• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.181-183
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• 2000

Ultrasonic Motors of Wind-Mill type(diameter in 11.35mm, thickness in 2.8mm, and 1.44g weight) using Piezoelectric Ceramics have been developed. In recent study, Maximum torque in 100$V_{max}$, 105.8kHz was 7.2 ${\mu}$N$.$m, and bidirectional revolution using single-phase AC was presented. However, it is difficult to use because of small torque. Thus, in present study, new type of Wind -Mill Type Ultrasonic Motor of was designed as stator' structure was changed

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1720-1722
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• 1999

In this paper, we studied the properties of small-size disk-type ultrasonic motor using travelling wave for the application to the precise control robotic joint motor and fabricated it. The diameter of the ultrasonic motor fabricated was 13mm. Also, the piezoelectric vibrator was constructed by piezoelectric ceramic and elastic material. The piezoelectric ceramic was composed to PZ-PT-PMN which was shown the high electromechanical stability under high vibration level and stainless steel was used as the elastic material in which configuration was disk-type. To conform the capability of application to robotic motor, we measured the change of rotational speed according to applied voltage and applied frequency. As the results, the small-size disk-type ultrasonic motor was able to fabricate, and the revolution speed was 350 [rpm] when input voltage was 55 [Vrms] and applied frequency 160.4 [kHz] under pre-load.

• Journal of Mechanical Science and Technology
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• 제19권spc1호
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• pp.336-342
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• 2005

The DC motor of a vehicle may cause noise and vibration due to high-speed revolution, which can make a driver feel uncomfortable. There have been various studies attempting to solve these problems, mostly focusing on the causes of noise and vibration and a means of preventing them. The CAE methodology is more efficient than a real test for the purpose of looking for various design parameters to reduce the noise and vibration of the DC motor. In this study, a design process for reducing brush noise is presented with the use of a computer model, which is made by using a multi-body dynamics program (DADS). The design parameters to reduce the brush noise and vibration were proposed using a computer model. They were used to reduce the noise and vibration of the DC motor and verified by the test results of the fan DC motor in the vehicle. This method may be applicable to various DC motors.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.875-880
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• 2004

The DC Motor of a vehicle may cause noise and vibration due to high-speed revolution, which can make a driver feel uncomfortable. There have been various studies that attempted to solve these problems, mostly focusing on the causes of noise and vibration and the means of preventing them. The CAE methodology is more efficient than a real test for the purpose of looking for various design parameters to reduce the noise and vibration of the DC motor. In this study, a design process for reducing brush noise is presented with the use of a computer model, which is made by using a multi-body dynamics program (DADS). The design parameters to reduce the brush noise and vibration were proposed using a computer model. They were used to reduce the noise and vibration of a DC motor and verified by the test results of a fan DC motor in a vehicle. This method may be applicable to various DC motors.

• 한국전자통신학회논문지
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• 제5권2호
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• pp.164-170
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• 2010

브러시리스(brushless) DC 전동기는 회전자의 위치에 따라 3상 중 2상에 전류를 흐르게 하는 방식으로 구동되며 회전자의 위치를 검출하기 위해서는 홀센서나 엔코더등과 같은 자기식 또는 광학식 위치 검출 센서가 사용되는데 이러한 센서들은 고온이나 저온에서 원치 않는 동작을 유발할 수 있고 전동기의 가격과 부피를 증가시키는 단점이 있다. 최근에는 전동기의 가격과 부피적 측면 그리고 강건성을 고려하여 센서리스(Sensorless) 전동기 구동에 관한 연구가 활발히 이루어지고 있다. 본 논문은 전동기를 Unipolar PWM 방법으로 고속으로 회전시킬 경우 발생되는 노이즈에 의해 Zero Crossing Point 관측이 어려워 정확한 제어가 용이하지 않은 문제점을 개선하여 드라이버의 수명을 증대시키면서 고속에서도 노이즈를 최소화 할 수 있는 새로운 스위칭 방법을 제안한다.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.158-165
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• 2004

