• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.9
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• pp.427-433
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• 2001

A linear ultrasonic motor was designed by a combination of the first longitudinal and fourth bending mode, and the motor consisted of a straight aluminum alloys bar bonded with a piezoelectric ceramic element as a driving element. That is,$L_1-B_4$ linear ultrasonic motor can be constructed by a multi-mode vibrator of longitudinal and bending modes. Linear ultrasonic motors are based on an elliptical motion on the surface elastic body, such as bar or plates. In general, the natural resonance frequency of the stator is used as a driving frequency of the motor which provides a large elliptical motion. The corresponding eigenmode of one resonance frequency can be excited twice at the same time with a Phase shift of 90 degrees in space and time. And the rotation can be reversed by changing the phase between the two signals from sin$\omega$t to cos$\omega$t. Moreover, the tangential force pushes the slider(rotor) and, therefore, determines the thrust and speed of the motor. The experimental results of fabrication motors, bimorph-tyPe motor showed more excellent than unimorph-type. The maximum speed of TBL-200, TBL-300, TBL-400, TBL -220, TBL-310 and TBL-420 motors were 0.12, 0.37, 0.39, 0.14, 0.55 and $0.60ms6{-1}$, respectively. And the efficiency were reported 1.15, 7.9, 6.6, 2.36, 10.1 and 16.5%, respectively. That time, output thrust of the motor was a strong(1~2N) and the weight of stator was a lightness(5~7g).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.93-96
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• 2004

An ultrasonic linear motor was composed of a slider and a stator vibrator including piezoelectric material and elastic material. The ultrasonic linear motors mainly consist of an ultrasonic vibrator which generates elliptical oscillations. L1-B4 ultrasonic linear motor use longitudinal and bending multi-vibration. In order to design stators which has high efficiency and driving characteristics, The finite element method was used to optimize dimension of ultrasonic vibrator and direction of vibratory displacement. stator vibrator of respectively width 3, 5, 7[mm] was fabricated and experimented. as results When width was 5[mm], the driving characteristics was good.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.728-731
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• 2003

This paper deals with a flat type ultrasonic motor, which uses a longitudinal-bending multi mode vibrator of rectangular form. A linear ultrasonic motor was designed by combination of the first longitudinal and eighth bending mode, and the motor consisted of a straight aluminum alloy bar bonded with piezoelectric ceramic elements as a driving element. The geometrical dimensions of the rectangular aluminum vibrator were determined by Euler-Bernoulli theory ANSYS was used to analyze the resonance frequency and the displacement of the stator vibrator. The resonance frequency of the motor provides the elliptical motion. and ANSYS was used to analyze elliptical motion and elliptical trajectory of stator vibrator when thickness of piezoelectric ceramics was varied respectively 0.763, 1.526, 2.289[mm] and width of stator vibrator was varied respectively 16, 12, 8, 4[mm]. When thickness of piezoelectric ceramics was decreased, the displacement of the stator vibrator was increased. And when width of stator vibrator was decreased, the displacement of the stator vibrator was increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.730-733
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• 2004

An ultrasonic linear motor was composed af a slider and a stator vibrator including piezoelectric material and elastic material. The ultrasonic linear motors mainly consist of an ultrasonic vibrator which generates elliptical oscillations. $L_1-B4$ ultrasonic linear motor use longitudinal and bending multi-vibration. In order to design stators which has high efficiency and diriving characteristics. The finite element method was used to optimize dimension of ultrasonic vibrator and direction of vibratory displacement. stator vibrator of respectively width 3, 5, 7[mm] was fabricated an experimented. as results When width was 5[mm], the driving characteristics was good

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.323-326
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• 1997

Conventional robots actuated by motors with the speed reducer such as harmonic drive had weakness in delivering loads, pressing, grinding, and cutting jobs. To overcome this, the developer a new type of robot actuated by the ball screw. The robot is an articulated shape, which is composed of four axes. The base axis is actuated similarly with conventional robot, but the others are actuated by four bars mechanism composed of the ball screw. We setup the dynamics model of the robot. The robot has parameter uncertainties and nonlinearlity due to the ball screw actuator. To coordinate the robot, we applied sliding-mode control.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.107-112
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• 2010

A gas turbine consists of an upstream compressor and a downstream turbine with a combustion chamber, and also the compressor and the turbine are generally coupled using a single shaft. Large scale gas turbine compressor is designed as multi-stage axial flow and the blade is fan-type which is thick and wide. Recently radial cracking happens occasionally at the compressor blade tip of large scale gas turbine. So, FEM was performed on the compressor blade and vibration modes and dynamic stresses were analyzed. According to the analysis, 9th natural frequency mode of the blade, which is 2 strip mode, is near the vane passing frequency by the vane located at the upstream of the blade.

