• Proceedings of the KSME Conference
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• 2003.04a
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• pp.479-484
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• 2003

A non-contact 6D motion tracking system is proposed. The system consists of two color cameras, a color image grabber and a host computer, Motions of a floating vessel was measured by the constructed system. The instantaneous forces of the floating vessel are analyzed. The floating vessel was put on the water in a small water container in free conditions. The measured forces are reconstructed by the measurement results. The system can be used to non-contact measurements for 6D dynamic analysis of floating vessels.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.895-898
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• 2003

The higher precision is demanded in modem manufacturing and it requires the more accurate servo controller. Cross-coupling control (CCC) has been developed to improve contouring motion. In this paper we introduce a new nonlinear CCC that is based on contour-error-vector using a parametric curve interpolator. A vector from the actual tool position to the nearest point on the desire path is directly adopted. The contour-error-vector is determined by constructing a tangential vector of nearest point on desired curve and determining the vector perpendicular to this tangential vector from the actual tool position. Moreover, the vector CCC can apply directly and easily to free-form curves include convex and concave form. The experimental results on a three-axis CNC machine center show that the present approach significantly improves motion accuracy in multi-axis motion

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.164-168
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• 2004

The vibration analysis of an axially moving membrane are investigated when the membrane has the two sets of in-plane boundary conditions, which are free and fixed constraints in the lateral direction. Since the in-plane stiffness is much higher than the out-of-plane stiffness, it is assumed during deriving the equations of motion that the in-plane motion is in a steady state. Under this assumption. the equation of out-of\ulcornerplane motion is derived, which is a linear partial differential equation influenced by the in-plane stress distributions. After discretizing the equation by using the Galerkin method, the natural frequencies and mode shapes are computed. In particular, we put a focus on analyzing the effects of the in-plane boundary conditions on the natural frequencies and mode shapes of the moving membrane.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.718-723
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• 2000

Dynamic stability of an axially oscillating cantilever beam with a concentrated mass is investigated in this paper. The equations of motion are derived and the derived equations include harmonically oscillating parameters which originate from the motion-induced stiffness variation. Under certain conditions of the frequency and the amplitude of oscillating motion, parametric instabilities may occur. The multiple scale perturbation method is employed to obtain the stability analysis results. It is found that the system stability varies with the magnitude or the location of the concentrated mass. Instability increases as the concentrated mass approaches to the free-end or its magnitude increases.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.116-126
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• 2001

This paper suggests a numerical method to find optimal geometric path and minimum-time motion for a spatial 6-link manipulator arm (PUMA 560 type). To find a minimum-time motion, the optimal geometric paths minimizing 2 different dynamic performance indices are searched first, and the minimum-time motions are searched on these optimal paths. In the algorithm to find optimal geometric paths, the objective functions (performance indices) are selected to minimize joint velocities, actuator forces or the combinations of them as well as to avoid one static obstacle. In the minimum-time algorithm the traveling time is expressed by the power series including 21 terms. The coefficients of the series are obtained using nonlinear programming to minimize the total traveling time subject to the constraints of velocity-dependent actuator forces.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.211-214
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• 2011

비디오 압축 기법에서 움직임 추정 (Motion Estimation)은 매우 중요한 부분을 차지하는데, 그것은 움직임 추정이 화질과 인코딩 시간에 직접적으로 영향을 미치기 때문이다. 가장 기본적인 움직임 추정 기법은 전역 탐색 기법 (Full Search Algorithm, FSA)인데, 이는 가장 좋은 화질을 보여주긴 하지만 매우 많은 계산량을 필요로 한다는 단점이 있다. 따라서 좋은 화질을 유지하면서도 계산량을 낮추기 위한 많은 고속 탐색 알고리즘들이 제안되었다. 이 논문에서는 고속 탐색 알고리듬 중 하드웨어 구현 시 많은 이점을 가진 1비트 변환 알고리듬 (One-bit Transform-based Motion Estimation, 1BT)을 소개하고 1비트 변환 알고리듬의 방법에 있어서 기존의 1비트 변환 알고리듬의 PSNR을 유지하면서 좀 더 빠른 속도로 인코딩이 가능한 커널 및 알고리듬을 제시한다. 실험결과에 따르면 우리가 제안한 알고리듬은 기존의 1비트 변환 알고리듬과 비슷한 PSNR을 유지하면서 속도가 향상된 것을 볼 수 있었다.

• Macromolecular Research
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• v.15 no.2
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• pp.109-113
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• 2007

The surface molecular motion of monodisperse polystyrene (PS) films was examined using scanning vis-coelasticity microscopy (SVM) in conjunction with lateral force microscopy (LFM). The dynamic storage modulus, E', and loss tangent, $tan\delta$, at a PS film surface with number-average molecular weights, $M_n$, smaller than 30 k were found to be smaller and larger than those for the bulk sample, even at room temperature, meaning that the PS surface is in a glass-rubber transition or fully rubbery sate at this temperature when the $M_n$ is small. In order to quantitatively elucidate the dynamics of the molecular motion at the PS surface, SVM and LFM measurements were performed at various temperatures. The glass transition temperature, $T_g$, at the surface was found to be markedly lower than the bulk $T_g$, and this discrepancy between the surface and bulk became larger with decreasing $M_n$. Such an intensive activation of the thermal molecular motion at the PS surfaces can be explained in terms of an excess free volume in the vicinity of the film surface induced by the preferential segregation of the chain end groups.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.9 s.90
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• pp.910-918
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• 2004

The vibration analysis of an axially moving membrane are investigated when the membrane has the two sets of in-plane boundary conditions, which are free and fixed constraints in the lateral direction. Since the in-plane stiffness is much higher than the out-of-plane stiffness, it is assumed during deriving the equations of motion that the in-plane motion is in a steady state. Under this assumption, the equation of out-of-plane motion is derived, which is a linear partial differential equation influenced by the in-plane stress distributions. After discretizing the equation by using the Galerkin method, the natural frequencies and mode shapes are computed. In particular, we put a focus on analyzing the effects of the in-plane boundary conditions on the natural frequencies and mode shapes of the moving membrane.

• Structural Engineering and Mechanics
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• v.8 no.1
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• pp.53-72
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• 1999

The most important features of linear soil-foundation-structure interaction are reviewed, using stochastic modeling and considering kinematic interaction, inertial interaction, and structural distortion as three separate stages of the dynamic response to the free-field motion. The way in which each of the three dynamic stages modifies the spectral density of the motion is studied, with the emphasis being on interpretation of these results, rather than on the development of new analysis techniques. Structural distortion and inertial interaction analysis are shown to be precisely modeled as linear filtering operations. Kinematic interaction, though, is more complicated, even though it has a filter-like effect on the frequency content of the motion.

• Structural Engineering and Mechanics
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• v.54 no.3
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• pp.597-605
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• 2015

In this study, linear vibrations of an axially moving beam under non-ideal support conditions have been investigated. The main difference of this study from the other studies; the non-ideal clamped support allow minimal rotations and non-ideal simple support carry moment in minimal orders. Axially moving Euler-Bernoulli beam has simple and clamped support conditions that are discussed as combination of ideal and non-ideal boundary with weighting factor (k). Equations of the motion and boundary conditions have been obtained using Hamilton's Principle. Method of Multiple Scales, a perturbation technique, has been employed for solving the linear equations of motion. Linear equations of motion are solved and effects of different parameters on natural frequencies are investigated.