• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.325-332
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• 2005

This paper presents a study on defects in pearlite lamella structure of high carbon steel by means of finite-element method(FEM) simulation. High carbon pearlite steel wire is characterized by its nano-sized microstructure feature of alternation ferrite and cementite. FEM simulation was performed based on a suitable FE model describing the boundary conditions and the exact material behavior. Due to the lamella structure in high carbon pearlite steel wire, material plastic behavior was taken into account on deformation of ferrite and cementite. The effects of many important parameters(reduction in area, semi-die angle, lamella spacing, cementite thickness) on wire drawing process can be predicted by DEFORM-2D. It is possible to obtain the important basic data which can be guaranteed in the ductility of high carbon steel wire by using FEM simulation.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.2
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• pp.103-111
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• 1991

To determine the effects of microstructure on the fatigue crack propagation behavior in SM45C steel, experimental investigations have been carried out with the specimens of different grain sizes and different spacings between the Fe$_{3}$C particles. Fatigue and tensile tests were conducted and the quantitative analysis of the relations between the threshold stress intensity range and grain size, interparticle spacing and yield stress were carried out. Some of the conclusions obtained are as follows; (1) .DELTA.K$_{th}$ was observed to increase with grain size and the spacing between the Fe3C particles. (2) In both pearlite and spheroidite microstructures, .DELTA.K$_{th}$ was increased when yield stress was decreased.sed.

• Computers and Concrete
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• v.9 no.5
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• pp.341-355
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• 2012

Numerical studies are performed to predict the stress-strain behavior of rectangular RC columns confined by multi-spiral hoops under axial and eccentric compressions. Using the commercial finite element package ABAQUS, the Drucker-Prager criterion and the yield surface are adopted for damaged plasticity concrete. The proposed finite element models are compared with the published experimental data. Parametric studies on concrete grades, confinement arrangement, diameter and spacing of hoops and eccentricity of load are followed. Numerical results have shown good agreements with experimental values, and indicated a proper constitutive law and model for concrete. Cross-sectional areas and spacing of the hoops have significant effect on the bearing capacity. It can be concluded that rectangular RC columns confined by multi-spiral hoops show better performance than the conventional ones.

• Structural Monitoring and Maintenance
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• v.7 no.3
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• pp.167-193
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• 2020

In this paper, the behavior of interior steel fiber reinforced concrete beam - column joints (BCJs) under cyclic loading is investigated. An experimental program including tests on twelve reinforced concrete (BCJs) specimens under cyclic loading was carried out. The test specimens are divided into two groups having different geometry: group (G1) (symmetrical BCJs specimens) and group (G2) (nonsymmetrical BCJs specimens). The parameters considered in this study are the steel fibers (SFs) content by volume of concrete (V_f), the spacing of shear reinforcement at the joint region, and the area of longitudinal flexural reinforcement. Test results show that the addition of 0.5% SFs with stirrups spacing S=S_max has effectively enhanced the overall performance of BCJs with respect to energy dissipation, ductility ratio, spreading and width of cracks. The failure of specimens is governed mainly by the formation of a plastic hinge at the face column and outside the beam-column junction. Secondary shear cracks were also observed in the beam-column junctions.

• Journal of Korea Foundry Society
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• v.10 no.6
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• pp.503-508
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• 1990

The effect of interlamellar spacing on tensile behavior and fracture mode at high temperatures has been studied for unidirectionally solidified $Al-CuAl_2$ eutectic composite. The tensile properties at room temperature in $Al-CuAl_2$ eutectic composite improved as the interlamellar spacing decreased due to the constraint effects of closely spaced lamellae, while the opposite behavior was observed at high temperatures due to the annihilation of the constraint effects by phase boundary sliding. The $Al-CuAl_2$ eutectic composite exhibited brittle fracture mode below the temperature at which the reinforcing phase softened but ductile fracture mode above the temperature.

• The Korean Journal of Ecology
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• v.18 no.4
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• pp.512-523
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• 1995

The central theme of Habital heterogeneity is to provide animals with habital complexity or structural diversity and to allow resource partitioning among individuals. In turn, the leads to population stability because prey can escape more easily with more hiding places causing less population fluctuation. Species diversity is characterized due to more potential niches both horizontally and verticall. Empirically, in homogeneous habitats population was less abundant, reproduction and survival were lower, spacing behavior, competition and dispersal were higher than in heterogeneous habitats. The results imply that diversity and conservation of species can be maintained through providing heterogeneous habitats.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.253-260
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• 2000

Pile foundations have been widely used in civil engineering construction for many years. Structures subjected to large lateral loads usually have pile foundations as shallow foundations cannot sometimes support the moments on these structure. The purpose of this paper is to propose the p - multiplier factor (P$\sub$M/) based on the characteristics of behavior of laterally loaded group pile in homogeneous sand. For this, a series of model tests are performed and the composite analytical method proposed by author is used to the propose P$\sub$M/. Based on the model test results of the large number of laterally loaded group piles, p - multiplier factors for homogeneous sand are proposed by back analysis under various condition of soil density, spacing-to-diameter ratio of pile, number of pile, and spacing-to-diameter of pile. P - multiplier approach provides a simple but sufficient tool for characterizing the shadowing group effects of laterally loaded group pile.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.757-764
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• 2004

This paper deals with the numerical study on the displacement behavior of corner areas in an excavation site. Several corner areas always exist in the excavation site. The corner area has two free surfaces, which may become serious weak point from the viewpoint of structural stability. If the structural reinforcements are not applied adequately in corner areas, significant displacement of retaining wall could occur. What is worse, the collapse of retaining system rarely happens. In this paper, 3D numerical analyses were performed to investigate the effect of the arrangement of diagonal and normal strut. From the analysis results, it is found that the spacing between diagonal strut and normal strut should be less than 4m to avoid excessive displacement due to excavation.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.1
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• pp.21-29
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• 2017

Purpose of this study is to investigate structural behavior of the rectangular hollow column with various transverse reinforcement details. Experimental variables are diameter, arrangement details and lateral spacing of cross tie. A total of 66 column specimens have been prepared and tested under axial compressive load. Test results showed that behaviors of column specimens were different depending on the cross tie details. Specimens with cross tie wrapping longitudinal steel and transverse steel have greater strength and ductility than specimens with cross tie wrapping the longitudinal steel.

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1047-1050
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• 2013

Molecular dynamic simulations were performed to examine the wetting behavior of a graphite surface textured with nanoscale pillars. The contact angle of a water droplet on parallelepiped or dome-shaped pillars was investigated by systematically varying the height and width of the pillar and the spacing between pillars. An optimal inter-pillar spacing that gives the highest contact angle was found. The droplet on the dome-covered surface was determined to be more mobile than that on the surface covered with parallelepiped pillars.