• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.86.6-86
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• 2001

For discriminating between water and oil, a novel method is proposed in this paper. As a fundamental result, the temperature dependence of ultrasonic travel time of water and oil measured from 5$^{\circ}C$ to 40$^{\circ}C$ at a step of 5$^{\circ}C$ is found as that the ultrasonic travel time of oil increases with increasing temperature, whereas that of water decreases. The proposed method for discriminating between water and oil is based on the opposite temperature dependence of ultrasonic travel time of water and oil. Besides the advantages of non-invasion and on-line measurement, there are no requirements of measuring the temperature of liquid being detected and obtaining previously a large quantity of database, and furthermore, only two times of measurements are ...

• Journal of radiological science and technology
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• v.23 no.2
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• pp.33-37
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• 2000

The authors fabricated ultrasonic transducer with PVDF[poly(vinylidene fluoride)] piezoelectric polymer film. When impulse waves were applied to the PVDF ultrasonic transducer, the dependence of the response properties on the backing material with copper was investigated through not only theoretical calculations using Mason's equivalent circuit but also experimental measurements. The experimental pulse response properties agree with those of the theoretical calculations and the pulses were shorter than those for a PZT transducer. If such short-pulse properties are used in an medical ultrasonic image diagnosis apparatus, the resolution of the apparatus will be improved. When the insertion loss was calculated theoretically to the PVDF ultrasonic transducer, the frequency characteristics of its showed wideband frequency.

• Korean Journal of Materials Research
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• v.3 no.6
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• pp.585-592
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• 1993

The effects of grain size and microstructure on the ultrasonic attenuation was investigated with SCM440 steel quenched and tempered at various temperatures. The ultrasonic attenuation was primarily due to the grain boundary scattering and the ultrasonic attenuation coeffecient increased with increasing grain size. In the meantime, it was found that the ultrasonic attenuation coefficient decreased with increasing tempering temperature. The dependence of ultrasonic attenuation coefficient on the frequency of ultrasonic wave had linear relationship on a log-log scale and was proportional to the Roney's equation.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.668-678
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• 2017

Intermolecular interactions were studied for binary mixtures of 2-propanol + cyclohexane, n-hexane, benzene, toluene, o-, m- and p-xylenes by measuring ultrasonic speeds (u) over the entire range of composition at 298.15 K and 308.15 K. From these results the deviation in ultrasonic speed was calculated. These results were fitted to the Redlich-Kister equation to derive the binary coefficients along with standard deviations between the experimental and calculated data. Acoustic parameters such as excess isentropic compressibility ($K_s^E$), intermolecular free length ($L_f$) and available volume ($V_a$) were also derived from ultrasonic speed data and Jacobson's free length theory. The ultrasonic speed data were correlated by Nomoto's relation, Van Dael's mixing relation, impedance dependence relation, and Schaaff's collision factor theory. Van Dael's relation gives the best prediction of u in the binary mixtures containing aliphatic hydrocarbons. The ultrasonic speed data and isentropic compressibility were further analyzed in terms of Jacobson's free length theory.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.1
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• pp.22-26
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• 2001

The microstructural changes with pearlite formation heat treatment in eutectoid steel(railway steel) consisting of only pearlite structure were evaluated by the ultrasonic attenuation and velocity measurements. The result of this investigation showed a strong linear dependence of ultrasonic attenuation on pearlite interlamellar spacing, and accordingly on fracture strength of the pearlite.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1535-1541
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• 1994

The void content of carbon fiber reinforced composite laminates was determined by the ultrasonic nondestructive technique. The ultrasonic immersion, through-transmission method developed stresses the utilization of spectral analysis and frequency dependence of the attenuation due to porosity. The measured attenuation shows approximately linear behavior over the frequency range investigated. The linear relationship between the void content and the attenuation slop (d $\alpha$/df) is found to hold, but the constant of proportionality is quite different for samples with different pore morphology. The void volume fraction determined by the attenuation slope agreed very well with that obtained by the acid digestion analysis.

• 전기의세계
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• v.30 no.1
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• pp.47-54
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• 1981

The fabrication of Langevin type vibrators producing relatively high sonic and ultrasonic energy is described. The dependence of the acoustic output and the frequency characteristics on the thickness of the steel plates and the pressure at the ceramics are investigated. As results, the acoustic output of Langevin type vibrators are relatively high, and the resonant frequency is decreassed by thickening the steel plates and lowering the pressure at the ceramics. Using these results, sonic and ultrasonic vibrator whose resonant frequency is determined can be designed.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.509-517
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• 2012

In the present study, temperature and frequency dependences of ultrasonic properties such as attenuation coefficient and phase velocity was investigated for six kinds of commercial MC-Nylon polymer samples. The ultrasonic properties of the samples were measured by using a pulse transmission method in water over a broadband frequency range of 2 to 8 MHz. Water temperature was varied from 10 to $60^{\circ}C$ with the $10^{\circ}C$ interval. The attenuation coefficients of the samples increased with the frequency and the exponent n of frequency dependence ranged within 1.16 to 1.44, slightly deviating from the linear dependence (n=1). The phase velocities of the samples exhibited negative dispersion, i.e., decreasing velocity with increasing frequency, except for ivory sample at $60^{\circ}C$. The frequency-dependent phase velocities of the samples showed the decreasing tendency with increasing temperature.

• Macromolecular Research
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• v.12 no.6
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• pp.559-563
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• 2004

Both the ultrasonic velocity at 3 MHz and the absorption coefficient in the frequency range from 0.2 to 2 MHz were measured for aqueous solutions of poly(sodium 4-styrenesulfonate) over the concentration range from 5 to $25\%$ (by weight). The pulse echo overlap method was employed to measure the ultrasonic velocity over the temperature range from 10 to $90^{\circ}C;$ the high-Q ultrasonic resonator method was used for the measurement of the absorption coefficient at $20^{\circ}C.$ The velocities exhibited their maximum values at ca. 55, 59, 63, 67, and $71^{\circ}C.$ for the 25, 20, 15, 10, and $5\%$ solutions, respectively. The velocity increased with respect to the poly(sodium 4-styrene-sulfonate) concentration at a given temperature. A study of the concentration dependence of the both the relaxation frequency and amplitude indicated that the relaxation at ca. 200 kHz is related to structural fluctuations of the polymer molecules, such as the segmental motions of the polymer chains and that the relaxation at ca. 1 MHz resulted from the proton transfer reactions of the oxygen sites of $SO_3.$ Both the absorption and the shear viscosity increase upon increasing the polymer concentration, but they decrease upon increasing the temperature.

• The Journal of the Acoustical Society of Korea
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• v.19 no.4
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• pp.101-106
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• 2000

This study deals with the relationship between the magnitude of ultrasonic nonlinear parameter B/A, sound speed of amount of fat present in biological media for measuring B/A system using a wide band ultrasonic transducer. To represent this case, mixtures of egg white and egg yolk were studied. Even though the differences in density and sound speed of the two egg components were within 1% of each other, B/A were increases parabolically as a function of the fat density, which is not in agreement with the Yoshizumi et al's suggestion. In skim milk that does not contain fat, both the B/A and the sound speed increase with the solubility. It is proposed that protein could affect these values.