• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.348-361
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• 1991

When reinforcing strip footing on a sand 8round with reticulated root piles, reinforcing effect depends on the length , number, cross sectional area, penetration angle, spacing, and Young's modulus of piles. the mode of action of reinfocement tendons in soil isn't one of carring developed tensile stresses but of anisotropic(uni-directional) reduction or even supression of one normal strain rate. R. H. Bassett and N. C. Last proposed that the reinforcement should be located on the direction of minor strain rate which coincides with the tensile strain rate in the velocity characteristics. Based on this proposal the author carried out a series of 2 - dimentional finite element analysis which varies the parameters mentioned above.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.473-477
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• 2004

Cotton fabric was treated with Cationon UK(tertiary ammonium salt) to improve the dyeability to black tea colorants. In order to investigate the efficacy of Cationon UK for improving dyeing properties of cotton fabric, the effect of Cationon UK treatment conditions and dyeing conditions on dye uptake of the cotton fabrics treated with Cationon UK were examined and the colorfastness to washing, perspiration, rubbing and light was also evaluated for practical uses. Cationized cotton treated with Cationon UK showed high dye uptake at lower dyeing concentration and shorter dyeing time, compared with untreated. Dyeing temperature did not affect significantly dye uptake and the maximum dye uptake was obtained at pH 5. Most colorfastness was relatively good, showing 4/5∼5 rating.

• Tribology and Lubricants
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• v.28 no.6
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• pp.289-296
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• 2012

Atomic force microscopy (AFM) has been used for imaging surfaces and measuring surface forces at the nano-scale. Force calibration is important for the quantitative measurement of forces at the nano-scale using AFM. Normal force calibration is relatively straightforward, whereas the lateral force calibration is more complicated since the lateral stiffness of the cantilever is often comparable to the contact stiffness. In this work, the lateral force calibrations of the rectangular cantilever were performed using torsional Sader's method, thermal noise method, and wedge calibration method. The lateral optical lever sensitivity for the thermal noise method was determined from the friction loop under various normal forces as well. Experimental results showed that the discrepancies among the results of the different methods were as large as 30% due to the effect of the contact stiffness on the lateral force calibration of the cantilever used in this work. After correction for the effect of contact stiffness, all the calibration results agreed with each other, within experimental uncertainties.

• Tribology and Lubricants
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• v.29 no.3
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• pp.160-166
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• 2013

There is an indispensable need for force calibration for quantitative nanoscale force measurement using atomic force microscopy. Calibrating the normal force is relatively straightforward, whereas doing so for the lateral force is often complicated because of the difficulty in determining the optical lever sensitivity. In particular, the lateral force calibration of a colloidal probe in a liquid environment often has a larger uncertainty as a result of the effects of the epoxy, the location of the colloidal particle on the cantilever, and a decrease in the quality factor. In this work, the lateral force of a colloidal probe using a reference cantilever with a known spring constant was calibrated in a liquid environment. By obtaining the spring constant and the lateral sensitivity at the equator of a spherical colloidal particle, the damage to the bottom surface of the colloidal particle could be eliminated. Further, it was shown that the effect of the contact stiffness on the determination of the lateral spring constant of the cantilever could be minimized. It was concluded that this method can be effectively used for the lateral force calibration of a colloidal probe in a liquid environment.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.2
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• pp.125-129
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• 1983

It is customary to assume that the resistance of a jull at uniform speed may be regarded as the sum of viscous and wavemaking component resistance, or C sub(i)=C sub(v)+C sub(w), where C sub(v) is regarded as a function of Reynolds Number R and C sub(w) a function of Froude Number F. Formulae have been obtained for ∂C sub(w)/∂R, ∂C sub(v)/∂F which may be relevant in seeking theoretical grounds for possible interaction between viscous and wavemaking component resistances. The values of ∂C sub(w)/∂R are small. In general they are smaller than corresponding values of ∂C sub(v)/∂R. But although these values are small it does not follow that they are entirely negligible. The Froude assumption that the rate of change of C sub(w) with R is zero must bel regarded as incorrect.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.2
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• pp.82-93
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• 1991

