• Title/Summary/Keyword: Ozone distribution

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Ultraviolet Microscopic Study on Lignin Distribution in the Fiber Cell Wall of BCTMP

  • Yoon, Seung-Lak;Yasuo Kojina
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.36 no.1
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    • pp.61-66
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    • 2004
  • Bleached chemithermomechanical pulp (BCTMP) was produced from CTMP of Betula maximowicziana Regel by two staged ozone-hydrogen peroxide bleaching in order to improve the optical properties of high yield pulp. This pulp was used for the evaluation of optical properties improvement, chemical characteristics of lignin in fiber and the relationship between lignin and optical properties in fiber cell wall. Hydrogen peroxide treatment improved the brightness, but the post color number (PC No.). There was little improvement on optical properties by ozone treatment, but this could be improved more by using two staged ozone-hydrogen peroxide bleaching. The hydrogen peroxide treatment did not make any change on chemical characteristics of lignin in cell wall, but by ozone treatment, it was found that the non-aromatic conjugated structure was existed in the surface of cell wall, but this could be removed by hydrogen peroxide treatment in two staged ozone-hydrogen peroxide treatment. Therefore, the optical properties was significantly improved, due to the removal of non-aromatic conjugated structure.

A Study on the Improvement of Decomposition Efficiency of Organic Substances Using Plasma Process and Catalytic Surface Chemical Reaction (플라즈마 프로세스 및 촉매 표면화학반응에 의한 유기화합물 분해효율 향상에 대한 연구)

  • Han, Sang-Bo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.5
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    • pp.932-938
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    • 2010
  • This paper proposed the effective treatment method for organic substances using the barrier discharge plasma process and catalytic chemical reaction followed from ozone decomposition. The decomposition by the plasma process of organic substances such as trichloroethylene, methyl alcohol, acetone, and dichloromethane carried out, and ozone is generated effectively at the same time. By passing through catalysts, ozone easily decomposed and further decomposed organic substances. And, 2-dimensional distribution of ozone using the optical measurement method is performed to identify the catalytic surface chemical reaction. In addition, CO is easily oxidized into $CO_2$ by this chemical reaction, which might be induced oxygen atom radicals formed at the surface of catalyst from ozone decomposition.

Ozone Exposure Assessment by Population Characteristics: A Case Study for High Ozone Days in Busan (인구특성을 고려한 노출평가: 부산지역 고농도 오존일 사례연구)

  • Hwang, Mi-Kyoung;Bang, Jin-Hee;Oh, Inbo;Kim, Yoo-Keun
    • Journal of Environmental Health Sciences
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    • v.41 no.2
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    • pp.71-81
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    • 2015
  • Objectives: Photochemical ozone pollution is associated with increased mortality risk. This study aims to assess the population exposure to ozone according to population characteristics for high ozone days in the Busan metropolitan region (BMR). Methods: The ozone exposure assessment in this study was performed using the WRF-CMAQ simulated ozone concentrations and the population data in the BMR. The settled and daytime population and their activity were considered to conduct the static and dynamic ozone exposure assessment. Results: Applying a static exposure assessment, in case that high ozone occurred throughout Busan area, the highest exposure levels were evaluated in urban neighborhoods. In case of ozone pollution in outer Busan, because sensitive groups have been relatively higher exposure, this case was also evaluated as part of that should not be overlooked. The dynamic exposure was higher than static exposure because the number of population exposed to ozone of high concentration is increased. This approach is important in a regard consider that daytime population distribution when high ozone occur. Conclusion: This study shows the different population exposure according to various ozone distributions for each episode day. Considering demographic characteristic such as population density and activity should be important to understanding the population exposure assessment when ozone pollution occurs.

Numerical Study on the Impact of Meteorological Input Data on Air Quality Modeling on High Ozone Episode at Coastal Region (기상 입력 자료가 연안지역 고농도 오존 수치 모의에 미치는 영향)

  • Jeon, Won-Bae;Lee, Hwa-Woon;Lee, Soon-Hwan;Choi, Hyun-Jung;Kim, Dong-Hyuk;Park, Soon-Young
    • Journal of Korean Society for Atmospheric Environment
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    • v.27 no.1
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    • pp.30-40
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    • 2011
  • Numerical simulations were carried out to investigate the impact of SST spatial distribution on the result of air quality modeling. Eulerian photochemical dispersion model CAMx (Comprehensive Air quality Model with eXtensions, version 4.50) was applied in this study and meteorological fields were prepared by RAMS (Regional Atmospheric Modeling System). Three different meteorological fields, due to different SST spatial distributions were used for air quality modeling to assess the sensitivity of CAMx modeling to the different meteorological input data. The horizontal distributions of surface ozone concentrations were analyzed and compared. In each case, the simulated ozone concentrations were different due to the discrepancies of horizontal SST distributions. The discrepancies of land-sea breeze velocity caused the difference of daytime and nighttime ozone concentrations. The result of statistic analysis also showed differences for each case. Case NG, which used meteorological fields with high resolution SST data was most successfully estimated correlation coefficient, root mean squared error and index of agreement value for ground level ozone concentration. The prediction accuracy was also improved clearly for case NG. In conclusion, the results suggest that SST spatial distribution plays an important role in the results of air quality modeling on high ozone episode at coastal region.

