• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권2호
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• pp.151-156
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• 2008

Different kinds of forces can be applied to the biological tissue. The analysis of the applied force is highly important to explain the mechanism of cellular response. In this study, the applied force to the collagen gel was analyzed by the finite elements analysis. The model received two different kinds of static force (compression and tension). The force range was 50g to 400g. In results, von Mises stress was concentrated in the peripheral region in the compression model. It was concentrated in the central area in the tension model. However, the compressive force was high in the peripheral area of the compression model and the tensional force was also high in the same area of the tension model. In conclusion, the applied force could be different to the region and it should be considered in the experiment to analyze the effects of the mechanical force on the cells.

• 한국전자통신학회논문지
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• 제7권5호
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• pp.1067-1072
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• 2012

현재 선형 전동기는 많은 연구가 진행되어 그 응용분야가 산업전반에 확대되고 있다. 이중 반송장치 분야에서 영구자석 선형 동기 전동기(Permanent Magnet Linear Synchronous Motor:이하 PMLSM)가 각광을 받고 있다. 영구자석 선형 동기 전동기는 구조적으로 간단하며 고속화 고추력화 등의 장점을 가지고 있지만 전기자를 반송경로 전장에 배치하는 지상 1차측 시스템을 장거리 반송장치에 적용하면 재료비용의 증가 및 제작시간 증가 등의 문제점이 발생한다. 따라서 전기자를 분산(불연속) 배치하는 방식이 제안되고 있다. 하지만 이러한 전기자 분산배치 방식은 구조적으로 단부가 존재하고 이러한 단부에 의해 코깅력이 발생한다. 이는 추력 맥동의 원인이 되며, 소음과 진동을 발생시킨다. 따라서, 본 연구에서는 전기자를 분산배치 할 경우 필연적으로 생기는 단부에 의한 코깅력을 저감하기 위해 Bifurcating을 적용한 집중권 PMLSM에 보조극 설치법을 제안한다. 또한 그에 따른 단부 코깅력 특성을 2차원 유한요소법(FEA)을 이용하여 분석하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.911-916
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• 2004

The paper deals with the dynamic stability of a cantilevered Timoshenko beam on partial elastic foundations subjected to a follower force. The beam is assumed to be a Timoshenko beam with a concentrated mass taking into account its rotary inertia and shear deformation. Governing equations are derived by extended Hamilton's principle, and FEM is applied to solve the discretized equation. Critical follower force depending on the attachment ratios of partial elastic foundations, concentrated mass and rotary inertia of the beam is fully investigated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1311-1320
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• 2000

In this study, shape memory alloy(SMA) wires and piezoceramic actuators(PZT's) are employed in order to generate higher modes on the beam deformations. Compressive force is generated and applied to the beam by the pre-strained SMA wires attached at both ends of the beam. PZT's apply concentrated moments to several locations on the beam. Combinations of the compressive force and concentrated moments are investigated in order to understand the higher-mode deformation of beams. The first desired mode shape is obtained by controlling the temperature of the SMA wires. The first and third mode shapes are performed experimentally by heating SMA wires up to phase transformation temperature. The adaptive wing is defined as a wing whose shape parameters such as the camber, wing twist and thickness can be varied in order to change the wing shape for various flight conditions. In this research, control of the camber has been studied. The wing model consists of three plates and many ribs. Two of the plates are placed parallel to each other and they are clamped at one edge. Third plate connects the other edges of the parallel plates together. Each rib is made of SMA wire and connected to the parallel plates. It generates concentrated force and applies to the plates in oblique directions. The PZT's are bonded onto the plates and exert concentrated moments upon the plate at several locations. The object of this research is to generate various shape of wing by combining the concentrated forces and moments.

• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1693-1699
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• 2016

The oscillation character of permanent magnetic motor is highly related to its slot-pole match. By calculating air-gap magnet field and radial electromagnetic force of 6-phase fractional-slot concentrated-winding permanent magnetic motor with slot-pole match of 48/44, 48/46, 48/50 and 48/52 under no load and load status, oscillation character of permanent magnetic motor is analyzed. A 20kW prototype with 48 slots and 44 poles is designed. With many sensors attaching to the corresponding parts, oscillatory acceleration is measured, and spectrum of oscillation frequency is recorded as well. The experiment results give proof to the analysis method for permanent magnetic motor oscillation in this paper.

