• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.4
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• pp.301-314
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• 1990

This paper is an attempt to use vision-pattern recognition technique to analyzation on a hidden rigid body motion. Specially shaped rod, rigidly connected to the hidden body is extended to the ouside of hiding object so that a camera may catch the motion data. Every motion can be described with translatio and rotation. But translation can be explanied with ratation with a infinitly far centroid. Motion analysis is to find the instantaneous centroid and ratation angle. With this theory jaw motion is analyzed in this paper.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.528-531
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• 2009

본 연구에서는 두 스프링으로 지지된 강체가 회전하는 Timoshenko 축을 따라 이동할 때, 그 계의 동적응답 특성을 해석하였다. 운동방정식은 Hamilton의 원리에 따라 유도되었다. 유도된 운동방정식을 이용하여 주요 설계 파라미터 변화에 따른 응답특성을 해석하였다. 해석시 설계파라미터를 무차원 변수화 하여 속도비, 질량비, 회전수비 등 그 변화에 따른 응답특성을 비교 분석하였다.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.818-823
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• 2011

6-generalized coordinates of absolute translational displacements and angular displacements measured at Cartesian coordinates system fixed at the ground has been used to describe general dynamic behavior of a rigid body in mechanical systems. However, track coordinates system moving with the centerline of the track can be used to develop dynamic formulations for railway vehicle. It is easy to impose the constraints of track coordinates by the virtue of track coordinates system moving with track centerline. In this analysis, dynamic equations of railway vehicle by using track coordinates system is derived and the simulation results are presented.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.683-690
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• 1985

본 논문에는 Euler매개변수를 회전좌표계로 사용하여 구속된 3차원 기계시스템의 역동학력 해 을 수행한 연구결과가 수록되었다. 해석을 위해 문제에 등장하는 비선형 Holonomic구속조건식 들과 운동방정식들을 Cartesian일반좌표계을 사용하여 표시하였으며, 일반좌표계를 구성하는 각 강체의 좌표계로는 변위를 나타내기 위한 3개의 좌표와 회전을 나타내기 위한 4개의 Euler매 개변수가 사용되었다. 구속조건식들과 미분방정식 형태의 운동방정식들을 결합하여 시스템 전 체의 운동방정식을 유도하기 위해 Lagrange승수 기법을 사용하였다. 각 강체의 주어진 시간에 서의 위치, 속도, 가속도는 기구학적 해석(kinematic analysis)을 통해 얻어지고, 이 자료들을 전 체운동방정식에 대입하여 Lagrnage승수의 값을 계산하여 6개의 자유도를 가진 로봇 기구를 원 하는대로 운전하는에 필요한 각 관절의 토오크를 계산하였으며, 계산결과가 정확하다는 사실이 입증되었다. 연구결과 Euler매개변수를 회전좌표로 사용할 경우 특이 경우(singular case)가 발 생하지 않으며, 이 방법은 역동력학 해석용 다목적 전산프로그램 개발에 광범위하게 응용될 수 있음이 밝혀졌다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.901-903
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• 2005

본 논문에서는 평면 상에 두 볼록집합 P와 Q가 주어졌을 때, P를 강체운동 하에서 수평 이동 및 회전이동하여 Q와 겹치는 영역이 근사적으로 최대가 되는 알고리즘을 제시한다. 임의의 양의 상수 $\epsilon$이 주어졌을 때, 본 알고리즘은 가장 많이 겹치는 넓이의 $1-\epsilon$ 배를 보장하는 P의 강체운동을 $O((1/\epsilon)$ 번의 기하 질의 와 $O((1/{\epsilon}^2)log(1/$\epsilon)) 시간 내에 구할 수 있다. 특히 P와 Q가 볼록다각형 일 때, $O((1/\epsilon)log\;n+(1/{\epsilon}^2)log(1/\epsilon))$ 시간에 구한다. 만약 수평 이동만 사용할 경우는 $O((1/\epsilon)log\;n+(1/\epsilon)log(1/\epsilon))$ 시간에 구할 수 있다.

• Journal of the Korea Computer Industry Society
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• v.10 no.5
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• pp.221-226
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• 2009

The closed system's internal rigid body particle rotation motion can be distinguished by a main body that becomes the core of the rotation and the particles that are subjected to the rotation. The instance of particles becoming bounded to the main body as a holonomic system, has till now, been well defined and formulated in the study of Kinetics, and the structure of the formulas relate well to reality. However, when the structure is non-holonomic it deviates from these existing equations. The purpose of this research is to categorize the differences between a holonomic system and a non-holonomic system when rotating, through devices. With a special emphasis on the real phenomenon of the non-holonomic system which will be formulated in the form of a model or computer simulation. With these formulas, the center of mass shift in a closed rotating motion system and confined motion of external friction will be adequately expressed, so that it may be applied to computer graphics motions methods.

• The KIPS Transactions:PartA
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• v.14A no.5
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• pp.255-262
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• 2007

Physically-based researches on simulating helicopter motions have been achieved in the field of aeronautics, aerodynamics and others. These results, however, have not been appled in the computer graphics area, mainly due to their complex equations and heavy computations. In this paper, we propose a dynamics model of helicopter rotor blades, which would be easy to implement, and suitable for real-time simulations of helicopters in the computer graphics area. Helicopters fly by the forces due to the collisions between air and rotor blades. These forces can be interpreted as the impulsive forces between the fluid and the rigid body. Based on these impulsive forces, we propose an approximated dynamics model of rotor blades, and it enables us to simulate the helicopter motions using existing rigid body simulation methods. We compute forces due to the movement of rotor blades according to the Newton's method, to achieve its real-time computations. Our prototype implementation shows real-time aerial navigation of helicopters, which are murk similar to the realistic motions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.3
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• pp.339-346
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• 2001

The impulsive spin-up flow in a shallow rectangular container is analyzed numerically by quasi 3-D unsteady laminar flow. In the non-inertia coordinates, the flow is generated by the virtual forces as Coriolis force, etc.. After the boundary layers grow up near sidewalls, primary vortexes separate from the sidewalls. As the Reynolds number increases, the subsidiary vortexes take place in the boundary layer. The rigid body rotation is started from the inner region and propagated to the outer region, finally all the fluid reaches the rigid body rotation. According to the Reynolds number and the aspect ratio, the development of vortex pattern is symmetric or asymmetric.

• Journal of Korea Multimedia Society
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• v.13 no.9
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• pp.1382-1390
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• 2010

We can see interactions between rigid body and fluid every day, anywhere. This kind of rigid body-fluid simulation is one of the most difficult problems in physically-based modeling, mainly due to heavy computations. In this paper, we present a real-time dynamics model for simulating stone skipping, which is a popular rigid body-fluid interaction in the real world. In comparison to the previous works, our improved dynamics model supports the rotation of the stones and also computes frictional forces with respect to the air. We can simulate a realistic result for various user input by using proposed model. Additionally, we present a water surface model to show more realistic ripples interactively. Our methods can be easily adapted to other interactive dynamics systems including 3D game engines.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.193-199
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• 2003

The most cultural heritages are composed of piled multi-block systems which are vulnerable to earthquakes. The stone of low height tends to slide when the excitation such as earthquake is applied and this sliding motion has effects on the whole response of the structure. In this study, analytical method of sliding motion of the piled multi-block systems considering horizontal rotation is developed and compared with shaking table test results. It is shown that the nonlinear analysis of sliding motion of multi-block system leads to satisfactory results.