• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.188-197
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• 2010

This paper presents experimental results of a series of 1-g shaking table model tests performed on end-bearing single piles and pile groups to investigate the effect of particle size on the dynamic behavior of soil-pile systems. Two soil-pile models consisting of a single-pile and a $4{\times}2$-pile group were tested twice; first using Jumoonjin sand, and second using Australian Fine sand, which has a smaller particle size. In the case of single-pile models, the lateral displacement was almost within 1% of pile diameter which corresponds to the elastic range of the pile. The back-calculated p-y curves show that the subgrade reaction of the Jumoonjin-sand-model ground was larger than that of the Australian Fine-sand-model ground at the same displacement. This phenomenon means that the stress-strain behavior of Jumoonjin sand was initially stiffer than that of Australian Fine sand. This difference was also confirmed by resonant column tests and compression triaxial tests. And the single pile p-y backbone curves of the Australian fine sand were constructed and compared with those of the Jumoonjin sand. As a result, the stiffness of the p-y backbone curves of Jumunjin sand was larger than those of Australian fine sand. Therefore, using the same p-y curves regardless of particle size can lead to inaccurate results when evaluating dynamic behavior of soil-pile system. In the case of the group-pile models, the lateral displacement was much larger than the elastic range of pile movement at the same test conditions in the single-pile models. The back-calculated p-y curves in the case of group pile models were very similar in both sands because the stiffness difference between the Jumoonjin-sand-model ground and the Australian Fine-sand-model ground was not significantly large at a large strain level, where both sands showed non-linear behavior. According to a series of single pile and group pile test results, the evaluation group pile effect using the p-multiplier can lead to inaccurate results on dynamic behavior of soil-pile system.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.423-430
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• 2004

This study intended to understand movements of turbid water in selective with drawal reservoirs before and after summer monsoon. Mean rainfall during November-May was low, compared to that during June-October. The reservoir water was discharged through watergates when previous rainfall and inflow exceeded 50 mm and $80\;m^3s^{-1}$, respectively. Intake towers were generally used except for the period of the high runoff. Average turbidity in gown-reservoir showed a difference of 29.9 NTU between premonsoon and postmonsoon. Diameter of particles of turbid water ranged between 0.435 and $482.9\;{\mu}m$. Fine particles such as clay were much denser than the larger particle. In the whole stations, clay component was relatively higher with a proportion of that in the particle distribution. Particle composition of turbid water showed that clay consisted of 94.4-98.9% and silt made of 1.1-5.6%. Analysis on turbid water movements derived from particle distribution showed a linear increase from the deep layer toward the surface layer in lower area of a reservoir. This was closely related with the hydraulic behavior of the reservoir, and heavily affected by the discharges through selective withdrawal towers and watergates. Turbid water originated from stream sediments in the middle area then resuspended in the down-reservoir causing a movement between the surface and middle layers of the reservoir. Therefore, such phenomenon needs to be understood for reservoir water quality management.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.1
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• pp.1-8
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• 2012

To arrange effectively artificial reefs for marine afforestation, tidal currents were analyzed by numerical experiments, and particle tracking based upon tidal currents were carried out to clarify the path of algae spore. The experiments were carried out by EFDC (Environmental Fluid Dynamics Code), and water column was vertically divided 10 layers. Tidal current patterns showed to be affected by main current at outside of study area, and circle currents of two were observed from analysis of residual currents. Particle tracking were experimented for 15 days at 2 installation places in which artificial reefs for marine afforestation would be deployed. According to the results of particle tracking experiment, particle movement at St.1 showed belt type along coastal line, and St.2 showed ellipse type at 300~500 m distant from coastal line. It suggest that artificial reefs for marine afforestation should be installed belt zone at station of St.1 and ellipse zone at St.2. Modelling algae transport was also tested to account for local dispersion of algae spore due to the suspended materials.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.1
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• pp.15-19
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• 2014

