• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.247-250
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• 1995

The development and empirical validation of a mathematical model for predicting the depth of deformed layer in a machined surface are presented. The main assumption for develioping this model is that there is a linear relationship between plastic strain and the depth to which it extends. The model relates the work required to shear the workpice material to the work needed to compress the workpiece material ahead of the cutting tool. The results show that the percent difference between the calculated and the measured depth of deformed layer ranges form 4 percent to 19 percent. An improvement of the model is suggested through application of actual distribution data of plastic strain.

• Earthquakes and Structures
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• v.8 no.5
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• pp.1113-1126
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• 2015

A damage localization algorithm based on Operational Deformed Shapes and known as Interpolation Damage Detection Method, is herein applied to the finite element model of a cable stayed bridge for detecting and localizing damages in the stays and the supporting steel beams under the bridge deck. Frequency Response Functions have been calculated basing on the responses of the bridge model to low intensity seismic excitations and used to recover the Operational Deformed Shapes both in the transversal and in the vertical direction. The analyses have been carried in the undamaged configuration and repeated in several different damaged configurations. Results show that the method is able to detect the damage and its correct location, provided an accurate estimation of the Operational Deformed Shapes is available. Furthermore, the damage detection algorithm results effective also when damages coexist at the same time at several location of the cable-stayed bridge members.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.228-230
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• 2004

Samples of the aluminum alloy 3103 sheets were repeatedly deformed by ECAR up to twelve passes. Shear textures developed after the first passage of ECAR. However, the intensity of shear texture components decreased with increasing number of ECAR passages. Observations by TEM and EBSD revealed that the degree of misorientations within the deformed grains increased with increasing number of ECAR passes. Changes in textures and microstructures were hardly observed during recrystallization anneal. Upon subsequent annealing, the samples deformed by a large number of ECAR passes displayed a continuous grain growth. A higher deformation by ECAR resulted in a slower softening, which reflects the stability of ultra-fine grains against the grain growth.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.141-147
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• 1998

A plastically deformed layer in the precision machined surface affects in various forms the physical properties of machined components such as the fatigue strength, the dimensional instability, microcracks and the stress corrosion cracking. These physical properties, so called surface integrity, are very important for designing highly stressed and critically loaded components. Typical plastic strains in the precision machined surface are very difficult to measure, since they are located within a very short distance from the surface and they change very rapidly. A new way is suggested to determine the residual strain in plastically deformed materials by analyzing the plastically deformed layer after a subsequent recrystallization process. This investigation is to explore a new technique for measuring plastic strain in machining applications, and in particular, to and the effect of cutting parameters(rake angle, depth of cut, specific cutting energy), on the plastic strains and strain energy.

• Journal of Korean Academy of Nursing
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• v.34 no.5
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• pp.685-692
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• 2004

Purpose: This study was to examine the effects of Taping therapy on the deformed angle of the foot and pain in hallux valgus patients. Method: The subjects were 24 feet from 15 patients who were diagnosed withhallus valgus at the orthopedic department of K University Hospital in Seoul. Taping therapy was conducted 15 times overall during a four-week period. Data was analyzed using descriptive statistics and t-test. Result: The deformed angle of the foot of the hallus valgus patients significantly improved from 21.95(4.38) to 18.75(4.80) after Taping therapy. Pain significantly decreased from 4.73(1.56) to 3.45(2.21) after Taping therapy. Conclusion: The result shows that Taping therapy is effective in improving the deformed angle of the foot and in decreasing pain in the hallux valgus patients.

• Transactions of Materials Processing
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• v.13 no.8
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• pp.704-709
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• 2004

The effect of annealing temperature on microstructures and mechanical properties of the 5052 Al sheets rolled 88% reduction at cryogenic temperature was investigated for the annealing temperature of 150 ~ $300^{\circ}C$, in comparison with those rolled at room temperature. The presence of equiaxed grains, whose size is about 200nm in a diameter, was observed in the alloy deformed 88% and annealed $200^{\circ}C$ for an hour. When compared with the deformation at room temperature, the deformation at cryogenic temperature showed the higher strengths and equivalent elongation after annealing at the annealing temperature below $200^{\circ}C$. However, for annealing above $250^{\circ}C$ materials deformed at cryogenic temperature showed the lower strength than those deformed at room temperature. This behavior might be attributed to the higher rate of recrystallization and growth in materials deformed at cryogenic temperature during annealing, due to the lager density of dislocations accumulated during the deformation.

• Structural Engineering and Mechanics
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• v.6 no.2
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• pp.173-183
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• 1998

In the shape design of flexible structures, it is useful to predict the initial shape from the desirable large deformed shapes under some loading conditions. In this paper, we present a numerical procedure of an initial shape determination problem for hyperelastic materials which enables us to calculate an initial shape corresponding to the prescribed deformed shape and boundary condition. The present procedure is based on an Arbitrary Lagrangian-Eulerian (ALE) finite element method for hyperelasticity, in which arbitrary change of shapes in both the initial and deformed states can be treated by considering the variation of geometric mappings in the equilibrium equation. Then the determination problem of the initial shape can be formulated as a nonlinear problem to solve the unknown initial shape for the specified deformed shape that satisfies the equilibrium equation. The present approach can be implemented easily to the finite element method by employing the isoparametric hypothesis. Some basic numerical results are also given to characterize the present procedure.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.1
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• pp.111-116
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• 2001

A practical scheme to reduce failure of the PCB(Printed Circuit Board) of a monitor is introduced using deformed mode shape under mechanical shock. When the monitor is given critical shock loads, cracks are commonly initiated at the tip of a hole on the PCB. Accordingly, a deformed mode shape of the PCB is obtained using a FEM code to define a weak point on the PCB under mechanical shock, and then the position and direction of the hole is determined to prevent the failure at the critical mode shape. Also, the stress intensity factor around the weak point on the PCB is calculated to check the possibility of fracture by normal tensile stress. In conclusion, present research is useful to assist the practical design of components-layout on the PCB.

• Transactions of Materials Processing
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• v.28 no.4
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• pp.175-182
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• 2019

In this study, compression process is performed on the seamless E235 pipe using the newly developed compression technology for seamless pipe. Experimental analysis on the heterogeneity of microstructures and mechanical properties of the deformed seamless pipe is conducted. As a result, the correlation between microstructures and mechanical properties are determined. The spatial distribution of effective stress and effective strain developed in the seamless pipe deformed through compression is analyzed using the finite element method (FEM) based on different inner pressure conditions. From the results of the FEM, the impact of the inner pressure on effective stress and effective strain of the seamless pipe deformed through compression can be understood theoretically.

• Communications of the Korean Mathematical Society
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• v.34 no.4
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• pp.1175-1199
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• 2019

We construct a general bi-basic inverse series relation which provides extension to several q-polynomials including the Askey-Wilson polynomials and the q-Racah polynomials. We introduce a general class of polynomials suggested by this general inverse pair which would unify certain polynomials such as the q-extended Jacobi polynomials and q-Konhauser polynomials. We then emphasize on applications of the general inverse pair and obtain the generating function relations, summation formulas involving the associated polynomials and derive the p-deformation of some of the q-analogues of Riordan's classes of inverse series relations. We also illustrate the companion matrix corresponding to the general class of polynomials; this is followed by a chart showing the reducibility of the extended p-deformed Askey-Wilson polynomials as well as the extended p-deformed q-Racah polynomials.