The objective of this paper is to show that the soil-geotextile interaction needs to he addressed in addition to the usual tensile and modulus properties when the geotextile is being designed for a specific application. The soil-geotextile interaction can be directly assessed by standard direct shear test. The data presented here show that the shear strength paramaters describing the soil-geotextile interface can he greatly influenced by the type of the geotextile. In this investigation, we examined nine different geotextiles of varying construction and surface textures with two standard soil, under five loading conditions, and compared the shear strength and the frictional resistance with the corresponding values of soil itself The following conclusions were drawned from this study. 1. The shear stress-strain curve shows that there are the residual shear stresses at the soil-geotextile interface. Because of the hydraulic gradient between the soil and the geotextile, the excessive pore water can migrate into the geotextile and among the filaments and dissipate through the soil-geotextile interface. 2. The shear strength of the soil-geotextile interface is affected by the moisture content of the soil. At moisture content lower than the optimum water content of the Proctor compaction test, the shear strength of the soil-geotextile interface is greater. 3. The type and surface roughness of the geotextile have the greatest influence on the interface friction angle between the soil and the geotextile.

• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.348-353
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• 2011

Iron fillings which were accumulated around the rail was often the cause of abnormal signal in case of signaling equipment using rail as transmission line. Iron fillings were generated on curved section of railroad due to the friction between rail and wheel, and metro line company urged to find the way to remove these iron fillings, because these were often the cause of abnormal signal. Magnetic device for trapping iron fillings around concrete slab tracks is introduced. The characteristics of magnetic device were analyzed using basic design and numerical analysis method. Magnetic device for trapping iron fillings were examined for application to the train which were operating in commercial line.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.520-526
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• 2016

Squeal noise is a typical brake noise that is annoying to both passengers and pedestrians. Its frequency range is fairly wide from 1 kHz to 18 kHz, which can be distressful to people. The brake squeal noise occurs due to various mechanisms, such as the mode coupling of the brake system, self-excited vibration, unstable wear, and others. In this study, several parameters involved in the generation of a squeal noise are investigated experimentally by using a brake noise dynamometer. The speed, caliper pressure, torque, and friction coefficient are measured as functions of time on the dynamometer. The contact pressure and temperature distributions of the disc and the pad are also measured by using a thermal imaging camera and a pressure mapping system. As a result of the simultaneous measurement of the friction coefficient and squeal amplitude as functions of the velocity, it is found that the onset of the squeal may be predicted from the ${\mu}-v$ curve. It is also found that a non-uniform contact pressure causes instability and, in turn, a squeal. Based on the analysis results, design modifications of the pad are suggested for improved noise characteristics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3596-3601
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• 2015

Enhancement of the existing program for analyzing a pile driven by vibro hammer was tried. Damping effect of dynamic soil resistance and clutch friction were added to the existing governing equation which constitute vibrating system of vibro hammer-pile-soil. Parameters of the modified Ramberg-Osgood model which simulates dynamic load transfer curves for the developed program were recomputed. Comparing the results of the modified program with those of the field tests, pile displacement with time and load transfer behavior were more similar to those of the field test. The penetration rates obtained from the modified program were more close to those of the field test rather than those of the commertical program.

• Journal of the Korean Geotechnical Society
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• v.23 no.2
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• pp.35-45
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• 2007

In this research, artificially cemented sand which is made of a few portland cement and Nak-Dong river sand was researched closely. For providing the fundamental data which is needed in design and analysis of levee material, the shear behavior of cemented sands was investigated by drained triaxial test, and analyzed in accordance with the increase of cement content. The peak strength and elasitc modulus increased and dilation of cemented sand was restricted by the cementation, but after breakage of the cementation, dilation increased, cohesion intercetpt and friction angle increased with the increase of cement content and strain softening behavior appeared in stress-strain curve.