• Corrosion Science and Technology
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• v.8 no.4
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• pp.133-138
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• 2009

For the corrosion protection of the natural gas transmission pipelines, two methods are used, cathodic protection and coating technique. In the case of cathodic protection, defects are embrittled by occurring hydrogen at the crack tip or material surface. It is however very important to evaluate whether cracks in the embrittled area can grow or not, especially in weld metal. In this work, on the basis of elastic plastic fracture mechanics, we performed the CTOD testing with various test conditions, such as testing rate and potential. The CTOD of the base metal and the weld metal showed a strong dependence of the test conditions. The CTOD decreased with decreasing testing rate and with increasing cathodic potential. The morphology of the fracture surface showed the quasi-cleavage at low testing rate and cathodic overprotection. The low CTOD was caused by hydrogen embrittlement at crack tip.

• Journal of Mechanical Science and Technology
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• v.18 no.6
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• pp.915-923
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• 2004

This study investigated the fatigue lives and mechanical properties of the carbon black filled natural rubber for the vibration-proof parts of the railway vehicle and automobile. The carbon blacks were one of the sources of crack nucleation and crack propagation in the rubber matrix, like the cementite and the maganese sulfide in iron matrix. Different kinds of carbon blacks resulted in different fatigue lives, critical J-values, and fracture morphologies. It was noticed that the critical J-value remained almost the same regardless of the length of a pre-crack. In addition, different kinds of carbon blacks generated different fracture morphologies, and microscopic and macroscopic roughnesses. The critical J-value has linear relations to the roughness, and it seemed related to the size distribution of carbon black particles. By reviewing all the experi-mental data, we found the factors that were related to the fatigue lives, and the logarithmic value of the fatigue life could be linearly expressed by the combination of the critical J-value and the macroscopic roughness. We also proposed a new estimative equation of fatigue life.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.94-96
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• 2005

This paper is concerned with a fracture strength study of composite adhesive lap joints. The tensile and peel tests were carried out on specimen manufactured hybrid stacked composites such as the polyester and bamboo natural fiber layer. The main objective of the work was to test the failure strength of adhesive bonded joints using hybrid stacked composites with a polyester and bamboo natural fiber layer adjacent to the fiber orientation. From results, the load directional orientation, small amount and low thickness of bamboo natural fiber layer have a good effect on the tensile and peel strength of natural fiber reinforced composites. and these characters are have a great influence on fracture strength and failure shape of adhesive bonded joints using hybrid stacked composites in the difference of fiber orientation.

• Geomechanics and Engineering
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• v.11 no.3
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• pp.373-383
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• 2016

As one natural material, the physical and mechanical properties of rock will be affected very largely by chemical erosion environment. Under chemical environment, the strength of rock will be reduced. Considering the effect of the chemical erosion, fracture factor of rock is reduced. The damage variable is applied to express the change of fracture stress. Therefore, the fracture criterion of rock under chemical environment is constructed. By one experiment of rock fracture under chemical erosion environment, the proposed fracture criterion is verified. The results show that, the fracture path by theory is agree with the testing one well.

• Korean Journal of Clinical Pharmacy
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• v.29 no.3
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• pp.147-155
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• 2019

Objectives: The purpose of this study was to investigate the association between fracture risk and proton pump inhibitor (PPI) use to establish evidence for defining high-risk groups of fracture among PPI users. Methods: A case-control study was performed using the National Health Insurance Sample Cohort Database from January 2002 to December 2013. The cases included all incidences of major fractures identified from January 2011 to December 2013, and up to four controls were matched to each case by age, gender, osteoporosis, and Charlson comorbidity index. Conditional logistic regression was used to calculate the adjusted odds ratio (aOR) and associated 95% confidence interval (CI). Results: Overall, 14,295 cases were identified, and 63,435 controls were matched to the cases. The aOR of fractures related to the use of PPIs was 1.06 (95% CI: 1.01-1.11). There was a statistically significant association between fracture and PPI use within 3 months of the last dose, and a trend of increasing fracture risk with increasing cumulative PPI dose. The risk of fracture was significantly higher in patients who took PPIs for more than 1 year during the 2-year observation period. Conclusion: Patients who have been using PPIs for more than 1 year should be warned about the risk of fracture during or at least 3 months after discontinuing the PPI.

