• Title, Summary, Keyword: Deposition

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Study on the Asymmetric Regional Deposition of Airborne Pollutant Particles in the Human Respiratory Tract (대기오염 입자의 인체 호흡기내 비대칭 국부침전 특성에 관한 연구)

  • 구재학;김종숭
    • Journal of Korean Society for Atmospheric Environment
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    • v.19 no.5
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    • pp.551-560
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    • 2003
  • Particle deposition in human lungs was investigated theoretically by using asymmetric five-lobe lung model. The volumes of each of the five lobes were different, thereby forming an asymmetric lung structure. The tidal volume and flow rate of each lobe were scaled according to lobar volume. The total and regional deposition with various breathing patterns were calculated by means of tracking volume segments and accounting for particle loss during inhalation and exhalation. The deposition fractions were obtained for each airway generation and lung lobe, and dominant deposition mechanisms were investigated for different size particles. Results show that the tidal volume and flow rate have a characteristic influence on particle deposition. The total deposition fraction increases with an increase in tidal volume for all particle sizes. However, flow rate has dichotomous effects: a higher flow rate results in a sharp increase in deposition for large size particles, but decreases deposition for small size particles. Deposition distribution within the lung shifts proximally with higher flow rate whereas deposition peak shifts to the deeper lung region with larger tidal volume. Deposition fraction in each lobe was proportional to its volume. Among the three main deposition mechanisms, diffusion was dominant for particles < 0.5 ${\mu}{\textrm}{m}$ whereas sedimentation and impaction were most influential for larger size particles. Impaction was particularly dominant for particles> 8 ${\mu}{\textrm}{m}$. The results may prove to be useful for estimating deposition dose of inhaled pollutant particles at various breathing conditions.

Numerical simulation of wet deposition flux by the deposition model (침적 모형에 의한 습성침적 플럭스 수치모의)

  • 이화운;문난경;임주연
    • Journal of Environmental Science International
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    • v.11 no.12
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    • pp.1235-1242
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    • 2002
  • The purpose of this study is to estimate wet deposition flux and to investigate wet deposition characteristics by using the ADOM model. Wet deposition flux of highly reactive $SO_2$ is estimated by applying observed meteorological parameters and concentrations of chemical species to the ADOM model. Wet deposition is largely dependent on large scale precipitation and cloud thickness. Wet deposition flux of sulfate depends on $SO_2$ oxidation in clouds. When large amount of $SO_2$ is converted to sulfate, deposition flux of sulfate increases, but wet deposition flux of $SO_2$ is small. On the whole, the pattern of sulfate wet deposition flux agrees with the typical pattern of sulfate wet deposition that is high in the summer(July) and low in the winter(January).

An experimental study of heat transfer and particle deposition during the outside vapor deposition process (외부증착공정(OVD)에서 열전달 및 입자부착에 관한 실험적 연구)

  • ;;Kim, Jaeyun;Choi, Mansoo
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.11
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    • pp.3063-3071
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    • 1995
  • An experimental study has been carried out for the heat transfer and particle deposition during the Outside Vapor Deposition process. The surface temperatures of deposited layers, and the rates, efficiencies and porosities of particle deposition were measured. It is shown that the axial variation of the surface temperature can be assumed to be quasi-steady and that as the traversing speed of burner is increased, the deposition rate, efficiency and porosity increase due to the decreased surface temperature. As the flow rate of the chemicals is increased, both the thickness of deposition layers and the surface temperature increase. Deposition rate also increases, however, deposition efficiency decreases for tests done. Later passes in early deposition stage result in higher surface temperatures due to increased thickness of porous deposited layers, which cause the deposition rate, efficiency, and porosity to decrease.

