• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.2
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• pp.200-210
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• 2018

Objectives: The purpose of this study is to assess the exposure to ozone and total volatile organic compounds(TVOCs) generated during welding work at a shipyard and recommend respiratory protective equipment(RPE) adequate against these hazards. Method: Ozone was collected for about 30 minutes at two-minutes intervals using a direct reading instrument, specifically an ozone analyzer(Serinus 10, Ecotech, Australia). TVOCs were collected for about 30 minutes at three-minute intervals using a portable GC (Alpha 115, Synspec BV, the Netherlands), and were determined simultaneously by area sampling at the welding plume closest to the welder's breathing zone. The total measurements were 162 for ozone($CO_2$ welding 47, TIG 60, stick 55), and 136 for TVOCs($CO_2$ 65, TIG 50, stick 21). Based on these measurements, a literature survey was conducted to assess the adequacy of RPE. Results: Relative to Korean OEL, measurements above STEL 0.2 ppm were 23.4% for $CO_2$, 63.3% for TIG and 14.5% for stick welding. There were significant differences(p=<0.0001) among welding types. Compared with ACGIH peak exposure of 0.4 ppm for ozone, which is not applied in Korea, $CO_2$ welding exceeded it by 10.6%, TIG by 40.0% and stick by 7.3%. Although it was not feasible to compare them directly since there are no Korean OEL, TVOCs had very high levels similar to the concentrations before moving into a new apartment and about 10-20 times the indoor air quality recommendations for some individual measurements. Conclusions: As ozone removal RPE has been recommended in welding environments for a long time(Lunau, 1967), this fact was demonstrated based on the results of the on-site work environment measurements(ozone and TVOCs). In conclusion, for all welding at a shipyard, gas/vapor and particulate combination RPE are recommended. If this is not possible, it should at least be present for TIG welding.

• Environmental Engineering Research
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• v.11 no.6
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• pp.293-302
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• 2006

The reaction of ozone with NOM (Natural Organic Matter) can occur by two different pathways: that involving molecular ozone and by way of reactions with hydroxyl radicals which are produced from the decomposition of molecular ozone. As such, the formation of ketoacids and Assimilable Organic Carbon (AOC) can be controlled by controlling the pathway by which ozone reacts with NOM. The ratios of $[OH{\cdot}]/[O_3]$ ($R_{CT}$ values) were determined under the various ozonation conditions. The $R_{CT}$ values increased with increasing initial ozone concentration. The $R_{CT}$ values (ranges from 10 to $35^{\circ}C$) increased linearly as temperature increased (within the range from 10 to $35^{\circ}C$). However, $R_{CT}$ was independent of hydraulic retention time (HRT). Operational conditions were found to affect the formation of AOC. The conditions where the molecular ozone reaction predominated resulted in an increase in the formation of AOC.

• The Plant Pathology Journal
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• v.16 no.3
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• pp.130-136
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• 2000

Differences in physiological and biochemical responses between sensitive and tolerant rice cultivars to ozone were investigated to develop reliable indications of early ozone damage. Three Korean local rice cultivars -sen-sitive cultivar Dongjin (DJ), moderately tolerant cultivar Hwayeong (HY) and tolerant cultivar Ilmee (IM) were exposed to ozone at the concentrations of 100 nl $\textrm{l}^{-1}$ or 200 nl $\textrm{l}^{-1}$ , 8 h per day for 10 days in a controlled-environment fumigation chamber. The rice cultivars seemed to be endurable to ozone stress at the concentration of 100 nl $\textrm{l}^{-1}$ which is frequently monitored during the growing season in summer. However, severe damage was induced and differential sensitivity was clearly noted among the rice cultivars at the higher ozone concentration. Activation of the glutathion (GR) -ascorbate peroxidase (APX) cycle was likely to be responsible for protection of rice plants against ozone exposure, relating difference in sensitivity of rice cultivars to ozone. Photosynthetic activity appeared to be one of sensitive responses, for which chlorophyll fluorescence and leaf greenness can together provide a very reliable index, a degree of photosynthetic damages by ozone. Formation of malondialdehyde (MDA) was also considered as an indication that can differentiate cultivars sensitivity to ozone. However, the changes in polyamines and total phenolics were not consistent with exposed ozone concentrations and/or ozone sensitivity of the cultivars. The behavior of polyamines and phenolics in the damaged plants at high ozone levels could be interpreted as an indication of ozone injury rather than activation of additional protection mechanisms scavenging active oxygen species formed by ozone. Several responses triggered by ozone could explain the differential sensitivity of the rice cultivars and be used as reliable indications of relative ozone damage to rice plant.

