• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.587-588
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• 2011

• 한국컴퓨터산업학회논문지
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• 제8권3호
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• pp.181-186
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• 2007

폐쇄된 계 내부와 외부에서 작용되는 운동에는 선형 열린 운동과 닫힌 운동이 있고 비선형 열린 운동과 닫힌 운동이 있다. 선형 닫힌 운동이 마찰과 같은 외력을 받을시 갇힌 운동이 발생된다. 회전 닫힌 운동에도 마찰과 같은 외력을 받을시 회전 갇힌 운동이 있음을 해석 한다. 회전 닫힌 운동과 갇힌 운동을 액체 실험 장치를 통하여 정량적으로 고찰하고 회전 갇힌 운동이 있음을 분석하여 회전 열린 운동, 닫힌 운동 과 갇힌 운동에 대한 컴퓨터 씨뮬레이션 수식모델을 정한다. 그리고 간단한 운동 장치의 그래픽 구조를 고려 할 수 있도록 소개한다.

• Journal of Mechanical Science and Technology
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• 제17권4호
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• pp.545-561
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• 2003

We use the first-passage-time formulation by Torquato, Kim and Cule ［J. Appl. Phys., Vol. 85, pp. 1560∼1571 (1999) ］, which makes use of the first-passage region in association with the diffusion tracer's Brownian movement, and develop a new efficient Brownian motion simulation method to compute the effective conductivity of digitized composite media. By using the new method, one can remarkably enhance the speed of the Brownian walkers sampling the medium and thus reduce the computation time. In the new method, we specifically choose the first-passage regions such that they coincide with two, four, or eight digitizing units according to the dimensionality of the composite medium and the local configurations around the Brownian walkers. We first obtain explicit solutions for the relevant first-passage-time equations in two-and three-dimensions. We then apply the new method to solve the illustrative benchmark problem of estimating the effective conductivities of the checkerboard-shaped composite media. for both periodic and random configurations. Simulation results show that the new method can reduce the computation time about by an order of magnitude.

• 한국해양공학회지
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• 제17권4호
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• pp.1-7
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• 2003

A virtual reality technology for multipurpose numerical simulation is developed to reproduce and investigate a variety of ocean environmental problems in a 3D Numerical Wave Tank(NWT). The governing equations for solving incompressible fluid motion are Navier-Stokes equation and continuity equation. The Marker-Density function technique is adopted to implement the fully nonlinear freesurface kinematic condition. The marine environmental situations, i.e., waves, currents, etc., are reproduced by use of multi-segmented wavemakers on the basis of the so-called ″snake-principle″. In this paper, some numerical reproduction techniques for regular, and irregular waves, multi-directional waves, Bull's-eye wave. wave-current, and solitary wave are presented, and a model test in motion with large amplitude of roll angle is conducted in the developed 3D-NWT, using a overlaid grid system.

• 한국소음진동공학회논문집
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• 제12권1호
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• pp.29-35
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• 2002

A simulation program for vehicle dynamic analysis was developed. The Cartesisn coordinate system was used for translational motion and the Euler angle system was used for rotational motion. A three dimensional multi-wheeled vehicle model and equations of motion were derived. Also static equilibrium analysis was added for initial vehicle condition setting. The program user can describe the exact characteristics of suspension spring force and damping force in the user subroutine. A wheel-ground contact model which represents geometrical effect was developed. Two cases of simulation for 16 D.O.F. vehicle model were conducted to validate the developed program by comparing the simulation results with the experimental data.

• 한국CDE학회논문집
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• 제14권4호
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• pp.261-270
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• 2009

We can save a lot of efforts and time to perform various kinds of multibody system dynamics simulations if the equations of motion of the multibody system can be formulated automatically. In general, the equations of motion are formulated based on Newton's $2^{nd}$law. And they can be transformed into the equations composed of independent variables by using velocity transformation matrix. In this paper the velocity transformation matrix is derived based on a topological modeling approach which considers the topology and the joint property of the multibody system. This approach is, then, used to formulate the equations of motion automatically and to implement a multibody system dynamics simulation program. To verify the the efficiency and convenience of the program, it is applied to the lifting simulation of a floating crane.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.487-488
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• 2012

• Journal of Computational Design and Engineering
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• 제3권3호
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• pp.250-265
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• 2016

Owing to our rapidly aging society, accessibility evaluation to enhance the ease and safety of access to indoor and outdoor environments for the elderly and disabled is increasing in importance. Accessibility must be assessed not only from the general standard aspect but also in terms of physical and cognitive friendliness for users of different ages, genders, and abilities. Meanwhile, human behavior simulation has been progressing in the areas of crowd behavior analysis and emergency evacuation planning. However, in human behavior simulation, environment models represent only "as-planned" situations. In addition, a pedestrian model cannot generate the detailed articulated movements of various people of different ages and genders in the simulation. Therefore, the final goal of this research was to develop a virtual accessibility evaluation by combining realistic human behavior simulation using a digital human model (DHM) with "as-is" environment models. To achieve this goal, we developed an algorithm for generating human-like DHM walking motions, adapting its strides, turning angles, and footprints to laser-scanned 3D as-is environments including slopes and stairs. The DHM motion was generated based only on a motion-capture (MoCap) data for flat walking. Our implementation constructed as-is 3D environment models from laser-scanned point clouds of real environments and enabled a DHM to walk autonomously in various environment models. The difference in joint angles between the DHM and MoCap data was evaluated. Demonstrations of our environment modeling and walking simulation in indoor and outdoor environments including corridors, slopes, and stairs are illustrated in this study.

• 한국항공우주학회지
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• 제34권5호
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• pp.19-29
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• 2006

본 연구에서는 비행중인 유도무기의 기체분리에 대한 수치적 해석을 수행하였다. 기체의 정확한 분리운동을 모사하기 위해 삼차원 공간에서 각각의 물체가 연결되어 움직이는 6자유도 운동방정식을 유도하였으며, 물체를 둘러싼 격자계의 독립적인 처리를 위해 개발된 비정렬 중첩격자기법과 연계하였다. 개발된 해석기법은 유도무기의 받음각이 0도와 5도인 경우의 기체분리운동 해석에 적용되었으며, 이를 통해 본 연구에서의 해석기법이 다중 물체간의 상대운동이 있는 비정상 유동장을 해석하는데 효과적임을 알 수 있었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권3호
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• pp.318-328
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• 2018

Disk type underwater gliders are a new type of underwater gliders and they could glide in various directions by adjusting the internal structures, making a turnaround like conventional gliders unnecessary. This characteristic of disk type underwater gliders makes them have great potential application in virtual mooring. Considering dynamic models of conventional underwater gliders could not adequately satisfy the motion characteristic of disk type underwater gliders, a nonlinear dynamic model for the motion simulation of disk type underwater glider is developed in this paper. In the model, the effect of internal masses movement is taken into consideration and a viscous hydrodynamic calculation method satisfying the motion characteristic of disk type underwater gliders is proposed. Through simulating typical motions of a disk type underwater glider, the feasibility of the dynamic model is validated and the disk type underwater glider shows good maneuverability.