• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.191-193
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• 2000

오존 등 기체상 오염물질의 식물 표면에 대한 건성침적은 식물의 생물학적 활동에 피해를 줄 수 있으며(Runeckles and Chevone, 1992; Chappelka and Chevone, 1992), 건성침적 현상은 노출된 식물지표 환경의 화학적 특성을 변화시키는 작용으로 관심의 대상이 되고있다(Businger, 1986; Galbally et al., 1986; Chang et al., 1987; Wesely, 1989; Hicks et al., 1989). 이러한 기체상 오염물질의 침적현상은 대기질 관리에 있어서 오염물질의 적절한 감소계획을 산정ㆍ평가하기 위하여 지상 오염물질의 농도를 정확하게 추정하는 과정에서 필수적으로 고려되어야 하는 부분이다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.37-38
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• 2001

Polycyclic Aromatic Hydrocarbons(다환방향족 탄화수소류, 이하 PAHs)는 두 개 이상의 벤젠 고리로 구성되어 있는 반휘발성 유기물질로서 가스상과 입자상에 모두 존재한다. PAHs는 주로 불완전 연소에 의해서 생성되며, 주요 고정 오염원은 주거 난방, 코크 산업, 소각이고, 주요 이동오염원은 자동차 엔진이다. PAHs에는 강한 발암성 혹은 돌연변이원성을 가진 화합물들이 포함되어 있고, 주변 대기에 널리 분포되어 있을 가능성이 높기 때문에 일반 대중이 쉽게 노출될 수 있다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.213-214
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• 2001

대기오염 물질은 건성침착과 습성침착의 두 가지 과정에 의해 지표로 침착된다. 습성침착은 구름과 강수과정에 의해 지표로의 침착을 의미하며 건성침착은 오염물질이 직접 지표면에 침착되는 현상을 일컫는다. 본 연구에서는 경기도 이천시 설성면의 16 m 높이의 관측탑에 세 고도에서 관측된 농도 자료와 기상자료를 사용하여 경도법으로 SO$_2$의 건성침착속도를 산출하고 이의 안정도에 따른 특성을 분석하고자 한다. (중략)

• Asian Journal of Atmospheric Environment
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• v.2 no.2
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• pp.81-89
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• 2008

The numerical simulation of wind and ozone ($O_3$) transport in mountainous regions was performed with a computational fluid dynamics technique. A dry deposition model for $O_3$ was designed to estimate $O_3$ deposition in complex terrain, and the qualitative validity of the predicted $O_3$ concentration field was confirmed by comparison with observed data collected with passive samplers. The simulation revealed that wind velocity increases around ridge lines and peaks of mountains. The areas with strong wind corresponded well with the sites of tree decline at high altitudes, suggesting that it is an important factor in the localization of tree/forest decline. On the other hand, there is no direct relationship between forest decline and $O_3$ concentration. The $O_3$ concentration, however, tends to increase as wind velocity becomes higher, thus the $O_3$ concentration itself may be a potential secondary factor in the localized decline phenomena. While the diffusion flux of $O_3$ is not related to localized tree decline, the pattern of advection flux is related to those of high wind velocity and localized tree decline. These results suggest that strong wind with large advection flux of $O_3$ may play a key role in the promotion of tree/forest decline at high mountain ridges and peaks.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.98-99
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• 2012

Deposition of thin films using magnetron sputtering plasmas is a well-developed, classical technology. However, detailed investigations using advanced diagnostics are insufficient in magnetron sputtering, in comparison with plasma-aided dry etching and plasma-enhanced chemical vapor deposition. In this talk, we will show examples of diagnostic works on magnetron sputtering employing metal targets. Diagnostic methods which have fine spatial resolutions are suitable for magnetron sputtering plasmas since they have significant spatial distributions. We are using two-dimensional laser-induced fluorescence spectroscopy, in which the plasma space is illuminated by a tunable laser beam with a planer shape. A charge-coupled device camera with a gated image intensifier is used for taking the picture of the image of laser-induced fluorescence formed on the planer laser beam. The picture of laser-induced fluorescence directly represents the two-dimensional distribution of the atom density probed by the tunable laser beam, when an intense laser with a relatively wide line-width is used. When a weak laser beam with a relatively narrow linewidth is used, the laser-induced fluorescence represents the density distribution of atoms which feel the laser wavelength to be resonant via the Doppler shift corresponding to their velocities. In this case, we can obtain the velocity distribution function of atoms by scanning the wavelength of the laser beam around the line center.

