• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.311-318
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• 2018

When reinforced concrete structures are exposed to fire, their mechanical properties such as compressive strength, elasticity coefficient and rebar yield strength, are degraded. Therefore, the structure's damage assessment is essential in determining whether to dismantle or augment the structure after a fire. In this study, the confinement effect of lateral reinforcement of RC column according to the numbers of fire exposure face and stirrup was verified by fire resistant test with the heating temperatures of $400^{\circ}C$, $600^{\circ}C$ and $800^{\circ}C$. The test results showed that the peak stress decreases and peak strain increases as the temperature is getting higher, also transverse ties are helpful in improving the compressive resistance of concrete subjected to high temperature. Based on the results of this study, the residual stress of confined concrete under thermal damage is higher at the condition of more lateral reinforcement ratio and less fire exposure faces. The decreasing ratio of elastic modulus of more confined and less exposure faces from the relationship of load and displacement was also smaller than that of opposite conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.1078-1080
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• 2002

The pressure variation of interstitial fluid is one of the most important factors in bone physiology. In order to understand the role of interstitial fluid and the biomechanical interactions between fluid and solid constituents within bone, poroelastic theory was applied. The purpose of this study is to describe the behavior of calf vertebral trabecular bone composed of the porous solid trabeculae and the viscous bone marrow by using a commercial finite element analysis program based on the poroelasticity. In this study, the model was numerically tested for 5 different strain rates, i. e., 0.001, 0.01, 0.1, 1.0, and 10 per second. The material properties of the calf vertebral trabecular bone were utilized from the previous experimental study. Two asymptotic poroelastic response, the drained and undrained deformation, were predicted. From the predicted results for the simulated five strain rate, it was found that the pore pressure generation has a linearly increasing behavior when the strain rate is the highest at 10 per second, other wise it showed a nonlinear the strain rate Increased. Based on the results of the present study, it was suggested that the calf vertebral trabecular bone could be modeled as a porous material and its strain rate dependent material behavior could be predicted.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.759-767
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• 2000

In this study, the time dependent internal stress changes of a Concrete Filled Steel Tube(CFT) column during a fire test were quantitatively analyzed. The strain ratio of a CFT column on the different loads was measured by tensile strength tests in terms of yield strength, tensile strength average extensibility and elasticity modulus. To understand the internal material properties change of concrete in CFT column damaged due to a fire, the compressive strength and elastic modulus tests were measured on a core sample from the center of the steel tube after the fire test. The elastic modulus test measured the strain from the stress. To determine the fire temperature of the test material, a differential thermal analysis was done. From the tested result, the gained data were conducted and an analysis method was suggested. The purpose of this work is to suggest a basic data for structure regulation enactments of the internal fire design of CFT.

• Journal of Korean Society of Steel Construction
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• v.18 no.2
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• pp.225-237
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• 2006

Based on the study conducted by Kim et al. (205a, b), an improved stability design method for evaluating the effective buckling lengths of beam-column members is proposed herein, using system elastic/inelastic buckling analysis and second-order elastic analysis. For this purpose, the stress-strain relationship of a column is inversely formulated from the reference load-carrying capacity proposed in design codes, so as to derive the tangent modulus of a column as a function of the slenderness ratio. The tangent stiffness matrix of a beam-column element is formulated using the so-called "stability functions," and elastic/inelastic buckling analysis Effective buckling lengths are then evaluated by extending the basic concept of a single simply-supported column to the individual members as one component of a whole frame structure. Through numerical examples of several structural systems and loading conditions, the possibilities of enhancement in stability design for frame structures are addressed by comparing their numerical results obtained when the present design method is used with those obtained when conventional stability design methods are used.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.239-240
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• 2007

