• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.71-78
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• 2011

A kart is a vehicle without the suspension system and the differential gear. The kart frame as an elastic body plays the role of a spring. By the cornering of a kart, rolling, pitching and twisting motions are induced in the kart frame. Also the slip or noncontact of the wheel and a permanent deformation of the kart frame can be induced. In order to examine closely this phenomenon, measurement on height-displacements with various sensors and tracking system and analysis on the kart frame twisting characteristics with the rolling and pitching angle are needed. According to the measurement result, while driving in a curve at high speed the kart frame is quite twisted. Analysis on the measurement results shows that a kart used primarily in high speed requires a frame with low torsional stiffness and a frame material with high tensile strength and large elongation.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.539-544
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• 2004

This paper discusses the measurement of tire driving performance for 2 types of tire model. Tire is almost composed of rubber, and this is related with the bearing capacity of tire due to the external force. In this study, an explicit time integration method has been used to simulate steady state rolling along a straight path and over a cleat. And analysis for tire dynamic response rolling over a cleat is importnat to study automobile NVH properties. Besides, the evaluation of contact shear force is perfomed for steady state rolling and braking state. The results show that there are noticeable differences between 205/60R15 and 225/60R15 tire model.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.20-26
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• 1997

A System for reducing vehicle body roll by active control is developed. The stabilizer bar with hydraulic rotary actuator produces anti-roll moment which suppresses roll tendency. This reduction of roll improves the driving safety as well as the ride comfort. Vehicle test data shows considerable reduction of roll angle during steady-state turning. Also improvement of ride comfort is achieved by making the actuator freely rotatable, i.e. by connecting all chambers of actuator in normal driving conditions. A control algorithm using steering wheel angle and vehicle speed signal as input valve is applied. It is compared with signal of the G-sensor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.693-696
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• 2007

In this paper, vibration sources of an electric forklift are identified and the forklift vibrations are reduced by structural modification by using the finite element analysis. From some experiments, it is also found that resonances occur because the natural frequencies of the forklift exist in usual driving speed range. To vibration sources of the electric forklift, the modeling is designed by using a commercial 3D CAD program CATIA and the finite element model is designed by a using finite element analysis program ANSYS which can perform modal analysis of flexible mode. To shift the natural frequencies out side the driving speed range, the frame part, the connection parts between main body and loader are modified to increase stiffness. It is verified that considerable amount of vibration are reduced by the structural modification.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.641-645
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• 2008

In this paper, vibration sources of the BLOC motor are identified and the motor vibrations are reduced by structural modification. For vibration characteristic identification, vibration signals measured by an accelerometer when the BLOC motor is moving. These signals are presented in a waterfall plot in order to find the dependency of frequency components on the motor speed. It is found that main vibration source is BLOC motor test rig. From finite element analyses and some experiments, it is also found that resonances occur because the natural frequencies of the test rig exist in usual driving speed rang. To shift the natural frequencies outside the driving rang, the test rig is modified increase stiffness. It is verified that considerable amount of vibration are reduced by the structural modification.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1660-1663
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• 2005

Unwanted vibrations are inevitably induced in other directions when pure unidirectional vibration motion is desired for the vertical scratching mechanism. Pure vertical vibration motion of the scratching machine can be obtained by driving identical two motors with symmetrically positioned eccentric unbalance masses. The desired optimal condition for driving pure vertical vibration for the scratching machine is assumed to be the resonance condition in that direction. Imposing the flexibility of the scratching machine in the horizontal direction, we can find out the amount of horizontal vibration component while maintaining the resonance in vertical direction. The desired stiffness in horizontal direction which produces the minimum vibration in horizontal direction are defined which can be used as a guide line to design the supporting structure of the scratching machine.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.1
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• pp.132-138
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• 1999

This paper addresses an analytical approach to the mechanical error analysis of gear train and tolerance design and manufacture of gear train in restricted space considering motor driving torque, driving system inertia, motor acceleration, motor rotor inertia and friction torque. The gear train is designed to have optimum gear ratio in restricted space and each gear is manufactured to have the lowest weight and each gear tooth is heat-treated to have robustness. Based on the small difference between the mechanical error analysis and measurement, gear train design with optimum gear ratio and restricted space and robustness is proposed

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.144-149
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• 2008

In this paper, vibration sources of a car-holder are identified and the car vibrations are reduced by structural modification. For vibration identification, vibration signals are measured by an accelerometer when the car is moving. From some experiments and finite element analyses, it is also found that resonances occur because the natural frequencies of the car exist in usual driving speed range. To shift the natural frequencies outside the driving speed range, the connection part is modified to increase stiffness. It is verified that considerable amount of vibration are reduced by the structural modification.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1145-1151
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• 2007

In this paper, vibration sources of an electric forklift are identified and the forklift vibrations are reduced by structural modification. For vibration identification, vibration signals are measured by an accelerometer when the forklift is moving. These signals are presented in a waterfall plot in order to find the dependency of frequency components on the forklift speed. It is found that main vibration source is tire pattern excitation. From some experiments and finite element analyses, it is also found that resonances occur because the natural frequencies of the forklift exist in usual driving speed range. To shift the natural frequencies outside the driving speed range, the connection parts between main body and loader are modified to increase stiffness. It is verified that considerable amount of vibration are reduced by the structural modification.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.195-200
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• 2013

Road loads data are indispensable in the evaluation of BSR (Buzz, Squeak, and Rattle) of automotive parts/modules. However, there are uncertainties on the best measurement locations for representative body motion and for seat systems. In the present study, we measure road loads at four different locations of a body. A-pillars on the driver and passenger sides and left and right frame fronts of the front passenger seat mountings are selected to study the acceleration behavior at different locations. The measurements are conducted with passenger cars driving local roads at 50km/hr. The measured time-acceleration data are then transformed into PSD (power spectral density) data to compare the characteristics of local accelerations. By defining the deviated acceleration components from rigid body motion, the stiffness of vehicle body could be simply expressed in a quantitative basis. Measured data from two different vehicles are presented to demonstrate their relative vehicle body stiffness.