• Journal of Korean Society for Atmospheric Environment
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• v.27 no.3
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• pp.272-280
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• 2011

A novel particle removal system for air handling unit (AHU) of subway station was evaluated experimentally. The novel system was designed in order to minimize the maintenance cost by applying axial-flow cyclones. The system consists of multiple cyclone units and dust trap. Based on our previous numerical study, it was found to be effective for removal $1\sim10{\mu}m$ sized dust particles. In this study, we manufactured the mock-up model and evaluated the model experimentally. Liquid and solid test particles were generated for evaluating collection efficiency of the system and the pressure drop was monitored. The collection efficiency was varied from 41.2% to 85.9% with increasing the sizes of particle from 1 to $6.5{\mu}m$ by particle count ratio of inlet and outlet. The pressure drop was maintained constant less than $20mmH_2O$. In addition, the collection efficiency was estimated by total mass for solid test particles. It was found that the collection efficiency was 65.7% by particle mass ratio of inlet and outlet. It shows that present system can replace current pre-filters used in subway HVAC system for removing particulate matters with minimal operational cost.

• Journal of Korean Society for Atmospheric Environment
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• v.10 no.1
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• pp.57-63
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• 1994

In order to comprehension of the behaviour of PAHs in air which is known as carcinogens and/or mutagens suspended Particulates in ambient air were collected by Anderson air sampler from 1992. 6 to 1993. 5 in Seoul. Ten species of PAHs( Phen, An, Fl, R, Py, BaAn, BaP, Chry, BeP, DiB(a, h)An, I123p) were analyzed to understand monthly variations of PAHs distribution of PAHs concentration according to particle size, and correlation between PAHs and independent charactierstics of PAHs The highest concentration of TSP was 155.58$\mu\textrm{g}$/㎥ in May and the lowest was 60$\mu\textrm{g}$/㎥ in August. Concentration of TSP was more affected by coarse particles in spring, otherwise which was more affected by fine particles in winter. According to results of anaylsis of samples that were collected by Anderson air sampler, concentration of PAHs was more high in winter than that in summer. In almost samples collected by Anderson air sampler, concentration of PAHs was more high in coarse particles than in fine particles, but BaP well known as carcinogenic matter had more high concentration in fine particles(56-97.5%) than that in coarse particles(2.5-46%). Correlation between concentrations of TSP and PAHs was more high in fine Particles than in coarse Particles. Both fine particles and coarse particles have negative correaltion with radiation.

• Particle and aerosol research
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• v.17 no.3
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• pp.43-54
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• 2021

Size distributions of atmospheric particulate matter (PM) and its water-soluble organic and inorganic components were measured between January and February 2021 at an urban site in Gwangju in order to identify the major factors that determine their size distributions. Their size distributions during the study period were mainly divided into two groups. In the first group, PM, NO₃^-, SO₄^2-, NH₄⁺ and water-soluble organic carbon (WSOC) exhibited bi-modal size distributions with a dominant condensation mode at a particle size of 0.32 ㎛. This group was dominated by local production of secondary water-soluble components under atmospheric stagnation and low relative humidity (RH) conditions, rather than long-range transportation of aerosol particles from China. On the other hand, in the second group, they showed tri-modal size distributions with a very pronounced droplet mode at a diameter of 1.0 ㎛. These size distributions were attributable to the local generation and accumulation of secondary aerosol particles under atmospheric conditions such as atmospheric stagnation and high RH, and an increase in the influx of atmospheric aerosol particles by long-distance transportation abroad. Contributions of droplet mode NO₃^-, SO₄^2-, NH₄⁺ and WSOC to fine particles in the second group were significantly higher than those in the first group period. However, their condensation mode contributions were about two-fold higher in the first group than in the second group. The significant difference in the size distribution of the accumulation mode of the WSOC and secondary ionic components between the two groups was due to the influx of aerosol particles with a long residence time by long-distance transport from China and local weather conditions (e.g., RH).

• Asian Journal of Atmospheric Environment
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• v.7 no.2
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• pp.65-71
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• 2013

Japanese cedar (Cryptomeria japonica) pollinosis is the most popular pollinosis in Japan. It has been reported that Cryptomeria japonica pollen allergenic species are suspended as fine particles in the urban atmosphere. These allergenic fine particles are responsible for inducing asthma by breaking into the lower respiratory tract. It has also been found that pollinosis symptoms on the sufferers appear mainly at night-time by the results from epidemiological studies. However, the exact reason for these phenomena is not yet clarified. In this study, the diurnal and nocturnal behaviours of Cryptomeria japonica pollen grains and their allergenic species in the urban area of Saitama city of Kanto Plain were investigated. Airborne pollen grains and allergenic Cry j 1 concentrations in total suspended particulate matter (TSP) were investigated at two sampling sites, a heavy traffic road (roadside site) and at the balcony of the $10^{th}$ floor of the Building of Research and Project of Saitama University (general urban site). The latter sampling site where located about 300 m away from the roadside site was used as a general urban site unaffected by automobile traffic. The airborne pollen counts were measured with a real-time pollen monitor. Cry j 1 particles were collected with two high volume air samplers, and these concentrations were measured by surface plasmon resonance method with a Biacore J system. The diurnal variation of the airborne pollen counts was similar to the trends of temperature and wind speed during the day-time; whereas its tendency with wind speed trend was not observed during the night-time. Airborne pollen counts were lower with northern wind than with southern wind because the pollen comes from the mountainous areas, and the mountains in the south are closer, about half the distance to the northern mountains. It is suggested that the peaks of airborne pollen counts during night-time in the sampling site occurred by transport of pollen grains released during day-time in the mountainous forest areas, located c.a. 100 km away from the sampling site. On the roadside site the allergenic Cry j 1 concentrations were higher than at the general urban site, nevertheless pollen grains counts were lower. These results suggested that worsening of pollinosis symptoms during night-time in urban area was caused by transport of pollen grains during day-time in the mountainous forest areas. Moreover, pollen allergenic species become different morphology from pollen grain at roadside site, and the subsequent pollen grains re-suspension by automobile traffic.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.6
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• pp.823-832
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• 2004

