• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.280-285
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• 2000

The conventional ultrasonic linear motors developed so far utilize a standing wave and are of a pi-type or a hybrid transducer type structure. Traveling wave type bi-direction linear motors have not been developed yet. This paper describes design of a new bi-directional ultrasonic linear motor working by means of a traveling wave. With the finite element method we design and verify validity of the new structure. And we determine its optimal structure size of design variables material and boundary conditions for proper generation of the traveling wave.

• Geomechanics and Engineering
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• v.17 no.6
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• pp.597-606
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• 2019

Ultrasonic Time-of-Flight Diffraction (TOFD) techniques are useful methods for non-destructive evaluation of fracture characteristics. This study focuses on the reliability and accuracy of ultrasonic diffraction methods to estimate the depth of rock fractures. The study material includes three different rock types; andesite, basalt and ignimbrite. Four different ultrasonic techniques were performed on these intact rocks. Artificial near-surface fracture depths were created in the laboratory by sawing. The reliability and accuracy of each technique was assessed by comparison of the repeated measurements at different path lengths along the rock surface. The standard error associated with the predictive equations is very small and their reliability and accuracy seem to be high enough to be utilized in estimating the depth of rock fractures. The performances of these techniques were re-evaluated after filling the artificial fractures with another material to simulate natural infills.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1259-1263
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• 2004

In this paper, the optimum design of ultrasonic dry cleaning head was investigated. The transducer instead of mechanical dynamic structure was used to generate ultrasonic wave and the horn-shape amplifier was utilized to solve the energy decaying problem of ultrasonic wave with propagating it through the media. The analyses of ultrasonic wave and a fluid for the selected structure of a cleaning head were carried out using SYSNOISE and ANSYS simulators, respectively. Based on simulator results, the distance between a horn and the substrate of 4 mm and the horn diameter of 10 mm were determined to maximize the energy of ultrasonic waves. The cooling structure was also considered to reduce the heat from the transducer and the horn. The equivalent circuit for the fabricated horn was deduced from HP4194A impedance/gain/phase analyzer and the frequency of an ultrasonic wave of 20.25 kHz was confirmed using the parameters of the equivalent circuit.

• Journal of Sensor Science and Technology
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• v.12 no.2
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• pp.95-101
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• 2003

Ultrasonic transmitter used for scale prevention in boiler or heat exchanger is composed of the magnetostrictive material which transforms electric energy into ultrasonic wave and the horn which amplifies generated ultrasonic wave and transfers it into medium loaded. In this paper, we have performed the shape design for magnetostrictive material and analyzed a few type of horns which amplify generated ultrasonic wave and found each solution theoretically. Final length of the horn has been determined by measuring the sound pressure in medium between theoretical value and experience data. At last we have given the results of our study for the effects of ultrasonic wave irradiated by manufactured ultrasonic transmitter on preventing scale deposition on test pipe under the similar condition to boiler.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.6
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• pp.580-584
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• 2006

Material information for environment may be useful to accomplish mobile robot localization. A procedure to classify a set of indoor materials (glass, steel, wood, aluminum and concrete) with the reflected signal of ultrasonic sensor is proposed in this paper. The main idea is to use material-specific reflection characteristics for the recognition of material type. To achieve the classification task, we modeled reflected signal as a maximum amplitude with respect to distance. In this way, we can generate echo signal models for the given materials and these models are used to compare with the current sensor reading. The experimental results show that the proposed method may give material information during map building task of mobile robot.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.186-192
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• 2022

Flow accelerated corrosion (FAC) is a type of pipe corrosion in which the pipe thickness decreases depending on the fluid flow conditions. In nuclear power plants, FAC mainly occurs in the carbon steel pipes of a secondary system. However, because the temperature of a secondary system pipe is over 150 ℃, in situ monitoring using a conventional ultrasonic non-destructive testing method is difficult. In our previous study, we developed a waveguide ultrasonic thickness measurement system. In this study, we applied a waveguide ultrasonic thickness measurement system to monitor the thinning of the pipe according to the change in pH. The Korea Atomic Energy Research Institute installed FAC-proof facilities, enabling the monitoring of internal fluid flow conditions, which were fixed for ~1000 h to analyze the effect of the pH. The measurement system operated without failure for ~3000 h and the pipe thickness was found to be reduced by ~10% at pH 9 compared to that at pH 7. The thickness of the pipe was measured using a microscope after the experiment, and the reliability of the system was confirmed with less than 1% error. This technology is expected to also be applicable to the thickness-reduction monitoring of other high-temperature materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.350-355
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• 1997

A new magnetic field measuring system with induced coil is reported. This system consists of air-cared coil that is forced by the ultrasonic transducer. Induction voltage of coil is proportional to the DC magnetic field and the driving frequency of ultrasonic transducer by the principle of Faraday's law. The experimental measuring system is setup, and the possibility of a new magnetic field sensors is confirmed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.300-302
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• 1999

The standing waves of the fourth bending mode of vibration and first longitudinal mode of vibrator were utilized to construct a ultrasonic linear motor. The geometrical dimensions of the vibrator were determined by Euler-Bernoulli theoty. FEM(finite element method) employed to calculate the vibration mode of the metal-piezoceramic composite thin plate vibrator. ANSYS was used to design positions of the projections and calculate displacement of vibrator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.129-131
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• 1999

Driving generator of USMs(ultrasonic motors) with low noise, high efficiency was designed and fabricated. It was focused on merits such as size-reduction, thermal resistance, To control revolution speed, input frequency was varied. Output of generator had frequency range of 39.1 ∼ 43.5 MHz and voltage of 120 V. USM with resonant frequency 40.3 kHz exhibited a maximum torque of 2.5 kg $.$ cm and a maximum revolution speed of about 130 rpm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.168-171
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• 2000

Underwater acoustic communications have made considerable advances in the past decade. The purpose of this paper is to achieve the underwater communication by ultrasonic sensors and to investigate conditions of good underwater acoustic communicators. As a result of this experiments, the ultrasonic sensors, MA40E7R/S, made by Nicera can be used as ultrasonic transducers for underwater communication using AM(Amplitude Modulation) signal and Transmission Loss is 17.328[dB] at 65[cm]. To make a good underwater communicator, proper diameter of disk PZT transduers is the one of most important factors, because radiation of acoustic wave depends on proper diameter of transduers and the transmission loss strongly depends on the spreading loss.