• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.86-91
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• 2001

In lateral ground flow, slope stability, and land slide problems, H-piles have been often used for a horizontally deforming ground to prevent the failure of mass of soil in a downward and outward movement of a slope. Here, Theoretical equations are derived to estimate the lateral force, assuming that the Mohr-coulomb's Plastic states occures in the ground just around H-piles. In this study, the mechanism of lateral force acting on passive pile that is in a row, situated in the ground undergoing plastic deformation was discussed, and its theoretical analysis was carried out considering the interval between H-piles. The solution of the theoretical equation derived from here showed resonable characteristic for constants of soil as well as for the interval, widths, and heights of H-pile.

• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.44-48
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• 2002

In lateral ground flow, slope stability, and land slide problems, H-piles have often been used, on a horizontally deforming ground, to prevent the failure of mass of soil in a downward and outward movement of a slope. Here, theoretical equations are derived to estimate the lateral force, assuming that the Mohr-Coulomb's plastic states occur in the ground, just around H-piles. In this study, some model experiments were performed to check the lateral forces determined from theoretical equations, using several pile widths, heights and various interval ratios between H-piles for sand specimens. The solution of the theoretical equation, derived from previous studies, showed reasonable characteristics for constants of soil, as well as for the interval, widths, and heights of H-Pile.

• 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.

• Journal of Biomedical Engineering Research
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• v.28 no.3
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• pp.377-386
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• 2007

Mechanical loading to bone cells using simple sine wave or constant wave fluid flow has been widely used for in vitro experiments. Human gait is characterized by a complex loading to bones of lower extremities which results from a series of events consisting of heel strike, foot flat and push-off during the stance phase of the gait cycle. Telemetric force analyses have shown that human femora are subject to multiphasic loading. Therefore, it would be ideal if the physiologic loading conditions during human walking can be used for in vitro mechanotransduction studies. Here, for a mechanotransduction study, we develop it fluid flow system (FFS) in order to simulate human physiologic mechanicalloading on bone cells. The development methods of the FFS including the COR (Center for Orthopedic Research), monitor program are presented. The FFS could generate various multiphasic loading conditions of human gaits with output flow. Wall shear distribution was very uniform, with 81 % of the effective loading area of the culture on a glass slide. Our results demonstrated that the FFS, provide a new translational approach for unveiling molecular mechanotransduction pathways in bone cells.

• Korean Journal of Dental Materials
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• v.43 no.1
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• pp.17-28
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• 2016

The aim of this study was to evaluate the changes in dentinal permeability after application of dentin desensitizer on exposed dentin immediately after ultrasonic scaling to teeth with non-carious cervical lesions. Thirty caries-free extracted molars were fixed to slide glasses after horizontally being sectioned at 5 mm below the cemento- enamel junction (CEJ). The prepared specimen was connected to a fluid flow measuring device (nano-Flow), and a V-shaped cavity was formed at the CEJ to imitate the non-carious cervical lesion. After no fluid leakage was confirmed in the connected system with specimen, tooth surface was treated ultrasonic cleaning with piezoelectric ultrasonic scalers until dentinal tubules were exposed. And 6 different desensitizers were applied on exposed dentin. Real-time measurements of dentinal fluid flow were performed during ultrasonic scaling and application of dentin desensitizer. To evaluate the occlusion of exposed dentinal tubules, tooth surface was examined by SEM. Following results were observed. After ultrasonic scaling, more dentinal tubules were exposed on the tooth with non-carious cervical lesions compared to tooth without lesions. The rate of fluid flow measured with nano-Flow system had correlation with the degree of dentin occlusion observed with SEM after application of desensitizers on exposed dentin. Desensitizers with glutaraldehyde and HEMA did not decrease the rate of fluid flow and did not show dentin occlusion. Desensitizers with oxalate showed the limited effects on the rate of fluid flow and dentinal tubule occlusion. Desensitizer with resin monomer showed the significant effect on the rate of fluid flow and dentin occlusion.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.4
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• pp.47-53
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• 2012

