• Journal of Environmental Science International
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• v.29 no.4
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• pp.403-413
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• 2020

The purpose of this study is to understand the formation of internal wind paths of open space and its effect on meteorological factors and the generation of negative air ions. Various types of internal wind paths of open space were formed. Subsequently, changes in meteorological factors in each type were measured and the generated negative air ions were analyzed. The four key findings of the study are summarized as follows. First, the average wind speed formed inside the open space was analyzed such that the difference in wind speed was dependent on the difference in the composition of the wind path. Second, the negative air ion generation was observed to have the same trend as the average wind speed difference. Third, changes to the meteorological factors were more evident depending on the difference in wind path formation patterns. Solar radiation was expected to be highly affected by the physical structure (direction) of the target site. The relative humidity was found to show large difference depending on the different wind path type; however, this difference was significantly reduced when converting to absolute humidity. Fourth, it was found that the wind path formation type of open space affects meteorological factors through path analysis, and the changed meteorological factors affect the amount of generated negative air ions. Two conclusions can be obtained based on these results. First, the changes in internal wind speed formation of open space directly reduced the amount of generated negative air ions. Second, the changes in wind speed affect meteorological factors as well as the amount of generated negative air ions.

• Asian Journal of Atmospheric Environment
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• v.12 no.3
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• pp.274-288
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• 2018

Quantitative data of 50 non-polar organic compounds constituting $PM_{2.5}$ were continuously collected and analyzed from June 2016 to October 2017 (approximately 17 months) at Ichihara, one of the largest industrial areas in Japan. Target non-polar organic compounds including 21 species of polycyclic aromatic hydrocarbons (PAHs), 24 species of n-alkanes and 5 species of phthalate esters(PAEs) were simultaneously measured by gas chromatography/mass spectrometry. Basically, the average concentrations of the total PAHs, n-alkanes and PAEs in each season remained nearly level, and seasonal variations were little throughout the study period. These results suggest that the emission sources, which are not influenced by the seasons, are the dominant inputs for the target organic compounds. Diagnostic ratios of PAHs, assessment of n-alkane homologue distributions, carbon preference index, and the contribution of wax n-alkanes from plants were used to estimate source apportionments. These results indicate that anthropogenic sources were the main contributor for most PAHs and n-alkanes throughout the study period. The concentrations of PAEs selected in this study were low because emission amounts of these chemicals were little within the source areas of the sampling site. To our knowledge, this study is the first attempt to simultaneously measure a high number of non-polar organic compounds in $PM_{2.5}$ collected from the ambient air of Japan, and the resultant data will provide valuable data and information for environmental researchers.

• Asian Journal of Atmospheric Environment
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• v.11 no.4
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• pp.322-329
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• 2017

Perturbation in ambient particulate matter ($PM_1$, $PM_{2.5}$, $PM_{10}$) and black carbon (BC) concentrations was studied during a firecracker bursting episode in Diwali (Festival of Lights) celebrations in Nagpur, India. Firecracker bursting resulted in greater escalation in fine particulates over coarse particulates while $PM_{2.5}$ was found to be dominated by $PM_1$ concentration. On the Diwali day, daily mean concentration of $PM_{2.5}$ and $PM_{10}$ exceeded Indian National Ambient Air Quality Standards by over 1.8 and 1.5 times, respectively, while daily mean BC concentration on the same day was almost two times higher than the previous day. The BC/$PM_1$ ratio reduced remarkably from about 0.26 recorded before fire-cracker bursting activity to about 0.09 during fire-cracker bursting on Diwali night in spite of simultaneous escalation in ambient BC concentration. Such aberration in BC/$PM_1$ was evidently a result of much higher escalation in $PM_1$ than BC in ambient air during firecracker bursting. The study highlighted strong perturbations in ambient $PM_1$, $PM_{2.5}$, $PM_{10}$ concentrations and BC/$PM_1$ during the firecracker bursting episode. Altered atmospheric BC/$PM_1$ ratios could serve as indicators of firecracker-polluted air and similar BC/$PM_1$ ratios in local and regional air masses might be used as diagnostic ratios for firecracker smoke.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.4
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• pp.342-350
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• 2017

