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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
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Volume & Issues
Volume 22, Issue 6 - Dec 2002
Volume 22, Issue 5 - Oct 2002
Volume 22, Issue 4 - Aug 2002
Volume 22, Issue 3 - Jun 2002
Volume 22, Issue 2 - Apr 2002
Volume 22, Issue 1 - Feb 2002
Selecting the target year
Nondestructive Advanced Indentation Technique: The Application Study Industrial Structure to Nanomaterial
Jeon, Eun-Chae ; Kwon, Dong-Il ; Choi, Yeol ; Jang, Jae-Il ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 333~346
The continuous indentation techniques are one of the most effective methods to nondestructively estimate mechanical properties. There are many applications in various dimensions of materials from macro-scale, through micro-scale, even to nano-scale range. The macro-range technology of kgf-load level is now focused on the evaluation of tensile properties and residual stress of bulk materials, for example, used in conventional load-bearing structures and in-use pipelines. The technology and the apparatus were successfully developed by a domestic research group. The micro-range technology of gf-load level can be applied to investigate some property-gradient materials such as weldment. Because it has better spatial resolution than the macro-range technology. The nano-range technology (called nanoindentation technique) of mgf-load level is basically used to evaluate hardness and modulus of micro- and nano-materials. Moreover, many researches are going on to measure tensile properties and residual stress. The nanoindentation technology is easy to be applied to the various fields, such as semiconductor devices, multiphase materials, and biomaterials, though other methods are too difficult to be applied due to dimensional or environmental limitations. On the basis of these accomplishments, the international and the domestic standards are being established.
Micromachined pH Sensor Using Open Well Structures
Kim, Heung-Rak ; Kim, Young-Deog ; Jeong, Woo-Cheol ; Kim, Kwang-Il ; Kim, Dong-Su ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 347~353
A structure of a glass electrode-type pH sensor for measuring any concentration of
in an aqueous solution was embodied with bulk micromachining technology. Two open well structures were formed, and a reference electrode was secured by the Ag/AgCl thin film in the sloped side of the etched structure. A sensitive membrane of an indicator electrode for generating a potential by an exchange reaction to
was made with a glass containing Na 20% or more finely so that its thickness might be
or so, and then it was bonded to one pyramidal structure. A liquid junction for a current path was formed by filling an agar in the anisotropically etched part of the Si wafer, which had a size of
, and then bonded it to the other. After complete fabrication of each part, it was filled with a 2M KCl reference solution and encapsulated the sensor structure with a cold expoxy. The potential value of fabricated pH sensor was about 90mV/pH in the standard pH solutions.
Fabrication of 1-3 Piezo-composites with a "Dice & Fill" Method and Characterization of Their Piezoelectric Properties as a Function of Lateral Spatial Scale
Kim, Young-Deog ; Kim, Kwang-Il ; Jeong, Woo-Cheol ; Kim, Heung-Rak ; Kim, Dong-Su ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 354~360
The piezoelectric composites had many advantages in comparison with conventional piezoelectric ceramics and piezopolymers for ultrasonic transducers used in NDT and in medical ultrasionic imaging. The electromechanical coupling coefficient should be high and the acoustic impedance should be low in these applications. However, the cross-coupling with spurious oscillations caused by laterally running plate waves exhibited complex motions in the surface of piezoelectric composites with coarse lateral spatial scale. The thickness mode electromechanical coupling coefficient of 1-3type of piezoelectric compoistes were 0.36 to 0.64, and the acoustic impedance of them were 9.8 to 22.7 MRayl. The lateral resonance frequency of 1-3 type piezoelectric composites shifted to high frequency region with decreasing lateral spatial scale.
Preprocessing of Transmitted Spectrum Data for Development of a Robust Non-destructive Sugar Prediction Model of Intact Fruits
Noh, Sang-Ha ; Ryu, Dong-Soo ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 361~368
The aim of this study was to investigate the effect of preprocessing the transmitted energy spectrum data on development of a robust model to predict the sugar content in intact apples. The spectrum data were measured from 120 Fuji apple samples conveying at the speed of 2 apples per second. Computer algorithms of preprocessing methods such as MSC, SNV, first derivative, OSC and their combinations were developed and applied to the raw spectrum data set. The results indicated that correlation coefficients between the transmitted energy values at each wavelength and sugar contents of apples were significantly improved by the preprocessing of MSC and SNV in particular as compared with those of no-preprocessing. SEPs of the prediction models showed great difference depending on the preprocessing method of the raw spectrum data, the largest of 1.265%brix and the smallest of 0.507% brix. Such a result means that an appropriate preprocessing method corresponding to the characteristics of the spectrum data set should be found or developed for minimizing the prediction errors. It was observed that MSC and SNV are closely related to prediction accuracy, OSC is to number of PLS factors and the first derivative resulted in decrease of the prediction accuracy. A robust calibration model could be d3eveloped by the combined preprocessing of MSC and OSC, which showed that SEP=0.507%brix, bias=0.0327 and R2=0.8823.
Measurement of Dielectric Properties of Cereal Grains by Nondestructive Microwave Measurement Technique
Kim, Ki-Bok ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 369~376
The dielectric properties of cereal grains such as short-grain rough rice, brown rice and barley with various moisture contents were determined by measuring the attenuation and phase shift of the microwave signal trough the grain samples at 9.5GHz. The microwave free-space transmission measurement system consisted of sample holder, horn antenna and network analyzer. Dielectric constant and loss factor of grain samples increased with moisture content and bulk density and agreed well with previous research results. Moisture density, which is defined as the product of moisture content and bulk density, was proposed as a bulk density and variety compensation factor. The technique for measurement of dielectric properties based on free-space transmission may be useful for other particulate materials.
