• Asian Journal of Atmospheric Environment
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• v.12 no.1
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• pp.1-16
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• 2018

Ground-level ozone ($O_3$) can be a menace for vegetation, especially in Asia where $O_3$ levels have been dramatically increased over the past decades. To ensure food security and maintain forest ecosystem services, such as nutrient cycling, carbon sequestration and functional diversity of soil biota, in the over-populated Asia, environmental standards are needed. To set proper standards, dose-response relationships should be established from which critical levels are derived. The predictor of the response in the dose-response relationship is an $O_3$ metric that indicates the dose level to which the plant has been exposed. This study aimed to review the relevant scientific literature and summarize the $O_3$ metrics used worldwide to provide insights for Asia. A variety of $O_3$ metrics have been used, for which we discuss their strengths and weaknesses. The most widely used metrics are based only on $O_3$ levels. Such metrics have been adopted by several regulatory agencies in the global. However, they are biologically irrelevant because they ignore the plant physiological capacity. Adopting AOT40 ($O_3$ mixing ratios Accumulated Over the Threshold of $40nmol\;mol^{-1}$) as the default index for setting critical levels in Asia would be a poor policy with severe consequences at national and Pan-Asian level. Asian studies should focus on flux-based $O_3$ metrics to provide relevant bases for developing proper standards. However, given the technical requirements in calculating flux-based $O_3$ metrics, which can be an important limitation in developing countries, no-threshold cumulative exposure indices like AOT0 should always accompany flux-based indices.

• Asian Journal of Atmospheric Environment
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• v.9 no.2
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• pp.173-186
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• 2015

In Bangladesh, increases in the tropospheric ozone ($O_3$) concentration and in soil salinization may lead to crop damage. To clarify the effects of $O_3$ and/or soil salinity on Bangladeshi wheat cultivars, BAW1059 (salt-tolerant) and Shatabdi (salt-sensitive) were exposed to 70-day treatments with $O_3$ (charcoal-filtered air (CF), $1.0{\times}O_3$, and $1.5{\times}O_3$) and different levels of soil salinity (0, 4, and $8dS\;m^{-1}$). In both cultivars, the whole-plant dry mass and grain yield were significantly reduced by exposure to $O_3$. Increased soil salinity caused significant reductions in whole-plant growth and yield in Shatabdi, but the reductions were negligible in BAW1059. No significant interactions between $O_3$ and salinity were detected for growth, yield, and leaf gas exchange parameters in both cultivars. We concluded that the effects of $O_3$ are not ameliorated by soil salinity in two Bangladeshi wheat cultivars, regardless of their salinity tolerance.

• Journal of Environmental Health Sciences
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• v.44 no.6
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• pp.539-547
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• 2018

Objectives: Ozone ($O_3$) advisories are issued by provincial/prefectural and city governments in Korea and Japan when oxidant concentrations exceed the criteria of the related country. Advisories issued only after exposure to high $O_3$ concentrations cannot be considered ideal measures. Forecasts of $O_3$ would be more beneficial to citizens' health and daily life than real-time advisories. The present study was undertaken to present a simplified forecasting model that can predict surface $O_3$ concentrations for the afternoon of the day of the forecast. Methods: For the construction of a simple and practical model, a multivariate regression model was applied. The monitored data on gases and climate variables from Japan's air quality networks that were recorded over nearly one year starting from April 2016 were applied as the subject for our model. Results: A well-known inverse correlation between $NO_2$ and $O_3$ was confirmed by the monitored data for Iksan, Korea and Fukuoka, Japan. Typical time fluctuations for $O_3$ and $NO_x$ were also found. Our model suggests that insolation is the most influential factor in determining the concentration of $O_3$. $CH_4$ also plays a major role in our model. It was possible to visually check for the fit of a theoretical distribution to the observed data by examining the probability-probability (P-P) scatter plot. The goodness of fit of the model in this study was also successfully validated through a comparison (r=0.8, p<0.05) of the measured and predicted $O_3$ concentrations. Conclusions: The advantage of our model is that it is capable of immediate forecasting of surface $O_3$ for the afternoon of the day from the routinely measured values of the precursor and meteorological parameters. Although a comparison to other approaches for $O_3$ forecasting was not carried out, the model suggested in this study would be very helpful for the citizens of Korea and Japan, especially during the $O_3$ season from May to June.

• 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.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.316-323
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• 1995

A vital step in magnetic tape manufacturing is the surface modification of polymer substrate prior to ink application. A critical element for good adhesion of magnetic ink on polymeric substrate is the ability to join ink in cost-effective manner. Corona discharging is one of the effective methods of modifying polymer surface to improve adhesion while maintaining the desirable properties of the film itself. Surface treatment by corona which is exposure of film surface to electron or ion bombardment, rather than mere exposure to active species, like atomic oxygen or ozone, can enhance adhesion by removing contaminant, electret, roughening surface, and/or introducing reactive chemical groups. Reactive neutrals, ions, electron and photons generated during the corona treatment interact simultaneously with polymers to alter surface chemical composition, wettability, and thus film adhesion. However, it is highly recommended that extensive chains scission be avoided because it can lead to side-effect by forming sticky matter, resulting in dropouts. This paper reviews principles of surface preparation of polymer substrate by corona discharging. In addition, the experimental section provides a description of parameter optimization on corona discharging treatment and its side-effect. Experimental results are discussed in terms of surface wetting as determined by contact angle measurements.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.1
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• pp.11-17
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• 2004

