• 제목/요약/키워드: Concentration Characteristics

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지역 대기질 측정망에 나타난 국내 대기오염도의 최근 동향 -2002년 고농도 사례 및 그 기상 특징 (On the Recent Air Pollution Levels Observed in the Regional Air Monitoring Network -High Air Pollution Concentration Episodes and Their Meteorological Characteristics in 2002)

  • 김철희;박일수;이석조;김정수;진형아;성한규
    • 한국대기환경학회지
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    • 제20권2호
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    • pp.215-224
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    • 2004
  • We report the high concentration episodes for PM$_{10}$, SO$_2$, NO$_2$, and $O_3$ in many urban areas Korea during 2002. The high concentration episodes are identified based on the National Ambient Air Quality Standards and the observations obtained from the Regional Air Monitoring Network composed of approximately 160 air pollution monitoring stations located in a number of major or big cities in South Korea including Seoul, Pusan, Daegu, and Incheon cities. The results show that the twenty cases of high concentration episodes in 2002 consists of both ozone warning episodes (6 cases) and high PM$_{10}$ concentration cases (14 cases), and one half of the latter are found to occur in association with the Yellow Sand (Asian Dust) phenomena. The most outstanding characteristics of the reported episodes are the excessively high levels of maximum PM$_{10}$ concentrations during the Yellow Sand period (i.e., exceeding 3,000$\mu\textrm{g}$/㎥ in April, 2002) and their variable occurrence frequencies across seasons. The high ozone concentration episode days are mainly resulting from both the high photochemical reactions and poor ventilations. The high PM$_{10}$ concentration days during non Yellow Sand periods, however, mostly occurred under the influence of synoptic meteorological conditions such as stagnant or slowly passing high pressure centers, and consequently prevailing weak wind speeds over the Korean peninsula. The overall results of our study thus suggest the importance of both synoptic and local meteorological factors for high concentration levels in the major and/or big cities in Korea.n Korea.

국립산림치유원 혼효림에서의 모노테르펜 농도 특성 분석 및 추정식 개발 (Analysis of Monoterpene Concentration Characteristics and Development of an Empirical Formula for Monoterpene in the Mixed Forest of the National Center for Forest Therapy)

  • 이효정;이영희
    • 대기
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    • 제34권2호
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    • pp.187-202
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    • 2024
  • We analyzed the observed characteristics of monoterpene and developed an empirical formula for monoterpene concentration in the pine-dominated mixed forest of the National Center for Forest Therapy. Monoterpene was measured at 0800, 1200 and 1700 LST once a month using sorbent tube sampling coupled with thermal desorption gas chromatography and mass spectrometry. Monoterpene concentration is low in winter and shows a maximum in June and July. The major components of monoterpene are alpha-pinene, camphene and beta-pinene. During the warm period from May to November, monoterpene concentration is higher at 0800 and 1700 LST than at 1200 LST. The empirical formula takes into account the vegetation variables, temperature-controlled emission, oxidation processes and dilution by wind. The vegetation variable accounts for the difference in observed monoterpene concentration between two sites. The observed monoterpene concentration normalized by the vegetation variable increases exponentially with air temperature. The oxidation process explains the lower monoterpene concentration at 1200 LST than at 0800 and 1700 LST during the warm period. The monoterpene estimates using the empirical formula shows a correlation of 0.52 with the observation for the development period (2018~2020), while it shows a correlation of 0.72 for the validation year (2021). Such higher correlation for the validation year than for the development period is due to the fact that variability of monoterpene concentration is better explained by air temperature in 2021 than in the development period. However, the developed formula underestimates the monoterpene concentration in May and June, showing the limitation in accurately capturing the monthly variation of monoterpene.

통계모형을 이용한 NO2 농도 예측에 관한 연구 (A study on Estimation of NO2 concentration by Statistical model)

  • 장난심
    • 한국환경과학회지
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    • 제14권11호
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    • pp.1049-1056
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    • 2005
  • [ $NO_2$ ] concentration characteristics of Busan metropolitan city was analysed by statistical method using hourly $NO_2$ concentration data$(1998\~2000)$ collected from air quality monitoring sites of the metropolitan city. 4 representative regions were selected among air quality monitoring sites of Ministry of environment. Concentration data of $NO_2$, 5 air pollutants, and data collected at AWS was used. Both Stepwise Multiple Regression model and ARIMA model for prediction of $NO_2$ concentrations were adopted, and then their results were compared with observed concentration. While ARIMA model was useful for the prediction of daily variation of the concentration, it was not satisfactory for the prediction of both rapid variation and seasonal variation of the concentration. Multiple Regression model was better estimated than ARIMA model for prediction of $NO_2$ concentration.

방전Plasma 반응에 의한 NOx의 안전처리에 관한 연구 (A Study on Safety Treatment of NOx by Discharge Plasma Reaction)

  • 최재욱;야마구마 미즈키
    • 한국안전학회지
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    • 제15권2호
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    • pp.92-96
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    • 2000
  • In this experiment, we studied about concentration characteristics of $NO_x$ and generation of ozone in the reactor of corona discharge type by using mixed gas of $NO/N_2$ and $N_2/O_2$. In the case of the initial NO concentration increased, decrease rate of NO concentration was weakened and discharge input power of minimum NO concentration became high. When NO concentration was high, NO decomposition limit was appeared. And NO reduction rate was decreased, when initial NO concentration and discharge input power increased. When discharge input power was 5W, we could know the most proper energy value for treatment of NO. When the concentration of initial NO increased, generation of ozone decreased and in the case of same concentration of NO, according to discharge input power increase, generation of ozone increased.

