• Journal of Environmental Health Sciences
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• v.36 no.2
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• pp.108-117
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• 2010

In this study, ambient particulate matter ($PM_{2.5}$ and $PM_{10}$) levels were measured and their chemical and physical properties were characterized. Two sites in Gwangju were sampled once a month from December 2008 to November 2009. The annual mean concentrations of $PM_{2.5}$ and $PM_{10}$ were $26.9\;{\mu}g/m^3$ and $46.3\;{\mu}g/m^3$, respectively, in Nongseongdong and $26.1\;{\mu}g/m^3$ and $44.8\;{\mu}g/m^3$, respectively, in Duam-dong. $PM_{2.5}$ levels were 1.8 times higher than the USA Environmental Protection Agency (EPA) national ambient air quality standard for $PM_{2.5}$ ($15\;{\mu}g/m^3$). The average $PM_{2.5}/PM_{10}$ ratio of 0.58 suggested that $PM_{2.5}$ is a significant component of the ambient particle pollution. The order of concentration of metallic elements in $PM_{2.5}$ and $PM_{10}$ was Si > Al > Fe > Zn > Pb > Cu > Mn. Cd was not detected. The earth crustal enrichment factors for Cr, Cu, Pb and Zn in $PM_{2.5}$ were higher than those in $PM_{10}$. When the earth crustal enrichment factors for Cr, Cu, Pb and Zn were higher than 10, this suggested influence from anthropogenic sources. The soil contribution ratios for $PM_{2.5}$ and $PM_{10}$ were 11.3% and 16.4%, respectively, and were higher in the fall and winter. Anions (${SO_4}^{-2}$, ${NO_3}^-$, and $Cl^-$) comprise 28.7% of $PM_{2.5}$ and 21.4% of $PM_{10}$. The correlation coefficient of Zn-Fe, Mn-Cu, Fe-Cu and Fe-Mn in $PM_{2.5}$ was high in the sampling sites, and metallic elements were primarily from anthropogenic sources such as fuel combustion and vehicle emissions.

• Journal of Biosystems Engineering
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• v.24 no.4
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• pp.351-358
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• 1999

In these days, we are faced to a couple of difficult problems, the one is the unstable price of the energy due to the shortage of fossil fuel resources and the other is the serious environmental pollution from the excessive consumption of fossil fuel. In order to save the thermal energy for the house heating, in this study the heat pump using the natural thermal energy resources was provided for Ondol heating and the thermal energy consumption of the heat was compared to that of oil boiler. The results could be summarized as follows: 1. In the Ondol room the temperature difference between the Ondol surface and room air was about 5∼$10^{\circ}C$ in accordance with the ambient temperature. 2. The Ondol room heating efficiency of the heat pump with compressor of 2PS was the highest at the water flow rate of 200 l/h. 3. The energy saving rate of the heat pump to the oil boiler for heating the Ondol system was 19.3%. 4. The Ondol heating cost of the heat pump was less 20.6% than that of oil boiler when oil price was 478 won/l.

• Asian Journal of Atmospheric Environment
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• v.9 no.4
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• pp.272-279
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• 2015

The information about the dispersion and scavenging of traffic-related pollutants at the locations near busy expressways is very helpful to highway planners for developing better plans to reduce exposures to air pollution for people living as well as children attending schools and child care centers near roadways. The objective of the current study was to give information in the dispersion and scavenging of vehicle-derived pollutants at the region near a busy urban expressway by a combination of two different model calculations. The modified Gaussian dispersion model and the Lagrange type below-cloud scavenging model were applied to evaluate $NO_x$ dispersion and DEP (Diesel exhaust particles) wet removal, respectively. The highest $NO_x$ was marked 53.17 ppb within 20-30 meters from the target urban expressway during the heaviest traffic hours (08:00AM-09:00AM) and it was 2.8 times higher than that of really measured at a nearby ambient measuring station. The calculated DEP concentration in size-resolved raindrops showed a continuous decreasing with increasing raindrop size. Especially, a noticeable decrease was found between 0.2 mm and 1.0 mm raindrop diameter.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.841-846
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• 2008

Recently the LNG(liquified natural gas) public buses have been introduced to prevent the air pollution in metropolitan areas. As the LNG temperature in fuel tank is as low as $-162^{\circ}C$. the thermal and structural effects of tank components need to be studied for safe introduction in the market. Especially the support system of LNG fuel tank in vehicle, which has connected with inside and outside of tanks, should put attention to reduce the structural stress due to cryogenic temperature and to restrict the heat flux from ambient. There are two supporting systems in the tank, that one is connected between inside and outside tanks by welding, and the other is the inserted support system which is a cylindrical SUS bar inserted in a hole of the supporting plate. In this study the temperature distribution and thermal stress of the inserted support system were evaluated by using the utility program as ANSYS. The results showed that the rate of heat transfer to inner tank through this support system was quite small due to limited contact of support bar with plate. but the thermal stress of support plate was obtained beyond the limited tensile value of SUS304. The cautious design for the support plate part, therefore, should be given to make the safe support system of LNG vehicle fuel tank.

