• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6C
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• pp.313-319
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• 2009

In this study, field pull-out test and 3-D FEM analysis have been performed for examining and reflecting the behavior of steel pipe nailing installed foldable wedge. Field pull-out test was performed under various conditions. As a result, the steel pipe nailing installed foldable wedge has an effect of pull-out resistance increased about 30% in comparison with non-wedge type steel pipe nailing. Through back analysis in 3-D FEM for behavior of non-wedge type steel pipe nailing, friction characteristics between nail to soil was analyzed and obtained first consistent with field pull-out behavior. Then, the frictional characteristic was used for analyzing the behavior of the steel pipe nailing installed foldable wedge. The result was compared with the test results. Consequently, friction coefficient (${\mu}$) of about 1.2 between grout to soil leads to good agreement with analysis results and test results. And a limited pull-out resistance, $$T_L{\sim_=}32$$ tonf is similar to field pull-out test result which is improved about 33% in comparison with non-wedge type steel pipe nailing's $$T_L{\sim_=}24$$ tonf.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.371-379
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• 2000

The 4-pole linear homopolar synchronous motor (LHSM), so called linear inductor motor, is composed of the figure-of-eight shaped 3-phase armature windings, DC field windings, and the segmented secondary with the transverse bar track. To reduce the calculation time, the simplified 3D finite element model with equivalent reluctance and/or permanent magnet is presented. To obtain a clear understanding, propriety and usefulness of the developed model, we compare with the results of simplified 3D FEA, general 3D FEA and test. Consequently, the results of simplified and 3D FEM analysis are nearly identical, but much larger than that of static test at d-axis armature excitation. Therefore the improved FEA model, such as full model with half slot, is needed for the precise analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.477-482
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• 2017

When using the FDM to create a 3D object, a thermoplastic filament is heated to its melting point and then extruded layer by layer. Although the FDM printing process has many advantages, its accuracy, and surface finish are not satisfactory. In recent years, much research has been devoted to improving the accuracy of the FDM printing process. The temperature difference between the nozzle and the interior of the chamber of a 3D printer is one of the important parameters affecting the printing process. In this study, we propose a methodology to reduce this temperature difference through design improvement. In addition, we elucidate how this design improvement affects product quality. The FDM printing process is conventionally carried out in a closed chamber. However, in this study, an open heating system is used to reduce the temperature. The FDM printing processes were simulated using FEM analysis.

• Transactions of Materials Processing
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• v.10 no.1
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• pp.23-29
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• 2001

In this study, the optimized initial hole shape for T-branch forming was proposed to obtain effective welding region. Design variables were determined by approximation analysis using volume constant condition. We performed 3D elastic-plastic FEM(Finite Element Method) analysis to simulate T-branch forming process. The variation of height and thickness of T-branch with various hole shapes was investigated. The optimized initial hole shape equation was obtained by using results for the numerical analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.03a
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• pp.97-102
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• 1997

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.1
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• pp.6-11
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• 2004

The single phase switched reluctance motor (SRM) has many merits; simple structure and driving circuits, easy operation and speed control, and etc. This paper presents the torque characteristics of disk type single phase SRM by changing the salient pole lengths and pole arcs. The prototype single phase SRM has a three dimensional magnetic flux pattern because of its structure. That is, the radial and axial magnetic flux contributes to torque generation. Thus, 3D analysis is required for computation of its magnetic field. In this paper, 3D FEM is used for analyzing the magnetic flux distribution and magnetic co-energy.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.11
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• pp.612-615
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• 2002

The main advantages of Disk type Single-Phase Switched Reluctance Motor (DSPSRM) is the simple construction, rugged structure, low manufacturing cost and simple driving circuit. It is especially possible to make the short axial length of DSPSRM. Therefore, it is suitable to setup this motor in a narrow space. This paper presents the shape design to maximize the average torque of DSPSRM that is achieved by 3D Finite Element Method (3D FEM) considering the nonlinear of magnetic material. The characteristics of two different rotor shapes are compared. The design parameters, such as the rotor and stator pole arc, are selected to the parametric study. The effect of pole arc ratios on the torque performance is investigated. From these results, the optimal pole arc to produce the maximum torque is determined.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.575-576
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• 2007

• Interaction and multiscale mechanics
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• v.6 no.2
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• pp.237-255
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• 2013

In this paper, a meshfree-enriched finite element method (ME-FEM) is introduced for the large deformation analysis of nonlinear path-dependent problems involving contact. In linear ME-FEM, the element formulation is established by introducing a meshfree convex approximation into the linear triangular element in 2D and linear tetrahedron element in 3D along with an enriched meshfree node. In nonlinear formulation, the area-weighted smoothing scheme for deformation gradient is then developed in conjunction with the meshfree-enriched element interpolation functions to yield a discrete divergence-free property at the integration points, which is essential to enhance the stress calculation in the stage of plastic deformation. A modified variational formulation using the smoothed deformation gradient is developed for path-dependent material analysis. In the industrial metal forming problems, the mortar contact algorithm is implemented in the explicit formulation. Since the meshfree-enriched element shape functions are constructed using the meshfree convex approximation, they pose the desired Kronecker-delta property at the element edge thus requires no special treatments in the enforcement of essential boundary condition as well as the contact conditions. As a result, this approach can be easily incorporated into a conventional displacement-based finite element code. Two elasto-plastic problems are studied and the numerical results indicated that ME-FEM is capable of delivering a volumetric locking-free and pressure oscillation-free solutions for the large deformation problems in metal forming analysis.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.122-129
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• 2005

On the cluster system, the parallel code of rigid-plastic FEM has been developed. The cluster system, Simforge, has 15 processors and the total memory is 4.5GBytes. In the developed parallel code, the distributed data of the column-wise partitioned stiffness are stored as the compressed row storage and the diagonal preconditioned conjugate gradient solver is applied. The analysis of block upsetting is performed with the parallel code on Simforge cluster system. In this paper, the analysis results are compared and discussed.