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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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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
Reduction of Radiographic Quantum Noise Using Adaptive Weighted Median Filter
Lee, Hoo-Min ; Nam, Moon-Hyon ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 465~473
Images are easily corrupted by noise during the data transmission, data capture and data processing. A technical method of noise analyzing and adaptive filtering for reducing of quantum noise in radiography is presented. By adjusting the characteristics of the filter according to local statistics around each pixel of the image as moving windowing, it is possible to suppress noise sufficiently while preserve edge and other significant information required in reading. We have proposed adaptive weighted median(AWM) filters based on local statistics. We show two ways of realizing the AWM filters. One is a simple type of AWM filter, whose weights are given by a simple non-linear function of three local characteristics. The other is the AWM filter which is constructed by homogeneous factor(HF). Homogeneous factor(HF) from the quantum noise models that enables the filter to recognize the local structures of the image is introduced, and an algorithm for determining the HF fitted to the detection systems with various inner statistical properties is proposed. We show by the experimented that the performances of proposed method is superior to these of other filters and models in preserving small details and suppressing the noise at homogeneous region. The proposed algorithms were implemented by visual C++ language on a IBM-PC Pentium 550 for testing purposes, the effects and results of the noise filtering were proposed by comparing with images of the other existing filtering methods.
Development of Radiometric Scanning System for the Evaluation of the Pipeline
Kim, Yong-Kyun ; Hong, Seok-Boong ; Chung, Chong-Eun ; Lee, Yoon-Ho ; Jung, Yong-Ha ; Lee, Jeong-Ki ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 474~482
One dimensional Radiometric scanning system was fabricated and tested as a filmless radiographic inspection system, which could be applied to the evaluation of the corrosion and deposits in the pipeline. This system is composed of the single radioactive source of the collimated focusing beam, and single scintillation detector of BGO, and the mechanical scanning system to transport and align the source and detector, and the operating software to automatically control the mechanical scan system. The performance of the system was simulated using GEANT4 software. This system is applied to one specimen having an artificial falw(flat bottom hole) in the pipe and the other specimen with thickness variation. For the inspection by using the radioactive source in the pipeline, it is possible to evaluate the corrosion and deposits in real time and without film.
Thickness Evaluation of Pipeline Using Density Profile on a Radiograph
Lee, Sung-Sik ; Jang, Byoung-Gyu ; Kim, Young-H. ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 483~489
The computer simulation has been done for non-insulated and insulated pipes which are vacant or half filled with liquid. The simulation results showed that the density profile on the radiography is continuous and symmetrical around the center of pipe in the case of vacant pipe. On the other hand the density profiles are not symmetrical and depend on geometrical setting for radiography in the case of half filled pipes. Finally, experimental testing on a non-insulated carbon steel pipe with artificial notches of different depth is carried out using Ir-192 and industrial film. Comparing the measured density profile on the radiograph to the calculated one, it has been shown that it is possible to evaluate thickness variation by measuring density profile on a radiograph.
Development of Automatic Remote Exposure Controller for Gamma Radiography
Joo, Gwang-Tae ; Shin, Jin-Seong ; Kim, Dong-Eun ; Song, Jung-Ho ; Choo, Seung-Hwan ; Chang, Hong-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 490~499
Recently, gamma radiographic equipments have been used about 1,000 sets manually and operated by about 2,500 persons in Korea. In order for a radiography to work effectively with avoiding any hazard of the high level radiation from the source, many field workers have expected developing a wireless automatic remote exposure controller. The KlTCO research team has developed an automatic remote exposure controller that can regulate the speed of
by BLDC motor of 24V 200W which has output of
, suitable torque and safety factor for the work. And the developed automatic remote exposure controller can control rpm of motor, pigtail position by photo-sensor and exposure time by timer to RF sensor. Thus, the developed equipment is expected that the unit can be used in many practical applications with benefits in economical advantage to combine the use of both automatic and manual type because attachment is possible existent manual remote exposure controller, AC and DC combined use.
Development of Real-Time Thickness Measuring System for Insulated Pipeline Using Gamma-ray
Jang, Ji-Hoon ; Kim, Byung-Joo ; Kim, Gi-Dong ; Cho, Kyung-Shik ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 500~507
By this study, on-line real-time radiometric system was developed using a 64 channels linear array of solid state detectors to measure wall thickness of insulated piping system. This system uses an Ir-192 as a gamma ray source and detector is composed of BGO scintillator and photodiode. Ir-192 gamma ray source and linear detector array mounted on a computer controlled robotic crawler. The Ir-192 gamma ray source is located on one side of the piping components and the detector array on the other side. The individual detectors of the detector array measure the intensity of the gamma rays after passing through the walls and the insulation of the piping component under measurement. The output of the detector array is amplified by amplifier and transmitted to the computer through cable. This system collects and analyses the data from the detector array in real-time as the crawler travels over the piping system. The maximum measurable length of pipe is 120cm/min. in the case of 1mm scanning interval.