Measurement of Nitrogen and Sulfur Deposition to Lake Paldang (팔당호로의 질소와 황성분 침적 측정)

  • Ghim Young Sung;Jin Hyoun Cheol
    • Journal of Korean Society for Atmospheric Environment
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    • v.21 no.1
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    • pp.39-48
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    • 2005
  • Nitrogen and sulfur deposition was measured on Lake Pal dang from March 2002 to October 2003. Wet and dry depositions were separately measured using wet- and dry-only samplers, respectively. In order to measure the dry deposition to the water body, a dry deposition sampler composed of three pans filled with pure water, called the deposition water, was used. Since ammonium was generally in excess in ambient air, more than half of ammonium was present in the gaseous form. Ammonium concentration was also generally higher than the sum of major anion concentrations in the deposition water because gaseous species were much easily deposited than the species in fine particles. Nevertheless, the contribution of gaseous ammonia to the deposition of ammonium was not high as well as that of particulate ammonium while the contribution of gaseous nitric acid was much higher than that of particulate nitrate. Annual wet deposition fluxes of nitrogen and sulfur were five and six times higher than their dry deposition fluxes, respectively. Except for ammonium, the dry deposition flux estimated in the present work was a half of the previous results. This was mainly caused by much smaller dry deposition velocities over the water than over the ground.

A Study on Buffered Deposition Device Structure to Improvement for High Density Chip Realiability (고밀도 칩 신뢰성 개선을 위한 buffered deposition 소자구조에 관한 연구)

  • Kim, Hwan-Seog;Yi, Cheon-Hee
    • Journal of the Korea Society for Simulation
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    • v.17 no.2
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    • pp.13-19
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    • 2008
  • New Buffered deposition is proposed to decrease junction electric field in this paper. Buffered deposition process is fabricated after first gate etch, followed NM1 ion implantation and deposition & etch nitride layer. New Buffered deposition structure has buffer layer to decrease electric field. Also we compared the hot carrier characteristics of Buffered deposition and conventional. Also, we design a test pattern including NMOSFET, PMOSFET, LvtNMOS, High pressure N/PMOSFET, so that we can evaluate DC/AC hot carrier degradation on-chip. As a result, we obtained 10 years hot carrier life time satisfaction.

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Numerical Simulations of Dry and Wet Deposition over Simplified Terrains

  • Michioka, T.;Takimoto, H.;Ono, H.;Sato, A.
    • Asian Journal of Atmospheric Environment
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    • v.11 no.4
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    • pp.270-282
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    • 2017
  • To evaluate the deposition amount on a ground surface, mesoscale numerical models coupled with atmospheric chemistry are widely used for larger horizontal domains ranging from a few to several hundreds of kilometers; however, these models are rarely applied to high-resolution simulations. In this study, the performance of a dry and wet deposition model is investigated to estimate the amount of deposition via computational fluid dynamics (CFD) models with high grid resolution. Reynolds-averaged Navier-Stokes (RANS) simulations are implemented for a cone and a two-dimensional ridge to estimate the dry deposition rate, and a constant deposition velocity is used to obtain the dry deposition flux. The results show that the dry deposition rate of RANS generally corresponds to that observed in wind-tunnel experiments. For the wet deposition model, the transport equation of a new scalar concentration scavenged by rain droplets is developed and used instead of the scalar concentration scavenged by raindrops falling to the ground surface just below the scavenging point, which is normally used in mesoscale numerical models. A sensitivity analysis of the proposed wet deposition procedure is implemented. The result indicates the applicability of RANS for high-resolution grids considering the effect of terrains on the wet deposition.

Measurement of Dry deposition at Seoul, Chunchon and Anmyon-do by Using Filter pack Method (필터팩을 이용한 서울과 춘천, 안면도의 건성 강하량 측정)

