• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.324-329
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• 1999

This study is performed to evaluate an elastic properties of rice straw ash concrete . The following conclusions are drawn ; The ultrasonic pulse velocity is in the range of 4.084 ∼4.336㎧, which has showed abuot the same compared to that of the normal cement concrete. The highest ultrasonic pulse velocity is showed by 5% rice straw ash filled reice straw ash concrete. The dynamic and static modulus of elasticity i sin the range of 294 ${\times}$103 ∼ 347 ${\times}$103 and 266${\times}$ 103 ∼347${\times}$ 103 kgf/$\textrm{cm}^2$ , respectively. It is showed about the same compared to that of the normla cement concrete. The poisson's number of rice straw ash concrete is less than that of the normal cement concrete . The stress-strain curve of concrete which is contained rice straw ash within 10% appear slowly and over 10% appear almost straightly.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.435-442
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• 2002

Fluid Confirmation Tests(FCT) on 1500 ground Anchors install in weathered rock were carried out to investigate upper and lower limit of elastic elongation, frictional resistant of fixed anchor body, mobilized angle between anchor body and soil. All the measured data were analysed and compared with theoretical equations. The frictional angles of diaphragm wall and anchorage system in weathered rock showed nonlinear curve between upper and lower limit of standard elongation. The FCT results indicated that the frictional resistant angles increased with higher values of surcharge load. The quality assurance on the fixed anchor location was investigated by means of measuring elastic elongation during the FCT, and comparing these with theoretical design length, the quality of anchors in this particular site found to be above average standard. The results of this research works with provide valuable guide line on quality assurance of anchors system as well as resonable prediction of friction resistance between the fixed anchor body and the weathered rock.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2458-2467
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• 1996

The rigid-plastic finite element analysis was performed for analysis of ofhot forging and cold sizing of a bevel gear. Two dimensional analysis was carried out to investigate the defect occurrence on vertical symmetric planes during hot forging and three dimensional analysis was to understand the filling behavior on horizontal planes during cold sizing. The involute curve of a tooth was approximated by a circle for convenience in the present analysis. In order to estimate the elastic deformation of the gear and dies during cold sizing, linear elastic finite element analysis was performed. Results of the analysis can be used to predict grain flows and strength distributions in the forged gear, and to design dies and an appropriate preform for the cold sizing.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.578-585
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• 2004

Hardness test is performed for determination of the other properties, such as strength, wear resistance and deformation resistance, as well as hardness itself. And it is performed for prediction of residual lifetime by analysis of hardness reduction or hardness ratio. However, hardness test has limitation that observation of residual indent is needed for determination of hardness value, and that is the reason for not to be widely used in industrial field. Therefore, in this study, we performed researches to obtain Brinell hardness value from quantitative numerical formula by analysing relationship between indentation depths from indentation load-depth curve and mechanical properties such as work hardening exponent, yield strength and elastic modulus.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.33-40
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• 1988

In this study, effects of the density of soil and the confining pressure applied to the soil sample on the elastic moduli of subgrade soils are experimentally analyzed. Through investigation of subgrade materials of domestic expressways, five typical types of subgrade soils are selected for the experiments. A series of unconsolidated undrained triaxial tests is performed on samples prepared with various water contents and densities at the confining pressures of 1.02, 2.04, and $3.06kg/cm^2$. Initial tangent modulus is inferred from the unloading-reloading portion of the stress strain curve obtained during an individual loading-unloading-reloading test. As a result of the analysis, it is found that the effect of the confining pressure on the elastic modulus of subgrade material is well consistent with the equation proposed by Janbu, and that the elastic modulus can be related to the dry unit weight expressing the Janbu constants as exponentiial functions of it. It is also found that the water content has little effect on the elastic modulus for the samples with the degree of saturation less than 70%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.465-474
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• 2008

Generally design of frame structures composed of beam-column member is accomplished by stability evaluation of each member considering the effective buckling length. This study selects a member of the smallest non-dimension slenderness ratio using the buckling eigenvalue calculated by the elastic buckling eigen-value analysis and axial force of the each member, and decides the initial deflection quantity reflected geometric and material nonlinearities from a suggested equation on the base of standard strength curve of Korea Bridge Design Code. Second-order elastic analysis applying the initial deflection is executed and the stability of each member is evaluated and decides ultimate strength. Through examples of eight-stories and four-stories plane frame structures, the evaluation of the stability is compared with the existing method and ultimate strength of the suggested method is compared with ultimate strength by the nonlinear inelastic analysis. Through these procedures, the increasing of effective buckling length by elastic buckling eigenvalue analysis is prevented from a new design method that considers initial imperfections. And the validity of this method is proved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1037-1047
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• 2013

A systematic laboratory compaction testing was performed with the laboratory seismic measurements of the compacted specimens sampled from various compaction fills and was supplemented with in-situ seismic testing to investigate the effects of compaction energy on the elastic wave velocities of the railway roadbed materials. The both variances of the compressive and shear wave velocities with moisture content curve ($V_p$-w and $V_s$-w curves) are similar to the general trend of the density-moisture content curve(${\gamma}_d$-w curve). At the wet side of optimal moisture content (OMC), either $V_p$ or $V_s$ does not significantly increase, which is well reflecting the no gaining in density with the increasing compaction energy exceeding modified-D compaction effort. $V_p$ increases linearly with ${\gamma}_d$ at the dry side of OMC, while it does exponentially at the wet side. The in-situ wave velocities were found to be influenced by the level of confinement and $V_s$ was more sensitive to compaction energy than $V_p$.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.349-356
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• 2002

There has been an increasing trend toward the use of pushover analysis as a tool for evaluating the seismic resistant and safety of a building structure in the performance based earthquake engineering field. The ATC-40 document proposed a nonlinear static procedure based on the Capacity Spectrum Method to determine earthquake-induced demand given the structure pushover curve, which a curve representing base shear versus roof displacement. However, the procedure is conceptually simple, iterative and time consuming method and may sometimes lead to no solution or multiple solutions. A new improved method of seismic performance evaluation for moment frame building, which take into account the previously mentioned deficiencies of currently used elastic design procedures, is presented in this paper. The results of nonlinear static and nonlinear time history analysis of an example high-rise steel moment frame designed by the proposed method are presented and discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.481-486
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• 1998

In this paper, elastic and inelastic behavior of exterior joint of moment-resisting R.C frame with non-seismic detail subjected to reversed cyclic lateral load such as earthquake excitations was investigated. 1/2-scals subassemblage exterior beam-column joint including slab was manufactured based on similitude law. Then, pseudo static test under the displacement control was performed. The results of 1)crack pattern and failure mode, 2)degradation stiffness and strength, energy dissipation capacity from load-displacement hysteresis curve, 3)strain of steel were analysed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.244-249
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• 2002

Rubber seat is extensively used to reduce the vibration of machine or structure. Over the years an enormous effort has been put into developing procedures to provide properties of rubber material for design function. However, there are still a lot of difficulties to analyze static characteristics of rubber components with hyper elasticity and nonlinear large deformation. In this paper material property is obtained by strain-stress curve using a tension test. Mooney-Rivlin Coefficients are gotten by fitting strain-stress curve. The visco-elastic characteristics of refrigerator rubber mount is determined by using ANSYS. And to minimize the rubber stiffness, the rubber seat shape optimization is performed.