• Particle and aerosol research
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• v.9 no.4
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• pp.221-230
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• 2013

We demonstrated the efficacy of magnetic nanoparticles (MNPs) produced from a low grade iron ore as an adsorbent for the removal of Cr(VI), a toxic heavy metal anion present in wastewater. The adsorption of Cr(VI) by these MNPs strongly depended on the dosage of MNPs, the initial concentration of the Cr(VI) solutions, and pH. The highest Cr(VI) adsorption efficiency of 22.0 mg/g was observed at pH 2.5. The adsorption data were best fit with the Langmuir isotherm and corresponded to a pseudo-second-order kinetic model. The used adsorbent was regenerated by eluting in highly alkaline solutions. Sodium bicarbonate showed the highest desorption efficiency of 83.1% among various eluents including NaOH, $Na_2HPO_4$, and $Na_2CO_3$. Due to the high adsorption capacity, the simple magnetic separation, and the high desorption efficiency, this nano-adsorbent produced from inexpensive and abundant resources may attract the attention of the industries to apply for removing various metal anionic contaminants from wastewater.

• Korean Journal of Remote Sensing
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• v.29 no.6
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• pp.663-670
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• 2013

Total Vertical Column Density (VCD) of $NO_2$, a key component in air quality and tropospheric chemistry was measured using a ground-based instrument, Pandora, in Seoul from March 2012 to October 2013. The $NO_2$ measurements using Pandora were compared with those obtained by satellite remote sensing from Ozone Monitoring Instrument (OMI) where the intercomparison characteristics were analyzed as a function of measurement geometry, cloud amount and aerosol loading. The negative biases of the OMI $NO_2$ VCD were larger when cloud amount and Aerosol Optical Depth (AOD) were higher. The correlation coefficient between $NO_2$ VCDs from Pandora and OMI was 0.53 for the entire measurement period, whereas the correlation coefficient between the two was 0.74 when the cloud amount and AOD were low (cloud amount<3, AOD<0.4). The low bias of OMI data was associated with the shielding effect of the cloud and the aerosols.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.2
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• pp.167-177
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• 1996

To investigate the source-receptor relationships aerosol model has been used to simulate the distribution behavior of the yellow sand. Data for meteorological fields were obtained by Meso-scale Analysis and Prediction Model System/Seoul National University (MAPMS/SNU) for five days (10-14 April 1988). To obtain the distributions of concentration of yellow sand,the aerosol model has been modified to allow quantifications of relative concentration distributions of yellow sand. Source regions of yellow sand were delineated by soil maps of China and emission rate as a function of wind stress(Westphal et al., 1987). Using 3-dimensional wind fields the backward trajectories from 3 receptor grids at the layer of .sigma. =0.95, 0.9, 0.85, 0.8 were calculated. In order to facilitate quantitative assessment of source-receptor relationships, it was assumed that the perturbations in along-trajectory and cross-trajectory proceed linearly with time, in accord with Gaussian distribution characteristics. On the basis of this assumption, the probability fields were calculated from every grid point with source strength 1. Using these probability fields and emission retes, the potential contributions of upstream sources along the trajectories were estimated. The results of this study indicate that the application of trajectory modeling is useful in investigating the quantitative relationship between source and receptor regions.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.2
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• pp.179-192
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• 2001

In order to characterize the distribution patterns of PAHs between Yellow Sand (YS) and non-Yellow Sand(NYS) periods, we collected and analyzed aerosol samples for PAHs for the periods covering 28 March through 24 April 2000. The concentrations of TSP measured during the YS periods were approximately two times higher than the NYS periods. By contrast, the concentrations of PAHs during YS were higher than those of NYS by 140%. In ad-dition, their concentrations in PM 10 were larger than those TSP by 120% . Detailed inspections of our data indi-catd that three species including chrysene. benzo(b)fluoranthene, and benzo(k)fluoranthene were effeciently ad-sorbed by particles less than 10${\mu}{\textrm}{m}$ diameter and that there were dominating the distribution characterstics of PAHs during the YS periods. Results of correlation analysis also indicated that PAHs exhibited strong correlations with those pollutants originating from combustion sources. It is thus concluded that pollutants such as toxic PAHs that originate from diverse anthropogenic sources of China should be contributing to the degradation of the ambient air quality in Seoul.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.1
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• pp.41-49
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• 2014

Pig chronic wasting disease, including porcine reproductive and respiratory syndrome (PRRS) and postweaning multisystemic wasting syndrome (PMWS), have made a continuous economic damage in pig farms. Airborne spread of livestock viruses are an important spread factor which is difficult to analyze due to invisible airflow and limitation of measurement. The objective of this study is to analyze airborne disease spread between buildings in the experimental pig farm by means of field experiment and computational fluid dynamics (CFD). The field experiments were conducted to capture airborne virus using air sampler and teflon filter along multi points in the experimental pig farm. The samples were tested in terms of virus detection resulting in positive reaction for PRRS and PCV-2 viruses, which can be a firm evidence of airborne virus spread. The CFD simulation model was developed by considering complex topography, wind conditions, building arrangement, and ventilation systems and was used to analyze airborne virus spread according to different wind conditions. The CFD computed result showed a possibility of airborne virus spread via livestock aerosol from infected pig house to neighboring pig houses according to wind directions. The CFD simulation technique is expected to provide significant data for estimating and making a counterplan against airborne disease spread.

