• Geomechanics and Engineering
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• v.11 no.3
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• pp.345-359
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• 2016

In order to investigate the influence of the interfacial angel on failure characteristics and mechanism of combined coal-rock mass, 35 uniaxial/biaxial compressive simulation tests with 5 different interfacial angels of combined coal-rock samples were conducted by PFC2D software. The following conclusions are drawn: (1) The compressive strength and cohesion decrease with the increase of interfacial angle, which is defined as the angle between structure plane and the exterior normal of maximum principal plane, while the changes of elastic modulus and internal friction angle are not obvious; (2) The impact energy index $K_E$ decreases with the increase of interfacial angle, and the slip failure of the interface can be predicted based on whether the number of acoustic emission (AE) hits has multiple peaks or not; (3) There are four typical failure patterns for combined coal-rock samples including I (V-shaped shear failure of coal), II (single-fracture shear failure of coal), III (shear failure of rock and coal), and IV (slip rupture of interface); and (4) A positive correlation between interfacial angle and interface effect is shown obviously, and the interfacial angle can be divided into weak-influencing scope ($0-15^{\circ}$), moderate-influencing scope ($15-45^{\circ}$), and strong-influencing scope (> $45^{\circ}$), respectively. However, the confining pressure has a certain constraint effect on the interface effect.

• Earthquakes and Structures
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• v.26 no.4
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• pp.311-326
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• 2024

Transmission tower structures are particularly susceptible to damage and even collapse under strong seismic ground motions. Conventional seismic analyses of transmission towers are usually performed by considering only ground motion uncertainty while ignoring structural uncertainty; consequently, the performance evaluation and failure prediction may be inaccurate. In this context, the present study numerically investigates the seismic responses and failure mechanism of transmission towers by considering multiple sources of uncertainty. To this end, an existing transmission tower is chosen, and the corresponding three-dimensional finite element model is created in ABAQUS software. Sensitivity analysis is carried out to identify the relative importance of the uncertain parameters in the seismic responses of transmission towers. The numerical results indicate that the impacts of the structural damping ratio, elastic modulus and yield strength on the seismic responses of the transmission tower are relatively large. Subsequently, a set of 20 uncertainty models are established based on random samples of various parameter combinations generated by the Latin hypercube sampling (LHS) method. An uncertainty analysis is performed for these uncertainty models to clarify the impacts of uncertain structural factors on the seismic responses and failure mechanism (ultimate bearing capacity and failure path). The numerical results show that structural uncertainty has a significant influence on the seismic responses and failure mechanism of transmission towers; different possible failure paths exist for the uncertainty models, whereas only one exists for the deterministic model, and the ultimate bearing capacity of transmission towers is more sensitive to the variation in material parameters than that in geometrical parameters. This research is expected to provide an in-depth understanding of the influence of structural uncertainty on the seismic demand assessment of transmission towers.

• Journal of Yeungnam Medical Science
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• v.33 no.2
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• pp.162-165
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• 2016

Barium sulfate is an inert material used as a radiographic contrast medium during upper gastrointestinal contrast studies for evaluation of patients with dysphagia. Oral barium aspiration is an uncommon but well-reported complication of this procedure. While barium aspiration of small amounts may not cause any symptoms, massive barium aspiration can be life-threatening, particularly in elderly patients with multiple comorbidities. In this case report, we describe an elderly patient with multiple comorbidities who presented with thyrotoxicosis and dysphagia, and then died after massive barium aspiration. Despite administration of intensive medical care with ventilator support and therapeutic bronchoalveolar lavage to remove the aspirated barium, the patient died of multiple organ failure 9 days after barium aspiration. Clinicians should pay attention to elderly patients with predisposing factors for aspiration in whom upper gastrointestinal barium contrast studies are indicated, and should consider other diagnostic tools for evaluation of dysphagia in this population.

• Journal of Welding and Joining
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• v.23 no.3
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• pp.68-75
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• 2005

The fatigue life of welded joints is associated with crack initiation and propagation life. Theses cannot be easily separated, since the definition of crack initiation is vague due to the initiation of multiple cracks that are distributed randomly along the weld toes. In this paper a method involving a notch strain and fracture mechanical approach, which considers the characteristics of welded joints, e.g. welding residual stress and statistical characteristics of multiple cracks, is proposed, in an attempt to reasonably estimate these fatigue lives. The fatigue crack initiation life was evaluated statistically, e.g. the probability of failure occurrence in 2.3, 50 and $97.7\%$, in which the cyclic response of the local stress/strain hi the vicinity of the weld toes and notch factors derived by the irregular shape of the weld bead are taken into account. The fatigue crack propagation life was simulated by using Monte-Carlo method in consideration of the Ad-factor and the mechanical behavior of mutual interaction/coalescence between two adjacent cracks. The estimated total fatigue life, $(N_T)_{P50\%}$, as a sum of crack initiation and propagation life under the probability of failure occurrence in $50\%$ showed a good agreement with the experimental results. The developed technique for fatigue lift estimation enables to provide a quantitative proportion of crack initiation and propagation life in the total fatigue life due to the nominal stress range, ${\Delta}S$.

