• 한국환경과학회지
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• 제14권8호
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• pp.761-770
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• 2005

Scanning electron microscopy / energy dispersive X-ray analyzer(SEM/EDX) has played an important role for evaluation the source of atmospheric particle because it is a powerful tool for characterizing individual particles. The SEM/EDX system provides various physical parameters like optical diameter, as well as chemical information for a particle-by-particle basis. The purpose of the study was to classify individual particle emitted from the point sources based on clustering analysis and physico-chemical analysis by SEM/EDX. The total of 490 individual particle were analyzed at 8 point sources including coal-fired power plant, incinerator, H-C oil boiler, and metal manufacturing industry. The main components were Si and AI in the coal-fired power plant, Cl and Na in the domestic waste Incinerator, S in the H-C oil boiler and S and Fe in the metal manufactory industry, respectively.

• 상하수도학회지
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• 제19권2호
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• pp.214-220
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• 2005

Errors may occur due to analysis methods and water quality during the application of the on-line particle counter In water treatment process. Errors caused by analysis methods include particle destruction by shear force due to inflow speed and tube friction, as well as interruption by screening, bubbles and contaminants. Since errors happen frequently because of these factors, it is necessary to examine and evaluate such errors during the application of a particle counter. Errors can be large due to screening and bubbles. Measurement values are effective for water analysis after filtration process. However, because of screening, only measurement values for particles above $7{\mu}m$ are valid for water with a turbidity between 3-10NTU. As particle numbers around $10{\mu}m$ increase a lot after ozone treatment, sufficient pretreatment process is necessary. Physical conditions should keep stable for inflow to decrease errors caused by shear force.

• 지질공학
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• 제32권2호
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• pp.241-255
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• 2022

본 연구에서는 예천지역의 화강풍화토에 대하여 KS F 2302의 체 분석 방법과 규정에 준하여 체분석 시험을 수행하고, 물 세척시 발생되는 흙의 입자분리와 입도분포 변화의 특성을 비교 분석하였다. 광학현미경에 의한 영상이미지 분석결과 흙입자가 물에 의해 더 작은 입자로 분리됨을 확인하였고 입도분포곡선의 변화를 5가지 지표값으로 산출한 결과 세립분(0.075 mm)의 증가량은 13.67%, 임의 입경(0.25 mm)의 증가량은 19.44%, 입도분포곡선의 최대통과율폭(B_M)은 #30 체에서 21.08%가 증가되었고 입도분포곡선의 이동면적(A)은 69.28%·mm로 분석되었으며 평균입경(D₅₀)은 0.663 mm가 감소되었다. 이러한 결과는 물 세척을 수행하는 것이 세립토의 함량이 실제보다 과소평가 되는 것을 막을 수 있는 효과적인 방법임을 의미한다.

• 대한기계학회논문집B
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• 제26권12호
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• pp.1715-1721
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• 2002

Numerical analysis was conducted to characterize the gas flow field and particle deposition on a horizontal freestanding semiconductor wafer under the laminar flow field at vacuum environment. In order to calculate the properties of gas, the gas was assumed to obey the ideal gas law. The particle transport mechanisms considered were convection, Brownian diffusion and gravitational settling. The averaged particle deposition velocities and their radial distributions fnr the upper surface of the wafer were calculated from the particle concentration equation in an Eulerian frame of reference for system pressures of 1 mbar~1 atm and particle sizes of 2nm~10$^4$ nm(10 ${\mu}{\textrm}{m}$). It was observed that as the system pressure decreases, the boundary layer of gas flow becomes thicker and the deposition velocities are increased over the whole range of particle size. One thing to be noted here is that the deposition velocities are increased in the diffusion dominant particle size range with decreasing system pressure, whereas the thickness of the boundary layer is larger. This contradiction is attributed to the increase of particle mechanical mobility and the consequent increase of Brownian diffusion with decreasing the system pressure. The present numerical results showed good agreement with the results of the approximate model and the available experimental data.

