• Journal of Plant Biology
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• 제37권3호
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• pp.343-347
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• 1994

In order to compare the adjustment of 6 oak species to water stress, the components of water status, tissue elastic modulus, free proline content of leaves and morphological characteristics were determined in pot culture. uercus dentata and . mongolica responded effectively to drought with high root : shoot (R/S) ratio or maintenance of high turgor pressure by large and fast osmotic adjustment and . variabilis with maintenance of high turgor pressure by low elastic modulus under drought. Meanwhile, . aliena and . serrata responded effectively with low omotic potential (Ψo) at full saturation and . acutissima with long root in spite of rigid cell wall and high osmotic potential (Ψo) at full saturation. Proline content in leaves of . dentata, . mongolica and . aliena increased early and rapidly at high leaf water potential (Ψleaf). The results indicate that 6 oak species have adjustment different from each other to water stress.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.505-508
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• 2006

This experimental study is to evaluate the effects of recycled coarse aggregate replacement level on the mechanical properties of concrete produced at Batcher plant. The main test parameter was replacement level of recycled coarse aggregate with the ratio of 0, 30, 60 and 100% to the natural coarse aggregate. From the test results, it was found that compressive strength, elastic modulus and splitting strength are decreased with the increased proportion of replacement level. Therefore, some design coefficients or recommendations for elastic modulus and splitting strength of concrete need to be reconsidered with minor reduction factor of '0.85'.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.769-772
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• 2006

The effects of high temperature on strength, elastic modulus and strain at peak stress of concrete were experimentally investigated. The type of test was the stressed test that a preload was applied to the specimen prior to heating and the load was sustained during the heating period. In this study, the level of preload was 25% of compressive strength at room temperature. All tests were conducted at various temperatures(20,100, 200, 300, 400, 500, 600 and $700^{\circ}C$) for concretes made with W/B ratios 46% and 32%. Test results showed that on the whole, the relative values of strength and elastic modulus, and the real strain value at peak stress were not influenced by the W/B ratio.

• 대한기계학회논문집A
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• 제28권5호
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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.

• Structural Engineering and Mechanics
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• 제5권2호
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• pp.193-207
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• 1997

Experimental tests are described on three ring stiffened machined circular cylinders and three ring stiffened machined circular cones, which were tested to destruction under uniform external pressure. All six vessels failed by inelastic general instability. The experiments showed that the vessels initially deformed plastically at mid-bay in the circumferential direction, and this caused the circumferential tangent modulus to become much less than the elastic Young's modulus, causing the vessels to fail through plastic general instability at pressures much less than that predicted by elastic theory. Based on a thinness ratio, two semi-empirical design charts are provided, which are intended to be used for design purposes in conjunction with the finite element method and a plastic reduction factor.

• 터널과지하공간
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• 제23권3호
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• pp.212-218
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• 2013

풍화된 응회암 시험편을 모사하기 위하여 최고 예열온도를 200, 400, 600($^{\circ}C$)로 한 예열시험편을 제작하였다. 각 예열시험편에 대한 실내시험을 통해 비중, 흡수율, 탄성파속도, 일축압축강도, 압열인장강도, 탄성계수, 포아송비, 슬레이크 내구성 지수를 측정하였다. 암석에 열을 가하는 경우 물성의 열화가 발생하는 것으로 나타났으나 예외적으로 슬레이크 내구성 지수는 별로 영향을 받지 않는 것으로 평가되었다. P-파 속도와 일축압축강도, 압열인장강도, 탄성계수, 흡수율 간에는 상당한 상관성이 있는 것으로 해석되었으며, P-파 속도를 알면 일축압축강도, 압열인장강도, 탄성계수, 흡수율을 추정할 수 있는 회귀식을 도출하였다.

• 한국도로학회:학술대회논문집
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• 한국도로학회 2009년도 추계학술대회 논문집
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• pp.133-138
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• 2009

• Structural Engineering and Mechanics
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• 제64권1호
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• pp.23-31
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• 2017

In the study, dynamic behavior of laminated orthotropic beams on elastic foundation is investigated. Consistent model presented here combines the finite element solution of the system with SAP2000 software and the calculation of soil parameters with MATLAB software using Modified Vlasov Model type elastic foundation. For this purpose, a computing tool is coded in MATLAB which employs Open Application Programming Interface (OAPI) feature of SAP2000 to provide two-way data flow during execution. Firstly, an example is taken from the literature to demonstrate the accuracy of the consistent FEM-Vlasov Model. Subsequently, the effects of boundary conditions, subsoil depth, elasticity modulus of subsoil, slenderness ratio, velocity of moving load and lamination scheme on the behavior of laminated orthotropic beams on elastic foundation are investigated on a new numerical example. It can be concluded that it is really convenient to use OAPI feature of SAP2000 to model this complex behavior of laminated orthotropic beams on elastic foundation under moving load.

• Advances in materials Research
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• 제7권3호
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• pp.163-174
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• 2018

This article studies the free and forced vibrations of the carbon nanotubes CNTs embedded in an elastic medium including thermal and dynamic load effects based on nonlocal Euler-Bernoulli beam. A Winkler type elastic foundation is employed to model the interaction of carbon nanotube and the surrounding elastic medium. Influence of all parameters such as nonlocal small-scale effects, high temperature change, Winkler modulus parameter, vibration mode and aspect ratio of short carbon nanotubes on the vibration frequency are analyzed and discussed. The non-local Euler-Bernoulli beam model predicts lower resonance frequencies. The research work reveals the significance of the small-scale coefficient, the vibrational mode number, the elastic medium and the temperature change on the non-dimensional natural frequency.

• 터널과지하공간
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• 제6권1호
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• pp.1-9
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• 1996

Pocheon granite specimens were thermally treated with cycles of predetermined temperatures ranging 2$0^{\circ}C$ to $600^{\circ}C$. Characterization of thermally-induced microcracks were carried out using optical microscopy and their effect on the various physical & mechanical properties were studied. Generally. uniaxial compressive strength, Young's modulus, Poisson's ratio, elastic wave velocity and specific gravity were found to decrease with increasing temperature. From 30$0^{\circ}C$ upwards, negative lateral strains were observed, which resulted in negative Poisson's ratio. Dynamic Young's modulus and Poisson's ratio were found to be generally most sensitive indicators to thermal cracking.