It is needed to install a one-way drainage filter to prevent a seepage from lake or river outside of embankment and to promote a drainage from a flood inside of embankment when dikes such as lake dike, river dike, etc are constructed. However, the results of research for one-way drainage filter are insufficient. Therefore, through the field test of one-way drainage filter, this study checked a function of one-way drainage filter with a test of performance. As a result of field test, water flow in dike was blocked in the interception direction of the section that one-way drainage filter was installed, but water passed to the flow allowance direction of the section. Therefore we confirmed the function of one-way drainage filter. Seepage quantity in the flow allowance direction of the one-way drainage filter section was low as 74.6~80.5 % than that in the section without installation of filter because of a reduction effect of seepage with filter. And seepage quantity of field test was low as 64.3~90.0 % than that in results of seepage analysis because the coefficient of permeability of embankment in field is different from the results of laboratory test. In the future, more study will be needed to solve several problems which are related to fix the filter on slide, durability of filter, etc.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.75-82
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• 2012

This paper is the results of analysis for the causes and characteristics of landslide according to heavy rain occurred in west area of Gangwon province which is affected by typhoon such as Ewiniar and Bilis in 2006. West side of Gangwon province is topographically weak for the landslide and debris flow since it is covered by soil of weathered rock such as Gneiss and Granite. From the results of analysis for the rainfall characteristics, it was found that landslide occurrence is closely related to the accumulated rainfall amount less than 3 days. Furthermore, it was found that regional difference of occurrence frequency is effected by 1-hour maximum rainfall intensity. From the results of analysis for the landslide data of 860 locations occurred in west side, it was shown that failure mode was changed from transition slide to liquidity slide. Occurrence frequency was high at the slope angle of $20{\sim}30^{\circ}$ slope length of 11~20, and slope width of 6~10. Landslide of west side is the typical landslide of Gneiss and Granite and the type of small scale which has narrow slope width.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.19-19
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• 2005

This paper reports a novel magnetic force-based microfluidic immunoassay using microbeads and magnetic nanoparticles. The magnetic force-based immunoassay was devised first and successfully applied to detect the rabbit IgG as the model analyte of microfluidic sandwich immunoassay. The microchannels were fabricated by poly(dimethysiloxane) (PDMS) molding processes and bonded on a slide glass by plasma treatment. At the part of the inlet, sample solution was hydrodynamically focused. The focused microbeads of sample solution were flowed through the 150 ${\mu}m$ width channel of outlet. However, when the microbeads are conjugated with the superparamagnetic nanoparticles under the applied magnetic fields, they will switch their flow path and flow through the 95 ${\mu}m$ width channel of outlet. The movements of microbeads conjugated with magnetic nanoparticles were demonstrated by magnetic field $gradients.^{1)}$ High magnetic field gradients using micro electromagnets could be applied to this detection method for high sensitivity and lower detection limit. In addition, the multiplexed $immunoassay^{2)}$ using an encoded microbead which is immobilized with a certain antibody could be possible using this detection principle.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.635-638
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• 2003

For the acute assessment on biological toxicity of wastewater, surface plasmon resonance(SPR) based cell viability detection was performed using gold surface-confined cell as a result of adhesion-modifying chemicals. Escherichia coli O157:H7 (E. coli O157:H7) was investigated after exposure to EDTA. Cells were immobilized on gold coated slide glass for SPR analysis by the method of cross-linking carboxyl group on the bacterial surface with amine group of poly-L-lysine that had been coupled to the gold surface modified by a self-assembled monolayer of 11-mercaptounde canoic acid (11-(MUA)). Reflective intensity of each flow step was changed with respect to confect of ethylenediaminetetraacetic acid (EDTA) disodium salt and phosphate-buffered saline (PBS) solution. The proposed detection technique can be used for biological toxicity test.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.160-165
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• 2002

A study on digital processes of injection mold in reverse engineering are presented. Reverse engineering is useful fur several cases, where user has no geometry information of object. Laser scanner is used to obtaining 3D coordinates of object. Sequences to process cloud data are described; sampling to reduce number of points, sorting to adjust the point order, and fitting to curve and surface, and so on. Split slide structure of mold is used fur undercut part and high viscosity material. Flow of injection molding are analysed to correct cooling channel and simulate molding conditions. NC tool paths are generated to carve core and cavity. The processes are performed in digital data for reduction of lead time and consecutive geometry data.