• Journal of Korean Society for Atmospheric Environment
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• v.19 no.2
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• pp.167-177
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• 2003

The number size distribution of urban aerosols ranging from 0.02 to 20 ${\mu}{\textrm}{m}$ in diameter was measured by using a scanning mobility particle sizer (SMPS) system and an aerodynamic particle sizer spectrometer (APS) at Seoul from November 30,2001 to January 14, 2002. The gaseous species such as CO, NO, NO$_2$, and $O_3$ were also continuously monitored. The daily average concentration of urban aerosols sorted into three groups (0.02~0.1 ${\mu}{\textrm}{m}$, 0.1~1 ${\mu}{\textrm}{m}$ and 1~10 ${\mu}{\textrm}{m}$) and the typical number, surface, and volume distributions of urban aerosols were discussed in this paper. The weekly variation of aerosol concentration was compared with those of gaseous concentrations. relative humidity, and visibility. The results showed that the particle number concentration seemed to increase in the morning and the number concentration of fine particles less than 1 fm in diameter seemed to increase when the concentrations of CO, NO, and NO$_2$ were high. The number concentration of fine particles was relatively high when the relative humidity was greater than 70％ during the increasing period of relative humidity. The visibility was weakly correlated with the concentration of aerosols ranging 0.1 to 1 ${\mu}{\textrm}{m}$, and the number size distribution for high visibility episode was apparently different from that for low visibility episode.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.251-252
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• 2003

Most particles capable of reaching the thoracic region of humans are in the size range below 10$\mu$m in diameter. Particles with a diameter smaller than 2.5 $\mu$m are deposited in large amounts in the alveolar region during mouth inhalation. The hazard caused by fine particles depends on their chemical composition and the site within the human respiratory system where they are deposited(Hinds, 1982). Therefore, the concentration of air borne fine particles is an important parameter for the evaluation of the degree of hazard in an atmospheric environment. (omitted)

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.6
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• pp.803-810
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• 2004

Water contents in fine particles at Seoul and Gosan are estimated by using a gas/particle equilibrium model, SCAPE (Simulating Composition of Atmospheric Particles at Equilibrium). Also, sensitivity of particulate inorganic ionic concentrations on the total ionic species is estimated. Water content at Gosan is more sensitive to ambient relative humidity (RH) than Seoul. At both sites water content is most sensitive to sulfate concentration among sulfate, nitrate, and ammonium. Solid salts levels and compositions are also studied.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.5
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• pp.656-667
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• 2013

The non-exhaust coarse, fine, and ultrafine particles were characterized by on-road driving measurements using a mobile sampling system. The on-road driving measurements under constant speed driving revealed that mass concentrations of roadway particles (RWPs) were distributed mainly in a size range of 2~3 ${\mu}m$ and slightly increased with increasing vehicle speed. Under braking conditions, the mode diameters of the particles were generally similar with those obtained under constant speed conditions. However, the PM concentrations emitted during braking condition were significantly higher than those produced under normal driving conditions. Higher number concentrations of ultrafine particles smaller than 70 nm were observed during braking conditions, and the number concentration of particles sampled 90 mm above the pavement was 6 times higher than that obtained 40 mm above the pavement. Under cornering conditions, the number concentrations of RWPs sampled 40 mm above the pavement surface were higher than those sampled 90 mm above the pavement. This might be explained that a nucleation burst of a lot of vapor evaporated from the interaction between the tire and the road pavement under braking conditions continuously occurred by cooling during the transport to the sampling height 90 mm, while, for the case of cornering situations, the ultrafine particle formation was completed before the transport to the sampling height of 40 mm.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.393-398
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• 2005

Suspended fine mineral particles are deposited at the areas with low flow velocity and low transportation capacity in rivers, reservoirs and lakes. It can be contaminated by heavy metals. Examples of problem fields art dredging of sediment, water pollutants, and maintenance of navigation channels and construction works. To deal with the settling problems it is necessary to understand tile physico-chemical characteristics of cohesive sediment under varying density of particle and ion addition(NaOH, HCl, NaCl), which is dissolved in river, because fine-grained cohesive sediment can lead to flocculation with the physico-chemical influences and takes different characteristics. Experiments with fresh and saline water are followed with fine-grained sediments(alumina and quartz) in settling columns. Settling velocity of suspended fine particles in still water was measured with a pressure sensor(maximum 10 mbar). Until the initial concentration of 20,000 mg/1 of alumina and quartz the settling velocity was on the increase. Above this initial concentration was it on the decrease. In an acid condition, which causes strong flocculation, average settling velocity of quartz powder was high. In an alkaline water low average settling velocity of it was observed. However, alumina behaved exactly contrarily.