We report mass concentration and size fraction of TPM, $PM_{10}$ and $PM_{2.5}$ according to Korea standard test method (ES 01301.1 and ES 01317.1) and ISO 23210 methods. Particulate matters were sampled in large stationary emission sources such as a coal power plant and B-C oil refinery. The Korea standard test method PM mass concentrations showed 3~3.5 times larger than the cascade impactor method. On the other hand, the size fraction results showed less than 5% difference (i.e. $PM_{2.5}/PM_{10}$) between two methods. Moreover, the correlation coefficient ($r^2$) is 0.84 between TPM results of the Korea standard test method and CleanSYS. These results suggested not only improvement of current test criteria in terms of technical and theoretical aspects. Further, additional measurements are required in various large stationary sources to compare current field data.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.2
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• pp.259-268
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• 2018

The $PM_{2.5}$ samples were collected for every 6th day during one year at a suburban site in the Namwonsi, Jeollanamdo, Republic of Korea. Samples were analyzed for elemental carbon (EC), organic carbon (OC), and water-soluble organic carbon (WSOC), and levoglucosan. Although the water-soluble fraction of fine particulate OC consistently showed over a year, levoglucosan fraction of WSOC varied considerably from month to month. In this study, non-biomass-burning WSOC ($WSOC_{NBB}$) and biomass-burning $WSOC_{BB}$ were calculated with measurements of organic source tracer, levoglucosan, to better understand the temporal distribution and sources of WSOC. Two methods of predicting the secondary organic carbon from the biomass-burning $WSOC_{BB}$ Method and the EC-tracer Method were compared. Poor correlations between SOC estimated between two methods suggested that the use of the EC tracer method to estimate SOC may be significantly flawed. Direct measurements of levoglucosan and WSOC can provide a reasonable estimate of secondary organic carbon concentrations.

• Asian Journal of Atmospheric Environment
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• v.12 no.2
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• pp.139-152
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• 2018

The urban model inter-comparison study (UMICS) was conducted in order to improve the performance of air quality models (AQMs) for simulating fine particulate matter ($PM_{2.5}$) in the Greater Tokyo Area of Japan. UMICS consists of three phases: the first phase focusing on elemental carbon (UMICS1), the second phase focusing on sulfate, nitrate and ammonium (UMICS2), and the third phase focusing on organic aerosol (OA) (UMICS 3). In UMICS2/3, all the participating AQMs were the Community Multiscale Air Quality modeling system (CMAQ) with different configurations, and they similarly overestimated $PM_{2.5}$ nitrate concentration and underestimated $PM_{2.5}$ OA concentration. Various sensitivity analyses on CMAQ configurations, emissions and boundary concentrations, and meteorological fields were conducted in order to seek pathways for improvement of $PM_{2.5}$ simulation. The sensitivity analyses revealed that $PM_{2.5}$ nitrate concentration was highly sensitive to emissions of ammonia ($NH_3$) and dry deposition of nitric acid ($HNO_3$) and $NH_3$, and $PM_{2.5}$ OA concentration was highly sensitive to emissions of condensable organic compounds (COC). It was found that $PM_{2.5}$ simulation was substantially improved by using modified monthly profile of $NH_3$ emissions, larger dry deposition velocities of $HNO_3$ and $NH_3$, and additionally estimated COC emissions. Moreover, variability in $PM_{2.5}$ simulation was estimated from the results of all the sensitivity analyses. The variabilities on CMAQ configurations, chemical inputs (emissions and boundary concentrations), and meteorological fields were 6.1-6.5, 9.7-10.9, and 10.3-12.3%, respectively.

• Journal of Environmental Health Sciences
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• v.44 no.4
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• pp.360-369
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• 2018

Objectives: Outdoor tobacco smoke can penetrate into the indoor environment through cracks in the building envelope. This study aimed to characterize the particle size distribution of infiltrated secondhand smoke (SHS) through the gap in a single glazed and a secondary glazed window according to pressure differences in a chamber. Methods: Two polyvinyl chloride sliding windows were evaluated for infiltration, one with a glazed window and the other with a secondary glazed window. Each window was mounted and sealed in a polycarbonate chamber. The air in the chamber was discharged to the outside to establish pressure differences in the chamber (${\Delta}P$). Outdoor smoking sources were simulated at a one-meter distance from the window side of the chamber. The particle size distribution of the infiltrated SHS was measured in the chamber using a portable aerosol spectrometer. The particle size distribution of SHS inside the chamber was normalized by the outdoor peak for fine particles. Results: The particle size distribution of SHS inside the chamber was similar regardless of window type and ${\Delta}P$. It peaked at $0.2-0.3{\mu}m$. Increases in particulate matter (PM) concentrations from SHS infiltration were higher with the glazed window than with the secondary glazed window. PM concentrations of less than $1{\mu}m$ increased as ${\Delta}P$ was increased inside the chamber. Conclusions: The majority of infiltrated SHS particles through window gap was $0.2-0.3{\mu}m$ in size. Outdoor SHS particles infiltrated more with a glazed window than with a secondary glazed window. Particle sizes of less than $1{\mu}m$ were associated with ${\Delta}P$. These findings can be a reference for further research on the measurement of infiltrated SHS in buildings.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1713-1721
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• 1994

