• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1107-1108
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• 2006

As expanding municipal and industrial areas since started the economic development plan in earnest in 1970's, the water resource, mainly river surface water has been seriously polluted. Nevertheless, being upgraded in their treatment technologies for the drinking water, the safety has been issued one of crucially social problem in Korea. The water authorities has tried to improve the quality such as amending the drinking water quality standard to be monitored; hazardous chemicals and microorganis have been added and now 55 items, before 47 items, since in 2002. The Water Authorities of Seoul, the capital city of Korea, planned to assess the safty of drinking water quality after amended the standard. This study was conducted to assess the risk due to polluted chemicals including 21 heavy metals, VOCs, pesticides, PAHs, DBPs and organic chemicals among the regulated items. The risk assessment were undertaken hazard identification, exposure assessment, dose-response assessment and risk characterization. For the exposoure assessment, tap water, bottled water and purified water were sampled and analyzed in February, 2004. Risk characterization of detected chemicals was categorized into carcinogenecity and noncarcinogenecity, and estimated the excess of carcinogens and compapared with the reference dose (RfD) of noncarcinogenns. The excess risk of carcinogens from samples were considered comparatively in the acceptable levels; $10^{-6}$ for cancer risk and hazard quotient (HQ) 1.0 for noncancer risk. The deteced levels were estimated in $10^{-5}{\sim}10^{-6}$ of cancer risk and below 1.0 of HQ of noncancer risk. While three kinds of water were determined within the acceptal levels, DBPs were detected in tap water and purified were and some undesireable chemicals such as more fluoride detected rather than the quality stanadard. For the drinking water safety, it shoud be continuously monitored, assessed and managed as well risk communiction between the authoritis and public.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.E4
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• pp.163-168
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• 2001

Estimating the emission rate of VOCs from a gasoline industry at national level can be a challenging take even though the estimation is mean-based. However, using the procedures in the US EPA AP-42 guidelines, it is possible to approximate the mean industry emission rate once enough data are available. However, this estimate can be misled in the sense that there exist many stochastic factors in the EPA\\`s estimation procedures and also throughout the marketing channels of gasoline industry. Addressing the stochasticity problem in EPA\\`s procedure is hard to tackle because the detailed data needed to execute the estimation are not usually available even from refiners. Instead, this research tries to stay focused on the second type of stochasticity issue, raised from the mean0based metrological and marketing practice data collected from the 4 major refiners. To do so emission raters from each marketing channels (8 marketing points by 3 transportation types and by storage facilities of 4 refiners) are estimated monthly, following AP-42 procedures and using Tank 4.0. Once these estimates are acquired, the distribution of VOC emission rate for each marketing channel of all 4 refiners is estimated through simulation method using @Risk. The mean-based emission rates are weighted by company quantities to estimate the emission rate from the whole gasoline industry. Simple economic implication is provided, based on the result. This study found that, on the mean-bases, about 0.66% of gasoline marketed are evaporated into air. Considering the stochasticity in the estimation, about 90% of simulation results fell into the range of 0.65 to 0.68%. For 90% chance, the estimated economic loss is $54.65 million to $57.17 million, not counting the cost caused by air quality degradation and associated health impact.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.2
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• pp.150-160
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• 2014

Greenhouse gas (GHG) and Air Pollution (AP) emission inventories have been constructed and estimated independently up-to-date in Seoul. It causes difficulty in GHG and AP integrated management due to a difference in emission inventories. In this study, we constructed GHG and AP integrated emission inventories for direct and indirect sources in Seoul during the year 2010 in Energy activities for estimating GHG and AP emissions were derived from IPCC guideline, guidelines for local government greenhouse inventories, air pollutants calculation manual, and Indirect Emission Factors (IEF) reported by Korea Power Exchange. The annual GHG emission was estimated as 50,530,566 $tonCO_{2eq}$, of which 54.8% resulted from direct sources and the remaining 45.2% from indirect sources. Among direct sources, transportation sector emitted the largest GHG, accounting for 47.3% of the total emission from direct sources. As with indirect sources, purchased electricity sector only emitted 98.6% of the total emission from indirect sources. The annual AP emission was estimated as 283,701 tonAP, of which 85.9% was contributed by the combined AP emissions of transportation and fugitive sectors. Estimation of individual air pollutant showed that the largest source were transportation sector for CO, $NO_x$, TSP, $PM_{10}$ and NH3, non-energy sector for $SO_x$, and fugitive sector for VOCs. This study found some limitations in estimating GHG and AP integrated emissions, such as nonconforming emission inventories between GHG and AP, and no indirect AP emission factor of purchased electricity, and so on. Those should be further studied and improved for more effective GHG and AP integrated management.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.272-280
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• 2014

