• Analytical Science and Technology
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• v.35 no.5
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• pp.212-217
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• 2022

In this study, ozone (O₃) samples were prepared for investigating the heterogeneous reactions between O₃ and tropospheric aerosols and were characterized by spectroscopic methods. O₃ generated from an ozone generator was purified by selective adsorption on refrigerated silica gel, followed by transfer to a sample bulb. The amount of UV light (λ = 256 nm) absorbed by O₃ was measured as a function of time at two different temperatures (room temperature and 50 ℃) and under different irradiation conditions. A correlation plot of 1/[O₃] versus time showed that O₃ decomposition follows the 2^nd order reaction rate under a steady-state approximation. The initial concentration of O₃, observed rate constants (k_obs), and the half-life of O₃ in the sample stored at room temperature were determined to be 2.74 [±0.14] × 10¹⁶ molecules·cm^-3, 4.47 [±0.64] × 10^-23 molecules^-1·cm³·s^-1, and 9.5 [±1.4] days, respectively. The evaluation of O₃ stability under various conditions indicated that special care should be taken to prevent the exposure of the O₃ samples to hightemperature environment and/or UV radiation. This study established a protocol for the preparation of highly purified O₃ samples and confirmed that the O₃ samples can be stored for a day after preparation for further experiments.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.513-518
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• 2003

Recently, advanced systems for water treatment are introduced for water quality improvement. One of those systems is water treatment method using ozone($O_3$). For it has strong oxidizing energy, it is necessary to have materisl stability against $O_3$. In this paper, epoxy resin specimens using as anticorrosive material of concrete structure for drink water are used to serve as a material of deterioration evaluation. It is to be studied weight loss, surface corrosion of specimens, ingredient analysis of floating particle, a solute of chemical ingredient by way of accelerated ozone testing. As the results of experiment, specimen weight is decreased. The surface of specimen is eroded heavily and showed a loss of gloss and floating particle, and in the stability for drinking water, harmful ingredient is not detected in the water.

• The Korean Journal of Ecology
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• v.23 no.1
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• pp.39-43
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• 2000

Carbon dioxide (CO₂) and ozone (O₃) fluxes were measured over Glycine max canopy using the bowen ratio energy balance method at Fuchu - 20 km west of Tokyo, in late July and late September 1996. The CO₂, and O₃, fluxes were influenced by variation in leaf area index (LAI) during the measuring period. When LAI was more than 3.0, the CO₂ flux was found to be positively correlated with photosynthetically active radiation (PAR). The O₃, flux was always positive with an average deposition velocity for this case of about 0.5 mol m/sup -2/s/sup -1/. A positive correlation existed between the deposition velocity of O₃ and CO₂ during the period of LAI＞2.0.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1052-1057
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• 2005

Recently, the ozone treatment of wasting activated sludge has become one of the effective and feasible process for the sludge reduction. The objective of this study is to investigate the availability of ozonized wasting sludge on external carbon sources 13r phosphorus release. Experiment results showed that the ozone treatment of activated sludge could produce a large amount of VFA such as acetic acid and isobutyric acid. For example, 50.24 mg/L acetic acid was produced with the ozone dose of 0.05 g $O_3/g$ SS, and 123.56 mg/L acetic acid with 0.5 g $O_3/g$ SS. The higher ozone dose was applied, the more VFA was produced from sludge reduction into a limited point. Finally, using ozonated sludge as only carbon source, the batch experiment, to measure phosphorus release rate in anaerobic condition were performed. The specific phosphorus release rates were investigated as 0.94, 1.37, 1.48, 1.68 mg P/g VSS/hr with ozone dose of 0.05, 0.1, 0.2, 0.5 g $O_3/g$ SS, respectively. Considering the degree of mineralization, VFA production, phosphorus release rate, and economical aspect, the optimal ozone dose for sludge reduction and using carbon sources ranged from 0.05 to 0.1 g $O_3/g$ SS.

