• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1179-1181
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• 2001

For high performance induction motor drives such as mill drives, elevator, spindle drive, NC and so on, smart speed controls is usually required, that requires a precise current control. This paper is proposes design of fuzzy controller which makes use of the output voltage of the space vector PWM inverter. Also, proposes the performance fuzzy controller for high performance vector control of induction motor drive system. The performance of a fuzzy controller is compared with that of an PI controller in an internal loop. The validity of the proposed technique is confirmed by simulation results for induction motor drive system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.354-358
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• 2007

An experimental study was performed to understand spray characteristics of the slinger injector. system for the micro turbojet engine. In this fuel injection system, fuel is sprayed and atomized in the combustor by centrifugal forces of engine shaft. This experimental apparatus consist of a high speed rotating Spindle, slinger injector, pressure tank and acrylic case. The droplet size and velocity were measured by PDPA(Phase Doppler Particle Analyzer) and spray was visualized by using Nd-Yag laser-based flash photography. From the test results, the droplet size(SMD) is largely affected to rotational speed, mass flow rate and the number of injection orifice. From the this experimental study, we could understand the spray characteristics of the slinger injection system and obtain the optimum shape of the slinger injector nozzle which is suitable for the micro turbojet engine.

• Composites Research
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• v.14 no.3
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• pp.77-89
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• 2001

Since the critical whirling vibration frequency of high speed built-in type motor spindle systems is dependent on the rotor mass of the built-in motor and the spindle specific bending modulus, the rotor and the shaft were designed using magnetic powder containing epoxy and high modulus carbon fiber epoxy composite, respectively. In order to increase the amount of the magnetic flux of the composite squirrel cage rotor of an AC induction motor, a steel core was inserted into the composite rotor. From the magnetic analysis, the optimal configurations of steel core and conductor bars for the dynamic characteristics of the rotor system were determined and proposed. The temperature dependence of composite squirrel cage rotor materials was investigated by various experiments such as TMA, DMA and VSM.

• Advances in materials Research
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• v.2 no.4
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• pp.181-193
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• 2013

Description and theory of spin coating technique has been elaborately outlined and a spin coating machine designed and fabricated using affordable components. The system was easily built with interdisciplinary knowledge of mechanics, fluid mechanics and electronics. This equipment employs majorly three basic components and two circuit units in its operation. These include a high speed dc motor, a proximity sensor mounted at a distance of about 15 mm from a reflective metal attached to the spindle of the motor to detect every passage of the reflective metal at its front and generate pulses. The pulses are transmitted to a micro-controller which process them into rotational speed (revolution per minute) and displays it on a lead crystal display (LCD) which is also a component of the micro-controller. The circuit units are a dc power supply unit and a PWM motor speed controlling unit. The various components and circuit units of this equipment are housed in a metal casing made of an 18 gauge black metal sheet designed with a total area of 1, $529.2cm^2$. To illustrate the use of the spin-coating system, ZnO sol-gel films were prepared and characterized using SEM, XRD, UV-vis, FT-IR and RBS and the result agrees well with that obtained from standard equipment and a speed of up to 9000 RPM has been achieved.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1401-1417
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• 2004

Experimental and computational studies were performed to determine the effects of different blade designs on a flow pattern inside a double-spindle counter rotating mower deck. In the experimental study, two different blade models were tested by measuring air velocities using a forward-scatter LDV system. The velocity measurements were taken at several different azimuth and axial sections inside the deck. The measured velocity distributions clarified the air flow pattern caused by the rotating blades and demonstrated the effects of deck and blade designs. A high-speed video camera and a sound level meter were used for flow visualization and noise level measurement. In the computational works, two-dimensional blade shapes at several arbitrary radial sections have been selected for flow computations around the blade model. For three-dimensional computation applied a non-inertia coordinate system, a flow field around the entire three-dimensional blade shape is used to evaluate flow patterns in order to take radial flow interactions into account. The computational results were compared with the experimental results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.53-57
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• 2007