• The Journal of the Korea Contents Association
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• v.12 no.6
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• pp.78-91
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• 2012

The Terrestrial DTV service compliant with ATSC has been advancing for years. In KBA(Korean Broadcasters Association), a multi-channel service was broadcasted on air during the period of the 2006 FIFA World Cup Germany with the various type of MMS(Multi Mode Service) using MPEG-2 encoding method. MMS Service can provides not only one HD channel but also serveral additional services within 6MHz bandwidth. Using digital video compression technology(MPEG-2), many various programs such as HDTV, SDTV, Audio and Data are able to be transmitted within the same bandwidth. From November 2009, KBS has been preparing an advanced MMS service, 'Korea-View' which has both methods of encoding, MPEG-2 and H.264 that is compliant ATSC mobile standard, A/153. Korea-View is a kind of multi-channel broadcast service to provide one HD and 3 SD programs with the bandwidth of 6MHz. Terrestrial multi-channel service is required to focuse on expanding viewer service. Such Terrestrial multi-channel services will contribute to transferring to digital broadcasting and to extending the viewers' welfare. Due to advances in digital technology, Pay-TV channels has increased to hundreds. Even though digital switchover is being proceeded, terrestrial broadcasters have been unable to deliver multi-channel services. In this paper, technical features and differences of MMS and Koreaview will be analyzed regarding terrestrial multi-channel broadcasting services, and the politic direction will be proposed in accordance with introduction of future service.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.5
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• pp.55-60
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• 2001

Most of the battery charger for electric powered forklift truck are controlled by the method of 3-phased constant current and constant voltage controls. However, these chargers have several disadvantages like a large charger capacity, and a short battery life time. To eliminate the weak points, a digital type battery charger based on multi-mode control adding a constant power control and several assistant controls in the conventional control is presented. The whole control system is performed by a low cost 8 bit one-chip micro-controller and completely digitize. So, we can get a high precision control and a good reliability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.193-193
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• 2008

Wearable and ubiquitous micro systems will be greatly growing and their related devices should be self-powered in order to avoid the replacement of finite power sources, for example, by scavenging energy from the environment. With ever reducing power requirements of both analog and digital circuits, power scavenging approaches are becoming increasingly realistic. One approach is to drive an electromechanical converter from ambient motion or vibration. Vibration-driven generators based on electromagnetic, electrostatic and piezoelectric technologies have been demonstrated. Among various generator types proposed so far, piezoelectric generator possesses considerable potential in micro system. To overcome low mechanical-to-electric energy conversion, the piezoelectric device should activate in resonance mode in response to external vibration. Normally, the external vibration excretes at low frequency ranging 0.1 to 200 Hz, whereas the resonant frequencies of the devices are fixed as constant. Therefore, keeping their resonant mode in varying external vibration can be one of important points in enhancing the conversion efficiency. We investigated the possibility of use of multi-bender type piezoelectric devices. To match the external vibration frequency with the device resonant frequency, the various devices with different resonant frequency were chosen.

• KIEE International Transactions on Power Engineering
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• v.4A no.3
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• pp.129-133
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• 2004

This paper deals with the design and implementation of a TCSC (Thyristor Controlled Series Capacitor) simulator, which is a module for an analog type power system simulator. Principally, it presents configuration of controller hardware/software and its experimental results. An analog type power system simulator consists of numerous power system components, such as various types of generator models, scale-downed transmission line modules, transformer models, switches and FACTS (Flexible AC Transmission System) devices. It has been utilized for the verification of the control algorithm and the study of system characteristics analysis. This TCSC simulator is designed for 50% line compensation rate and considered for damping resister characteristic analysis. Its power rate is three phase 380V 20kVA. For hardware extendibility, its controller is designed with VMEBUS and its main CPU is TMS320C32 DSP (Digital Signal Processor). For real time control and communications, its controller is applied to the RTOS (Real Time Operation System) for multi-tasking. This RTOS is uC/OS-II. The experimental results of capacitive mode and inductive mode operations verify the fundamental operations of the TCSC.