변압기 코어소재로 사용하는 방향성 규소강판의 가공 방법에 따른 물성을 조사하기 위하여 테이프 와인딩 코어 형태, 곡률반경을 20, 30, 40mm로 하여 토로이달 형태 변압기 시료의 B-H 자성 특성을 조사하였다. 곡률반경이 40mm, 높이는 10mm의 비율에서 보자력은 0.02Oe, 포화자속밀도는 0.98, 1.85T으로 보자력(Hc)은 낮고 포화자속일도(Bs)는 제일 큰 값을 나타내었고, 국내에서 생산되고 있는 방향성 규소강판의 자속밀도값 보다 약간 크게 나타났으며, 본 연구로부터 방향성 규소강판을 이용하여 권자심 코어을 제작할 때 고려해야하는 탄성변형에 대한 중요성과 코어 소재의 가공방법이 자기적 특성에 미치는 영향을 고찰하였다. 또한 토로이달 코어형태의 변압기를 설계 제작시 높이와 곡율반경, 가공 방법에 따라 용량, 효율 등이 다르므로 사전에 소재의 물성을 면밀히 검토 후에 전기기기에 적용해야함을 재확인하였다.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.940-944
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• 2004

This is a thesis about the Solid Coupling Design and Torsional Angular Error Character. The solid coupling which is designed and made is a strong rigidity material. This is a experiment of Solid Coupling Torsional Error. The Angular Error, FEM and Circularity Measurement. Devices are Twist Friction Driver, Polygon, Autocollimator and Standard Encoder for Measurement. Coupling caused by elastic deformation causes angular error.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.194-197
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• 1999

고분자 복합재료는 금속에 비하여 경량, 고강도, 고탄성율 등의 장점을 가지고 있어 여러 산업에서 기존의 금속 재료를 대체할 수 있는 재료로서 그 사용이 점차 증가하고 있다[1-5]. 특히 사회적으로 환경 문제가 대두되면서 열가소성 복합재료에 대한 관심이 높아지고 있으며 이에 대한 연구가 더욱 요구되고 있다. (중략)

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.159-164
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• 2000

The fracture behaviors of aluminum foils and sheet papers were analyzed on the basis of linear elastic fracture mechanics(LEFM). The fracture loads of the similarly shaped specimens were calculated by dimensional analysis. The actual fracture loads were measured using the simple tension equipment. The predicted fracture loads were compared with the experimental results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1341-1350
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• 1992

This paper addresses the practical problem of finding a useful strain energy function of the incompressible rubberlike materials. It examines methods by which the form of the functions are determined and shows how the selection of experimental data influences the resulting form of the functions. From this information, an optimal choice of the form of energy functions becomes possible. Phenomenological theories used in this paper are limited to elastic, incompressible material models. Due to the nature of the phenomenological methods, these theories are accurate only for the materials treated. However, they serve as a starting basis for the study of more complicated material behaviors.

• Korean Journal of Agricultural Science
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• v.12 no.2
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• pp.309-323
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• 1985

The Paper describes the observed behaviour in the undrained triaxial condition of marine clays remoulded at various different levels of factors, to find out the effects of restricted factors on the stress-strain characteristics. The conventional triaxial compression tests $({\sigma}1>{\sigma}2={\sigma}3)$ were carried out on the 50mm in diameter and 100mm long cylindrical specimens of Gun-san bay mud under controlled various moisture content, density, axial strain rate and passing on No. 200 sieve. Significant conclusions from this study are; 1. The compressible deviator stress at failure of pure marine clay was observed to increase with the decrease of moulding moisture content. 2. The compressible deviator stress at failure increased with the increasing of moulding dry density. 3. The interaction between moisture content and density on the stress-strain characteristics of marine clay was remarkedly significant, as the result of factorial experimental method. 4. The effect of axial strain rate on stress-strain behaviour was unsignificant in marine clay and but the secant moduli could be pronounced on a slight decreasing with increase of the strain rate. 5. With the increasing of the passing on No. 200 sieve, the deviator stress increased regularly. 6. The multiple regression equation could be modeled for the prediction of stress or strain and the comparison with experimental results relatively proved the accuracy.