• Advances in concrete construction
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• v.9 no.2
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• pp.139-147
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• 2020

This paper reports the effect of Rice Husk Ash (RHA) in geopolymer concrete on strength, durability and microstructural properties under ambient curing at a room temperature of 25℃ and 65±5% relative humidity. Rice husk was incinerated at 800℃ in a hot air oven. and ground in a ball mill to achieve the required fineness. RHA was partially added in 10, 15, 20, 25, 30 and 35 percentages to fly ash with 10% of GGBS to produce geopolymer concrete. Test results exhibit that the substitution of RHA in geopolymer concrete resulted in reduced strength properties during initial curing. In the initial stage, workability of GPC mixes was affected by RHA particles due to the presence of dormant particles in it. It is evident from the microstructural study that the presence of RHA particles densifies the matrix reducing porosity in concrete. This is due to the presence of RHA in geopolymer concrete, which affects the ratio of silica and alumina, resulting in polycondensation reactions products. This study suggests that incorporation of rice husk ash in geopolymer concrete is the solution for effective utilization of waste materials and prevention of environmental pollution due to the dumping of industrial waste and to produce eco-friendly concrete.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.6
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• pp.508-519
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• 2015

The objective of this study was to quantitatively estimate $PM_{2.5}$ source contribution in Gyeongsan. Ambient $PM_{2.5}$ samples have been collected on zefluor, quartz and nylasorb filter by $PM_{2.5}$ samplers of cyclone method from September 2010 to December 2012. Collected samples were analyzed for determining 17 inorganic elements, 8 ions, and 8 carbon components after pretreatment. Based on these chemical information, the PMF model was applied to estimate the quantitative contribution of air pollution sources. The results of the PMF modeling showed that the sources were apportioned by biomass burning source (15.5%), secondary sulfate source (16.0%), industry source (10.4%), soil source (7.0%), gasoline source (9.1%), incinerator source (10.4%), diesel emission source (11.0%), and secondary nitrate source (20.6%), respectively. To analyze local source impacts from various wind directions, the CPF analysis were performed using source contribution results with the wind direction values measured at the site.

• 대한예방의학회:학술대회논문집
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• 1997.10b
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• pp.237-239
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• 1997

• International conference on construction engineering and project management
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• 2024.07a
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• pp.238-241
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• 2024

With the development of living standard, people spend more time indoors, and the diversified home decoration will lead to indoor hazardous gas emission. Among them, formaldehyde (HCHO) is one of the most important sources of indoor air pollution, which is commonly found in building materials as a human carcinogen. To address this issue, we developed highly efficient multifunctional green building coatings (GBC) by TiO₂, enhancement silica fume (ESF) and spent fluid catalytic cracking catalysts (sFCCC). Among these prepared GBC, the GBC-0.8 exhibited HCHO removal efficiency of 85.0 % under visible light at ambient temperature, which was much higher than that of commercial coatings (30.8%). In addition, moisture adsorption-desorption carrier tests were executed by different humidity. The humidity control capacity of GBC-0.8 could reach 293.8 g/m² and demonstrate superior stability after 3 cycles. Compared with pristine TiO₂, the addition of ESF and sFCCC showed higher specific surface area and pore size distribution, which was beneficial to improve humidity control and photocatalytic degradation performance. This study provides a promising green method for designing multifunctional green building materials coatings to recycle waste into high-value products and remove HCHO at room temperature

• Particle and aerosol research
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• v.20 no.3
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• pp.79-94
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• 2024

Exposure to ambient particulate matter (PM) 2.5 can impair alveolar macrophages (AMs) functions and induce pathological conditions. This study explores the impact of PM2.5 exposure on AMs, focusing on gene expression changes and functional alterations. Murine AMs cell line MH-S were exposed to PM2.5 at a concentration of 100 ㎍/ml for durations of 3 and 48 hours. After 3 hours of exposure, genes involved in inflammatory and immune responses were activated, including TNF and B-cell receptor signaling pathways. In contrast, 48 hours of exposure significantly altered genes related to cell proliferation, apoptosis, and immune processes, with PI3K-Akt and cytokine-cytokine receptor interaction pathways. PM2.5 initially triggers immune responses; however, prolonged exposure over 48 hours impairs AM functions risk of chronic inflammation and cancer. This research provides foundational data for therapeutic approaches related to PM2.5 exposure.

• The Korean Journal of Ecology
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• v.16 no.4
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• pp.397-408
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• 1993

Gas exchange rates and concentrations of ascorbate and glutathlone were measured in needles of eastern white pine(Pinus strohltr) trees differing in foliar sensitivity to ambient oxidant pollution during a ten month period beginning in mid-June, 1988. Current-year needle dry mass and length was 60 to 75% and 45 to 60% less, respectively, in sens~tive trees than in a tolerant tree. Net photosynthesis ($P_n$) and needle conductance ($g_n$) were greatest in the tolerant individual through late September when the rates begin to decline In trees. Needle transpiration rates showed a trend similar to $P_n$ and $g_n$. Ascorbate and total glutathione concentrations in current-year needles increased through the summer and fall, reached a maximum in mid-winter, and then decreased in the spring. Consistently throughout the year, ascorbate concentration was highest in the tolerant tree until the initial springtime decline began in April. The difference In needle ascorbate between the tolerant and sensitive individuals was greater in the summer months (25 to 30%) than in the winter months (8 to 19%). Glutathione content was similar, as was the ratio or oxidized /reduced glutathione, in both tolerant and sensitive trees.