• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1390-1395
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• 2005

To analyze the effects of oyster shell particles, inserted in the self-hardening matrix such as cement paste, on strength, homogenization analysis using micro structure was used to estimate and assess the apparent elastic modulus of oyster shell particle. DIB modeling technique was used to represent of the micro structure of oyster shell mixed concrete. The results showed that the apparent elastic modulus of LOS (large oyster shell particle) was changed with the amount of LOS inserted. In particular, when the amount of LOS was 200% of the weight of cement, the apparent elastic modulus of LOS tended to decrease rapidly. This could mean that the strength of oyster shell mixed concrete is much affected by LOS inserted material in mixed ratio of 200%.

• 터널과지하공간
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• 제33권3호
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• pp.150-168
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• 2023

암석의 이방성 거동은 조암광물들의 방향성 배열과 미세균열의 분포 특성이 주된 원인이다. 특히, 퇴적암과 변성암은 횡등방성 강도 및 변형 특성을 또렷이 나타내는 경우가 많다. 그러므로 암석역학적 설계과정에서는 횡등방성 암석의 변형 및 파괴 특성을 정확하게 이해하는 것이 중요하다. 횡등방성 암석의 변형은 실내시험을 통해 측정할 수 있는 5개의 독립된 탄성정수를 이용하여 기술된다. 이 연구에서는 문헌에 보고된 실험자료를 이용하여 횡등방성 암석의 겉보기 탄성정수의 방향성 변화 특성을 분석하였다. 임의 방향으로 회전된 직각좌표계에서 겉보기 탄성정수 값을 효율적이고 체계적으로 계산하기 위해 Mehrabadi & Cowin의 구성방정식을 도입하였다. 문헌에 보고된 4개 횡등방성 암석을 선택하여 연약면의 방향 변화가 겉보기 탄성계수, 겉보기 전단 탄성계수, 겉보기 포아송비의 변화에 미치는 영향을 분석하였다. 이러한 분석 결과를 바탕으로 새로운 탄성정수 제약 조건식을 제안하였다. 제안한 제약 조건식을 만족하면 횡등방성 암석에서 겉보기 탄성정수의 방향성 변화는 직관적으로 예측되는 경향과 일치하게 된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 지반환경 및 준설매립에관한 학술세미나
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• pp.72-84
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• 2001

In order to utilize mass of oyster shells for a partial substitute material for reclamation, we investigate the shear characteristics of dredged sluge mixed with oyster shells. the apparent modulus of elasticity of the this mixture are obtained from the triaxial compression tests and is utilized to characterize the apparent modulus of elastic of the oyster shells by carrying out some numerical analysis based upon the homogenization theory. We got the conclusion by a series of experiment, 1) It is verified that modulus of elasticity of dredged clay is improved by mixing with oyster shells. 2) The homogenization method for deducing apparent modulus of elasticity of oyster shells, which can consider micro-structure of mixed soil, is introduced. The elastic modulus is affected from the skeleton structure of oyster shell. The effect of 49kPa is bigger than that of 98kPa.

• Journal of the Korean Wood Science and Technology
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• 제43권2호
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• pp.177-185
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• 2015

The goal of this study is to evaluate the limitation of ASTM D 198 bending and ASTM D 3044 in determination of elastic modulus and shear modulus. Different material properties and span to depth ratios were used to analyze the effects of material property and testing conditions. The ratio of true elastic modulus to apparent elastic modulus evaluated from ASTM D 198 bending sharply decreased with increment of span to depth ratio. Shear modulus evaluated from ASTM D 198 bending decreased with increment of depth, whereas shear modulus evaluated from ASTM D 3044 was hardly influenced by increment of depth. Poisson's ratio influenced shear modulus from ASTM D 198 bending but did not influence shear modulus from ASTM D 3044. Different shearing factor was obtained for different depths of beams to correct shear modulus obtained from ASTM D 198 bending equivalent to shear modulus from theory of elasticity. Equivalent shear modulus of materials could be obtained by applying different shearing factors associated with beam depth for ASTM D 198 bending and correction factor for ASTM D 3044.

• 비파괴검사학회지
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• 제28권3호
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• pp.279-284
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• 2008

The firmness of fruit is one of the most important quality factors and is highly correlated to the elastic modulus. In this study, the ultrasonic transmission method was applied to evaluate the elastic modulus of the apple. In order to transmit and receive the ultrasonic wave through the whole apple, the ultrasonic measurement setup consisted of ultrasonic pulser, two specially fabricated ultrasonic transducers for fruit and digital storage oscilloscope. Ultrasonic parameters such as ultrasonic wave velocity, apparent attenuation, and peak frequencies were analyzed. The elastic modulus of apple was measured by using compression test apparatus. The correlations between ultrasonic parameters and elastic modulus were analyzed. A multiple linear regression model describing the relationship between elastic modulus and ultrasonic parameters was proposed.