Medical Application of the Nondestructive Ultrasonic Tests: Diagnosis of Micro Bone Fractures using Ultrasonic C Scan Images
Choi, Min-Joo ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 377~385
Ultrasonic tests employing non-ionizing radiation are preferred in nondestructive examinations since they are safe and simple in use. The same principles of the techniques have been taken as valuable tools in medical area for the diagnoses of diseases, in other words, defects of the human body. The paper overviews the principles of the medical diagnosis based on nondestructive ultrasonic tests, and then evaluates experimentally the clinical potential of C scan images not popular in medicine, for detecting the micro fractures of the cortical bone. In the experiment the micro bone fractures were created on the femurs of porks by loading three point bending forces (2-4kN) with the speed of 1 mm/min. As the extent of the fracture was altered, not only X ray images but also ultrasonic C scan images using a focused ultrasonic probe resonated at 25 MHz were obtained. The results showed that ultrasonic C scan images were capable of detecting the micro bone fractures which were not possible to identify by conventional X ray images.
Study of Ultrasound Imaging Technique for Diagnosing Osteoporosis
Kim, H.J. ; Han, S.M. ; Lee, J.H. ; Lee, M.R. ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 386~392
Ultrasonic has been proposed as an attractive means of detecting bone loss. There have been several commercial ultrasound devices developed for measuring the heel to predict fracture at other bones. However, these devices select only single point of heel bone as measurement site. It causes poor assessment of bone quality due to the error of transducer positioning. In an effort to improve current ultrasound systems, we evaluated the linear scanning method which provides better prediction of bone quality and an accurate image of bone shape. The system used in this study biaxially scans a heel bone using automated linear scanning technique. The results demonstrated that the values of ultrasound parameters varied with different positions within bone specimen. It has been also found that the linear scanning method could better pre야ct bone quality, eliminating the error of transducer positioning.
A Study on Measurement of Internal Defects of Pressure Vessel by Digital Shearography(I)
Kang, Young-June ; Park, Nak-Kyu ; Ryu, Won-Jae ; Kim, Kyung-Suk ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 393~401
Pipelines in power plants, nuclear facilities and chemical industries are often affected by corrosion effects. It is important to inspect the internal defects in pipelines in oder to guarantee safe operational condition. We have taken relatively much time, cost and manpower to use conventional NDT methods because these methods are contact measuring methods. In this paper, we used digital shearography, a laser-based optical method which allows full-field measurement of surface displacement derivatives. This method has many advantages in practical use, such as low sensitivity to environmental noise, simple optical configuration and real time measurement. The experiment was performed with pressure vessels which has different internal cracks and detected internal cracks in the pressure vessels at a real time using phase shifting method.
A Study on Measurement of Internal Defects of Pressure Vessel by Digital Shearography(II)
Kang, Young-June ; Park, Nak-Kyu ; Ryu, Won-Jae ; Kim, Dong-Woo ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 402~410
Recently the necessity of study on optical measuring method using laser to detect the pipeline's defect in nuclear facilities, chemical industries and power plants has been increased. Because laser light can be delivered to a remote area without any difficulties, the application of laser in many industries can solve several difficulties from the limitation of access in danger area and reduce the risks of workers. Therefore, we applied a new experimental technique to the measurement of internal defects in pressure vessels with the combination of shearography and image processing technique and detected the internal cracks of pressure vessels in the former paper. In this paper, we used the same optical system as in the former study and found the optimum shearing magnitude by comparing the real length of specimen with experimental results. A variety of conditions were applied to certify the validity of this method. Actually, several specimens which have different lengths and depths were used in this experiment under the three diverse pressure. Consequently, we have carried out this experiment to determine the limit of measurement ability with analyzing errors.
Finite Element Analysis of Ultrasonic Wave Propagation and Scattering
Jeong, Hyun-Jo ; Park, Moon-Cheol ; Park, Yun-Won ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 411~421
The accurate analysis of ultrasonic wave propagation and scattering plays an important role in many aspects of nondestructive evaluation. A numerical analysis makes it possible to perform parametric studies, and in this way the probability of detection and reliability of test results can be improved. In this study, a finite element method was developed for the analysis of ultrasonic fields, the accuracy of results was checked by solving several representative problems. The size of element and the integral time step, which are the critical components for the convergence of numerical results, were determined in a commercial finite element code. Several propagation and scattering problems in 2-D isotropic and anisotropic materials were solved and their results were compared with known analytical or experimental results.
Identification of Flaw Signals Using Deconvolution in Angle Beam Ultrasonic Testing of Welded Joints
Song, Sung-Jin ; Kim, Jun-Young ; Kim, Young-H. ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 4, 2002, Pages 422~429
The identification of ultrasonic flaw signals is a truly difficult task in the angle beam testing of welded joints due to non-relevant signals from the geometric reflectors such as weld roots and counter bores. This paper describes a new approach called "technique for identification of flaw signal using deconvolution(TIFD)" in order to identify the flaw signals in such a problematic situation. The concept of similarity function based on the deconvolution is introduced in the proposed approach. The "reference" signals from both flaws and geometric reflectors and test signals are acquired and normalized. The similarity functions are obtained by deconvolution of test signals with reference signals. The flaw signals could be identified by the patterns of similarity function. The initiative results show great potential of TIFD to distinguish notch comer signals from the geometric reflections.