• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.600-604
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• 1997

Knowledge of the complex biomechanical behavior of the human mandible is of great importance in various clinical situations. Various approaches can be used to evaluate the physical behavior of bone. In this study, we developed the voxel mesh program(Bionix) and generated FE models of mandible using Bionix and using handmade work and compared them with free vibration results derived from finite element analysis(FEA). The data of FE models based on DICOM File exported from Computed tomography(CT). Comparing the two models, we found a good correlation about mode type and natural frequency. The voxel based finite element mesh is a valid and accurate method to predict parameters of the complex biomechanical behavior of human mandibles.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.5
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• pp.759-767
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• 2008

Bending deformation of an ionic polymer actuator(IPA) on applied low electric field across its thickness is dominated by electroosmosis of hydrated ions and self-diffusion of free water molecules. In the study by Popovic et al., two processes are assumed to occur sequentially in the way that fast electroosmosis is followed by self-diffusion and finite element formulation for the basic field equations are proposed. However the motions of hydrated ions and water molecules occur at the same time. In this study, those two processes are considered simultaneously and finite element formulation is conducted for the basic field equations governing electrochemical response of an IPA. Some numerical studies for IPA are carried out in order to show the validity of the present formulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.111-111
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• 2004

회전축계는 발전기의 터빈이나 가스터빈 그리고 항공기의 회전익, 선박, 자동차등 산업전반에 널리 사용되어지고 있다. 이러한 회전축계의 안정성 확보와 성능향상을 위해서는 정확한 동적 모델링이 필요하며 지금까지 많은 연구가 되어 왔다. 일반적으로 회전축계의 동특성 이론 모델은 회전관성, 자이로모멘트, 전단변형을 포함하는 티모센코 축 요소를 널리 사용하고 있으며, 많은 연구를 통해 그 유용성이 입증되어 왔다.(중략)

• Geophysics and Geophysical Exploration
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• v.15 no.3
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• pp.121-128
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• 2012

Absorbing boundary conditions are used to mitigate undesired reflections that can arise at the model's truncation boundaries. We apply a complex frequency shifted perfectly matched layer (CFS-PML) to elastic wave modeling in the frequency domain. Modeling results show that the performance of our implementation is superior to other absorbing boundaries. We consider the coefficients of CFS-PML to be optimal when the kinetic energy becomes to the minimum, and propose the modified CFS-PML that has the CFS-PML coefficient ${\alpha}_{max}$ defined as a function of frequency. Results with CFS-PML and modified CFS-PML are significantly improved compared with those of the classical PML technique suffering from large spurious reflections at grazing incidence.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.4
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• pp.363-372
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• 2012

In this study, a new information-based hybrid modeling framework is proposed. In the hybrid framework, a conventional mathematical model is complemented by the informational methods. The basic premise of the proposed hybrid methodology is that not all features of system response are amenable to mathematical modeling, hence considering informational alternatives. This may be because (i) the underlying theory is not available or not sufficiently developed, or (ii) the existing theory is too complex and therefore not suitable for modeling within building frame analysis. The role of informational methods is to model aspects that the mathematical model leaves out. Autoprogressive algorithm and self-learning simulation extract the missing aspects from a system response. In a hybrid framework, experimental data is an integral part of modeling, rather than being used strictly for validation processes. The potential of the hybrid methodology is illustrated through modeling complex hysteretic behavior of beam-to-column connections.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.233-240
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• 1998

In the design of the high-speed railway vehicles of low noise and vibration characteristics, it is desirable to develop efficient and systematic procedures for analyzing large structures. In this paper, some finite-element modelling techniques and an efficient analytical method are proposed for this purpose. The analytical method is based on substructuring approach such as a free-interface method and a generalized synthesis algorithm. In final, the proposed approaches are applied to the finite-element modelling, modal analysis and subsequent model updating procedures of the high-speed railway intermediate trailers.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.6
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• pp.512-519
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• 2013

It is important to understand the vibrating behavior of plate structures for its many engineering applications. In this study, the vibration characteristics of strip plates that have finite width and infinite length are investigated theoretically and numerically. The waveguide finite element(WFE) approach, which is an effective tool for studying waveguide structures, is used in this study. The WFE method requires only a cross-sectional finite element model, and uses theoretical harmonic solutions to assess wave propagation along the longitudinal direction. First, WFE results for a simple strip plate are compared with the theoretical results(i.e., dispersion diagrams and point mobilities) to validate the numerical model. Then, in the numerical analysis, different numbers of longitudinal stiffeners are included in the plate model to investigate the effects of stiffeners in terms of the dispersion curves and mobilities. Finally, the dispersion curves of a stiffened double plate are obtained to examine the characteristics of its wave propagation.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.572-579
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• 2001

Recent industrial requirements for highly precise shape processing have brought the electric discharge machining (EDM) in great need. High precision in EDM is primarily achieved by high performance controllers. However there exists inherent precision loss due to structural deformation. On this background, we study structural deformation characteristics of wire cut EDM via finite element (FE) analysis and axiomatic design. Two different wire cut EDMs are selected as analysis models. 3D CAD package I-Deas is first used to construct FE models of wire cut EDMs, and then ABAQUS FE code is used for following structural analysis. Pertinency of FE mesh refinement is discussed in terms of ${\eta}-factor$. It is shown that performance accuracy of EDM depends strongly on the structural characteristics. Some design enhancements are suggested in an axiomatic design point of view. Finally we provide weight and temperature induced displacement discrepancies between wire end points as position functions of each subframe.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.3
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• pp.191-199
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• 2000

In this paper, a numerical analysis using the finite element method (FEM) is presented which models the eddy current testing (ECT) of tubes with 3-dimensional defects. For the description of 3-dimensional eddy current problems, the governing equation is derived from the Maxwell's equations. The 3-dimensional FEM formulation with hexahedral elements is carried out using the Galerkin weighted residual method. The INCONEL 600 steam generator tube with inner and outer diameter defects is adopted for the numerical analysis, and the ECT signal, which is the trajectory of the probe impedance, is calculated. For the verification of the numerical analysis method, results of numerical calculations and experiments are compared and they show good agreements. Based on this verification, several defect signals are predicted and their characteristics are investigated with the variation in the defect depth and the circumferential angle of the defect.

• The Journal of the Korea Contents Association
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• v.14 no.9
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• pp.343-349
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• 2014

The dental osseointegration implant should be enough to endure occlusion load and it's required to have efficient design and use of implant to disperse the stress into bones properly. Solidworks as a finite element analysis program for modeling and analysis of stress distribution was used for the research. The simple crown model was designed on applying conjoined condition with tightening torque of 20 Ncm of a abutment screw between a cement retained implant abutment and a fixture. A $45^{\circ}$ oblique loading from lingual to buccal side on buccal cusps of crown and performed finite element analysis by 100 N of external load. The results by a analysis for stress distribution of supporting bones of fixture were as below. The von Mises stress was concentrated on the upper side of supporting compact bone regardless of the diameters and lengths of fixture, and the efficiency result of stress reduction was increase of fixture's diameter than it's length. Therefore, it's effective to use wider fixture as possible to the conditions of supporting jaw bone.