• Structural Engineering and Mechanics
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• v.4 no.4
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• pp.415-424
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• 1996

This paper presents a newly suggested calculation method in which an arbitrary quadrilateral element with curved sides is transformed to a normal rectangular one by mapping of coordinates, then the two-dimensional spline is adopted to approach the displacement function of this element. Finally the solution can be obtained by the least-energy principle. Thereby, the application field of Spline Finite Element Method will be extended.

• Computers and Concrete
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• v.4 no.1
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• pp.49-66
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• 2007

The objective of this paper is to provide experimental data on the propagation of curved crack-surfaces and the respective load-displacement diagrams for the validation of numerical models for cracking of concrete, subjected to three-dimensional stress states. To this end beam-shaped specimens are subjected to combined bending and torsional loading, leading to the formation of a spatially curved crack-surface. The experimental data contain the evolution of the load and of the strains at selected points in terms of the crack mouth opening displacement and the propagation of the crack surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.300-302
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• 1999

The standing waves of the fourth bending mode of vibration and first longitudinal mode of vibrator were utilized to construct a ultrasonic linear motor. The geometrical dimensions of the vibrator were determined by Euler-Bernoulli theoty. FEM(finite element method) employed to calculate the vibration mode of the metal-piezoceramic composite thin plate vibrator. ANSYS was used to design positions of the projections and calculate displacement of vibrator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.49-52
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• 2008

In this study, multilayer structured ultrasonic linear motor was simulated using Atila for investigating its optimum driving conditions. The ultrasonic linear motors mainly consist of an ultrasonic vibrator to generate elliptical displacement. The ultrasonic linear motor simulated in this paper was the use of the 1st longitudinal(Ll) and 4th bending vibrations (B4). Whit the increase of the number of piezoelectric actuator layers, displacement of node was increased. Maximum total displacement of node was about $3,91{\mu}m$ at the 13 layered ultrasonic motor under 5 V.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.385-389
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• 2003

To make high speed spindle system work properly, sensors with outstanding resolution and dynamic characteristics are essential. An optical fiber displacement sensor is based on simple principles. Electrical signal responds to the optical flux change due to the displacement change between a target and a sensor probe. In this paper, the performance of optical fiber displacement sensor has been investigated according to properties of optical fiber Firstly, optical loss has been measured before and after polishing optical fiber endface. Secondly, allowance of optical fiber bending has been tested. thirdly sensitivity and linear range of the sensor has been found out according to the shape of cross section of optical fiber.

• Steel and Composite Structures
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• v.43 no.1
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• pp.129-137
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• 2022

Dynamic response of a laminated porous concrete beam reinforced by nanoparticles subjected to harmonic transverse dynamic load is investigated considering structural damping. The effective nanocomposite properties are evaluated on the basis of Mori-Tanaka model. The concrete beam is modeled by the sinusoidal shear deformation theory (SSDT). Utilizing nonlinear strains-deflection, energy relations and Hamilton's principal, the governing final equations of the concrete laminated beam are calculated. Utilizing differential quadrature method (DQM) as well as Newmark method, the dynamic displacement of the concrete laminated beam is discussed. The influences of porosity parameter, nanoparticles volume percent, agglomeration of nanoparticles, boundary condition, geometrical parameters of the concrete beam and harmonic transverse dynamic load are studied on the dynamic displacement of the laminated structure. Results indicated that enhancing the nanoparticles volume percent leads to decrease in the dynamic displacement about 63%. In addition, with considering porosity of the concrete, the dynamic displacement enhances about 2.8 time.

• Geomechanics and Engineering
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• v.36 no.4
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• pp.407-416
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• 2024

Dynamic response of a rock tunnels by laminated porous concrete beam reinforced by nanoparticles subjected to harmonic transverse dynamic load is investigated considering structural damping. The effective nanocomposite properties are evaluated on the basis of Mori-Tanaka model. The concrete beam is modeled by the exponential shear deformation theory (ESDT). Utilizing nonlinear strains-deflection, energy relations and Hamilton's principal, the governing final equations of the concrete laminated beam are calculated. Utilizing differential quadrature method (DQM) as well as Newmark method, the dynamic displacement of the concrete laminated beam is discussed. The influences of porosity parameter, nanoparticles volume percent, agglomeration of nanoparticles, boundary condition, geometrical parameters of the concrete beam and harmonic transverse dynamic load are studied on the dynamic displacement of the laminated structure. Results indicated that enhancing the nanoparticles volume percent leads to decrease in the dynamic displacement about 63%. In addition, with considering porosity of the concrete, the dynamic displacement enhances about 2.8 time.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.12-18
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• 2021

