• Journal of the Korean Society for Precision Engineering
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• v.26 no.11
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• pp.55-61
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• 2009

The wall thinning defect of nuclear power pipe is mainly occurred by the affect of the flow accelerated corrosion (FAC) of fluid. This type of defect becomes the cause of damage or destruction of in carbon steel pipes. Therefore, it is very important to measure defect which is existed not only on the welding part but also on the whole field of pipe. This study use dual-beam Shearography, which can measure the out-of-plane deformation and the in-plane deformation by using another illuminated laser beam and simple image processing technique. And this study proposes Infrared thermography, which is a two-dimensional non-contact nondestructive evaluation that can detect internal defects from the thermal distribution by the inspection of infrared light radiated from the object surface. In this paper, defect of nuclear power pipe were, measured using dual-beam shearography and infrared thermography, quantitatively evaluated by the analysis of phase map and thermal image pattern.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.144-149
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• 2015

This study aims to quantitatively evaluate failure pressure of wall-thinned elbow under combined load along with internal pressure, by conducting real-scale burst test and finite element analysis together. For quantitative evaluation, failure pressure data was extracted from the real-scale burst test first, and then finite element analysis was carried out to compare with the test result. For the test, the wall-thinning defect of the extrados or intrados inside the center of 90-degree elbow was considered and the loading modes to open or close the specimen maintaining a certain load or displacement were applied. Internal pressure was applied until failure occurred. As a result, when the bending load was applied under the load control condition, the intrados of the defect was more affected by failure pressure than the extrados, and the opening mode was more vulnerable to failure pressure than the closing mode. When the bending load was applied under the displacement control, it was hardly affected by failure pressure though it was slightly different from the defect position. The result of the finite element analysis showed a similar aspect with the test. Moreover, when major factors such as material properties and pipeline thickness were calibrated to accurate values, the analytical results was more similar to the test results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.826-828
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• 2014

Recently trend of product is miniaturization. As a result, We need products surface as well as products internal defect inspection. Generally, Inspection products in production process uses a lot of optical inspection. However, This is difficult to internal inspection of products. We used optical device instead of X-ray generator. At the same time, We have developed system to determine the product defect. First, obtain X-ray image from Machine vision function. Next, Measured value is recognize suitability within error range. otherwise recognize defect. Results presence of defective products can be stored by user.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.513-518
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• 2019

The non-destructive testing equipment using an eddy current was developed to check for defect in the vehicle transmission component. A defect master sample was made to test all types of defects that occur in the component and also an eddy current detector was manufactured and used to test and detect all kinds of defects. In addition, testing was held against the actual defective items to investigate the cause and type of defects, and a comparative study was conducted based on results from the examination. The software system of the eddy current detector was developed so that even a non-specialist can make assessment of detect in the component from the test results displayed on the monitor.

• Clinical Endoscopy
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• v.55 no.1
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• pp.58-66
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• 2022

Background/Aims: Anastomotic leakage after esophageal surgery remains a feared complication. During the last decade, management of this complication changed from surgical revision to a more conservative and endoscopic approach. However, the treatment remains controversial as the indications for conservative, endoscopic, and surgical approaches remain non-standardized. Methods: Between 2010 and 2020, all patients who underwent Ivor Lewis esophagectomy for underlying malignancy were included in this study. The data of 28 patients diagnosed with anastomotic leak were further analyzed. Results: Among 141 patients who underwent resection, 28 (19.9%) developed an anastomotic leak, eight (28.6%) of whom died. Thirteen patients were treated with endoluminal vacuum therapy (EVT), seven patients with self-expanding metal stents (SEMS) four patients with primary surgery, one patient with a hemoclip, and three patients were treated conservatively. EVT achieved closure in 92.3% of the patients with a large defect and no EVT-related complications. SEMS therapy was successful in clinically stable patients with small defect sizes. Conclusions: EVT can be successfully applied in the treatment of anastomotic leakage in critically ill patients, while SEMS should be limited to clinically stable patients with a small defect size. Surgery is only warranted in patients with sepsis with graft necrosis.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.2
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• pp.68-71
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• 2006

Active thermography has been used for several years in the field of remote non-destructive testing. It provides thermal images for remote detection and imaging of damages. Also, it is based on propagation and reflection of thermal waves which are launched from the surface into the inspected component by absorption of modulated radiation. For energy deposition, it use external heat sources (e.g., halogen lamp or convective heating) or internal heat generation (e.g., microwaves, eddy current, or elastic wave). Among the external heat sources, the ultrasound is generally used for energy deposition because of defect selective heating up. The heat source generating a thermal wave is provided by the defect itself due to the attenuation of amplitude modulated ultrasound. A defect causes locally enhanced losses and consequently selective heating up. Therefore amplitude modulation of the injected ultrasonic wave turns a defect into a thermal wave transmitter whose signal is detected at the surface by thermal infrared camera. This way ultrasound thermography(UT) allows for selective defect detection which enhances the probability of defect detection in the presence of complicated intact structures. In this paper the applicability of UT for fast defect detection is described. Examples are presented showing the detection of defects in PCB material. Measurements are performed on various kinds of typical defects in PCB materials (both Cu metal and non-metal epoxy). The obtained thermal image reveals area of defect in row of thick epoxy material and PCB.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.5
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• pp.400-408
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• 2003

This paper investigates the vibration characteristics of steam generator (SG) U-tubes with defect. The operating SG shell-side flow field conditions for determining the fluidelastic instability parameters such as added mass are obtained from three-dimensional SG flow calculation. Modal analyses are performed for the U-tubes either with axial or circumferential flaw with different sizes. Special emphases are on the effects of flaw orientation and size on the modal and instability characteristics of tubes, which are expressed in terms of the natural frequency, corresponding mode shape and stability ratio. Also, addressed is the effect of the internal pressure on the vibration characteristics of the tube.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.6
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• pp.373-377
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• 2000

For 6H-SiC single crystals which was obtained by sublimation growth (modified Lely process), the relation between the defects and the etch pits to be formed at the site of dislocations were discussed. Typical hexagonal etch pits were formed on (0001) basal plane. The similar hexagonal etch pit shapes were formed on the site of micropipe defects and it was realized that internal planar defects was formed with the same matrix crystal structure as grown crystals, through the observation of the etching morphology at those internal defects.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.271-281
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• 2010

Brazing fitting which is one of the aircraft hydraulic power system components is widely used for saving weight and achieving higher reliability. Any inherent defects or damage of fitting can cause system failure and/or physical damage of human body due to highly pressurized fluid. Radiographic testing(RT) technique and additional micro-structure investigation on cut-away surfaces have been accomplished to find out some defect-like-inhomogeneity in the fittings. The radiography results showed that some defect-like-inhomogeneity existed inside body. Additional micro-structure investigation on cut-away surface reveals that the inhomogeneity is due to internal voids. In this study, it can be is said that RT technique can be a useful tool for field acceptance test of hydraulic brazing fitting in short time.

• Journal of Chest Surgery
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• v.12 no.3
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• pp.225-232
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• 1979

A 15-year-old girl underwent successful surgical correction of double-outlet right ventricle [S.D.L.] subaortic ventricular septal defect, patent foramen ovale, and pulmonary hypoplasia with valvular stenosis. The operation consisted of an internal baffling connecting the left ventricle to the aorta through the ventricular septal defect. The pulmonary stenosis was corrected with the method of connection the right ventricle to the pulmonary artery bifurcation using the Hancock valve[18mm] contained conduit. This rare type of DORV seemed to be suitable for corrective surgery, and the patient`s condition is very good until present time (post operative 7 months).