• The Journal of the Acoustical Society of Korea
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• v.11 no.4
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• pp.45-52
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• 1992

• Journal of the Korean earth science society
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• v.24 no.6
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• pp.549-557
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• 2003

Surface wave exploration method has many advantages over other conventional exploration methods. Only limited accumulation of the study results has been made due to the recent development of the method. In this study the characteristics of the phase dispersion curves of four sites with different geo-technical properties have been identified. A generalized inversion method was used to obtain the shear wave velocity profiles of the study areas. The shear wave velocity profiles were compared with the columnar sections of the boreholes at the sites. This study shows that the rapid changes in the shear wave velocities are consistent with the changes in the sedimentary or lithologic faces found in the borehole measurements. This implicates that the surface wave exploration method could be used to identify changes in the physical properties of sediments or rocks.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.9-23
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• 2010

In current design practice, the shear wave velocity (Vs) of the core and rock-fill zone of a dam, one of the characteristics essential for seismic response design, is seldom determined by field tests. This is because the borehole seismic method is often restricted in application, due to stabilisation activities and concern for the security of the dam structure, and surface wave methods are limited by unfavourable in-situ site conditions. Consequently, seismic response design for a dam may be performed using Vs values that are assumed, or empirically determined. To estimate Vs for the core and rock-fill zone, and to find a reliable method for measuring Vs, seismic surface wave methods have been applied on the crest and sloping surface of the existing 'M' dam. Numerical analysis was also performed to verify the applicability of the surface wave method to a rock-fill dam. Through this numerical analysis and comparison with other test results, the applicability of the surface wave method to rock-fill dams was verified.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.512-513
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• 2014

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.4
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• pp.241-250
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• 1997

The velocity dispersion of surface acoustical wave(SAW) of Si layer/mesh Au/Si substrate was measured by the frequency analysis technique of backward radiation at liquid/solid interface. The difference of backward radiation patterns depending on used transducers (2, 5, 10MHz) confirmed that the backward radiation phenomenon was caused by the energy radiation from SAW generated in surface region. An ultrasonic goniometer was constructed to measure continuously the angular dependence of backscattered intensity. The angular dependences of backward radiation(5MHz) were measured for Ni layer/Al substrate specimens that were bonded by epoxy involving different content of Cu powder. It was known that the width and pattern of backward radiation had informations such as the velocity dispersion, bonding quality and structure of surface region.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.5
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• pp.437-443
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• 2010

SAW device is widely used as band pass filters, chemical or physical sensors, and actuators. In this paper, we propose the capacitive gap measurement system with high precision using SAW device. The research process is mainly composed of theoretical and experimental part. In the theoretical part, equivalent circuit model was used to predict the SAW response by the change of load impedance. In the experimental part, commercialized capacitor was used to see the SAW response by the change of load capacitance to check the feasibility as a sensor unit. After that, experimental setup to measure and adjust the gap was made and the SAW response by the change of gap which caused the capacitance change was measured. Finally, resolution and stroke was decided compared with the signal change and basic measurement noise level.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.8 no.4
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• pp.151-155
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• 1983

In this paper, it is studied a novel SAW oscillator by applicating SAW delay characteristics, which can be variable its frequencies by consiting of two output IDT(Inter-Digital Transducer) without external filtering and resonating circuits. The results of experiments showed the temperature characteristics of AT-cut quartz which has been used as frequency-determing substrate of SAW oscillator was good. Though the variable frequencies range was narrow but the experiments showed the possibility to broaden its frequencies range by design of SAW device, and also confromed the stability of fundamental wave oscillating in high frequency range.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.1
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• pp.106-113
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• 2009

This paper presents a surface acoustic wave(SAW) micro-electro-mechanical-systems(MEMS) interdigital transducer (IDT) gyroscope with 80MHz central frequency on a $128^{\circ}\;YX\;LiNbO_3$, which is consisted of a two-port SAW resonator, metallic dots and dual delay lines for the sensor and reference oscillators. Reason for using two delay line oscillators is to extract the gyroscope effect by comparing the resonant frequencies between two oscillators and to compensate the temperature effect. Based on the coupling of modes(COM) simulation, an 80MHz two ports SAW resonator and dual delay line were fabricated and characterized by the network analyzer. Obtained sensitivity was $109Hz/deg{\cdot}s^{-1}$ in the angular rate range of $0{\sim}1000deg/s$. Good Linearity and superior directivity were observed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.11
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• pp.1128-1133
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• 2008

Cellulose based electroactive paper(EAPap) has been developed as a new smart material due to its advantages of piezoelectricity, large displacement, low power consumption, low cost and flexibility. EAPap can be used for a surface acoustic wave (SAW) device using the piezoelectric property of EAPap, resulting in the cost effective and flexible SAW device. In this paper, inter digit transducer(IDT) structure using lift-off technique with a finger gap of 10mm was used for micro fabrication of the cellulose EAPap SAW devices. The performance of IDT patterned SAW device was characterized by a Network Analyzer. The feasibility of cellulose EAPap as a potential acoustic device was presented and explained.

• Journal of the Korean Institute of Telematics and Electronics
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• v.10 no.3
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• pp.53-60
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• 1973

Calculations of the temperature coefficients of the elastic surface wave velocity and delay time were performed for the propagation along the X axis of rotated Y cut plane of the LiNbO3 and LiTaO3. Measurements of the temperature dependence of delay time of the elastic surface wave were also performed for the propagation along the X axis of a 130" rotated Y cut plane of the LiNb03 at the temperature range from liquid He to room temperature. Experimental value 70$\times$10-6/$^{\circ}C$ of the temperature coefficient of the delay time of the elastic surface wave agrees well with the calculated value 72.7$\times$10-a/$^{\circ}C$. The temperature coefficient of delay time of elastic surface wave propagating along the X axis of a 130$^{\circ}$ rotated Y cut plane o( the LiNbO3 is approximately 16$\times$10-6/$^{\circ}C$ at the near temperature of liquid He.d He.