Objectives: The purpose of this study was to evaluate the characteristics of worker exposure to hazardous chemical substances and propose the direction of work environment management for protecting worker's health in the semiconductor assembly process. Methods: Four assembly lines at two semiconductor manufacturing companies were selected for this study. We investigated the types of chemicals that were used and generated during the assembly process, and evaluated the workers' exposure levels to hazardous chemicals such as benzene and formaldehyde and the current work environment management in the semiconductor assembly process. Results: Most of the chemicals used at the assembly process are complex mixtures with high molecular weight such as adhesives and epoxy molding compounds(EMCs). These complex mixtures are stable when they are used at room temperature. However workers can be exposed to volatile organic compounds(VOCs) such as benzene and formaldehyde when they are used at high temperature over $100^{\circ}C$. The concentration levels of benzene and formaldehyde in chip molding process were higher than other processes. The reason was that by-products were generated during the mold process due to thermal decomposition of EMC and machine cleaner at the process temperature($180^{\circ}C$). Conclusions: Most of the employees working at semiconductor assembly process are exposed directly or indirectly to various chemicals. Although the concentration levels are very lower than occupational exposure limits, workers can be exposed to carcinogens such as benzene and formaldehyde. Therefore, workers employed in the semiconductor assembly process should be informed of these exposure characteristics.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.141-147
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• 2000

Due to a rapid in automobiles since the 1980’s, the concentration of NO, and HC has also increased along with cases of VOCs. These air pollutants have created $O_3$ concentration, which cause a harmful effect to the human health. This issue has become a subject of great public interest. For this paper, to compare the concentration of $O_3$, NO, N $O_2$ between the rural and urban area in the winter, the concentrations of each have been measuredevery hour during Jan.~Feb. 2000, 1998, respectively. To calculate the Photochemical Steady State, $\Phi$= $J_{N O_2}$[N $O_2$]/ $k_1$[NO][ $O_3$], temperature and $J_{ N O_2}$ has been determined. The NO concentration in the rural are showed at below 10 ppb while the NO concentration in the urban area showed maximum value of 90~120 ppb. But the $O_3$ concentration in both areas showed less than 30 ppb. The reason is that the N $O_2$ photodissiciation rate is low due to the temperature being below 2$^{\circ}C$ and less than 60 degrees in the solar zenith angle during the winter time, which makes the $O_3$ concentration in both areas, similar in the concentration level. N $O_2$ photodissociation rate in both ares showed maximum value of 3.0mW/$\textrm{cm}^2$. Values of $\Phi$ determined from the rural area was consistently the unity, approaching 1. But values of $\Phi$ determined from the urban was roughly higher than unity, approaching above 1or 2 for clear sky-high sun(10:00~16:00).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.467-470
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• 2010

USN(Ubiquitous Sensor Network) is the network that widely applies for life of human being. It works out to sense, storage, process, deliver every kind of appliances and environmental information from the stucktags and sensors. And it is possible to utilize to measure and monitor about the place of environmental pollution which is difficult for human to install. It's studied constantly since it be able to compose easily more subminiature, low-power, low-cost than previous one. And also it spotlights an important field of study, graft the green IT and IT of which the environment and IT unite stragically onto the Network. This study realize a IAQM(Indoor Air Quality Management) sensing mechanism composition under the network and suggest the application of Environment monitoring system outlook to measure an Environment element.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.249-254
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• 2011

A nonthermal plasma reactor in conjunction with a tubular type with a ferroelectric (high-dielectric ceramic) pellet layer was designed and constructed. $SrBiTaO_9$ (SBT) pellets with 2.0 mm in diameter were held within the tube arrangement by two metal mesh electrodes (20 mm separation) connected to a high-voltage AC power supply. The dielectric constant of SBT pellets was 150 at room temperature and 500 at curie temperature ($335^{\circ}C$). The generation rate of ozone in the plasma reactor almost linearly increased with increasing applied voltage. In the case of the plasma reactor packed with SBT pellets the generation rate of ozone sharply increased at the applied voltage more than 20 kV. The ozone generation rate at the negative corona discharge was higher than that of the positive corona discharge. However, the destruction efficiency of toluene and methylene chloride was not increased in proportion to ozone concentration.

