• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.55-60
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• 1990

The objective of this study is to predict the nonlinear behavior of reinforced concrete shear walls, with the reinforcement uniformly distributed, under reversed cyclic loads. This study introduces joint Element Model which formulates the pulling out of rebars, slipping and intrusion of junction planes. The applicability of this study was experimental verfied by specimens SW1, SW2 and SW3 tested by authors, Wall1 by Paulay, SW16 and SW19 by Sheu. In almost specimen, the ratio of analytical to experimental maximum shear stress is within approximately 5%. In case of energy dissipation and maximum drift, the analytical results fully coincide with those of experiment.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2574-2581
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• 1993

A Shadow mask in C. R. T. (Cathod Ray Tube) undergoes a temperature increase due to impinging electron beams emitted from guns, and thermal deformation from such temperature rise may cause the electron beams to island on the panel, and thus give rise to depolarization. Hence the analysis of temperature distribution for a shadow mask is an important procedure for designing the shadow mask. In this paper, we are concerned with nonlinear finite element analysis of the temperature distribution on a shadow mask. First of all, we replace shadow mask, containing numerous apertures of a slit type, by an orthotropic shell without apertures, and calculate the apparent thermal conductivities. Because of thermal radiation, which is one of the major heat transfer mechanism for shadow masks, the resulting finite element equation is nonlinear and solved by the Newton method. Finally numerical examples are illustrated for a 21" FST(Full Square Tube) shadow mask, and followed by discussion.sion.

• Structural Engineering and Mechanics
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• v.29 no.2
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• pp.117-134
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• 2008

A new adaptive dual reciprocity boundary element method for dynamic analysis of 3-D structures is presented in this paper. It is based on finding the best approximation function of a radial basis function (RBF) group $f=r^n+c$ which minimize the error of displacement field expansion. Also, the effects of some parameters such as the existence of internal points, number of RBF functions and position of collocation nodes in discontinuous elements are investigated in this adaptive procedure. Three numerical examples show improvement in dynamic response of structures with adaptive RBF in dual reciprocity with respect to ordinary BEM.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.108-113
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• 2004

According to our fatigue tests carried out at 20 Hz, R=0.1 on transversely butt~welded joints, fatigue strengths of as-welded specimens, that is, specimens having residual stress are higher than those of annealed specimens in short life range, but vice verse in long life range. This behavior seems to be concerned mainly with residual stress relaxation by applied loading. After analyzing the welding process, we conducted finite element analysis to quantify the degree of residual stress relaxation. By taking into account residual stress relaxation, modified Goodman diagram, and nominal stress, we evaluated the fatigue life of the welded joint from the S-N curve for the parent material. The estimated results are in a good agreement with the experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.429-432
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• 2004

This paper discussed finite element method(FEM) models of the reinforced concrete rectangular shear walls with opening configuration and analysed under constant axial and monotonic lateral load using ABAQUS. The research comprises constitutive models to represent behavior of the materials that compose a wall on the basis of experimental data, development of techniques that are appropriate for analysis of reinforced concrete structures, verification, and calibration of the global model for reinforced concrete shear walls of increasing complexity. Results from the analyses of these FEM models offers significant insight into the flexural behavior of benchmark data.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.56-58
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• 1995

Dynamic characteristics of the vector controlled induction motor has been analysed using d-q equivalent circuit. However, for the design of the induction motor, the analysis of an accurate response characteristic are needed. In this paper, dynamic characteristic analysis method using 2-D Finite Element Method (FEM), which takes the motion equation of the rotor into account and considers the physical motion of the rotor by an automatic subdivision of mesh, are explained.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.685-689
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• 2001

We carried out these experiments to examine the effects of element substitution of Co and La-Co for Sr-ferrite. The calcined properties of Co and La-Co element substitution were examined, and also the sintered magnetic properties were measured with the stoichiometric condition. The magnetic properties of $(La-Co)_{0.3}-SrM$ composition are as follows; $(M_s)$: 71.08 emu/g, $iH_c$: 4.38 kOe and $B_r$ : 4.18 kG, $iH_ c$ :4.35 kOe, $BH_{max}$: 4.3 MGOe. The $BH_{max}$ value was increased up to 10 % compared with conventional values. Our results imply that the magnetic properties of Sr-ferrite can be improved by the substitution of those elements.

• Korean Journal of Metals and Materials
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• v.48 no.11
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• pp.974-980
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• 2010

Various types of steel, namely, 0.35C, 0.2C-Cr, and 0.2C-Cr-Mo steels, were quenched and tempered by high-frequency induction heat treatment. The type, size, and spheroidization of the carbides varied depending on the tempering temperatures ($450{\sim}720^{\circ}C$). During the tempering process, the carbide was precipitated in the martensite matrix. The 0.35C, 0.2C-Cr, and 0.2C-Cr-Mo steels contained carbides that were smaller than 120 nm. The carbide was spheroidized as the tempering temperature increased. Owing to the fine microstructure and spheroidization of the carbides, all three steels had a high tensile strength as well as yield ratio and reduction of area. In the case of the 0.2C-Cr steel, the use of Cr as an alloying element facilitated the precipitation of alloyed carbides with an extremely small particle and resulted in an increase in the spheroidization rate of the carbides. As a result, a large reduction of area was achieved (>70%). The 0.2C-Cr-Mo steel had the highest tensile strength because of the high hardenability that can be attributed to the presence of alloying elements (Cr and Mo). Quenching and tempering steels by induction heat treatment resulted in a high strength of over 1 GPa and a large reduction of area (>70%) because of the rapid heating and cooling rates.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.251-258
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• 2018

This work illustrates the progress of a TAS activity at exploring the challenges and the benefits of the Virtual Shaker Testing (VST) approach. The definition and the validation of new computational methodologies with respect to the state of the art were encouraged throughout this activity. The shaker Finite Element (FE) model in lateral configuration was built for the purpose and it was merged with the SpaceCraft (S/C) FE model, together with the S/C-Shaker adapter. FE matrices were reduced through the Craig-Bampton method. The VST transient analysis was performed in MATLAB(R) numerical computing environment. The closed-loop vibration control is accounted for and the solution is obtained through the fourth-order Runge Kutta method. The use of pre-existing built-in functions was limited by authors with the aim of tracing the impact of all the problems' parameters in the solution. Assumptions and limitations of the proposed methodology are detailed throughout this paper. Some preliminary results pertaining to the current progress of the activity are thus illustrated before the conclusions.

• Journal of the Korean Mathematical Society
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• v.40 no.2
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• pp.241-250
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• 2003

Let (B, m$_{B}$, k) be a maximal commutative $textsc{k}$-subalgebra of M$_{m}$(k). Then, for some element z $\in$ Soc(B), a k-algebra R = B［X,Y］/I, where I ＝ (m$_{B}$X, m$_{B}$Y, X$^2$- z,Y$^2$- z, XY) will create an interesting maximal commutative $textsc{k}$-subalgebra of a matrix algebra which is neither a $C_1$-construction nor a $C_2$-construction. This construction will also be useful to embed a maximal commutative $textsc{k}$-subalgebra of matrix algebra to a maximal commutative $textsc{k}$-subalgebra of a larger size matrix algebra.gebra.a.