This study was conducted to determine the relationship of stomatal responses, photosynthesis, and intercellular $CO_2$ concentration( $C_{i}$) of Betula Species to ozone exposure. Five Betula Species(B. costata, B. davurica, B. schmidtii, B. platyphylla var, iaponica and B, ermani) were grown in the greenhouse. One-year-old potted seedlings of the five Betula Species were exposed to ozone(100 pub) for 8 hours da $y^{-1}$ for 5 weeks in a fumigation chamber. Net photosynthesis was significantly different among species and treatments from early in the period of the fumigation. Stomatal conductance and transpiration rate differences among species and treatments became significant after three weeks of fumigation. $C_{i}$ was significantly different only among treatments; $C_{i}$ of four species, except for B. davurica, was higher than that of control plants. Carboxylation efficiency and photo-respiration rate were significantly different among species or treatments; carboxylation efficiency and photo-respiration rate of the five Betula Species were decreased by ozone treatment. It was concluded that stomatal closure of Betula Species may be the result of the reduction of photosynthesis and rubisco activity and the resulting increase of $C_{i}$. The higher $C_{i}$ likely resulted from reduced photosynthesis because of physiological processes.ocesses.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.344-351
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• 2023

Purpose: This study aimed to evaluate the effectiveness of a dielectric barrier discharge (DBD) plasma module for sterilizing airborne bacteria in indoor spaces and measure the concentration of ozone generated during plasma discharge. Method: The DBD plasma module was installed in a 76m³ space, and air samples were collected under various discharge times to compare the reduction of airborne bacteria. Result: The results showed a significant decrease in airborne bacteria, ranging from 92.057% to 99.999%, with an average ozone concentration of 0.04 ppm, below the reference value. Conclusion: The study suggests that plasma discharge can be used as a means of preventing the spread of airborne bacteria and viruses, while ensuring safety for human exposure.

• Atmosphere
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• v.21 no.1
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• pp.123-130
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• 2011

In this study, we have analyzed the radiative characteristics of erythemal ultraviolet-B (EUV-B from 1999 to 2005) over the Korean Peninsula. EUV-B measured at Gangneung, Anmyondo, Mokpo, and Gosan represents the measurements from clean areas and that at Seoul represents from a polluted area. The magnitudes of EUV-B increase in proportion to the latitudinal decrease. Monthly mean variation of EUV-B at noon shows the maximum value of $158.5mWm^{-2}$ in August and the minimum value of $36.4mWm^{-2}$ in December in the clean areas. Seasonal mean diurnal variation of EUV-B shows a peak around noon (12:00 ~ 13:00 hr) and its intensity varies along with a season in order of summer > spring > fall > winter. The maximum value of $56.4mWm^{-2}$ in summer is three times higher than that in winter ($14.3mWm^{-2}$). The value of EUV-B in the polluted area is lower than that in the clean areas, resulting from the effects of the blocking, reflection, and scattering of EUV-B due to high concentrations of PM10. UV-B is an essential element to synthesize vitamin D in human body. 200 IU(International Unite) of vitamin D can be formed by an exposure of 6-10% of body surface area to 0.5 MED(Minimal Erythemal Dose). In order to form vitamin D, the calculated exposure times to EUV-B are 15 min. in spring, 12 min. in summer, 18 min. in fall, and 37 min. in winter for the clean areas and 16, 16, 24, and 37 min. for the polluted area.

• Journal of Environmental Health Sciences
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• v.49 no.3
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• pp.149-158
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• 2023

Background: Injury is one of the major health problems in South Korea. Few studies have evaluated both intentional and unintentional injury when investigating the association between exposure to air pollutants and injury. Objectives: We aimed to explore the association between short-term exposure to ambient air pollution and years of life lost (YLLs) due to injury. Methods: Data on daily YLLs for 2002~2019 were obtained from the the Death Statistics Database of the Korean National Statistical Office. This study estimated short-term exposure to particulate matter with an aerodynamic diameter of <10 ㎛ (PM₁₀), particulate matter with an aerodynamic diameter of <2.5 ㎛ (PM_2.5), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃). This time series study was conducted using a generalized additive model (GAM) assuming a Gaussian distribution. We also evaluated a delayed effect of ambient air pollution by constructing a lag structure up to seven days. The best-fitting lag was selected based on smallest generalized cross validation (GCV) value. To explore effect modification by intentionality of injury (i.e., intentional injury [self-harm, assault] and unintentional injury), we conducted stratified subgroup analyses. Additionally, we stratified unintentional injury by mechanism (traffic accident, fall, etc.). Results: During the study period, the average daily YLLs due to injury was 307.5 years. In the intentional injury, YLLs due to self-harm and assault showed positive association with air pollutants. In the unintentional injury, YLLs due to fall, electric current, fire and poisoning showed positive association with air pollutants, whereas YLLs due to traffic accident, mechanical force and drowning/submersion showed negative associations with air pollutants. Conclusions: Injury is recognized as preventable, and effective strategies to create a safe society are important. Therefore, we need to establish strategies to prevent injury and consider air pollutants in this regard.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.93-96
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• 2007

In this paper, the testing equipment for evaluating aging characteristics of outdoor silicone rubber insulator resulting from the environmental aging effect with regards to sunlight(UV) was developed. Influence of sunlight effect aging is seriously increase due to destruction of ozone layer which is occurred by consumption of fossil fuel. For this purpose, silicone rubber was aged under the artificial sunlight by exposure of xenon lamp radiation in the accelerating aging chamber and various test and analysis were performed such as breakdown strength, contact angle. And FT-IR analysis has been followed.