  • Kim, Man-Goo;Kang, Mi-Hee;Hong, Young-Min;Park, Ki-Jun;Lee, Bo-Kyung;Lee, Dong-Soo;Kim, San
    • Journal of Korean Society for Atmospheric Environment
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    • v.17 no.1
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    • pp.19-29
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    • 2001
  • Atmospheric concentrations of acidic pollutant were measured by the 4 stage filter pak method at Chunchon and by the 3 stage filter pack method at Seoul and Anmyon-do from January to December 1998. The sample was collected for 24 hours on every Wednesday. Concentrations of particulate matters were highest at Anmyon-do. The particulate concentration was much higher during the warm season than other seasons. While the particulate concentration was higher during the warm season, the concentration of gaseous matter was higher in winter. Dry deposition flux was calculated by using reported deposition velocities and concentration of pollutants measured in this study. The dry deposition velocities used in this study for SO$_2$, SO$_{4}^{2}$, HNO$_3$,NO$_{3}^{-}$ and NH$_3$ were 0.29, 0.15, 2.08( 2.13 only for Anmyon-do), 0.20 and 1.00cm/sec, respectively. At Chunchon, annual sulfur flux originated from dry deposition was 384 kg/$textrm{km}^2$, and the flux from wet deposition was 782kg/$textrm{km}^2$. Dry deposition of sulfur was 33% of total sulfur deposition. The annual nitrogen flux originated from dry deposition was 1,892kg/$textrm{km}^2$. And the flux from wet deposition was 1,066kg/$textrm{km}^2$. Dry deposition of nitrogen was 64% of total nitrogen deposition. Dry deposition as well as wet deposition have to be considerd in the study on acidification of environment such as soil or watershed.

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Size reduction of micro-aperture using additional deposition (부가증착을 이용한 마이크로 구멍의 크기감소)

  • Lee J.S.;Kim G.M.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.505-506
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    • 2006
  • Size reduction of micro-aperture using additional deposition is presented in this study. PECVD process was used for additional deposition. Rate of deposition is different with deposition direction because corners of shadowmask membrane have a taper. Deposition into backside showed better than deposition into frontside with size reduction. Shadowmask membrane with two materials has stress because of the difference of a coefficient of thermal expansion The cantilever of membrane bend to opposite direction of deposition. Deposition to both frontside and backside could reduce inside stress.

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Atomic Layer Deposition-incorporated Catalyst Deposition for the Vertical Integration of Carbon Nanotubes

  • Jung, Sung-Hwan
    • Journal of Electrical Engineering and Technology
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    • v.6 no.5
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    • pp.688-692
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    • 2011
  • Carbon nanotubes (CNTs) are vertically grown inside high-aspect-ratio vertical pores of anodized aluminum oxide. A CNT catalyst layer is introduced by atomic layer deposition to the bottom of the pores, after which the CNTs are successfully grown from the layer using chemical vapor deposition. The CNTs formed a complete vertical conductive path. The conductivity of the CNT-vertical path is also measured and discussed. The present atomic layer deposition-incorporated catalyst deposition is predicted to enable the integration of CNTs with various challenging configurations, including high-aspect-ratio vertical channels or vertical interconnects.

Estimation of Nitrogen and Sulfur Deposition over the Yellow Sea Region (황해 지역의 질소와 황 침적 추정)

  • 김진영;김영성;이승복;문길주
    • Journal of Korean Society for Atmospheric Environment
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    • v.19 no.2
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    • pp.217-229
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    • 2003
  • The amounts of nitrogen and sulfur deposited in the region of the Yellow Sea in both dry and wet forms were estimated by using the measurement data published in tile literature during tile past 10 years. In the estimation of dry deposition, concentrations at ground stations including those at a station on the Chinese side and concentrations from shipboard and aircraft measurements were used as well as deposition velocities. Wet deposition flux was determined at ground stations on the Korean side either by taking the flux data themselves or by calculating them from precipitation data in the literature. The dry deposition flux over the Yellow Sea was much greater than those China was confirmed from the fact that the total amount summing wet and dry depositions exceeded the emission amount from Korea. Dry deposition was principally made in the gaseous form due to a larger deposition velocity. Nevertheless, since the deposition velocity over water was smaller than that over the ground, dry deposition of oxidized nitrogen was smaller than wet deposition. As a whole, wet depositions of nitrogen and sulfur were 2.3 and 1.9 times 1arger than corresponding dry depositions, respectively.