• Journal of Korean Society for Atmospheric Environment
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• v.27 no.5
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• pp.614-622
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• 2011

In this study, a new tunnel ventilation method with a high velocity air curtain flow has been investigated for improving the ventilation exhaust efficiency and removing air pollutants in subway tunnels. At upper or lower position right downstream of a main duct connected with a ventilation opening, air curtain flows were suppled into the main duct where the air flow velocity was in the range of 2~6 m/s. Exhaust efficiency was monitored for both cases with and without air curtain flow for different air velocities, locations and injection angles of the air curtain. Particulate matter concentrations (PM10, PM2.5 and PM1.0) were also checked at both the main duct and ventilation opening before and after supplying air curtain flows. Lower air velocity of the main duct flow, higher air velocity of the air curtain led to higher exhaust efficiency and the air curtain condition of 30..inclined injection toward the main flow showed the maximum exhaust efficiency. The exhaust efficiency of about 24% without the air curtain could be improved to about 34% after using the air curtain flow. PM concentration decreased at the main duct and increased at the ventilation opening after using the air curtain flow. Therefore, the suggested method to use air curtain flows in tunnels will be probably one of the promising tools to reduce air pollutants in subway tunnels.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.84-91
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• 2008

Due to increasing need for better emission characteristics and lower fuel consumption rate in automotive engines, alternative fuels are drawing more attentions recently. The GTL (gas to liquid) is the one of most favored candidates. In this study, emission characteristics are compared between diesel and GTL fuel in commercial 2.0 liter diesel engine and vehicle with CRDi(Common Rail Direct injection) system. The effects of injection timings on emission and fuel consumption rate are compared at various engine speeds and loads. Noticeable reduction in HC, CO and PM emissions are observed due to higher cetane number and low sulfur and aromatic contents in GTL. On the trade-off curve of NOx and PM(Particulate matter) GTL showed much more benefits than diesel, where about 30% of PM mass decreased at the same operating conditions. On CVS 75 mode test in vehicle, GTL showed an excellent emission enhancement, in which 50% of HC, 21% of PM, and 12% of NOx engine-out emissions are decreased compared to ULSD(Ultra low sulfur diesel) fuel.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.27-31
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• 2007

The number of vehicles employing diesel engines is rapidly rising. Accompanying this trend, application of an after-treatment system is strictly required as a result of reinforced exhaust regulations. The Diesel Particulate Filter (DPF) system is considered as the most efficient method to reduce particulate matter (PM), but the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Therefore, the present study evaluates the effect of fuel injection characteristics on regeneration performance in a DOC and a catalyzed CR-DPF system. The temperature distribution on the rear surface of the DOC and the exhaust gas emission were analyzed in accordance with fuel injection strategies and engine operating conditions. A temperature increase more than BPT of DPF system was obtained with a small amount fuel injection although the exhaust gas temperature was low and flow rate was high. This increase of temperature at the DPF inlet cause PM to oxidize completely by oxygen. In the case of multi-step injection, the abrupt temperature changes of DOC inlet didn't occur and THC slip also could not be observed. However, in the case of pulse type injection, the abrupt injection of much fuel results in the decrease of DOC inlet temperatures and the instantaneous slip of THC was observed.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.46 no.4
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• pp.319-327
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• 2020

Particulate matters (PM) are small particulate pollution that decrease the function of skin barrier, which causes inflammatory skin diseases and extrinsic aging. In this study, we evaluated the effect of preventing the adherence of PMs from several cosmetic products applied to human skin using iron oxide black. The PM floating chamber consists of skin exposure area, PM inlet, floating power device, and an outlet so that PM can be naturally attached to the skin while floating in the chamber. The change in skin brightness according to the floating concentration of alternative fine dust was checked to confirm the optimal floating concentration conditions. The intensity difference (before-after intensity, Δ) before and after adhesion of iron oxide black was proportional to the amount of PM adhered. The anti-adherence effect of iron oxide black on five cosmetic products were evaluated through 20 each subjects by comparing the amount of iron oxide black adhered on the control and treatment. The difference in brightness before and after the iron oxide black attached to the skin was calculated and compared with the control group(p < 0.05). When over 150 mg of iron oxide black was adhered on the skin, the interference of intensity was low and clearly showed the skin adhered pattern. According to the application of the five cosmetics, the intensity difference was significantly lower than the control group. This means that depending on the product, it prevented the attachment of iron oxide black. This study is a safe and useful method to confirm the prevention of PM skin adherence. In conclusion, cosmetics can prevent the adherence of PM on the skin according to the formulation or ingredients characteristics.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.1
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• pp.69-76
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• 2004