• Journal of Environmental Science International
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• v.19 no.3
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• pp.331-342
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• 2010

Aerosol physical properties have been measured at Pusan National University by using the 16-channel LPC(Laser Particle Counter), and particle characteristics have been examined for the period from Aug. 4 2007 to Dec. 30, 2008. Annual total average, seasonal average, and other averages of the meteorologically classified four categories such as Asian dust, precipitation, foggy, and clear days are respectively described here. Both annually and seasonally averaged number concentration show three peaks at the particle diameter of 0.3, 1.3, and $4{\mu}m$, respectively. However, the first peak for summer season tends to be shifted toward smaller size than other seasons, implying the strong fine particle generation. Meteorological condition shows strong contrast in aerosol concentrations. In Asian dust case, relatively lower number concentrations of fine particles (i.e., smaller than $0.5{\mu}m$) were predominant, while higher concentrations of coarse particles were found particularly for the size bigger than $0.5{\mu}m$. In precipitation day, number concentrations were decreased by approximately 30% due to the removal process of precipitation. Foggy day shows significantly higher concentrations for fine particles, implying the importance of the aerosol condensation process of micro-fine-particle growing to fine-particle. Finally the regressed particle size distribution function was fitted optimally with two log-normal distribution, and discussed the similarities and differences among four categorized cases of the Asian dust, precipitation, foggy, and clear days.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.6
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• pp.666-674
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• 2012

The purpose of this study is to propose management strategies to lower the level of $PM_{10}$ concentration. First, this study analyzes the characteristics of particle sizes in three different areas, the residential, the roadside, and the industrial areas. Second, it has examined the size of particles which can influence on the increase of $PM_{10}$ concentration level. The distribution of particle size for $PM_{10}$ concentration was not different by regions. The highest portion in the observed $PM_{10}$ is near $0.3{\mu}m$. In addition, both near $2.5{\mu}m$ and near $5.0{\mu}m$ are found higher in portion. The fractions of $PM_{1.0}$ and $PM_{2.5}$ in $PM_{10}$ are 68.2% and 75.8% respectively. The fraction of $PM_{1.0}$ in $PM_{2.5}$ is 89.8%. The particle diameters contributed to the increase of $PM_{10}$ concentration are different by regions. In the residential area, the sizes of near $0.6{\mu}m$ and near $3.3{\mu}m$ particles are found to be the cause for the increase of $PM_{10}$ concentration level. However the particle sizes for the increase of $PM_{10}$ concentration level are $0.8{\mu}m$ and $0.5{\mu}m$ in roadside and industrial area respectively. Therefore, fine particles are found as the key factors to raise $PM_{10}$ concentration level in the two areas, while both fine and coarse particles are in the residential areas. When examined the $PM_{10}$ concentration level change, it was categorized by two different time zones, the high concentration level time and the lower concentration time. In high concentration time, the $PM_{10}$ concentration has increased in the morning in the residential and roadside areas. On the contrary, the level has increased in the evening in the industrial area. In low concentration time, the level of $PM_{10}$ concentration in the roadside area is significantly higher in the morning than the concentration level of other times. There is no significantly different concentration level found in the both residential and industrial areas throughout the day.

• YAKHAK HOEJI
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• v.32 no.5
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• pp.362-369
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• 1988

Monthly variation of mutagenicity by airborne particulate were studied according to particle size of the particulate. Airborne particulates were collected in Shinchon of Seoul which is commocial and traffic area in 1986. And those were separately collected into two parts such as fine particle (less than $2.5{\mu}m$ aerodynamic diameter) and coarse particle (greater than $2.5{\mu}m$). Extractable organic matters(EOM) were extracted and mutagenicity of the EOM was tested in Salmonella thyphimurium TA 98 by Ames method. While the concentration of coarse particle did not show the seasonal variation, that of fine particle showed great seasonal variation. The contents and mutagenicity of EOM in fine particles were higher than those of coarse particles. So fine particles were expected to contribute to the 90% of mutagenicity in atmosphere by suspended particulates. The content of EOM and mutagenicity by suspended particulates in atmosphere were highest in January all the year around and also higher as much as 6 and 30 times than in July, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E3
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• pp.99-120
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• 2003

Visibility impairment in an urban area is mainly caused by airborne fine particulate matters. Visibility in a clean air environment is more sensitive to the change of PM$_{2.5}$ particle concentrations. However, a proportionally larger reduction in fine particle concentration is needed to achieve a small increment of visibility improvement in polluted areas. Continuous optical monitoring of atmospheric visibility and extensive aerosol measurements have been made in the urban atmosphere of Kwangju, Korea. The mean for fine particulate mass from 1999 to 2002 at Kwangju was measured to be 23.6$\pm$20.3 $\mu\textrm{g}$/㎥. The daily average seasonal visual range was measured to be 13.1, 9.2, 11.0, and 13.9 km in spring, summer, fall, and winter, respectively. The mean light extinction budgets by sulfate, nitrate, organic carbon, and elemental carbon aerosol were observed to be 27, 14, 22, and 12%, respectively. It is highly recommended that a new visibility standard and/or a fine particle standard be established in order to protect the health and welfare of general public. Much more work needs to be done in visibility studies, including long-term monitoring of visibility, improvement of visibility models, and formulating integrated strategies for managing fine particles to mitigate the visibility impairment and climate change.e.

• Resources Recycling
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• v.14 no.1
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• pp.26-32
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• 2005

A study on the preparation of Ag fine particles was performed through a reduction reaction using ascorbic acids as a reductant, which is one of the indispensable processes for the recycling of silver-bearing wastes. Silver nitrate solution in the range of 10~120 mmole/l was used and Tamol NN8906 or PVP was also used as a dispersant in the preparation of Ag fine particles size analyze, SEM, and TEM to determine the particle size and morphology of them. As a result, the reduction reaction of silver ions with ascorbic acid reached equilibrium within 10 min. It was found that about 60% excess of ascorbic acid was required in order to reduce completely silver ions in the solution. The particle size distribution of Ag particles prepared through the reduction reaction showed typically biomodal or trimodal distribution. Especially, initial Ag concentration in the solution, the type and amount of dispersant added during the reduction reaction played an important role in determining the mean particle size of Ag particles.