• Fire Science and Engineering
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• v.32 no.1
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• pp.99-107
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• 2018

Diesel cars employ a diesel particulate filter (DPF) to reduce the discharge of fine dust. However, cases of fires caused by DPFs have been reported in diesel cars. In this study, I examined the regulation of exhaust gas and exhaust gas recirculation in diesel cars. Then, I analyzed cases of car fires caused by DPFs, their characteristics, car fire factors related to DPFs and preventive measures, and their consideration in investigations of the causes of fires. Finally, regarding car fire investigations, this study proposed a process of proving that fires are caused by DPFs.

• Journal of Korea Foundry Society
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• v.37 no.4
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• pp.115-122
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• 2017

The aim of this research is to evaluate the wear properties of (TiB+TiC) paticulate reinforced titanium matrix composites (TMCs) by in-situ synthesis. Different particle sizes (1500, $150{\mu}m$) and contents (0.94, 1.88 and 3.76 mass% for Ti, 1.98 and 3.96 mass% for the Ti6Al4V alloy) of boron carbide were added to pure titanium and to a Ti6Al4V alloy matrix during vacuum induction melting to provide 5, 10 and 20 vol.% (TiB+TiC) particulate reinforcement amounts. The wear behavior of the (TiB+TiC) particulate reinforced TMCs is described in detail with regard to the coefficient of friction, the hardness, and the degree of reinforcement fragmentation during sliding wear. The worn surfaces of each sliding wear condition are shown for the three types of wear studied here: transfer layer wear, particle cohesion wear and the development of abrasive areas. The fine reinforcements of TMCs were easily fragmented from the Ti matrix as compared to coarse reinforcements, and fragmented debris accelerated the decrease in the wear resistance.

• Safety and Health at Work
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• v.8 no.4
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• pp.407-409
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• 2017

Air pollutants of concern include traffic-related air pollution, including particulate matter in respirable coarse and fine size fractions. There are no critical studies to date into associations between knowledge, awareness, and attitudes in using proper respiratory masks and prevalence of respiratory symptoms among urban street vendors in Thailand. In this study, we estimated adverse respiratory health outcomes among street vendors, in particular young adults, in Bangkok, Thailand, using a self-report questionnaire. Street vendors, who were not currently smoking and not having known diagnosed respiratory diseases, were recruited. They were selected from selected roadsides at Chong Nonsi, Bangkok. Participants (n = 30) reported having lower respiratory (50%), upper respiratory (37%), and other symptoms (70%). Also, 53% of participants had never used respiratory personal protective equipment (PPE: masks). Among those using PPE, all used masks not proper for particulate matter. Results suggested knowledge, awareness, and attitudes concerning proper PPE use needs to be increased among street vendors in Bangkok, Thailand.

• Journal of People, Plants, and Environment
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• v.23 no.1
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• pp.15-21
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• 2020

In this study, we compared efficiency of different aquatic plants in removing indoor pollutants and examined their potential to purify indoor air. Two liter of water in chamber was used as the control, while the other chambers containing water lettuce (Pistia stratiotes), water hyacinth (Eichhornia crassipes), and water coin (Hydrocotyle umbellata) were used as treatment groups. Temperatures inside all the chambers were maintained between 20 ℃ and 23 ℃. Humidity in the chambers with aquatic plants increased by 30% and 50% control respectively. The removal of formaldehyde per unit leaf area was examined in each aquatic plant. It turned out that water hyacinth removed the highest amount of formaldehyde, followed by water lettuce and water coin. Both water hyacinth and water lettuce increased the amount of removal of formaldehyde until the end of the experiment. In the case of airborne dust (PM 10) and fine dust (PM 2.5), water coin, which had the highest number of leaves, removed more PM 10 and PM 2.5 than the other aquatic plants, with statistically significant difference. In addition, both water coin and water hyacinth smoothly opened and closed stomata before and after the experiment. Consequently, as the aquatic plants were effective in controlling humidity and removing pollutants, they can be used as air purifying plants.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.2
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• pp.108-121
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• 2009

