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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 30, Issue 6 - Dec 2010
Volume 30, Issue 5 - Oct 2010
Volume 30, Issue 4 - Aug 2010
Volume 30, Issue 3 - Jun 2010
Volume 30, Issue 2 - Apr 2010
Volume 30, Issue 1 - Feb 2010
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Self-Sensing of Single Carbon Fiber/Carbon Nanotube-Epoxy Composites Using Electro-Micromechanical Techniques and Acoustic Emission
Park, Joung-Man ; Jang, Jung-Hoon ; Wang, Zuo-Jia ; Kwon, Dong-Jun ; Park, Jong-Kyu ; Lee, Woo-Il ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 411~422
Self-sensing on micro-failure, dispersion degree and relating properties, of carbon nanotube(CNT)/epoxy composites, were investigated using wettability, electro-micromechanical technique with acoustic emission(AE). Specimens were prepared from neat epoxy as well as composites with untreated and acid-treated CNT. Degree of dispersion was evaluated comparatively by measuring volumetric electrical resistivity and its standard deviation. Apparent modulus containing the stress transfer was higher for acid-treated CNT composite than for the untreated case. Applied cyclic loading responded well for a single carbon fiber/CNT-epoxy composite by the change in contact resistivity. The interfacial shear strength between a single carbon fiber and CNT-epoxy, determined in a fiber pullout test, was lower than that between a single carbon fiber and neat epoxy. Regarding on micro-damage sensing using electrical resistivity measurement with AE, the stepwise increment in electrical resistivity was observed for a single carbon fiber/CNT -epoxy composite. On the other hand, electrical resistivity increased infinitely right after the first carbon fiber breaks for a single carbon fiber/neat epoxy composite. The occurrence of AE events of added CNT composites was much higher than the neat epoxy case, due to micro failure at the interfaces by added CNTs.
Out-of-Plane Deformation Measurement of TPS in Vehicle Using ESPI
Han, Sang-Kil ; Ham, Hyo-Shick ; Ham, Sang-Hyun ; Lee, Jong-Hwang ; Jung, Won-Wook ; Lee, Chang-Hee ; Lee, Sang-Bong ; Choi, Sung-Eul ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 423~428
In this paper, we analyzed the characteristics of thermal deformation of the TPS which is a core part of engine in vehicle by measuring out-of-plane deformation using ESP!. Inspection area of a test piece was minimized to 5 cm by 5 cm by using a high resolution CCD and a zoom lens. 4-step phase shifting method was used along with phase unwrapping algorithm to get a continuous phase map, configurations and deformations were displayed as 3D images. When heating the test pieces while maintaining the temperature at about
, the out-of-plane deformations were measured. The results showed that a test piece with longer distance traveled tends to show larger thermal deformation, we could observes a convex shaped deformation on the surface. The inner defect sample, we could monitor discontinuous pattern phase map, and a concave shaped deformation on the surface.
Evaluation and Application of T-Ray Nondestructive Characterization of FRP Composite Materials
Im, Kwang-Hee ; Hsu, David K. ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 429~436
Recently, (terahertz ray) applications have emerged as one of the most promising new powerful nondestructive evaluation (NDE) techniques. In this study, a new T-ray time-domain spectroscopy system was utilized for detecting and evaluating layup effect and flaw in FRP composite laminates. Extensive experimental measurements in reflection and thru-transmission modes were made to map out the T-ray images. Especially this was demonstrated in thick GFRP laminates containing double saw slots. In carbon composites the penetration of terahertz waves is limited to some degree and the detection of flaws is strongly affected by the angle between the electric field(E-field) vector of the terahertz waves and the intervening fiber directions. The artificial defects investigated by terahertz waves were bonded foreign material, simulated disbond and delamination and mechanical impact damage. The effectiveness and limitations of terahertz radiation for the NDE of composites are discussed.
Nondestructive Evaluation of Nanostructured Thin Film System Using Scanning Acoustic Microscopy
Miyasaka, Chiaki ; Park, Ik-Keun ; Park, Tae-Sung ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 437~443
In recent years, as nano scale structured thin film technology has emerged in various fields such as the materials, biomedical and acoustic sciences, the quantitative nondestructive adhesion evaluation of thin film interfaces using ultra high frequency scanning acoustic microscopy(SAM) has become an important issue in terms of the longevity and durability of thin film devices. In this study, an effective technique for investigating the interfaces of nano scale structured thin film systems is described, based on the focusing of ultrasonic waves, the generation of leaky surface acoustic waves(LSAWs), V(z) curve simulation and ultra high frequency acoustical imaging_ Computer simulations of the V(z) curve were performed to estimate the sensitivity of detection of micro flaws(i.e., delamination) in a thin film system. Finally, experiments were conducted to confirm that a SAM system operating at a frequency of 1 GHz can be useful to visualize the micro flaws in nano structured thin film systems.
