• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2315-2328
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• 1993

The turbulence effect of particle deposition on a horizontal free-standing wafer in a vertical flow has been studied numerically by using the low-Reynolds-number k-.epsilon. turbulence model. For both the upper and lower surfaces of the wafer, predictions are made of the averaged particle deposition velocity and its radial distribution. Thus, it is now possible to obtain local information about the particle deposition on a free-standing wafer. The present result indicates that the particle deposition velocity on the lower surface of wafer is comparable to that on the upper one in the diffusion controlled deposition region in which the particle sizes are smaller than $0.1{\mu}m$. And it is found in this region that, compared to the laminar flow case, the averaged deposition velocity under the turbulent flow is about two times higher, and also that the local deposition velocity at the center of wafer is high equivalent to that the wafer edge.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.2
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• pp.130-140
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• 1993

Average particle deposition velocity toward a horizontal semiconductor wafer in vertical airflow is measured by a wafer surface scanner(PMS SAS-3600). Use of wafer surface scanner requires very short exposure time normally ranging from 10 to 30 minutes, and hence makes repetition of experiment much easier. Polystyrene latex (PSL) spheres of diameter between 0.2 and $1.0{\mu}m$ are used. The present range of particle sizes is very important in controlling particle deposition on a wafer surface in industrial applications. For the present experiment, convection, diffusion, and sedimentation comprise important agents for deposition mechanisms. To investigate confidence interval of experimental data, mean and standard deviation of average deposition velocities are obtained from more than ten data set for each PSL sphere size. It is found that the distribution of mean of average deposition velocities from the measurement agrees well with the predictions of Liu and Ahn(1987) and Emi et al.(1989).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.200-209
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• 2008

Particle fluxes were measured with a time-series sediment trap from July 2003 to June 2005 at the St. KOMO(KOMO; Korea Deep-Sea Environmental Study Long-Term Monitoring Station, $10^{\circ}30'N,\;131^{\circ}20'W$) in the northeastern Pacific. Total mass fluxes at a depth of 4,960 m showed distinct seasonal variations with high values in the winter(December-February) and spring(March-May) and low values in the summer(June-August) and fall(September-November). Biogenic origin fluxes also displayed distinct seasonal variations similar to total mass fluxes. Particularly, calcium carbonate fluxes in winter and spring were more than two times greater than those in summer and fall. The prominent seasonal variations of total mass and biogenic fluxes were closely related with the seasonal changes of primary production in the surface waters; in winter and spring, primary production increased due to the enhanced supply of nutrients below the surface mixed layer by strong wind and less stratification, whereas it decreased as a result of the less supply of nutrient by reduced wind speed and strong stratification in summer and fall. The seasonal variations of total mass and biogenic fluxes in this study were higher than the differences of total mass and biogenic fluxes caused by the environmental changes such as El $Ni\tilde{n}o$ and La $Ni\tilde{n}a$ events in the previous studies. In order to understand the effects of El $Ni\tilde{n}o$ and La $Ni\tilde{n}a$ on the particle flux, therefore, the seasonal variation of particle flux in the northeastern equatorial Pacific needs to be well defined.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.102-103
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• 2003

최근 고도 경제성장으로 인한 공업화와 그에 따른 업종이 다양해짐에 따라 여기에 수반되어 발생되는 대기오염물질이 증가할 뿐만 아니라 종류도 여러가지로 다양해지고 있다. 대부분 산업공정에서 배출되는 미세먼지 입자는 기존의 집진장치로 거의 포집제거가 불가능하여 대부분이 대기중으로 방출되고 있는 실정이다. 분진 중에서도 입경 l$\mu\textrm{m}$이하의 분진들은 침강 속도가 작아 거의 gas와 동일한 거동을 하기 때문에 기관 또는 폐포에 침착하여 호흡기에 영향을 미치므로 그 발생량과 화학적 성상이 문제화되고 있는 추세이다. (중략)

• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.34-45
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• 2001

In the persent study, we conducted numerical experiments using a three-dimensional baroclinic equation model and a Lagrangian method for clarifying the hydrodynamics in Osaka Bay under the yearly mean discharge and visualizing the behaviour of particles of different settling velocity discharged from Yodo River and sedimentation pattern on the sea bottom. Particles are transported from the Yodo River to the south direction by the residual circulation of the bay head at the first stage, and after most of suspended solids particles are settled down at any layer and returned in the south-east coastal area through bottom layers by an estuarine circulation. The results show that estuarine circulation plays an important part of suspended solids transportation in the Osaka Bay.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.4
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• pp.303-312
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• 1998

