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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 31, Issue 6 - Dec 2011
Volume 31, Issue 5 - Oct 2011
Volume 31, Issue 4 - Aug 2011
Volume 31, Issue 3 - Jun 2011
Volume 31, Issue 2 - Apr 2011
Volume 31, Issue 1 - Feb 2011
Selecting the target year
Strain Measurement of Steel Roof Truss Using FBG Sensor during Construction of Reverse Shell Shaped Reinforced Concrete Structure
Lee, Kun-Woo ; Rhim, Hong-Chul ; Seo, Tae-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 335~342
Application of FBG (Fiber Bragg Grating) sensors to measure strain of steel roof trusses has been performed. This is to check and confirm the structural integrity of an unusually shaped, reverse shell structure made of reinforced concrete. The issue was to place sensors at proper location and compare the measured values to the results from structural analysis. It has been learned that a deliberate measurement scheme is needed in order to monitor a complex structure during construction. In this study, the measured values were within allowable range of strain, thus confirming the safety of the structure during measurement and construction.
Estimation of Dynamic Characteristics of Existing Dam Floodgate Using Ambient Vibration
Kim, Nam-Gyu ; Lee, Jong-Jae ; Bea, Jung-Ju ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 343~350
Recently, as the catastrophic disasters due to earthquake happen frequently all over the world, it draws lots of attention to seismic capacity evaluation and/or structural integrity assessment of deteriorated civil infra-structures. However, there have been few studies on the existing dam flood gates, expecially in Korea. In this study, a proper vibration testing method applicable to a dam flood gate has been suggested, since the dynamic characteristics of a darn flood gate can be fundamental data for seismic capacity evaluation or structural integrity assessment. The frequency domain decomposition technique has been incorporated for modal parameter identification. Two kinds of vibration tests using an impact hammer and ambient vibration sources were carried out on two types of dam floodgates with different shapes. Through the field tests, the effectiveness of the ambient vibration tests were verified.
Pipeline Structural Damage Detection Using Self-Sensing Technology and PNN-Based Pattern Recognition
Lee, Chang-Gil ; Park, Woong-Ki ; Park, Seung-Hee ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 351~359
In a structure, damage can occur at several scales from micro-cracking to corrosion or loose bolts. This makes the identification of damage difficult with one mode of sensing. Hence, a multi-mode actuated sensing system is proposed based on a self-sensing circuit using a piezoelectric sensor. In the self sensing-based multi-mode actuated sensing, one mode provides a wide frequency-band structural response from the self-sensed impedance measurement and the other mode provides a specific frequency-induced structural wavelet response from the self-sensed guided wave measurement. In this study, an experimental study on the pipeline system is carried out to verify the effectiveness and the robustness of the proposed structural health monitoring approach. Different types of structural damage are artificially inflicted on the pipeline system. To classify the multiple types of structural damage, a supervised learning-based statistical pattern recognition is implemented by composing a two-dimensional space using the damage indices extracted from the impedance and guided wave features. For more systematic damage classification, several control parameters to determine an optimal decision boundary for the supervised learning-based pattern recognition are optimized. Finally, further research issues will be discussed for real-world implementation of the proposed approach.
Elasto-Magnetic Sensor-Based Local Cross-Sectional Damage Detection for Steel Cables
Kim, Ju-Won ; Nam, Min-Jun ; Park, Seung-Hee ; Lee, Jong-Jae ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 360~366
The Elasto-magnetic sensor is applied to detect the local cross-sectional loss of steel cables in this study while it was originally developed for measuring the tensile force in the previous works. To verify the feasibility of the proposed damage detection technique, steel bars which have 4-different diameters were fabricated and the output voltage value was measured at each diameter by the E/M sensor. Optimal input voltage and working point are chosen so that the linearity and resolution of results can ensure through repeated experiments, and then the E/M sensor was measured the output voltage values at the damage points of steel bar specimen that was applied the 4 types of damage condition based on the selected optimal experimental condition. This proposed approach can be an effective tool for steel cable health monitoring.
