• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.656-665
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• 2004

An Ozone reaction model combined with CFD(Computational Fluid Dynamics) technique was developed in this research, in the simulation of ozonation, hydrodynamic behavior as well as reaction model is important because ozone is supplied to treated water as gas ozone. In order to evaluate hydrodynamic behavior in an ozone contactor, CFD technique was applied. CFD technique elucidated hydrodynamic behavior in the selected ozone contactor, which consisted of three main chambers. Three back-mixing zones were found in the contactor. The higher velocities of water were observed in the second and third compartments than that in the first compartment. The flow of the opposite direction to the main flow was observed near the water surface. Based on the results of CFD simulation, the ozone contactor was divided into small compartments. Mass balance equations were established were established in each compartment with reaction terms. This reaction model was intended to predict dissolved ozone concentration, especially. We concluded that the model could predict favorably the mass balance of ozone, namely absorption efficiency of gaseous ozone, dissolved ozone concentration and ozone consumption. After establishing the model, we discussed the effect of concentration of gaseous ozone at inlet, temperature and organic compounds on dissolved ozone concentration.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.503-514
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• 2004

In Seoul metropolitan area, nocturnal variation of surface ozone concentrations observed at 27 monitoring sites from 1998 to 2002 showed that high ozone levels occurred frequently during the spring. Frequency distributions for nighttime ozone indicated that elevated concentrations in spring were influenced by advection of different air mass compared to other seasons. Surface wind analysis during the spring revealed that relatively strong southwesterly winds were associated with nocturnal ozone enhancement, which can be attributed to the regional transport of ozone. In order to identify the origin of nocturnal ozone enhancement in spring, 3-day backward trajectories were calculated by HYSPLIT 4 for the episode days and then classified. The results showed that NW, W, and SW flows, indicating influence of polluted air masses from the China continent, have 51% in a]1 the episode days, which suggest that the nocturnal ozone enhancement can occur under the effect of long-range transport of ozone-laden air mass on a regional scale. Case study of nocturnal ozone maxima associated with long-range transport was discussed in more detail in the light of meteorological conditions. Southwesterly synoptic flow along the outer edge of moving high-pressure system was found to be the important cause of nocturnal ozone maxima in Seoul. This flow could lead to be long-range transport of ozone that had effectively accumulated in the stagnating portion of the system located eastern coast of China. Low atmosphere soundings, backward trajectories, and elevated ozone and CO levels at the back-ground tiles gave evidence for regional effects on nocturnal ozone enhancement In Seoul.

• Asian Journal of Atmospheric Environment
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• v.2 no.1
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• pp.47-53
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• 2008

In this study, we analyzed how ozone pollution could be differently measured and how these different measures varied year to year and across the ten most populated cities in the United States, from 1980 to 2000. Although peak values of ozone concentration have been significantly reduced in most polluted U.S. cities for the last 20 years, the annual average values of ozone concentration have not been lowered as much as peak values. Ozone concentration data for each city shows a unique pattern of distribution, central tendency, and also there is a wide variation among different ozone measures. Two different cities with the same annual mean concentration of ozone can experience very different distributions of ozone concentration within a year. Ozone measures also show a wide margin of variability as they are estimated from different ozone monitoring sites within each city. Ozone pollution statistics can be largely varied depending on the choice of measures, monitoring sites, and averaging time period. EPA's new ozone standard of 0.08 ppm averaged over an eight-hour appears to be more stringent than the current maximum ozone standard of 0.12 ppm averaged over one hour.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05d
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• pp.25-28
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• 2003

Ozone is a strong and useful oxidizing gas for the fabrication of oxide thin films. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper an ozone condensation system was evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone was condensed by an adsorption method and the ozone concentration reached 8.5 mol% in 2.5 h after the beginning of the ozone condensation process, indicating high effectiveness of the condensation process. Ozone was continuously desorbed from the silica gel by the negative pressure. We found the decomposition in the ozone concentration negligible if the condensed ozone is transferred from the ozone condensation system to the film growth chamber within a few minutes.

• Journal of the Korean Data and Information Science Society
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• v.22 no.1
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• pp.125-136
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• 2011

Ground-level ozone, an air pollutant that is monitored by the Environmental Protection Agency (EPA), damages human health by irritating the respiratory system, reducing lung function, damaging lung cells, and aggravating asthma and other chronic conditions. In March 2008, the EPA strengthened ozone standards by lowering acceptable limits from 84 parts per billion to 75 parts per billion. Here epidemiologic data is used to study the effects of ozone regulation on human health and assessed how various regulatory standards for ozone may affect nonaccidental mortality, including respiratory-related deaths during ozone season. The assessment uses statistical methods based on hierarchical Bayesian models to predict the potential effects of the different regulatory standards. It also analyzes the variability of the results and ho they are impacted by different modeling assumptions. We focused on the technical an statistical approach to assessing relationship between new ozone regulations and mortality while other researches have detailed the relationship between ozone and human mortality. We shows a statistical correlation between ozone regulations and mortality, with lower limits of acceptable ozone linked to a decrease in deaths, and projects that mortality is expected to decrease by reducing ozone regulatory standards.