To obtain the solution to the time-dependent particle size distribution of an aerosol undergoing gravitational coagulation, the moment method was used which converts the non linear integro-differential equation to a set of ordinary differential equations. A semi-numerical solution was obtained using this method. Subsequently, an analytic solution was given by approximating the collision kernel into a form suitable for the analysis. The results show that during gravitational coagulation, the geometric standard deviation increases and the geometric mean radius decreases as time increases.

• Journal of the Korean Ceramic Society
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• v.19 no.3
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• pp.199-204
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• 1982

Bowl 형태의 일본산 Nagano 점토에 대한 분류 및 특성화 연구를 하였다. 결정입자 크기를 1$\mu$ 이하로 침강분리 시킨후 전자현미경으로 결정형태를 관찰하였다. 아울러 결정형태, 구조적 결함 및 intercalation 반응성의 상호관계를 검토하기 위하여 tube 형태의 한국산 halloysite 및 plate 형태의 kaolinite를 비교 조사하였다. 특이한 Bowl 형 Nagano 점토는 tube형 halloysite와 화학 반응성에서 동일하여 극성 내지는 hydrogen bridge 결합을 하는 guest 분자와 반응하여 층간삽입 화합물을 형성 하였다. 화학반응성에 따른 점토분류방법에 의해 Nagano 점토가 halloysite임을 밝혔으며 아울러 결정의 형태는 반응성에 영향을 미치지 않음을 알 수 있었다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.145-146
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• 2000

도시와 산업의 발달 및 인구증가로 인하여 다양한 종류의 대기오염물질이 대기 중으로 대량 배출되고 있다. 대기 중의 입자상 및 가스상 오염물질들은 강수, 안개 및 응축 등에 의한 습식침착(wet deposition)과 강수의 영향없이 진행되는 중력침강, 확산, 관성충돌 등에 의한 건식침착(dry deposition) 의 과정에 의해 대기 중에서 제거된다(Legge and Krupa, 1990). 일반적으로 습식침착은 구름 내에서 응핵(nuclei)으로 작용하여 오염물질이 제거되는 rain-out 과정과 비 또는 눈 등의 강하시 충돌, 간섭, 흡수 및 흡착과정에 의해 제거되는 세정과정(wash-out)으로 분류될 수 있다. (중략)

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.154-155
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• 2003

호소 퇴적물은 일반 하천에 비해, 입자성물질의 침강속도가 느리고 한번 퇴적된 물질의 교반이 잘 일어나지 않는 안정된 상태를 유지한다. 그러므로, 퇴적토질의 변화는 수질 변화의 추이를 대변해 줄 가능성이 높다. 소양호는 유역면적 2,703$\textrm{km}^2$, 유로연장 166.2km, 만수면적 70$\textrm{km}^2$으로 국내 최대 상수원 인공호이다. 본 연구에서는 담수 퇴적토의 오염 여부를 판단할 수 있는 생물학적 시험기법들을 활용하여 소양호의 표층 퇴적토질을 평가하였고, 주변잠재오염원의 분포와 비교하였다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.197-198
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• 2001

대기 중 인위적 자연적 발생원에 기인하는 SO$_2$, NOx 및 HCs는 균일반응(homogeneous reaction)과 불균일반응(heterogenous reaction)을 통해서 산화되어 산성가스와 에어로졸을 형성한다. 대부분의 산성물질은 대기 중 구름, 안개, 에어로졸 액적중에서 균일반응을 통해 생성되며, 입자표면에서 가스상 물질의 불균일반응은 에어로졸농도가 높은 배출원 근처에서 국한된다. 이와 같은 반응을 통해 생성된 산성오염물질 및 전구물질은 건성 및 습성침적(dry and wet deposition)을 통해 지표면에 침강되어 생태계에 직ㆍ간접적인 영향을 줄 뿐만 아니라 산성우 및 동식물의 호흡기질환에 중요한 영향을 미친다.(Petros et al., 1989) (중략)