• Journal of the Korean Electrochemical Society
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• v.11 no.3
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• pp.135-140
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• 2008

An electrochemical generation of ozonized water was investigated by using ${\beta}-PbO_2$ as an anode and tap water as an anolyte. According to the potentiometric ozone detection which utilizes potential differences arisen from a chemical reaction of ozone and iodide, increasing tendency of ozone concentration on electrolysis time could be observed to show the maximum value of 8 ppm at an electrolysis time of 10 min. Ozone could be generated promptly even at an electrolysis time of 10 sec., suggesting great advantages of this electrochemical process in terms of simplicity and readiness that might be applied directly to practical uses including medical and/ or food industries. Influences of electrolysis on the properties and surface conditions of a $PbO_2$ electrode were also discussed from the results of cyclic voltammetry, scanning electron microscope, and X-ray diffractometer.

• Journal of Korean Society of Forest Science
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• v.96 no.5
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• pp.551-560
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• 2007

We investigated physiological damages and biochemical alleviation of five species of genus Acer under ozone fumigation in order to assess their tolerant ability against ozone toxicity. At the end of 150 ppb $O_3$ fumigation, photosynthetic characteristics were measured, and chlorophyll contents, malondialdehyde (MDA) and antioxidative enzyme activities were analyzed in the leaves of five maple trees (Acer buergerianum, A. ginnala, A. mono, A. palmatum, and A. palmatum var. sanguineum). The reduction of chlorophyll (chl) a in ozone-exposed plants was 16.8% (A. buergerianum) to 26.7% (A. ginnala) of control plants. For the content of chi b, A. ginnala and A. palmatum var. sanguineum represented the high reduction of 26.3% and 23.6%, respectively. The highest reduction on the chi a:b ratio was observed in the leaves of A. palmatum. The reduction of net photosynthesis in five species varied from 2.4% to 37.6%. Among five species, A. ginnala showed remarkable reduction (37.6%) for net photosynthesis in comparison with control. Carboxylation efficiency differed significantly (P < 0.05) among species and between control and ozone treatment. The reduction of carboxylation efficiency was the highest in the leaves of A. ginnala (44.7%). A. palmatum var. sanguineum showed the highest increase (41.7%) for MDA content. The highest increase of superoxide dismutase (SOD) activity represented in A. palmatum (26.1%) and the increase of ascorbate peroxidase (APX) activity ranged from 16.5% (A. ginnala) to 49.1% (A. palmatum var. sanguineum). A. mono showed the highest increase (376.6%) of glutathione reductase (GR) activity under ozone fumigation and A. buergerianum also represented high increase (42.3%) of GR activity. Catalse (CAT) activity increased in the leaves of A. ginnala, A. palmatun and A. palmatum var. sanguineum under ozone exposure, whereas A. buergerianum and A. mono decreased in comparison with control plants. In conclusion, physiological markers such as chlorophyll content and photosynthesis that responded sensitively to $O_3$ in maple trees were considered as the very important indicators in order to evaluate the tolerance against $O_3$ stress, and parameters were closely related with each other. Among anti oxidative enzymes, SOD and APX might be contributed to alleviate to $O_3$ toxicity through the increase of activity in all maple trees. Therefore, these compounds can be used as a biochemical maker to assess the stress tolerance to $O_3$.

• Asian Journal of Atmospheric Environment
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• v.5 no.2
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• pp.65-78
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• 2011

Ozone ($O_3$) is a main component of photochemical oxidants, and a phytotoxic anthropogenic air pollutant. In North America and Europe, the current concentration of $O_3$ has been shown to have significant adverse effects on vegetation. In this review, we summarize the experimental studies on the effects of $O_3$ on the growth and photosynthetic activity of Japanese forest tree species to understand the present knowledge and provide sound basis for future research toward the assessment of $O_3$ impacts on Japanese forest ecosystem. Since the 1990s, several Japanese researchers have conducted the experimental studies on the effects of ambient levels of $O_3$ on growth and physiological functions such as net photosynthesis of Japanese forest tree species. Although the sensitivity to $O_3$ of whole-plant growth is quite different among the species, it was suggested that the current ambient levels of $O_3$ in Japan are high enough to adversely affect growth and photosynthetic activity of Japanese forest tree species classified into high $O_3$ sensitivity group such as Japanese beech. The N load to soil has been shown to reduce the sensitivity to $O_3$ of Japanese larch and increase that of Japanese beech. To establish the critical level of $O_3$ for protecting Japanese forest tree species, therefore, it is necessary to take into account the N deposition from the atmosphere. There is little information on the combined effects of $O_3$ and other environmental factors such as elevated $CO_2$ and drought on growth and physiological functions of Japanese forest tree species. Therefore, it is necessary to promote the experimental study and accumulate the information on the combined effects of $O_3$ and any other abiotic environmental factors on Japanese forest tree species.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.2
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• pp.59-67
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• 2000

