• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.2
• /
• pp.105-111
• /
• 2012

High speed machining is the core technology that influences the performance of machine tools, and the high speed motor spindle is widely used for the high speed machine tools. The important problem in high speed spindle is to minimize the thermal effect by motor and bearing and frequency effect. This paper presents the thermal characteristic analysis and frequency experiment for a high speed spindle considering the flow rate of cooling oil. A high speed spindle is composed of angular contact ceramic ball bearings, high speed built-in motor, oil cooling jacket and so on. The thermal analyses of high speed spindle need to minimize the thermal effect and maximize the cooling effect and they are carried out under the various cooling conditions. Heat generations of the bearing and the high speed motor are estimated from the theoretical and experimental data. To find out the characteristic of vibration, the high speed spindle is excited in operational range. This result can be applied to the design and manufacture of a high speed tapping spindle.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.04a
• /
• pp.281-286
• /
• 2004

The vacuum cleaner motor runs on very high speed for the suction power. Specially, the motive power is provided by the impeller being rotate on very high speed. And centrifugal fan consists of the impeller, the diffuser, and the circular casing. Due to the high rotating speed or the impeller and small gap distance between the impeller and diffuser, the centrifugal fan makes very high noise level at BPF and harmonic frequencies. In order to calculate the sound pressure of centrifugal fan, the unsteady flow data is needed. And Noise cause is dividing to fluid noise by exhaust flow of fan and vibration noise by rotational vibration of vacuum cleaner fan motor. Until now, measuring method has been used to measure vibration by the accelerometer; this method has been not measured for the vibration in some parts of brush and commutator because of motor construction and 3-D vibrating mode. This paper was purposed on the accurate analysis, using laser vibration analyzer,. By using this measured data of noise cause against the difficult part in old times, we would like to use for the design of silent fan motor.

• 정보저장시스템학회:학술대회논문집
• /
• 2005.10a
• /
• pp.197-202
• /
• 2005

Current Optical Disk drive is dominating high share gradually in information storage device market through development of great skill. These technologies can achieve not only improvement of transmission speed but also elevation of recording/reproduction technology. However, these present state cause not only the increase of vibration in structural viewpoint but also problem of serious noise while the ODD becomes high speed/high performance. Specially, air-born noise is being bigger than structural-born noise as disk rotation speed increases gradually. The object of this research is that reduce the air-born noise in optical disk drive by reducing a quantity of flow by using a miniaturized muffler. The micro muffler is a miniaturized muffler. The muffler is used widely by solution to reduce air-born noise which is generated by flow. According to frequency band of the noise source, it can be applied by muffler of various forms. In this research, we examined the noise characteristics of the micro muffler and applied it by noise reduction solution of the ODD. It could get an excellent noise reduction in high frequency band by using the micro muffler than the opened case through the decrease of an inner flow. But it could not get a noise reduction in low frequency band through the decrease of an inner flow.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.9 no.2
• /
• pp.96-101
• /
• 2000

In machining with cutting tool inserts having complex chip groove shape the flow curl and breaking pattern of the chip are different than in flat-face inserts. In the present work an effort is made to understand the three basic phe-nomena occurring in a chip since its formation in machining with groove type and pattern type inserts. These are the ini-tial chip flow the subsequent development of up and side curl and the final chip breaking due to the development of tor-sional and bending stresses. in this paper chip flow angle in a groove type and pattern type inserts. The expres-sion for chip flow angle in groove type and pattern type inserts is also verified experimentally using high speed filming techniques.

• Journal of Mechanical Science and Technology
• /
• v.18 no.12
• /
• pp.2190-2203
• /
• 2004

A combined procedure for two-dimensional Delaunay mesh generation algorithm and an adaptive remeshing technique with higher-order compressible flow solver is presented. A pseudo-code procedure is described for the adaptive remeshing technique. The flux-difference splitting scheme with a modified multidimensional dissipation for high-speed compressible flow analysis on unstructured meshes is proposed. The scheme eliminates nonphysical flow solutions such as the spurious bump of the carbuncle phenomenon observed from the bow shock of the flow over a blunt body and the oscillation in the odd-even grid perturbation in a straight duct for the Quirk's odd-even decoupling test. The proposed scheme is further extended to achieve higher-order spatial and temporal solution accuracy. The performance of the combined procedure is evaluated on unstructured triangular meshes by solving several steady-state and transient high-speed compressible flow problems.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1999.10a
• /
• pp.381-386
• /
• 1999

In machining with cutting tool inserts having complex chip groove shape, the flow, curl and breaking patterns of the chip are different than in flat-face type inserts. In the present work, an effort is made to understand the three basic phenomena occurring in a chip since its formation in machining with groove type and pattern type inserts. These are the initial chip flow, the subsequent development of up and side curl and the final chip breaking due to the development of torsional and banding stresses. In this paper, chip flow angle in a groove type and pattern type inserts. The expression for chip flow angle in groove type and pattern type insets is also verified experimentally using high speed filming techniques.

