• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.112-119
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• 2001

Design sensitivity is an important is an important device in improving a mechanical system design. A continuum design consists of the shape and orientation design. This research develops the shape and orientation design sensitivity method. The configura-tion design variables of multibody systems define the shape and orientation changes. The equations of motion are directly differentiated to obtain the governing equations for the design sensitivity. The governing equation of the design sensitivity is formulated as an over determined differential algebraic equation and treated as ordinary differential equations on mani-folds. The material derivative of a domain functional is performed to obtain the sensitivity due to shape and orientation changes. The configuration design sensitivities of a fly-ball governor system and a spatial four bar mechanism are obtained using the proposed method and are validated against those obtained from the finite difference method.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.47-54
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• 2006

To improve passenger safety, seat belt systems with pre-tensioner that tightens seat belt webbing using explosive just before collision are widely used these days. Even though seatbelt must not unlatched without passengers' operation. explosive power of pre-tensioner can cause unlocking of a buckle. To prevent the unlocking, an anti-g mass that blocks displacement of the release button has been attached to the buckle. In this study, the dynamics and statics of locking mechanism associated with operation of anti-g buckle has been theoretically investigated, and important design variables that affect the operation of anti-g buckle have been identified. Through the total seat belt system's dynamic simulation using force and displacement inputs obtained from seat belt sled test, design of the proposed anti-g buckle has been validated.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.99-108
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• 2005

This paper represents an efficient modeling method of a suspension system for the vehicle dynamic simulation. The suspension links are modeled as composite joints. The motion of wheel is defined as relative one degree of freedom motion with respect to car body. The unique relative kinematic constraint formulation between the car body and wheel enables to derive equations of motion in terms of wheel vertical motion. Thus, vehicle model has ten degrees of freedom. By using velocity transformation method, the equations of motion of the vehicle is systematically derived without kinematic constraints. Various vehicle simulation such as J-turn, slowly increasing steer, sinusoidal sweep steer and bump run has been performed to verify the validity of the suggested vehicle model.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.4
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• pp.80-90
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• 1994

Basic constraint equations derived from orthogonality conditions between a pair of body-fixed vectors and a body-fixed vector or a vector between two bodies are reformulated by using relative coordinate kinematics between two adjacent reference frames. Arithmetic numbers of operations required to compute derivatives of the constraint equations are drastically reduced. A mixed formulation of relative and cartesian coordinates is developed to further simplify derivatives of the constraints. Advantages and disadvantages of the new formulation are discussed. Possible singularity problem of para llelism constraints is resolved by introducing an extra generalized coordinate. Kinematic analysis of a McPherson strut suspension system are carried out to illustrate use and efficiency of the new formulation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.6
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• pp.1265-1272
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• 1988

Kinematic and dynamic equations of open-loop mechanical systems are derived using the velocity transformation. The velocities of a link are defined by the velocities of the previous link and relative velocities between the links. The velocities and angular velocities are expressed with joint velocities and 6*1 velocity transformation vector. Using the velocity relations, recursive formula are derived and compared to the previous results. The derived recursive formula are modified and applied to the dynamic simulation of a vehicle. The computational efficiency of the vehicle simulation with the derived recursive formula is much enhanced.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.09a
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• pp.155-159
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• 2005

High speed presses with high resolution in semiconductor lead frame manufacturing process are needed . But high speed operation accompanies mechanical vibration. therefore optimized kinematic structure to minimize vibration is required for a high speed press. And the growing competition in the industry asks a press with low cost, high speed, high resolution, and high pressing force, For this purpose a high speed press was modeled with 3D CAD solid modeling system and dynamic analysis were performed with CAE S/W for multibody dynamic analysis, Through these analyses a motor appropriate to a high speed press was selected and link structure for feeding system of the press was modified to reduce vibration. To perform this analysis working Model which is 2D kinematics and dynamic analysis software was used.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.105-111
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• 1999

The paper presents development of a Hardware-In-the-Loop simulation (HILS) system for the purpose of testing performance, stability, and reliability of an electronic power steering system(EPS). In order to realistically test an EPS by the proposed HILS apparatus, a simulated uniaxial dynamic rack force is applied physically to the EPS hardware by a pnumatic actuator. An EPS hardware is composed of steering wheel &column, a rack & pinion mechanism, andas motor-driven power steering system. A command signal for a pneumatic rack-force actuator is generated from the vehicle handling lumped parameter dynamic model 9software) that is simulated in real time by using a very fast digital signal processor. The inputs to the real-time vehicle dynamic simulation model are a constant vehicle forward speed and from wheel steering angles driven through a steering system by a driver. The output from a real-time simulation model is an electric signal that is proportional to the uniaxial rack force. The vehicle handling lumped parameter dynamic model is validated by a fully nonlinear constrained multibody vehicle dynamic model. The HILS system simulation results sow that the proposed HILS system may be used to realistically test the performance stability , and reliability of an electronic power steering system is a repeated way.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1571-1578
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• 2013

With the emergence of high-integration array and large area panel process, the need to minimize the generation of particles in the field of semiconductor, LCD and OLED has grown. As an alternative to the conventional roller system, a contactless magnetic conveyor has been proposed to reduce the generation of particles. An EM-PM hybrid which is one of magnetic levitation types is already proposed for the conveyor system. One of problems pointed out with this approach is the vibration caused by the dynamic interaction between conveyor and rail. To reduce the vibration, the introduction of a secondary suspension system which aims to decouple the levitation electromagnet from the main body is proposed. The objective of this study is to develop a dynamic model for the magnetically levitated conveyor, and to investigate the effect of the introduced suspension system. An integrated model of levitation system and rail based on 3D multibody dynamic model is proposed. With the proposed model, the dynamic characteristics of maglev conveyor system are analyzed, and the effect of the secondary suspension and the stiffness and damping are investigated.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.47-55
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• 2012

This work deals with dynamic analysis of a monorail system with magnetic caterpillar where magnets are embedded inside each articulated element of the caterpillar, augmenting traction force of main rubber wheels to climb up slope up to 15 degree grade. Considerations are first given to determine stiffness of the primary and secondary suspension springs in order for the natural frequencies of car body and bogie associated with vertical, pitch, roll and yaw motion to be within generally accepted range of 1-2 Hz. Equations for calculating magnetic force needed to climb up given slope are derived, and a magnetic caterpillar system for 1/6 scale monorail is designed based on the derivation. To assess the hill climbing ability and cornering stability, and make sure smooth operation of the side and vertical guiding wheels which is critical for safety, a multibody model that takes into account of every component level design characteristics of car, bogie, and caterpillar is set up. Through hill climbing simulation and comparison with measurement of the limit slope, the validity of the analysis and design of the magnetic caterpillar system are demonstrated. Also by studying the curving behavior, maximum curving speed without rollover, functioning of lateral motion constraint system, the effects of geometry of guiding rails are studied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.507-510
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• 2005

Brake judder, which occurs when brakes are suddenly applied to a vehicle driving at high speed, affects the driver's safety to a great extent. It also has a low frequency that drivers can easily feel. Among theses presented, none offered studies using modeling of actual brakes in computer simulation in order to recreate the brake judder phenomenon, and most of them directly applied the frequency generated by the judder. To resolve this issue, this study hopes to develop a computer model that can recreate the phenomenon of brake judder. In this paper, in order to examine the vibration problem occurring when brake is applied on the test car, the multibody dynamic analysis program ADAMS was used to develop a computer model that can recreate the actual braking mechanism while breaking away from the existing understanding of brakes. Thus the existence of the brake judder phenomenon due to DTV(Dist Thickness Variation) and wheel rotating speed was examined through the developed model.