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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
Selecting the target year
Development of On-line Sorting System for Detection of Infected Seed Potatoes Using Visible Near-Infrared Transmittance Spectral Technique
Kim, Dae Yong ; Mo, Changyeun ; Kang, Jun-Soon ; Cho, Byoung-Kwan ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 1~11
DOI : 10.7779/JKSNT.2015.35.1.1
In this study, an online seed potato sorting system using a visible and near infrared (40 1100 nm) transmittance spectral technique and statistical model was evaluated for the nondestructive determination of infected and sound seed potatoes. Seed potatoes that had been artificially infected with Pectobacterium atrosepticum, which is known to cause a soil borne disease infection, were prepared for the experiments. After acquiring transmittance spectra from sound and infected seed potatoes, a determination algorithm for detecting infected seed potatoes was developed using the partial least square discriminant analysis method. The coefficient of determination(
) of the prediction model was 0.943, and the classification accuracy was above 99% (n
Thermal Resolution Analysis of Lock-in Infrared Microscope
Kim, Ghiseok ; Lee, Kye-Sung ; Kim, Geon-Hee ; Hur, Hwan ; Kim, Dong-Ik ; Chang, Ki Soo ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 12~17
DOI : 10.7779/JKSNT.2015.35.1.12
In this study, we analyzed and showed the enhanced thermal resolution of a lock-in infrared thermography system by employing a blackbody system and micro-register sample. The noise level or thermal resolution of an infrared camera system is usually expressed by a noise equivalent temperature difference (NETD), which is the mean square of the deviation of the different values measured for one pixel from its mean values obtained in successive measurements. However, for lock-in thermography, a more convenient quantity in the phase-independent temperature modulation amplitude can be acquired. On the basis of results, it was observed that the NETD or thermal resolution of the lock-in thermography system was significantly enhanced, which we consider to have been caused by the averaging and filtering effects of the lock-in technique.
Data Analysis of Inertial Sensors for Train Positioning Detection System
Kim, Seong Jin ; Park, Sungsoo ; Lee, Jae-Ho ; Kang, Donghoon ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 18~24
DOI : 10.7779/JKSNT.2015.35.1.18
Train positioning detection information is fundamental for high-speed railroad inspection, making it possible to simultaneously determine the status and evaluate the integrity of railroad equipment. This paper presents the results of measurements and an analysis of an inertial measurement unit (IMU) used as a positioning detection sensors. Acceleration and angular rate measurements from the IMU were analyzed in the amplitude and frequency domains, with a discussion on vibration and train motions. Using these results and GPS information, the positioning detection of a Korean tilting train express was performed from Naju station to Illo station on the Honam-line. The results of a synchronized analysis of sensor measurements and train motion can help in the design of a train location detection system and improve the positioning detection performance.
Quantitative Defects Detection in Wind Turbine Blade Using Optical Infrared Thermography
Kwon, Koo-Ahn ; Choi, Man-Yong ; Park, Hee-Sang ; Park, Jeong-Hak ; Huh, Yong-Hak ; Choi, Won Jae ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 25~30
DOI : 10.7779/JKSNT.2015.35.1.25
A wind turbine blade is an important component in wind-power generation, and is generally exposed to harsh environmental conditions. Ultrasonic inspection is mainly used to inspect such blades, but it has been difficult to quantify defect sizes in complicated composite structures. Recently, active infrared thermography has been widely studied for inspecting composite structures, in which thermal energy is applied to an object, and an infrared camera detects the energy emitted from it. In this paper, a calibration method for active optical lock-in thermography is proposed to quantify the size. Inclusion, debonding and wrinkle defects, created in a wind blade for 100 kW wind power generation, were all successfully detected using this method. In particular, a
debonding defect was sized with 98.0% accuracy.
Analysis on Signal Properties due to Concurrent Leaks at Two Points in Water Supply Pipelines
Lee, Young-Sup ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 31~38
DOI : 10.7779/JKSNT.2015.35.1.31
Intelligent leak detection is an essential component of a underground water supply pipeline network such as a smart water grid system. In this network, numerous leak detection sensors are needed to cover all of the pipelines in a specific area installed at specific regular distances. It is also necessary to determine the existence of any leaks and estimate its location within a short time after it occurs. In this study, the leak signal properties and feasibility of leak location detection were investigated when concurrent leaks occurred at two points in a pipeline. The straight distance between the two leak sensors in the 100A sized cast-iron pipeline was 315.6 m, and their signals were measured with one leak and two concurrent leaks. Each leak location was described after analyzing the frequency properties and cross-correlation of the measured signals.
Sensor System for Multi-Point Monitoring Using Bending Loss of Single Mode Optical Fiber
Kim, Heon-Young ; Kim, Dae-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 39~45
DOI : 10.7779/JKSNT.2015.35.1.39
Applications of smart sensors have been extended to safety systems in the aerospace, transportation and civil engineering fields. In particular, structural health monitoring techniques using smart sensors have gradually become necessary and have been developed to prevent dangers to human life and damage to assets. Generally, smart sensors are based on electro-magnets and have several weaknesses, including electro-magnetic interference and distortion. Therefore, fiber optic sensors are an outstanding alternative to overcome the weaknesses of electro-magnetic sensors. However, they require expensive devices and complex systems. This paper proposes a new, affordable and simple sensor system that uses a single fiber to monitor pressures at multiple-points. Moreover, a prototype of the sensor system was manufactured and tested for a feasibility study. Based on the results of this experimental test, a relationship was carefully observed between the bend loss conditions and light-intensity. As a result, it was shown that impacts at multiple-points could be monitored.