• Proceedings of the KSRS Conference
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• v.1
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• pp.305-307
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• 2006

A multi-spectral photometer was set up as an NASA/AERONET site at Kinki University campus in Higashi-Osaka in 2002 for measuring urban aerosols. In addition, the SPM-613D (Kimoto Electric) commenced measurement of suspended particles matter (SPM) as $PM_{10}$ and $PM_{2.5}$ on March 15, 2004 at the same AERONET site. The obtained results revealed that the poor air quality of the Higashi-Osaka site is due not only to anthropogenic particles from local emissions, such as diesel vehicles and chemical industries, but also to dust particles brought from continental desert areas by large scale climatic conditions. To understand the characteristics of background atmosphere over Higashi-Osaka, we examined the relationship between $PM_{2.5}$ concentration and aerosol optical thickness (AOT) at a wavelength of 0.87 μm based on AERONET data for background atmosphere (AOT<0.2). We obtained a linear regression line between AOT and $PM_{2.5}$ concentration. Using the linear relationships between AOT and $PM_{2.5}$, we show ground-level concentrations of $PM_{2.5}$ of background atmosphere from Terra/MODIS satellite measurements.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.5
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• pp.424-432
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• 2002

Numerical analysis has been conducted to characterize deposition rates of aerosol particles onto a heated, rotating disk with electrostatic effect under the laminar flow field. The particle transport mechanisms considered were convection, Brownian diffusion, gravitational settling, thermophoresis and electrophoresis. The aerosol particles were assumed to have a Boltzmann charge distribution. The electric potential distribution needed to calculate local electric fields around the disk was calculated from the Laplace equation. The Coulomb, the image, the dielectrophoretic and the dipole-dipole forces acting on a charged particle near the conducting rotating disk were included in the analysis. The averaged particle deposition vetocities and their radial distributions on the upper surface of the disk were calculated from the particle concentration equation in a Eulerian frame of reference, along with a rotation speed of 0∼1,000rpm, a temperature difference of 0∼5K and a charged disk voltage of 0∼1000V.Finally, an approximate deposition velocity model for the rotating disk was suggested. The present numerical results showed relatively good agreement with the results of the present approximate model and the available experimental data.

• Particle and aerosol research
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• v.5 no.4
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• pp.179-188
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• 2009

The dry deposition fluxes of particulate polychlorinated biphenyls (PCBs) were measured along with their mass size distributions at Seoul and Incheon in fall in 1999. The dry deposition fluxes of PCBs were in the range of $16.7{\sim}62.2ng/m^2/day$. The ambient concentrations of particulate PCBs were in the range of 0.07 to $0.20ng/m^3$. Generally, the mass size distribution of particulate PCBs shows bi-modal distribution. The mass fraction of PCBs in the fine particle fraction ($D_p<2.1 {\mu}m$) was over than 55% of the total PCBs concentrations. It was found that Seoul and Incheon were not the major source of PCBs emissions in Korea. Based on the comparison with the measurement data in summer, 1999, it is likely that both the dry deposition fluxes and ambient particulate PCBs concentrations were not site-specific.

• Particle and aerosol research
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• v.15 no.4
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• pp.149-157
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• 2019

Infiltration characteristics of airborne particulate matter had been investigated in real-life for about 90 days over 2 years in a Korean apartment building where a 3-person household had lived and the exclusive private area was 84.9 ㎡. Airtightness was measured by fan depressurization, and the ACH₅₀ was 2.41 times per hour. In and outdoor particle concentrations were measured by optical particle counters. Infiltration factors and filtration efficiencies of the house, which reflect the removal of outdoor particles penetrating building envelope and the deposition inside a building, were obtained from data screened based on an empirical evaluation process. Infiltration factor of fine particles showed a range from about 42% at 0.4 m/s of wind speed to 72% at 4.2 m/s of wind speed with closed windows and doors. Filtration efficiency was like a MERV 13 grade filter with an open window outside at a balcony at low outdoor wind speed under 1 m/s. The grade decreased to MERV 11 by opening another outside window at the other balcony. Filtration efficiencies decreased as much as 29% in average at a range of 0.3~2.5 ㎛.

• Asian Journal of Atmospheric Environment
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• v.9 no.2
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• pp.137-145
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• 2015

This study focused on the measurement of the actual charging state of ambient aerosol particles, which is important for understanding the intricate process of adverse health effects caused by particulate matter (PM). The net electrostatic charging state of $PM_{2.5}$ collected on filter media was measured in this study. The Faraday cage method and surface potential measurements were used in this study. The results showed that the polarities of the net charging state measured using these two methods were in agreement for 42 out of 48 samples (87.5%), and 36 samples (75%) were negatively charged. The filters were not significantly charged by friction between the filters and air not containing PM. Charge addition to or leakage from the filters was not observed over a two-month storage period. Net charging state of $PM_{2.5}$ collected on the filters was concluded to be negative in most cases, based on data's support of the assumption that aerosol charging state is not altered by the process of PM collection using filter.