• Journal of Korean Society for Atmospheric Environment
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• v.15 no.4
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• pp.429-439
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• 1999

In order to assess the chronic impact of tropospheric ozone on vegetation in the Seoul metropolitan area, it is necessary to quantify ozone exposure. Two ozone indices commonly used to relate ozone exposure to injury of vegetation were calculated. SUM06(SUM of hourly concentrations at or above 0.06 ppm) and AOT40(Accumulated exposure Over a Threshold of 40 ppb) which are widely used as ozone indices in the US and Europe were calculated based on hourly ozone concentrations in 5 areas of Seoul and 5 cities of Kyunggido during 1990~1997. Most SUM06 levels were 1~5ppm.hr, however several areas in Northern and Eastern Seoul reached about 5~7 ppm.hr in 1996~1997. AOT40 values were as high as 17~24 ppm.hr. Although measured SUM06 levels would not be expected to significantly impact vegetation, the overall ozone index, as well as annual average, 95th, and 99th percentile have increased continuously over the last 8 years. Often, ozone concentrations are lower in cities where there is a significant NOx concentration, than in outlying rural agricultural areas where NOx scrubbing is not as important. Concentrations greater than 40 ppb, which can cause chronic ozone toxicity to vegetation, were found mostly in the summer and constitutued about 5~15% of total hourly ozone cocentrations.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.1
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• pp.50-62
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• 2011

Temporal trends and spatial distributions of ozone concentrations in Pohang were investigated using data measured at 4 air quality monitoring stations (i.e., Daedo, Jukdo, Jangheung, and Desong) during 2002-2006. The monthly mean ozone concentrations were highest during April and June and decreased during July and August, which follows the typical trend in the Northeast Asia region. The high springtime ozone concentration might have been strongly influenced by the enhanced photochemical ozone production of accumulated precursors during the winter under increased solar radiations. In July and August, ozone levels were decreased by frequent and severe precipitation that caused lower mean monthly solar radiation and efficient wash-out of ozone precursors. This suggests that precipitation is extremely beneficial in the aspect of ozone pollution control. High ozone concentrations exceeding 80ppb dominantly occurred in May and June during the late afternoon between 16:00~17:00. Ozone concentrations were higher in Jangheung and Daesong relative to Daedo and Jukdo, whereas total oxidants $(O_3+NO_2)$ were higher in Jangheung and Daedo. In the suburban area of Daesong, ozone concentrations seem to be considerably higher than those in urban sites of Daedo and Jukdo due to lower ozone loss by NO titration with lower local NO level.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.12
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• pp.1274-1279
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• 2006

The formation characteristics of $BDOC_{rapid}$ and $BDOC_{slow}$ with different ozone dosages for 3 different kinds of waters from Maeri raw water in the down stream of Nakdong river, Hoidong reservoir water in Busan City and treated Maeri raw water(sand filtered) has been investigated in this study. The ozone dosages for producing maximum $BDOC_{total}$ in the Maeri raw water, Hoidong reservoir water and sand filtered water of Maeri were 0.9, 1.1 and 1.4 $mgO_3$/mgDOC respectively. It could be concluded that the ozone dosages for formations of maximum $BDOC_{total}$ were determined by characteristics of water. The ozone dosages for producing maximum $BDOC_{rapid}$ in the Maeri raw water, Hoidong reservoir water and sand filtered water of Maeri were 0.9, 0.9 and 1.0 $mgO_3$/mgDOC respectively that were same or lower than the used ozone dosages for producing maximum $BDOC_{total}$. $BDOC_{slow}$ was being formated and increased continuously with the higher ozone dosages which were the used ozone dosages for maximum formation of $BDOC_{total}$ and $BDOC_{rapid}$. For the best results of a pre-treatment of biofiltration, the optimum ozone dosage ranges in formation of $BDOC_{rapid}/BDOC_{total}$ were $0.6{\sim}1.0\;mgO_3$/mgDOC that were lower than the ozone dosage ranges of $0.9{\sim}1.4\;mgO_3$/mgDOC for the maximum formation $BDOC_{total}$. The reported results indicated that the best and effective ways from economic and technical points of view to determine the optimum ozone dosages of the pretreatment of biofilteration process were investigating and classifying BDOC.

