• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.78-85
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• 2011

The Vortex-In-Cell(VIC) method combined with panel method is applied to the analysis of incompressible unsteady viscous flow. The dynamics of resulting flow is governed by the vorticity transport equation in Lagrangian form with vortex particle representation of the flow field. A regular grid which is independent to the shape of a body is used for numerical evaluation based on immersed boundary technique. With an introduction of this approach, the development and validation of the VIC method is presented with some computational results for incompressible viscous flow around two or three dimensional bodies such as wing section, sphere, finite wing and marine propeller.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.33-38
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• 2008

Numerical investigation of asymmetric vortices at high angles of attack subsonic flow is performed using three-dimensional Navier-Stokes equations. A small bump has been carefully selected and attached near the nose of an ogive cylinder to simulate symmetric vortices. Selected bump shape does develop asymmetric vortices and is verified using Lamont's experimental results. By changing the angle of attack, Reynolds numbers, and Mach numbers, the characteristics of asymmetric vortices are observed. The angle of attack which contributes significantly to the generation of asymmetric vortices are over 30 degrees. By increasing Mach number and Reynolds number asymmetric vortices, hence the side forces show decreasing trend..

• 대한기계학회논문집A
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• 제31권8호
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• pp.889-895
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• 2007

Quantifying dynamic stability is important to assessment of falling risk or functional recovery for leg injured people. Human locomotion is complex and known to exhibit nonlinear dynamical behaviors. The purpose of this study is to quantify major joints of the body using chaos analysis during walking. Time series of the chaotic signals show how gait patterns change over time. The gait experiments were carried out for ten young males walking on a motorized treadmill. Joint motions were captured using eight video cameras, and then three dimensional kinematics of the neck and the upper and lower extremities were computed by KWON 3D motion analysis software. The correlation dimension and the largest Lyapunov exponent were calculated from the time series to quantify stabilities of the joints. This study presents a data set of nonlinear dynamic characteristics for eleven joints engaged in normal level walking.

• 한국가시화정보학회지
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• 제10권1호
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• pp.55-59
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• 2012

Reverse Design(RD) plays an important role in simulation engineering, such as CFD (Computational Fluid Dynamics) and Virtual Engineering and Design. RD becomes much more valuable when there is no shape data of the practical models for CFD grid generations. In this study, two-camera based rapid prototyping(RP) system is proposed. 3D-PTV based measurement algorithm was adopted. The developed system was applied to reconstruct three-dimensional data of a human face, a motorcycle model, a cylindrical body and a triangular pyramid.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.341-345
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• 1996

This paper presents the dynamics and the teal-time control of a horizontally rotating inverted pendulum. The dynamic equations representing three degrees of freedom rigid body motion of the pendulum are derived, and the state feedback controller is applied to the motion control of the pendulum. A 32 bit counter board with 16 bit hardware communication ability is developed to improve the real-time control performance and is applied to a horizontally rotating inverted pendulum. The simulation and experimental studies are conducted to evaluate the performance of the developed pendulum system and the timing in the real-time control is analyzed.

• International Journal of Safety
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• 제5권1호
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• pp.10-16
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• 2006

A suspended hemispherical silicon asperity moving over a silicon plate was simulated. The simulation results on friction and wear in the interface between the two can help obtain more durable miscroscale structures. Silicon structures were constructed with Tersoff three-body potential. Dependence of friction and wear of the asperity on both the atomic arrangement in the plate and the moving direction was investigated under the condition that the asperity is subject to the attractive normal force due to the plate. The results show that the variation of friction force with the movement of asperity, and the occurrence of adhesive wear are attributed to the formation and rupture of asperity, junction between the asperity and the plate. The friction force and wear are smaller when the asperity is incommensurate with the plate, and they also depend on the moving direction of the asperity over the plate.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.881-886
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• 2004

This paper presents the inverse dynamic analysis of the wheel loader manipulator based on the experimental data. A three dimensional rigid multi-body model of the wheel loader manipulator was built up. The inverse dynamic analysis for the typical operation mode was carried out by the ADAMS program. In order to verify the analysis result with the measured one, the hydraulic pressure and displacements of the cylinders were measured and the inverse dynamic analysis was carried out using experimental data. From the results of the analysis and measurement, it was concluded that the computational driving force showed good agreement with the measured one.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권2호
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• pp.170-179
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• 2018

This paper introduces a new method to study the hydroelastic behavior of hinged Very Large Floating Structures (VLFSs). A hinged two-module structure is used to confirm the present approach. For each module, the hydroelasticity theory proposed by Lu et al. (2016) is adopted to consider the coupled effects of wave dynamics and structural deformation. The continuous condition at the connection position between two adjacent modules is also satisfied. Then the hydroelastic motion equation can be established and numerically solved to obtain the vertical displacement, force and bending moment of the hinged structure. The results calculated by the present new method are compared with those obtained using three-dimensional hydroelasticity theory (Fu et al., 2007), which shows rather good agreement.

• Advances in aircraft and spacecraft science
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• 제10권5호
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• pp.457-471
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• 2023

The paper evaluates the aerodynamic coefficients on a blunt-nose re-entry capsule with a conical cross-section followed by a cone-flare body. A computer code is developed to solve three-dimensional compressible inviscid equationsfor flow over a Space Recovery Experiment (SRE) configuration at different flare-cone half-angle at Mach 6 and angle of attack up to 5°, at 1° interval. The surface pressure variation is numerically integrated to obtain the aerodynamic forces and pitching moment. The numerical analysis reveals the influence of flare-cone geometry on the flow characteristics and aerodynamic coefficients. The numerical results agree with wind tunnel results. Increase of cone-flare angle from 25° to 35° results in increase of normal force slope, axial forebody drag, base drag and location of centre of pressure by 62.5%, 56.2% and 33.13%, respectively, from the basic configuration ofthe SRE of 25°.

• 한국기계가공학회지
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• 제17권3호
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• pp.109-119
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• 2018

The purpose of this study is to evaluate the structural safety of the front-end loader for the 90 kW class of agricultural tractors in impact test conditions. Deformation and stress on the loader under the impact test conditions are analyzed using the commercial finite element analysis software ANSYS. In previous research dealing with the initial design of the loader, the maximum stress occurred in the mount and exceeded the yield strength of the material. In this paper, an improved design of the mount of the loader was proposed to reduce the stress concentration in the initial design. The safety of the improved design was verified by performing rigid-body dynamics analysis, transient structural analysis, and static structural analysis under three impact test conditions: a drop and catch test, a corner pull test, a corner push test. It was found that the local stress concentration in the mount that appeared in the initial design was greatly reduced in the improved design, and that the maximum stresses occurred in the three impact test conditions are smaller than the yield strength. It is expected that the design improvement of the mount proposed in this study and the method of analysis may be effectively used to enhance structural safety in the development of new model front loaders in the future.