• Journal of Environmental Science International
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• v.32 no.5
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• pp.285-301
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• 2023

This study analyzed characteristics of ozone (O₃) formation regimes in Busan over a period of recent five years (2015~2019) and compared the findings with those obtained in Seoul. We employed four observed variations: early morning commuting-hour (i.e., 06:00-09:00 LST) nitrogen dioxide (NO₂), peak-hour (i.e., 12:00-16:00 LST) O₃, 8-hour average O₃ (MDA8 O₃), and △O₃ (=O_{3_max}- O_{3_min}) in Busan and Seoul. In addition, the NO₂-O₃ relation was assessed to interpret which of NOx-limited or volatile organic compound (VOC)-limited was dominant. In Busan, the annual mean O₃ concentration was relatively higher than in Seoul, whereas there were fewer high-concentration days. The Pearson correlation coefficients (R) between Early morning-hour NO₂ and the Peak-hour O₃ was positive (but close to zero) in Busan and negative in Seoul. Likewise, the R between the Early morning-hour NO₂ and the △O₃ showed a relatively considerable positive correlation (R=+0.4~0.5)(R=+0.4~0.5) in Busan, while a weak positive correlation (R=+0.1~0.2) in Seoul. From this result, it can be inferred that the O₃ formation regime in Busan was intrepreted to be nearly neutral or relatively closer to the NO_x-limited regime than Seoul, while Seoul to the VOC-limited regime. The study findings imply that O₃ control strategies should be applied differently in Busan and Seoul. The results here were inferred from surface NO₂ and O₃ observations, and the varification studies based on in-situ VOCs measurements would be needed.

• Analytical Science and Technology
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• v.19 no.6
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• pp.553-558
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• 2006

In this study, an attempt was made to measure uncertainties involved in the VOC analysis for the VOC working standards prepared by a dilution technique using Tedlar bags. For this purpose, VOC standard gases of benzene, toluene, xylene, and styrene were prepared at four different concentrations (4, 8, 20, and 40 ppb). These standard samples were then loaded on to the GC system equipped with air server/thermal desorption (AS/TD) system. Each of these four standard concentrations was analyzed individually to derive their respective calibration results. These calibration data sets were then compared across four different compounds. According to this comparison, differences in calibration patterns were moderately insignificant within the selected concentration range of 4~40 ppb. It was also observed that the loss of styrene standard was fairly high compared to other VOCs investigated simultaneously. The results of our study suggest that the analytical uncertainty associated with the preparation of VOC starndard gas using a dilution technique can be assessed in a fairly reasonable manner for samples with a narrow concentration range.

• Journal of Environmental Health Sciences
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• v.49 no.5
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• pp.275-288
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• 2023

Background: When basic local governments want to improve their air quality management policies, they need fundamental evidence, such as the effectiveness of current policies or scenario results. Objectives: The purpose of this study is to lay the groundwork for a process to calculate air pollutant reduction from basic local government air quality policies and provide numerical estimates of PM_2.5 concentrations following improved policies. Methods: We calculated the amount of air pollutant reduction that can be expected in the research region based on the Gyeonggi-do Air Environment Management Implementation Plan issued in 2021 and guidelines from the Korean Ministry of Environment. The PM_2.5 concentration variations were numerically simulated using the CMAQ (photochemical air quality model). Results: The research regions selected were Suwon, Ansan, Yongin, Pyeongtaek, and Hwaseong in consideration of population, air pollutant emissions, and geographical requirements. The expected reduction ratios in 2024 compared to 2018 are CO (3.0%), NO_x (7.9%), VOCs (0.7%), SO_x (0.1%), PM₁₀ (2.4%), PM_2.5 (6.1%), NH₃ (0.05%). The reduced PM_2.5 concentration ratio was highest in July and lowest in April. The expected concentration reduction of yearly mean PM_2.5 in the research region is 0.12 ㎍/m³ (0.6%). Conclusions: Gyeonggi-do is now able to quickly provide air pollutant emission reduction calculations by respective policy scenario and PM_2.5 simulation results, including for secondary aerosol particles. In order to provide more generalized results to basic local governments, it is necessary to conduct additional research by expanding the analysis tools and periods.