• Journal of Korean Neurosurgical Society
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• v.46 no.6
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• pp.584-587
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• 2009

Although most authors regard contralateral pedicular fracture with unilateral spondylolysis as an unstable condition and recommend surgical management when immobilization fails in promoting bony healing of the fracture, few researchers have investigated the natural history of pedicle fracture or the causal relationship between symptoms and the fracture. In addition, there are no detailed guidelines that address the management of this disease. We report a rare case of contralateral pedicular fracture associated with unilateral spondylolysis at the L5 level which was successfully treated by rehabilitation with activity modification.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.67-71
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• 2005

This paper is concerned with a study on fracture strength of composites in an adhesive single lap joint. The tests were carried out on joint specimens made with hybrid stacked composites consisting of the polyester and bamboo natural fiber layer. The main objective of this work was to evaluate the fracture properties adjacent to adhesive bonded joint of natural fiber reinforced composite specimens. From the results, natural fiber reinforced composites have lower tensile strength than the original polyester. But tensile-shear strength of natural fiber reinforced composites with bamboo layer far from adhesive bond is as high as that of the original polyester adhesive bonded joints. Spew filet at the end of the overlap reduced the stress concentration at the bonded area. Spew fillet and position of bamboo natural fiber layer have a peat effect on the tensile-shear strength of natural fiber reinforced composites including adhesive bonded joints.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.72-79
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• 2002

The effects of carbon black on the critical J-value and the surface fracture morpology of the carbon-black filled natural rubbers were investigated. Different kinds of carbon blacks resulted in different critical J-values, surface, and roughness. It was noticed that the critical J-value was almost the same regardless of the length of a pre-crack. In addition, different kinds of carbon blacks resulted in different fracture morphologies, and micro-scale and macro-scale roughnesses. The critical J-value could be linearly expressed by the micro-scale roughness and the macro-scale roughness and it seemed related to the size distribution of carbon black particles. And we also found that the macro-scale ms roughness was more sensitive than the micro-scale ms roughness to the critical J-value by the result of correlation coefficient, r$^2$.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.335-340
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• 2002

By the recently, Environmental pollution is serious by the highly economic growth and expansion of lively country basic industry. Especially, in case of industrial waste and life waste leaped into a pollution source. Also, research for processing of waste and recycling countermeasure is a pressing question on national dimension because it is prohibited an ocean disposal and reclamation. In this study, it looked for fracture characteristic value of recycling a coal ash to decrease environmental pollution by picky and exhaustion of natural resources and to reduce self-weight to prepare for a tall building and earthquake. So a coal ash examined to be possible to do as construction material. It achieved compressive strength test and three points bending test with initial notch depth rate and age for variables to show a basic research data. From the basis of the three points bending test, the fracture parameters - notch sensitivity, fracture energy, initial compliance were experimentally proposed. From the results of the compressive strength test, the elastic modulus was experimentally proposed. Also on the basis of the three points bending test, the fracture parameters - notch sensitivity, fracture energy, initial compliance were experimentally proposed. The results that the strength and fracture energy value are lower than concrete or mortar is described in this paper. Also, it shows that the deflection at fracture decreases as the age increases and the notch sensitivity decrease. However, it is judged to be available to construction material if research is continuously gone forward.

• The Journal of Engineering Geology
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• v.5 no.2
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• pp.201-213
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• 1995

Understanding of the fracture processes in rock mass for hydrogeology necessitates such information as fracture mechanics including genesis, propagation, termination, and the relation of fracture distribution to geologic structures and fracture modelling, etc. A current status of information on fracture for groundwater flow in rock mass, however, is very paucity except on a few special fields throughout the world. The desired and reasonable approach method in the evaluation on the groundwater flow in fractured rock mass must be based on the thorough understanding of fracture processes and a simplified model representing fracture properties which would be met to natural conditions for the interpretation and prediction.