• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.353-360
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• 2015

Commercial drivers feel tired more than the general public, because their driving times are long and they experience more idle vibration. In this study, we developed a nonlinear model of a magnetic, linear spring seat suspension to determine the optimal design to improve ride comfort. The resonant frequency for the optimal design of the suspension was found to be 3.5 Hz, and the stiffness was analyzed through displacement-load experiments. Additionally, the vibration transmissibility was analyzed by the suspension stiffness, and the existing coil spring type vibration transmissibility was found to be 0.99. A parallelogram type magnetic spring was determined to result in a better performance than the existing spring with a vibration transmissibility of 0.823.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1051-1054
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• 2003

For micro-weighing, null balance method is widely used in the precision industrial fields, such as biomedicine, semiconductor, chemistry and so on. In order to obtain high resolution and large measurement range simultaneously, the mechanism should be analyzed and optimized. However, large measurement error can be generated according to the mass loading position and this error is called as a corner loading error. The corner loading error is caused by the parallelism error of a Roberval mechanism used to minimize it. The corner loading error is one of the most dominant error sources that should be removed. It is possible to design that the mechanism has no corner loading error theoretically, but the mechanism of the micro weighing device is very difficult to be realized as original design due to assembling and manufacturing error. For the required specification of the device, the precise manufacturing technique under a few $\mu\textrm{m}$ is required for the realization of the design. In this paper, the effects of the parallelism error are analyzed by using Lagrange method and verified by experiment. Also, the compensation mechanism is proposed and the corner loading error is reduced by restoring tile parallelism.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.1
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• pp.183-193
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• 2003

Micro-weighing device by using null balance method is being essential part in fields of high-technology industries such as precision semiconductor industry, precision chemistry, biotechnology and genetics etc. Also, requirements for high resolution and for large measurement range increase more and more. The performance of the micro-weighing device can be determined by the mechanism design and analysis. The analytical design method has been proposed for the performance improvement such as resolution, measurement range and fast response. The 2-stage displacement amplification is designed to overcome the limit of conventional force transmitting lever. The parallel spring is designed for the measurement result independent of the input force position variation. Also, the natural frequency of mechanism is analyzed for the fast response. After each analysis, optimal design has been carried out. To verify the analysis and design result, characteristics experiments had been carried out after construction. Finally, the system had been controlled.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.921-926
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• 2015

Embossed aluminum sheets were been used in heat insulation purpose for automative exhaust parts because of increasing their surface areas and stiffness reinforcement. However, there are many restrictions because of high rate of wrinkle occurrence on press working. We have performed the tensile and bending tests for embossed sheets to clarity its mechanical properties and springback characteristics. Embossed aluminum sheets showed a different flow stress after plastic yielding due to flattening the embossed cone shape. Above all, yield stress of parallel embossed specimen decreases while its diagonal one increases and the decrease of young's modulus in the embossed sheets contributes to the increase of springback amount.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.31-39
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• 1996

In this paper, the error and its sources in manufacturing of bourdon tube pressure gage was studied, and the method to reduce such errors was discussed. In more detail, the effects of parallelism of rollers, spring back, uniformity of radius curvature and the ratio of circumferential speeds of rollers were invesrti- gated. As a reselt, we could find out that the aprallelism of roller affected to the displacement error at the free end of gage and that the amount of spring back was closely related with the ratio of circumferential speeds of rollers. The uniformity of curvature radius was determined by the distance between bending rollers and it was comparatively uniform in the range above 30 .deg. C from the both sides of tube. Also, the ratio of circumfer-ential speeds of rollers was finded out as a very important factor giving severe influence on the creep or the hysteresis of bourdon tube.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.755-761
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• 2014

Internal or external restraint of concrete strain due to drying shrinkage and creep in concrete structures causes mechanical strain and becomes a source of persistent change in creep-causing stress conditions. Mathematical modeling to incorporate the persistent change of creep-inducing stress is generally achieved with consideration of the ages of concrete and concrete properties at the times of loadings, and stress history. This paper presents an incremental format of creep model based on parallel creep concept to depict the creep under time-varying stress history in developing creep strain. Laboratory experiments are carried out to validate the performance of the presented creep model. Typical creep phenomena are addressed through the comparisons between the measured and predicted creep strains.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.73-79
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• 2012

Kiosks are widely used in drive-thru systems in parking lots or on the highway to provide various services to drivers. However, the driver must stop at an exact location to access the kiosk, since its panel is fixed. In order to improve the kiosk accessibility, in this study we developed a manipulator that can adjust the position of the kiosk panel. The number of active joints was minimized to lower the cost, whereas a parallelogram mechanism and passive joints were adopted to increase its convenience for the users. Furthermore, a safety mechanism using springs and a cam was designed to ensure the safety of the user in the case of an emergency. The performance of the position controller and the safety mechanism were verified through various tests. In addition, the proposed collision reaction strategy improved the safety performance of the kiosk system.