• Progress in Superconductivity
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• v.13 no.3
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• pp.151-157
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• 2012

In this paper, we used E-J constitutive law and H-formulation to calculate magnetic field profile, current density, and magnetization of high temperature superconductor (HTS) placed in time varying applied magnetic field. Finite element method (FEM)-based software, Comsol Multiphysics 3.5a, was employed to simulate 2-dimensional model of a superconducting thin strip. The numerical results based on Kim's critical state model were compared with the case of strip in a perpendicular field in the Brandt's paper as well as experimental data observed by Scanning Hall Probe and SQUID.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4469-4474
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• 2014

This paper proposes a novel analysis method on the driving performance of LIM (linear induction motor) by FEM (finite element method). First, a linear model was converted with a rotation model to perform the dynamic analysis for a long time. Through the FEM model, the slip parameter for the control algorithm could be induced effectively. The LIM for the traction system was performed at a constant V/f in the region of constant torque, and a constant V and variable f in the region of constant power. Several slip characteristic curves according to the voltage and frequency were calculated by FEM in advance. The driving performance was then induced by interpolating the slip characteristic curves according to the load of the vehicle.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.542-552
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• 2019

The strength assessment is the most important part at the design of ice-class propeller. Based on ice rules for ice-class propeller in IACS URI3 and FEM, the strength assessment method of ice-class propeller is established in this paper. To avoid the multifarious meshing process of propeller blade, an automatic meshing method has been developed by dividing the propeller geometry into a number of 8-node hexahedron elements along radial, chordwise and thickness directions, then the loaded areas in five cases can easily be calculated and identified. The static FEM is applied to calculate the stress and deformation of propeller blade. The fair agreements between the results of the present method and ANSYS/Workbench demonstrate its robust and the feasibility, and also the method is able to produce smooth gradient field. The blade stress and deformation distributions for five load cases are studied, and then the strength of the whole blade is checked.

• Structural Engineering and Mechanics
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• v.57 no.5
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• pp.861-876
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• 2016

The determination of the critical buckling load of multistory structures is important since this load is used in second order analysis. It is more realistic to determine the critical buckling load of multistory structures using the whole system instead of independent elements. In this study, a method is proposed for designating the system critical buckling load of torsion-free structures of which the load-bearing system consists of frames and shear walls. In the method presented, the multistory structure is modeled in accordance with the continuous system calculation model and the differential equation governing the stability case is solved using the differential transform method (DTM). At the end of the study, an example problem is solved to show the conformity of the presented method with the finite elements method (FEM).

• Steel and Composite Structures
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• v.47 no.1
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• pp.37-50
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• 2023

This paper presented an investigation into steel tubes encased high-strength concrete (STHC) composite walls, wherein steel tubes were embedded at the boundary elements of high-strength concrete walls. A series of cyclic loading tests was conducted to evaluate the failure pattern, hysteresis characteristics, load-bearing capacity, deformability, and strain distribution of STHC composite walls. The test results demonstrated that the bearing capacity and ductility of the STHC composite walls improved with the embedding of steel tubes at the boundary elements. An analytical method was then established to predict the flexural bearing capacity of the STHC composite walls, and the calculated results agreed well with the experimental values, with errors of less than 10%. Finally, a finite element modeling (FEM) was developed via the OpenSees program to analyze the mechanical performance of the STHC composite wall. The FEM was validated through test results; additionally, the influences of the axial load ratio, steel tube strength, and shear-span ratio on the mechanical properties of STHC composite walls were comprehensively investigated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.288-297
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• 1990

The method of analyzing flexible mechanisms with clearances was studied considering flexibility of beams in the mechanism using finite elements. Both ends of a beam were modeled as free following Dubowsky's impact pair model. Instead some force constraints were imposed at imposed at the connections between adjoining links. Coulomb model has been developed using dry frictions in place of tangential damping forces in the impact pair model and the contact compliance and damping coefficient approximated in a form of root function were used. As examples, impacts of a rigid ball in a cylinder, impact beam model and four-bar mechanisms made up of three flexible links with clearance connections were simulated numerically. The results from examples showed similar but a little bit smaller magnitude of impact forces compared with published studies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1882-1887
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• 2002

This study is to develop a automatic design program of mechanical elements as the integrated system which can create automatically 3-dimensional solid and surface model using visualLISP. By the applying developed system to CAE system, the following objects are realized. At first, constructing the library of automatic design program for unexperienced design engineer, the 3-dimensional modeling of mechanical elements can be obtained easily. at second, the 3-dimensional model for ratchet wheel design is created by finete element model of CAE system and the optimal design condition of key way.

• Structural Engineering and Mechanics
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• v.29 no.5
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• pp.531-550
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• 2008

This paper adopts the numerical assembly method (NAM) to determine the exact solutions of natural frequencies and mode shapes of a multi-span and multi-step beam carrying a number of various concentrated elements including point masses, rotary inertias, linear springs, rotational springs and springmass systems. First, the coefficient matrix for an intermediate station with various concentrated elements, cross-section change and/or pinned support and the ones for the left-end and right-end supports of a beam are derived. Next, the overall coefficient matrix for the entire beam is obtained using the numerical assembly technique of the conventional finite element method (FEM). Finally, the exact solutions for the natural frequencies of the vibrating system are determined by equating the determinant of the last overall coefficient matrix to zero and the associated mode shapes are obtained by substituting the corresponding values of integration constants into the associated eigenfunctions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.10
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• pp.990-998
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• 2004

There have been lots of efforts to analyze the dynamic characteristics of mechanical systems. However, it is difficult the know the dynamic characteristics of mechanical systems composed of many parts with joints. Specially, in case of a bolted Joint structure, no effective modeling method has been defined to acquire dynamic characteristics of the structure using the finite element (FE) analysis. In this research, a linear dynamic model is developed for bolted feints and large interfaces using con frusta method and linear spring elements, respectively. The developed modeling method for bolted joints is verified based on the experimental result.

• Structural Engineering and Mechanics
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• v.50 no.4
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• pp.441-457
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• 2014

This paper presents a finite element based numerical model to solve two dimensional bi-material problems. A bi-material beam consisting of two phase materials ceramic and metal is modelled by finite element method. The beam is subjected simultaneously to mechanical and thermal loadings. The main objective of this study is the analysis of crack deviation located in the brittle material near the interface. The effect of temperature gradient, the residual stresses and applied loads on crack initiation, propagation and deviation are examined and highlighted.