• The Journal of Advanced Prosthodontics
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• v.11 no.2
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• pp.88-94
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• 2019

PURPOSE. This study was conducted to investigate patterns of adjacent tooth displacement in the posterior implant with interproximal contact loss (ICL) by 3-D digital superimposition method. MATERIALS AND METHODS. Posterior partially edentulous patients, restored with implant fixed partial prostheses before 2011 and suffered from food impaction of ICL between 2009 and 2011, were included. Two dental casts, at the time of delivery and at the time of food impaction in a same patient, was converted into 3-D digital models through scanning and superimposition was performed to assess chronologic changes of the dentition. Directions of tooth displacement were evaluated and the amount of ICL was calculated. Correlations between the amount of ICL and elapsed time, or between the amount of ICL and age after function, were assessed at a significance level of P<.05. RESULTS. A total number of 13 patients (8 males, 5 females) with a mean age of $65.76{\pm}9.94years$ and 17 areas (4 maxillae, 13 mandibles) were included in this retrospective study. Teeth adjacent to the implant restoration showed complex displacements but characteristic tendency according to the location of the arch. The mean amount of ICL was $0.33{\pm}0.14mm$. Elapsed time from function to ICL was $61.47{\pm}31.27months$. There were no significant differences between the amount of ICL and elapsed time, or age (P>.05). CONCLUSION. Natural teeth showed various directional movements to result in occlusal change in the arch. The 3-D superimposition of chronologic digital models was a helpful method to analyze the changes of dentition and individual tooth displacement adjacent to implant restoration.

• Journal of the Korea Computer Industry Society
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• v.3 no.5
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• pp.569-574
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• 2002

We model the torsional oscillation of a suspension bridge, which is the forced sine-Cordon equation on a bounded domain. We use finite difference method to solve nonlinear partial differential equation numerically. The partial differential equation has multiple periodic solutions. Whether the span oscillates with small or large amplitude depends oかy on its initial displacement and velocity. Moreover, we observe that the qualitative properties are consistent with the behavior observed at the Tacoma Narrows Bridge on the day of its collapse.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.8
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• pp.763-770
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• 2012

The free vibration characteristics of fluid-filled cylindrical shells on partial elastic foundations are investigated by an analytical method. The cylindrical shell is fully or partially surrounded by the elastic foundations, these are represented by the Winkler or Pasternak model. The motion of shell is represented by the first order shear deformation theory to account for rotary inertia and transverse shear strains. The steady flow of fluid is described by the classical potential flow theory. The fluid-structure interaction is considered in the analysis. The effect of internal fluid can be considered by imposing a relation between the fluid pressure and the radial displacement of the structure at the interface. To validate the present method, the numerical example is presented and compared with the available existing results.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1002-1004
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• 1992

This paper presents a study of the partial circulating current type cycloconverter with a resonant circuit for induction heating. A method of input power factor improvement is proposed. Since the circulating currents flow through the circulating current reactors, the out-put currents are continuous and sinusoid. The proposed cycloconverter can keep the displacement factor at 1.0 by PWM control method regardless of load. The control functions are derived, the operational principles are described and the simulation and experimental results are presented.

• Structural Engineering and Mechanics
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• v.24 no.1
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• pp.51-62
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• 2006

Differential transform method (DTM) for free vibration analysis of both ends simply supported beam resting on elastic foundation is suggested. The fourth order partial differential equation for free vibration of the beam resting on elastic foundation subjected to bending moment, shear and axial compressive load is obtained by using Winkler hypothesis and small displacement theory. It is assumed that the material is linear-elastic, and that axial load and modulus of subgrade reaction to be constant. In the analysis, shear and axial load effects are considered. The frequency factors of the beam are calculated by using DTM due to the values of relative stiffness; the results are presented in graphs and tables.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.58-62
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• 2002

This paper proposes a new nonlinear controller to swing-up an inverted pendulum system mounted on a car. This controller considers not only the pendulum but also the displacement of the cart. A single-input multi-output system is considered to control the inverted pendulum by using partial feedback linearization and nonlinear additional input. The asymptotic stability of the system is shown by using Lyapunov function. The simulation results show effectiveness of the proposed controller.