• Tribology and Lubricants
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• 제14권1호
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• pp.54-63
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• 1998

In many practical lubricated contacts such as a rough concentrated contact on the sliding of nominally flat surfaces, the fluid may be of molecular (nanometer) scale owing to the asperity interactions on the surfaces. Under this condition, there is insufficient lubricant on the concentrated contact spot to maintain a realistic continuum. Rheological behavior for this kind of concentrated contact has been studied extensively to know whether the application of viscous fluid model is appropriate. The interaction of two rough surfaces is simplified as perfectly flat-rough surfaces contact under certain conditions by "composite topography" and for a nanometer scale fluid film, three kinds of rheological fluid behavior are analyzed in elastohydrodynamic asperity point contact.t contact.

• Coupled systems mechanics
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• 제8권6호
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• pp.501-522
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• 2019

The present study is concerned with the thermoelastic interactions in a two dimensional axisymmetric problem in transversely isotropic thermoelastic solid using new modified couple stress theory without energy dissipation and with two temperatures. The Laplace and Hankel transforms have been employed to find the general solution to the field equations. Concentrated normal force, normal force over the circular region, concentrated thermal source and thermal source over the circular region have been taken to illustrate the application of the approach. The components of displacements, stress, couple stress and conductive temperature distribution are obtained in the transformed domain. The resulting quantities are obtained in the physical domain by using numerical inversion technique. The effect of two temperature varying by taking different values for the two temperature on the components of normal stress, tangential stress, conductive temperature and couple stress are depicted graphically.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.695-700
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• 2000

The dynamic stability of spinning beam with free boundary conditions for both edges subjected to a tip follower force $P_0+P_1cos{\Omega}t$ is analyzed. It is studied that the beam has a concentrated mass. and then the effects of the axial locations of the mass are studied. The beam is modelled with the Timoshenko type shear deformations. The Hamilton's principle is used to derive the equations of motion, and the critical spinning speed of a beam subjected to a follower force with various non-dimensional parameters is investigated. The finite elements are used with $C^0$ continuity to analyze the spinning beam model, and the method of multiple scales is tried to investigate the dynamic instability regions. The governing equations of motion involve periodic coefficients, which are not in the form of standard Mathieu-Hill equations. The result shows that the concentrated mass increases the dynamic stability of the spinning free-free beam subjected to a thrust.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제26회 추계학술대회
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• pp.173-182
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• 1997

In many practical lubricated contacts such as a rough concentrated contact on the sliding of nominally flat surfaces, the fluid may be of molecular (nanometer) scale owing to the asperity interactions on the surfaces. Under this condition, there is insufficient lubricant on the concentrated contact spot to maintain a realistic continuum. Rheological behavior for this kind of concentrated contact was studied to know whether the application of viscous fluid model is appropriate. The interaction of two rough surfaces is simplified as perfectly flat-rough surfaces contact under certain conditions by "composite topography" and for a nanometer scale fluid film, three kinds of rheological fluid behavior are analyzed in elastohydrodynamic asperity point contact.t contact.

• Structural Engineering and Mechanics
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• 제47권2호
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• pp.149-166
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• 2013

Flexible behaviors in new aerospace structures can lead to a degradation of their control and guidance system and undesired performance. The objectives of the current work are to analyze the vibration resulting from the propulsion force on a Single Stage to Orbit (SSTO) launch vehicle (LV). This is modeled as a follower force on a free-free Euler-Bernoulli beam consisting of two concentrated masses at the two free ends. Once the effects on the oscillation of the actuators are studied, a solution to reduce these oscillations will also be developed. To pursue this goal, the stability of the beam model is studied using Ritz method. It is determined that the transverse and rotary inertia of the concentrated masses cause a change in the critical follower force. A new dynamic model and an adaptive control system for an SSTO LV have been developed that allow the aerospace structure to run on its maximum bearable propulsion force with the optimum effects on the oscillation of its actuators. Simulation results show that such a control model provides an effective way to reduce the undesirable oscillations of the actuators.