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노즐용삭을 고려한 SF6 가스차단기 노즐의 열적회복특성 해석 (Analysis of Thermal Recovery Characteristics for Nozzle of SF6 GCB Considering Nozzle Ablation)

  • 이병윤;송기동;정진교;박경엽
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제54권2호
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    • pp.76-82
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    • 2005
  • In this paper, a method for analyzing the thermal recovery characteristics of the nozzle of gas circuit breaker was described. In order to obtain thermal recovery characteristics, the transient simulation of SF6 arc plasma within the nozzle was carried out. In particular, the nozzle ablation was taken into account by simultaneously solving the PTFE concentration equation with the governing equations such as continuity, momentum and energy equation. After that, post arc current calculation was performed with the rate of rise of recovery voltage changed. From the calculated post arc current, it was possible to suggest the thermal recovery characteristics of the nozzle of gas circuit breaker.

연소로 내 2차공기의 주유동 수직방향 선회분사로 인한 선회류가 스월수에 따른 가스 체류시간과 혼합 특성에 미치는 영향 (Effect of Swirling Flow by Normal Injection of Secondary Air on the Gas Residence Time and Mixing Characteristics in a Combustor)

  • 박상욱;전병일;류태우;황정호
    • 대한기계학회논문집B
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    • 제30권1호
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    • pp.48-56
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    • 2006
  • We investigated gas residence time and mixing characteristics due to various swirl numbers generated by normal injection of secondary air to a lab-scale cylinderical combustor. The residence time was estimated by measuring the temporal pressure difference which was caused by deposition of test particles on a filter media after the injection by a syringe. The mixing characteristics were evaluated by standard deviation value of test gas concentration at different measuring points. The test gas concentration was detected by a gas analyzer. The swirl number of $20{\sim}30$ for ${\theta}=5^{\circ}$ caused long residence time enough to improve mixing characteristics. Numerical calculations were also carried out to understand physical meanings of the experimental results.

오염물질의 특성이 막오염 지수에 미치는 영향 (Effect of Foulant Characteristics on Membrane Fouling Index)

  • 박찬혁;김하나;홍승관
    • 상하수도학회지
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    • 제19권6호
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    • pp.775-780
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    • 2005
  • This study was performed to investigate the effect of foulant characteristics on Membrane fouling index such as Silt Density Index (SDI) and Modified Fouling Index (MFI). A linear relationship was found relating the fouling index (both SDI and MFI) on particle concentration, but fouling index values were nonlinearly (exponentially) with increasing organic concentration. When organic matter was the primary cause of fouling, the MFI was not accurately predicted due to internal fouling such as pore adsorption. The fouling index was determined mainly by particle characteristics when both particle and organic coexisted in the feed water. This observation was attributed to lessening of organic pore adsorption by particle cake layer formed on the membrane surface. Bench-scale actual fouling experiments demonstrated that permeate flux declines much faster with feed water containing particles than organic matters although fouling potential predicted by SDI values were identical, indicating that the accurate prediction of fouling potential requires the development of fouling index reflecting different foulant characteristics.

수질환경개선용 고농도·고수율 다중방전형 오존발생기의 특성 (The Characteristics of High Ozone Concentration.Yield Multi-discharge Type Ozonizer for Water Environment Improvement)

  • 송현직;;라만;김영훈;김금영;박원주;이광식
    • 한국조명전기설비학회지:조명전기설비
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    • 제13권2호
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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.

A2O SBBR에서 비포기 시간 배분에 따른 질소-인 제거 특성 비교 (A Comparison of N and P Removal Characteristics by the Variation of Non-aeration Time in A2O SBBR)

  • 박영식;정노성;김동석
    • 한국환경과학회지
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    • 제16권7호
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    • pp.813-821
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    • 2007
  • Laboratory scale experiments were conducted to investigate the removal characteristics of nitrogen and phosphorus in two sequencing batch biofilm reactors (SBBRs). SBBR1 had a short first non-aeration period and SBBR2 had a long first non-aeration period. The removal characteristics of nitrogen and phosphorus in each SBBR were precisely observed according to the variation of influent TOC concentration, and the operation control parameters (pH, DO concentration, ORP) in each reactor were measured. In biological nitrogen removal, there was little difference between SBBR1 and SBBR2 and the nitrogen removal efficiencies were very low. The nitrogen and phosphorus removal characteristics in high influent TOC concentration were different from those in low TOC. Nitrogen removals by simultaneous nitrification/denitrification (SND) were occurred in both SBBR1 and SBBR2. The P removal in SBBR1 was superior to that in SBBR2. The second P release was observed in SBBR1 which had long second non-aeration period.

토질에 따른 Electrokinetic 이온 주입 특성 (Electrokinetic Injection characteristics of Ions into Kaolinite and Sand for Bioremediation)

  • 한상재;이호창;김수삼
    • 한국지하수토양환경학회지:지하수토양환경
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    • 제7권1호
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    • pp.15-24
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    • 2002
  • 현재 원위치 bioremediation을 목적으로 EK (electrokinetlc)기법에 의한 영양분과 TEAs (Terminal electron accepters) 공급이 연구되고 있으나, 아직까지 다양한 토질에서의 EK 주입특성 연구는 미비하다. 따라서 본 연구에서는 카올린과 모래시료에 대하여 영양분인 암모늄이온과 TEAs로서 황산염이온의 EK주입실험을 수행하였다. EK주입에 의한 암모늄이온의 경우 카올린에서는 주입부(양극)에서 높은 농도분포를 보이며, 특별히 모래의 경우는 음극에서 더욱 높은 농도분포를 보인다. 황산염이온의 주입분포는 두 시료에서 모두 균일한 주입분포를 보이지만 두 시료에서의 농도차는 크게 달랐다. 따라서 원위치 bioremediation에 EK 주입기법을 이용할 경우 토질에 따른 주입특성의 평가가 가장 중요하게 고려되어야 한다.