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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 24, Issue 6 - Dec 2004
Volume 24, Issue 5 - Oct 2004
Volume 24, Issue 4 - Aug 2004
Volume 24, Issue 3 - Jun 2004
Volume 24, Issue 2 - Apr 2004
Volume 24, Issue 1 - Feb 2004
Selecting the target year
Development of Smart Active Layer Sensor (I) : Theory and Concept Study
Yoon, Dong-Jin ; Lee, Young-Sup ; Kwon, Jae-Hwa ; Lee, Sang-Il ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 5, 2004, Pages 465~475
This paper is the first part of the study on the development of a smart active layer (SAL) sensor, which consists of two parts. In this first part, the theory and concept of the SAL sensor is investigated, which is designed for the detection of elastic waves caused by internal cracks and damages in structures. For the development SAL sensor, (i) the basic theory of elastic waves was studied, (ii) the feasible study of the SAL as an elastic waves detection sensor using the finite element analysis (FEA) with respect to a piezoceramic disc was performed. (iii) the comparison of performances between some piezoceramic sensors and a commercial acoustic emission (AE) sensor was accomplished to ensure the applicability by the experimental means, such as a pencil lead break test. Also, the conceptional study for the SAL sensor, which can be utilized for the effective detection and locating of defects by the arrangement of regularly distributed sensors, was discussed.
Development of Smart Active Layer Sensor (II): Manufacturing and Application
Lee, Young-Sup ; Lee, Sang-Il ; Kwon, Jae-Hwa ; Yoon, Dong-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 5, 2004, Pages 476~486
This paper is the second part of the study on the development of a smart active layer (SAL) sensor, which consists of two parts. As mentioned in the first paper, structural health monitoring (SHM) is a new technology that is being increasingly applied at the industrial field as a potential approach to improve cost and convenience of structural inspection. Recently, the development of smart sensor is very active for real application. This study has focused on preparation and application study of SAL sensor which is described with regard to the theory and concept of the SAL sensor in the first paper. In order to detect elastic wave, smart piezoelectric sensor, SAL, is fabricated by using a piezoelectric element, shielding layer and protection layer. This protection layer plays an important role in a patched network of distributed piezoelectric sensor and shielding treatment. Four types of SAL sensor are designed/prepared/tested, and these details will be discussed in the paper In this study, SAL sensor ran be feasibly applied to perform structural health monitoring and to detect damage sources which result in elastic waves.
Development of Capacitive Micromachined Ultrasonic Transducer (I) - Analysis of the Membrane Behavior
Kim, Ki-Bok ; Ahn, Bong-Young ; Park, Hae-Won ; Kim, Young-Joo ; Lee, Seung-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 5, 2004, Pages 487~493
This study was conducted to develope a capacitive micromachined ultrasonic transducer (cMUT) which enable to high efficient non-contact transmit and receive the ultrasonic wave in air. Theoretical analysis and finite element analysis of the behavior of membrane (such as resonance frequency, membrane deflection, collapse deflection and collapse voltage) of the cMUT were performed. The design parameters of the cMUT such as the dimension and thickness of membrane, thickness of sacrificial layer, thickness and size of electrode were estimated. The resonance frequency of the membrane increased as the thickness of the membrane increased but decreased as the diameter of the membrane increased. The deflection of the membrane increased as d-c bias voltage increased. The collapse voltage of the membrane was analyzed.
Fire Detection of a Building Using Wireless Multi-point Temperature Sensors
Kim, Chi-Yeop ; Kwon, Il-Bum ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 5, 2004, Pages 494~498
Fire accidents often happen in large buildings because large buildings are equipped with heavy electrical wiring and piping. When fire is to be occurred in those buildings, it is very dangerous to People and building structures. Therefore, multi-point wireless temperature sensors for large buildings are necessary in order to detect fire in the early time and thus to minimize the loss. A wireless device was composed of the transmitter and receiver. The specification of this device was as follows: 915MHz of transmitted frequency, 4 channels, 9600bps of the transmitted speed, and 10mW of the transmitted power. We confirmed through experiment that the temperature was well sensed and fire location was determined by the 4 channel sensors of the developed sensor system.
