• Journal of Environmental Science International
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• v.14 no.6
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• pp.555-563
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• 2005

This study presents the characteristics of nocturnal inversion layer and their effect on the concentration variations of surface air pollutants using tethersonde and automatic weather station (AWS, 2 layer tower) system in Ulsan during 2003, The method for the distinction of inversion intensity was decided based on the sum of nocturnal temperature gradient. As the results, there was a close correlation (correlation coefficient of 0,76) between the maximum inversion height obtained from tethersonde and the sum of nocturnal temperature gradient. The air pollutant concentration was also directly proportional to the inversion intensity. When the inversion intensity was strong in the nighttime, ozone $(O_3)$ concentration was lower, while nitrogen dioxide $(NO_2)$ concentration was higher. The carbon monoxide (CO) concentration was gradually higher according to the nocturnal inversion intensity, whereas sulfur dioxide $(SO_2)$ concentration was relatively constant. In addition, we found that there was no correlation between the inversion intensity and TSP concentration.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.299-302
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• 2005

Vehicle occupant exposure to air pollutants has been a subject of concern in recent years because of higher levels of air pollutants inside gasoline or diesel-using vehicle, comparing to the surrounding atmosphere. This study evaluated the potential exposure to respirable suspended particulate (RSP), nitrogen dioxide ($NO_2$) and volatile organic compounds (VOCs), comparing weekday (Monday and Thursday) and weekend (Saturday). Indoor mean concentrations of RSP inside vehicle were 51.2 $ug/m^3$ and 75.52 $ug/m^3$ in weekday and weekend, respectively. Measured indoor NO$_2$ concentrations were 14,8 ppb and 20.8 ppb, respectively. Benzene and toluene mean concentrations inside vehicle were 5.4${\pm}$2.4 ppb and 23.8${\pm}$33.8 ppb, respectively.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.1
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• pp.44-53
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• 2006

This study purposed to investigate air pollution in car shipping yards and, for this purpose, we selected an outdoor open-air yard and an indoor ramp into the ship and measured the concentrations of sulfur dioxide, nitrogen dioxide, carbon monoxide, PM10, PM2.5 and heavy metals in the air. The results of this study are as follows. No significant difference was observed in temperature and humidity between the outdoor and indoor workshop, and the average air flow was 0.52 m/s in the indoor workshop, which is higher than 0.19 m/s in the outdoor workshop(p<0.01). The average concentrations of sulfur dioxide, nitrogen dioxide, carbon monoxide, PM10 and PM2.5 according to workplace were 0.03 ppm(${\pm}0.01$), 0.03 ppm(${\pm}0.01$), 0.46 ppm(${\pm}0.22$), $39.44{\mu}g/m^3$(${\pm}2.45$) and $5.45{\mu}g/m^3$(${\pm}1.15$) respectively in the outdoor workshop, and 0.15 ppm(${\pm}0.05$), 0.22 ppm(${\pm}0.06$), 8.85 ppm(${\pm}3.35$), $236.39{\mu}g/m^3$(${\pm}58.21$) and $152.43{\mu}g/m^3$(${\pm}35.42$) respectively in the indoor workshop. Thus, the concentrations of gaseous substances in the indoor workshop were 4.9-19.2 times higher than those in the outdoor workshop, and the concentrations of fine dusts were 5.9-27.9 times higher(p<0.01). In addition, according to the result of investigating pollutant concentrations according to displacement and the number of car loaded when shipping gasoline cars into the ship, no significant relation between the number of cars loaded and pollutants was observed in shipping passenger cars, but the concentrations of nitrogen dioxide and carbon monoxide got somewhat higher with the increase of the number of cars loaded(p<0.05). In addition, the concentrations of nitrogen dioxide, carbon monoxide, PM10 and PM2.5 in the air were significantly higher when shipping recreational vehicles, the displacement of which is larger than passenger cars, than when shipping passenger cars(p<0.01). On the other hand, the average heavy metal concentrations of the air in indoor workshop were: lead $-0.05{\mu}g/m^3$(${\pm}0.10$); chromium $-0.90{\mu}g/m^3$(${\pm}0.18$); zinc $-0.38{\mu}g/m^3$(${\pm}0.24$); copper $-0.18{\mu}g/m^3$(${\pm}0.22$); and manganese and cadmium not detected. In addition, the complaining rates of 'asthma,' a major symptom of chronic respiratory diseases, were 18.5% and 22.5% respectively in indoor workers and outdoor workers. Thus the rate was somewhat higher in indoor workers but the difference was not statistically significant. The complaining rates of 'chronic cough' and 'chronic phlegm' were very low and little different between indoor and outdoor workers. The results of this study show that the reason for the higher air pollution in indoor than in outdoor workshop is incomplete combustion of fuel due to sudden start and over-speed when cars are driven inside the ship. In order to prevent high air pollution, efficient management measures should be taken including the observance of the optimal speed, the improvement of old ships and the installation of efficient ventilation system.

