• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.80-81
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• 2002

MR(magnetoresistance)은 물질의 저항이 자기장에 의해 변하는 물리적인 변화(physical MR)와 기하학적인 요소, 즉 sample의 모양과 contact의 크기 등에 의한 변화(geometric MR)의 합으로 나타낸다.[1] Physical MR은 자기장에 따른 비저항 또는 이동도(mobility)의 변화로 나타낼 수 있고, geometric MR은 로렌츠 힘에 의해 전류의 흐르는 방향이 변하면서 일어난다. 본 연구에서는 physical MR이 거의 없는 반도체(InAs)와 비교적 큰 physical MR을 가지는 반도체(HgCdTe)의 geometric factor를 고려한 MR의 향상에 대하여 연구하였다. (중략)

• Proceedings of the KSR Conference
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• 2006.05b
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• pp.446-446
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.139-140
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• 2011

• Journal of Industrial Technology
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• v.28 no.A
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• pp.81-88
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• 2008

Generally, Hertz theory is used to analyze the contact problem of two bodies. It is simple derivation of solution in the contact part. And calculation time is short Moreover, it can mean well that many wear occurs relatively. However, material property becomes plastic deformation when large perpendicular pressure acts on a small contact surface product. In this case, Hertz theory is inapplicable. Therefore this thesis carried the finite element analysis in consideration of material elasticitystrain and the shape of the geometric from contact point. And it compared with Hertz theory that change of the contact surface and contact pressure.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.177-181
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• 2005

Although there are many ways to measure the diameter of a cylindrical object, in this study, the diameter of a cylindrical objects were measured by the geometric optical method and interference-diffraction method which are two kinds of tipical non-contact methods. In geometric optical method, the curved laser beam is formed on the cylindrical surface by spreading the inclined laser beam using the cylindrical lens. The curve is captured by CCD camera and the diameter is calculated by geometry. And the interference and diffraction patterns of investigated cylindrical objects are analyzed in interference-diffraction method. In this study, the cylindrical objects, whose diameters are $0.05\;mm\;\~\;100.50\;mm$ were measured by the geometric optical method and interference-diffraction method. The results show that in each method, the relative errors of the measurement are within $2\%$ and $1\%$, respectively and these non-contact methods can be applied in the quick measurement of many objects.

• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.411-421
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• 2005

The development and implementation of an appropriate methodology for the accurate geometric description of track models is proposed in the framework of multibody dynamics and it includes the representation of the track spatial geometry and its irregularities. The wheel and rail surfaces are parameterized to represent any wheel and rail profiles obtained from direct measurements or design requirements. A fully generic methodology to determine, online during the dynamic simulation, the coordinates of the contact points, even when the most general three dimensional motion of the wheelset with respect to the rails is proposed. This methodology is applied to study specific issues in railway dynamics such as the flange contact problem and lead and lag contact configurations. A formulation for the description of the normal contact forces, which result from the wheel-rail interaction, is also presented. The tangential creep forces and moments that develop in the wheel-rail contact area are evaluated using : Kalker linear theory ; Heuristic force method ; Polach formulation. The methodology is implemented in a general multibody code. The discussion is supported through the application of the methodology to the railway vehicle ML95, used by the Lisbon metro company.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.409-414
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• 2005

It is difficult to apply the Hertz theory to the wheel-rail contact problem which has the complicated geometric form and plastic deformation. Therefore, we perform the elastic-plastic FE analysis and compare the results with those of Hertz theory. Kalker's simplified theory of rolling contact is used to discretize the contact patches and calculate local traction and slip. The wear volumes are calculated using Archard wear equation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.219-224
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• 2002

This paper aims to derive a mathematical model of the dynamics of handling tasks in robot finger which stable grasping and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraint of tight area-contacts is formulated by Lagrange's equation. Secondly, problems of controlling both the internal force and the rotation angle of the grasped object under the constraints of area-contacts of tight area-contacts are discussed. The effect of geometric constraints of area-contacts on motion of the overall system is analyzed and a method of computer simulation for overall system of differential-algebraic equations is presented. Thirdly, simulation results are shown and the effects of geometric constraints of area-contact is discussed. Finally, it is shown that even in the simplest case of dual single D.O.F manipulators there exists a sensory feedback from sensing data of the rotational angle of the object to command inputs to joint actuators and this feedback connection from sensing to action eventually realizes secure grasping of the object, provided that the object is of rectangular shape and motion is confined to a horizontal plane.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.114-117
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• 2004

The purpose of this study is to investigate geometric effect on the contact stress at a lip seal. The geometries of interest were angle, thickness of lip seal and width of contact surface. The contact stress was calculated by using a coupled thermo-mechanical analysis method. The friction thermal load between lip seal and sleeve was adopted to design load. Based on the FEA results, design variables for controlling the maximum contact stress at the lip seal were identified.

• Structural Engineering and Mechanics
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• v.12 no.1
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• pp.35-50
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• 2001

A numerical methodology is presented in this paper for the geometrically non-linear analysis of slender uni-dimensional structural elements under unilateral contact constraints. The finite element method together with an updated Lagrangian formulation is used to study the structural system. The unilateral constraints are imposed by tensionless supports or foundations. At each load step, in order to obtain the contact regions, the equilibrium equations are linearized and the contact problem is treated directly as a minimisation problem with inequality constraints, resulting in a linear complementarity problem (LCP). After the resulting LCP is solved by Lemke's pivoting algorithm, the contact regions are identified and the Newton-Raphson method is used together with path following methods to obtain the new contact forces and equilibrium configurations. The proposed methodology is illustrated by two examples and the results are compared with numerical and experimental results found in literature.