The purpose of this study is to effectively mitigate the bending displacement that occurs in the bridge due to forced vibration. We developed CTMD (Combine Tuned Mass Damper) that combines the relationship between spring and mass to control the bending behavior of simple beams. The experiment was conducted to confirm the control effect according to the change in the mass ratio of the developed CTMD. The developed CTMD is designed and manufactured so that the mass ratio can be adjusted according to the characteristics of the bridge. The maximum load of the spring applied to CTMD was fixed at 33.15 N. In order to evaluate the performance of the developed CTMD, a simple beam composed of hinges and rollers as boundary conditions was fabricated. In the experimental method, a CTMD was installed in the center of a simple beam and the deflection displacement according to the mass ratio was measured. The shaking condition was shaken at 3 Hz to induce the maximum bending behavior of the simple beam. As a result of the experiment, it was confirmed that when the optimal mass ratio was 2.1, the damping rate of the bending behavior displacement was about 71.2 %, indicating the best control effect.

• The korean journal of orthodontics
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• v.14 no.1
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• pp.75-92
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• 1984

This study attempted to analyze the distribution of stress, to examine the bending effect in the mandible according to the pulling directions and determine on which pulling directions are adequate when an orthopedic force was applied to the mandible. An orthopedic force, 500gm, was applied to the gnathion, one point of the chin area, in three directions. The three directions were ; high puli' from gnathion to the center of condyle head, and vertical pull, from gnathion to a parallel line with the posterior border of the ramus, and medium pull, from the gnathion to a parallel line with the lower border of mandible. The distribution of principal stress, bending moment and amount of displacement within the mandible was analyzed by a 3-dimensional finite element method and that of the various portions of mandible were computed and compared according to the pulling directions. The results were as follows : 1. The bending moment of each part of a mandible has been found to be markedly larger in case of vertical pull than in case of either high pull or medium pull. In vertical pull the bending moment turned out to largest at the condyle head and neck portion, the gonial angle portion, the coronoid portion and the ascending ramus portion, respectively, while comparatively large at the cuspid and bicuspid portion and the first molar portion. In case of high pull it was largest at the gonial angle portion and becoming smaller at the coronoid portion, the ascending ramus portion, the condyle head and neck portion, and the cuspid and bicuspid portion, in that order. In case of medium pull, however, the bending moment was largest at the condyle head and neck portion, becoming smaller at the first molar portion, the ascending ramus portion, the coronoid portion, the cuspid and bicuspid portion, and gonial angle portion, in that order. 2. As for the bending effect it was calculated to be mostly oriented downward at the mandibular body and backward at the mandibular ramus in both high pull and vertical pull. In case of medium pull it was oriented upward at the mandibular body and forward at the mandibular ramus. 3. The bending effect also turned out to be mostly oriented outward in case of high pull and medium pull, and inward in vertical pull. 4. At the mandibular body and ramus, the bending effect in the upward-downward direction and that in the forward-backward direction were found to be larger than in the inward-outward direction. 5. If and when we expect any correcting effect on the mandibular protrusion by means of the chin cup appliance, we can say sure as conclusion that high pull and vertical pull are more effective than medium pull.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.423-428
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• 2012

As the speed of high speed train increases, the prediction of ride comfort becomes important. The exciting frequencies due to rail irregularity in high-speed train closes to the second and third natural frequencies of the carbody. The dynamic characteristics of railway vehicles should be checked by modal analysis numerically and experimentally. In this study the bending test for railway vehicle is reviewed and the impact test is suggested to find the natural frequencies and the mode shapes of the carbody. The validity of the impact test is checked with the test for a sample plate which reflects the aspect ratio of the original carbody. The bending test by the impact and the displacement methods of JIS E7105 for a prototype carbody were done in the field and compared. The results show that the impact test can find more accurate natural frequencies and the mode shapes of the carbody than those of the displacement method.