• 대한기계학회논문집B
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• 제22권4호
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• pp.542-550
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• 1998

A direct contact heat exchanger using particle-suspended gas as a heat transfer medium is analyzed with an extended emphasis on the radiation, i. e., considering the radiation by both gas and particles. While the Runge-Kutta method is used for a numerical analysis of the momentum and energy equations, the finite volume method is utilized to solve the radiative transfer equation. Present study shows a notable effect by the gas radiation in addition to the particle radiation, especially when changing the chamber length as well as the gas and particle mass flow rate. When the gas and particle mass flow rate is raised, the gas temperature in the particle heater still increases as the gas absorption coefficient increases, which is different from the results for the small scale heat exchanger.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.678-679
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• 2006

The effects of particle size on the surface properties of hydro-thermally synthesized barium titanate powders were investigated by means of particle size analysis, specific surface area, SEM, zeta potential and XPS. Particle sizes were measured by laser light scattering and are in the range of 150 to 1100nm. Zeta potential increased with increasing particle size and it was large minus value in the range of particle size from 500 to 900nm, which seems to be related with the dissolution of $Ba^{2+}$ ion in these particle sizes from the analysis of surface properties by XPS.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.755-760
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• 2006

The exhaust gas with solid particle goes through the riser in both particle circulating type and circulating fluidized bed type heat exchanger to recover the heat. During heat transfer, gas velocity in vertical riser decreases as viscosity of exhaust gas decreases. In this case, when the particle size is fixed, sometimes the exhaust gas happens to have lower velocity which prohibit them to go out of the riser. In this paper the particle motion in vertical Rayleigh flow was studied. The behavior of heat transfer was investigated by means of velocity and temperature distribution. The result from numerical analysis was validated by the experimental results. Fortran code was used to analyze the particle motion in vertical Rayleigh flow.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.9-16
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• 2002

The particles velocity in the instantaneous flow field and velocity change of particles along the jet centerline for various particle diameter in a circular turbulent impingement jet are investigated by using particle image velocimetry(PIV) and an equation of particle motion simplified by terms of inertia forces, drag and gravitational force. The jet Reynolds number was 3300 and 8700, and glass beads of 30,58 and 100$\mu$m in diameter were used. The PIV results show that the direction and size of velocity depends not only on the number density of particle but also on the particle momentum. The results obtained form calculation suggest that the particle velocity near the first impingement region deviated from local air velocity, which accords well with the PIV results. The rebound height of particle increase with the particle diameter. In the second-impingement, particle velocities increased sluggishly with Re=3300 but particle velocities uniformed with Re=8700 in stagnation region.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기설비전문위원
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• pp.105-108
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• 2004

This paper describes the influence of conducting particle in the coaxial cylindrical electrodes under alternating voltage condition investigated using breakdown electric field and electro magnetics simulation method. Simulated particle-location in GIS chamber were the particle on electrode, the particle on enclosure and free moving particle. As results, it was founded that in case of breakdown electric field of the GIS chamber, breakdown electric field of particle on electrode was the lowest, that of free moving particle was middle and that of particle on enclosure was the highest. And in case of the electric field analysis with particle locations, electric field of particle on electrode was the highest that of lifted particle was middle and that of particle on enclosure was the lowest. This results can offer a practical reference ra the insulation design of domestic GIS.

• 한국안전학회지
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• 제39권1호
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• pp.96-103
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• 2024

The demand for mass calculation of offsite consequence analysis to conduct exhaustive single-unit or multi-unit Level 3 PSA is increasing. In order to perform efficient offsite consequence analyses, the Korea Atomic Energy Research Institute is conducting model optimization studies to minimize the analysis time while maintaining the accuracy of the results. A previous study developed a model optimization method using efficient plume segmentation and verified its effectiveness. In this study, we investigated the possibility of optimizing the model through particle size distribution setting by checking the reduction in analysis time and deviation of the results. Our findings indicate that particle size distribution setting affects the results, but its effect on analysis time is insignificant. Therefore, it is advantageous to set the particle size distribution as fine as possible. Furthermore, we evaluated the effect of multithreading and confirmed its efficiency. Future optimization studies should be conducted on various input factors of offsite consequence analysis, such as spatial grid settings.