• Title, Summary, Keyword: Ultrasonic velocity

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Simultaneous Measurement of Ultrasonic Velocity and Thickness of Isotropic and Homogeneous Solids Using Two Transducers (두개의 탐촉자를 사용한 등방성 균일 고체의 초음파 속도 및 두께 동시 측정법)

  • Lee, Jeong-Ki;Kwon, Jin-O;Kim, Young-H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.19 no.5
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    • pp.363-368
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    • 1999
  • Ultrasonic pulse-echo methods measuring the transit time through specimens have been widely used in determination of ultrasonic velocity and thickness of specimens. Usually, to determine the velocity of the ultrasonic. the transit time of the ultrasonic pulse through specimen is measured by using the ultrasonic measuring equipment such as the oscilloscope including ultrasonic pulser/receiver and the thickness of the specimen is measured by using the length measuring instrument such as micrometer or vernier calipers etc., i. e. each parameter is measured by using each measuring method. In the case of the measuring the thickness of a specimen by using the ultrasonics. the ultrasonic equipments, which measure the thickness, such as the ultrasonic thickness gauge must be calibrated by using the reference block of which the ultrasonic velocity is known beforehand. In the present work, we proposed a new method for simultaneous measurement of ultrasonic velocity and thickness without reference blocks. Experimental results for several specimens show that proposed method have good agreements with those by traditional ultrasonic method.

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A Study on Ultrasonic Technique for Measuring Gas Temperature (기체온도 측정을 위한 초음파 계측에 관한 연구)

  • Yoon, Cheon Han;Choi, Young;Jeon, Heung Shin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.7
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    • pp.893-900
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    • 1999
  • Measuring temperature with ultrasonic wave apparatus is desirable in the cue of gas below $300^{\circ}$ because of the fact that the temperature of gas is the function of only sound velocity. In this study, being used a heatable wind channel and a blower. the variation of temperature is observed in accordance with flow rate(air velocity). The frequency modulation method is used to measure the temperature which is varying in hot air flow up to $100^{\circ}$. The length changed in the position of ultrasonic sensors is considered. Also. the effects of air velocity at the same temperature and various facing angles of ultrasonic sensors are considered. As a result of this study. it has been found that the temperature in gas flow is correctly measured regardless of both the distance of ultrasonic sensors and the variation of air velocity. and that there is just a little influence of facing angles.

Non-Destructive Detection of Hydride Blister in PHWR Pressure Tube Using an Ultrasonic Velocity Ratio Method

  • Cheong Yong-Moo;Lee Dong-Hoon;Kim Sang-Jae;Kim Young-Suk
    • Nuclear Engineering and Technology
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    • v.35 no.5
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    • pp.369-377
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    • 2003
  • Since Zr-2.5Nb pressure tubes have a high risk for the formation of blisters during their operation in pressurized heavy water reactors, there has been a strong incentive to develop a method for the non-destructive detection of blisters grown on the tube surfaces. However, because there is little mismatch in acoustic impedance between the hydride blisters and zirconium matrix, it is not easy to distinguish the boundary between the blister and zirconium matrix with conventional ultrasonic methods. This study has focused on the development of a special ultrasonic method, so called ultrasonic velocity ratio method for a reliable detection of blisters formed on Zr-2.5Nb pressure tubes. Hydride blisters were grown on the outer surface of the Zr-2.5Nb pressure tube using a cold finger attached to a steady state thermal diffusion equipment. To maximize a difference in the ultrasonic velocity in hydride blisters and the zirconium matrix, the ultrasonic velocity ratio of longitudinal wave to shear wave, $V_L/V_S$, has been determined based on the flight time of the longitudinal echo and reflected shear echo from the outer surface of the tubes. The feasibility of the ultrasonic velocity ratio method is confirmed by comparing the contour plots reproduced by this method with those of the blisters grown on the Zr-2.5Nb pressure tubes.

