Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Nondestructive Testing
Journal Basic Information
Journal DOI :
The Korean Society for Nondestructive Testing
Editor in Chief :
Volume & Issues
Volume 28, Issue 6 - Dec 2008
Volume 28, Issue 5 - Oct 2008
Volume 28, Issue 4 - Aug 2008
Volume 28, Issue 3 - Jun 2008
Volume 28, Issue 2 - Apr 2008
Volume 28, Issue 1 - Feb 2008
Selecting the target year
Real-Time Implementation of Medical Ultrasound Strain Imaging System
Jeong, Mok-Kun ; Kwon, Sung-Jae ; Bae, Moo-Ho ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 101~111
Strain imaging in a medical ultrasound imaging system can differentiate the cancer or tumor in a lesion that is stiffer than the surrounding tissue. In this paper, a strain imaging technique using quasistatic compression is implemented that estimates the displacement between pre- and postcompression ultrasound echoes and obtains strain by differentiating it in the spatial direction. Displacements are computed from the phase difference of complex baseband signals obtained using their autocorrelation, and errors associated with converting the phase difference into time or distance are compensated for by taking into the center frequency variation. Also, to reduce the effect of operator's hand motion, the displacements of all scanlines are normalized with the result that satisfactory strain image quality has been obtained. These techniques have been incorporated into implementing a medical ultrasound strain imaging system that operates in real time.
Study on the Dependence of Ultrasonic Phase Velocity on Porosity, Frequency and Propagation Angle in Cancellous Bone
Lee, Kang-Il ; Kim, Yong-Tae ; Choi, Min-Joo ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 112~118
In the present study, the dependence of ultrasonic phase velocity on porosity and frequency in cancellous bone was predicted using the Biot model and the modified Biot-Attenborough (MBA) model for propagation in fluid-saturated porous media. It was also compared with previously published measurements in human and bovine cancellous bones in vitro. It was shown that the phase velocity in cancellous bone decreased with increasing porosity and frequency The dependence of phase velocity on propagation angle in cancellous bone as predicted using the Schoenberg model together with the Biot model and tile MBA model which were modified to include the effect of angle. The theoretical models used in the present study advance our understanding of the interaction between ultrasound and cancellous bone and can be expected to be usefully employed for the diagnosis of osteoporosis.
Modeling of THz Frequency Spectrum via Optical Rectification in THz Time Domain Spectroscopy
Lee, Kang-Hee ; Yi, Min-Woo ; Ahn, Jea-Wook ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 119~124
In recent years, gradually increasing interest has been directed to the use of terahertz technology in nondestructive testing and non-invasive measurements, and terahertz time domain spectroscopy (THz-TDS) has become a key technology in such applications. This paper deals with the terahertz pulse generation from cadmium telluride via optical rectification process of femto-second infrared laser pulses. The measured terahertz spectrum is compared with the result of model calculation based on space-time domain nonlinear Maxwell equations for coherent frequency mixing process. The propagation process of terahertz and infra-red pulses in the material as well as the surface interference and free space diffraction effects are also considered. The experimental results are in good agreements with the calculated spectrum.
Stress Distribution around Laser-Welded Cutting Wheels Using a Spherical Indentation
Lee, Yun-Hee ; Lee, Wan-Kyu ; Jeong, In-Hyeon ; Nahm, Seung-Hoon ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 125~130
A spherical indentation has been proposed as a nondestructive method of measuring local residual stress field in laser-voided joints. The apparent yield strengths interpreted from the spherical indentation data of as-welded cutting wheel were compared with the intrinsic yield strengths measured at nearly equivalent locations in annealed wheel. Their difference along the distance from the welding line is welding stress distribution because the intrinsic yield strength is invariant regardless of the elastic residual stress. The spherical indentations show that the laser-welded diamond cutting wheel displays a 10 min-wide distribution of the welding residual stress and has peak compressive and tensile stresses in the shank and tip regions, respectively.
