• Journal of Industrial Technology
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• v.23 no.A
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• pp.157-163
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• 2003

The properties of mechanics and durability of LMC have been performed actively. However, little studies on analysis and properties of thermal expansion has been on the temperature variation. Especially, the low of bonding strength and tensile cracking are caused by difference of thermal expansion between LMC and the substrate concrete. Therefore, this study focused on effect of thermal expansion behavior and properties of LMC according to temperature variation. To identify the property of thermal expansion of LMC, tests of modulus of thermal expansion were carried out at 28 days after casting specimen, subjected to temperature variation between $10^{\circ}C$ and $60^{\circ}C$. The results of this study showed the modulus of elastic of LMC was similar to that of ordinary portland concrete(OPC). It means that stresses caused by difference of modulus of elastic did not occur on interface between LMC and existing concrete. The modulus of thermal expansion of LMC had a little smaller than that of OPC. The modulus of thermal expansion of polymer modified concrete is generally larger than OPC, but the result of this test is disagree with the fact, which may be due to the humidity evaporation difference and aggregate properties.

• International Journal of Railway
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• v.6 no.3
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• pp.112-119
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• 2013

A mid-size RC test apparatus (MRCA) equipped with a program is developed that can test samples up to D=10 cm diameter and H=20 cm height which are larger than usual samples used in practice. Using the developed RC test apparatus, two types of crushed trackbed foundation materials were tested in order to get the shear modulus reduction curves of the materials with changing of shear strain levels. For comparison purpose, large repetitive triaxial compression tests (LRT) with samples of height H=60cm and diameter D=30 cm were performed also. Resilient modulus obtained from the LRT was converted to shear modulus by considering elastic theory and strain level conversion and were compared to shear modulus values from the MRCA. It is found from this study that the MRCA can be used to test the trackbed foundation materials properly. It is found also that strain levels of $E_{v2}$ mostly used in the field should be verified considering the shear modulus reduction curves and proper values of $E_{v2}$ of trackbed foundation must be used considering the strain level verified.

• Journal of Korean Association for Spatial Structures
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• v.18 no.1
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• pp.127-134
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• 2018

This study suggests the tangent modulus $E_t$ associated with partially yielded section of steel member under axially compressed. The provisions for column strength does not provide a information about failure mode of structural system. So, designers can not evaluate that a failure comes from member buckling or material yielding. The material of the axially compressed column under inelastic behavior reaches yielding point before the axial force renders the column bent. If axial members yields not by buckling effect but gradually yielding effect of material, the design code should accept related tangent modulus Et which is based on gradual yielding effect of material. This study provides the new effective tangent modulus $E_t$ derived in the case that residual stress is 30 percent and 50 percent of yielding stress respectively. The study considers idealized I section of steel which ignores web and general I section of steel with web respectively and makes conclude that tangent modulus $E_t$ with idealized I section of steel is rational.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.3
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• pp.458-469
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• 1997

This study was to compare the tensile bond strength and flexibility of four different soft liners(Coe-Soft, Soft Relining, Soft-Liner, Dura Base Soft) before & after thermocycling. Each soft liner was bonded to denture base resin block, and measured the tensile bond strength and modulus of elasticity using Universal testing machine. The mean value of tensile bond strength and modulus of elasticity for each experimental groups were statistically processed by SPSS(Statistical Package of Social Science). The obtained results were as follows : 1. Dura Base Soft had the highest tensile bond strength and Coe-Soft had the lowest tensile bond strength. 2. Coe-Soft had the lowest modulus of elasticity, and Dura Base Soft had the highest modulus of elasticity. 3. Thermocycling had no effects on the tensile bond strength and modulus of elasticity of all the soft liners. 4. The failure modes of Coe-Soft, Soft Relining, Soft Liner were mainly cohesive failure, and that of Dura Base Soft were mainly adhesive failure.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.99-104
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• 2006

Young's modulus of composite has been predicted by Eshelby's equivalent inclusion method modified with Mori-Tanaka's mean field theory, where short fibers of aspect ratio distribution are assumed to be aligned. Young's modulus of the composite is predicted with the smallest class interval for simulating the actual distribution of fiber aspect ratio, which is compared with that computed using different class intervals. Young's modulus of the composite predicted with mean aspect ratio or the largest class interval is overestimated by the maximum 10%. As the class interval of short fibers for predicting Young's modulus decreases, the predicted results show good agreements with those obtained using the actual distribution of fiber aspect ratio. It can be finally concluded from the study that if and only if the class interval of short fiber normalized by the maximum aspect ratio is smaller than 0.1, the predicted results are consistent with those obtained using the actual distribution of aspect ratio.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.146-154
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• 2010

