• Clinics in Shoulder and Elbow
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• v.10 no.1
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• pp.124-130
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• 2007

The acromioclavicular separation (AC separation) is a common injury, which is often accompanied by the rupture of the coracoclavicular ligament (CC ligament) in severe occasions. In rare forms of AC separation, the fracture of the coracoid process would occur rather than the rupture of the CC ligament. Only 31 cases of such injury have been reported in the English literature. We present 2 additional cases with literature review. The fracture of the coracoid process is not readily seen on anteroposterior shoulder radiograms. Severe AC separation without widening of CC distance on anteroposterior shoulder radiogram heralds the fracture of the coracoid process.

• Journal of Yeungnam Medical Science
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• v.8 no.2
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• pp.121-127
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• 1991

We have reviewed seven cases of fracture-separation of the distal humeral epiphysis, one of which was initially misdiagnosed as a fracture of the lateral condyle. There were difficulties in making the diagnosis. The injury must be distinguished from an elbow dislocation and a fracture of the lateral humeral condyle. All seven patients revealed posteromedial displacenemt of the distal humeral epiphysis on initial x-rays. Three patients were treated by closed reduction and cast immmobilization, and four patients by open reduction and internal fixation. All three patients with conservative treatment had slight cubitus varus(under 5 degrees). Two patients with operative treatment had significant deformities of the elbow, one 25 degrees of valgus and one 20 degrees of varus. In treatment of these injuries, accurate evaluation of the state of reduction is most important. We got acceptable results with a conservative treatment.

• Structural Engineering and Mechanics
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• v.14 no.5
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• pp.565-574
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• 2002

This paper presents a method for predicting premature separation of carbon fiber reinforced plastic (CFRP) plates from strengthened steel beams. The fracture criterion based on material-induced singularity is formulated in terms of a singular intensity factor. Static test on double strap joints was selected to provide the critical stress intensity factor in the criterion because good degree of accuracy and consistency of experimental data can be expected compared with the unsymmetrically loaded single lap joints. The debond/separation loads of steel beams with different CFRP lengths were measured and compared with those predicted from the criterion. Good agreement between the test results and the prediction was found.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.238-245
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• 2000

Separation strips are temporary joints to prevent crack due to stress induced by shrinkage. In this study, an analysis procedure considering separation strip is proposed to decide proper casting time of separation strip and cracking stresses of the example building slabs are calculated using this procedure. The result of the example high rise building shows that the percentage of cracking stress to the modulus of fracture is 43.4% when closing of separation strip are 30 days after placing the slab, so it is enough time for the separation strip in each floor to absorb the effects of shrinkage.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.170-179
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• 2000

The objective of this study is to develop an analytical module for the prediction of burr formation during cutting process using the finite element method. This module is based on the rigid-plastic finite element method, ductile fracture criterion, fracture propagation technique and node separation criterion. The sequence of burr formation from burr initiation through end of burr formation is simulated and investigated by this module. The effect of material properties, such as AL6061-T6, AL2024-T4 and Copper, and cutting condition, such as rake angle and cutting depth, on burr formation is also discussed in this study. To validate this module the analysis results are compared with experimental ones.

• Geomechanics and Engineering
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• v.33 no.1
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• pp.11-18
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• 2023

This study explores a new energy partitioning approach to determine the fracture toughness of 3-D printed pristine/recycled high density polyethylene (HDPE) blends employing the essential work of fracture (EWF) concept. The traditional EWF approach conducts a uniaxial tensile test with double-edge notched tensile (DENT) specimens and measures the total energy defined by the area under a load-displacement curve until failure. The approach assumes that the entire total energy contributes to the fracture process only. This assumption is generally true for extruded polymers that fracture occurs in a material body. In contrast to the traditional extrusion manufacturing process, the current 3-D printing technique employs fused deposition modeling (FDM) that produces layer-by-layer structured specimens. This type of specimen tends to include separation energy even after the complete failure of specimens when the fracture test is conducted. The separation is not relevant to the fracture process, and the raw experimental data are likely to possess random variation or noise during fracture testing. Therefore, the current EWF approach may not be suitable for the fracture characterization of 3-D printed specimens. This paper proposed a new energy partitioning approach to exclude the irrelevant energy of the specimens caused by their intrinsic structural issues. The approach determined the energy partitioning location based on experimental data and observations. Results prove that the new approach provided more consistent results with a higher coefficient of correlation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.395-396
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• 2009