Position Control of Micro Particles in a Fluid Flow Using Ultrasonic Standing Wave
Cho, Seung-Hyun ; Seo, Dae-Cheol ; Ahn, Bong-Young ; Kim, Ki-Bok ; Kim, Yong-Il ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 131~136
Using ultrasonic standing waves, micro particles submerged or flowing in fluid can be manipulated. Due to acoustic radiation force of ultrasound, particles are forced to move to pressure nodal or antinodal lines. In this work, we propose a method to control the position of micro particle in a flow by adjusting the frequency of the standing wave. To this end, standing wave field generation system including a few millimeter thick micro channel was established using an immersible ultrasonic transducer. The present generation system works valid in a frequency range between 2.0 MHz and 2.5 MHz. We observed the SiC particles in water moved to pressure nodal lines by the standing wave. The effect of the channel thickness and operating frequency was also investigated. Interestingly, it was shown that the operating frequency have a close relation with the location of the pressure nodal line. Consequently, it fan be said that the position of particle movement rail be controlled by adjusting the ultrasound frequency. The maximum range of the controllable position was about 261 micrometers under the given condition. The resulted observations reveal the possibility of various applications of the ultrasonic standing wave to the manipulation of particles submerged in a fluid.
Thermal Deformation Measurement Spherical Glasses Lens Using ESPI
Kim, Koung-Suk ; Jang, Ho-Sub ; Kim, Hyun-Min ; Yang, Seung-Pill ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 137~143
The spherical glasses lenses are typically classified into two groups such as (+) diopter lens and (-) diopter lens by the refractive power index. The thermal deformation of a lens is occurred by external heat source and is changed respected to the diopter of a lens. In this paper, the thermal deformation of spherical glasses lenses were quantitatively measured by using ESPI (electronic speckle pattern interferometry) which has an advantage that the non-contact, non-destructive and precise deformation measurement is available due to the coherency characteristic. The temperature changes were measured by IR camera. It makes experiments over 14 types of the plastic glasses lenses. From the results, it was confirmed that the larger diopter lens showed the less thermal deformation in case of the (+) diopter lens. On the other hand, the thermal deformation of the (-) diopter lens was measured with uniform pattern when the same temperature changes were applied. Also, it was found that the thermnal deformation of the (+) diopter lens is less than that of the (-) diopter lens. Therefore, it is expected that when the thermal deformation is occurred to the various types of the lens, the variation of the focal length caused by the thermal distortion of a lens would be measured quantitatively.
Analysis of Impact Acoustic Property of Apple Using Piezo-Polymer Film Sensor
Kim, Man-Soo ; Lee, Sang-Dae ; Park, Jeong-Hak ; Kim, Ki-Bok ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 144~150
In this study, the PVDF (polyvinylidene fluoride) piero-film sensor was applied to measure the internal quality of apple. The developed sensor detected the response signal through apple after mechanical impact on the surface of apple. The acoustical parameters at time domain such as rise time (RT), ring down count (RC), energy (EN), event duration (ED) and peak amplitude (PA) and acoustical parameter at frequency domain such as spectral density (SE) were analyzed. The size of waveform decreased as storage time of apple increased. The frequency at maximum magnitude was shifted to lower frequency band according to the storage time. The acoustical parameters showed strong relationship with storage time. The multiple linear regression equation was developed to estimate storage time of apple using the acoustical parameters at time domain and its coefficient of determination was 0.97. The internal quality of apple according to storage time is predictable using developed PVDF sensor and acoustical parameters defined in this study.
Development of Comparative Calibration System for Helium Leak Standard by Using Mass Spectrometer Type Leak Detector
Hong, Seung-Soo ; Lim, In-Tae ; Kim, Jin-Tae ; Shin, Yong-Hyeon ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 151~156
Many kinds of mass spectrometer type leak detectors have been widely used for detecting leak of vacuum processes in semiconductor and display industries etc. The leak detectors should be often calibrated by the permeation type standard leak in order to ensure accurate and reproducible leak measurement. We have developed a comparative calibration system for permeation type standard leak by using mass spectrometer type leak detector and specification of the calibration method. Following this technique the reliable calibration for leak standard ran be performed even in fields.