The DC motor in a vehicle may cause noise and vibration because of high speed revolution, which can make a driver feel uncomfortable. There have been various studies attempting to solve these problems, focusing mostly on the causes of and ways to reduce noise and vibration. It is suggested that the noise in a DC motor may be primarily due to interaction between a brush and a commutator. Brush noise, the most common noise in a DC motor, results from a brush bounced from the surface of the commutator, fluctuation of the friction between the brush and the commutator, and the impact on the brush when passing over slots of the commutator. Based on the noise test, one of the most important design parameters was shown to be the roundness of the commutator. As the DC motor is used, the roundness of the commutator gets bigger with subsequent increase of the level of brush noise and vibration. There must be a threshold in order to prevent the brush noise from getting worse. Using the method of CAE is more efficient than the real test for purposes of looking for various design parameters to maintain the roundness of the commutator. In this study, the design process to reduce the brush noise is presented with the use of a computer model. The design parameters to reduce the brush noise and vibration are proposed by using FEM. The design parameters are used to reduce the noise and vibration of a DC motor and it is verified with the test results on a fan DC motor in a vehicle. This method may be applicable to various DC motor.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.764-769
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• 2004

The DC Motor in a vehicle may cause noise and vibration because of high speed revolution, which can make a driver feel uncomfortable. There have been various studies attempting to solve these problems, focusing mostly on the causes of and ways to reduce noise and vibration. It is suggested that the noise in a DC Motor may be primarily due to interaction between a brush and a commutator. Brush noise, the most common noise in a DC Motor, results from a brush bounced from the surface of the commutator, fluctuation of the friction between the brush and the commutator, and the impact on the brush when passing over slots of the commutator. Based on the noise test, one of the most important design parameters was shown to be the roundness of the commutator. As the DC motor is used, the roundness of the commutator gets bigger with subsequent increase of the level of brush noise and vibration. There must be a threshold in order to prevent the brush noise from getting worse. Using the method of CAE is more efficient than the real test for purposes of looking for various design parameters to maintain the roundness of the commutator. In this study, the design process to reduce the brush noise is presented with the use of a computer model. The design parameters to reduce the brush noise and vibration are proposed by using FEM. The design parameters are used to reduce the noise and vibration of a DC motor and it is verified with the test results on a fan DC motor in a vehicle. This method may be applicable to various DC motors.

• 유공압시스템학회논문집
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• 제7권3호
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• pp.7-12
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• 2010

In the case of hydraulic piston motor, hydrostatic bearing is designed to be adapted the hydrostatic bearing for the relative lubrication in the structural design. It's available to make it highly efficient and that's why it's widely used. The thing which largely influence the high pressure, the high efficiency, and the life is the hydrostatic bearing between a shoe and a swash plate. In this study, with the most general "hydrostatic bearing shoe" that has one recess as the subject of this research, I designed and made the 4 kind of piston shoe that have different orifice diameter each other, and studied the features of the hydrostatic bearing by observing the change of the leakage flow rate, the torque and the volumetric efficiency through experiments on the changes of the pressure & the speed of the revolution. As a result, the bigger diameter of the orifice, the less torque. And with an increase of the orifice diameter under the high pressure, the leakage flow rate decreased remarkably. Also it was observed the leakage flow rate increased linearly according to the increase of the supply pressure.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.742-747
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• 1998

In the High-Speed range for salient type synchronous reluctance motors, the effect of iron loss can not be negligible. In this paper, the SynRM without cage is analyzed mathematically to model and the speed control system is examined by simulation. In order to control the revolution speed, a closed-loop control with vector control and decoupling control are applied to the high-speed SynRM drives. The speed control system is analyzed to investigate the desired speed characteristics of high SynRM by simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.282-284
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• 1997

Ultrasonic motors using piezoelectric ceramics and brass metal endcaps were fabricated, which is operated by single - phase high frequency. The structure of the ultrasonic motors has the wind-mill type. The stator part consists of a piezoelectric disk and two metal endcaps slotted wind-mill type. According to the piezoceramic disk vibrates as a radial mode, two metal endcaps provide both longitudinal and torsional displacements simultaneously. Because the metal endcaps have a nonsymmetric structure. the principle of the ultrasonic motor is not well understood. The dimension of the ultrasonic motor is diameter in 12.7 mm and thickness in 2.0 mm, and especially the PMN-PT-PZ piezoelectric disk was used. The maximum revolution speed 700 rpm and the maximum torque 0.22 mN.m were obtained. The ultrasonic motor for rotation was Supplied only single phase AC.