• 대한의용생체공학회:의공학회지
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• 제25권4호
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• pp.277-282
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• 2004

자동차 충돌 시 신체의 크기가 작은 여성 승객의 거동 및 상해 기구를 조사하기 위하여 5% percentile의 여성 유한 요소 모델을 개발하였다. 본 모델은 작은 신체 여성의 형상을 대표하는 분절된 강체와 해부학적으로 상세하게 묘사된 내부 요소들로 구성되어 진다. 분절된 강체 모델은 상세한 골격 및 장기 등의 플랫폼 역할을 수행하며 또한 작은 여성 승객의 전체적인 운동역학을 표현하기도 한다. 본 논문에서는 분절된 강체 모델의 체형 구성 및 유한요소 구조 등에 대한 자세한 내용이 모델의 검증과 함께 소개되어 진다. 모델링의 후반부 즉 작은 여성의 해부학적으로 상세한 내부 요소는 연이은 part II 논문에서 다루게 된다.

• 한국군사과학기술학회지
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• 제3권2호
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• pp.15-22
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• 2000

Shock and vibration characteristics of a tractor-trailer type vehicle system with air suspension and air coupler running on a single bump road are investigated. The vehicle system is modelled and solved to two types of models, i.e. rigid-multi-body and flexible-multi-body model, by ADAMS and NASTRAN software. And the shock impulse is given by a single bump model on the road. When the analysis results of the rigid-multi-body model is compared with those of the flexible-multi-body model, it is revealed that the vibration and accelerations of the latter model are more repetitive and larger than the former.

• 한국정밀공학회지
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• 제15권11호
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• pp.100-107
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• 1998

This paper presents the development of estimation model and control method based on the new robot vision. This proposed control method is accomplished using the sequential estimation scheme that permits placement of the rigid body in each of the two-dimensional image planes of monitoring cameras. Estimation model with six parameters is developed based on the model that generalizes known 4-axis scara robot kinematics to accommodate unknown relative camera position and orientation, etc. Based on the estimated parameters, depending on each camera the joint angle of robot is estimated by the iteration method. The method is experimentally tested in two ways, the estimation model test and a three-dimensional rigid body placement task. Three results show that control scheme used is precise and robust. This feature can open the door to a range of application of multi-axis robot such as assembly and welding.

• 한국멀티미디어학회논문지
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• 제12권2호
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• pp.323-328
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• 2009

게임이나 가상현실 등에서 사용자들에게 사실성과 몰입 감을 주기 위해서 자연 현상들을 시뮬레이션하고 있다. 게임이나 가상현실에서 물이나 바다와 같은 유체를 3차원으로 시뮬레이션 하는데 있어서 중요한 요소는 실시간 처리와 사실성이다. 유체 모델은 특정 상황에 따른 다양한 방정식과 많은 파라미터 값에 의해 제어되기 때문에 시뮬레이션 하는데 많은 어려움이 따른다. 또한 복잡한 물리 수식을 기반으로 하기 때문에 유체 모델을 시뮬레이션하기 위해서는 많은 수행 시간이 소요된다. 본 논문에서는 실시간 유체와 강체(rigid body) 사이의 상호작용을 표현하기 위해 간략화 된 유체 표면 모델(Fluid-Surface Model)을 제안하고, 개선된 계산과정을 통해 보다 빠르게 시뮬레이션 하도록 한다. 또한 본 논문에서는 유체의 표면과 강체의 상호작용을 표현하는데 있어서 유체의 항력에 의해서 강체와 충돌 시 발생하는 유체 표면의 움직임을 나타낸다. 본 논문에서 제안하는 자연스러운 유체 표면 모델은 유체역학적 방법을 사용하여 실시간에 사실적으로 표현된다. 그리고 이러한 유체 표면 모델을 PC 환경에서 사용자와 상호작용 가능하도록 재현하여, 게임이나 애니메이션에서의 유체 모델들에도 적용할 수 있다.

• Journal of Computational Design and Engineering
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• 제1권2호
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• pp.96-102
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• 2014

In the field of design and manufacturing, there are many problems with managing dynamic states of three-dimensional (3D) objects. In order to solve these problems, the four-dimensional (4D) mesh model and its modeling system have been proposed. The 4D mesh model is defined as a 4D object model that is bounded by tetrahedral cells, and can represent spatio-temporal changes of a 3D object continuously. The 4D mesh model helps to solve dynamic problems of 3D models as geometric problems. However, the construction of the 4D mesh model is limited on the time-series 3D voxel data based method. This method is memory-hogging and requires much computing time. In this research, we propose a new method of constructing the 4D mesh model that derives from the 3D mesh model with continuous rigid body movement. This method is realized by making a swept shape of a 3D mesh model in the fourth dimension and its tetrahedralization. Here, the rigid body movement is a screwed movement, which is a combination of translational and rotational movement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1114-1119
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• 1995