• Journal of Environmental Science International
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• v.14 no.8
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• pp.749-760
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• 2005

This study examines the local ozone photochemistry in the urban air. The photochemical formation and destruction of ozone was modeled using a photochemical box model. For the model prediction of ozone budget, measurements were carried out from an urban monitoring station in Seoul ($37.6^{\circ}N,\;127^{\circ}E$), Korea for intensive sampling time period (Jun. $1\~15$, 2003). Photochemical process is likely to play significant role in higher ozone concentrations during the sampling period. The results of model simulation indicated that photochemical ozone production pathway was the reaction of NO with $HO_2$ while ozone destruction was mainly controlled by a photochemical destruction pathway, a reaction of $H_2O$ with $O(^1D).$ The contribution of NMHCs to formation and destruction of ozone in the urban was significant. This was entirely different from remote marine environment. The rates of net photochemical ozone production ranged from 0.1 to 1.3 ppbv $h^{-1}$ during the study period.

• Atmosphere
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• v.32 no.3
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• pp.247-261
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• 2022

The importance of ozone monitoring has been growing due to the polar ozone depletion and increasing tropospheric ozone concentration over many Asian countries, including South Korea. In-situ measurement of the vertical ozone structure has advantages for ozone research, but observations are not sufficient. In this study, ozonesonde measurements were performed from October to November in Yongin during the GMAP (The GEMS Map of Air Pollution) 2021 campaign. The procedure for ozonesonde preparation and initial analysis of the observed ozone profile are documented. The observed ozone concentrations are in good agreement with previous studies in the troposphere, and they capture the stratospheric ozone distribution as well, including stratosphere-troposphere exchange event. These balloon-borne in situ measurements can contribute to the evaluation of remote sensing measurements such as Geostationary Environment Monitoring Spectrometer (GEMS). This document focuses on providing essential information of ozonesonde preparation and measurement for domestic researchers.

• Research in Plant Disease
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• v.12 no.3
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• pp.272-277
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• 2006

Recycled irrigation water is a primary inoculum source of Phytophthora spp. and is capable of spreading propagules throughout nursery cultivation. Ozonation is commonly used to disinfest the recycled irrigation water; however, ozone has not been fully researched as a disinfectant for this purpose. In this study, zoospores of four species of Phytophthora were exposed for $1{\sim}9$ min to free available ozone at $0.1{\sim}0.3,\;0.5{\sim}0.7,\;0.9{\sim}1.2,\;1.4{\sim}1.7\;and\;1.9{\sim}2.2mg/l$. Zoospores, mycelial fragments, and culture plugs of P. nicotianae also were exposed to ozone concentrations ranging from 0.1 to 2.2 mg/l for periods ranging from 1 to 9 min. In addition, ozonated water was assayed monthly in 2004 and 2005 at two commercial nurseries, and quarterly in the first year at two other nurseries in Suwon, for ozone and survival of pythiaceous species using a selective medium. No zoospores of any species tested survived endpoint free ozone at 1.4 mg/l while limited mycelial fragments of P. nicotianae survived at 1.9 mg/l, and mycelial plugs treated at the same level of ozone were able to produce few sporangia. Phytophthora spp. were recovered only from nursery irrigation water with levels of free ozone at 0.3 mg/l or lower. The results of this study are essential for improving current ozonation sterilization.