Intermetallic-matrix composites(IMCs) have the potential of combing matrix properties of oxidation resistance and high temperature stability with reinforcement properties of high specific strength and modulus. One of the major limiting factors for successful applications of these composite at high temperatures is the formation of interfacial reactions between matrix and ceramic reinforcement during composite process and during service. The purpose of the present investigation is to develop a better understanding of the nature of creep fracture mechanisms in a $Ni_{3}Al$ composite reinforced with both $TiB_{2}$ and SiC particulates. Emphasis is placed in the roles of the products of the reactions in determining the creep lifetime of the composite. In the present study, creep rupture specimens were tested under constant ranging from 180 to 350 MPa in vacuum at $760^{\cric}C$. The experimental data reveal that the stress exponent for power law creep for the composite is 3.5, a value close to that for unreinforced $Ni_{3}Al$. The microstructural observations reveal that most of the cavities lie on the grain boundaries of the $Ni_{3}Al$ matrix as opposed to the large $TiB_{2}/Ni_{3}Al$ interfaces, suggesting that cavities nucleate at fine carbides that lie in the $Ni_{3}Al$ grain boundaries as a result of the decomposition of the $SiC_{p}$. This observation accounts for the longer rupture times for the monolicthic $Ni_{3}Al$ as compared to those for the $Ni_{3}Al/SiC_{p}/TiB_{2} IMC$. Finally, it is suggested that creep deformation in matrix appears to dominate the rupture process for monolithic $Ni_{3}Al$, whereas growth and coalescence of cavities appears to dominate the rupture process for the composite.

• Biomedical Science Letters
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• v.26 no.3
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• pp.157-163
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• 2020

Long-term exposure to environmental pollutants can impair the human skin's barrier function and promote skin aging mechanisms. The visible consequences of these effects are dryness, wrinkles, black spots and worsening skin sensitivity. As awareness of the effects of environmental stressors on the skin has recently increased, consumers' demand for cosmetics that can provide anti-pollution effects is increasing. In this study, the possibility of anti-pollution cosmetic material was investigated by measuring the inhibitory effect of free radicals using a mixture of Nypa fruticans Wurmb (NF), Saussurea neoserrata (SN), Codium fragile (CF) and Enteromorpha compressa (EC), which has anti-inflammatory and antioxidant effects against irritation caused by dust. Combining the experimental results of a mixture of NF, SN, CF and EC by induction of fine dust stimulation, inhibition of inflammatory factors (PGE₂) and intracellular free radicals (ROS) by inhibiting effects were significant, indicating the possibility of use as anti-pollution cosmetics. The most plants used as sources of anti-pollution cosmetic ingredients contain antioxidants as active substances. In our highly industrialized and chemically polluted world, it is not surprising that most plants used as sources of anti-pollution cosmetic ingredients contain antioxidants as active substances. Considering our results, it can be suggested that this anti-pollutant consisting of NF, SN, CF and EC may be a good ingredient for skincare products for the cosmetic industry due to their antioxidant properties, which may especially alter skin aging.

• 한국해양학회지
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• v.28 no.4
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• pp.272-280
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• 1993

The seasonal variations of water salinity and the concentration of suspended particulate matter (SPM value) have been monitored in the Keum Estuary and its adjacent coastal area. the concentrations of suspended matters show great seasonal variations with low concentrations during summer season and high concentrations during winter season. During the flood season of summer, water salinities are less than 5% in the Keum estuary, and the brackish water (salinity<28%) prevails seaward covering the entire coastal area. The concentrations decreased abruptly to the seaward from higher than 100mg/l in the Keum estuary to less than 5 mg/l in the offshore. These phenomena probably results from the rapid e\deposition of riverine suspended matters within the Keum Estuary. The seasonal variations of suspended matter concentrations in the Keum Estuary and its adjacent coastal area are interpreted as the cyclic (seasonal) sedimentation processes in the west coast of Korea, that is, replenishment and deposition of fine sediments in summer, and resuspension and seaward transport in winter.