• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.206-211
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• 1993

The explicit scheme for finite element analysis of sheet metal forming problems has been widely used for providing practical solution since it improves the convergency problem,memory size and computational time especially for the case of complicated geometry and large element number. In the present work, a basic formulation for rigid-plastic explicit finite element analysis of plain strain sheet metal forming problems has been proposed. The effect of some basic parameters involved in the dynamic analysis has been studied in detail. A direct trial-and-error method is introduced to treat contact and friction. In order to show the validity and effectiveness of the proposed explicit scheme, computation are carried out for cylindrical punch stretching and the computational results are compared with those by the implicit scheme as well as with a commercial code. The proposed rigid-plastic explicit element method can be used as a robust and efficient computational method for analysis of sheet method forming.

• Tunnel and Underground Space
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• v.14 no.6 s.53
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• pp.423-428
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• 2004

The stability of tunnels is usually analyzed as plain strain condition and rock bolts are assumed as 2 dimensional equivalent continuum structures. In this study, 2 and 3 dimensional numerical analyses were conducted to verify the validity of 2 dimensional analysis of rock bolts. Since the results of 2 dimensional analysis showed more than $10\%$ differences in poor rocks, it seems that 3 dimensional analysis is required in poor rocks.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.133-138
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• 1998

The purpose of this study is to offer basic information of fly ash concrete for field application. Through before study and fly ash in mortar, various properties as fly ash ratio in concrete were checked according to the experimental result, slump was increased and entrained air quantity was decreased as fly ash ratio is increased in fresh concrete. In hardened concrete, strength development of plain concrete(W/B 50%) was slower than water-reduced concrete(W/B 40%) at early age. Especially water-reduced concrete was remarkabily faster than no fly ash in concrete. Moduls of stastic elasticity and stress-strain relationship of fly ash in concrete nearly were effect on no fly ash concrete.

• Structural Engineering and Mechanics
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• v.23 no.6
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• pp.713-737
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• 2006

This paper presents the results of an experimental investigation on the behaviour of 56 reinforced concrete beams subjected to pure torsion. The reported results include the behaviour curves, the failure modes and the values of the pre-cracking torsional stiffness, the cracking and ultimate torsional moments and the corresponding twists. The influence of the volume of stirrups, the height to width ratios and the arrangement of longitudinal bars on the torsional behaviour is discussed. In order to describe the entire torsional behaviour of the tested beams, the combination of two different analytical models is used. The prediction of the elastic till the first cracking part is achieved using a smeared crack analysis for plain concrete in torsion, whereas for the description of the post-cracking response the softened truss model is used. A simple modification to the softened truss model to include the effect of confinement is also attempted. Calculated torsional behaviour of the tested beams and 21 beams available in the literature are compared with the experimental ones and a very good agreement is observed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.3
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• pp.464-471
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• 2003

Among various methods to acquire high strength in plain carbon steel, the mettled of grain refinement by controlling thermo-mechanical processing parameters has gained a great attention if steel rolling industries. In the present study, three different rolling pass schedules are proposed to obtain fine grains which are based on combined results of recrystallization modelling, finite element analysis and experiment. Since meta-dynamic or dynamic recrystallization has been found to be very effective in producing fine grains, reduction ratio and interpass time in the proposed rolling pass schedules were determined in order to invoke such recrystallization as often as possible.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.106-113
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• 2002

In this study, a numerical analysis method for soil-pile interaction in frequency domain problem is presented. The total soil-pile interaction system is divided into two parts so called near field and far field. In the near field, beam elements are used for a pile and plain strain finite elements for soil. In the far field, dynamic fundamental solution for multi-layered half planes based on boundary element formulation is adopted for soil. These two fields are coupled using FE-BE coupling technique In order to verify the proposed soil-pile interaction analysis, the dynamic responses of pile on multi-layered half planes are simulated and the results are compared with the experimental results. Also, the dynamic response analyses of interface spring elements are performed. As a result, less spring stiffness makes the natural frequency decrease and the resonant amplitude increase.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.4
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• pp.33-40
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• 2006

In present study, the principal stress condition needed to conduct cubical large-scale triaxial test which can reflect three dimensional stress condition (or plain strain condition) in a dam was investigated by performing model test and numerical analysis and the principal stress ratio varying with the height of CFRD was examined. Also, the principal stress ratio in CFRD body was investigated from the monitoring results of horizontal and vertical earth pressure gages, installed in the center zone and lower part of transition zone of the dam body, respectively, in order to consider the principal stress condition in the large-scale triaxial test to model the behavior of CFRD. The result of the study indicated that the principal stress ratio decreased gradually from the lower to the upper part in the dam body for its center axis and was about 0.5 and 0.2 in the lower and upper part, respectively.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1317-1323
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• 2009

A finite element analysis was performed for new earth retention system that is a kind of truss tower with non-supported excavation. A 2D finite element model was adopted in this study to investigate the behavior of the earth retention system. Just because this non-supported truss tower system is too complex to model in 2D plain-strain condition to itself, so have to simplify it by the conception of equivalent rigidity. The horizontal displacement of the wall and lateral earth pressure distribution on the wall were computed. And it is compared with NAVFAC design manual.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.314-319
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• 2004

High temperature fracture toughness characteristics of shot peened spring steel(SUP-9), which is used for automobile suspension system and railroad, was investigated in this paper. Fracture tougness test for room temperature, $100^{\circ}C$ , and $200^{\circ}C$ were evaluated by material test system(MTS). The experimental results show that the fracture toughness was improved by peened and unpeened. The fracture toughness for high temperature were also improved by peened and unpeened.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.57-62
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• 1990

This paper is to study the effect of rectilinear confinement in high-strength concrete subjected to a monotonically increasing compressive axial loads. To investigate behavior of columns rectilinearly confined with lateral ties and longitudinal rebars, twelve specimens including two plain concrete specimens were tested. The main variables in this study are volumetric ratio of lateral ties, cistribution of lateral ties, yield strength of logitudinal steel, ratio of area of longitudinal steel to the area of cross section. The test results were not only compared with an empirical model for the stress-strain curve of rectilinearly confined high-strength concrete but also the existing model. The empirical model used calculating column capacity shows better agreement with the test results tham the existing model.