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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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Design and Array Signal Suggestion of Array Type Pulsed Eddy Current Probe for Health Monitoring of Metal Tubes
Shin, Young Kil ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 5, 2015, Pages 291~298
DOI : 10.7779/JKSNT.2015.35.5.291
An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.
Study on Enhancements to Ultrasonic Data Imaging Using Full Matrix Capture Technique
Lee, Tae-Hun ; Yoon, Byung-Sik ; Lee, Jeong-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 5, 2015, Pages 299~306
DOI : 10.7779/JKSNT.2015.35.5.299
A conventional phased array system can control an ultrasonic beam electronically by adjusting the excitation time delay of individual elements in a multi-element probe and produce an ultrasonic image. In Contrast, full matrix capture (FMC) is a data acquisition process that allows receiving ultrasonic signals from one single shot of the phased array transducer element through all the other elements and captures the complete dataset from every possible transmit-receive combination. This FMC data can be used to create the ultrasonic image in post processing. It is possible to produce not only images equivalent to conventional phased array image but also total focusing method (TFM) images with improved resolution and sharpness, which is virtually focused at any point in a region of interest. In this paper, the system that can perform FMC by using a conventional phased array instrument is developed, and a study was conducted on the imaging algorithms to reconstruct sector B-scan and TFM images from FMC dataset.
Steam Leak Detection Method in a Pipeline Using Histogram Analysis
Kim, Se-Oh ; Jeon, Hyeong-Seop ; Son, Ki-Sung ; Chae, Gyung-Sun ; Park, Jong Won ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 5, 2015, Pages 307~313
DOI : 10.7779/JKSNT.2015.35.5.307
Leak detection in a pipeline usually involves acoustic emission sensors such as contact type sensors. These contact type sensors pose difficulties for installation and cannot operate in areas having high temperature and radiation. Therefore, recently, many researchers have studied the leak detection phenomenon by using a camera. Leak detection by using a camera has the advantages of long distance monitoring and wide area surveillance. However, the conventional leak detection method by using difference images often mistakes the vibration of a structure for a leak. In this paper, we propose a method for steam leakage detection by using the moving average of difference images and histogram analysis. The proposed method can separate the leakage and the vibration of a structure. The working performance of the proposed method is verified by comparing with experimental results.
A Femtosecond Laser Metrology on the Thermal Conductivity of a Nanoscale Superconductor Material
Kim, Yun Young ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 5, 2015, Pages 314~320
DOI : 10.7779/JKSNT.2015.35.5.314
The present study investigates the thermal characteristics of a nanoscale superconductor material. A thin-film of
was deposited on a
substrate by using a pulsed-laser deposition technique and characterized using an ultrafast laser system. In order to extract a thermal conductivity value, a numerical solution for a transient one-dimensional heat conduction equation was obtained using a finite-difference method. The curve-fit shows a value 1.2 W/mK, which is relatively lower than those of bulk materials. This research provides a material property of superconductor thin-film required for the thermal design of micro or nanodevices.
A Study about Detection of Defects in the Nuclear Piping Loop System Using Cooling Lock-in Infrared Thermography
Kim, Sang-Chae ; Kang, Sung-Hoon ; Yun, Na-Yeon ; Jung, Hyun-Chul ; Kim, Kyeong-Suk ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 5, 2015, Pages 321~331
DOI : 10.7779/JKSNT.2015.35.5.321
A study on the application of cooling defect detection was performed on the basis of a preceding study on the heated defect detection in nuclear piping loop system, using lock-in infrared thermography. A loop system with piping defects was made by varying the wall-thinning length, the circumference orientation angle, and the wall-thinning depth. The test was performed using an IR camera and a cooling device. Distance between the cooling device and the target loop system was fixed at 2 m. For analyzing experimental results, the temperature distribution data for cooling, and phase data were obtained. Through the analysis of this data, the defect length was measured. The reliability of the measurements for cooling defect conditions was shown to be higher in the lock-in infrared thermography data than the infrared thermography data.