Improvement of a UV/Ozone Duplex Sterilizer (UV/Ozone 복합 살균기의 살균력 개선 연구)

  • Jee, Jung-Eun;Yang, Won-Kyun;Park, Eun-Chul;Kim, Kang-Suk;Joo, Jung-Hoon
    • Journal of the Korean institute of surface engineering
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    • v.41 no.2
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    • pp.76-82
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    • 2008
  • We investigated sterilization characteristics of UV lights by counting the number of bacteria units with varying sterilization time and distance from the light source. We focused on an idea that UV light of 184.9 nm could generate ozone and developed a new sterilizer. The UV-ozone duplex system sterilized bacteria faster than UV-only sterilizers. To reduce shadowing effects by target objects, we used UV transparent quartz plate as a support and put a reflecting plate. Distribution of UV irradiation intensity and ozone supply were analyzed by a 3D model and measured by a semiconductor UV sensor. But even with an Al reflector, multi-layered pens could not be treated properly from UV irradiation only. Ozone generating lamp could treat more uniformly multi-layered pens with a stirring fan by supplying ozone to shadowed surfaces.

Improved Estimation of Hourly Surface Ozone Concentrations using Stacking Ensemble-based Spatial Interpolation (스태킹 앙상블 모델을 이용한 시간별 지상 오존 공간내삽 정확도 향상)

  • KIM, Ye-Jin;KANG, Eun-Jin;CHO, Dong-Jin;LEE, Si-Woo;IM, Jung-Ho
    • Journal of the Korean Association of Geographic Information Studies
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    • v.25 no.3
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    • pp.74-99
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    • 2022
  • Surface ozone is produced by photochemical reactions of nitrogen oxides(NOx) and volatile organic compounds(VOCs) emitted from vehicles and industrial sites, adversely affecting vegetation and the human body. In South Korea, ozone is monitored in real-time at stations(i.e., point measurements), but it is difficult to monitor and analyze its continuous spatial distribution. In this study, surface ozone concentrations were interpolated to have a spatial resolution of 1.5km every hour using the stacking ensemble technique, followed by a 5-fold cross-validation. Base models for the stacking ensemble were cokriging, multi-linear regression(MLR), random forest(RF), and support vector regression(SVR), while MLR was used as the meta model, having all base model results as additional input variables. The results showed that the stacking ensemble model yielded the better performance than the individual base models, resulting in an averaged R of 0.76 and RMSE of 0.0065ppm during the study period of 2020. The surface ozone concentration distribution generated by the stacking ensemble model had a wider range with a spatial pattern similar with terrain and urbanization variables, compared to those by the base models. Not only should the proposed model be capable of producing the hourly spatial distribution of ozone, but it should also be highly applicable for calculating the daily maximum 8-hour ozone concentrations.

The Influences of 5ea Breeze on Surface Ozone Concentration in Pusan Coastal Area, Korea (부산 연안역의 오존 농도에 미치는 해풍의 영향)

  • 김유근;이화운
    • Journal of Environmental Science International
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    • v.5 no.3
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    • pp.265-275
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    • 1996
  • Air pollution characteristics and the influence of sea breeze on surface ozone concentration were studied using the data measured at 7 air quality continuous monitoring stations from June to September using 3 years (1990, 1993, 1994) in Pusan coastal area. Among the 246 sea breeze days for research Period, there were approximately 89 sea breeze days (36%) from lune to September, And there were 120 the episode days (68%) of ozone greater than or equal to 60 ppb in summer season. In 89 sea breeze days, the episode day was highly marked as 56 days (63%). So, we knew that the sea breeze greatly affects the occurence of ozone episode day. the ozone concentration under the condition of the sea breeze increase about 40% in the daytime. Frequencies distribution of $O_3$ concentration for sea breeze moved toward high concentration class. The characteristics of ozone concentration in relation to meteorological conditions of sea breeze is significant because we can discover major weather factors for eastablishing an air pollution- weather forecast system. For further. study about meterological approach method for photochemical air pollution, it is necessary to explain the characteristics of atmosphere below 1, 000 m, especially concerning the formation mechanism of inversion layers. And finally, we will study the relationships to synoptic weather conditions and vertical structure and diurnal variation of local wind systems including sea breeze, and the vertical movements of atmosphere in the city.

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Enzymatic hydrolysis and micro-structure of ozone treated wood meal (오존 처리에 의한 목재 세포벽의 미세구조변화와 효소가수분해)

  • Kim, Kang-Jae;Eom, Tae-Jin
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.42 no.3
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    • pp.67-73
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    • 2010
  • Pine (Pinus densiflora) and aspen (Populus euramericana) wood meals were treated with ozone at various time schedule in acidic condition. The lignin contents and surface area of the ozone treated wood meals were determined and the enzymatic hydrolysis rate of ozonated wood meals was evaluated. The feasibility of enzymatic hydrolysis of the ozone treated wood meal was obviously influenced with the degree of delignification. After ozone treatment of wood meal for 10min, total pore volume were slightly increased in the surface of wood meal. When wood meals were treated with ozone longer than 10min, few change in the pore volume was observed. However, the area of over $50{\AA}$ of pore size is increased with ozonation time. As a conclusion, the rate of enzymatic hydrolysis of wood is more effective with the pore size distribution than the total pore volume.

