• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.980-984
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• 2002

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design condidering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verified the test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirm approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective method in thermal-appropriate design.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.316-318
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• 2007

Friction Spot Joining(FSJ) has a strong potential for aluminum alloy joining in automobile industries. The present paper focuses on the attempt to optimize the FSJ process for lap joining of A5052-H32 and A6061-T6 aluminum alloys. For A5052 maximum tensile shear strength has been observed for a tool rotating speed of 800rpm and for A6061 at 1000 rpm. Study on fracture modes of the tensile tested specimens of both A5052-H32 and A6061-T6 revealed, for high tensile strength values, plug fracture mode and lower tensile values, shear fracture mode. Above 2000 rpm distortion of the base metal, beside the tool shoulder was larger and plug fracture mode has been observed.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.2023-2026
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• 2002

This paper explains the study of controller design applied to SRM(Switched Reluctance Motor) concept. This controller executes controller algorithms via ${\mu}$-processor to increase stability and precise measurement, and VHDL (Very high speed integrated circuit Hardware Description Language) is designed to generate SRM driving signal. During initial period, SRM controller was designed to control .respective target RPM (Revolution per minutes) and PR (Proportional Integral Differential) coming from the PC(Personal Computer) monitor program, and receiving clockwise and counter-clockwise rotation signal and target RPM coming from the front panel, and receiving the location of rotational element and RPM generating from the position censor during activation period.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.498-503
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• 2002

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design considering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verified the test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirmn approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective mettled in thermal-appropriate design.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.476-481
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• 2003

In this paper, the effect of circumferential inlet distortion on performance and stall has been experimentally investigated in a high-speed centrifugal compressor, comparing distorted cases with undistorted one. The performance of compressor was slightly deteriorated by defect of inlet static pressure which is caused by the circumferential inlet distortion. As stall was fully developed the inlet distortion did not affect the number of stall cell and the propagation velocity. It also did not affect stall inception at 40,000 and 50,000 rpm. However stall occurred at the lower flow rate for distorted flow at 60,000 rpm. For 50,000 rpm a unexpected phenomenon occurred : stall occurred first and then it disappeared.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5082-5088
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• 2015

In this paper, durability test of 1000cc level gasoline engine has been carried out. Durability test set total 300 hours and WOT condition. Engine torque, power, fuel consumption, blow-by gas flow rate, and oil pressure are measured to analyse performance variation by time. As a result, engine performance of high rpm range gradually reduced by time but for relatively low rpm range shows stable performance. Blow-by gas flow rate shows 0.4% of averaged induction air flow rate, which is excellent rate for 1000cc level gasoline engine. Engine torque and fuel consumption data show the break-in upto 100 hours and aging trend after that. After 300 hours, engine is disassembled and each part is checked for the damage or crack.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.111-117
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• 2016

The cutting performance of a developed small-angle spindle tool was investigated with Al6061 using a TiAlN coated high-speed steel end mill. Up-cut and down-cut processes in a milling machine were carried out at the range of 1000-4000 rpm for spindle speed and 50-300 mm/min for feed rate. As a result, the highest cutting force in the Fx direction was obtained from the up-cut process when the spindle speed was 1000 rpm and the feed rate was 100 mm/min. In the Fy direction, the highest cutting force appeared in the up-cut process at a feed rate of 250 mm/min at the same spindle speed. Conversely, the lowest cutting force came out in the up-cut process at a spindle speed of 4000 rpm and a feed rate of 50 mm/min. As for surface finish, the finest surface roughness was obtained as Ra 0.7642 um at a spindle speed of 4000 rpm and a feed rate of 50 mm/min. Consequently, given the cutting performance of the developed small-angle spindle tool, we conclude that its use in industrial practice is feasible.

• Tribology and Lubricants
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• v.21 no.1
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• pp.8-15
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• 2005

In this study a general Galerkin FE lubrication analysis method is utilized to analyze the complex lubrication performance of a spiral groove seal, which is being designed and developed for a high-speed flying object application operating at a high-speed of over 50,000 rpm. As at the equilibrium seal clearance the axial stiffness of the seal is predicted to have almost such a constant high value of $1.04\times10^8\;N/m$ regardless of a rotating speed, the seal is expected to maintain a stable thickness of lubrication film under a certain external excitation acting. Also, as even at an ultra high-speed of 80,000 rpm the axial damping of the seal is shown to have a rotatively high value of 5,775 N-s/m, the dynamic stability of the seal system at the axial degree of freedom is assured well enough.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.5
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• pp.427-436
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• 2002

This paper presents an implementation of high-dynamic performance of position sensorless motion control system of Reluctance Synchronous Motor(RSM) drives for an industrial servo system with direct torque control(DTC). The problems of high-dynamic performance and maximum efficiency RSM drives controlled by DTC are saturation of stator linkage flux and nonlinear inductance characteristics with various load currents. The accurate estimation of the stator flux and torque are obtained using stator flux observer of which a saturated inductance $L_d$ and $L_q$ can be compensated by adapting from measurable the modulus of the stator current and rotor position. To obtain fast torque response and maximum torque/current with varying load current, the reference command flux is ensured by imposing $I_{ds} = I_{qs}$. This control strategy is proposed to achieve fast response and optimal efficiency for RSM drive. In order to prove rightness of the suggested control algorithm, the actual experiment carried out at $\pm$20 and $\pm$1500 rpm. The developed digitally high-performance motion control system shown good response characteristic of control results and high performance features using 1.0kW RSM which has 2.57 Ld/Lq salient ratio.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.305-309
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• 1999

This paper presents an high efficiency energy conversion system for very high-speed flywheel energy storage system using high Tc superconducting bearings. Main configuration of power convertor is designed to replace of the conventional battery with EMB(Electro Mechanical Battery). PMSM(Permanent Magnet Synchronous Motor) using Halbach array is used as the energy conversion system of motor and generator. Some PWM methods for the high frequency inverter is described and the power factor effects to the torque characteristics and efficiency of the motor and generator is analyzed. As the results, it is verified that the inverter output current is well regulated to be in-phase or inverse-phase sinusoidal waveform to have the wide operational range from 2,500rpm to 42,000rpm. Proposed circuit is designed to obtain the very high speed, high efficiency and stable rotational characteristics, and to be applied to1.2r[kW]/65[Wh] system.