Asian Dust samples were collected in the ambient air of Seosan, Western Korea, in spring of 2000∼2002. PM (Particulate Matter) concentrations were 199,8$\mu\textrm{g}$/㎥ in the first Asian Dust period (March, 23∼24) and 249.4$\mu\textrm{g}$/㎥ in the second period (April, 7∼9) of 2000. Compared with the concentrations in 2000, relatively low PM concentrations, 157.3$\mu\textrm{g}$/㎥ were measured in the periods of 2001 (April, 24∼26). Especially high PM concentration 953.1$\mu\textrm{g}$/㎥ were measured in the periods of 2002 (March, 21∼22). The variation in the PM concentration was observed according to the time for the formation of Asian dust. Considering the particle size distributions of Asian dust, a high concentration was also observed in coarse particle region. The results of backward trajectory model showed the route of the dust storms from northern area of Mongol and Gobi desert. Various mycelia grown from fungal spores were observed on the PM samples and identified at the genus level. All the genera from the three years (2000∼2002), Fusarium, Aspergillus, Penicillium, Basipetospora, Epicoccum and Monotospora are hyphomycetes in the division Fungi imperfecti (Deuteromycota). Fungal composition on the dust sample in March, 2000 was similar to the result of March, 2002. However, the result of April, 2001 was obviously different from the other dust periods. The variations of fungal compositions between the dust periods could be caused by the trajectories of the dust storms.

• Environmental Engineering Research
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• v.11 no.1
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• pp.33-44
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• 2006

The objective of this study was to develop and assess a method for estimating the rain scavenging ratios (RSRs) of particle-bound PAHs and PCBs using measured scavenging ratio of particulate matters (PM) and routinely available data of physico-chemical properties of PM. Paired atmospheric and rainwater sampling was conducted for a total of 4 rain events. Assuming equilibrium partitioning in rainwater-gas-PM system, an equation was derived for estimating the RSR of particle-bound chemicals as a function of RSR of PM and three equilibrium partition constants (i.e. dimensionless Henry's law constant, gas-particle partition coefficient, and water-particle partition coefficient). For all PAHs, the model significantly under-predicted the RSR while the model prediction for PCBs agreed with observation mostly within a factor of 5. The RSR model for the chemicals is of limited use as its accuracy critically depends on how close the observed partitioning of the chemicals in the gas-PM-rainwater system is to that estimated under the equilibrium assumption.

• Environmental Analysis Health and Toxicology
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• v.19 no.1
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• pp.109-117
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• 2004

The purpose of the present study was to examine the effect of diesel exhaust particles on human aortic vascular smooth muscle cells (VSMCs). DNA synthesis, cell viability and morphology of VSMCs after treatment of diesel exhaust particles (DEP) and fine particulate matter (PM$_{2.5}$) were assayed. PM$_{2.5}$ inhibited the DNA synthesis of VSMCs in a concentration -dependent manner, whereat DEP did not affect VSMCs up to 50$\mu\textrm{g}$/mL. These results were confirmed by morphological examination of VSMCs. PM$_{2.5}$ showed a dose-dependent cytotoxicity of VSMCs by MTT assay. Fraction 4 (organic acids) and fraction 8 (moderately polar compounds) showed the most potent inhibition of DNA synthesis of VSMCs, and fraction 7 (slightly polar compounds), fraction 9 (higher polar compounds), and fraction 6 (aromatic compounds) were next order. These results were confirmed by morphological examination of VSMCs. These results suggest that PM$_{2.5}$ inhibits the DNA synthesis of VSMCs through the cytotoxicity.oxicity.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.183-188
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• 2007

Recently, diesel engine has been frequently applied to RV, SUV and light duty truck due to the good fuel economy and high thermal efficiency. $NO_x$ and PM, environmental pollution materials are basically produced in diesel combustion process. The most important target in diesel engine research is the development of system to reduce the emissions of $NO_x$ and PM. Cooled EGR system is an effective method for the reduction of $NO_x$ emission and PM emission from a diesel engine and EGR cooler is the key component of the system. This study investigates the EGR cooler of oval gas tubes compared with the EGR cooler of shell & tubes to verify the heat exchange efficiency of cooler by means of engine dynamometer tests, rig performance tests and numerical analyses.

• Journal of environmental and Sanitary engineering
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• v.18 no.2
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• pp.67-74
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• 2003

In 15 schools where were chosen each location (East, West, South, North, Central) of Seoul area, 9 items were measured such as thermo circumstance(temperature, relative humidity, air current, intensity of illumination) particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide being based on the school indoor environment standard. It was showed that indoor temperature, relative humidity and air movement were suitable in comparison with school indoor environment standard. Intensity of illumination was suitable in comparison with all schools, only exception 2 schools. In all investigated schools were adequate for carbon monoxide, sulfur dioxide and nitrogen dioxide, in which each indoor environment standard (10ppw, 0.25ppm/hr, 0.15ppm/hr), but in 5 schools the carbon dioxide were exceeded for standard limit 1,000ppm of Korea. Indoor concentration of dust(PM-10) induced from respiration dust the standard of Korea ($150{\mu}g/m^3$) at all schools.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.229-230
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• 2003

최근에 대기오염이 심각해지면서 입자상 물질(particulate matter)의 농도가 증가하고 있으며, 이로 인해 대기의 시정뿐만 아니라 건강상의 문제를 일으킬 수 있다는 보고가 늘어나고 있다. 또한 미세 입자는 화학적 조성에 의해 인체에 미치는 영향이 증가할 수 있다. 중량농도 및 무기이온의 농도는 대부분 겨울철에 높으며, 특히 음이온 중에서는 SO$_4$$^{2-}$ , NO$_3$$^{-}$이, 양이온 중에서는 NH$_4$$^{+}$ 이온이 중량농도 중 차지하는 비율이 높다. (중략)