• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.271-272
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• 2008

This paper is concerned with the prediction of micro structural changes of pearlitic steel wire during clod drawing. The most important microstructural aspects are ferrite/cementite interlamellar spacing, cementite shape and thickness, since those are crucial factors to determine the mechanical strength of pearlitic steel. In this study, a couple of new algorithms to predict the above microstructural changes are developed based on the deformation histories of macro material points obtained from finite element simulations for pearlitic steel wire drawing. Some predictions are shown. The special features of the algorithms developed in this study are discussed in details.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.3
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• pp.267-271
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• 2005

This paper deals with two kinds of novel shape switched reluctance motors (SRM) with magnetic barriers in order to improve operating performances of prototype. The magnetic barriers make rotor poles more saturated, and consequently inductance profiles are distorted. The changed inductance affects input current shape and eventually torque characteristics. In order to analyze the complicated flux pattern of the SRM with magnetic barriers and its terminal characteristics simultaneously, coupled field circuit modeling method is used. The finite element method is used to model the nonlinear magnetic field, and coupled to the circuit model of the SRM overall system. After experimental results are presented to prove the accuracy of the method, the several analysis results are compared, and the improved rotor shape is presented.

• Structural Engineering and Mechanics
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• v.6 no.7
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• pp.757-772
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• 1998

The objective of the present work is to estimate the strength and failure characteristics of symmetric thin square laminates under negative shear load. Two progressive failure analyses, one using the Hashin criterion and the other using a Tensor polynomial criterion, are used in conjunction with the finite element method. First-order shear-deformation theory along with geometric nonlinearity in the von Karman sense has been incorporated in the finite element modeling. Failure loads, associated maximum transverse displacements, locations and modes of failure including the onset of delamination are discussed in detail; these are found to be quite different from those for the positive sheer load reported in Part I of this study (Singh et al. 1998).

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.271-288
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• 1991

SMAP-S2 is an advanced too-dimensional , static finite element computer program developed for the geometric and material nonlinear structure-medium interaction analysis. The program has specific applications for modeling geomechanical problems associated with multi-staged excavation or embankment. Theoretical formulations and computational algorithms are presented along with the description of elasto-plastic material models. Nonlinear features of the code are verified by comparing with known solutions or experimental test results. Capabilities of per- and post-processing programs are discussed.

• Journal of ILASS-Korea
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• v.25 no.3
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• pp.119-125
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• 2020

In this paper, we used Helmholtz solver based on 3D finite element method to quantitatively analyze the effects of change of gain, time delay and time delay spread, which are the main variables of flame transfer function, on combustion instability in gas turbine combustor. The effects of the variable of flame transfer function on the frequency and growth rate, which are the main results of combustion instability, were analyzed by applying the conventional heat release fluctuation model and modified one considering the time spread. The analysis results showed that the change of gain and time delay in the same resonance mode affected the frequency of the given resonance modes as well as growth rate of the feedback instability, however, the effect of time delay spread was not relatively remarkable, compared with the dominant effect of time delay.

• Architectural research
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• v.12 no.2
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• pp.93-98
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• 2010

This paper describes a numerical method for estimating the elastic moduli of cement paste. The cement paste is modeled as a unit cell which consists of three components: the unhydrated cement grain, the gel, and the capillary pore. In the unit cell, the volume fractions of the constituents are quantified using a single kinetic function calculating the degree of hydration. The elastic moduli of cement paste are calculated from the total displacements of constituents when a uniform pressure is applied to the gel contact area. The cement paste is assumed to be a homogenous isotropic matrix. Numerical simulations were conducted through the finite element analysis of the three-dimensional periodic unit cell. The model predictions are compared with experimental results. The predicted trends are in good agreement with experimental observations. This approach and some of the results might also be relevant for other technical applications.

• Advances in Computational Design
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• v.2 no.1
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• pp.57-69
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• 2017

The composite plate to upgrade structures and, in particular, to extend the lives of reinforced concrete beams has wide applications. One of the main aspects of the bonded strengthening technology is the stress analysis of the reinforced structure. In particular, reliable evaluation of the adhesive shear stress and of the stress in the composite plates is mandatory in order to predict the beam's failure load. In this paper, a finite element analysis is presented to calculate the stresses in the reinforced beam under mechanical loads. The numerical results was compared with the analytical approach, and a parametric study was carried out to show how the maximum stresses have been influenced by the material and geometry parameters of the composite beam.

• Advances in Computational Design
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• v.2 no.1
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• pp.29-42
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• 2017

This study presents algorithms for determining the fuzzy critical loads of planar steel frame structures with fixity factors of beam - column and column - base connections are modeled as triangular fuzzy numbers. The finite element method with linear elastic semi-rigid connection and Response Surface Method (RSM) in mathematical statistic are applied for problems with symmetric triangular fuzzy numbers. The ${\alpha}$ - level optimization using the Differential Evolution (DE) involving integrated finite element modeling is proposed to apply for problems with any triangular fuzzy numbers. The advantage of the proposed methodologies is demonstrated through some example problems relating to for the twenty - story, four - bay planar steel frames.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1539-1544
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• 1995

Copper blow test to measure the forging capability of 35 ton counterblow hammer and upset of plasticine on the model hammer to investigate the change of the blow efficiency during the forging process have been performed together with finite element analyses of these experiments. The blow efficiency of the hammer has been found to be dependent on the friction and on the contact area between the die and the workpiece. The effects of the volume and the aspect ratio of the billet have not been found. Inferring from the experimental results and Schey's empirical formula on the forging load, we expect that the efficiency also varies with the flow stress of the workpiece material and with the shape complexity of the forging product.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.121-131
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• 1998

This paper applies the FE analysis procedure, developed in the Part I of the companion article, to the three-dimensional rubber pad deformation during rubber-pad forming process. Effects of different algorithms corresponding to incompressibility constraint and time integration methods on numerical solution responses are investigated. Laboratory scale experiments support the validity of the developed FE procedure an demonstrate the accuracy of the numerical models. Full scale model responses are also predicted using the reasonable method and parameters obtained in laboratory modeling.