• Korean Journal of Remote Sensing
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• v.38 no.5_3
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• pp.851-861
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• 2022

In this study, we analyzed the effects of trees planted in urban areas on PM_2.5 reduction using a computational fluid dynamics (CFD) model. For realistic numerical simulations, the meteorological components(e.g., wind velocity components and air temperatures) predicted by the local data assimilation and prediction system (LDAPS), an operational model of the Korea Meteorological Administration, were used as the initial and boundary conditions of the CFD model. The CFD model was validated against, the PM_2.5 concentrations measured by the sensor networks. To investigate the effects of trees on the PM_2.5 reduction, we conducted the numerical simulations for three configurations of the buildings and trees: i) no tree (NT), ii) trees with only drag effect (TD), and iii) trees with the drag and dry-deposition effects (DD). The results showed that the trees in the target area significantly reduced the PM_2.5 concentrations via the dry-deposition process. The PM_2.5 concentration averaged over the domain in DD was reduced by 5.7 ㎍ m^-3 compared to that in TD.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.185-187
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• 2000

대기 중의 오염물질들은 지표면 환경과 식생, 농작물, 수면 등의 침적 대상 표면 그리고 생물 활동에 직접적인 피해를 줄 수 있고 토양오염과 수질오염원이 되는 오염물질 유입을 고려해야 하는 환경문제에 있어서 오염물질 농도 예측에 아주 중요한 역할을 한다. 입자상 물질의 건성침적은 습성 침적과 더불어 중금속이나 SO$_4$$^{2-}$ , NO$_3$$^{-}$ 및 NH$_4$$^{+}$와 같은 화합물을 생태계로 전달하여 생태계를 산성화시키거나 부영양화시킬 수 있는 잠재력을 가지고 있음에도 불구하고, 이러한 입자상 물질에 대한 건성 침적은 관측 결과들이 submicron particle들에 대한 침적 속도가 아주 작음을 보여주고 또한 particle들의 침적 과정의 복잡성 때문에 가스상 물질에 대한 건성침적보다 관심을 덜 받고 있다. (중략)

• Asian Journal of Atmospheric Environment
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• v.5 no.2
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• pp.134-143
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• 2011

The present study aimed to investigate the diurnal variations in air concentrations and exchange fluxes of ammoniacal nitrogen ($NH_x$: ammonia ($NH_3$) and particulate ammonium) in a subalpine deciduous forest in central Japan during a week in summer. The $NH_3$ concentrations ($0.50\;{\mu}g\;N\;m^{-3}$ on average) showed a clear circadian variation, i.e., high and low in the daytime and nighttime, respectively. The concentration of particulate ammonium in the coarse fractions was extremely low, whereas that for the PM2.5 fraction was relatively high $0.55\;{\mu}g\;N\;m^{-3}$ on average). The main inorganic ion components of PM2.5 at the study site were ammonium and sulfate. The exchange fluxes of $NH_x$ were bidirectional. Both the maximum and minimum values occurred in the daytime, i.e., $0.39\;mg\;N\;m^{-2}\;hr^{-1}$ of downward flux and $0.11\;mg\;N\;m^{-2}\;hr^{-1}$ of upward flux for $NH_3$ and $0.25\;mg\;N\;m^{-2}\;hr^{-1}$ of downward flux and $0.13\;mg\;N\;m^{-2}\;hr^{-1}$ of upward flux for PM2.5 ammonium. The exchange fluxes of $NH_x$ at night could be considered as zero. The mean deposition velocity during the research period was almost zero for both $NH_3$ and PM2.5 ammonium. The atmosphere-forest exchange of $NH_x$ in the forest during the study period was balanced. The remarkably large deposition of $NH_x$ was attributable to meteorological events such as showers the night before that thoroughly washed the forest canopy and subsequent clear skies in the morning, which enhanced convection. The cleaning effect of rainfall and the rapid change in convection in the early morning should be monitored to evaluate and generalize the gas and particle exchange in a forest.

• Journal of Radiation Protection and Research
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• v.29 no.3
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• pp.173-177
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• 2004

The Chinese cabbage, being one of the principal foodstuffs in Asian countries, is tested for iodine exposure. As a radioactive source, iodine-125 of which the radiological half life is 60 days was used to measure the concentration change. Experiments were carried out four times with different times of exposure. The iodine source was prepared by the chemical reaction of NaI in order to avoid producing relatively large iodine which might be generated In the case of crystal evaporation. The deposition velocity was obtained from the integrated air concentration and surface concentration of the Chinese cabbage. The environmental half life was also calculated.

• Journal of Korea Water Resources Association
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• v.47 no.11
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• pp.1027-1037
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• 2014

Flow and bed changes due to tributary inflow variation at the confluence of the Namhan River and the Geumdang Stream were analyzed in this study using a two-dimensional numerical model. As a result of the numerical analysis, the velocity downstream of the confluence was greater than the velocity upstream of the confluence in the main channel regardless of the magnitude of tributary inflow. However, as tributary discharge increased, the channel erosion was accelerated and the dry area was produced at the tributary. Due to the bed erosion at the tributary, sediment transport was increased and the eroded sediments were deposited in the confluence area. The deposition in the confluence area changed the flow direction at the main channel to the left side and the localized flow eroded the channel bed at the left side. Therefore, it is expected that bank failure due to continuous bed degradation is possible in this area.