Evaluation of Microscopic Degradation of Copper and Copper Alloy by Electrical Resistivity Measurement
Kim, Chung-Seok ; Nahm, Seung-Hoon ; Hyun, Chang-Young ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 444~450
In the present study, the microscopic degradation of copper and copper alloy subjected to cyclic deformation has been evaluated by the electrical resistivity measurement using the DC four terminal potential method. The copper (Cu) and copper alloy (Cu-35Zn), whose stacking fault energy is much different each other, were cyclically deformed to investigate the response of the electrical resistivity to different dislocation substructures. Dislocation cell substructure was developed in the Cu, while the planar array of dislocation structure was developed in the Cu-35Zn alloy increasing dislocation density with fatigue cycles. The electrical resistivity increased rapidly in the initial stage of fatigue deformation in both materials. Moreover, after the fatigue test it increased by about 7 % for the Cu and 6.5 % for the Cu-35Zn alloy, respectively. From these consistent results, it may be concluded that the dislocation cell structure responds to the electrical resistivity more sensitively than the planar array dislocation structure evolved during cyclic fatigue.
Ultrasonic Nonlinearity Measurement in Heat Treated SA508 Alloy: Influences of Grains and Precipitates
Baek, Seung-Hyun ; Lee, Tae-Hun ; Kim, Chung-Seok ; Jhang, Kyung-Young ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 451~457
In the present study, the influences of grains and precipitates of microstructural evolution on the ultrasonic nonlinearity have been experimentally investigated. The prior-austenite grain and precipitate size are controlled by the variation in austenitizing and tempering conditions in reactor pressure vessel materials of nuclear power plant, SA508 Gr.3 low alloys. The ultrasonic nonlinearity was found to have strong correlations with grains and precipitates since the ultrasonic nonlinear parameter
shows decrease trend with coarsening of grains and precipitates. Although the prior-austenite grain size increased, the
changed little due to the effects of subgrains, packets and laths. For the preciptate effects, the
decreased sharply due to decrease in
causing the coherency stain in addition to the precipitate size. The results in this study may provide a potential for characterizing the microstructural evolution, grains and precipitates, by measuring the ultrasonic nonlinearity.
Lamb Wave Technique for Ultrasonic Nonlinear Characterization in Elastic Plates
Lee, Tae-Hun ; Kim, Chung-Seok ; Jhang, Kyung-Young ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 458~463
Since the acoustic nonlinearity is sensitive to the minute variation of material properties, the nonlinear ultrasonic technique(NUT) has been considered as a promising method to evaluate the material degradation or fatigue. However, there are certain limitations to apply the conventional NUT using the bulk wave to thin plates. In case of plates, the use of Lamb wave can be considered, however, the propagation characteristics of Lamb wave are completely different with the bulk wave, and thus the separate study for the nonlinearity of Lamb wave is required. For this work, this paper analyzed first the conditions of mode pair suitable for the practical application as well as for the cumulative propagation of quadratic harmonic frequency and summarized the result in for conditions; (1) phase matching, (2) non-zero power flux, (3) group velocity matching, and (4) non-zero out-of-plane displacement. Experimental results in aluminum plates showed that the amplitude of the secondary Lamb wave and nonlinear parameter growed up with increasing propagation distance at the mode pair satisfying the above all conditions and that the ration of nonlinear parameters measured in Al6061-T6 and Al1100-H15 was closed to the ratio of the absolute nonlinear parameters.
Degradation Evaluation of Mechanical Properties for 12Cr Ferrite Heat Resisting Steel by Reversible Permeability
Ryu, Kwon-Sang ; Kim, Min-Gi ; Nahm, Seung-Hoon ; Kim, Chung-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 464~470
The integrity of the industrial equipment in use under high temperature and high pressure must be assessed by regularly measuring the degraded mechanical properties during service time. In order to nondestructively monitor the degraded mechanical properties of industrial equipment, a measuring method of the reversible permeability(RP) using surface type probe is presented. The method for measuring the RP is based on that RP is the differential value of hysteresis loop. The RP is exactly the foundation hatmonics induced in a detecting coil measured by lock-in amplifier tuned to a frequency of the alternating perturbing magnetic field. The peak of RP is measured around the coercive force. Steel material used in this work was 12Cr ferritic heat resisting steel. The eleven kinds of samples aged during different times under same temperature (
) were prepared. Peak interval of reversible permeability(PIRP), Vickers hardness, and tensile strength measured for the aged samples decreased abruptly for short aging time (below 500 h), but the change became small at a long aging time. Vickers hardness and tensile strength linearly decreased as RIRP decreased, so the degraded mechanical properties of 12Cr ferritic heat resisting steel could be nondestructively evaluated by measuring RIRP.