• Journal of Environmental Health Sciences
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• v.45 no.2
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• pp.113-125
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• 2019

Objectives: Although the risk assessments for nitrogen dioxide ($NO_2$) and ozone ($O_3$) have been extensively studied, most of the existing risk assessments were limited mainly to indoor environments such as workplaces, schools, and multi-use facilities. Therefore, integrated risk assessment is needed to consider exposure in all microenvironments, including outdoors. The purpose of this study was to assess the differences in risk among sub-population groups according to time-activity patterns and reported concentrations, as well as the lifetime risk of Koreans. Methods: In this study, we estimated time-weighted average exposure concentrations of $NO_2$ and $O_3$ for preschool children, students, housewives, workers, and seniors using residential time and indoor concentrations (house, school or workplace, other), outdoors, and transport by meta-analysis method. The risk for $NO_2$ and $O_3$ were assessed by hazard quotient using reference concentrations 30 and 60 ppb, respectively. The risk assessments were conducted through 1,000,000 Monte-Carlo simulations for probabilistic analysis. Results: Preschool children, students, housewives, workers, and seniors spent 91.9, 86.0, 79.8, 82.2, and 77.3% of their day in a house, school, or workplace, respectively. The risk assessment for the lifetime of a housewife and a worker showed that 33.8 and 28.4% of hazard quotients of $NO_2$ exceed 1, respectively, and more than 99% of hazard quotient of $O_3$ were less than 1. Conclusions: The risk of $NO_2$ and $O_3$ by sub-population group and for the lifetime of housewives and workers were assessed. The risk for $NO_2$ was higher than for $O_3$ and showed a different risk by sub-population group. Both $NO_2$ and $O_3$ showed a higher risk for housewives than for workers. This study can be used as a basis for lifetime exposure and risk assessment for $NO_2$ and $O_3$.

• Fire Science and Engineering
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• v.30 no.2
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• pp.7-18
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• 2016

This study evaluated the toxicity of the burning gas from the synthetic wood products used in housings or warehouses. The combustion products of five materials, viz. impregnated laminated board, MDF, Douglas fir plywood, core plywood, and Lauan retardant, were analyzed using SEM, FTIR and a Cone Calorimeter. For the Lauan retardant, 256,965 ppm of carbon dioxide ($CO_2$) and 1,475 ppm of sulfur dioxide ($SO_2$) were measured, which are 2.5 times and 3.6 times as high as their lethal concentrations of 100,000 ppm and 400 ppm, respectively. For the impregnated laminated board, 1,569 ppm of nitrogen dioxide ($NO_2$) was measured, which is 6 times as high as its lethal concentration of 250 ppm. For MDF, 795 ppm of ammonia ($NH_3$) was measured, which is higher than its lethal concentration of 750 ppm. As a result, most internal-finishes generated toxic combustion products at levels higher than their lethal concentrations, which underlines the importance of the selection and manufacturing of internal-finish materials.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.160-169
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• 2000

Daily indoor and outdoor nitrogen dioxide ($NO_2$) concentration for 30 days were measured in 28 houses with questionnaire of housing characteristics in Brisbane, Australia. Using mass balance equation and regression analysis, penetration factors and source strength factors were calculated. The penetration factors of 27 houses except one house were between zero and 1, though penetration factor should be between zero and 1 by means of mass balance equation. Relationship between indoor and outdoor concentrations in each 27 house was calculated using regression analysis. According to the obtained linear regression equation, the slope means penetration factor and the intercept means source strength factor. Calculated mean and standard deviation of coefficients of determination ($R^2$) in electric and gas range houses were $0.70{\pm}0.13$ and $0.57{\pm}0.21$, respectively. The source strength factors were more than zero in 27 houses. Mean and standard deviation of slopes in electric and gas range houses were $0.65{\pm}0.18$ and $0.56{\pm}0.12$, respectively. Mean and standard deviation of intercepts in electric and gas range houses were $1.49{\pm}1.25$ and $5.77{\pm}3.55$, respectively. Air exchange rate and source strength were calculated from penetration factor and source strength factor, respectively. Geometric mean and standard deviation of calculated air exchange rates in 27 houses were $1.1/hr{\pm}1.5$. Presence of gas range was the most significant factor contributing to indoor $NO_2$ level in house characteristics (p=0.003). In gas range houses, source strengths ranged from 4.1 to $33.1cm^3/hr{\cdot}m^3$ with a mean $12.7cm^3/hr{\cdot}m^3$ and a standard deviation 9.8. The source strengths of gas range houses were significantly different from those of electric range houses by t-test (p<0.001)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.779-786
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• 2008