• Restorative Dentistry and Endodontics
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• v.37 no.4
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• pp.201-206
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• 2012

Objectives: The purpose was to investigate the preference and usage technique of NiTi rotary instruments and to retrieve data on the frequency of re-use and the estimated incidence of file separation in the clinical practice among general dentists. Materials and Methods: A survey was disseminated via e-mail and on-site to 673 general dentists. The correlation between the operator's experience or preferred technique and frequency of re-use or incidence of file fracture was assessed. Results: A total of 348 dentists (51.7%) responded. The most frequently used NiTi instruments was ProFile (39.8%) followed by ProTaper. The most preferred preparation technique was crown-down (44.6%). 54.3% of the respondents re-used NiTi files more than 10 times. There was a significant correlation between experience with NiTi files and the number of re-uses (p = 0.0025). 54.6% of the respondents estimated experiencing file separation less than 5 times per year. The frequency of separation was significantly correlated with the instrumentation technique (p = 0.0003). Conclusions: A large number of general dentists in Korea prefer to re-use NiTi rotary files. As their experience with NiTi files increased, the number of re-uses increased, while the frequency of breakage decreased. Operators who adopt the hybrid technique showed less tendency of separation even with the increased number of re-use.

• Computers and Concrete
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• v.24 no.1
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• pp.51-61
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• 2019

Compressive ability is one of the most important mechanical properties of concrete material. The compressive failure process of concrete is pretty complex with internal tension, shear damage and friction between cracks. To simulate the complex fracture process of concrete at meso level, methodology for meso-structural analysis of concrete specimens is developed; the zero thickness cohesive elements are pre-inserted to simulate the crack initiation and propagation; the constitutive applied in cohesive element is established to describe the mechanism of crack separation, closure and friction behavior between the fracture surfaces. A series of simulations were carried out based on the model proposed in this paper. The results reproduced the main fracture and mechanical feature of concrete under compression condition. The effect of key material parameters, structure size, and aggregate content on the concrete fracture pattern and loading carrying capacities was investigated. It is found that the inner friction coefficient has a significant influence on the compression character of concrete, the compression strength raises linearly with the increase of the inner friction coefficient, and the fracture pattern is sensitive to the mesostructure of concrete.

• Journal of Korean Neurosurgical Society
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• v.50 no.1
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• pp.11-16
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• 2011

Objective : The purpose of the present study was to determine the incidence of dural tears and predictable factors suggesting dural tears in patients who had lumbar burst fractures with vertical laminar fractures. Methods : A retrospective review was done on thirty-one patients who underwent operative treatment for lumbar burst fractures with vertical laminar fractures between January 2003 and December 2008. All patients were divided into two groups according to existence of dural tears, which were surgically confirmed; 21 patients with dural tears and 10 patients without dural tears. Clinical and radiographic findings were analyzed for their association with dural tears. Results : Among a total of 31 patients, dural tears were detected in 21 (67%) patients. A preoperative neurological deficits and mean separation distances of the edges in laminar fractures were found to be the reliable factors of dural tears (p=0.001 and 0.002, respectively). Decreased ratio of the central canal diameter and interpedicular distance were also the reliable factors suggesting dural tears (p=0.006 and 0.015, respectively). However, dural tears showed no significant association with age, sex, level of injury, absence of a posterior fat pad signal, the angle of retropulsed segment, or site of laminar fracture. Conclusion : Our study of lumbar burst fracture combined laminar fracture revealed that dural tears should be ruled out in cases of a preoperative neurological deficits, wide separation of the laminar fracture, severe canal encroachment, and wider interpedicular distance.