Environmental Distribution of Air Pollutants and Environmental Risk Assessment in Regional Scale

  • Matsumoto, Fumio;Saito, Mitsugu;Otsuka, Naohiro
    • International Journal of Safety
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    • v.9 no.1
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    • pp.35-42
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    • 2010
  • We measured the concentrations of air pollutants at several residential sites, roadside sites and industrial sites in Iwate Prefecture, Japan. And the concentration distributions of air pollutants were estimated by atmospheric dispersion model using air emissions data. Based on those results, we calculated environmental risk of air pollutants emitted in Iwate Prefecture. As a result, it was found that the surround of factories with high emissions and highly toxic chemicals and the roadsides were high risk area, benzo(a)pyrene, formaldehyde and ozone exceeded the $10^{-5}$ risk level. Moreover, we tried to use "Loss of life expectancy: LLE" for an index to explain those risk to general public intelligibly. The total LLE of the carcinogenic chemicals was about 8.6 hours. Moreover, LLE of ozone was about 9.2 hours. Ozone has a big influence compared with the carcinogenic chemicals.

The Variations of Stratospheric Ozone over the Korean Peninsula 1985~2009 (한반도 상공의 오존층 변화 1985~2009)

  • Park, Sang Seo;Kim, Jhoon;Cho, Nayeong;Lee, Yun Gon;Cho, Hi Ku
    • Atmosphere
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    • v.21 no.4
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    • pp.349-359
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    • 2011
  • The climatology in stratospheric ozone over the Korean Peninsula, presented in previous studies (e.g., Cho et al., 2003; Kim et al., 2005), is updated by using daily and monthly data from satellite and ground-based data through December 2009. In addition, long-term satellite data [Total Ozone Mapping Spectrometer (TOMS), Ozone Monitoring Instrument (OMI), 1979~2009] have been also analyzed in order to deduce the spatial distributions and temporal variations of the global total ozone. The global average of total ozone (1979~2009) is 298 DU which shows a minimum of about 244 DU in equatorial latitudes and increases poleward in both hemispheres to a maximum of about 391 DU in Okhotsk region. The recent period, from 2006 to 2009, shows reduction in total ozone by 6% relative to the values for the pre-1980s (1979~1982). The long-term trends were estimated by using a multiple linear regression model (e.g., WMO, 1999; Cho et al., 2003) including explanatory variables for the seasonal variation, Quasi-Biennial Oscillation (QBO) and solar cycle over three different time intervals: a whole interval from 1979 to 2009, the former interval from 1979 to 1992, and the later interval from 1993 to 2009 with a turnaround point of deep minimum in 1993 is related to the effect of Mt. Pinatubo eruption. The global trend shows -0.93% $decade^{-1}$ for the whole interval, whereas the former and the later interval trends amount to -2.59% $decade^{-1}$ and +0.95% $decade^{-1}$, respectively. Therefore, the long-term total ozone variations indicate that there are positive trends showing a recovery sign of the ozone layer in both North/South hemispheres since around 1993. Annual mean total ozone (1985~2009) is distributed from 298 DU for Jeju ($33.52^{\circ}N$) to 352 DU for Unggi ($42.32^{\circ}N$) in almost zonally symmetric pattern over the Korean Peninsula, with the latitudinal gradient of 6 DU $degree^{-1}$. It is apparent that seasonal variability of total ozone increases from Jeju toward Unggi. The annual mean total ozone for Seoul shows 323 DU, with the maximum of 359 DU in March and the minimum of 291 DU in October. It is found that the day to day variability in total ozone exhibits annual mean of 5.7% in increase and -5.2% in decrease. The variability as large as 38.4% in increase and 30.3% in decrease has been observed, respectively. The long-term trend analysis (e.g., WMO, 1999) of monthly total ozone data (1985~2009) merged by satellite and ground-based measurements over the Korean Peninsula shows increase of 1.27% $decade^{-1}$ to 0.80% $decade^{-1}$ from Jeju to Unggi, respectively, showing systematic decrease of the trend magnitude with latitude. This study also presents a new analysis of ozone density and trends in the vertical distribution of ozone for Seoul with data up to the end of 2009. The mean vertical distributions of ozone show that the maximum value of the ozone density is 16.5 DU $km^{-1}$ in the middle stratospheric layer between 24 km and 28 km. About 90.0% and 71.5% of total ozone are found in the troposphere and in the stratosphere between 15 and 33 km, respectively. The trend analysis reconfirms the previous results of significant positive ozone trend, of up to 5% $decade^{-1}$, in the troposphere and the lower stratosphere (0~24 km), with negative trend, of up to -5% $decade^{-1}$, in the stratosphere (24~38 km). In addition, the Umkehr data show a positive trend of about 3% $decade^{-1}$ in the upper stratosphere (38~48 km).