• Asian Journal of Atmospheric Environment
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• v.5 no.1
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• pp.29-40
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• 2011

In this study, the effects of an urban thermal environment on air quality were investigated using hourly surface weather observation data and air quality data over six summers from 2000 to 2005 in two cities on the Korean Peninsula. One, the city of Daegu, is representative of basin topography and the other, the city of Busan, represents a coastal area. It is known that the characteristics of an urban thermal environment are represented as an "urban heat island". Here, we focus on the nighttime urban thermal environment, which is called a "tropical night", during the summer. On tropical nights in Busan, the temperature and cloud cover levels were higher than on non-tropical nights. Wind speed did not appear to make a difference even on a tropical night. However, the frequency of southwestern winds from the sea was higher during tropical nights. The prevailing southwest winds in all areas meant an inflow of air from the sea. So at most of the air quality stations, the ozone concentration during tropical nights was lower than during non-tropical nights. In Daegu, the tropical nights had higher temperatures and cloud covers. Despite these higher temperatures, the ozone concentration during the tropical nights was lower than that on non-tropical nights at most of the air quality stations. This feature was caused by low irradiance, which in turn caused an increased cloud cover. Wind speed was stronger during the tropical nights and dispersed the air pollutants. These meteorological characteristics of the tropical nights reduced ozone concentrations in the Daegu Basin.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.509-512
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• 2001

Recently, our country's piggery has been becoming large-sized and crowded gradually in scale. Thus, the environment in a piggery is getting worse, which leads to a drop in livestock's immunoactivity. Therefore, livestocks are exposured to many diseases(stress, hypertension, stomach ulcer etc.). In this paper, our intention is to design a low cost ozone-generating device with high capacity to maintain a reasonable ozone level, that is necessary for cleaning the environment in a piggery, but is not too high to cause any harmful influence to human beings and livestock. The results showed that the UV-lamp tube with baffle has an increase of 25% in ozone generation efficiency compared to without baffle and the short retention time of air or high inlet air rate shows high level of ozone.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.2
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• pp.139-150
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• 1999

The ozone concentrations measured at the National Air Monitoring Stations between 1990 and 1995 were reviewed to detect any anomalies in the measurements. By screening the cases, in which variation of the ozone concentration from the previous measured value is greater than 75ppb, 125 station-days were identified as the test cases for the anomaly test. Historical and parallel consistencies of the measured concentrations were examined by plotting data for each test case. The detected anomalies can be classified into four categories; single outliers, anomalous variations during the startup period, baseline rises, and fluctuations in th diurnal variations. Anomalies were detected in as many as 80 cases among 125 test cases. Because of these anomalies, the number of hours exceeding 100ppb in the areas other than the Greater Seoul Area(GSA) could decrease from 157 to 107. Further studies for developing the methodology for eliminating the abnormal monitoring data are warranted for the data from the National Air Monitoring Stations are official to the both inside and outside of the country.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.203-203
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• 1999

In this paper, high concentration·yield multi-discharge type ozonizer( MDO ) of new discharge type using superposed silent discharge was designed and manufactured. MDO can be consisted with 3 kind of superposed silent discharge type ozonizer( SDO ) in accordance with power supply method that supplying power, which has 180[°] phase difference, to 3 electrodes and double gap. At the moment discharge characteristics and ozone generation characteristics of each SDO were investigated in accordance with quantify of supplied gas, the number of SDO, and the shapes of each SDO. In result ozone generation characteristics of 17185[ppm] and 783[g/kWh] were obtained, and whorl ozone of 17185[ppm] was in contact with dyeing water waste decolonization characteristics was excellent, so it confirmed that MDO could be used as water environment improvement facility.