The Theoretical Investigation of Phased Array Guided Waves
Lee, Jae-Sun ; Cho, Youn-Ho ; Achenbach, Jan D. ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 367~373
Guided waves inspection techniques that are different with inspection technique by bulk waves are widely used in pipe line evaluation due to advantages of long distance inspection. However, most of pipe lines at industrial fields are buried and/or coated. In this case, due to the attenuation effect from soil and/or coating material, there are a lot of difficulty on inspection by conventional ultrasonic technique. In this paper, guided waves propagating patterns are calculated with respect to excitation mode by Normal Mode Expansion(NME). Guided waves patterns based on excited by single transducer and guided wave focusing technique have employed to analyze focusing pattern on a pipe. A longitudinal mode and high order flexural modes are used with various number of transducers to determine sensitivity. Guided waves energy excited by multi transducer with focusing algorithm was successfully focused at a desired point.
Fiber Optic Displacement Sensor System for Structural Health Monitoring
Lee, Kun-Ho ; Ahn, Byung-Jun ; Kim, Dae-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 374~381
It has been doing to research on novel techniques for structural health monitoring by applying various sensor techniques to measure the deflection in mechanical and civil structures. Several electric-based displacement sensors have many difficulties for using them because of EMI (Electro-Magnetic Interference) noise of many lead-wires when they are installed to many points in the structures. In this paper, it is proposed an affordable intensity-based fiber optic sensor to measure small displacement solving the problems of conventional sensors. In detail, the sensor head was designed on the basis of the principle of bending loss and a basic experiment was performed to obtain the sensitivity, the linearity and the stroke of the sensor. Moreover, a prototype was designed and manufactured to be easily installed to a structure and a real-time control software was also successfully developed to drive the fiber optic sensor system.
Feasibility Study on Packaged FBG Sensors for Debonding Monitoring of Composite Wind Turbine Blade
Kwon, Il-Bum ; Choi, Ki-Sun ; Kim, Geun-Jin ; Kim, Dong-Jin ; Huh, Yong-Hak ; Yoon, Dong-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 382~390
Smart sensors embedable in composite wind turbine blades have been required to be researched for monitoring the health status of large wind turbine blades during real-time operation. In this research, the feasibility of packaged FBG sensor probes was studied through the experiments of composite blade trailing edge specimens in order to detect cracking and debonding damages. The instants of cracking and debonding generated in the shear web were confirmed by rapid changes of the wavelength shifts from the bare FBG sensor probes. Packaged FBG sensor probes were proposed to remove the fragile property of bare FBG sensor probes attached on composite wind blade specimens. Strain and temperature sensitivity of fabricated probes installed on the skin of blade specimen were almost equal to those of a bare FBG sensor. Strain sensitivity was measured to be
/pm in a strain range from to 0 to 600
, and the calculated temperature sensitivity was to be 48 pm/
in the heating test up to 80 degree.
Study on the Image Quality Comparison between in Digital RT and Film RT
Park, Sang-Ki ; Ahn, Yean-Shik ; Gil, Doo-Song ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 391~397
Conventional film radiographic test has been generally and widely used in the inspection on the weldment for quality assurance. On the other hand, since the analog RT is well known for typical time and cost consuming method with complex process of inspection, the industry has researched various ways how to improve radiographic test technology. In this study, we verified the fact that digital RT provides a lot more benefit in effectively detecting defects, ever film details, through digital processing of image enhancement, compared to film RT. As a result, we reached conclusion that digital RT is positively able to replace the film RT in industry in part or in whole.
Review of Non-Destructive Evaluation Technologies for Rail Inspection
Han, Soon-Woo ; Cho, Seung-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 398~413
For railway safety, it is very important to detect damages of rails at their early stage because any undetected damage in a rail can break the rail and cause a serious railway accident. In this paper, several NDT applicable to rail inspections are described. Major damage types in rails are discussed first and the rail inspection technology using conventional piezoelectric ultrasonic transducers, which is widely adopted for damage detection of rails, is explained. Other NDT being researched or tested for rail inspection are also discussed as complementary technologies to the concurrent contact type ultrasonic inspection. Characteristics of each rail inspection technologies are evaluated in order to provide requirements for future development of a new rail inspection method.
Piezoelectric Ultrasonic Transducer for NDT
Kim, Gi-Bok ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 414~420
Research Trends in THz Wave (II) - TeraHertz Imaging Technology
Seo, Dae-Cheol ; Kim, Gi-Bok ;
Journal of the Korean Society for Nondestructive Testing, volume 31, issue 4, 2011, Pages 421~424