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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 32, Issue 6 - Dec 2012
Volume 32, Issue 5 - Oct 2012
Volume 32, Issue 4 - Aug 2012
Volume 32, Issue 3 - Jun 2012
Volume 32, Issue 2 - Apr 2012
Volume 32, Issue 1 - Feb 2012
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Numerical Verification of B-WIM System Using Reaction Force Signals
Chang, Sung-Jin ; Kim, Nam-Sik ;
Journal of the Korean Society for Nondestructive Testing, volume 32, issue 6, 2012, Pages 637~647
DOI : 10.7779/JKSNT.2012.32.6.637
Bridges are ones of fundamental facilities for roads which become social overhead capital facilities and they are designed to get safety in their life cycles. However as time passes, bridge can be damaged by changes of external force and traffic environments. Therefore, a bridge should be repaired and maintained for extending its life cycle. The working load on a bridge is one of the most important factors for safety, it should be calculated accurately. The most important load among working loads is live load by a vehicle. Thus, the travel characteristics and weight of vehicle can be useful for bridge maintenance if they were estimated with high reliability. In this study, a B-WIM system in which the bridge is used for a scale have been developed for measuring the vehicle loads without the vehicle stop. The vehicle loads can be estimated by the developed B-WIM system with the reaction responses from the supporting points. The algorithm of developed B-WIM system have been verified by numerical analysis.
Bridge Health Monitoring with Consideration of Environmental Effects
Kim, Yuhee ; Kim, Hyunsoo ; Shin, Soobong ; Park, Jong-Chil ;
Journal of the Korean Society for Nondestructive Testing, volume 32, issue 6, 2012, Pages 648~660
DOI : 10.7779/JKSNT.2012.32.6.648
Reliable response measurements are extremely important for proper bridge health monitoring but incomplete and unreliable data may be acquired due to sensor problems and environmental effects. In the case of a sensor malfunction, parts of the measured data can be missing so that the structural health condition cannot be monitored reliably. This means that the dynamic characteristics of natural frequencies can change as if the structure is damaged due to environmental effects, such as temperature variations. To overcome these problems, this paper proposes a systematic procedure of data analysis to recover missing data and eliminate the environmental effects from the measured data. It also proposes a health index calculated statistically using revised data to evaluate the health condition of a bridge. The proposed method was examined using numerically simulated data with a truss structure and then applied to a set of field data measured from a cable-stayed bridge.
Design of a Bimorph Piezoelectric Energy Harvester for Railway Monitoring
Li, Jingcheng ; Jang, Shinae ; Tang, Jiong ;
Journal of the Korean Society for Nondestructive Testing, volume 32, issue 6, 2012, Pages 661~668
DOI : 10.7779/JKSNT.2012.32.6.661
Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from
base excitation compared to stand-alone piezoelectric energy harvester without tip mass.
Vibration-Based Monitoring of Stay-Cable Force Using Wireless Piezoelectric-Based Strain Sensor Nodes
Nguyen, Khac-Duy ; Kim, Jeong-Tae ;
Journal of the Korean Society for Nondestructive Testing, volume 32, issue 6, 2012, Pages 669~677
DOI : 10.7779/JKSNT.2012.32.6.669
This study presents a method to monitor cable force using wireless sensor nodes and piezoelectric sensors. The following approaches are carried out to achieve the objective. Firstly, the principle of piezoelectric materials (e.g., PZT) as strain sensors is reviewed. A cable force estimation method using dynamic features of cables measured by piezoelectric materials is presented. Secondly, the design of an automated cable force monitoring system using the data acquisition sensor-node Imote2/SHM-DAQ is described. The sensor node is originally developed by University of Illinois at Urbana-Champaign and is adopted in this study to monitor strain-induced voltage from PZT sensors. The advantages of the system are cheap, and eligible for wireless communication and automated operation. Finally, the feasibility of the proposed monitoring system is evaluated on a lab-scaled cable.