In this paper, an ozonizer, which can supply individual and superposed silent discharge using three-phase voltage has been designed and manufactured. The ozonizer consists of 3 electrodes(Central Electrode, Internal Electrode and External Electrode and External electrode) and 2 gaps (gap between Central Electrode and Internal Electrode, gap between Internal Electrode and External Electrode). Ozone is generated according to voltage supplying method to each electrode by individual silent discharge and three-phase superposed discharge. The characteristics of ozone generation were investigated with variation of discharge power and the flow rate of supplied gas (O2). In case of individual silent discharge, the maximum values of ozone concentration, ozone generation and ozone yield were obtained between internal electrode and external electrode, and its values were 2300[ppm], 570[mg/h] and 745[g/kWh] respectively. Each maximum value was 5039[ppm], 1773[mg/h] and 851[g/kWh] respectively, when three-phase superposed silent discharge was employed. Therefore, characteristics of ozone generation with three-phase voltage are improved compared with single-phase voltage because silent discharge is generated continuously.

• Journal of Environmental Science International
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• v.32 no.9
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• pp.613-626
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• 2023

This study investigates the impact of increased adoption of eco-friendly vehicles on ozone (O₃) concentrations in South Korea, utilizing the community multiscale air quality (CMAQ) model. In the summer of 2017 (June-August), we conducted two experiments: a BASE experiment, representing baseline emissions, and an R_30 experiment, involving a 30% emission reduction due to eco-friendly vehicles. The contrast between these experiments reveals that, while most air pollutants decreased with reduced vehicle emissions, O₃ concentrations surprisingly increased (up to 2.1 parts per billion) across South Korea. A further examination of O₃ concentration changes was conducted by analyzing daytime and nighttime variations as well as wind direction. During the daytime, O₃ concentrations notably rose near metropolitan areas due to reduced O₃ titration (O₃ + NO → O₂ + NO₂) resulting from emission reductions. At nighttime, O₃ concentrations exhibited a greater increase, attributed to the transport of daytime-generated O₃ to rural regions. Notably, the impact of reduced emissions in metropolitan areas on O₃ concentrations in downwind areas varied depending on the prevailing wind direction. These findings highlight that the promotion of eco-friendly vehicles, though effective in lowering certain air pollutants, might not directly influence O₃ concentrations. This study underscores the need to comprehensively understand the complicated chemistry of O₃ to develop effective strategies for air quality management.

• Journal of Environmental Science International
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• v.14 no.3
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• pp.327-333
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• 2005

The performance of ozone contactor in ozone-BAC advanced water treatment process was evaluated by the degree of decomposition of organic matters. The degree was measured by the analyses of $UV_{254}$ absorbance and the concentrations of DOC and BDOC for the sand filtered water and the ozone treated water, respectively. In addition, the ozone concentration in the contactor, required for the maximum BDOC concentration, was selected as the optimum concentration, and the appropriate residential time of ozone treated water in a reservoir was recommended based on the residual ozone concentration in the treated water. The following results were obtained from the pilot scale experiments. By ozonation $UV_{254}$ absorbance was decreased, and BDOC concentration was increased. The change of DOC concentration by ozonation was negligible, but the excess input of ozone resulted in the removal of the small amount of BDOC by complete oxidation. The optimum ozone concentration was 0.58mg $O_3/mg$ DOC. In order to remove residual ozone, 20minutes of the residential time were enough after ozonation.