This study was performed to evaluate the characteristics of current air quality and to examine the monthly and yearly variation of $SO_2,\;O_3,\;CO,\;NO_2$, and fine particulate matter(PM-10) concentration in Seosan for the period of 1998-2006. During the recent 3 years, from 2004 to 2006, the yearly mean concentration of $SO_2,\;NO_2$, and PM-10 remained stability but CO and $O_3$ are gradually decreased. The monthly mean concentration of $NO_2$, CO, and $SO_2$ were high in the winter season and decreased steadily to the summer season, but the maximum concentration of $O_3$ and PM-10 appeared in the springtime. The number of days exceeding 24-hour standards for PM-10 were 54 times at Dokgodri and 25 times at Dongmundong. The number of sampling days exceeding the 1-hour and 8-hour standards for $O_3$ were 68 and 210 times at Dongmundong and at Dokgotri 93 and 213 times, respectively.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1293-1300
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• 2014

The temperature data influences on various policies of the country. In this article, the autoregressive error (ARE) model has been considered for analyzing the monthly and seasonal temperature data at the northern part of the Chungcheong Namdo, Seosan monitoring site in Korea. In the ARE model, five meteorological variables, four greenhouse gas variables and five pollution variables are used as the explanatory variables for the temperature data set. The five meteorological variables are wind speed, rainfall, radiation, amount of cloud, and relative humidity. The four greenhouse gas variables are carbon dioxide ($CO_2$), methane ($CH_4$), nitrous oxide ($N_2O$), and chlorofluorocarbon ($CFC_{11}$). And the five air pollution explanatory variables are particulate matter ($PM_{10}$), sulfur dioxide ($SO_2$), nitrogen dioxide ($NO_2$), ozone ($O_3$), and carbon monoxide (CO). The result showed that the monthly ARE model explained about 39-63% for describing the temperature. However, the ARE model will be expected better when we add the more explanatory variables in the model.

• Clean Technology
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• v.27 no.4
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• pp.367-371
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• 2021

The oxy-combustion system is one of the carbon recovery and storage technologies (CCS: Carbon capture & storage) that performs coal combustion using pure oxygen and recirculated flue gas. This is a technology that facilitates storage of carbon dioxide by generating an exhaust gas consisting of only carbon dioxide without a process of separating carbon dioxide and nitrogen when coal is burned using pure oxygen and recirculated flue gas mixture instead of a conventional air combustion system that produces carbon dioxide and nitrogen mixed exhaust gas. In this study, the characteristics of generated NO and SO₂ as atmospheric pollutants during oxy-combustion were examined using O₂/CO₂ mixed simulation gas. The reaction temperature was varied from 900 ℃ to 1200 ℃ and oxygen partial pressure was varied from 30% to 50%. The results showed that NO and SO₂ concentrations in flue gas increased as the oxygen concentration and the reaction temperature in the furnace increased. The partial pressure of CO₂ in flue gas also increased as the oxygen concentration and the reaction temperature in the furnace increased. As a results of comparing NO production of 30% O₂/CO₂ oxy-combustion with air combustion, NO in flue gas increased with reaction temperature in both experiments and NO of oxy-combustion was 40 ~ 80 ppm lower than that of air combustion.

• Journal of ILASS-Korea
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• v.14 no.2
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• pp.49-58
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• 2009

Non-edible vegetable oils instead of edible vegetable oils as a substitute for diesel fuel are getting a renewed attention because of global reduction of green house gases and concerns for long-term food and energy security. Out of various non-edible vegetable oils, karanja, mahua, linseed, rubber seed and cotton seed oils are selected in this study. A brief review of recent works related to the application of the above five vegetable oils and its derivatives in CI engines is presented. The production technologies of biodiesel based on non-edible vegetable oils are introduced. Problems in vegetable oil or biodiesel fuelled CI engine are included. In addition, future works related to spray characteristics of non-edible vegetable oil or biodiesel from it are discussed. The biodiesel fuel, irrespective of the feedstock used, results in a decrease in the emission of hydrocardon (HC), carbon monoxide (CO), particulate matter (PM) and sulphur dioxide ($SO_2$). It is also said to be carbon neutral as it contributes no net carbon dioxide to the atmosphere. Only oxides of nitrogen (NOx) are reported to increase which is due to oxygen content in the biodiesel fuel. The systematic assessment of spray char-acteristics of neat vegetable oils and its blends, neat biodiesel and its blends f3r use as diesel engine fuels is required.