A Study on the Security of Infrastructure using fiber Optic Scattering Sensors
Kwon, Il-Bum ; Yoon, Dong-Jin ; Lee, Seung-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 5, 2004, Pages 499~507
We have studied tile detection techniques, which can determine the location and the weight of an intruder into infrastructure, by using fiber-optic ROTDR (Rayleigh optical time domain reflectometry) sensor and fiber-optic BOTDA (Brillouin Optical time domain analysis) sensor, which can use an optical fiber longer than that of ROTDR sensor Fiber-optic sensing plates of ROTDR sensor, which arc buried in sand, were prepared to respond the intruder effects. The signal of ROTDR was analyzed to confirm the detection performance. The constructed ROTDR could be used up to 10km at the pulse width of 30ns. The location error was less than 2 m and the weight could be detected as 4 grades, such as 20kgf, 40kgf, 60kgf and 80kgf. Also, fiber optic BOTDA sensor was developed to be able to detect intrusion effect through an optical fiber of tells of kilometers longer than ROTDR sensor. fiber-optic BOTDA sensor was constructed with 1 laser diode and 2 electro-optic modulators. The intrusion detection experiment was peformed by the strain inducing set-up installed on an optical table to simulate all intrusion effect. In the result of this experiment, the intrusion effort was well detected as the distance resolution of 3m through the fiber length of about 4.81km during 1.5 seconds.
The Study of Near-field Scanning Microwave Microscope for the Nondestructive Detection System
Kim, Joo-Young ; Kim, Song-Hui ; Yoo, Hyun-Jun ; Yang, Jong-Il ; Yoo, Hyung-Keun ; Yu, Kyong-Son ; Kim, Seung-Wan ; Lee, Kie-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 5, 2004, Pages 508~517
We described a near-field scanning microwave microscope which uses a high-quality dielectric resonator with a tunable screw. The operating frequency is f=4.5 5GHz. The probe tip is mounted in a cylindrical resonant cavity coupled to a dielectric resonator We developed a hybrid tip combining a reduced length of the tapered part with a small apex. In order to understand the function of the probe, we fabricated three different tips using a conventional chemical etching technique and observed three different NSMM images for patterened Cr films on glass substrates. We measured the reflection coefficient of different metal thin film samples with the same thickness of 300m and compared with theoretical impedance respectly. By tuning the tunable screw coming through the top cover, we could improve sensitivity, signal-to-noise ratio, and spatial resolution to better than
. To demonstrate the ability of local microwave characterization, the surface resistance of metallic thin films has been mapped.
Evaluation of the Thermal Degradation in Co-based Superalloy using High frequency Transducer of Scanning Acoustic Microscope
Park, Ik-Keun ; Cho, Dong-Su ; Kim, Yong-Kwon ; Lim, Jae-Seang ; Kim, Chung-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 5, 2004, Pages 518~524
The feasibility of Y(z) curve method of scanning acoustic microscope using high frequency transducer was experimentally studied for assessment of the thermal degradation in Co-based superalloy. Thermal degradation was performed to simulate the microstructural changes in Co-based superalloy arising from long term exposure at high temperature. Longitudinal wave velocity measured by pulse echo method using 10MHz transducer and leaky surface acoustic wave (LSAW) velocity measured by V(z) curve method using 200MHE transducer were measured to investigate the effect on thermal degradation. Ultrasonic velocity decreased as the aging time increased in both ultrasonic waves. Moreover, the low frequency longitudinal wave velocity decreased a little. Otherwise, the high frequency LSAW velocity drastically decreased up to a maximum of 4.7% at the aging time of 4,000hours. A good correlation was found between LSAW and Vickers hardness. Consequently, V(z) curve method of SAM using high frequency transducer could be a potential tool for assessing thermal degradation.
The Utilization of Nondestructive Testing and Defects Diagnosis using Infrared Thermography
Choi, Man-Yong ; Kim, Won-Tae ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 5, 2004, Pages 525~531
In this paper, the concept of infrared thermography(IRT), the principle of measurement of IRT and how to set up the IR camera for the nondestructive testing are described in detail. Also, its utilization and non-destructive testing(NDT) diagnosis are reviewed. By performing the periodic non-touched WDT through the estimation of thermal patterns related with the temperature for the surface targeted, IRT can be applied to the early prevention of the device failure. For the diagnosis utilization, thermal imaging patterns obtained from IRT for heated blocks with internal defects were estimated through the lion-destructive method and discussed the way of IRT estimation from the analysis of characteristics between material defects and thermal imaging patterns.
The Evaluation of Surface Crack in Paramagnetic Material by FEF Technique
Kim, Hoon ;
Journal of the Korean Society for Nondestructive Testing, volume 24, issue 5, 2004, Pages 532~537
FEF(Focused Electromagnetic Field) technique was newly developed that is based on the induction principle exciting electromagnetic field. The technique consists of an induction wire and a sensor for detecting electromagnetic field, and is applied in a non-contact mode. In this study, the technique was applied to the evaluation of EDM slits in some conductive materials - aluminum alloy, stainless steel and Inconel alloy. The voltage in the non-defect region is depended upon the measurement lift-off. The voltage signals on defects are measured with peak values, and the peak values changed with the depth of defects. The voltage distributions for all conductive materials are the same trend.