• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.422-427
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• 2018

The purpose of this study is to investigate the effect of acoustic radiation force on the standing wave acoustic levitation phenomenon, which is the levitation of small objects near the pressure node of the standing wave, using the Bernoulli principle. The source and scheme of the acoustic radiation force, which is the cause of the levitation, are conceptually explained through comparison with the graph of the acoustic radiation force versus the distance from the transducer. A series of experiments supporting this explanation was performed with a BLT(Bolt-clamped Langevin Type) ultrasonic transducer to confirm that the objects are floating near the pressure nodes and that it satisfies the condition for the standing wave formation when the object is levitating. Furthermore, the vertical alignment of floating objects, which is a characteristic of standing wave acoustic levitation phenomenon, could be explained.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1995.10a
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• pp.120-121
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• 1995

In the design of mixed type breakwater, the most important factor to be considered is the wave pressure. In particular, the standing wave pressure has a significant effect on the vertical wall breakwater or mixed type breakwater. Many wave pressure formulas were developed and the Goda's formula［1］ was very frequently used among them by the coastal engineers due to its simplicity and accuracy. (omitted)

• Journal of Biosystems Engineering
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• v.37 no.2
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• pp.113-121
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• 2012

Purpose: Particle separation in solution is one of important process in a unit operation as well as in an extract preparation for biosensors. Contrary to centrifuge-type of mesh-type filter, using an ultrasonic standing wave make the filtering process continuous and free from maintenance. It is needed to investigate the characteristics of particle movement in the ultrasonic standing wave field. Methods: Through the computer simulation the effects of major design and driving parameters on the alignment characteristics of particles were investigated, and a cylindrical chamber with up-stream flow type was devised using two circular-shape PZTs on both sides of the chamber, one for transmitting ultrasonic wave and the other for just reflecting it. Then, the system performance was experimentally investigated as well. Results: The speed of a particle to reach pressure-node plane increased as the acoustic pressure and size of particle increased. The maximum allowable up-stream flow rate could be calculated as well. As expected, exact numbers of pressure-node planes were well formed at specific locations according to the wavelength of ultrasonic wave. As the driving frequency of PZT got close to its resonance frequency, the bands of particles were observed clearer, which meant the particles were trapped into narrower space. Higher excitation voltages to the PZT produced a greater acoustic force with which to trap particles in the pressure-node planes, so that the particles gathered could move upwards without disturbing their alignments even at a higher inlet flow rate. Conclusions: This research showed the feasibility of particle separation in solution in the continuous way by an ultrasonic standing wave. Further study is needed to develop a device to collect or harvest those separated particles.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.661-666
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• 2000

Traveling wave on the structure can be generated by superposing two standing waves. Precise matching of the amplitudes and phase shift between two standing waves in time and space is the key to the success of generating a traveling wave. The principle of generating a traveling wave on the structure is utilized in the construction of linear and rotary type ultrasonic motors. This paper demonstrates experimentally generating a traveling wave on the simply supported beam.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1994.10a
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• pp.79-90
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• 1994

The goal of this research is to get a measuring system for absorption characteristics of electromagnetic wave absorbers in ferrite type which are lat grid-type special type etc. It is however very difficult to measure the absorption characteristics as in low frequency as in 30 MHz, To solve the problem therefore we propose a standing wave method and a measurement method in time domain using parallel striplines construct the measuring system and measure the characteristics of ferrite microwave absorbers in grid type using the proposed measuring system.

• The Journal of the Acoustical Society of Korea
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• v.20 no.8
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• pp.38-43
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• 2001

We developed a new standing wave type ultrasonic linear motor that can be driven bi-directionally. The operation principle of the motor was derived in an analytical form and the detailed structure was designed by the finite element method. Based on the design, a motor sample and a driving circuit were fabricated, and validity of the structure was verified through experiments.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.303-306
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• 2011

An experimental study has been conducted to investigate the effects of an ultrasonic standing-wave field to the behavior of methane/air premixed flame. Visualization technique utilizing the schlieren method was employed for the observation of premixed flame behavior. The shape of flame front and local flame velocity were measured according to the variation of reactants pressure and chamber opening/closing condition. The flame front was distorted and severely deformed to a lotus-type flame by the interaction of ultrasonic standing-wave and the reflection wave coming from an end wall of reactor.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.124-125
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• 2000

We introduce a scheme with a maximized efficiency of detecting atoms passing through an optical standing-wave mode cavity. Consider a standing-wave optical cavity illuminated by a weak probe beam through one of its mirrors where the transmission through the other mirror is monitored by a photodetector. If an atom is put in the cavity, the atom-cavity coupling shifts the resonance frequency of the system via the so-called normal mode splitting, and thereby the transmission power will drop. In fact, this type of atom detection scheme has been used in recent single atom trap experiments In practice, however, the field in a standing-wave mode will have a geometrical structure having nodes and antinodes that when the atom traverses the cavity through one of the nodes, there will be no such effect of atom-field interaction. (omitted)

• Journal of the Korean Institute of Navigation
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• v.17 no.3
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• pp.77-83
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• 1993

The goal of this research is to get a measuring system for absorption characteristics over the frequency band with 30MHz to 1, 000MHz concerning the ferrite electromagnetic wave absorbers, for example, grid-type and sintered flat type, etc. It is, however, very difficult to measure the absorption characteristics as in low frequency as in 30 MHz. In this research, therefore, we propose a standing wave method using parallel striplines, fabricate the measuring system, and measure the characteristic of ferrite microwave absorbers using the proposed mea-suring system.

• 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.