Moire-Fringe-Based Fiber Optic Tiltmeter for Structural Health Monitoring
Kim, Dae-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 157~163
This paper presents a novel fiber optic tiltmeter system for the health monitoring of large-size structures. The system is composed of a sensor head, a light control unit and a signal processing unit. The sensing mechanism of the sensor head is based on a novel integration of the moire fringe phenomenon with fiber optics to achieve a robust performance in addition to its immunity to EM interference, easy ratting, and low cost. In this paper, a prototype of the fiber optic tiltmeter system has been developed successfully. A low-cost light control unit has been developed to drive the system's optic and electronic components. From an experimental test, the fiber optic tiltmeter is proven to be a prospective sensor for the monitoring of the tilting angle of civil structure with a good linearity. Finally, the test also successfully demonstrates the performance and the potential of the novel fiber optic tiltmeter system to monitor the health of civil infrastructures.
Application and Improvement of Surface Wave Transmission Technique for Measuring the Crack Depth in Reinforced Concrete Members
Min, Ji-Young ; Kim, Jae-Hong ; Kwak, Hyo-Gyoung ; Yun, Chung-Bang ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 164~176
In order to assess the existing infrastructures, it is required to measure the crack depth of concrete members. This paper considers the surface wave transmission technique to measure the crack depth. In special, we demonstrate the effect of reinforced bar on surface wave propagation and conclude that the surface wave transmission technique has only the minor error by the reinforced bar. In addition, we propose and validate the optimal window size for eliminating various reflection waves from the boundary of members.
Microstructural Characterization for Structural Health Monitoring of Heat-Resisting Rotor Steels
Kim, C.S. ; Byeon, Jae-Won ; Park, Ik-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 177~183
The typical heat-resisting rotor steels such as 2.25CrMo, 9CrMo and 12CrW steel were experimentally studied in order to understand their materials degradation under high temperature and pressure during the long-term service, and then use the basic studies for the structural health monitoring. In order to monitor the materials degradation, it was conducted by the isothermal aging for 2.25CrMo steel, creep-fatigue for 9CrMo steel and creep for 12Cr steel with the incremental step test. The ultrasonic wave properties, electrical resistivity and coercivity were interpreted in relation to microstructural changes at each material and showed strong sensitivity to the specific microstructural evolution.
Development of Profile Technique for Steam Generator Tubes in Nuclear Power Plants Using
Multi-Array Eddy Current Probe
Nam, Min-Woo ; Lee, Hee-Jong ; Kim, Cheol-Gi ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 184~190
Various ECT techniques have been applied basically to assess the integrity of steam generator tithing in nuclear power plant. Among these techniques, the bobbin probe technique is applied generally to examine the volumetric flaws such as a crack-like defect and wear which is generally occurred on steam generator tubing, and additionally MRPC probe is used to examine closely tile top of tubesheet and bending regions due to the high possibility of cracking. Dent and bulge also may be formed on tube during installation process and operation of steam generator, but the dent and bulge indications greater than specific size criteria are recorded on examination report because these indications are not considered as flaw. These indications can be easily detected with bobbin probe and approximately sized with profile bobbin probe, but the size and shape can not be accurately verified. Accordingly, in this study, the
multi-array EC probe was designed to increase the measurement accuracy of the sectional profiling EC testing of tube. As a result, we would like to propose the application of
multi-array EC probe for the measurement of size and shape of profile change on steam generator tube in OPR-1000 nuclear power plant.
Verification of the Viability of Equipotential Switching Direct Current Potential Drop Method for Piping Wall Loss Monitoring with Signal Sensitivity Analysis
Ryu, Kyung-Ha ; Hwang, Il-Soon ; Kim, Ji-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 191~198
Flow accelerated corrosion (FAC) phenomenon of low alloy carbon steels in nuclear power plant has been known as one of major degradation mechanisms. It has a potential to cause nuclear pipe rupture accident which may directly impact on the plant reliability and safety. Recently, the equipotential switching direct current potential drop (ES-DCPD) method has been developed, by the present authors, as a method to monitor wall loss in a piping. This method can rapidly monitor the thinning of piping, utilizing either the wide range monitoring (WiRM) or the narrow range monitoring (NaRM) technique. WiRM is a method to monitor wide range of straight piping, whereas NaRM focuses significantly on a narrow range such as an elbow. WiRM and NaRM can improve the reliability of the current FAC screening method that is based on computer modeling on fluid flow conditions. In this paper, the measurements by ES-DCPD are performed with signal sensitivity analyses in the laboratory environment for extended period and showed the viability of ES-DCPD for real plant applications.