Measurement of Tensile Properties for Thin Aluminium Film by Using White Light Interferometer
Kim, Sang-Kyo ; Oh, Chung-Seog ; Lee, Hak-Joo ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 471~478
Thin films play an important role in many technological applications including microelectronic devices, magnetic storage media, MEMS and surface coatings. It is well known that a thin film's material properties can be very different from the corresponding bulk properties and thus there has been a strong need for the development of a reliable test method to measure the mechanical properties of a thin film. We have developed an alternative and convenient test method to overcome the limitations of previous membrane deflection experiment and uniaxial tensile test by adopting a white light interferometer having sub-nanometer out-of-plane displacement resolution. The freestanding aluminium specimens are tested to verity the effectiveness of the test method developed and get the tensile properties. The specimens are 0.5 rum wide,
thick and fabricated through MEMS processes including sputtering. 1 to 5 specimens are fabricated on Si dies. The membrane deflection experiments are carried out by using a homemade tester consisted of a motor-driven loading tip, a load cell, and 6 DOF alignment stages. The test system is compact enough to set it up beneath a commercial white light interferometric microscope. The white light fringes are utilized to align a specimen with the tester. The Young's modulus and yield point stress of the aluminium film are 62 GPa and 247 MPa, respectively.
Interpretation for Band-Type Indication on Radiography of 9% Ni Steel Welds for LNG Storage Tanks
Lee, Seung-Hyun ; Lee, Seung-Rim ; Lee, Young-Soon ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 479~483
9% nickel alloy steels used for LNG, cryogenic liquid, storage tank are welded with dissimilar Inconel or Hastelloy welding rod and the weldment shows similar characteristic with the dissimilar metal weld of low carbon steel and austenitic stainless steel. Band type indications are sometimes shown on the film during radiography test of the weldments. Thus this study identified whether the indications are non-relevant indications through material, radiographic test, ultrasonic test, liquid penetrant test and microstructure analysis and also proposed radiography film interpretation and cause of band type indications.
A Study on Infrared Emissivity Measurement of Material Surface by Reflection Method
Kang, Byung-Chul ; Kim, Sang-Myoung ; Choi, Joung-Yoon ; Kim, Gun-Ok ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 484~488
Infrared emissivity is one of the most important factors for the temperature measurement by infrared thermography. Although the infrared emissivity of an object can be measured from the ratio of blackbody and the object, at room temperature it is practically difficult to measure the value due to the background effects. Hence, quantitative reflectance of bare steel plate and the surface of coating was measured by FT-IR spectroscopy and emissivity was calculated from this. The emissivity of polished bare steel surface was from 0.06 to 0.10 and the value for the unpolished bare steel can not be achieved because optical characteristics changes of surface roughness induces erroneous results. Emissivity of transparent paint coated steel was from 0.50 to 0.84. Depends on the IR absorption regions, which is a characteristic value of the coating, emissivity changes. This study suggests surface condition of material, thickness, roughness et cetra are important factor for IR optical characteristics. Emissivity measurement by reflection method is useful technique to be applied for metal and it with coating applied on the surface. The range of experimental errors of temperature can be narrowed by the application of infrared thermography from the measured thermal emissivity.
State of the Art in Life Assessment for High Temperature Components Using Replication Method
Kim, Duck-Hee ; Choi, Hyun-Sun ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 489~496
The power generation and chemical industry have been subjected to further material degradation with long term operations and need to predict the remaining service life of components, such as reformer tube and steam turbine rotor, that have operated at elevated temperatures. As a non-destructive technique, replication method with reliable metallurgical life and microstructural soundness assessment has been recognized with strongly useful method until now. Developments of this method have variously accomplished by new quantitative approach, such as carbide analysis, with A-parameter and grain deformation method. An overview of replication, some new techniques for material degradation and life assessment were introduced in this paper. Also, on-site applications and its reasonableness were described. As a result of having analyzed microstructure by replication method, carbide approach was quantitatively useful to life assessment.
Adaptation and Implementation of Predictive Maintenance Technique with Nondestructive Testing for Power Plants
Jung, Gye-Jo ; Jung, Nam-Gun ;
Journal of the Korean Society for Nondestructive Testing, volume 30, issue 5, 2010, Pages 497~502
Many forces are pressuring utilities to reduce operating and maintenance costs without cutting back on reliability or availability. Many utility managers are re-evaluating maintenance strategies to meet these demands. To utilities how to reduce maintenance costs and extent the effective operating life of equipment, predictive maintenance technique can be adapted. Predictive maintenance has three types program which arc in-house program, engineering company program and mixed program. We can approach successful predictive maintenance program with "smart trust" concept.