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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Nondestructive Testing
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Journal DOI :
The Korean Society for Nondestructive Testing
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Volume & Issues
Volume 35, Issue 6 - Dec 2015
Volume 35, Issue 5 - Oct 2015
Volume 35, Issue 4 - Aug 2015
Volume 35, Issue 3 - Jun 2015
Volume 35, Issue 2 - Apr 2015
Volume 35, Issue 1 - Feb 2015
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Influence of Cortical Endplates on Ultrasonic Properties of Trabecular Bone
Kim, Yoon Mi ; Lee, Kang Il ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 2, 2015, Pages 103~111
DOI : 10.7779/JKSNT.2015.35.2.103
The present study investigated the influence of thick cortical endplates on the ultrasonic properties of trabecular bone in a femur with a high fracture risk. Twelve trabecular bone samples were prepared from bovine femurs, and acrylic plates with thicknesses of 1.25, 1.80, and 2.75 mm were manufactured to simulate the cortical endplates using acrylic with a density and a sound speed similar to cortical bone. Although the thickness of the acrylic plates attached to the two sides of the trabecular bone increased, high correlations were observed between the speed of sound and the apparent bone density of the trabecular bone, with Pearson's correlation coefficients of 0.80-0.86. High correlations were also observed between the attenuation coefficient at 0.5 MHz and the apparent bone density of the trabecular bone, with Pearson's correlation coefficients of 0.84-0.91. These results suggest that the speed of sound and attenuation coefficient at a specific frequency measured in a femur with relatively thick cortical endplates compared to the calcaneus could be used as indices for predicting the bone mineral density of the femur.
Signal-Characteristic Analysis with Respect to Backing Material of PVDF-Based High-Frequency Ultrasound for Photoacoustic Microscopy
Lee, Junsu ; Chang, Jin Ho ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 2, 2015, Pages 112~119
DOI : 10.7779/JKSNT.2015.35.2.112
Photoacoustic microscopy is capable of providing high-resolution molecular images, and its spatial resolution is typically determined by ultrasonic transducers used to receive the photoacoustic signals. Therefore, ultrasonic transducers for photoacoustic microscopy (PAM) should have a high operating frequency, broad bandwidth, and high signal-reception efficiency. Polyvinylidene fluoride (PVDF) is a suitable material. To take full advantage of this material, the selection of the backing material is crucial, as it influences the center frequency and bandwidth of the transducer. Therefore, we experimentally determined the most suitable backing material among EPO-TEK 301, E-Solder 3022, and RTV. For this, three PVDF high-frequency single-element transducers were fabricated with each backing material. The center frequency and -6 dB bandwidth of each transducer were ascertained by a pulse-echo test. The spatial resolution of each transducer was examined using wire-target images. The experimental results indicated that EPO-TEK 301 is the most suitable backing material for a PAM transducer. This material provides the highest signal magnitude and a reasonable bandwidth because a large portion of the energy propagates toward the front medium, and the PVDF resonates in the half-wave mode.
Design and Fabrication of Linear-Array Ultrasonic Transducer Using KLM and FEM Simulation for Non-Destructive Testing
Park, Chan-Yuk ; Sung, Jin-Ho ; Jeong, Jong-Seob ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 2, 2015, Pages 120~127
DOI : 10.7779/JKSNT.2015.35.2.120
In this paper, a linear-array transducer capable of overcoming the faults of a single element and phased array transducers with convex shape for non-destructive ultrasonic testing was designed and fabricated. A 5.5 MHz linear-array transducer was designed using the PiezoCAD program based on the KLM analysis and the PZFlex program based on the FEM analysis. A 2-2 composite structure was employed to achieve broad-band characteristics. A 128 element linear-array transducer was fabricated and its performance was compared with the simulation results. The center frequency of the fabricated transducer was 5.5 MHz and the -6 dB frequency bandwidth was 70 %. Thus, we expect that the designed transducer can provide an effective inner image of the test material during non-destructive ultrasonic testing.