The effects of severe plastic deformation, equal channel angular pressing, and annealing of Al 5052 alloy on elastic modulus have been studied. The AI 5052 alloy was plastically deformed by ECAP method after solution treatment, and then finally annealing heat treated. Elastic modulus was measured by conventional tensile and nano-indentation test, and also measured on the surface of the specimen using acoustic material signature of the acoustic microscope. The variation in the elastic modulus influenced by plastic deformation and heat treatment, inaccessible by the conventional techniques, was successfully measured by acoustic material signature and obtained the elastic modulus depending on crystal orientation at each grain.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.1
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• pp.15-24
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• 2024

Unlike artificially created homogeneous materials, the process of calculating the elastic modulus of natural soil involves the possibility of errors. Because the stress-strain behavior of soil is nonlinear, the secant modulus of elasticity is often used based on 1/2 of the stress at failure. Since soil has the property of changing its elastic modulus depending on the confining pressure, numerical analysis models that analyze its behavior inevitably include complex elements. The hyperbolic model, which relatively accurately simulates the behavior immediately after loading in soft ground, assumes that the stress-strain curve of the consolidated undrained triaxial test is hyperbolic and requires the slope of the tangent line at the starting point. However, the slope of the initial tangent in the stress-strain curve obtained from an actual triaxial test is difficult to have regularity according to changes in confining pressure. Additionally, due to the characteristics of a hyperbola, even small changes in related factors cause large changes in the hyperbola. Therefore, there is a lot of randomness in the process of calculating model parameters from the triaxial test results, which causes large differences in the results. Therefore, the method of calculating the initial elastic modulus by the consolidation test presented in this study is also used to verify the method by the triaxial test. It can be applied. However, since this study was applied to only one sample showing typical consolidation characteristics, it is necessary to check samples with various physical properties in the future.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.6
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• pp.437-443
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• 2009

Impact echo method estimating the soundness of concrete measures the dynamic elastic modulus of specimens which are different with static elastic modulus tested by uni-axial compression test. Thus, this paper investigates the relationships between dynamic and static elastic modulus based on in-situ concrete cores. Also, dynamic elastic modulus was compared with compressive strength. Concrete cores were obtained from about 20 to 70 years concrete structures at three different harbors which were Incheon, Wando, and Masan in Korea. In order to investigate the influence of exposure condition on the relationship, air zone, splash zone, and tidal zone were selected. Different harbors showed the different relationships between dynamic and static elastic modulus, but exposure conditions have no influence on the relationship between dynamic and static elastic modulus. Also, the relationship between dynamic elastic modulus and compressive strength has the same tendency as the relationship between dynamic and static elastic modulus. The relationship equations were proposed to estimate the relationships properly.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.339-349
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• 2019

The relationship between the P wave velocity, static elastic modulus, and dynamic elastic modulus of different rock types was investigated to identify the distributive characteristics of the dynamic elastic modulus. Laboratory and in situ test results from 1,646 rock specimens, which are obtained for design and construction of structure, were analyzed, and grouped into three key rock types: gneiss, granite, and sandstone. These relationships were verified by comparing them with the results from previous studies. The gneiss samples exhibit a linear P wave velocity-static elastic modulus relationship, whereas the granite and sandstone samples exhibit exponential relationships. Their coefficient of determination ($R^2$) values are all in the 0.491-0.642 range, and are similar to those obtained in previous studies. The relationship between the static and dynamic elastic modulus exhibits a linear relationship for all rock types, yielding a coefficient of determination in the 0.543-0.676 range. The relationship between the P wave velocity and static elastic modulus follows an exponential regression for all rock types, with a high coefficient of determination that is in the 0.875-0.940 range.

• Geotechnical Engineering
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• v.6 no.1
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• pp.35-42
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• 1990

Over the years, most pavement designs based on soil strength and permanent strain are almost independent of soil elasticity. However, it was found that plasticity and elasticity of soil have both effected on the failure of pavement structures. The elasticity of soil, hence, using the resilient modulus is reflected for recent pavement design. Although the current AASHTO specifications(1986) for pavement design had changed the soil support value to the resilient modulus, triaxial devices conducting the resilient modulus test have not been fully equipped in a great majority of laboratories. Thus, in the present work, such a resilient modulus is usually derived(from CBR, K values, etc.) by estimating equations. The purpose of this study is to evaluate the resilient modulus of weathered granite soils sampled from 4 points of the central region of Korea by means of AASHTO T 274-82. According to this, some empirical equations for predicting that of the weathered granite soil are proposed and then, the relationship to convert CBR into the resilient modulus is developed.