고속회전의 원심력으로 연료를 공급하고 액체연료의 미립화를 초래하는 회전연료분무장치에 대한 분무특성 시험연구를 수행하였다. 특정한 공간상에 존재하는 액적의 특성을 이해하고자 고속회전 연료분사시스템을 설계 제작하였다. 시험장치는 고속으로 회전하는 Spindle, 회전연료노즐, 가압식 물탱크, 아크릴 케이스로 구성하였다. 액적의 크기와 속도를 측정하기 위해 PDPA(Phase Doppler Particle Analyzer)시스템을 사용하였고, ND-Yag Laser를 사용하여 분무를 가시화 하였다. 시험결과 고속회전 연료분사시스템의 분무특성을 확인할 수 있었고, 회전속도는 액적 크기, 속도, 분무각 및 분무패턴 등의 분무특성에 주요한 영향을 미치는 것으로 확인되었다.

• Journal of the Semiconductor & Display Technology
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• v.6 no.4
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• pp.23-27
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• 2007

Rotary stages in semiconductor, display industry and many other fields require challenging accuracy to perform their functions properly. Especially, Axis of rotation error on rotary system is significant; such as the spindle error motion of the aligner, wire bonder and inspector machine which result in the poor quality products. To evaluate and improve the performance of such precision rotary stage, undesired movements on the other 5 degrees of freedom of the rotary stage must be measured and analyzed. In this paper, we have measured the three translations and two tilt motions of the worm gear type spindle with high precision capacitive sensors. To obtain the radial error motion, we have used Donaldson's reversal technique. And the axial components of the spindle tilt error motion can be obtained accurately from the axial direction outputs of sensors by Estler face motion reversal technique. Further more we have designed and developed the sensor mounting jig with standard cylinder for reversal method.

• Design & Manufacturing
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• v.17 no.2
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• pp.15-21
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• 2023

In this study, a diamond turning machine and a laser-assisted machining module were utilized for the complex combined cutting of aspheric shapes and fine patterns on the surface of high-hardness brittle material, silicon. The analysis of material's form accuracy and corrective machining was conducted based on key factors such as laser output, rotational speed, feed rate, and cutting depth to achieve form accuracy below 1 ㎛ and surface roughness below 0.1 ㎛. The cutting condition and corrective machining methods were investigated to achieve the desired form accuracy and surface roughness. The rotational speed of the spindle and the linear feed rate of the diamond turning machine were varied in five stages for the cutting condition test. Surface roughness and form accuracy were measured using both a contact surface profilometer and a non-contact surface profilometer. The experimental results revealed a tendency of improved surface roughness with increased rotational speed of the workpiece, and the best surface roughness and form accuracy were observed at a feed rate of 5 mm/min. Furthermore, based on the cutting condition experiments, corrective machining was performed. The experimental results demonstrated an improvement in form accuracy from 0.94 ㎛ to 0.31 ㎛ and a significant reduction in the average value of the surface roughness curve from 0.234 ㎛ to 0.061 ㎛. This research serves as a foundation for future studies focusing on the machinability in relation to laser output parameters.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1822-1827
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• 2003

End-milling have been used widely in industrial system because it is effective to a material manufacturing with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in precision machine part and electronic part. The optimum surface roughness has an effect on end-milling condition such as, cutting direction, spindle speed, feed rate and depth of cut, etc. Therefore this study was carried out to presume for mutual relation of end-milling condition to get the optimum surface roughness by regression analysis. The results shown that coefficient of determination($R^{2}m$) of regression equation has a fine reliability over 80% and regression equation of surface rough is made by regression analysis.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.46-52
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• 2003

End-milling have been used widely in industrial system because it is effective to a material manufacturing with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in precision machine part and electronic part. The optimum surface roughness has an effect on end-milling condition such as, cutting direction spindle speed, feed rate and depth of cut, etc. Therefore this study was carried out to presume for mutual relation of end-milling condition to get the optimum surface roughness by regression analysis. The results shown that coefficient of determination($\textrm{R}^2$) of regression equation has a fine reliability of 87.5% and regression equation of surface rough is made by regression analysis.