Construction of Static 3D Ultrasonography Image by Radiation Beam Tracking Method from 1D Array Probe
Kim, Yong Tae ; Doh, Il ; Ahn, Bongyoung ; Kim, Kwang-Youn ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 2, 2015, Pages 128~133
DOI : 10.7779/JKSNT.2015.35.2.128
This paper describes the construction of a static 3D ultrasonography image by tracking the radiation beam position during the handy operation of a 1D array probe to enable point-of-care use. The theoretical model of the transformation from the translational and rotational information of the sensor mounted on the probe to the reference Cartesian coordinate system was given. The signal amplification and serial communication interface module was made using a commercially available sensor. A test phantom was also made using silicone putty in a donut shape. During the movement of the hand-held probe, B-mode movie and sensor signals were recorded. B-mode images were periodically selected from the movie, and the gray levels of the pixels for each image were converted to the gray levels of 3D voxels. 3D and 2D images of arbitrary cross-section of the B-mode type were also constructed from the voxel data, and agreed well with the shape of the test phantom.
Study of Focusing Characteristics of Ultrasound for Designing Acoustic Lens in Ultrasonic Moxibustion Device
Bae, Jae-Hyun ; Song, Sung-Jin ; Kim, Hak-Joon ; Kim, Ki-Bok ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 2, 2015, Pages 134~140
DOI : 10.7779/JKSNT.2015.35.2.134
Traditional moxibustion therapy can cause severe pain and leave scarring burns at the moxibustion site as it relies on the practitioner's subjective and qualitative treatment. Recently, ultrasound therapy has received attention as an alternative to moxibustion therapy owing to its objectiveness and quantitative nature. However, in order to convert ultrasound energy into heat energy, there is a need to precisely understand the ultrasound-focusing characteristics of the acoustic lens. Therefore, in this study, an FEM simulation was performed for acoustic lenses with different geometries a concave lens and zone lens as the geometry critically influences ultrasound focusing. The acoustic pressure field, amplitude, and focal point were also calculated. Furthermore, the performance of the fabricated acoustic lens was verified by a sound pressure measurement experiment.
Damage Measurement for Molybdenum Thin Film Using Reflection-Type Digital Holography
Kim, Kyeong-Suk ; Jung, Hyun-Il ; Shin, Ju-Yeop ; Ma, Hye-Joon ; Kwon, Ik-Hwan ; Yang, Seung-Pill ; Hong, Chung-Ki ; Jung, Hyun-Chul ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 2, 2015, Pages 141~149
DOI : 10.7779/JKSNT.2015.35.2.141
In the fabrication of electronic circuits used in electronic products, molybdenum thin films are deposited on semiconductors to prevent oxidation. During the deposition, the presence of a particle or dust at the interface between the thin film and substrate causes the decrease of adhesion, performance, and life cycle. In this study, a damage measurement targeting two kinds of glass substrate, with and without particles, was performed in order to measure the change in the molybdenum thin film deposition area in the presence of a particle. Clean and dirty molybdenum thin film specimens were fabricated and directly deposited on a substrate using the sputtering method, and a reflection-type digital holographic interferometer was configured for measuring the damage. Reflection-type digital holography has several advantages; e.g., the configuration of the interferometer is simple, the measurement range can be varied depending on the magnification of a microscopic lens, and the measuring time is short. The results confirm that reflection-type digital holography is useful for the measurement of the damage and defects of thin films.
Analysis of Factors Influencing Fire Damage to Concrete Using Nonlinear Resonance Vibration Method
Park, Gang-Kyu ; Park, Sun-Jong ; Yim, Hong Jae ; Kwak, Hyo-Gyoung ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 2, 2015, Pages 150~156
DOI : 10.7779/JKSNT.2015.35.2.150
In this study, the effects of different mix proportions and fire scenarios (exposure temperatures and post-fire-curing periods) on fire-damaged concrete were analyzed using a nonlinear resonance vibration method based on nonlinear acoustics. The hysteretic nonlinearity parameter was obtained, which can sensitively reflect the damage level of fire-damaged concrete. In addition, a splitting tensile strength test was performed on each fire-damaged specimen to evaluate the residual property. Using the results, a prediction model for estimating the residual strength of fire-damaged concrete was proposed on the basis of the correlation between the hysteretic nonlinearity parameter and the ratio of splitting tensile strength.