• Journal of the Korean Institute of Gas
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• 제21권1호
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• pp.18-26
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• 2017

This work proposes an alternative pipe wall-thinning inspection method based on change of eigenfrequencies of shell vibration modes in wall-thinned pipes. It takes much time to detect wall-thinning of pipes using ultrasonic thickness gauge and only a limited number of pipes are under regular inspection. In a pipe with locally decreased thickness, stiffness varies along circumferential direction and natural frequencies of shell vibration modes of the pipe change or frequencies of same modes bifurcate into two different values. Therefore, one can monitor pipe wall-thinning by measuring change of natural frequencies or estimate wall-thinning shape qualitatively. The feasibility of the proposed method was studied by FE vibration analysis for wall-thinned pipes. Modal testing was also carried out for the pipes with artificial wall-thinned section to verify the working performance of the suggested technique.

• Journal of the Korean Society for Nondestructive Testing
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• 제32권2호
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• pp.170-176
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• 2012

In the nuclear industry, wall thinning defect of straight pipe occur the enormous loss in life evaluation and safety evaluation. To use non-destructive technique, we measure deformation, vibration, defect evaluation. But, this techniques are a weak that is the measurement of the wide area is difficult and the time is caught long. In the secondary side of nuclear power plants mostly used steel pipe, artificiality wall thinning defect make in the side and different thickness make to the each other, wall thinning defect part of deformation measure by using shearography. In addition, optical measurement through deformation, vibration, defect evaluation evaluate pipe and thickness defects of pressure vessel is to evaluate quantitatively. By shearography interferometry to measure the pipe's internal wall thinning defect and the variation of pressure use the proposed technique, the quantitative defect is to evaluate the thickness of the surplus. The amount of deformation use thickness of surplus prediction of the actual thickness defect and approximately 7 percent error by ensure reliability. According to pressure the amount of deformation and the thickness of the surplus through DB construction, nuclear power plant pipe use wall thinning part soundness evaluation. In this study, pressure vessel of thickness defect measure proposed nuclear pipe of wall thinning defect prediction and integrity assessment technology development. As a basic research defected theory and experiment, pressure vessel of advanced stability and soundness and maintainability is expected to contribute foundation establishment.

• Journal of Korean Society of Forest Science
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• 제109권3호
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• pp.350-360
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• 2020

The purpose of this study was to identify and prioritize the key indicators and drivers of forest thinning. The research for this study was designed in two-phases: 1) sequential, exploratory, mixed methods research that was initiated with a qualitative phase (Delphi technique), and 2) the quantitative phase (Analytic Hierarchy Process technique). Results indicated that management and planning were the most important factors in the first level of criteria among the "management and planning," "directing and monitoring," "supervision," and "quality of thinning work." On the sub-criteria level, "the quality of forest management planning" was indicated as the most important factor among the ten sub-criteria. Our results have shown that the developed forest thinning evaluation factors were a well-represented characteristic for a variety of forest thinning work in Korea.

• Journal of the Korean Society for Nondestructive Testing
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• 제33권4호
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• pp.361-367
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• 2013

Many of the nuclear power plant pipe is used in high temperature and high pressure environment. Wall thinning frequently caused by the corrosion. These wall thinning in pipe is expected gradually increase as nuclear power become superannuated. Therefore there is need to evaluate wall thinning in pipe and corrosion defect by non-destructive method to prevent the accident of the nuclear power facility due to pipe corrosion. Especially for real-time assessment of the wall thinning that occurs in nuclear power plant pipe, the laser ultrasonic technology can be measured even in hard-to-reach areas, beyond the limits of earlier existing contact methods. In this study, the optical method using laser was applied for non-destructive and non-contact evaluation. Ultrasonic signals was acquired through generating ultrasonic by pulse laser and using laser interferometer. First the ultrasonic signal was detected in no wall thinning in pipe, then a longitudinal wave velocity was measured inside of pipe. Artificial wall thinning specimen compared to 20, 30, 40 and 50% of thickness of the pipe was produced and the longitudinal wave velocity was measured. It was possible to evaluate quantitatively the wall thinning area(internal defect depth) cause it was able to calculate the thickness of each specimen using measured longitudinal wave velocity.

• Proceedings of the KSRS Conference
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.643-646
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• 2006

This paper addresses the approach to extract linear features from satellite imagery using an efficient segmentation method. The extraction of linear features from satellite images has been the main concern of many scientists. There is a need to develop a more capable and cost effective method for the Iranian map revision tasks. The conventional approaches for producing, maintaining, and updating GIS map are time consuming and costly process. Hence, this research is intended to investigate how to obtain linear features from SPOT satellite imagery. This was accomplished using a discontinuity-based segmentation technique that encompasses four stages: low level bottom-up, middle level bottom-up, edge thinning and accuracy assessment. The first step is geometric correction and noise removal using suitable operator. The second step includes choosing the appropriate edge detection method, finding its proper threshold and designing the built-up image. The next step is implementing edge thinning method using mathematical morphology technique. Lastly, the geometric accuracy assessment task for feature extraction as well as an assessment for the built-up result has been carried out. Overall, this approach has been applied successfully for linear feature extraction from SPOT image.

