• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.459-477
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• 2012

This paper attempts to determine the inclination of the compression strut within variable angle truss models for RC beams loaded in shear-flexure through a proposed semi-analytical approach. A truss unit is used to analyze a reinforced concrete beam, by the principle of virtual work under the truss analogy. The inclination of the compression strut is then theoretically derived. The concrete contribution is addressed by utilizing the compatibility condition within each truss unit. Comparisons are made between the predicted and published experimental results of the seventy one RC beams with respect to the shear strength and the inclined angle of the compression strut at this state to investigate the adequacy of the proposed semi-analytical approach.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.662-670
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• 1999

A numerical prediction was performed to clarify the air motion in the cylinder of an axisymmet-ric four-stroke reciprocating engine at its intake and compression stage. A scheme of finite volume method is used for the calculation. Modified $k-{\varepsilon}$ turbulence model is adopted and wall function is applied to the grids near the wall. The predicted mean velocity and rms velocity profiles showed a reasonable agreement with an available experimental data at its intake and compression stage. The predicted in-cylinder flow fields show that a strong turbulent twin vortex structure is pro-duced during induction but it commences to decay rapidly around inlet valve closure. The mean velocity continues to fall to a low level during compression but the turbulence intensity attains an approximate constant level.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.654-661
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• 1999

This is fundamental study to improve performance of the SI engine,. In this study a conven-tional kerosene engine was modified to LPG dedicated engine which can be operated with LPG(Liquefied Petroleum Gas) The modified model were tested in accordance with various compression ratios. Also the engine performance with modified model was compared with the conventional one. The results are sum-marized as follow; 1. In comparison with the conventional kerosene Gasoline engine and LPG dedicated engine can be operated with lower exhaust emission better fuel economy and better thermal efficiency. 2. But is produce a slightly lower brake horse power.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2323-2333
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• 2021

The paper proposes a technique for reconstructing the true hardening curve of isotropic materials from ring tensile tests. Neutron irradiated 42XNM alloy tensile properties were investigated. The calculation of the true hardening curve for tensile and compression tests of standard cylindrical samples was performed at the first step. After that, the FEM-model was developed and validated using the ring tension and compression tests (with the hardening curve defined in step 1). Finally, the true hardening curve was calculated by selecting the FEM-model parameters and its validation by ring sample tests in different states using an iterative method. For these samples, experimental and calculated gauge length values were obtained, and the corresponding material's constants were estimated.

• Computers and Concrete
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• v.24 no.1
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• pp.51-61
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• 2019

Compressive ability is one of the most important mechanical properties of concrete material. The compressive failure process of concrete is pretty complex with internal tension, shear damage and friction between cracks. To simulate the complex fracture process of concrete at meso level, methodology for meso-structural analysis of concrete specimens is developed; the zero thickness cohesive elements are pre-inserted to simulate the crack initiation and propagation; the constitutive applied in cohesive element is established to describe the mechanism of crack separation, closure and friction behavior between the fracture surfaces. A series of simulations were carried out based on the model proposed in this paper. The results reproduced the main fracture and mechanical feature of concrete under compression condition. The effect of key material parameters, structure size, and aggregate content on the concrete fracture pattern and loading carrying capacities was investigated. It is found that the inner friction coefficient has a significant influence on the compression character of concrete, the compression strength raises linearly with the increase of the inner friction coefficient, and the fracture pattern is sensitive to the mesostructure of concrete.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.06a
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• pp.216-217
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• 2019

Light Field (LF) image can be understood as a set of images captured by a multi-view camera array at the same time. The changes among views can be modeled by a general motion model such as affine motion model. In this paper, we study the impact of affine coding tool of Versatile Video Coding (VVC) on LF image compression. Our experimental results show a small contribution by affine coding tool in overall LF image compression of roughly 0.2% - 0.4%.

• Computers and Concrete
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• v.23 no.6
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• pp.399-408
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• 2019

Structural health monitoring is important for the safety of lives and asset management. In this study, numerical models were developed for the piezoresistive behavior of smart concrete based on finite element (FE) method. Finite element models were calibrated with experimental data collected from compression test. The compression test was performed on smart concrete cube specimens with 75 mm dimensions. Smart concrete was made of cement CEM II 42.5 R, silica fume, fine and coarse crushed limestone aggregates, brass fibers and plasticizer. During the compression test, electrical resistance change and compressive strain measurements were conducted simultaneously. Smart concrete had a strong linear relationship between strain and electrical resistance change due to its piezoresistive function. The piezoresistivity of the smart concrete was modeled by FE method. Twenty-noded solid brick elements were used to model the smart concrete specimens in the finite element platform of Ansys. The numerical results were determined for strain induced resistivity change. The electrical resistivity of simulated smart concrete decreased with applied strain, as found in experimental investigation. The numerical findings are in good agreement with the experimental results.

• Computers and Concrete
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• v.9 no.1
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• pp.21-33
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• 2012

This paper presents the numerical simulation of the rigid 12.6 mm diameter kinetic energy ogive-nosed projectile impact on plain and fiber reinforced concrete (FRC) targets with compressive strengths from 45 to 235 MPa, using a three-dimensional finite element code LS-DYNA. A combined dynamic constitutive model, describing the compressive and tensile damage of concrete, is implemented. A modified Johnson_Holmquist_Cook (MJHC) constitutive relationship and damage model are incorporated to simulate the concrete behavior under compression. A tensile damage model is added to the MJHC model to analyze the dynamic fracture behavior of concrete in tension, due to blast loading. As a consequence, the impact damage in targets made of plain and fiber reinforced concrete with same matrix material under same impact velocities (650 m/s) are obtained. Moreover, the damage distribution of concrete after penetration is procured to compare with the experimental results. Numerical simulations provide a reasonable prediction on concrete damage in both compression and tension.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.644-655
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• 2008

Conventional hyperbolic model does not satisfactorily predict the overall stress-strain behaviors of various geomaterials. Tatsuoka and Shibuya(1992) suggest the generalized hyperbolic equation(GHE) considering strain dependency and calculated performance is in good agreement with precise triaxial compression test results of stress-strain relations over wide range of strains before peak stress condition in some cases, but GHE model also does not satisfactorily predict stress-strain relations as strain goes on state of peak stress in most cases. For improve a weak point of the GHE, in this study, modified form of generalized hyperbolic equation (MGHE model) is proposed which can predict highly nonlinear stress-strain behavior for various geomaterials from small strain to peak stress condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.478-484
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• 2012

In this study, compression analyses of sandwich composites with porous core were carried out. Finite element models of aluminum foam and honeycomb core sandwich composite material were applied solid element. In the case of aluminum foam core, valid equivalence damage model was applied. In the in-plane compression analysis, the maximum load of aluminum foam core sandwich was similar with that of aluminum honeycomb core sandwich. But in case of aluminum honeycomb core sandwich, the load support region becomes longer in comparison with aluminum foam core sandwich. In the out-plane compression analysis, compression maximum load of aluminum honeycomb core sandwich was higher than that of aluminum foam core sandwich. Through these Simulation analysis, obtains the behavior of sandwich composites.