Atmospheric aerosol particles collected in Seoul on four single days, each in every seasons of 2001, were characterized and classified on the basis of their chemical species using low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA). Low-Z particle EPMA technique can analyze both the size and the chemical species of individual aerosol particles of micrometer size and provide detailed information on the size distribution of each chemical species. The major chemical species observed in Seoul aerosol were aluminosilicate, silicon dioxide, calcium carbonate, organic, carbon-rich, marine originated, and ammonium sulfate particles, etc. The soil originated species, such as aluminosilicate, silicon dioxide, and calcium carbonate were the most popular in the coarse fraction, meanwhile, carbonaceous and ammonium sulfate were the dominant species found in the fine fraction. Marine originated species such as sodium nitrate was frequently encountered, up to 30% of the analyzed aerosol particles.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.6
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• pp.583-592
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• 2017

A method is proposed for locating the heat sources from temperature observations, and its applicability is investigated for urban thermal environment simulations. A Lagrangian particle dispersion model, which is originally built for simulating the pollutants spread in the air, is exploited to identify the heat sources by transporting the Lagrangian heat particles backwards in time. The urban wind fields are estimated using a diagnostic meteorological model incorporating the morphological model for the urban canopy. The proposed method is tested for the horizontally homogeneous urban boundary layer problems. The effects of the turbulence levels and the computational time on the simulation are investigated.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.1
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• pp.1-7
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• 1997

Anion concentrations and distributions of airborne fine particles less than 2 $\mu$m in urban atmosphere were determined from Feb. 5 to 16, 1996. The sampling was carried out using 8 stages Hering's low pressure impactor (LPI, aerodynamic cutoff diameters are 0.05, 0.075, 0.11, 0.26, 0.50, 1.0, 2.0, and 4.0$\mu$m) on the top of a five-story building located at Kon-Kuk university in Seoul. Average concentrations if C $l^{[-10]}$ , N $O_3$$^{[-10]}$ and S $O_4$$^{2-}$ were 9.4, 8.4, and 14.5 $\mu\textrm{g}$/㎥, respectively. The distributions of these anion concentrations were bimodal types which showed two peaks in the range of 0.075~0.12 ${\mu}{\textrm}{m}$ and 0.5~1 ${\mu}{\textrm}{m}$ in aerodynamic diameter. These results were 2.5~4.7 times higher than anion concentrations collected by Anderson low volume air sampler.

• Journal of the Korean institute of surface engineering
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• v.57 no.2
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• pp.98-104
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• 2024

In order to overcome the urban heat island effect, highly functional paint is attracting attention as a promising means by shielding heat on the structure (building) surface. When a paint was prepared containing nano-sized silica particles, the heat-insulating performance was relatively higher than that of paints with other sizes. In addition, developed paints showed enhanced properties such as chemical resistance and abrasion resistance test because of the presence of nano-sized silica included in functional paint.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.597-604
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• 2003

In the soil washing process, the contaminants are usually removed by abrasion from soil particles using mechanical energy and water However, organic contaminants with low water solubility like polycyclic aromatic hydrocarbons (PAH) are remained on soil particles. Previous studies have shown that surfactant possessing amphipathic activity enhances the solubility of organic materials. For this reason solutions with surfactants have been used to improve removal of organic contaminants on soil washing process. But, in this manner, many problems were found like complete loss of surfactants and additional contamination by surfactant. The remediation method using microemulsion has been introduced to overcome these disadvantages. In this case, surfactants are recycled by phase separation of microemulsion after remediation. In microemulsion process, the surfactant will be recycled by phase separation of the microemulsion into a surfactant-rich aqueous phase and an oil phase after extraction. That is why remediation concept applying microemulsion as washing media has been Introduced. Suitable microemulsion have to be used in order to have the chance of refilling the soil after decontamination and to avoid any risk due to toxicity. The purpose of this research is to evaluate effect of microemulsion to remediation of contaminated soil. We performed test with various organic contaminants like Pyrene and BTEX, also compared efficiency of remediation in microemulsion process with soil washing

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.863-868
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• 2004

The use of oyster shells is proposed as a substitute construction material for geotechnical applications. To investigate recycling possibility as a substitute of sand compaction pile (SCP) for oyster shells, the geotechnical characteristics including permeability and shear strength of crushed oyster shell, sand and crushed oyster shell-sand mixted soil. Experimental results show that the crushed oyster shells are lighter than sand in weight, and have similar characteristics on permeability to sand. The results of direct shear test show that the measured value of friction angle ${\Phi}$ of crushed oyster shell was lager than that of sand. It would be expected that more angular particles (crushed oyster shells) would interlock more thoroughly than rounded particles (send).