• Journal of the Korean Society for Nondestructive Testing
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• 제31권3호
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• pp.278-286
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• 2011

The on-line monitoring for the wall thinning in secondary system has been considered one of main issues for the safety of nuclear power plants. To establish the on-line monitoring technique for the pipe wall thinning, the development of the ultrasonic transducer working in high-temperature is very important. In this investigation, the magnetostrictive transducer is concerned for high temperature condition up to $300^{\circ}C$. The magnetostrictive transducer has many advantages such as high working temperature, durability, cost-effectiveness, and shear waves, most of all. A thin Fe-Co alloy patch whose Curie temperature is over $900^{\circ}C$ was employed as a ferromagnetic material for magnetostriction. Wave transduction experiments in various temperature were carried out and the effect of bias magnets was considered together with the dry coupling performance of the transducer. From experimental results, consequently, it was found that the magnetostrictive transducer works stable even in high temperature up to $300^{\circ}C$ and can be a promising method for the on-line monitoring of the wall thinning in nuclear power plants.

• Journal of Practical Agriculture & Fisheries Research
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• 제17권1호
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• pp.133-144
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• 2015

A study was conducted to examine treatment method, proper concentration, and treatment time of gibberellin(GA₃) for human labor saving at harvest in 'Campbell Early' grapevine. Fruit berry thinning reduced labor by GA₃ 40ppm treatment of 5 days prior to full bloom, and, at GA₃ 10, 20, and 40ppm during full bloom, by 14.27~19.15 minutes/tree. Therefore, although labor was reduced by dipping treatment at 40ppm of 5 days prior to full bloom and 20 and 40 ppm during full bloom, severe shattering was observed at 40ppm dipping treatment, and soluble solids decreased, which suggests difficulty with commercialization. The result suggests that proper time and concentration of GA₃ fruit cluster dipping treatment at full bloom and 10 and 20ppm, respectively.

• Journal of Institute of Control, Robotics and Systems
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• 제12권5호
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• pp.450-456
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• 2006

Monte Carlo localization is known to be one of the most reliable methods for pose estimation of a mobile robot. Although MCL is capable of estimating the robot pose even for a completely unknown initial pose in the known environment, it takes considerable time to give an initial pose estimate because the number of random samples is usually very large especially for a large-scale environment. For practical implementation of MCL, therefore, a reduction in sample size is desirable. This paper presents a novel approach to reducing the number of samples used in the particle filter for efficient implementation of MCL. To this end, the topological information generated through the thinning technique, which is commonly used in image processing, is employed. The global topological map is first created from the given grid map for the environment. The robot then scans the local environment using a laser rangefinder and generates a local topological map. The robot then navigates only on this local topological edge, which is likely to be similar to the one obtained off-line from the given grid map. Random samples are drawn near the topological edge instead of being taken with uniform distribution all over the environment, since the robot traverses along the edge. Experimental results using the proposed method show that the number of samples can be reduced considerably, and the time required for robot pose estimation can also be substantially decreased without adverse effects on the performance of MCL.

• The Transactions of the Korean Institute of Electrical Engineers A
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• 제48권10호
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• pp.1349-1355
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• 1999

A power distribution facility map is drawn on cadastral map. Besides, grid lines are added on the map for sectionalization. For automatic recognition of the map, we first extract recognizing regions. In this paper, we propose an extraction method of recognizing regions by partially extending thinned image. The proposed method is consist of three phases, binarization phase, thinning phase and partial extending phase. The first phase generate a binary image using threshold value which is obtained by histogram analysis. The binary image contains many part of recognizing regions, but not all. The second phase generate thinned image which is generated by appling thinning operator to the binary image. And the third phase extends thinned image from terminal point until satisfying termination condition. The proposed method is tested on several power distribution facility maps, and the results are presented.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• 제4권2호
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• pp.96-102
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• 2011

In this study, we performed algorithm development of automatic symptom degree for patient with hallux valgus one of the representative foot disease of morden. And this study proposes an efficient automated technique that is different from the original analog diagnosis for treatment and surgery of hallux valgus using digital image process. And we used X-Ray images of both a normal and a patient with hallux valgus in the procedure. First, we marked the standard angle on the X-Ray image of normal through Overlap & Add technique. Then we created a standard image through thinning filter and roberts filter(edge detection algorithm). Second, we used sobel filter of edge detection algorithm on the X-Ray image of patient. Moreover, we went another overlap & add technique procedure with both normal and patient image that we made. With the output, we projected the display detection image onto the screen. Finally, with the display detection image, we could measure and project the diagnosis angle of hallux valgus. And this confirms that this method is much more practical and applicable for another orthopedics disease than the prior one.