The suspended particulate matters have been collected on membrane filters and glass fiber filters by an 8-stage cascade impactor for 2 years (Sep. 2005${\sim}$Sep. 2007) in Kyung Hee University-Global Campus located on the border of Yongin and Suwon. The 20 chemical species (Al, Mn, Si, Fe, Cu, Pb, Cr, Ni, V, Cd, Ba, $Na^+$, ${NH_4}^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, ${NO_3}^-$, and ${SO_4}^{2-}$) were analyzed by an ICP-AES and an IC after performing proper pre-treatments of each sample filter. Based on these chemical information, the PMF receptor model was applied to identify the source of ambient size-by-size particulate matters. The receptor modeling is the one of the statistical methods to achieve resonable air pollution management strategies. A total of 10 sources was identified in 9 size-ranges such as long-range transport, secondary aerosol, $NH_{4}NO_{3}$ related source, coal combustion, sea-salt, soil, oil combustion, auto emission, incineration, and biomass burning. Especially, the secondary aerosol source assorted in fine and coarse modes was intensively studied.

• Asian Journal of Atmospheric Environment
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• v.6 no.2
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• pp.96-103
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• 2012

Ambient particulate matter (PM) and particle-bound polycyclic aromatic hydrocarbon (PAH) concentrations were measured continuously for 70 days at a Korean elementary school located near a highway. The $PM_{10}$, $PM_{2.5}$, and $PM_1$ values were measured with a light-scattering, multi-channel, aerosol spectrometer (Grimm, Model 1.107). The number concentrations of the particles were measured using a scanning mobility particle sizer and counter (SMPS+C) which counted particles from 11.1 to 1083.3 nm classified in 44 channels. Particle-bound PAHs were measured with a direct reading, photoelectric aerosol sensor. The daily $NO_2$, $SO_2$, and CO concentrations were obtained from a national air-monitoring station located near the school. The average concentrations of $PM_{10}$, $PM_{2.5}$, and $PM_1$ were 75.3, 59.3, and $52.1{\mu}g/m^3$, respectively. The average number concentration of the ultrafine particles (UFPs) was $46,307/cm^3$, and the averaged particle-bound PAHs concentration was $17.9ng/cm^3$ during the study period. The ambient UFP variation was strongly associated with traffic intensity, particularly peak concentrations during the traffic rush hours. Particles <100 nm corresponded to traffic-related pollutants, including PAHs. Additional longterm monitoring of ambient UFPs and high-resolution traffic measurements should be carried out in future studies. In addition, transient variations in the ambient particle concentration should be taken into consideration in epidemiology studies in order to examine the short-term health effects of urban UFPs.

• Environmental Analysis Health and Toxicology
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• v.20 no.4 s.51
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• pp.365-374
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• 2005

Ambient air particulate matters are classified into two distinct modes in sire distribution, namely the coarse and fine particles. Correlation between high particulate concentration and adverse effect on human populations has long been recognized. However, the toxicology of these adverse efforts has not been clarified. We investigated the genotoxic effect of PM 2.5 collected from urban area in Seoul by comet assay (A549 cells), CBMN assay (CHO-K1 cells) and EROD-microbioassay (H4IIE cells). Results from in vitro micronucleus assay and comet assay showed that PM 2.5 samples collected from traffic area, residential area and indoor air induced chromosomal damage and DNA breakage in a non-cytotoxic dose. The complex mixture effect of these PM 2.5 extracts was quantified by EROD-microbioassay in terms of its bio-TEQ (biologiral -TCDD equivalent concentration) which was 70.87$\pm$28.07, 93.55$\pm$21.80 and 14.31 $\pm$ 1.10 ng/g-PM 2.5 in traffic area, residental area and indoor air samples, respectively. Conclusively, we suggested that PM 2.5 collected from traffic area and residential area contains CYPIA inducer and genotoxic materials.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.1
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• pp.46-56
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• 2009