Evaluation of Weld Defects in Stainless Steel 316L Pipe Using Guided Wave
Lee, Jin-Kyung ; Lee, Joon-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 46~51
DOI : 10.7779/JKSNT.2015.35.1.46
Stainless steel is a popular structural materials for liquid-hydrogen storage containers and piping components for transporting high-temperature fluids because of its superior material properties such as high strength and high corrosion resistance at elevated temperatures. In general, tungsten inert gas (TIG) arc welding is used for bonding stainless steel. However, it is often reported that the thermal fatigue cracks or initial defects in stainless steel after welding decreases the reliability of the material. The objective of this paper is to clarify the characteristics of ultrasonic guided wave propagation in relation to a change in the initial crack length in the welding zone of stainless steel. For this purpose, three specimens with different artificial defects of 5 mm, 10 mm, and 20 mm in stainless steel welds were prepared. By considering the thickness of s stainless steel pipe, special attention was given to both the L(0,1) mode and L(0,2) mode in this study. It was clearly found that the L(0,2) mode was more sensitive to defects than the L(0,1) mode. Based on the results of the L(0,1) and L(0,2) mode analyses, the magnitude ratio of the two modes was more effective than studying each mode when evaluating defects near the welded zone of stainless steel because of its linear relationship with the length of the artificial defect.
Feasibility Study of Flexible Phased Array Ultrasonic Technology Using Irregular Surface Specimen
Lee, Seung-Pyo ; Moon, Yong-Sig ; Jung, Nam-Du ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 52~60
DOI : 10.7779/JKSNT.2015.35.1.52
Nuclear power plant contain many dissimilar metal welds that connect carbon steel components with stainless steel pipes using alloy600 welding materials. Primary water stress corrosion cracks at dissimilar metal welds have been continuously reported around the world. In periodic integrity evaluations, dissimilar metal welds are examined using a generic ultrasonic testing procedure, KPD-UT-10. In this procedure, the gap between the probe and examination surface is limited to 1/32 inch (0.8mm). It is not easy to test some dissimilar metal welds in Korean plants applying ordinary technology because of their tapered shapes and irregular surface conditions. This paper introduces a method for applying a flexible phased array technology to improve the reliability of ultrasonic testing results for various shapes and surface conditions. The artificial flaws in specimens with irregular surfaces were completely detected using the flexible phased array ultrasonic technology. Therefore, it can be said that the technology is applicable to field examination.
Evaluation of Nondestructive Evaluation Size Measurement for Integrity Assessment of Axial Outside Diameter Stress Corrosion Cracking in Steam Generator Tubes
Joo, Kyung-Mun ; Hong, Jun-Hee ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 61~67
DOI : 10.7779/JKSNT.2015.35.1.61
Recently, the initiation of outside diameter stress corrosion cracking (ODSCC) at the tube support plate region of domestic steam generators (SG) with Alloy600 HTMA tubes has been increasing. As a result, SGs with Alloy600 HTMA tubes must be replaced early or are scheduled to be replaced prior to their designed lifetime. ODSCC is one of the biggest threats to the integrity of SG tubes. Therefore, the accurate evaluation of tube integrity to determine ODSCC is needed. Eddy current testing (ECT) is conducted periodically, and its results could be input as parameters for evaluating the integrity of SG tubes. The reliability of an ECT inspection system depends on the performance of the inspection technique and abilty of the analyst. The detection probability and ECT sizing error of degradation are considered to be the performance indices of a nondestructive evaluation (NDE) system. This paper introduces an optimized evaluation method for ECT, as well as the sizing error, including the analyst performance. This study was based on the results of a round robin program in which 10 inspection analysts from 5 different companies participated. The analysis of ECT sizing results was performed using a linear regression model relating the true defect size data to the measured ECT size data.
Shape-Estimation of Human Hand Using Polymer Flex Sensor and Study of Its Application to Control Robot Arm
Lee, Jin-Hyuk ; Kim, Dae-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 35, issue 1, 2015, Pages 68~72
DOI : 10.7779/JKSNT.2015.35.1.68
Ultrasonic inspection robot systems have been widely researched and developed for the real-time monitoring of structures such as power plants. However, an inspection robot that is operated in a simple pattern has limitations in its application to various structures in a plant facility because of the diverse and complicated shapes of the inspection objects. Therefore, accurate control of the robot is required to inspect complicated objects with high-precision results. This paper presents the idea that the shape and movement information of an ultrasonic inspector`s hand could be profitably utilized for the accurate control of robot. In this study, a polymer flex sensor was applied to monitor the shape of a human hand. This application was designed to intuitively control an ultrasonic inspection robot. The movement and shape of the hand were estimated by applying multiple sensors. Moreover, it was successfully shown that a test robot could be intuitively controlled based on the shape of a human hand estimated using polymer flex sensors.