Ultrasonic Characterization of Fluid Mud: Effect of Temperature (부유퇴적물의 초음파 특징: 온도의 효과)

  • Kim, Gil-Young;Kim, Dae-Choul;Kim, Jeong-Chang
    • The Journal of the Acoustical Society of Korea
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    • v.23 no.4E
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    • pp.140-145
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    • 2004
  • A laboratory study was carried out to investigate the change of ultrasonic velocity as a function of temperature for fluid mud (i.e., suspension). Pulse transmission technique with ultrasonic wave was used for ultrasonic velocity measurement. The five samples for fluid mud were prepared for concentration range of $30.6{\%}\;(1.24\;g/cm^{3}\;in\;density),\;23.3{\%}\;(1.19\;g/cm^{3}),\;11.5{\%}(1.10\;g/cm^{3}),\;7.8{\%}\;(1.08\;g/cm^{3}),\;and\;3.8{\%}\;(1.05\;g/cm^{3})$ by weight. The ultrasonic velocity in fluid mud was investigated to increase $(approximately\;2.83\;to\;4.95\;m/s/^{\circ}C)$ with increasing temperature, due to the effect of viscosity and compressibility of water with changing temperature. But the increasing rate tends to decrease at temperature higher than $30^{\circ}C,$ caused by the effect of viscosity. The concentration of fluid mud more affect to the ultrasonic velocity at higher temperature range than that at lower temperature. Overall the temperature effect on the ultrasonic velocity in fluid mud was a similar rate as for distilled water and seawater, suggesting fluid mud significantly depends on the behavior of water.

Study on Smart Cooling Technology by Acoustic Streaming Generated by Ultrasonic Vibration Using 3D PIV (3차원 PIV를 활용한 초음파 진동에 의해 발생된 음향 유동을 이용한 스마트 냉각법 연구)

  • Lee, Dong-Ryul;Loh, Byoung-Gook;Kwon, Ki-Jung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.11
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    • pp.1078-1088
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    • 2010
  • In order to analyze the quantitative characteristics of acoustic streaming, experimental setup of 3-D stereoscopic PIV(particle imaging velocimetry) was designed and quantitative ultrasonic flow fields in the gap between the ultrasonic vibrator and heat source were measured. Utilizing acoustic streaming induced by ultrasonic vibration, surface temperature drop of cooling object was also measured. The study on smart cooling method by acoustic streaming induced by ultrasonic vibration was performed due to the empirical relations of flow pattern, average flow velocity, different gaps, and enhancement on cooling rates in the gap. Average velocity fields and maximum acoustic streaming velocity in the open gap between the stationary cylindrical heat source and ultrasonic vibrator were experimentally measured at no vibration, resonance, and non-resonance. It was clearly observed that the enhancement of cooling rates existed owing to the acoustic air flow in the gap at resonance and non-resonance induced by ultrasonic vibration. The ultrasonic wave propagating into air in the gap creates steady-state secondary eddy called acoustic streaming which enhances heat transfer from the heat source to encompassing air. The intensity of the acoustic streaming induced by ultrasonic vibration experimentally depended upon the gap between the heat source and ultrasonic vibrator. The ultrasonic vibration at resonance caused the increase of the acoustic streaming velocity and convective heat transfer augmentation when the flow fields by 3D stereoscopic PIV and temperature drop of the heat source were measured experimentally. The acoustic streaming velocity of air enhancement on cooling rates in the gap is maximal when the gap agrees with the multiples of half wavelength of the ultrasonic wave, which is specifically 12 mm.

Effect of Curing Conditions on the ASR of Lightweight Aggregate Concrete (양생조건이 경량골재 콘크리트의 ASR에 미치는 영향)

  • 성찬용;김성완;민정기
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.35 no.4
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    • pp.38-46
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    • 1993
  • This study is to analyze effect of exposure environment and mode of ASR on the engineering properties of synthetic lightweight aggregate concrete, such as dynamic modulus of elasticity and ultrasonic pulse velocity. The results of this study are summarized as foflows ; 1. The expansion rate of each exposure environment in 380$^{\circ}$C and NaCI 4% solution was shown higher than in 20$^{\circ}$C and normal water. The expansion rate of each exposure mode was largely shown in order of fjill immersion, wetting/drying, half immersion. 2. The dynamic modulus of elasticty and ultrasonic pulse velocity of each exposure environment in 38$^{\circ}$C and NaCl 4% solution was shown less than in 20$^{\circ}$C and normal water. The dynamic modulus of elasticity and ultrasonic pulse velocity of each exposure mode was shown smaller in order of full immersion, wetting/drying, half imersion.3. The relation between dynamic modulus of elasticity and ultrasonic pulse velocity was highly significant. The dynamic modulus of elasticity was increased with increase of ultrasonic pulse velocity. The decreasing rate of the dynamic modulus of elasticity was shown 2.1~3.4 times higher than the ultrasonic pulse velocity at each age, exposure environment and mode, respectively. 4. The expansion of each exposure environment and mode was increased with increase of curing age. The dynamic modulus of elasticity and ultrasonic pulse velocity of those concrete was increased with increase of curing age. At the curing age 28 days, the highest properties was showed at each type concrete, it was gradually decreased with increase of curing age. Specially, at the curing age 98 days of full immersion, the rate of expansion of type D was shown 3.95 times higher than the type A. But the dynamic modulus of elasticity and ultrasonic pulse velocity was decreased 17% and 8.3%.

