• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.8
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• pp.559-567
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• 2015

The paper deals with an ultrasonic transducer invented for measuring both flow velocity and pipe thickness. The structure of the transducer is based on the conventional transducers for measuring flow velocity by obliquely transmitting ultrasonic waves to the flow direction. The transducer additionally generates ultrasonic waves transmitting vertically to a pipe for measuring pipe thickness. By measuring flow velocity with the invented transducer and a conventional oblique-incidence transducer and comparing their results, the accuracy of the flow velocity measurement of the invented one was evaluated. By measuring specimen thickness with the invented transducer and a conventional normal-incidence transducer and comparing their results, the accuracy of the thickness measurement of the invented one was evaluated.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.851-856
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• 2003

This paper proposes a single-mode Lamb-wave generation and detection system using a pulsed laser as a generator and an air-coupled transducer combined with the wavelet transform analysis, as the detector. The laser source with arrayed linear slits was used to generate Lamb-wave which is able to control the wavelength of Lamb-wave to be generated by changing the slits separation. An ari-coupled transducer was used to receive Lamb-wave, which can selectably receive a single mode of leaky Lamb wave by changing the oblique angle of transducer, since the leaky Lamb-wave has unique leaky-angle according to the mode. Also, the received signal was processed by wavelet transform for the analysis in domain of time-frequency. The theoretical dipersion curve and the experimetal result was compared to show good agreement.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.342-348
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• 2006

A new magnetostrictive patch array transducer for the generation and detection of torsional waves is developed fur the on-line health monitoring of rotating shafts. Even though the torsional wave is useful in nondestructive evaluation due to its non-dispersive property, a transducer generating torsional waves in rotating shafts has not been developed so far. In this research, a torsional wave transducer using the magnetostrictive effect is newly developed. By bonding an away of magnetostrictive rectangular patches on the outer surface of the shaft at an oblique angle of $45^{\circ}$ and encircling the array by a solenoid coil, we have successfully generated and measured torsional waves by the developed transducer. Several experiments were carried out to check the transducer performance.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.45-54
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• 1999

Non destructive test is applied to revise mechanical strength and assume material strength or defect of material, equipment and structure, instead of fracture test. Especially, ultrasonic test has the characteristics such as an excellent permeability high-sensitiveness to fine defect and an almost exact measurement for position, size and direction of inner defect which differ from other non destructive tests. In this study, the program is developed to evaluate optimal testing condition, to distinguish obstacle echo and defect position. This program on the basic of Ray-Tracing model shows generation and processing of ultrasonic pulse. The simulation is compared with testing in the 3 cases of an oblique angle transducer like $45^{\circ},\;60^{\circ}\;and\;70^{\circ}$. The test result for all conditions is well compared with simulation result when relative not is within $0.1{\sim}7.2%$. And the course of several echos is simply assumed through simulation.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.95-103
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• 1994

The purpose of this paper is to provide the experimenters who use the oblique incidence ultrasonic method for anisotropic elastic constants measurement eith some useful relations. In particular, the equivalence of the times of flight by the energy ad phase velocities, which is key to the oblique incidence method, is proved explicitly. This equivalence greatly simplifies the analysis of immersion measurement results. In oredr to correctly measure the transit time of an immersed sample using the oblique incidence, the receiving transducer should be shifted laterally, and an expression in given for this shift. A method for determining all nine elastic constants of an orthotropic material is briefly described and the measurement results are listed for SiC particulate reinforced A1 matrix composites.

• Physical Therapy Korea
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• v.19 no.3
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• pp.1-10
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• 2012

The aim of this study is to compare measurements of abdominal muscle thickness using ultrasonography imaging (USI) to those using a special transducer head device, during five different trunk stabilization exercises, ultimately to determine which exercise led to the greatest muscle thickness. Thirty eight healthy subjects participated in this cross-sectional study. The five types of trunk stabilization - i.e., a sit-up on the supine, an upper and lower extremity raise with quadruped on the prone, a leg raise in sitting on the ball, trunk rolling on the ball, and balance using sling on the prone position - were each performed with an abdominal draw. The thickness of the abdominal muscle - including the transverse abdominal (TrA), internal oblique (IO), and external oblique (EO) - was measured by USI with a special transducer head device, at rest and then at contraction in each position. Data were analyzed using one-way repeated ANOVA with the level of significance set at ${\alpha}$=.05. The results were as follows: 1) the TrA thickness was statistically significant (p<.05), whereas the IO and EO thicknesses were not (p>.05); 2) among the five types of trunk stabilization, TrA thickness significantly increased with the balance using a sling in the prone position, (p<.05), whereas no significant difference was noted for the four types of trunk stabilization (p>.05); 3) reliability data showed that there was a high degree of consistency among the measurements taken using the special transducer head device (ICC=.92). In conclusion, the balance using a sling in the prone position was more effective than any of the four other types of trunk stabilization in increasing TrA thickness in healthy subjects.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.37-44
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• 2001

