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: Exhaust system by reinforcement of environment regulation came to the foe study necessity. And Exhaust system has necessary to increase the engine performance and silence. From this cause, Automobile has significantly considered production expense. this study makes process for checking the characteristics about Exhaust variable valve within muffler. Variable valve might reduce the baffle within muffler, It was possible to remove the front muffler. Therefor, To miniaturize a size of muffler might be increased by performance through cost-cutting effect and controling of back pressure. Because the Study on Variable valve installed within muffler, to measure the real data was hardly resulted one of the assignments. From manufactured conduct device, might measure data one of piece which was up-graded of problem. Considering to these point, stressed pressure distribution has analyzed on cross section, floating characteristics about velocity distribution around variable valve using analysis as computational fluid dynamics of Ansys with completed measurement data.

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: This research was conducted structural analysis in order to analyze the impact of the gear in Urea pump when the water is frozen. Subject of study, gear was designed nine models, this gear is a spur gear, located in pump. Contact conditions and rotation conditions were set the gear's condition of restriction. Given 136 MPa pressure to external gear by water was set to the applied stress. The performing result of structural analysis, maximum stress and strain are appeared between two gears. At the same diameter, strain and stress are decreased gradually thicker. Because of the little part in crevice between gears, this parts of gears could be obtained conclusion to be generated maximum stress and strain.

: Since resources of fossil fuels are limited, development of alternative energies is emphasized and research on new-regenerative energy is actively in progress worldwide. In present research, physical and chemical characteristics of mixed fuel are analyzed in detail for the different mixture rate of conventional and bio-diesel and ultrasonic irradiation time. Experimental setup consists of ultrasonic generator, vibrator, horn, and reflector. Various physical and chemical characteristics of fuel are investigated for volumetric mixture rate of bio-diesel from 0 to 100%. As results, viscosity and surface tension is increased as mixture rate of bio-diesel is increased. Also, molecular splits and reunions are increased and decreased repeatedly after some period of time as ultrasonic energy irradiation time is increased. As conclusion of experiments, Olefin rate, Branch index, and Aromatic rate are influenced by ultrasonic irradiation time.