• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.587-588
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.707-708
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• 2009

• Geomechanics and Engineering
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• v.8 no.6
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• pp.811-828
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• 2015

Proper modelling of the basal resistance terms is key in simulating the motion of fluidized granular flow. In this paper, standard depth-averaged governing equations of granular flow are used together with the classical Coulomb, Voellmy, and velocity dependent friction models (VDFM). A high-resolution modified TVDLF method is implemented to solve the partial differential equations without numerical oscillations. The effects of basal resistance terms on the motion of granular flows such as geometric shape evolution, travel times and final deposits are analyzed. Based on the numerical results, the predictions of the front and rear end positions and developing length of granular flow with Coulomb friction model show excellent agreements with experiment results reported by Hutter et al. (1995), and illustrate the validity of the numerical approach. For the Voellmy model, the higher value of turbulent coefficient than reality may obtain more reasonable predicted runout for the small-scale avalanche or granular flow. The energy exchange laws indicate that VDFM is different from the Coulomb and Voellmy models, although the flow characteristics of both three models fit the measurements and observations very well.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.815-829
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• 2008

Debris flows are a natural hazard which looks like a combination of flood, land and rock slide. Large rainfall in July 2006 produced several large scale debris flows and many small debris flows that resulted in loss of life and considerable property and railway damage, as was widely reported in the national media. The hazard "debris flow" is still insufficiently researched. Furthermore debris flows are very hard to predict. Flexible Ring net barriers are multi-functional mitigation devices commonly applied to rock fall or floating wood protection in floods, snow avalanches and also mud flows or granular debris flows, if properly dimensioned for the process or processes for which they are intended. Overtopping of the barriers by debris flows and sediment transport is possible, supporting the design concept that a series of barriers may be used to stop volumes of debris larger than are possible using only one barrier. The future for these barrier concepts looks promising because these barriers represent the state of art for such applications and are superior to many other available options.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.459-460
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• 2009

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.551-554
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• 2008

In this study, numerical methods for the code development of the interior ballistics have been conducted. Mathematical models and numerical methods for the analysis technique of the granular solid propellants have been investigated. As the results of applying the methods of errors have been generated by calculation for the specific surface area of the granular solid propellants. To remove these error, the developed Eulerian-Larangian method for multiphase flows has been suggested.

• Journal of the Korean GEO-environmental Society
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• v.11 no.8
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• pp.15-23
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• 2010

Debris flows are a natural hazard which looks like a combination of flood, land and rock slide. Large rainfall in July 2006 produced several large scale debris flows and many small debris flows that resulted in loss of life and considerable property and railway damage, as was widely reported in the national media. The hazard "debris flow" is still insufficiently researched. Furthermore debris flows are very hard to predict. Flexible Ring net barriers are multi-functional mitigation devices commonly applied to rock fall or floating wood protection in floods, snow avalanches and also mud flows or granular debris flows, if properly dimensioned for the process or processes for which they are intended. Overtopping of the barriers by debris flows and sediment transport is possible, supporting the design concept that a series of barriers may be used to stop volumes of debris larger than are possible using only one barrier. The future for these barrier concepts looks promising because these barriers represent the state of art for such applications and are superior to many other available options.

• Journal of the Korean Mathematical Society
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• v.51 no.1
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• pp.163-187
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• 2014

We present a multi-stage Roe-type numerical scheme for a model of two-phase flows arisen from the modeling of deflagration-to-detonation transition in granular materials. The first stage in the construction of the scheme computes the volume fraction at every time step. The second stage deals with the nonconservative terms in the governing equations which produces states on both side of the contact wave at each node. In the third stage, a Roe matrix for the two-phase is used to apply on the states obtained from the second stage. This scheme is shown to capture stationary waves and preserves the positivity of the volume fractions. Finally, we present numerical tests which all indicate that the proposed scheme can give very good approximations to the exact solution.

• Applied Microscopy
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• v.28 no.3
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• pp.329-343
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• 1998

Early wound healing responses in the skin of the Korean fire bellied toad, Bombina orientalis, were examined using histochemical , scanning and transmission electron microscopical techniques. Cutaneous wounds were induced by sharp razor blade , and maintained in special cages for up to 3 days. By this treatment whole parts of epithelium and dermis were profoundly affected. After injury, retraction of damaged surface of the skin was observed. At 3 hours after injury, poly-band was form by mucous substance. The wound skin consisted of mucous gland secreted mucous substance which flows into wound cavity and the wound area was sealed by mucous substance which form thick layer at 6 hours. It appeared that natural disposition showed acid and neutral mucous substance by reaction of PAS and Alcian blue (pH 2.5) staining. After formation of the poly-band, epithelial cells were formed by migration of regenerating epithelial cells. These cells moved over the wound surface by migration at 12 hours after wounding. Poly-band was much increased in thickness and migrating cells were completely formed wound closure at 24 hours post-wounding. After 72 hours regenerated epithelial layer consists of four or five cell layers which are similar to clear, granular, and spinous layer.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.6
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• pp.70-75
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• 2010

Compressed air represents an energy source and an force-transmission medium for brake systems on medium-heavy and heavy-duty commercial vehicles. However, one disadvantage is the tendency of air to absorb moisture in the form of water vapor. This water vapor condenses once the air, which is heated during compression, cools back to ambient temperature upon emerging from the air compressor. The resulting condensation assumes the form of moisture in pneumatic lines, air tanks, cylinders and valve assemblies and can have negative consequences for the brake system and vehicle safety. The pneumatic systems on today's vehicles are equipped with air dryers, in which the supplied air is dried according to the adsorption principle. In the systems, the compressed air flows through a granular desiccant with molecular sieves which captures the water molecules.