Finite Element Modeling of Wall Thinning Defects: Applications to Lamb Wave Generation and Interaction
Jeong, Hyun-Jo ; Kim, Tae-Ho ; Lee, Seung-Seok ; Kim, Young-Gil ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 199~204
The generation of axisymmetric Lamb waves and interaction with wall thinning (corrosion) defects in hollow cylinders are simulated using the finite element method. Guided wave interaction with defects in cylinders is challenged by the multi-mode dispersion and the mode conversion. In this paper, two longitudinal, axisymmetric modes are generated using the concept of a time-delay periodic ring arrays (TDPRA), which makes use of the constructive/destructive interference concept to achieve the unidirectional emission and reception of guided waves. The axisymmetric scattering by the wall thinning extending in full circumference of a cylinder is studied with a two-dimensional FE simulation. The effect of wall thinning depth, axial extension, and the edge shape on the reflections of guided waves is discussed.
Magnetic Property Effects of the Strip on Transducer Sensitivity in a Magnetostrictive Strip Type Guided Wave Transducer
Kim, Sung-Joon ; Choi, Myoung-Seon ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 205~210
Magnetic hysteresis loops of a nickel strip and a Fe-Co alloy strip, which have been used in magnetostrictive strip type guided wave transducers for long range ultrasonic testing of pipelines, were measured and then magnetic property effects of a strip on transducer sensitivity were analyzed. The sensitivity of an optimized Fe-Co strip transducer was superior to that of the nickel strip transducer by a factor of about 30. It was shown that this was mainly attributed to the differences in remanence magnetization and coercivity of the two magnetostrictive materials.
A Study on Elastic Guided Wave Modal Characteristics in Multi-Layered Structures
Cho, Youn-Ho ; Lee, Chong-Myoung ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 211~216
In this study, we have developed a program which can calculate phase and group velocities, attenuation and wave structures of each mode in multi-layered plates. The wave structures of each mode are obtained, varying material properties and number of layers. The key in the success of guided wave NDE is how to optimize the mode selection scheme by minimizing energy loss when a structure is in contact with liquid. In this study, the normalized out-of-plane displacements at the surface of a free plate are used to predict the variation of modal attenuation and verily the correlation between attenuation and wave structure. It turns out that the guided wave attenuation can be efficiently obtain from the out-of-plane displacement variation of a free wave guide alleviating such mathematical difficulties in extracting complex roots for the eigenvalue problem of a liquid loaded wave guide. Through this study, the concert to optimize guided wave mode selection is accomplished to enhance sensitivity and efficiency in nondestructive evaluation for multi-layered structures.
Design of Load and Strain Measuring Equipment Using Strain Gage, Instrumental Differential Amplifier and A/D Converter in a Truss System
Baek, Tae-Hyun ; Lee, Byung-Hee ;
Journal of the Korean Society for Nondestructive Testing, volume 28, issue 2, 2008, Pages 217~224
Trusses are found in many common structures such as bridges and buildings. The truss is a fundamental design element in engineering structures and it is important for an engineer to apply the truss design to engineering structures by understanding the mechanics of truss element. In an experimental course, the experiment selves as an example of the usefulness of the Wheatstone bridge in amplifying the output of a transducer. With the apparatus described here, it is possible to obtain experimental measurements of forces in a truss member which agree within errors to predictions from elementary mechanics. The apparatus is inexpensive, easy to operate, and suitable as either a classroom demonstration or student laboratory experiment. This device is a small table-top experiment. The conventional strain measuring device is costly and complicated - it is not simple to understand its structure. Hence, strain gage and the A/D converter are assembled to come up with a load and a strain measuring device. The device was tested for measuring the strain in a loaded specimen and the results were compared to those predicted by theory of mechanics.