• 한국가시화정보학회:학술대회논문집
• /
• 2004.12a
• /
• pp.41-45
• /
• 2004

The dynamic particle image velocimetry (PIV) is consisted of a high frequency pulse laser, high speed cameras and a timing controller. The three velocity components of flow downstream of an axial flow fan for PC cooling system are measured using the dynamic PIV system. An Axial flow fan has seven blades of 72 mm in diameter. The rotating speed is 1800 rpm. The downstream flow is visualized by smoke particles of about $0.3-1\;{\mu}m$ in diameter. The three-dimensional instantaneous velocity fields are measured at three downstream planes. The swirl velocity component was diffused downstream and the change in time-mean vorticity distribution downstream was also discussed. The spatio-temporal change in axial velocity component with the blades passing is recognized by the instantaneous vector maps. And the dynamic behavior of vorticity moving with the rotating blades is discussed using the unsteady vorticity maps.

• Journal of Korean Port Research
• /
• v.14 no.1
• /
• pp.66-75
• /
• 2000

From the traffic analysis, and model constructions and verifications for speed prediction on the freeway ramp junctions with 70mph speed limit, the following results were obtained : ⅰ) The traffic flow distribution showed a big difference depending on the time periods. Especially, more traffic flows were concentrated on the freeway junctions in the morning peak period when compared with the afternoon peak period. ⅱ) The occupancy distribution was also shown to be varied by a big difference depending on the time periods. Especially, the occupancy in the morning peak period showed over 100% increase when compared with the 24hours average occupancy, and the occupancy in the afternoon peak period over 25% increase when compared with the same occupancy. ⅲ) The speed distribution was not shown to have a big difference depending on the time periods. Especially, the speed in the morning peak period showed 10mph decrease when compared with the 24hours'average speed, but the speed did not show a big difference in the afternoon peak period. ⅳ) The analyses of variance showed a high explanatory power between the speed predictive models(SPM) constructed and the variables used, especially the upstream speed. ⅴ) The analysis of correlation for verifying the speed predictive models(SPM) constructed on the ramp junctions were shown to have a high correlation between observed data and predicted data. Especially, the correlation coefficients showed over 0.95 excluding the unstable condition on the diverge section. ⅵ) Speed predictive models constructed were shown to have the better results than the HCM models, even if the speed limits on the freeway were different between the HCM models and speed predictive models constructed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1999.10a
• /
• pp.111-121
• /
• 1999

From the traffic analyses, and model constructions and verifications for speed prediction on the freeway ramp junctions with 70mph speed limit, the following results obtained: ⅰ) The traffic flow distribution showed a big difference depending on the time periods. Especially, more traffic flows were concentrated on the freeway junctions in the morning peak period when compared with the afternoon peak period. ⅱ) The occupancy distribution was also shown to be varied by a big difference depending on the time periods. Especially, the occupancy in the morning peak period showed over 100% increase when compared with the 24hours average occupancy, and the occupancy in the afternoon peak period over 25% increase when compared with the same occupancy.ⅲ) The speed distribution was not shown to have a big difference depending on the time periods. Especially, the speed in the morning peak period shown 10mph decrease when compared with the 24hours' average speed, but the speed did not show a big difference in the afternoon peak period.ⅳ) The analyses of variance showed a high explanatory power between the speed predictive models(SPM) constructed and the variables used, especially the upstream speed. ⅴ) The analysis of correlation for verifying the speed predictive models(SPM) constructed on the ramp junctions were shown to have a high correlation between observed data and predicted data. Especially, the correlation coefficients showed over 0.95 excluding the unstable condition on the diverge sectionⅵ) Speed predictive models constructed were shown to have the better results than the HCM models, even if the speed limits on the freeway were different between the HCM models and speed predictive models constructed.

• Journal of computational fluids engineering
• /
• v.19 no.3
• /
• pp.91-97
• /
• 2014

A high resolution numerical method aimed at solving cavitating flow was proposed and applied to gas-liquid two-phase shock tube problem with arbitrary void fraction. The present method with compressibility effects employs a finite-difference 4th-order Runge-Kutta method and Roe's flux difference splitting approximation with the MUSCL TVD scheme. The Jacobian matrix from the inviscid flux of constitute equation is diagonalized analytically and the speed of sound for the two-phase media is derived by eigenvalues. So that the present method is appropriate for the extension of high order upwind schemes based on the characteristic theory. By this method, a Riemann problem for Euler equations of one dimensional shock tube was computed. Numerical results of high speed flow phenomena such as detailed observations of shock and expansion wave propagations through the gas-liquid two-phase media and some data related to computational efficiency are made. Comparisons of predicted results and solutions at isothermal condition are provided and discussed.