• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.2
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• pp.81-86
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• 2000

For on-shore structures, dynamic analysis becomes increasingly important as the water depth increases and the structural configuration becoines slenderer. In this study, an estimation method for equivalent three dimensional (30) hydrodynamic coefficients is introduced as a part of beam permutation technique development. The beam pemlUtation technique is being developed for obtaining an equivalent beam to a frame structure in order to reduce the degrees of freedom and thus the analysis time significantly. Two 3D structures are used in order to verify the obtained equivalent 3D hydrodynamic coefficients. Two commercial softwares, ANSYS and SACS, are used for the verification. The results of the present analysis are found to be satisfactory in comparison with those by the two softwares.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.2
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• pp.154-159
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• 2013

In this paper, the effect of bolt clamping force and form accuray of contact surface between mirror and mount on mirror surface was studied. Normally, mirror used in reflecting optical system was assembled with mount by bolts or adhesive. In this case, the tension caused by bolt clamping force or adhesive force may distort the mirror surface. Also, form accuracy error of the contact surface have a negative impact on wrenched mirror surface which assembled by bolts or adhesive. In this study, stress and distorted displacements on mirror surface were analyzed according to the different contact surface form accuracies and bolt clamping forces by using the finite element analysis method.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.1-8
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• 2004

In this study, the method of computing and extracting the generalized unsteady aerodynamic matrices using MSC/NASTRAN and MSC/NASTRAN DMAP ALTER has been suggested for the analysis and control of aeroelastic phenomena such as flutter and gust response analysis. In addition to that, the method of approximating the generalized unsteady aerodynamic matrices using minimum state approximation method has been proposed in order to cast the aeroelastic equations of motion in state space form for aeroelastic analysis and control application. Simplified aircraft wing box model has been used for the validation of the methods suggested in this study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.163-171
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• 2006

The behaviors and design procedures of building excavation plane in innovative prestressed support (IPS) system are presented in this paper. Determination procedure for initial pretension in IPS wale subjected to design earth pressure is derived. The computer analysis model under uniform and non-uniform earth pressure is constructed using beam element for the IPS wale, tension-only element for cable, and compression-only element for soil. Axial forces and bending moments of IPS wale under initial pretension and design earth pressure are calculated. The combined stresses due to these axial force and bending moment are calculated and safety condition of building excavation plane is investigated.

• Journal of Korean Society of Steel Construction
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• v.21 no.2
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• pp.183-192
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• 2009

A turn-buckle inserted between tension members sustaining structural loads in the suspension structure system is a device capable of adjusting the tensile force. However, it is difficult to measure the tensile force that is applied to the tension member with the use of a conventional turn-buckle. So a measurable turn-buckle for tensile force measurement has been developed to improve on such a problem. This study focuses on the prevention of a local yielding as well as the maximization of yielding load mentioned in previous studies. A new type of turn-buckle for the measurement to practical use is suggested over the tentative purpose. For this purpose, the ABAQUS analysis of specimens based on theoretical analysis and tests are carried out. The differences among the results of the theoretical analysis, ABAQUS analysis, and the test were insignificant.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.245-255
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• 2001

Existing cut-and-cover tunnels are designed regardless of cut-slope under the assumption that the overburden weight of backfill soil acts on tunnel arch and the earth pressure at rest acts on tunnel walls. However, actual earth pressures acting on the tunnel lining depend on open-cut size composed of cut-slope and cut-width, and thus the tunnel lining shows a different structural behavior. This study investigated the effect of cut-slope on structural behavior of the cut-and-cover tunnel lining as follows; Firstly, a comprehensive numerical analysis method using FLAC2D code was used and verified by field measurements of tunnel profile. Secondly, based on the verified numerical analysis technique, earth pressure acting on the lining, and displacement and sectional force developed on the lining were estimated with various shapes of cut-slopes$30^{\circ}\;, 456{\circ},\; 60^{\circ},\; and\;75^{\circ}%). Numerical analysis results indicate that the steeper cut-slope shows the more displacement and moment of the tunnel lining.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.256-262
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• 2016

This study performed the back-pressure cold forging analysis to minimize the non-forming area of gear teeth for the output hub and reaction hub in automatic transmission. Two important factors of the back-pressure cold forging process, the load of the punch and the backup force applied to the sleeve, were determined through displacement control analysis. The non-forming area of the gear teeth was compared with both cases of the displacement control analysis and load control analysis, and their solution is similar to the measuring result of a real workpiece. The results show that the load of the punch is dependent on the reduction area of the workpiece, and the backup force applied to the sleeve is determined with regard to the cross-section-area of sleeve. This analysis procedure can be useful and effective in determining the manufacturing condition of the back-pressure cold forging process to minimize the non-forming area.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.25-32
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• 2002

In the seismic designing of bridges, the pile foundation of bridge piers generally have been modeled to have a fixed end for its convenience and conservative designing. The fixed-end assumption, however, produces very conservative results in terms of the pier forces. Therefore, many other design methods are evolved to consider the flexibility of the pile foundation. In this study, the response spectrum analysis was performed for a bridge pier having a pile foundation. The shear force, moment, and displacement, which occurred at the pier column under an earthquake loading, were compared to analyze the effects of the modeling method, soil condition and the input earthquake response spectrum. In most cases, the fixed-end model gives larger design forces than flexible foundation models. However, when a long period earthquake is applied to the bridge pier on a soft clay foundation, it is found that the flexible foundation models give larger design forces than the fixed-end model. In the end, the reliability of several flexible foundation models was verified by comparing their results with those of a numerical analysis that considers the soil-structure interaction phenomenon in a rigorous manner.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.240-247
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• 2011

Finite element analysis was undertaken to investigate the effect of freezing force of water unexpectedly penetrated into inserts used in railway sleeper on pullout capacity of anchor bolts for fixing base-plate onto concrete sleeper. Based on the in-situ investigation and measurement of geometry of railway sleeper and rail-fastener, the railway sleeper was modeled by 3D solid elements. Nonlinear and fracture properties for the finite element model were assumed according to CEB-FIP 1990 model code. And the pullout maximum load of anchor bolt obtained from the model developed was compared with experimental pullout maximum load presented by KRRI for verification of the model. Using this model, the effect of position of anchor bolt, amount of fastening force applied to the anchor bolt, and compressive strength of concrete on pull-out capacity of anchor bolts installed in railway sleeper was investigated. As a result, it is found that concrete railway sleepers could be damaged by the pressure due to freezing of water penetrated into inserts. And the pullout capacity of anchor bolt close to center of railway is slightly greater than that of the others.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.59-66
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• 2014

This paper presents the pullout behavior of suction pile using finite difference method; and the commercial software, FLAC3D, was employed for the numerical analyses. The ultimate pullout capacity of suction pile was predicted using conventional equations, and the results were compared with the results from numerical analyses with varying pile diameter, pile length, and the undrained shear strength of clays. Based on the results from 24 analyses, it was found that the failure pattern depends not only on the drainage condition of suction pile, but also on the pile dimensions and the material properties of surrounding soils. The developed side shear (DSS) along the internal surface of the suction pile was collected from numerical analyses, which was used to classify the failure type between sliding failure and tensile failure. Regardless of the external DSS, the high internal DSS tends to result in sliding failure in the numerical analyses, which conforms well to the estimation from conventional equations.