• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.6
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• pp.95-103
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• 1998

Solutions of geotechnical engineering problems require calculation of deformation and stresses during various stages of loading. Powerful numerical methods are available to make such calculation even for complicated problems. To get accurate results, realistic stress-strain relationships of soil are dependent on a number of factors such as soil type, density, stress level and stress path. Attempts are continuously being made to develope analytical models for soils incorporating all such factors. The nature of stress-path dependency, the principle that governs deformations in sand, and the use of Lade's single work-hardening model for predicting sand response for a variety of stress-paths have been investigated and are examined. The test results and the analyses presented show that under some conditions sand exhibits stress-path dependent behavior. The strains calculated from Lade's single work-hardening model are in reasonable agreement with those measured, but some discrepancies occur. The largest difference between measured and calculated strains occurs for proportional loading with increasing stresses and for stress-path directions.

• Journal of the Optical Society of Korea
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• v.7 no.1
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• pp.13-19
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• 2003

The effects of strain distribution in quantum wire arrays have been analyzed using a finite-element method including both the hydrostatic and shear strain components. Their effects on the optical properties of the quantum wire arrays are assessed for various types of stress profiles by calculating the optical gain and the polarization dependence. The results show unique polarization dependency, which can be exploited either for the single polarization or the polarization-independent operation in quantum wire photonic devices.

• Tunnel and Underground Space
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• v.2 no.1
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• pp.164-176
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• 1992

The conical-ended borehole technique and hemispherical-ended borehole technique are proposed, for the accurate stress measurement within a rock mass. Theory of stress tensor determination and in situ measurement system are presented with successful case examples, and the characteristics of stress distribution within rock masses are examined by the multiple times measurement in a single borehole. Subsequently, the problem in relation to the numerical approach for cavern designing is discussed on the basis of the dependency of the stress discontinuity on the geological discontinuities and so on.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.101-104
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• 2003

Influences of transverse compressive stress on the critical current ( $I_{c}$) in AgMg and AgMn alloy sheathed Bi-2223 tapes were investigated at 77 K and 0 T. The $I_{c}$ degradation behavior depending on sample specifications was discussed in viewpoints of n-value and damage morphology. As a result, Bi-2223 tapes showed a significant drop in $I_{c}$ for stresses greater than 50MPa. The AgMg sheathed Bi-2223 tapes representing higher $I_{c}$ showed a lower $\sigma$$_{irr}$ and a significant $I_{c}$ degradation with increase in compressive stress. There existed a voltage tap separation dependency of the $I_{c}$ degradation behavior caused by the transverse compressive stress.sive stress.s.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1059-1060
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• 2006

The creep behavior of Al-5vol.% SiC composite was investigated. The composite powder was produced by mechanical milling and hot extruded at $450^{\circ}C$ at ratio of 16:1. A creep test was carried out at a constant load at 598, 648, and 673 K. Using the steady-state equations, the threshold stress and the stress exponent of the creep as a function of temperature were determined. The stress exponent was found to be 3 at the temperature of 673 K and 8 at 598 and 648 K. The dependency of the threshold stress to temperature obeys the Arrhenius relationship with the energy term of $29\;kJ\;mole^{-1}$.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.550-559
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• 2014

Hydraulic performance of the 1 inch ball valve have been analyzed based on the three-dimensional Reynolds-averaged Navier-Stokes analysis and an experiment. The experimental test rig of the 1 inch ball valve has been developed to investigate pressure drop for the 1 inch ball valve. The numerical model, which has reliability and effectiveness, has been constructed through the grid dependency test and validation with the results of the experiment. Shear stress transport turbulence model has been used to enhance an accuracy of the turbulence prediction in the pipeline and ball valve, respectively. Effects of the ball valve angle on the flow characteristics and friction performance have been evaluated.

• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.1051-1066
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• 2015

The study aims on the effect of material dependency in elastic- plastic contact models by contact analysis of sphere and flat contact model and wheel rail contact model by considering the material properties without friction. The various materials are selected for the analysis based on Young's modulus and yield strength ratio (E/Y). The simulation software 'ANSYS' is employed for this study. The sphere and flat contact model is considered as a flattening model, the stress and strain for different materials are estimated. The simulation of wheel-rail contact model is also performed and the results are compared with the flattening model. The comparative study has also been extended for finding out the mean contact pressure for different materials the E/Y values between 150 and 660. The results show that the elastic-plastic contact analysis for materials up to E/Y=296.6 is depend on the nature of material properties and also for this material the mean contact pressure to yield strength reaches 2.65.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.2
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• pp.193-197
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• 2002

The frequency dependency of the Rayleigh surface wave was investigated indirectly by measuring the angular dependency of the backward radiation of the incident ultrasonic wave in the abrasion specimens, which was explained in view of the residual stress distribution. The peak intensity of the backward radiation profile decreased and the right half width of the profile increased with an increase of the variational rate of residual stress for the scuffing specimen. The peak intensity was also affected by the surface wave scattering during the propagation around the micro-damages. The peak angle might depend on not only the amount of residual stress but also the micro-structure. The result observed in this study demonstrates the high potential of the backward radiated ultrasound as a tool for the nondestructive evaluation of the subsurface gradients of materials.

• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.82-86
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• 2013

A poled lead zirconate titanate (PZT) cube specimen is subjected to impulse-type compressive stress with increasing magnitude in parallel to the poling direction at four room and high temperatures. During the ferroelastic domain switching induced by the compressive stress, electric displacement in the poling direction and longitudinal and transverse strains are measured. Using the measured responses, linear material properties, namely, the piezoelectric and elastic compliance coefficients, are evaluated by a graphical method, and the effects of stress and temperature are analyzed. Finally, the dependency of the evaluated linear material properties on relative remnant polarization is analyzed and discussed.

• Interaction and multiscale mechanics
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• v.1 no.4
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• pp.437-448
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• 2008

This paper examined the stability of high-dense dislocation substructures (HDDSs) associated with martensite laths in High Cr steels supposed to be used for FBR, based on a series of dislocation dynamics (DD) simulations. The DD simulations considered interactions of dislocations with impurity atoms and precipitates which substantially stabilize the structure. For simulating the dissociation processes, a point defect model is developed and implemented into a discrete DD code. Wall structure composed of high dense dislocations with and without small precipitates were artificially constructed in a simulation cell, and the stability/instability conditions of the walls were systematically investigated in the light of experimentally observed coarsening behavior of the precipitates, i.e., stress dependency of the coarsening rate and the effect of external stress. The effect of stress-dependent coarsening of the precipitates together with application of external stress on the subsequent behavior of initially stabilized dislocation structures was examined.