The main purpose of this study was to investigate air quality trends of ambient aerosol with obtaining size-fractionated information. The suspended particulate matters were continuously collected on membrane filters and glass fiber filters by an 8-stage cascade impactor for 2 years (Sep. 2005 $\sim$ Sep. 2007) in Kyung Hee University-Global Campus. 8 ionic species ($Na^+$, ${NH_4}^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, ${NO_3}^-$, and ${SO_4}^{2-}$) were analyzed by an IC after performing proper pretreatments of each sample filter. The average concentration levels of each ion were $9.24{\mu}g/m^3$ of ${SO_4}^{2-}$, $7.35{\mu}g/m^3$ of ${NO_3}^-$, $2.81{\mu}g/m^3$ of ${NH_4}^+$, $2.11{\mu}g/m^3$ of $Ca^{2+}$, $1.65{\mu}g/m^3$ of $Cl^-$, $1.87{\mu}g/m^3$ of $Na^+$, $0.80{\mu}g/m^3$ of $Mg^{2+}$, and $0.54{\mu}g/m^3$ of $K^+$, respectively. The distribution pattern of $Na^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, and ${NO_3}^-$ was bi-modal and two peaks appeared in the range of $0.4{\sim}0.7{\mu}m$ and $3.3{\sim}4.7{\mu}m$, respectively. On the other hand, ${SO_4}^{2-}$, ${NH_4}^+$, and $K^+$ showed patterns of uni-modal distribution, mostly abounded in the fine mode group.

• Journal of Environmental Health Sciences
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• v.36 no.4
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• pp.306-312
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• 2010

This field study was performed to evaluate the efficiency of a plasma ion-operated air cleaner in temporal reduction of airborne pollutants emitted from a pig housing facility. In the case of gaseous pollutants, the plasma ion air cleaner was not effective in reducing levels of ammonia, hydrogen sulfide, nitrogen dioxide, or sulfur dioxide (p>0.05). In the case of particulate pollutants, however, the air cleaner was effective in reducing levels of particulate matter ($PM_{2.5}$ and $PM_1$) by 79(${\pm}6.1$) and 78(${\pm}3.0$)%, respectively. Unlike the case of these fine particle fractions, the reduction of total suspended particles (TSP) and $PM_{10}$ following treatment was almost negligible. In the case of biological pollutants, the mean reduction efficiencies for airborne bacteria and fungi were relatively low at 22(${\pm}6.6$) and 25(${\pm}8.7$)%, respectively. Taken together, these results indicate that in terms of air pollutants released from this pig housing facility, the plasma ion air cleaner was primarily effective in reducing levels of $PM_{2.5}$ and $PM_1$.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.157-167
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• 2017

Millions of People die every year from diseases caused by exposure to outdoor air pollution. Especially, one of the most severe types of air pollution is fine particulate matter (PM10, PM2.5). South Korea also has been suffered from severe PM. This paper analyzes regional risks induced by PM10 and PM2.5 that have affected domestic area of Korea during 2014~2016.3Q. We investigated daily maxima of PM10 and PM2.5 data observed on 284 stations in South Korea, and found extremely high outlier. We employed extreme value distributions to fit the PM10 and PM2.5 data, but a single distribution did not fit the data well. For theses reasons, we implemented extreme mixture models such as the generalized Pareto distribution(GPD) with the normal, the gamma, the Weibull and the log-normal, respectively. Next, we divided the whole area into 16 regions and analyzed characteristics of PM risks by developing the FN-curves. Finally, we estimated 1-month, 1-quater, half year, 1-year and 3-years period return levels, respectively. The severity rankings of PM10 and PM2.5 concentration turned out to be different from region to region. The capital area revealed the worst PM risk in all seasons. The reason for high PM risk even in the yellow dust free season (Jun. ~ Sep.) can be inferred from the concentration of factories in this area. Gwangju showed the highest return level of PM2.5, even if the return level of PM10 was relatively low. This phenomenon implies that we should investigate chemical mechanisms for making PM2.5 in the vicinity of Gwangju area. On the other hand, Gyeongbuk and Ulsan exposed relatively high PM10 risk and low PM2.5 risk. This indicates that the management policy of PM risk in the west side should be different from that in the east side. The results of this research may provide insights for managing regional risks induced by PM10 and PM2.5 in South Korea.