• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.53-59
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• 2017

In this experimental study, the characteristic of damages on GFRP rebar exposed to high temperature only and immerged in alkaline solution after the exposure to high temperature was analyzed through microscopic image analysis. The found microcrack and pores in resin matrix were quantitatively compared if there was effect of pre-exposure to high temperature. The damages, such as microcrack and pores in resin matrix, by alkali exposure were mainly found in rebar surface. On the other hand, the pores caused by high temperatures were extensively found in a section and had greater width than those caused by the alkali exposure. In results of the quantitative comparison, the accumulated length and widths of microcrack and pores in resin matrix in pre-exposed GFRP rebar to high temperature were respectively 1.5 and 1.4 times of those in the GFRP rebar only immerged in alkali solution. Therefore, the deterioration of resin matrix by the alkali exposure could be accelerated due to the pre-exposure to high temperature.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.74-82
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• 2017

Localized corrosions damages in their structural sections can be occurred affected by installed environment conditions with high temperature as near the coastline and humidity or their poor maintenance situation. In bearing supports of steel bridges, especially, lower web and vertical stiffener in end girder support can be easily corroded because of relatively higher humidity due to the narrow space in the end of girder and the wetted accumulated sediments affected by rain water or antifreezing admixture leaked from expansion joint. It can be related to change in their structural performance. In this study, thus, bearing strength test specimens were fabricated considering corrosion damage in the web and vertical stiffeners and the change in their bearing strengths were experimentally evaluated. From the test results, localized corrosion damage of structural members in the end girder affected the bearing strength of end girder support, especially, localized corrosion damage of the vertical stiffener relatively highly affected their bearing strengths.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.1
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• pp.37-45
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• 2013

In this study, the resistance of various reinforced concrete (RC) slabs subjected to contact detonation was assessed. In order to enhance the blast resistance, fibers and external FRP sheets were reinforced to RC slabs. In the experiment, the $2,000{\times}1,000{\times}100mm$ sized RC slabs were fabricated using normal concrete (NC), steel fiber reinforced concrete (SFRC), polyvinyl alcohol fiber reinforced cementitious composite (PVA FRCC), and ultra-high performance cementitious composites (UHPCC). The damage levels of RC slabs subjected to contact detonation were evaluated by measuring the diameter and depth of crater, spall and breach. The experimental results were compared to the analyzed data using LS-DYNA program and three different prediction equations. The diameter and depth of crater, spall and breach were able to be predicted using LS-DYNA program approximately. The damage process of RC slabs under blast load was also well expressed. Three prediction equations suggested by other researchers had limitations to apply in terms of empirical approaches, therefore it needs further research to set more analytical considerations.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.10 no.1
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• pp.98-103
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• 2007

An 8-year-old boy presented with abdominal pain and poor oral intake for two months. Serum amylase and lipase levels were elevated. CT of the abdomen and chest X-ray showed two pseudocysts at the pancreatic uncinate process, pancreatitis with a parenchymal defect, a large amount of ascites, and a right pleural effusion. MR cholangiography and endoscopic retrograde cholangiopanreaticography revealed a pancreatic duct disruption. The patient was successfully treated with a chest tube placement and percutaneous drainage. After surgery, his general condition improved; the serum level of amylase normalized and the pleural effusion resolved. Pancreatic injuries are rare in pediatric blunt trauma; however, diagnostic difficulty is common with isolated blunt trauma. Therefore, a high index of suspicion should follow such an injury. We report the case of an 8-year-old boy with pancreas transection, ductal disruption, ascites, and pleural effusion who was successfully treated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.121-128
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• 2012

In this paper, nonlinear analysis for reinforced concrete structure for power transmission line is performed by considering the characteristics of the failure, which are depend on loading conditions and concrete material models. On the numerical evaluation for the failure behavior, the finite element analysis is applied. For the concrete material model, microplane model based on concrete damage is introduced. However, to describe the crack bridging effect of long and short fiber of steel fiber reinforced concrete (SFRC), tensile softening model is suggested and applied for SFRC. An numerical results by finite element technique are compared with the experiment results for box culvert specimen. Comparing on the experimental and analytical results, validity and reliability of numerical analysis are investigated.

