• Title, Summary, Keyword: Ultrasonic velocity

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Performance Evaluation of the Velocity Profile Integration for the Multi-Path Ultrasonic Flowmeter in Symmetric & Asymmetric Flow Field (대칭 및 비대칭 유동장에서 다회선 초음파 유량계의 유속분포 적분 방법 평가)

  • Kim, Joo-Young;Kim, Kyung-Jin;Park, Sung-Ha
    • 유체기계공업학회:학술대회논문집
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    • pp.370-377
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    • 2002
  • Generally, the system of calculation for the multi-path ultrasonic flow meters can be divided into two methods by how to get the mean velocity, namely, weighting and direct method. Weighting-method derive the mean velocity through modeling in theoretical velocity profile. Direct-method derive the mean velocity though actual flow distribution. The system of calculation varies with maker's transducer configuration and integration method. Each system has merits and demerits. This paper describes the system of integration that calculates line velocity over cross-section of the circular pipe. Flow rate mr discussed in this paper is a difference between theoretical flow rate and integrated flow rate according to values of Reynolds number in symmetric flow field or theoretical flow rate and integrated flow rate according to rotated model in asymmetric flow field.

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Evaluation Technique of Concrete Strength Using Impact-Resonance and Combined Method (충격공진법 및 복합법을 이용한 콘크리트의 강도 평가 기법)

  • 이광명;이회근;김동수;김지상
    • Journal of the Korea Concrete Institute
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    • v.11 no.4
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    • pp.157-167
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    • 1999
  • Among several non-destructive testing methods, ultrasonic pulse velocity method and rebound index method have been widely used for the evaluation of concrete strength. However, such methods might not provide accurate estimated results since factors influencing the relationship between strength and either ultrasonic pulse velocity or rebound index are not considered. In this paper, the evaluation method of concrete strength using rod-wave velocity measured by impact-resonance method is proposed. A basic equation is obtained by the linear regression of velocity vs, strength data at specific age and then, aging factor is employed in the equation to consider the difference of the increasing rate between wave velocity and strength. Strengths predicted by the proposed equation agree well with test results. Furthermore, the combined method of rod-wave velocity and rebound index is proposed.

Measurement of Ultrasonic Speed for Evaluating Compressive Strength of Solidified Low & Intermediate-Level Radioactive Wastes (중·저준위 방사성폐기물 고화체의 압축강도 평가를 위한 초음파속도 측정)

  • Moon, Gyoon Young;Lee, Tae Hun;Moon, Yong Sig
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.7 no.4
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    • pp.26-30
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    • 2011
  • In order to ship low & Intermediate level radioactive waste drums, which have been temporarily stored on site, to a disposal facility, their physical and chemical properties should be evaluated and proven to meet the acceptance guideline prior to their shipment. Ultrasonic velocity method, which has been used to estimate the strength of concrete, can be suggested to evaluate the compressive strength of solidified radioactive waste, which is one of the evaluated properties. The strength is estimated from acoustic velocity. However, a guided wave traveling along a drum is generated when applying ultrasonic method to the drum, and this makes it difficult to analyze the signal due to overlap between transmitted wave through the contents in drum and the guided wave. This paper reported feasibility of ultrasonic method to evaluate of the compressive strength of the solidified LLW. It is observed that the guide wave is greater than transmitted wave, and ultrasonic velocity could be estimated from transmitted wave signal arriving prior to the guided wave

One-Sided Nondestructive Evaluation of Back-Side Wedge By Using Ultrasonic Sound (초음파를 이용한 배면웨지의 일방향 비파괴 특성평가)

  • Jeong, Jong-An;Hsu, David K.;Im, Kwang-Hee
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.20 no.6
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    • pp.773-777
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    • 2011
  • Conventional ultrasonic thickness measurement is to be considered as the assumption that the ultrasonic velocity is known. In actual applications the velocity is often not well known and access is often limited to one side. This paper aims at determining the ultrasonic velocity and thickness of plates with parallel or wedged surfaces using contact measurements made on one surface only. For wedged plates the thickness at one point and the wedge angle are determined. Equations are used for determining the ultrasonic velocity, thickness and wedge angle of the plate based on the times-of-flight measured by two contact transducers coupled to one surface. The time-of-flight of the obliquely reflected longitudinal wave echo was measured as a function of the separation between the two transducers. In addition, a simulation was made for comparing the experimental data and a FEM image. Experiments and simulations were performed on flat and wedged plates of aluminium materials; the calculated results for the unknown quantities are generally agreed with them to some degree.

Development of Evaluation Method of External Tendon Force by Using the Deriving Ultrasonic Pulse (유도초음파를 이용한 외부 강선의 긴장력 평가기법 개발)

  • Park, Seung-Bum;Hong, Sung-Su;Yoo, Sung-Won
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.6
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    • pp.181-192
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    • 2007
  • In domestic case, there are no results of corresponding researches for measuring external tendon force. The purpose of the present paper is therefore to measure external tendon force by using deriving ultrasonic method. For this purpose, we designed and manufactured wedges and test system, and measured ultrasonic pulse velocity and pulse amplitude. By using measured data, we tried to analyze the characteristics of tendon force, and to derive the relationship between tendon force and ultrasonic pulse velocity, finally to develop the technic of measuring system using ultrasonic pulse velocity. So tendon force-velocity relationship was proposed by equations, and those equations of which errors were 3.92~8.77% will be possible to adapt in-site.