Effects of Rubber Loading on the Ultrasonic Backward Radiation Profile of Leaky Lamb Wave
Song, Sung-Jin ; Kwon, Sung-Duk ; Jung, Min-Ho ; Kim, Young-H. ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 508~515
The characterization of adhesive property in multi-layer materials has been hot issue for a long time. In order to evaluate adhesive properties, we constructed fully automated system for the backward radiation of leaky Lamb wave. The backward radiation profiles were obtained for the bare steel plate and plates with rubber-loading. The rf waveforms and frequency spectra of backward radiation show the characteristics of involved leaky Lamb wave modes. As the thickness of rubber-loading increased, the amplitude of profile at the incident angle of
exponentially decreased. Scanning the incident position over the partially rubber-loaded specimen shows good agreement with the actual rubber-loading. The backward radiation of leaky Lamb wave has great potential to evaluate the adhesive condition as well as material properties of plates.
Spherical Indentation Testing to Evaluate Mechanical Properties in 1Cr-1Mo-0.25V Steel
Lee, Jong-Min ; Lee, Seung-Seok ; Lee, Ouk-Sub ; Nam, Young-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 516~522
For the experimental study of rotor steel, seven kind of specimens with different degradation levels were prepared by isothermal heat treatment at
. Spherical indentation technique was developed to evaluate the flow properties of metallic materials in carbon steel, stainless steel, and alloys, etc. Through the spherical indentation test, differently degraded 1Cr-1Mo-0.25V steel's mechanical properties were observed and compared with conventional standard test data. The flow properties of 1Cr-1Mo-0.25V steel's were estimated by analyzing the indentation load-depth curve. To characterize the flow property, we used material yield slope and constraint factor index rather than strain-hardening exponent because the variation of strain-hardening exponent was very little and the data showed irregularly. And the constraint factor's effect was small when the material yield slope was taken into account.
Development of Real-Time Image Processing Algorithm on the Positions of Multi-Object in an Image Plane
Jang, W.S. ; Kim, K.S. ; Lee, S.M. ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 523~531
This study is concentrated on the development of high speed multi-object image processing algorithm in real time. Recently, the use of vision system is rapidly increasing in inspection and robot's position control. To apply the vision system, it is necessary to transform the physical coordinate of object into the image information acquired by CCD camera. Thus, to use the application of the vision system to the inspection and robot's position control in real time, we have to know the position of object in the image plane. Particularly, in case of rigid body using multi-cue to identify its shape, the each position of multi-cue must be calculated in an image plane at the same time. To solve these problems, the image processing algorithm on the position of multi-cue is developed.
Classification of Acoustic Emission Signals for Fatigue Crack Opening and Closure by Artificial Neural Network Based on Principal Component Analysis
Kim, Ki-Bok ; Yoon, Dong-Jin ; Jeong, Jung-Chae ; Lee, Seung-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 532~538
This study was performed to classify the fatigue crack opening and closure for three kinds of aluminum alloy using principal component analysis (PCA). Fatigue cycle loading test was conducted to acquire AE signals which come from different source mechanisms such as crack opening and closure, rubbing, fretting etc. To extract the significant feature from AE signal, correlation analysis was performed. Over 94% of the variance of AE parameters could accounted for the first two principal components. The results of the PCA on AE parameters showed that the first principal component was associated with the size of AE signals and the second principal component was associated with the shape of AE signals. An artificial neural network (ANN) an analysis was successfully used to classify AE signals into six classes. The ANN classifier based on PCA appeared to be a promising tool to classify AE signals for fatigue crack opening and closure.
The Change of Full Width Half Maximum and Residual Stress during Fatigue Process in S45C Steel
Boo, Myung-Hwan ; Park, Young-Chul ; Kim, Byeong-Soo ; Lee, Jong-Moon ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 539~544
The purpose of this study is to examine the change of full width half maximum(FWHM) and residual stress during fatigue process in S45C Steel, by X-ray diffraction. For S45C Steel, the relationship between the change in fatigue damage of the specimen and the FWHM, and residual stress of X-ray diffraction profiles during the fatigue processes has been investigated. The FWHM decreases in the early period of fatigue cycle. The change of FWHM is associated with cyclic work hardening. The change of the FWHM is not significant in
of ratio of fatigue life. The residual stress is changed with fatigue cycle increasing during the fatigue pro process.
Comparison and Analysis of Tomography Methods for Reconstruction of Three-dimensional Density Distributions in Two-phase Flows
Ko, Han-Seo ; Kim, Yong-Jae ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 545~556
Bubble behaviors in two-phase flows have been analyzed by tomography methods such as an algebraic reconstruction technique (ART) and a multiplicative algebraic reconstruction technique (MART). Initially, a bubbly flow and an annular flow have been investigated by cross-sectional view using computer synthesized phantoms. Two tomography methods have been compared to obtain more accurate results of the two-phase flows. Then, reconstruction of three-dimensional density distributions of phantoms with two and three bubbles have been accomplished by the MART method which provided the better results for the two-dimensional reconstructions accurately to analyze the bubble behaviors in the two-phase flow.
Non-destructive Testing (NDT) Using Synchrotron Radiation
Chang, Suk-Sang ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 5, 2002, Pages 557~563