• Proceeding of KASS Symposium
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• 2006.05a
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• pp.175-181
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• 2006

This paper presents an efficient reanalysis algorithm, named PRAS (Partial Reanalysis algorithm using Adaptable Substructuring), for the partially changed structures. The algorithm recalculates directly any displacement or member force under consideration in real time without a full reanalysis in spite of local changes in member stiffness or connectivity. The key procedures consists of 1) partitioning the whole structure into the changed part and the unchanged part, 2) condensing the internal degrees of freedom and forming the unchanged part substructure, 3) assembling and solving the new stiffness matrix from the unchanged part substructure and the changed members.

• Wind and Structures
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• v.28 no.6
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• pp.347-354
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• 2019

This study provides an approximate analytical solution to the fractional vibration problem of thin plate governing anomalous motion of plate subjected to in-plane loads. The method of variable separable is employed to transform the fractional partial differential equations under consideration into a fractional ordinary differential equation in temporal variable and a bi-harmonic plate equation in spatial variable. The technique of conformable fractional derivative is utilized to solve the resulting fractional differential equation and the approach of finite sine integral transform method is used to solve the accompanying bi-harmonic plate equation. The deflection field which measures the transverse displacement of the plate is expressed in terms of product of Bessel and trigonometric functions via the temporal and spatial variables respectively. The obtained solution reduces to the solution of the free vibration problem of thin plate in literature. This work shows that conformable fractional derivative is an efficient mathematical tool for tracking analytical solution of fractional partial differential equation governing anomalous vibration of thin plates.

• Structural Engineering and Mechanics
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• v.25 no.5
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• pp.501-518
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• 2007

In this work, a new approach is developed for dynamic analysis of a composite beam with an interply crack, based on finite element solution of partial differential equations with the use of the COMSOL Multiphysics package, allowing for fast and simple change of geometric characteristics of the delaminated area. The use of COMSOL Multiphysics package facilitates automatic mesh generation, which is needed if the problem has to be solved many times with different crack lengths. In the model, a physically impossible interpenetration of the crack faces is prevented by imposing a special constraint, leading to taking account of a force of contact interaction of the crack faces and to nonlinearity of the formulated boundary value problem. The model is based on the first order shear deformation theory, i.e., the longitudinal displacement is assumed to vary linearly through the beam's thickness. The shear deformation and rotary inertia terms are included into the formulation, to achieve better accuracy. Nonlinear partial differential equations of motion with boundary conditions are developed and written in the format acceptable by the COMSOL Multiphysics package. An example problem of a clamped-free beam with a piezoelectric actuator is considered, and its finite element solution is obtained. A noticeable difference of forced vibrations of the delaminated and undelaminated beams due to the contact interaction of the crack's faces is predicted by the developed model.

• Journal of Technologic Dentistry
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• v.35 no.1
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• pp.49-56
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• 2013

Purpose: The deformation characteristics induced by non-destructive stresses using piezoelectric transducer(PZT) were analyzed for 3-unit fixed partial dentures manufactured PFM, Everest(CAD/CAM) and Zirkonzahn(copy milling, MAD/MAM) by electron speckle pattern interferometery(ESPI). Methods: The ESPI analysis after loading the restoration with PZT by applying electric voltage of 900mV at the points of 10 mm above the base of the prostheses. Results: PFM and All-Ceramic Everest prostheses showed about 0.1 ${\mu}m$ while that of All- Ceramic Zirkonzahn prostheses showed 0.085 ${\mu}m$, demonstrating that Zirkonzahn displaced less. For PFM and All-Ceramic Zirkonzahn prostheses, the displacements were large at just below the loading point, while generalize displacement was shown over the loading point and weak connector areas for All-Ceramic Everest prostheses. Conclusion: We could find that the deformation characteristics induced by non-destructive stresses using PZT analyzed by ESPI were similar to the fracture strengths evaluated using universal testing machine.