• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.292-297
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• 1997

The rattle noise is the most significant in many kinds of manual gearbox noises, which is generated at the idle stage of the engine operation. The main torsional vibration source of the driveline is the fluctuation of the engine torque. The gear rattle is impacts generating in the backlash of the free gear due to this torsional vibration. Many researchers reported the clutch torsional characteristic optimization method to reduce the idle gear rattle but only few of them give sufficient consideration to the system parameters like gear backlash, drag torque, system inertia, inertia distribution, engine torque fluctuation, idle engine rotation speed, and accessory load. This paper pays attention to the gear impact mechanism and system design parameters to reduce the idle gear rattle with computer simulation.

• 한국공작기계학회논문집
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• 제16권2호
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• pp.63-69
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• 2007

The surface roughness in centerless grinding is mainly affected by the many process parameters. For improving the surface roughness, the control of grinding parameters is very important. This paper deals with the analysis of the process parameters such as height of renters, tilting angle of the regulating wheel with respect to grinding wheel, rotation speed of regulating wheel, which are developed based on design of experiments such as factorial design. The investigation can enhance the surface roughness of ferrule. Finally, we have verified improved results of the optimized conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1839-1844
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• 2003

In order to provide a tool for designing more efficient methods of mixing fabric, a simplified discrete element computational model was developed for modeling fabric dynamics in a rotating horizontal drum. Because modeling the interactions between actual pieces of fabric is quite complex, a simplified model was developed where individual pieces of bundled fabric are represented by spherical particles. The simulations are used to investigate fabric bundle kinematics, the power required to drive the rotating drum, and the power dissipated through normal and tangential contacts. Parametric studies indicate only fill percentage, drum rotation speed, and friction coefficient play significant roles in the fabric bundle dynamics.

• 한국공작기계학회논문집
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• 제11권5호
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• pp.58-64
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• 2002

Mirror surface finish of Si-wafers has been achieved by rotary in-feed machining with cup-type wheels in ELID grinding. But the diameter of the workpiece is limited with the diameter of the grinding wheel in the in-feed machining method. In this study, some finding experiments by the rotary surface grinding machine with straight type wheels were conducted, by which the possible grinding area of the workpiece is independent of the diameter of the wheels. For the purpose of investigating the grinding characteristics of large scale diametrical silicon wafer, grinding conditions such as rotation speed of grinding wheels and revolution of workpieces are varied, and grinding machine used in this experiment is rotary type surface grinding m/c equipment with an ELID unit. The surface ground using the SD8000 wheels showed that mirror like surface roughness can be attained near 2~6 nm in Ra.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.405-409
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• 2003

We explored a new rough grinding technique on optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and range of diamond resin bond wheel. The grinding parameters such as workpiece rotation speed depth of cut and feed rate were altered while grinding the workpiece surfaces of 20m in diameter. Surface roughness is measured by Form Talysurf series2. Our target is to define grinding conditions producing the surface roughness better than 0.02${\mu}{\textrm}{m}$ Ra and the form accuracy of around 0.2${\mu}{\textrm}{m}$ PV.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.345-347
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• 2007

The microstructures and mechanical properties with the different Sc content of AA2519 FSW joint were investigated in this study. The sound FSW joints were obtained under applied all welding conditions such as the Sc content and the tool rotation speed. The grain size of the stir zone decreased slightly with increasing the Sc content. And the ultimate tensile strength increased and elongation decreased with increasing the Sc content. The intermetallic compound contained the Sc is considered to bring out the improvement of mechanical property in FSW joint.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.226-228
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• 2005

Of typical welding techniques, to employ the heat for joining process is the most commonly used welding process. But there arise difficulties when this process is applied to light weight alloys such as Aluminium alloy. In this respect, Friction Stir Welding(FSW), a solid-state joining process, is the most effective welding technique with significant potential for various industrial applications. In this study, the characteristics of lapping FSW Al 5052 alloy are shown under a variety of welding parameters such as the rotation speed of FSW tool and welding velocity. Conclusively, the welding properties of lapping FSW Al 5052 were found to be dominated by the deformation of non-joining area near the welding nugget rather than other factors such as the thermal input.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.559-564
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• 2009

Aluminum extrude is increasing to vehicle body manufacture of a recent railroad vehicle. Conventional welding of this aluminum extrude has been used MIG welding or resistance spot welding mainly. But the advanced manufactures like Japan's tried to apply the friction stir welding and friction spot joining at railroad vehicle body manufacture process. Therefore in this paper we tried to study to apply friction stir welding to AL 6005-T6 extrude which has been manufactured the railroad vehicle mainly. In this study we investigated first the mechanisms to affect the welding strength in friction stir welding. After we made the 3 tools of different shape, we observed how the welding strength changed while changing the welding time and the rotation speed, the plunging depth.

• 한국공작기계학회논문집
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• 제14권2호
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• pp.83-90
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• 2005

A mirror cam mechanism a kind of conjugate cam mechanism consists of two cams, two rollers, and two links. Since profiles of two mirror cam are identical, a simultaneous machining of two cams is achievable. Some machining errors on cam profiles do not result in the internal acting force, which often causes problems in high speed cam mechanism between two links. Also, since angular accelerations of two links are same, the internal acting force by the difference of the angular accelerations does not occur in the mechanism. Thus the mirror cam mechanism is very useful in high speed machinery. This paper studies a design method as well as a machining method, and develops an exclusive CAD/CAM software for mirror cam profiles. The developed CAD/CAM software is applied to a typical mirror cam mechanism and a mock-up equipment is built in order to test the machinism mirror cm. Experimental investigations show that the contact between cam surface and roller surface according to cam rotation agrees well with the simulation on the developed CAD/CAM software.

• 한국재료학회지
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• 제22권3호
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• pp.123-129
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• 2012

The microstructures and mechanical properties of friction stir welded lap joints of Inconel 600 and SS 400 were evaluated; friction stir welding was carried out at a tool rotation speed of 200 rpm and welding speed of 100 mm/min. Electron back-scattering diffraction and transmission electron microscopy were introduced to analyze the grain boundary characteristics and the precipitates, respectively. Application of friction stir welding was notably effective at reducing the grain size of the stir zone. As a result, the reduced average grain size of Inconel 600 ranged from $20{\mu}m$ in the base material to $8.5{\mu}m$ in the stir zone. The joint interface between Inconel 600 and SS 400 showed a sound weld without voids and cracks, and MC carbides with a size of around 50 nm were partially formed at the Inconel 600 area of lap joint interface. However, the intermetallic compounds that lead to mechanical property degradation of the welds were not formed at the joint interface. Also, a hook, along the Inconel 600 alloy from SS 400, was formed at the advancing side, which directly brought about an increase in the peel strength. In this study, we systematically discussed the evolution of microstructures and mechanical properties of the friction stir lap joint between Inconel 600 and SS 400.