• International journal of steel structures
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• v.18 no.4
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• pp.1363-1372
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• 2018

Recently, there have been studies about the increasing effect on the local plate buckling strength of flat plates when longitudinally stiffened with closed-section ribs and an approximate solution to quantitatively estimate these effects were suggested for flat plates. Since there are few studies to utilize such increasing effect on curved panels and a proper design method is not proposed, thus, this study aims to numerically evaluate such effect due to the rotational stiffness of closed-section ribs on curved panels and to propose an approximate method for estimating the buckling strength. Three-dimensional finite element models were set up using a general structural analysis program ABAQUS and a series of parametric numerical analyses were conducted in order to examine the variation of buckling stresses along with the rotational stiffness of closed-section ribs. By using a methodology that combine the strength increment factor due to the restraining effect by closed-section ribs and the buckling coefficient of the panel curvature, the approximate solutions for the estimation of buckling strength were suggested. The validity of the proposed methods was verified through a comparative study with the numerical analysis results.

• Journal of Electrodiagnosis and Neuromuscular Diseases
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• v.20 no.2
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• pp.153-158
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• 2018

Posterior interosseus (PI) nerve compression is a rare form of compressive neuropathy. It can cause pain along the radial nerve course and weakness of radial nerve innervating muscles without sensory symptoms. A 65-year-old man visited our institution complaining weakness of finger extension and thumb abduction after 2 times of injections at the right elbow in local clinic. The patient's clinical history and physical examination implied an iatrogenic radial nerve injury caused by the injection. The electrophysiologic study revealed of posterior interosseus neuropathy (PIN) with incomplete conduction block. However, the ultrasound study showed that the PI nerve was compressed by an anechoic cyst. The magnetic resonance imaging also confirmed of a ganglion cyst, not a hematoma. After repeated aspirations and a steroid injection, the electrophysiologic study showed recovery of motor weakness. Despite of the clue which implying an iatrogenic injury, clinician should consider other possibilities such as ganglion cysts and ultrasound guided aspiration and steroid injection could be an effective option for conservative management.

• Geomechanics and Engineering
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• v.24 no.1
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• pp.81-89
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• 2021

Uniaxial compression tests were conducted on sandstone-CGFB composite samples with different interface angles, and their strength, acoustic emission (AE), and failure characteristics were investigated. Three macro-failure patterns were identified: the splitting failure accompanied by local spalling failure in CGFB (Type-I), the mixed failure with small sliding failure along with the interface and Type-I failure (Type-II), and the sliding failure along with the interface (Type-III). With an increase of interface angle β measured horizontally, the macro-failure pattern changed from Type-I to Type-II, and then to Type-III, and the uniaxial compressive strength and elastic modulus generally decreased. Due to the small sliding failure along with the interface in the composite sample with β of 45°, AE events underwent fluctuations in peak values at the later post-peak failure stage. The composite samples with β of 60° occurred Type-III failure before the completion of initial compaction stage, and the post-peak stress-time curve initially exhibited a slow decrease, followed by a steep linear drop with peaks in AE events.

• Steel and Composite Structures
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• v.38 no.2
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• pp.165-176
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• 2021

Existing research on confined concrete filled steel tubular (CCFT) columns has been mainly focused on static or cyclic loading. In this paper, square section CCFT and CFT columns were tested under both static and impact loading, using a 10,000 kN capacity compression test machine and a drop weight testing equipment. Research parameters included bonded and unbonded fiber reinforced polymer (FRP) wraps, with carbon, basalt and glass FRPs (or CFRP, BFRP, and GFRP), respectively. Time history curves for impact force and steel strain observed are discussed in detail. Experimental results show that the failure modes of specimens under impact testing were characterized by local buckling of the steel tube and cracking at the corners, for both CCFT and CFT columns, similar to those under static loading. For both static and impact loading, the FRP wraps could improve the behavior and increase the loading capacity. To analyze the dynamic behavior of the composite columns, a finite element, FE, model was established in LS-DYNA. A simplified method that is compared favorably with test results is also proposed to predict the impact load capacity of square CCFT columns.

• Composite Materials and Engineering
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• v.3 no.3
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• pp.221-239
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• 2021

This paper presents a multiscale modeling method for sheet molding compound (SMC) composites through a novel bundle packing reconstruction algorithm based on a micro-CT (Computed Tomography) image processing. Due to the complex flow pattern during the compression molding process, the SMC composites show a spatially varying orientation and overlapping of fiber bundles. Therefore, significant inhomogeneity and anisotropy are commonly observed and pose a tremendous challenge to predicting SMC composites' properties. For high-fidelity modeling of the SMC composites, the statistical distributions for the fiber orientation and local volume fraction are characterized from micro-CT images of real SMC composites. After that, a novel bundle packing reconstruction algorithm for a high-fidelity SMC model is proposed by considering the statistical distributions. A method for evaluating specimen level's strength and stiffness is also proposed from a set of high-fidelity SMC models. Finally, the proposed multiscale modeling methodology is experimentally validated through a tensile test.