Ultrasonic testing has a characteristics such as excellent permeability, high-sensitivity to find defect and an almost exact measurement for position. size and direction of inner defect, which differ from other non-destructive testing. In the study, we developed program into optimal testing condition, to distinguish obstacle echo and defect position. This program shows generation and processing of ultrasonic pulse. We compared simulation with ultrasonic test in 45$^\circ$, 60$^\circ$and 70$^\circ$transducer. Test results were in accordance with simulation within 0.1~7.2%.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.3
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• pp.153-161
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• 2006

A simulation program SIMULTSONIC is under development at CNDE to help determine and/or help optimize ultrasonic probe locations for inspection of complex components. SIMULTSONIC provides a ray-trace based assessment for immersion and contact modes of inspection. The code written in Visual C++ operating in Microsoft Windows environment provides an interactive user interface. In this paper, a description of the various features of SIMULTSONIC is given followed by examples illustrating the capability of SIMULTSONIC to deal with inspection of canonical objects such as pipes. In particular, the use of SIMULTSONIC in the inspection of very thin-walled pipes (with 450 urn wall thickness) is described. Ray trace based assessment was done using SIMULTSONIC to determine the standoff distance and the angle of oblique incidence for an immersion mode focused transducer. A 3-cycle Hanning window pulse was chosen for simulations. Experiments were carried out to validate the simulations. The A-scans and the associated B-Scan images obtained through simulations show good correlation with experimental results, both with the arrival time of the signal as well as with the signal amplitudes.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.3
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• pp.211-219
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• 2014

Closed cracks are difficult to detect using conventional ultrasonic testing because most incident ultrasound passes completely through these cracks. Nonlinear ultrasound inspection using sub-harmonic frequencies a promising method for detecting closed cracks. To implement this method, a sub-harmonic phased array (PA) is proposed to visualize the length of closed cracks in solids. A sub-harmonic PA generally consists of a single transmitter and an array receiver, which detects sub-harmonic waves generated from closed cracks. The PA images are obtained using the total focusing method (TFM), which (with a transmitter and receiving array) employs a full matrix in the observation region to achieve fine image resolution. In particular, the receiving signals are measured using a laser Doppler vibrometer (LDV) to collect PA images for both fundamental and sub-harmonic frequencies. Oblique incidence, which is used to boost sub-harmonic generation, inevitably produces various surface waves that contaminate the signals measured in the receiving transducer. Surface wave interference often degrades PA images severely, and it becomes difficult to read the closed crack's position from the images. Various methods to prevent or eliminate this interference are possible. In particular, enhancing images with signal processing could be a highly cost-effective method. Because periodic patterns distributed in a PA image are the most frequent interference induced by surface waves, spatial frequency filtering is applicable for removing these waves. Experiments clearly demonstrate that the spatial frequency filter improves PA images.

• Journal of Veterinary Clinics
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• v.25 no.2
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• pp.90-95
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• 2008

One fresh equine cadaver (two forelimbs) and five non-lamed thoroughbreds (ten sound forelimbs) were examined ultrasonographically through 5.0 MHz linear array transducer with a stand-off pad in palmar pastern region. The normal transverse ultrasonographic images of the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), straight sesamoidean ligament (SSL), oblique sesamoidean ligament (OSL), and medium scutum could be identified at the region. The mean $\pm$ SD (min.$\sim$max. $mm^2$) of SDFT cross-sectional areas at P1A, P1B, P1C in the region were $110.00{\pm}5.38$ ($100{\sim}128$), $100.00{\pm}5.02$ ($90{\sim}111$), $114.00{\pm}3.33$ ($104{\sim}124$), respectively. The mean $\pm$ SD (min.$\sim$max. $mm^2$) of DDFT cross-sectional areas at each phalanx (P1A, P1B, P1C, P2A, P2B) were $136.00{\pm}4.83$ ($125{\sim}147$), $94.00{\pm}5.43$ ($85{\sim}108$), $99.00{\pm}4.87$ ($90{\sim}111$), $115.00{\pm}3.67$ ($108{\sim}124$), $135.00{\pm}3.65$ ($125{\sim}145$), respectively. The mean ratio of SDFT of P1B to DDFT was 0.74, 1.06, 1.01, 0.87, 0.74 at P1A, P1B, P1C, P2A, P2B, respectively.