• Communications for Statistical Applications and Methods
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• v.6 no.2
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• pp.403-412
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• 1999

A block replacement policy where at failure the item is either replaced by a new or used item or remains inactive until the next planned replacement is considered. in this paper our interests are focused on reusing all the used items created by the policy. Numerical results for the case where the underlying life distribution is gamma are obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.1105-1106
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• 2009

• BMB Reports
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• v.46 no.5
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• pp.237-243
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• 2013

Heart failure is one of the leading causes of sudden death in developed countries. While current therapies are mostly aimed at mitigating associated symptoms, novel therapies targeting the subcellular mechanisms underlying heart failure are emerging. Failing hearts are characterized by reduced contractile properties caused by impaired $Ca^{2+}$ cycling between the sarcoplasm and sarcoplasmic reticulum (SR). Sarcoplasmic/endoplasmic reticulum $Ca^{2+}$ ATPase 2a (SERCA2a) mediates $Ca^{2+}$ reuptake into the SR in cardiomyocytes. Of note, the expression level and/or activity of SERCA2a, translating to the quantity of SR $Ca^{2+}$ uptake, are significantly reduced in failing hearts. Normalization of the SERCA2a expression level by gene delivery has been shown to restore hampered cardiac functions and ameliorate associated symptoms in pre-clinical as well as clinical studies. SERCA2a activity can be regulated at multiple levels of a signaling cascade comprised of phospholamban, protein phosphatase 1, inhibitor-1, and $PKC{\alpha}$. SERCA2 activity is also regulated by post-translational modifications including SUMOylation and acetylation. In this review, we will highlight the molecular mechanisms underlying the regulation of SERCA2a activity and the potential therapeutic modalities for the treatment of heart failure.

• Clinical and Experimental Pediatrics
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• v.57 no.8
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• pp.337-344
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• 2014

Inherited bone marrow failure syndrome (IBMFS) encompasses a heterogeneous and complex group of genetic disorders characterized by physical malformations, insufficient blood cell production, and increased risk of malignancies. They often have substantial phenotype overlap, and therefore, genotyping is often a critical means of establishing a diagnosis. Current advances in the field of IBMFSs have identified multiple genes associated with IBMFSs and their pathways: genes involved in ribosome biogenesis, such as those associated with Diamond-Blackfan anemia and Shwachman-Diamond syndrome; genes involved in telomere maintenance, such as dyskeratosis congenita genes; genes encoding neutrophil elastase or neutrophil adhesion and mobility associated with severe congenital neutropenia; and genes involved in DNA recombination repair, such as those associated with Fanconi anemia. Early and adequate genetic diagnosis is required for proper management and follow-up in clinical practice. Recent advances using new molecular technologies, including next generation sequencing (NGS), have helped identify new candidate genes associated with the development of bone marrow failure. Targeted NGS using panels of large numbers of genes is rapidly gaining potential for use as a cost-effective diagnostic tool for the identification of mutations in newly diagnosed patients. In this review, we have described recent insights into IBMFS and how they are advancing our understanding of the disease's pathophysiology; we have also discussed the possible implications they will have in clinical practice for Korean patients.

• Journal of The Korean Dental Society of Anesthesiology
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• v.2 no.2 s.3
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• pp.114-117
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• 2002

Special anesthetic considerations were required for children with acute or chronic liver disease. We experienced a case of dental treatment to control infection under general anesthesia in the 2-year-old girl with liver failure. She was also scheduled for liver tansplantation. Her preanesthetic results of liver function test, electrolytes, and coagulation panel were unstable and out of normal ranges. Uneventful anesthetic induction using isoflurane and atracurium and nasotracheal intubation were carried out. General anesthesia was maintained with isoflurane for 2 hours. Oozing from multiple extraction sites was sustained, so the transfusion of platelet concentration 1 units, fresh frozen plasma 1 unit, and packed red blood cell 1 unit was done. She was recovered without complication but was transferred to pediatric intensive care unit for wound care with her endotracheal tube kept. She was transferred to a ward without noticeable complications next day. So we report this successful case of anesthetic management for dental treatment in a child with liver failure.

• Korean Medical Education Review
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• v.16 no.2
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• pp.77-87
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• 2014

The purpose of this study was to investigate the influence of demographic data, academic demand, perfectionism, and academic failure tolerance on academic burnout of medical and graduate students at Yeungnam University. A mixed method study was conducted. Fourteen students participated in a focus group interview and 302 students, including 151 medical students and 151 graduate students, completed a survey, which addressed the factors of academic burnout, academic demand, perfectionism, and academic failure tolerance. There were significant differences in the academic burnout by age and year in school. The 2nd year medical & graduate students experienced significantly higher academic burnout than the other students. Multiple regression analysis revealed that academic burnout of medical and graduate students was significantly affected by academic demand (p<0.001), self-oriented and socially-prescribed perfectionism (p<0.001, p<0.01), and feeling and behavior, which were sub-factors of academic failure tolerance (p<0.05, p<0.01). It is suggested that comparative studies with other student groups, a longitudinal study of medical and graduate students, and a prospective study of coping styles and methods of preventing academic burnout need to be conducted.