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Ultrasonic Nondestructive On-Site Evaluation of Decks in-Service (초음파 비파괴시험법을 이용한 데크재의 현장평가)

  • Oh, Sei-Chang
    • Journal of the Korean Wood Science and Technology
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    • v.43 no.4
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    • pp.486-493
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    • 2015
  • The ultrasonic nondestructive test (NDT) was applied to deck in-service to inspect and evaluate the performance of decking materials using ultrasonic pulse velocity. First, the measuring method between direct and indirect method according to transducer arrangement was studied. Second, the ultrasonic pulse velocity of decks in-service was compared with the passage of time. Finally, the change of ultrasonic pulse velocity was evaluated to expect service life of decking materials. The results of comparison between direct and indirect method was statistically insignificant and the ratio of direct to indirect method was 1.02. 1.05 respectively. The ultrasonic pulse velocity of decks in-service was decreased as the passage of time and the linear relationship in the ultrasonic pulse velocity to passage of time was found. From the results, The ultrasonic NDT will be helpful as an efficient method of on-site management of decks in-service.

A New Strength Equation of Concrete by Ultrasonic Pulse Velocity Test (초음파시험법에 의한 콘크리트의 강도 추정)

  • Yoo Jae-Eun;Park Song-Chul;Kim Min-Su;Kwon Young-Wung
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.129-132
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    • 2004
  • This study concerns the new strength equation of concrete by ultrasonic pulse velocity test. There are not only few estimate strength equations of concrete by ultrasonic pulse velocity test, but also many problems to apply them because of time, cost, easiness, structural damage, reliability and so on. For this study, there performed a series of test and proposed equations as follows; $$Linear\;:\;f_{kc}=65.43Vp-207.18\;r^2=80.8\%$$ $$Quadratic\;:\;f_{ck}=42.35Vp^2-250.71Vp+378.8\;r^2=83.7\%$$ here, fck : Estimated compressive strength of concrete by MPa Vp: Ultrasonic Pulse Velocity of concrete by km/sec.

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A New Strength Equations of Concrete by Ultrasonic Pulse Velocity Test (콘크리트의 초음파속도 시험식 제안)

  • Yoo Jae Eun;Park Song Chul;Kim Min Su;Kwon Young Wung
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.619-622
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    • 2005
  • This study concerns the new strength equation of concrete by ultrasonic pulse velocity test. There are not only few estimate strength equations of concrete by ultrasonic pulse velocity test, but also many problems to apply them because of time,. cost, easiness, structural damage, reliability and so on. For this study, there performed a series of test and proposed equations as follows; Linear: ${\Large f}_{ck}=-193.15+60.97Vp\;r^2=77.9\%$ Quadratic : ${\Large f}_{ck}=276.85-189.64Vp+33.22Vp^2\;r^2=80.3\%$ here, $f_{ck}$ : Estimated compressive strength of concrete by MPa Vp : Ultrasonic Pulse Velocity of concrete by km/sec

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Measurement of Ultrasonic Wave Velocity Changes in Silica-Sand Specimens with Voids (공극을 포함한 실리카샌드 시편의 초음파 속도변화 측정)

  • Kim, Dae-You;Rhim, Hong-Chul;Cho, Youn-Jin
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.48-49
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    • 2017
  • In order to examine the effect of voids on the ultrasonic wave velocity, specimens made of Silica-Sand with voids were prepared for the measurements. The volume fraction of 0, 15, and 30% of voids were used to compare the differences. Because of its more homogeneous distribution of materials properties, the Silica-Sand specimens were used, as compared to mortar specimens. The results showed clear change in ultrasonic wave velocity with different volume fraction of voids. This result is to be used for the estimation of the integrity of concrete structures using ultrasonic wave velocity method as nondestructive testing.

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