This paper presents the development of estimation model and control method based on the new computer vision. This proposed control method is accomplished using a sequential estimation scheme that permits placement of the rigid body in each of the two-dimensional image planes of monitoring cameras. Estimation model with six parameters is developed based on a model that generalizes known 4-axis scara robot kinematics to accommodate unknown relative camera position and orientation, etc. Based on the estimated parameters,depending on each camers the joint angle of robot is estimated by the iteration method. The method is tested experimentally in two ways, the estimation model test and a three-dimensional rigid body placement task. Three results show that control scheme used is precise and robust. This feature can open the door to a range of application of multi-axis robot such as assembly and welding.

• Advances in aircraft and spacecraft science
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• 제10권5호
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• pp.419-437
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• 2023

This paper presents the study of the effects of rigid-body motion simultaneously with the presence of the effects of temporal variation due to the existence of morphing speed on the aeroelastic stability of the two-stage telescopic wings, and hence this is the main novelty of this study. To this aim, Euler-Bernoulli beam theory is used to model the bending-torsional dynamics of the wing. The aerodynamic loads on the wing in an incompressible flow regime are determined by using Peters' unsteady aerodynamic model. The governing aeroelastic equations are discretized employing a finite element method based on the beam-rod model. The effects of rigid-body motion on the length-based stability of the wing are determined by checking the eigenvalues of system. The obtained results are compared with those available in the literature, and a good agreement is observed. Furthermore, the effects of different parameters of rigid-body such as the mass, radius of gyration, fuselage center of gravity distance from wing elastic axis on the aeroelastic stability are discussed. It is found that some parameters can cause unpredictable changes in the critical length and frequency. Also, paying attention to the fuselage parameters and how they affect stability is very important and will play a significant role in the design.

• Structural Engineering and Mechanics
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• 제82권4호
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• pp.503-515
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• 2022

The multi-rigid-body matrix method (MRBMM) is a generalized modeling method for obtaining the displacements, forces, and dynamic characteristics of a compliant mechanism without performing inner-force analysis. The method discretizes a compliant mechanism of any type into flexure hinges and rigid bodies by implementing a multi-body mass-spring model using coordinate transformations in a matrix form. However, in this method, the deformations of bodies that are assumed to be rigid are inherently omitted. Consequently, it may yield erroneous results in certain mechanisms. In this paper, we present a multi-compliant-body matrix-method (MCBMM) that considers a rigid body as a compliant element, while retaining the generalized framework of the MRBMM. In the MCBMM, a rigid body in the MRBMM is segmented into a certain number of body nodes and flexure hinges. The proposed method was verified using two examples: the first (an XY positioning stage) demonstrated that the MCBMM outperforms the MRBMM in estimating the static deformation and dynamic mode. In the second example (a bridge-type displacement amplification mechanism), the MCBMM estimated the displacement amplification ratio more accurately than several previously proposed modeling methods.

• 소음진동
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• 제3권3호
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• pp.231-243
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• 1993

The dynamic characteristics of two types of mathematical models for a rigid body suspension system are analyzed and compared in this paper. One is a linearized model which is commonly used in the engine mount system analysis, the other is a nonlinear model which usually applied to the pendulum type system. The typical 3 d.o.f's mathematical model, for convenience, is chosen as a simulation model, because it has fundamental dynamic characteristics of suspension system. Time responses and unbalance responses of the rigid body, transmitted forces and torques are simulated by using the mathematical model. From the results of computer simulation, it is approved that he nonlinear model is valid and the linearized model gives erroneous results in the case of the pendulum type suspension system. In addition, in this study the effects of design change on the dynamic characteristics of the suspension system are investigated. Mount locations, mount angles, lengths, stiffness and damping coefficients of suspension bars are chosen as design parameters.

• 한국정밀공학회지
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• 제15권3호
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• pp.150-156
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• 1998

In this paper, a 3-DOF(Degree Of Freedom) rigid body model is developed for dynamic analysis of a hydrostatic table. The dynamic coefficients, stiffness and damping constant of each pad are calculated from the mass flow continuity condition. The validity of this model is examined in theoretical and experimental method. The dynamic behavior when mass unbalances and local variations of stiffness and damping of pads present is analyzed for real applications of hydrostatic table. Since the theoretical and experimental results show goof agreement. it can be said that the 3-DOF rigid body model is useful for the dynamic model of the table. The analysis reveals that the pitching motion is the dominant mode of vibration, It also reveals that unbalanced loads can increase amplitude of tilting motion and reduce natural frequencies and damping capacity of the hydrostatic table.