• Journal of Korean Society of Steel Construction
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• v.18 no.6
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• pp.783-792
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• 2006

This study investigates developments in a prestressing method using the thermal-expanded cover-plates that increases the load-carrying capacity of structures by installing it on upper or lower flanges in case that huge flexural stiffness according to the increase in span length or load are required of steel structure, such as rolled H-beam or built-up beam. This method applies multi-stepwise contraction forces generated by the contraction of cover plates as prestressing forces after joining the cover plate applied by multi-stepwise thermal expansion that was applied to induce prestressing to structures. To perform a theoretical investigation of the prestressing force applied to a structure due to the thermal expansion and induce a multi-stepwise prestressing method using multi-stepwise thermal distribution, this study proposes a theoretical heat transfer solution for the multi-stepwise thermal distribution of cover plates and analyzes the effect of a multi-stepwise prestressing method using the multi-stepwise thermal expansion.

• International Commerce and Information Review
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• v.19 no.3
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• pp.83-105
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• 2017

I tried to analyze export relation of influence in Chinese H beam(common steel), Hot Rolled Steel(common steel), Plate(common steel) which could be influenced immediately by China's cancellation of the export rebate of value added tax in 2010 through the statistic methods such as cointegration, Granger causality, impulse response and variance decomposition. In the first period they mutually influenced each other in export to Korea but in the second period, this relation of influence was lessoned. Due to production expansion of Hot Rolled Steel(common steel), Plate(common steel) in Korea, the change of import trend, the market change of steel users' industries and China's expedient export of boron steel to Korea, mutual influence among these products was greatly declined. Ever since Hyundai Steel's production expansion involving blast furnace facilities, there is need for the industry to concentrate on developing new markets for its facilities' output in Korea. Therefore, Korea's steel industry desperately needs strength of de-jure standards such as unique quality standards and related certifications, efficient distribution management, as well as export promotion strategy through its global trading network to effectively address its structural supply-demand imbalances.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.321-322
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• 2006

In many manufacturing processes such as web formation, manufacturing of paper and nonwoven, fabric weaving, etc., planar sheets are transported and at the same time appropriate tension is imposed. The input material rolled up on beams is fed by unwinding the beam and the processed is then taken up on beams by winding it. While processed, the planar sheets are thrown under the processing load of impulse form, which causes irregular thickness of the processed sheet. To improve the quality of the product, a dynamic model is needed and the dynamic characteristics is to be analyzed by simulation. This study shows that density variation dynamics of the in-process-sheet in the machine direction can be described at each moment of disturbing impacts in forms of difference equations, while the impacts and tension, the time-dependency of the material properties were taken into account. Simulation showed the most serious variation of the density occurred in the process starting phase. The starting velocity curve with step form showed the least variation of the density. As the time order of the function of the starting velocity cure becomes higher, the density variation gets greater.

• International Journal of Automotive Technology
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• v.6 no.2
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• pp.149-159
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• 2005

A full nonlinear finite element P185/70Rl4 passenger car radial-ply tire model was developed and run on a 1.7-meter-diameter spinning test drum/cleat model at a constant speed of 50 km/h in order to investigate the tire transient response characteristics, i.e. the tire in-plane free vibration modes transmissibility. The virtual tire/drum finite element model was constructed and tested using the nonlinear finite element analysis software, PAM-SHOCK, a nonlinear finite element analysis code. The tire model was constructed in extreme detail with three-dimensional solid, layered membrane, and beam finite elements, incorporating over 18,000 nodes and 24 different types of materials. The reaction forces of the tire axle in vertical (Z axis) and longitudinal (X axis) directions were recorded when the tire rolled over a cleat on the drum, and then the FFT algorithm was applied to examine the transient response information in the frequency domain. The result showed that this PI 85/70Rl4 tire has clear peaks of 84 and 45 Hz transmissibility in the vertical and longitudinal directions. This result was validated against more than 10 previous studies by either theoretical or experimental approaches and showed excellent agreement. The tire's post-impact response was also investigated to verify the numerical convergence and computational stability of this FEA tire model and simulation strategy, the extraordinarily stable scenario was confirmed. The tire in-plane free vibration modes transmissibility was successfully detected. This approach was never before attempted in investigations of tire in-plane free vibration modes transmission phenomena; this work is believed to be the first of its kind.