• Journal of Environmental Health Sciences
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• v.19 no.4
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• pp.44-50
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• 1993

This paper has concentrated on estimating the improvement of sludge dewaterability for the application of ozone in sewage treatment plant sludge. The experiment for the study was conducted by batch reactor, contacting ozone (5.0 g O$_3$/hr/l) to waste sludge and measured the Specific Resistance to Filtrate (SRF) varying pH, pressure and reaction time of ozone. And then checked the dissolved solids concentration of flitrate. The results of experiment were as follows: 1. When the total solids concentration of excess sludge was 9, 000 mg/l, the optimum injection rate of ozone was 5.0 g O$_3$/hr/l, and then pressure was 50 cm Hg for the measuring SRF. 2. In the range of pH 3~5, the effect of ozone injection was excellent, but it was unsatisfactory in the range of pH 9~11. Therefore, the ozone injection by acidifying pH level was effective in improving the dewaterability of sludge. 3. It was estimated that the dissolved solids concentration of flitrate was increased in proportion to the injection rate of ozone.

• Polymer(Korea)
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• v.27 no.2
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• pp.98-105
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• 2003

The surface energy and the effect of functional groups on the surface of the ozone-treated low-density polyethylene (LDPE) film were studied. Treatment conditions were treatment time, total amount of transferred ozone, and ozone concentration. The introduction of polar groups on the surface of LDPE film after ozone treatment was confirmed by FTIR-ATR and XPS analyses. Surface fee energy of the LDPE film was examined by a contact angle method. The ozone treated-LDPE film showed a decreased water contact angles about 15$^{\circ}$ mainly due to the increased concentration of oxygen-containing functional groups, which was attributed to the increased surface free energy or $O_{IS}/C_{IS}$Also, the concentrations of the oxygen-containing functional groups on the surface of LDPE film increased with ozone treatment time and concentration, whereas no significant effects were found for the total amount of transferred ozone. From the dyeability test using Kubelka-Munk equation, it was found that the ozone treatment plays an important role in the growth of oxygen-containing functional groups of LDPE film, resulting in the improvement of dyeability for basic dyeing agent.

• Atmosphere
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• v.27 no.3
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• pp.291-300
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• 2017

The monthly-mean irradiance of ultra violet (UV)-B and UV-A observed from 2005 to 2014 and 2012 to 2014, respectively, at noon in Gosan, Jeju, South Korea are analyzed. We compare cloudiness, total ozone, visibility, and relative humidity with an emphasis on the four months from May to August (MJJA), which shows the largest UV radiation. While the incoming UV-B radiation at the top of the atmosphere in Gosan is the largest in June due to the small solar zenith angle, the observed surface UV-B shows an unexpected smaller value in June than those in May, July or August. In June, the meteorological conditions affecting Gosan are completely dominated by cloudiness and thus, frequent overcast seems to determine the minimum UV-B. Another important UV-determining factor is the total ozone, which exhibits a monotonic decrease during MJJA without agreeing to the characteristic feature of UV. The ratio of UV-B to UV-A is not generally influenced by cloudiness. Thus, the ratio is a useful indicator of atmospheric turbidity showing larger values for increasing visibility, except in June. A simple model has been used to estimate surface UV by using the observed ozone and visibility in the cloudless condition. The result shows that UV has the lowest value in June with small variation during MJJA. Model estimation also shows that the different characteristic features observed in July between surface UV-B and UV-A is the result of less absorption of UV-B by ozone than that of UV-A by a smaller amount of total ozone.

• 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.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.490-495
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• 2012

The catalytic effect induced by activated carbon (AC) was evaluated during the phenol treatment using an ozone/AC ($O_{3}/AC$) process. In the case of the addition of AC to the ozone only process, the decomposition efficiency of dissolved ozone and phenol increased with increasing the amount of AC input. It was that the OH radical generated from the decomposition of dissolved ozone by AC had an effect on the removal of phenol. It was shown as the catalytic effect of AC ([$\Delta$phenol]/$[{\Delta}O_{3}]_{AC}$) in this study. The maximum catalytic effect was approximately 2.13 under 10~40 g/L of AC input. It approached to the maximum catalytic effect after 40 min of reaction with 10 and 20 g/L of AC input, while the reaction time reached to the maximum catalytic effect under 30 and 40 g/L of AC input was approximately 20 min. Moreover, the removal ratios of total organic carbon (TOC) for ozone only process and ozone/AC process were 0.23 and 0.63 respectively.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.24 no.1
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• pp.19-27
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• 1996

The ozone layer monitoring program of the Global Environment Laboratory at Yonsei University in Seoul, established as one of the Global Ozone Observing System($GO_3OS$) of the World Meteorological Organization(WMO), has been carried out daily by measuring total ozone and its vertical distribution using a Dobson Ozone Spectrophotometer(Beck #124) since 1984. In this paper, we review the organization and the historical background of ozone measurements in Korea, describe data acquisition and analysis systems, and briefly summarize the results from our ozone observations.

• 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.