Non-destruction and Neutralization Properties of Mortar Mixed with Non-active Hwangto and Stone Dust (비활성 황토와 석분을 혼입한 모르타르의 비파괴 및 중성화 특성)

  • 성찬용;윤준노
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.3
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    • pp.59-64
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    • 2003
  • Hwangto would be an environment-friendly material that can be readily used. The purpose of this study is to obtain the absorption ratio, ultrasonic pulse velocity and neutralization of the mortar with non-active Hwangto and stone dust. The absorption ratio and neutralization depth are increased with increase of non-active Hwangto. But, the ultrasonic pulse velocity is decreased with increase of non-active Hwangto. In results of SEM analysis, the crystals are increased with increase of non-active Hwangto.

Influence of Local Ultrasonic Forcing on a Turbulent Boundary layer (국소적 초음파 가진이 난류경계층에 미치는 영향)

  • Park, Young-Soo;Sung, Hyung-Jin
    • 한국가시화정보학회:학술대회논문집
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    • pp.17-22
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    • 2005
  • An experimental study was carried out to investigate the effect of local ultrasonic forcing on a turbulent boundary layer. Stereoscopic particle image velocimetry (SPIV) was used to probe the characteristics of the flow. A ultrasonic forcing system was made by adhering six ultrasonic transducers to the local flat plate. Cavitation which generates uncountable minute air-bubbles having fast wall normal velocity occurs when ultrasonic was projected into water. The SPIV results showed that the wall normal mean velocity is increased in a boundary layer dramatically and the streamwise mean velocity is reduced. The skin friction coefficient ($C_{f}$) decreases $60\%$ and gradually recovers at the downstream. The ultrasonic forcing reduces wall-region streamwise turbulent intensity, however, streamwise turbulent intensity is increased away from the wall. Wall-normal turbulent intensity is almost the same near the wall but it increases away from the wall, In tile vicinity of the wall, Reynold shear stress, sweep strength and production of turbulent kinetic energy were decreased. This suggests that the streamwise vortical structures are lifted by ultrasonic forcing and then skin friction is reduced.

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Influence of Local Ultrasonic Forcing on a Turbulent Boundary Layer (국소적 초음파 가진이 난류경계층에 미치는 영향)

  • Park Young Soo;Sung Hyung Jin
    • Journal of the Korean Society of Visualization
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    • v.3 no.1
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    • pp.78-89
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    • 2005
  • An experimental study was carried out to investigate the effect of local ultrasonic forcing on a turbulent boundary layer. Stereoscopic particle image velocimetry (SPIV) was used to probe the characteristics of the flow. A ultrasonic forcing system was made by adhering six ultrasonic transducers to the local flat plate. Cavitation which generates uncountable minute air-bubbles having fast wall normal velocity occurs when ultrasonic was projected into water. The SPIV results showed that the wall normal mean velocity is increased in a boundary layer dramatically and the streamwise mean velocity is reduced. The skin friction coefficient (C$_{f}$) decreases 60$\%$and gradually recovers at the downstream. The ultrasonic forcing reduces wall-region streamwise turbulent intensity, however, streamwise turbulent intensity is increased away from the wall. Wall-normal turbulent intensity is almost the same near the wall but it increases away from the wall. In the vicinity of the wall, Reynold shear stress, sweep strength and production of turbulent kinetic energy were decreased. This suggests that the streamwise vortical structures are lifted by ultrasonic forcing and then skin friction is reduced.

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Crack Depth Evaluation of Concrete Structures using Ultrasonic Pulse Velocity method (초음파 속도법을 이용한 콘크리트 구조물의 균열깊이 측정)

  • 오병환;김광수;김세훈
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.659-662
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    • 1999
  • Ultrasonic pulse velocity method is employed for evaluation of crack depth in concrete structures. Due to the heterogeneous nature of concrete and the indirect transmission arrangement for the transit time measurement through the surface-opening cracks in concrete structures, ultrasonic pulse velocity has so many variations as crack depths and transmission lengths vary. In this study, ultrasonic pulse velocity method is investigated to evaluate the surface-opening crack depth of concrete slabs, reinforced concrete slabs, reinforced concrete flexural members. the resent study gives a modified method for deminishing errors in transit time measurements and show limitations to the evaluation of crack depth in reinforced concrete structures.

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An Efficient Ultrasonic SAFT Imaging for Pulse-Echo Immersion Testing

  • Hu, Hongwei;Jeong, Hyunjo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.37 no.2
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    • pp.84-90
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    • 2017
  • An ultrasonic synthetic aperture focusing technique (SAFT) using a root mean square (RMS) velocity model is proposed for pulse-echo immersion testing to improve the computational efficiency. Considering the immersion ultrasonic testing of a steel block as an example, three kinds of imaging were studied (B-Scan, SAFT imaging based on ray tracing technology and RMS velocity). The experimental results show that two kinds of SAFT imaging have almost the same imaging performance, while the efficiency of RMS velocity SAFT imaging is almost 25 times greater than the SAFT based on Snell's law.