• 대한의용생체공학회:의공학회지
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• 제26권2호
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• pp.117-122
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• 2005

The elastic modulus and the apparent density of the trabecular bone were evaluated from spherical indentation tests and Computed Tomography (CT) and their relationship was quantified. The femurs were prepared for trabecular bone analysis. Embedded with respect to their anatomical orientation, the transverse planes of the trabecular bone specimens were scanned at 1㎜ intervals using a CT scanner. The metaphyseal regions of femurs were sectioned with a diamond-blade saw, producing 8㎜ cubes. Using a specially made spherical indentation tester, the cubes were mechanically tested in the anterior-posterior (AP), medial-lateral (ML), and inferior-superior (IS) directions. After determination of modulus from the mechanical testing, the apparent densities of the specimens were measured. The results showed that the IS modulus was significantly greater than both the AP and ML moduli with the AP modulus greater than the ML modulus. This demonstrated that orthogonality was a structural characteristic of the trabecular bone. The power relationship between the modulus and the apparent density was also found to be statistically significant.

• Computers and Concrete
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• 제12권4호
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• pp.377-392
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• 2013

This paper investigates prediction models estimating the hydration properties of concrete, such as the compressive strength, the splitting tensile strength, the elastic modulus,and the autogenous shrinkage. A prediction model is suggested on the basis of an equation that is formulated to predict the compressive strength. Based on the assumption that the apparent activation energy is a characteristic property of concrete, a prediction model for the compressive strength is applied to hydration-related properties. The hydration properties predicted by the model are compared with experimental results, and it is concluded that the prediction model properly estimates the splitting tensile strength, elastic modulus, and autogenous shrinkage as well as the compressive strength of concrete.

• 대한의용생체공학회:의공학회지
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• 제19권2호
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• pp.171-176
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• 1998

본 연구에서는 뼈의 특성을 파악하는 초음파감쇠 파라미터를 재평가하였다. 초음파 속도, 특정 주파수(0.5MHz)에서의 초음파감쇠 및 광역 밴드 초음파감쇠와 같은 초음파 파라미터들을 해면골 입방체 시편의 세 직교방향(전/후, 내/외, 상/하)에서 측정하였다. 그리고 컴퓨터 영상장치를 사용하여 골밀도를 측정했으며, 골 시편의 무게와 부피를 이용하여 외형밀도도 함께얻었다. 이와같이 구해진 외형밀도와 초음파 속도로부터 초음파 탄성영률을 계산하였다. 주파수 0.5MHz에서의 초음파감쇠와 광역밴드감쇠는 골밀도 및 세 직교방향의 초음파 영률과 서로 관련시켜 연관성을 조사하였다. 그 결과 특정 주파수 초음파감쇠가 골밀도 및 탄성영률을 평가하는 능력에 있어서 광역밴드 감쇠보다 우수함을 알 수 있었다. 따라서 광역밴드 초음파감쇠를 측정하여 골의 상태를 평가하는 형행 초음파 진단 기법이 재검토 되어야 하며 본 연구에서 증명된 특정주파수(0.5MHz) 초음파감쇠를 이용하여 골 다공증 진단 예측율을 향상시킬 수 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.173-178
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• 2000

New prediction model is investigated estimating splitting tensile strength and modulus of elasticity with curing temperature and aging. New prediction model is based on the model which was proposed to predict compressive strength, and splitting tensile strength and modulus of elasticity calculated by this model are compared with experimental values. New prediction model well estimated splittinge tensile strength and elastic modulus as well as compressive strength.

• 전자공학회논문지C
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• 제34C권1호
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• pp.12-20
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• 1997

In this paper, we analyze the thermal deformation of mask frame assembly using finite element method(FEM) and predict the beam landing shift during tube operation. For realistic analysis, the apparent thermal conductivity and the apparent elastic modulus are calculated and the shadow mask is modeled as shell without aperatures. Also, all parts inside the tube are modeled and the each radiative effect is considered. Then the finite element analysis is performed for transient thermo-elastic deformation of the mask frame assembly and the beam landing shift is calculated. Experiments are eprformed for 17" cathode ray tube (CRT) to validate the FEM analysis. The temperatures of all parts inside the tube and beam landing shift on the panel are measured and the results are discussed in comparison with the results of the FEM analysis.ysis.