• Korean Journal of Heritage: History & Science
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• v.46 no.4
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• pp.160-173
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• 2013

This research aims to understand the precise character of relics based on literature search and material analysis of the jade excavated from the first buried place of King Jung-jo, and to assess the level of damage through non-destructive diagnosis. Furthermore, scientific conservation treatment was used to restore the original shape of the excavated jade. According to literature search, the excavated jade is known to be jasper, but material analysis showed that it was as a serpentine with the mineral composition of antigorite. Infrared thermography analysis to assess deterioration showed that the internal damage is the result of the interstices developed along the boundary surface of the obtained jade. For conservation treatment of the damaged area on the surface, the jade was filled with a mixture of plaster and glue, and covered with a mixture of acrylic paint and gloss medium for protection, and color was adjusted.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.125-131
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• 2020

This study sought to reduce the risk of fractures in elite youth taekwondo athletes to find out the relationship between bone mineral density which are used as indicators of early diagnosis of osteoporosis and cardiorespiratory functional capacity which is an indicator of performance and sports injury the harmful to athletes. The Pearson product-moment correlation was performed to investigate the correlation between bone mineral density, cardiorespiratory functional capacity, and sports injury. The bone mineral density and cardiorespiratory functional capacity, sports injury were examined the relationship using the Simple Linear Regression. The bone mineral density were correlated with the ventilation (r=.388), and VO2max (r=.478). Bone mineral density was correlated with sports injury (r=-.292). When the bone mineral density increased by .002 and .006, the ventilation (p=.001) and VO2max (p=.006) increased by about 1. In addition, when the bone mineral density decline by .016, the sports injury increased by about 1. Improving athletes' bone mineral density can prevent sports injury, and it can be used as a sports injury prevention program in the future.

• Korean Journal of Biological Psychiatry
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• v.7 no.1
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• pp.46-54
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• 2000

Traumatic brain injury(TBI) is generally considered to be a risk factor for psychiatric disorders, especially depression and anxiety disorder. Despite the anxiety disorders are frequent sequelae after traumatic brain injury, the patients have not been payed medical attention and treated by doctors properly. The factors of precipitating and sustaining the anxiety disorders after TBI are brain injury itself, and the patient's or caregiver's response to the disability after TBI. To diagnose and treat them effectively, the knowledge about the mechanisms of and symptoms after TBI have to be needed. Psychiatrist should be a supportive and good listener to the patients who are complaining anxiety symptoms and differentiate whether the psychiatric symptoms are due to TBI or not. Because the TBI patients are very sensitive to drug side effects, doctors have to be familiar with the side effects as well as the mechanisms of action of the common psychotropics.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.31-38
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• 2003

In the present work, a nonlinear inverse perturbation method which has been used in the structural optimization, is adopted so as to identify the structural damages. Unlike the structural optimization, a larger number of constrained equations than the number of unknown parameters are often required detect structural damage. Therefore, nonlinear least squares method is utilized to solve the problem. Because only a limited number of sensors are available I real situation of damage detection, the determination of sensor location becomes one of the most important issues. Hence, this work concentrates on the issue of sensor placement in the framework of nonlinear inverse perturbation method, and the performances of various methodologies concerning to sensor placement are compared with each other. The comparisons show tat the successive elimination method gets good performance for sensor placement. From the several numerical studies, it is confirmed that the inverse perturbation method, combined with the successive elimination method, is very promising in structural damage detection.

• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.320-326
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• 2011

This paper proposes a baseline-free SHM technique in which the time-reversal process of Lamb waves and the imaging method are used. The proposed SHM technique has three distinct features when compared with the authors' previously proposed one: (1) It use the reconstructed signal for damage diagnosis, without need to extract the damage signal as the difference between reconstructed signal and initial input signal; (2) It use the imaging method based on the time-offlight information from the reconstructed signal, instead of using a pattern comparison method; (3) In order to make the damage image more clear, the modified mathematical definition of damage image in a pixel is used. The proposed SHM technique is evaluated through the damage detection experiment for an aluminum plate with damage at different locations.