• Transactions on Electrical and Electronic Materials
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• v.1 no.2
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• pp.18-22
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• 2000

An ozone condensation system is evaluated from the viewpoint of an ozone supplier fro oxide thin film growth. Ozone is condensed by the adsorption method and its concentration is analyzed using the thermal decomposition method, The concentration of ozone exceeds 90mol% and ozone is supplied for a sufficiently long time to grow oxide thin films. Investigation of the ozone decomposition rate demonstrates that ozone can be transferred into the film growth chamber without marked decomposition. The ozone concentration is also evaluated using a quardrupole mass analyzer and the accuracy of this method is compared with the results of the thermal decomposition method.

• Journal of Environmental Science International
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• v.20 no.11
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• pp.1465-1481
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• 2011

The accuracy of ozone sensitivity coefficients estimated with HDDM (High-order Decoupled Direct Method) can vary depending on the $NO_x$ (Nitrogen Oxides) and VOC (Volatile Organic Compound) conditions. In order to evaluate the applicability of HDDM over the Seoul Metropolitan Area (SMA) during a high ozone episode in 2007 June, we compare BFM (Brute Force Method) and HDDM in terms of the $1^{st}$-order ozone sensitivity coefficient to explain ozone change in response to changes in NOx and VOC emissions, and the $2^{nd}$-order ozone sensitivity coefficient to represent nonlinear response of ozone to the emission changes. BFM and HDDM estimate comparable ozone sensitivity coefficients, exhibiting similar spatial and temporal variations over the SMAduring the episode. NME (Normalized Mean Error) between BFM and HDDM for the episode average $1^{st}$- and $2^{nd}$-order ozone sensitivity coefficients to NOx and VOC emissions are less than 3% and 9%, respectively. For the daily comparison, NME for the $1^{st}$- and $2^{nd}$-order ozone sensitivity coefficients are less than 4% ($R^2$ > 0.96) and 15% ($R^2$ > 0.90), respectively. Under the emission conditions used in this study, two methods show negative episode average $1^{st}$-order ozone sensitivity coefficient to $NO_x$ emissions over the core SMA. The $2^{nd}$-order ozone sensitivity coefficient to $NO_x$ emissions leads ozone to respond muchnonlinear to the reduction in $NO_x$ emissions over Seoul. Nonlinear ozone response to reduction in VOC emissions is mitigated due to the $2^{nd}$-order ozone sensitivity coefficient which is much smaller than the $1^{st}$-order ozone sensitivity coefficient to the emissions in the magnitude.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.3
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• pp.345-360
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• 2004

The late sea-breeze and its impacts on ozone distributions were investigated during April to September from 1998 to 2002, in the Busan metropolitan area (including surrounding areas) using the surface ozone concentrations (obtained at 9 monitoring sites), local meteorological variables (obtained near the shore), together with synoptic data. The urban scale ozone concentration was also simulated using the MM5/UAM-V to better understand the role of late sea-breeze in Busan. The results from observation study showed that most of the late sea-breeze occurred when weak offshore synoptic flow (northwesterly) suppressed development of sea - breeze, and the ozone concentration level and frequencies exceeding ozone standard increased with the onset time of sea breeze. We also found that the late sea-breeze clearly induces relatively weak wind speed and high temperature during the daytime As a result it enhances the photochemical ozone accumulation and delays the occurrence time of the averaged maximum ozone concentrations. The results of simulation for high ozone episode (24 August, 2001) by MM5/UAM -V revealed that the late sea-breeze interacted with weak offshore synoptic wind can contribute significantly to high ozone concentration in the coastal urban area. The simulated horizontal and vertical distribution of ozone concentration indicated that ozone can be accumulated over the sea under stagnant condition and return to the land in the late afternoon with the sea breeze, suggesting both the relationship between late sea-breeze and recirculation and the importance of late sea -breeze effects influencing severe ozone pollution in Busan.

• Journal of Environmental Impact Assessment
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• v.8 no.2
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• pp.21-29
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• 1999

This study was conducted to investigate the characteristics of surface ozone concentration and occurrence of high ozone concentration using hourly ozone and meteorological data of 1997~1998 in Pusan coastal area. Monthly mean ozone concentration was highest in Spring(35.4ppb) and lowest in Winter(22.2ppb). Relative standard deviation indicating clearness of observation site was 0.42 that is similar to urban area. The diurnal variation of ozone concentration of Dongsamdong showed maximum at 15~16LST and minimum 07~08LST that typical pattern of ozone concentration. In ozone episode period(May 18~23, 1998), diurnal change of ozone concentration was very high, and ozone concentration was related to meteorological parameters such as temperature, relative humidity, wind speed, cloud amount and radiation on a horizontal surface.

• Journal of Environmental Science International
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• v.16 no.8
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• pp.985-994
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• 2007

To investigate the effect of NOx and VOCs(volatile organic compounds) on the generation of high ozone episode, examined the hourly variations of ozone, NOx and VOCs concentrations, and calculated the ozone isopleth about maximum ozone concentrations using OZIPR which was presented by U. S. EPA at three sites in Busan. There was some difference by the sites, but decreasing VOCs concentration was effective for reduction of ozone at 22 July, the episode day of 2005. In the year 2006, the episode day was 8 August and the variations of NOx and VOCs concentration was little than variation of ozone. So it was estimated that the photochemical production of ozone was low than transportation of ozone. And the result of the OZIPR modeling was that decreasing VOCs concentration was effective for reduction of ozone.