• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.328-330
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• 1994

The Ultrasonic motor(USM) has many good characteristics such as high torque at low speed range, large holding torque based upon frictional force, high speed response, flexible free ferns, compactness in size, low magnetic noise and silentness in motion. Because of having low speed rotation, USM is good as an actuator of a small size direct drive (DD) manipulator. The acturators for the DD manipulators must have good controllability on the speed and torque from zero to maximum value continuously. New method was developed for speed and torque control by the phase difference control of the two-phase driving signals of the motor. Then rule adjustable compliant and dumped motion was realized on the output shaft of the motor by PD control of the output shaft angle.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.525-528
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• 2002

The speed of sound, transmission coefficient, and attenuation are measured around the center frequency 1 and 2 MHz in solid materials such as bone, sediment, rubber, and Lucite materials. Common and different characteristics of such materials in the sound speed, transmission coefficient, and attenuation are discussed. Ambiguities in estimating such acoustic characteristics we also addressed. Ultrasonic properties of the first and second kind waves are clarified for different materials. Discussions are concentrated on classes of sound speed, broadband ultrasonic attenuation (BUA), and correlations of sound speed and BUA with apparent density. New correlations of inverse sound speed square and BUA with apparent density are suggested.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1327-1332
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• 2000

Ultrasonic motors have an advantage over conventional electro-magnetic motors because of its excellent characteristics, such as high torque, low speed output, compact size, excellent controllability and, above of all, quite operation. The principle of operation of ultrasonic motors is to generate gross mechanical motion through the amplification and repetition of micro-deformations of active materials. A brief description of working principle and methods of analysis of dynamic behaviors of ultrasonic motors are given for the extended research and development activities anticipated in the mechanical engineering community.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.249-255
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• 2006

In this paper, we study the river level/velocimetry measuring system using the ultrasonic sensor to acquire the more precise data from the river circumstance in rainy season. We design the two ultrasonic sensor system to calculate the water level and surface current speed of the river using the dedicated hardware and software. We investigate the validity and effectiveness of the proposed system which applied to the real river environment monitoring system that will be extended to the GIS.

• Journal of Conservation Science
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• v.38 no.4
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• pp.314-326
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• 2022

Investigation of conservation status, optical survey, infrared thermography, and ultrasonic examination were performed on Avalokitesvara Bodhisattva mural and Buddhist Monk Bodhidharma mural to determine the conservation status and physical properties. As a result of investigation of conservation status, the types of damage are largely divided into the wall and finishing layer damage, painting layer degradation, damage due to restoration materials, stains and contamination, and biological damage. As a result of the optical survey, drawing, stains, and repainted site were confirmed. Result of the infrared thermography, the delamination of the finishing layer was confirmed, and some locations and shapes of the wooden lath inside the wall were identified. The result of the 3D scanning, the deviation, and the separation of the wall was confirmed. As a result of ultrasonic examination, it was confirmed that the physical properties of the mural were identified and the ultrasonic speed was relatively low due to physical damage such as delamination and exfoliation of the finishing layer and cracking. Ultrasonic speed values were also high in some wall cracks or delamination, and it was confirmed by the infrared thermography results that the wooden lath inside the wall was located in those parts. It was possible to understand that the wooden lath inside the walls affects the ultrasonic speed during the ultrasonic examination. Therefore, management through periodic inspection of the relevant elements is necessary, and a countermeasure for damage that may occur in the future should be prepared along with intensive monitoring of the major damage identified in this diagnosis result.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1638-1644
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• 2005

This paper suggests fur the study on a fluid velocity measuring system using ultrasonic transducer. In general, the time difference method to measure the distance between transducers has been known. In this paper, the practical technology for manufacturing ultrasonic flow meter system is studied using the time difference method. The ultrasonic transducer was designed and manufactured. The transmission and receiving algorithm for ultrasonic signal was studied. The ultrasonic flow measuring system was experimented in laboratory using a water reservoir for verifying the distance measuring accuracy. Finally, it was tested in flow calibration laboratory for the velocity measuring performance. The system, designed in this study, showed 0.3 mm resolution in distance measurement. For precise flow measurement, a high speed triggering algorithm is required for ultrasonic signal receiving.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.6
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• pp.1281-1290
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• 2001

A study on the fluid flow with ultrasonic forcing is carried out to obtain data for the turbulence enhancement. A large water tank is made of the transparent acrylic plates and a horizontal flow field is given by setting two acrylic tubes to face mutually on a horizontal line. A 2-dimensional PlV system which is composed of a continuous-output 4W Argon-ion laser, a high-speed video camera, a PC based by an image grabber and a high resolution monitor is used to investigate characteristics of the complex turbulence flow field. And a 2MHz ultrasonic transducer is used fur ultrasonic vibration forcing. Some experiments are carried out at Reynolds numbers of 2,000 and 4,000 and at 7 angles of ultrasonic incidence. In results, the flew velocity vector distribution, kinetic energy and turbulence intensity in both cases of with and without ultrasonic forcing are examined, compared and discussed by using PIV measurement. It is clarified that the ultrasonic forcing into flow field is valid to obtain the turbulence enhancement.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.207-211
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• 2010

In this paper, the fluid AID(acoustic inspection device) was developed to measure SOS(speed of sound) since fluids used in most of industrial fields have different properties and its equipment is highly expensive. From AID developed, it is intended to get potentially the capability to distinguish the kind of fluid using the measurement by the SOS at various fields. In order to measure the sound speed of specific fluids, the measurement system and ultrasonic sensors are composed. The fluid used in the experimental work are soybean oil, glycerin, diesel oil and the error of time difference due to the container wall is extracted for preliminary experiment. As results, the variations of sound speed according to the temperature change of target fluid were analyzed and the polynomial equations were proposed.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.68-71
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• 2001

This paper has been studied for a comparison of the propagation and noise characteristics between ultrasonic and electromagnetic wave for the high speed communication of the short range telemetry. We analyze the propagation depth of electromagnetic and ultrasonic wave by skin depth effect and by ultrasonic loss ratio. We also studied several effects such as near field effect in electromagnetic wave and Rayleigh scattering noise of ultrasonic wave, etc. We show the experimental results of their propagation loss and modulation experiments in water. The experimental results show that both method is good for the implementation of short range telemetry.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.274-275
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• 2006

A linear ultrasonic motor was designed by a combination of the longitudinal and bending mode. Linear ultrasonic motors are based on an elliptical motion on the surface of elastic body, such as bar or plates. The corresponding eigen-mode of one resonance frequency can be excited twice at the same time with a phase shift of 90 degrees in space and time. That is excite symmetric and anti-symmetric modes. Then it determines the thrust and speed of the motor. Linear ultrasonic motors are investigated experimentally in according to be fabricated a general classification to motor structure and material characteristic. There was the first to simulate as use of finite element analysis ANSYS 9.0. The AL-T2W8-ARM14-LEG18-ANGLE80 motor has a maxim efficiency 17 [%] under the speed 0.14 [m/s], thrust 345 [gf] and preload 280 [gf], operating frequency is 57.6 [kHz].