• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.1
• /
• pp.154-161
• /
• 1997

This paper presents the method to eliminate the constraint reaction in the Lagrange multiplier form equation of motion by using a generalized coordinate driveder from the velocity constraint equation. This method introduces a matrix method by considering the m dimensional space spanned by the rows of the constraint jacobian matrix. The orthogonal vectors defining the constraint manifold are projected to null vectors by the tangential vectors defined on the constraint manifold. Therefore the orthogonal projection matrix is defined by the tangential vectors. For correcting the generalized position coordinate, the optimization problem is formulated. And this correction process is analyzed by the quasi Newton method. Finally this method is verified through 3 dimensional vehicle model.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.4
• /
• pp.543-547
• /
• 2005

The Belousov-Zhabotinskii system measured by a Pt electrode is investigated under external electrode current constraint. A dynamical analysis of the electrode reaction phase has been made by means of a linearized stability criterion valid for three-variable system. It turns out that limit cycle oscillatory regime and dynamical behaviors of the electrode reaction phase have been degenerated under periodical electrode current.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.4D
• /
• pp.671-678
• /
• 2006

In this study, to describe vehicle-structure dynamic interaction phenomena with 1/4 vehicle model, nonlinear Hertzian contact spring and nonlinear contact damper are adopted. The external loads acting on 1/4 vehicle model are selfweight of vehicle and geometry information of running surface. The constraint equation on contact surface is implemented by the Penalty method with stabilization and the reaction from constraint violation. To describe pitching motion of various vehicles two types of the displacement constraint equations are exerted to connect between car bodies and between bogie frames, i.e., the rigid body connection and the rigid body connection with pin, respectively. For the time integration of dynamic equations of vehicles and structure Newmark time integration scheme is adopted. To reduce the error caused by inadequate time step size, adaptive time-stepping technique is also adopted. Thus, it is expected that more versatile dynamic interaction phenomena can be described by this approach and it can be applied to various railway dynamic problems with low computational cost.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.2
• /
• pp.185-191
• /
• 2001

In many papers, the powertrain system generally has been madeled as one-dimensional torque model. One-dimensional powertrain model may calculate the torque correctly but it does not consider the non-rotational degrees-of-freedom of the powertrain components and the interaction of these degrees-of-freedom with the vehicle body frame and suspension. To consider the non-rotational degrees of freedom, the differential is modeled as a three-dimensional rigid body in this paper. A constant velocity joint is newly formulated and a relative constraint is also formulated to model the motion transfer due to gear ratio of the differential. Implementing the proposed powertrain system in the multibody model, more detail dynamic responses can be obtained. Obtained outputs such as reaction torques on the constant velocity joint and reaction forces on the rack can be useful data in the design of a powertrain.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.191-196
• /
• 2005

In this study, to describe vehicle-track-bridge dynamic interaction phenomena with 1/4 vehicle model, nonlinear Hertzian contact spring and nonlinear contact damper are introduced. In this approach external loads acting on 1/4 vehicle model are self weight of vehicle and geometry information of running surface. The constraint equation on contact surface is implemented by Penalty method. Also, to improve the numerical stability and to maintain accuracy of solution, the artificial damper and the reaction from constraint violation are introduced. A nonlinear time integration method, in this study, Newmark method is adopted for both equations of vehicles and structure. And to reduce the error caused by inadequate time step size, adaptive time-stepping technique is partially introduced. As the nonlinear Hertzian contact spring has no resistance to tensile force, the bouncing phenomena of wheelset can be described. Thus, it is expected that more versatile dynamic interaction phenomena can be described by this approach and it can be applied to various railway dynamic problems.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.8 no.1
• /
• pp.1-7
• /
• 2012

A PHE (Process Heat Exchanger) is a key component required to transfer heat energy of $950^{\circ}C$ generated in a VHTR (Very High Temperature Reactor) to the chemical reaction that yields a large quantity of hydrogen. A small-scale PHE prototype made of Hastelloy-X is being tested in a small-scale gas loop at Korea Atomic Energy Research Institute. In order to properly evaluate the high-temperature structural integrity of the small-scale PHE prototype, it is very important to impose a proper constraint condition on its structural analysis model. For this effort, we tried to impose several constraint conditions on the structural analysis model and consequently fixed a proper and effective displacement constraints.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.1
• /
• pp.223-235
• /
• 1993

VTR(Video Tape Recorder) has very complicated mechanisms composed of various cams, links, gears and so on. To satisfy kinematic requirements of VTR components, various geometric constraints between rigid bodies and a translational cam design program are developed. Mechanisms of VTR are divided into functional groups like a control part, a loading part and a tape guide part. Each group is modeled for kinematic and dynamic analysis. Finally, all groups are combined together for a complete VTR model and loads required for each function of VTR controls are studied. Detailed description of developed programs are presented and result are discussed.

• Journal of Astronomy and Space Sciences
• /
• v.17 no.2
• /
• pp.309-316
• /
• 2000

KOMPSAT-2 will carry MSC(Multi-Spectral Camera) which provides 1m resolution panchromatic and 4m resolution multi-spectral images at the altitude of 685km sun-synchronous mission orbit. The mission operation of KOMSPAT-2 is to provide the earth observation using MSC with nadir pointing. KOMPSAT-2 will also have the capability of roll/pitch tilt maneuver using reaction wheel of satellite as required. In order to protect MSC from thermal distortion as well as direct sunlight, MSC shall be operated within the constraint of sun incidence angle. It is expected that the sunlight will not violate the constraint of sun incidence angle for normal mission operations without roll/pitch maneuver. However, during roll/pitch tilt operations, optical module of MSC may be damaged by the sunlight. This study analyzed sun incidence angle of payload using KOMPSAT-2 AOCS (Attitude and Orbit Control Subsystem) Design and Performance Analysis Soft ware for KOMPSAT-2 normal mission operations.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.5
• /
• pp.362-368
• /
• 2014

Container vessel sizes have constantly increased over the past two decades. With increasing ship sizes and higher container loading capacities, the adoption of lashing bridges has also increased. Today's lashing bridge designs range from 1st tier to 3rd tier lashing bridges. Container securing program of the past which is based on two lashing rods and 1st tier lashing bridge has to be improved to be suitable for the present time. The equilibrium equations in this study are established to cover the application of 3~4 lashing rods and 2nd~3rd tier lashing bridges. In addition developed program is improved to be able to calculate the reaction forces and optimum arrangement under the external lashing. An optimization algorithm which is suitable for the container securing problems involved the equality constraint has been also adopted in this study.

• International Journal of Precision Engineering and Manufacturing
• /
• v.6 no.4
• /
• pp.21-25
• /
• 2005

In the dynamic analysis of a mechanism, if one or more of the components are flexible, then the simulation will not be accurate because of the violation of the rigid body assumption. Mode shapes are used to represent the dynamic behavior of an elastic structure. A modal synthesis method which uses a combination of normal modes, constraint modes, and attachment modes, was used to represent effectively the elastic deformation of a flexible multibody. Since the combination of these modes should be different for each type of connecting part, the modal synthesis method was studied for the various types of interconnecting joints. In addition, the analysis procedure for the flexible body was explained. A satellite system with flexible solar panels was chosen as an example to show the effectiveness of the proposed method.