Structural Damage Monitoring of Harbor Caissons with Interlocking Condition
Huynh, Thanh-Canh ; Lee, So-Young ; Nguyen, Khac-Duy ; Kim, Jeong-Tae ;
Journal of the Korean Society for Nondestructive Testing, volume 32, issue 6, 2012, Pages 678~685
DOI : 10.7779/JKSNT.2012.32.6.678
The objective of this study is to monitor the health status of harbor caissons which have potential foundation damage. To obtain the objective, the following approaches are performed. Firstly, a structural damage monitoring(SDM) method is designed for interlocked multiple-caisson structures. The SDM method utilizes the change in modal strain energy to monitor the foundation damage in a target caisson unit. Secondly, a finite element model of a caisson system which consists of three caisson units is established to verify the feasibility of the proposed method. In the finite element simulation, the caisson units are constrained each other by shear-key connections. The health status of the caisson system against various levels of foundation damage is monitored by measuring relative modal displacements between the adjacent caissons.
Noncontact Fatigue Crack Evaluation Using Thermoelastic Images
Kim, Ji-Min ; An, Yun-Kyu ; Sohn, Hoon ;
Journal of the Korean Society for Nondestructive Testing, volume 32, issue 6, 2012, Pages 686~695
DOI : 10.7779/JKSNT.2012.32.6.686
This paper proposes a noncontact thermography technique for fatigue crack evaluation under a cyclic tensile loading. The proposed technique identifies and localizes an invisible fatigue crack without scanning, thus making it possible to instantaneously evaluate an incipient fatigue crack. Based on a thermoelastic theory, a new fatigue crack evaluation algorithm is proposed for the fatigue crack-tip localization. The performance of the proposed algorithm is experimentally validated. To achieve this, the cyclic tensile loading is applied to a dog-bone shape aluminum specimen using a universal testing machine, and the corresponding thermal responses induced by thermoelastic effects are captured by an infrared camera. The test results confirm that the fatigue crack is well identified and localized by comparing with its microscopic images.
Rail Inspection Using Noncontact Laser Ultrasonics
Kim, Nak-Hyeon ; Sohn, Hoon ; Han, Soon-Woo ;
Journal of the Korean Society for Nondestructive Testing, volume 32, issue 6, 2012, Pages 696~702
DOI : 10.7779/JKSNT.2012.32.6.696
In this study, a noncontact laser ultrasonic system is proposed for rail defect detection. An Nd-Yag pulse laser is used for generation of ultrasonic waves, and the corresponding ultrasonic responses are measured by a laser Doppler vibrometer. For the detection of rail surface damages, the shape of the excitation laser beam is transformed into a line. On the other hand, a point source laser beam is used for the inspection of defects inside a rail head. Then, the interactions of propagating ultrasonic waves with defects are examined using actual rail specimens. Amplitude attenuation was mainly observed for a surface crack, and reflections were most noticeable from an internal damage. Finally, opportunities and challenges associated with real-time rail inspection from a high-speed train are discussed.
Impact Localization for a Composite Plate Using the Spatial Focusing Properties of Advanced Signal Processing Techniques
Jeong, Hyunjo ; Cho, Sungjong ;
Journal of the Korean Society for Nondestructive Testing, volume 32, issue 6, 2012, Pages 703~710
DOI : 10.7779/JKSNT.2012.32.6.703
A structural health monitoring technique for locating impact position in a composite plate is presented in this paper. The method employs a single sensor and spatial focusing properties of time reversal(TR) and inverse filtering(IF). We first examine the spatial focusing efficiency of both approaches at the impact position and its surroundings through impact experiments. The imaging results of impact localization show that the impact location can be accurately estimated in any position of the plate. Compared to existing techniques for locating impact or acoustic emission source, the proposed method has the benefits of using a single sensor and not requiring knowledge of anisotropic material properties and geometry of structures. Furthermore, it does not depend on a particular mode of dispersive Lamb waves that is frequently used in other ultrasonic testing of plate-like structures.
Corrosion Diagnosis in Bottom Plate of Above Storage Tanks Using Acoustic Emission Techniques
Jung, Hee Jun ;
Journal of the Korean Society for Nondestructive Testing, volume 32, issue 6, 2012, Pages 711~716
DOI : 10.7779/JKSNT.2012.32.6.711