Recently, cyclone is used to collect fine particles in various industrial precesses, but many studies are undergoing because of cyclone's low collection efficiency. Thus, we have developed water-cyclone which minimizes disadvantages of existing conventional cyclone and designed 3 different stages depending on precessing materials. Stage 1 collects particles by using principles of conventional cyclone. Stage 2 processes acid gases by extending contact time with water film through vortex movement. Stage 3 processes uncollected substances in stage 1 and 2. Hence, we evaluate water-cyclone by experimental verification.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.177-178
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• 2015

Various vibration caused by construction vehicles and equipment movement, rock blasting, and crushing obstacle occurs inevitably in construction sites. In this study, we measured the impact of vibration by blasting rock at construction sites, rock crushing, concrete crushing. The measuring instrument was installed in adjacent buildings and observed that blasting vibration differs depending on the charge weight, blasting distance, and the measuring position. The observation was maintained by allowable peak particle velocity standard according to each standards and references.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.774-777
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• 2004

A rheology casting technology has some advantages compared with conventional forming processes such as die casting, squeeze casting and hot/cold forming. The liquid segregation is important on mechanical properties of materials using rheology casting. In this study, so, molecular dynamics simulations were performed for the control of liquid segregation. Because the dynamics of fluid flow about nano-scaled materials is completely different from continuum, molecular dynamics simulations were used. The behavior of particles was far from the truth according to boundary conditions in simple flow. But various movement of particles appear at two or more molecular simulations.

• Journal of Environmental Science International
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• v.10 no.5
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• pp.343-350
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• 2001

To investigate air quality away from the coastal urban source region, we used a hybrid Eulerian - Lagrangian method which can describe the formation, transport, transform and deposition processes in complex terrain, with inclusion of shipping sources that were considered to be important emission in the coastal urban region. The result of the Eulerian advection - diffusion prediction was quite similar to that of the Lagrangian particle diffusion prediction. It showed that pollutants emitted from Sasang and Janglim industrial complexes can affect Hwamyeong and the coastal, respectively. During the daytime the concentration was low due to large deposition flux and terrain effect.

• Journal of Power System Engineering
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• v.16 no.6
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• pp.92-97
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• 2012

In this study, ER fluids were working fluid and yield shear stress of attained dispersive ER fluids made by analyzed to adapt effectively at the practical equipment like three port ER valve. In addition, movement of ER particle was observed by using a microscope the same as the strength of electric field with Bingham characteristic. Basis material was presented to develop 3 port ER-Valve by quantitatively comparing and analyzing entrance, load and outlet flow's differences of 3 port rectangular tubes. This study, after designing and producing the 3port ER-Valve, considered the characteristic of pressure drop, outlet and load flow rate by changing the strength of electric field on ER fluids flowing between electrodes.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.245-249
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• 2008

This paper presents a microfluidic cell sizing method using hydrophoretic size-based separation. By exploiting slanted obstacles in a microchannel, we can generate a lateral pressure gradient so that microparticles can be deflected and arranged along lateral flows induced by the gradient. Using such movement of particles, we discriminated 8 to 15 μm-sized beads. We measured the size of U937 cells by comparing the hydrophoretic response of the cells to those of the size-standard beads whose diameters are known. Due to its simple design and fabrication, the sizing method can be easily integrated with other microfluidic components such as cell culture chambers conducting on-chip sizing and sorting.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.2
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• pp.7-15
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• 1997

High shear viscosity at several solids levels was measured for a number of pigment slurries and coating colors containing either anionic or amphoteric latex and analyzed according to Mooney and Eiler equations. Maximum packing fraction and intrinsic viscosity were obtained and compared. Eiler equation provides more credible information than Mooney equation on particle packing and intrinsic viscosity. The packing fraction obtained from Eiler equation was slightly greater than that obtained from static FCC measurement indicating the influence of pigment movement under the dynamic condition. Amphoteric latex caused 4-5% increase of maximum packing fraction of a coating color when its pH is lowered from 7 to 6, while anionic latex did not show any significant change in packing characteristics.