• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.05a
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• pp.89-97
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• 1998

In this study, under large scale yielding conditions crack propagation is found to governed by parameters based on the J-integral or on the crack opening displacement. But initiation of crack propagation of ductile material seems to be controlled by just on parameter that is the strain. The relationship between the critical value of J-integral and the local fracture strain in uniaxial tensile test in the region of maximum reduction in area. Therefore, the fundamental theorectical equation by the proposed elastic-plastic fracture toughness and the local fracture strain has a merit. in comparison with the ASTM method, which can measure by using the load-displacement curve and the specimens in tenslie test.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.25-33
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• 1998

In this study, under large scale yielding conditions crack propagation is found to governed by parameters based on the J-integral or on the crack opening displacement. But initiation of crack propagation of ductile material seems to be controlled by just on parameter that is the strain. The relationship between the critical value of J-integral and the local fracture strain in uniaxial tensile test in the region of maximum reduction in area. Therefore, the fundamental theoretical equation by the proposed elastic-plastic fracture toughness and the local fracture strain has a merit, in comparison with the ASTM method, which can measure by using the load-displacement curve and the specimens in tensile test.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.475-480
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• 2003

Latex modification of concrete provides the material with higher flexural strength. This increase in flexural strength can attribute to the crack-arresting action of polymer in concrete, and also to the bonding they provide between the matrix and aggregates. This experimental study presents the fracture behavior of 12 flexural reinforced concrete beams repaired or strengthened by latex-modified concrete with the main experimental variables such as overlay thickness, strength thickness, and shear reinforcement. The results are as follow: All beam specimens having shear reinforcement were failed by delamination rupture at concrete interface at about 80% of ultimate loading after flexural cracking. All specimens overlayed and strengthened by latex-modified concrete (LMC) showed higher ultimate flexural strength than OPC control specimen, but lower than LMC control specimen. This increase in flexural strength could attribute to the high bonding they provide between the matrix and aggregates. All specimens except two shear unreinforced showed quite similar and consistent displacement behavior. The effect of overlay and strength thickness on the load-displacement relationship were a small at this study.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.263-265
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• 2015

In this paper, a coil spring of the suspension components of the car is calculated through FEM(Finite Element Method) when a portion of the one is applied by an external load. we analyze the situation by using 'Large Deformation Analysis SW' in the EDISON structural dynamics server. Results of the analysis are about a displacement of the upper spring after deformation and total mass, and we use them to calculate the spring constant and maximum von-Mises stress by using Hooke's law and von-Mises stress equation. Finally, we visualize the relationship between the calculated spring constant and the mass through graphs and this data are beneficial for industries related to the spring.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.2
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• pp.28-33
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• 2003

This study is performed to evaluate and design the dynamic characteristics of the onboard machinery with resilient mounts. To avoid resonance with onboard machinery and external force, it is necessary to calculate natural frequencies of the resilient mounting system more accurately. Natural frequencies of on board machinery are determined by rigid body properties(mass, moment of inertia, center of mass) of machinery and stiffness of mounts. But it is very difficult to calculate rigid body properties theoretically. And stiffness properties of rubber mounts vary with dynamic displacement, pre load, frequency and temperature, and so on. In this study, we have identified rigid body properties using experimental modal analysis and estimated dynamic stiffness of rubber mount for onboard machinery using measured vibration response during seatrial. We measured displacement excitation through deck under mounts and evaluated relationship between modes of resilient mounting system and main excitation sources of a ship.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.9
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• pp.903-909
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• 2007

A fatigue capsule is one of the special capsules to investigate the fatigue characteristics of the nuclear materials during an irradiation test in a research reactor, HANARO. In this study, the performance test and the preliminary fatigue test results by using a cyclic load device newly developed for a fatigue capsule are described. In order to obtain the characteristics such as a realization and a controllability of the periodic wave shape and the relationship between the pressure and the load, a spring and rigid bar specimens are used. The fatigue test for the 316L stainless steel specimen with 1.8mm in diameter and 12.5mm in gage length is also performed under the same conditions as the temperature($550^{\circ}C$) of the specimen during irradiation tests. As a result of the test, the fracture of the specimen occurs at a total of 70,120 cycles(about 12 days), and the displacement in this case is 2.02 mm. It is expected that these results will be used for determining test conditions and a comparison of the in-pile fatigue test results.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.69-75
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• 2008

Shear tests were carried out on interface between two concrete eco-blocks which comprise segmental retaining wall. Three interface conditions were considered : 1) direct contact of two blocks, 2) placing rubber pad between two blocks, 3) placing rubber pad and shear key between two blocks. According to shear tests, shear load-shear displacement relationship which was obtained from direct contact of two blocks was similar to elastic-perfectly plastic behavior. Ductile behavior of shear load-shear displacement relationship was observed for the interface condition of placing rubber pad. Apparent minimum shear capacities and apparent friction angles for the interface conditions of direct contact of two blocks, placing rubber pad between two blocks, placing rubber pad and shear key were 1.7 kN/m, $27.6^{\circ}$ and 4.2 kN/m, $26.2^{\circ}$ and 20.9 kN/m, $26.0^{\circ}$ respectively.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.3
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• pp.175-181
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• 2020

For the success of a structural integrity management, it is essential to acquire structural response data at some critical locations with limited number of sensors. In this study, the structural response of numerical model was estimated by data fusion approach based on the Kalman filter known as stochastic recursive filter. Firstly, transient direct analysis was conducted to calculate the acceleration and strain of the numerical standing beam model, then the noise signals were mixed to generate the numerical measurement signals. The acceleration measurement signal was provided to the Kalman filter as an information on the external load, and the displacement measurement, which was transformed from the strain measurement by using strain-displacement conversion relationship, was provided into the Kalman filter as an observation information. Finally, the Kalman filter estimated the displacement by combining both displacements calculated from each numerically measured signal, then the estimated results were compared with the results of the transient direct analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.805-810
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• 2002

An experimental study was carried out to evaluate the structural performance of new retrofitting technology using high performance carbon fiber bar and strengthening metal fittings. Experimental programs were accomplished to evaluate the structural performance of test specimens, such as load-displacement relationship, crack propagation, ductility, and strain of retrofitting materials etc.. Specimens(BCR2, BCR2-AF1) designed with the new retrofitting technology using high-performance carbon fiber bar and strengthening metal fittings showed much higher load-carrying capacity and ductility compared to specimens(BC1P, BC2P, BS30) designed with the conventional retrofitting method.

• Structural Engineering and Mechanics
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• v.34 no.3
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• pp.301-317
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• 2010

This paper studies the reliability of an analytical tool for predicting the lateral load-deformation response of RC columns while subjected to lateral cyclic displacements and axial load. The analytical tool in this study is based on a fiber element model implemented into the program DRAIN-2DX (fiber element). The response of RC column under cyclic displacement is defined by the behavior of concrete, and reinforcing steel under general reversed-cyclic loading. A tri-linear stress-strain relationship for the cyclic behavior of steel is proposed and the improvement in the analytical results is studied. This study only considers the behavior of columns with flexural dominant mode of failure. It is concluded that with the implementation of appropriate constitutive material models, the described analytical tools can predict the response of the columns with reasonable accuracy when compared to experimental data.