• Earthquakes and Structures
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• v.21 no.5
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• pp.505-514
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• 2021

A formulation based on structural reliability and cost effectiveness is proposed to provide recommendations to select the best retrofit strategy for schools with reinforced concrete frames and masonry walls, among three proposed alternatives. The cost calculation includes the retrofit cost and the expected costs of failure consequences. Also, the uncertainty of the seismic hazard is considered for each school site. The formulation identifies the potential failure modes, among shear and bending forces for beams, and flexure-compression forces for columns, for each school, and the seismic damages suffered by the schools after the earthquake of September 17, 2017 are taken into account to calibrate the damaged conditions per school. The school safety level is measured through its global failure probability, instead of only the local failure probability. The proposed retrofit alternatives are appraised in terms of the cost/benefit balance under future earthquakes, for the respective site seismic hazard, as opposed to the current practice of just restoring the structure original resistance. The best retrofit is the one that corresponds to the minimum value of the expected life cycle cost. The study, with further developments, may be used to develop general recommendations to retrofit schools located at seismic zones.

• Structural Engineering and Mechanics
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• v.83 no.4
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• pp.563-576
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• 2022

This study aimed to evaluate the progressive collapse potential of buildings designed using conventional design codes for the merchant occupancy classification and subjected to a sudden column failure. For this purpose, three reinforced concrete buildings having different story numbers were designed according to the seismic design recommendations of TSCB-2019. Later on, the buildings were analyzed using the GSA-2016 and UFC 4-023-03 to observe their progressive collapse responses. Three columns were removed independently in the structures from different locations. Nonlinear dynamic analysis method for the alternate path direct design approach was implemented for the design evaluation. The plasticity of the structural members was simulated by using nonlinear fiber hinges. The moment, axial, and shear force interaction on the hinges was considered by the Modified Compression Field Theory. Moreover, an existing experimental study investigating the progressive collapse behavior of reinforced concrete structures was used to observe the validation of nonlinear fiber hinges and the applied analysis methodology. The study results deduce that a limited local collapse disproportionately more extensive than the initial failure was experienced on the buildings designed according to TSCB-2019. The mercantile structures designed according to current seismic codes require additional direct design considerations to improve their progressive collapse resistance against the risk of a sudden column loss.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.1
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• pp.13-20
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• 2022

The lifetime incidence of epistaxis in dental and maxillofacial practice has been reported to be as high as 60% and can be caused by dental implant placement, Le Fort I osteotomy, intranasal supernumerary tooth, odontogenic tumors, blood disorders and maxillofacial trauma. Most epistaxis cases are minor and easily managed with direct compression on the nares for 10 minutes. For more significant or recurrent epistaxis, other techniques might include electrocautery, anterior or posterior nasal packing, or Foley catheter balloon. For patients with refractory epistaxis, cauterization of the sphenopalatine artery under endonasal endoscopy or embolization of the internal maxillary artery should be performed. Epistaxis control is required in patients diagnosed with inherited or acquired bleeding disorders or with drug-induced coagulopathies during dental procedures. In these cases, hemostatic system adjustment and hemostasis achieved by local and adjunctive methods are required. Dentists and maxillofacial surgeons must be aware that the nasal cavity is a potential source of perioperative hemorrhage. Depending on the invasiveness of the dental intervention, preoperative involvement of the hematologist and cardiologist is usually necessary to reverse anticoagulation or to cease anticoagulant therapy.

• Journal of Physiology & Pathology in Korean Medicine
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• v.37 no.6
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• pp.185-192
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• 2023

The purpose of this study is to analyze trends in domestic and international clinical research studies on pharmacopuncture treatment for fractures. We searched five online databases (PubMed, CNKI, RISS, KISS, and OASIS), and selected a total of 13 clinical research studies from Korea and China. Selected studies were analyzed according to publication year, subject, intervention, treatment method, evaluation scale, adverse event, risk of bias, etc. A total of 10 case studies and 3 randomized controlled trials were included. The study subjects were more often female, and the most common type of fracture was vertebral compression fracture. In Korea, herbal medicine preparations and bee venom were used for pharmacopuncture solution, whereas in China, both herbal medicine preparations and Western medicine preparations were used. All studies commonly used local acupoint needling, and in most cases, the treatment period for case study was less than 1 month, and the observation period of randomized controlled trials was diverse. The most frequently used evaluation scale was numeric rating scale, adverse events were mentioned in only three studies, and no adverse events were reported. Overall risk of bias of all included randomized controlled trials was judged "some concerns". According to this study, pharmacopuncture treatment for fractures was found to be relatively effective and safe, but research that complements the limitations of this study is needed.

• Steel and Composite Structures
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• v.50 no.2
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• pp.217-235
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• 2024

Concrete-filled steel tubes (CFSTs) nowadays are widely used as the main parts of momentous structures, and its connection has gained increasing attention as the complexity in configuration and load transfer mechanism. This paper proposes a novel CFST pier-to-footing incorporating tube-confined RC encasement. Such an innovative approach offers several benefits, including expedited on-site assembly, effective confinement, and collision resistance and corrosion resistance. The seismic behavior of such CFST pier-to-footing connection was studied by testing eight specimens under quasi-static cyclic lateral load. In the experimental research, the influences on the seismic behavior and the order of plastic hinge formation were discussed in detail by changing the footing height, axial compression ratio, number and length of anchored bars, and type of confining tube. All the specimens showed sufficient ductility and energy dissipation, without significant strength degradation. There is no obvious failure in the confined footing, while local buckling can be found in the critical section of the pier. It suggests that the footing provides satisfactory strength protection for the connection.