectances, the modified Minimum Reflectance Technique (MRT) is used on three winter ortho-rectified CHRIS images: Dec-18-2005, Feb-07-2006, Nov-09-2006. For validation purpose, MRT image was compared with ground based multispectral radiometer measurements and atmospherically corrected Landsat image. Results show good agreements between CHRIS-derived surface reflectance and both by ground measurement data as well as by Landsat image (r>0.84). The Root-Mean-Square Errors (RMSE) at 485, 551 and 660nm are 0.99%, 1.19%, and 1.53%, respectively. For aerosol retrieval, Look Up Tables (LUT) which are aerosol reflectances as a function of various AOT values were calculated by SBDART code with AERONET inversion products. The CHRIS derived Aerosol Optical Thickness (AOT) images were then validated with AERONET sunphotometer measurements and the differences are 0.05~0.11 (error=10~18%) at 440nm wavelength. The errors are relatively small compared to those from the operational moderate resolution imaging spectroradiometer (MODIS) Deep Blue algorithm (within 30%) and MODIS ocean algorithm (within 20%).

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.61-68
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• 1997

The morphology and size distribution of chromium oxides and the concentration measurement of atomic arsenic have been studied in laminar diffusion flames. Nitrogen was added to vary flame temperatures in hydrogen flames. Ethene flames were used in order to investigate the potential for interaction between the soot aerosol that is formed in these flames and the chromium aerosol. Two sources of chromium compounds were introduced: chromium nitrate and chromium hexacarbonyl. A detailed investigation of the morphology was carried out by scanning electron microscopy (SEM). The amounts of Cr(VI) and total Cr were determined by a spectrophotometric method and by X-ray fluorescence spectrometry, respectively. Also, LIF was used for the measurement of atomic arsenic, which was excited at 197.2 nm and was detected at 249.6 nm. Results showed that the morphology of the particles varied with the flame temperature and with the chromium source. The particles were characterized by porous structures, cenospheres and agglomerated dense particles when chromium nitrate solution was added to the flames. At low to moderate temperatures, porous sintered cenospheric structures were formed, in some cases with a blow hole. At higher temperatures, an agglomerated cluster which was composed of loosely sintered submicron particles was observed. It was also found that the emission of Cr(VI) from the undiluted $H_2$ flame was more than 10 times larger than in the 50% $H_2$ / 50% $N_2$ flame on a mass basis. Single point LIF measurement of atomic arsenic indicated that arsenic exist only in the low temperature, fuel rich region.

• Particle and aerosol research
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• v.12 no.1
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• pp.21-26
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• 2016

In order to realize In-line and convenient measurement for solid-gas two phase flows, Light Transmission Fluctuation (LTF) based on the random variation of transmitted light intensity, light scattering theory and cross-correlation method was presented for online measurement of particle size, concentration and velocity. The statistical relationship among transmitted light intensity, particle size and particle number in measurement zone was described by Beer-Lambert Law. Accordingly, the particle size and concentration were determined from the fluctuation signal of transmitted light intensity. Simultaneously, the particle velocity was calculated by cross-correlation analysis of two neighboring light beams. By considering the influence of concentration variation in industrial applications, the improved algorithm based on spectral analysis of transmitted light intensity was proposed to improve measurement accuracy and stability. Therefore, the online measurement system based on LTF was developed and applied to measure pulverized coal in power station and raw material in cement plant. The particle size, concentration and velocity of powder were monitored in real-time. It can provide important references for optimal control, energy saving and emission reduction of energy-intensive industries.

• Particle and aerosol research
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• v.9 no.1
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• pp.1-6
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• 2013

New evaluation method for the particle size and morphology via change of ground particle during a grinding process was investigated. The grinding experiments were carried by a planetary ball mill. The relationship between the particle outline of the scanning electron microscopy photograph and measurement line, the measurement contact number was evaluated. The value of contact number decreased with the increase in the particle size of the ground sample, and varied with the experimental conditions. The value of contact number, which is related to the particle size of the raw sample, changed at the various experimental conditions.

• Particle and aerosol research
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• v.4 no.2
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• pp.69-75
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• 2008

Nanosize ZnO particles were prepared by oxidation of zinc vapor and the particle growth was modeled by a coagulation model by assuming that the characteristic time for reaction was much shorter than coagulation time and residence time (${\tau}_{reaction}{\ll}{\tau}_{coagulation}{\ll}{\tau}_{residence}$). Experimental measurement of zinc oxide particles diameter was consistent with the predicted result from the coagulation model. For practical purpose of predicting zinc oxide size in areosol reactor, the constant kernel solution is concluded to be sufficient, Uniqueness of nano-scale property of zinc oxide was confirmed by the higher photocatalytic activity of zinc oxide than nanosize titania particles.

• Particle and aerosol research
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• v.13 no.4
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• pp.165-172
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• 2017

For precise particle measurements in combustion environments, various dilution sampling methods were compared. Dilution equipments using dilution tunnels and hot/cold dilution with porous tube dilutors were most frequently used so far. The combination of porous tube dilutor and ejector diluter has relatively small footprint, and it results in lower particle losses compared to other methods. To determine the portion of condensable particulate matter, proper temperature control and flow control is required.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.315-316
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• 2005

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.518-519
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• 2005

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.10a
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• pp.264-265
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• 2008

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.334-335
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• 2005