Energy Based Source Location by Using Acoustic Emission for Damage Detection in Steel and Composite CNG Tank
Kim, Il-Sik ; Han, Byeong-Hee ; Park, Choon-Su ; Yoon, Dong-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 5, 2015, Pages 332~340
DOI : 10.7779/JKSNT.2015.35.5.332
Acoustic emission (AE) is an effective nondestructive test that uses transient elastic wave generated by the rapid release of energy within a material to detect any further growth or expansion of existing defects. Over the past decades, because of environmental issues, the use of compressed natural gas (CNG) as an alternative fuel for vehicles is increasing because of environmental issues. For this reason, the importance and necessity of detecting defects on a CNG fuel tank has also come to the fore. The conventional AE method used for source location is highly affected by the wave speed on the structure, and this creates problems in inspecting a composite CNG fuel tank. Because the speed and dispersion characteristics of the wave are different according to direction of structure and laminated layers. In this study, both the conventional AE method and the energy based contour map method were used for source location. This new method based on pre-acquired D/B was used for overcoming the limitation of damage localization in a composite CNG fuel tank specimen which consists of a steel liner cylinder overwrapped by GFRP. From the experimental results, it is observed that the damage localization is determined with a small error at all tested points by using the energy based contour map method, while there were a number of mis-locations or large errors at many tested points by using the conventional AE method. Therefore, the energy based contour map method used in this work is more suitable technology for inspecting composite structures.
Measurement Uncertainty on Subsurface Defects Detection Using Active Infrared Thermographic Technique
Chung, Yoonjae ; Kim, Wontae ; Choi, Wonjae ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 5, 2015, Pages 341~348
DOI : 10.7779/JKSNT.2015.35.5.341
Active infrared thermography methods have been known to possess good fault detection capabilities for the detection of defects in materials compared to the conventional passive thermal infrared imaging techniques. However, the reliability of the technique has been under scrutiny. This paper proposes the lock-in thermography technique for the detection and estimation of artificial subsurface defect size and depth with uncertainty measurement.
A Study on Impact Monitoring Using a Piezoelectric Paint Sensor
Choi, Kyungwho ; Kang, Donghoon ; Park, Seung-Bok ; Kang, Lae-Hyong ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 5, 2015, Pages 349~357
DOI : 10.7779/JKSNT.2015.35.5.349
The piezoelectric paint sensor is a paint type sensor comprising of an epoxy and piezoelectric powder, which is the main component of a piezoelectric material. This sensor can be easily attached to any type of structure as compared to other sensors because it is viable to directly apply it on structures, as in the case with a typical paint. In this study, the capability of piezoelectric paint sensor for impact detection was evaluated. In Particular, the applications of the piezoelectric paint sensor for railroad vehicles were considered. There have been various cases reported about the damages caused by flying gravel to the under-cover of the railroad vehicle during operation. In order to prevent this, real-time monitoring of the large under-cover surface of the railroad vehicle is unavoidable. Under the assumption of vehicle application, sensor sensitivities were measured after multiple and prolonged exposure to thermal cycle environment
). Sensitivity evaluation of paint sensor under environmental conditions was conducted in an aluminum specimen. In results, despite the small variations in sensitivity, we could confirm the applicability of this paint sensor for impact detection even after a severe environmental exposure test.
A Study on the Nondestructive Test Optimum Design for a Ground Tracked Combat Vehicle
Kim, Byeong Ho ; Seo, Jae Hyun ; Gil, Hyeon Jun ; Kim, Seon Hyeong ; Seo, Sang Chul ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 5, 2015, Pages 358~366
DOI : 10.7779/JKSNT.2015.35.5.358
In this study, a nondestructive test (NDT) is performed to inspect the optimal design of a ground tracked combat vehicle for self-propelled artillery, tank, and armored vehicles. The minimum qualification required for personnel performing the NDT of a ground tracked combat vehicle was initially established in US military standards, and then applied to the Korean defense specifications to develop a ground tracked combat vehicle. However, the qualification standards of an NDT inspector have been integrated into NAS410 through the military and commercial specifications unification project that were applied in the existing aerospace/defense industry public standard. The design method for this study was verified by applying the optimal design to the liquid penetrant testing Al forging used in self-propelled artillery. This confirmed the reliability and soundness of the product.