• Composites Research
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• v.34 no.5
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• pp.323-329
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• 2021

In this paper, the characteristics of fracture in mode I loading were analyzed for adhesively bonded joints with non-uniform adhesion. The Double Cantilever Beam test was performed and mode I fracture toughness was obtained. In the case of non-uniform adhesively bonded joints, the stable crack growth sections and unstable crack growth section were shown. The fracture characteristics of each section were observed through the load-displacement curve of the DCB test and the fracture surface of the specimen. Finite Element Analysis was performed at the section based on segmented section by crack length measured through the test and using the mode I fracture toughness of each section. Through DCB test results and finite element analysis results, it was confirmed that the fracture behavior of specimens with non-uniform adhesion can be simulated.

• Geomechanics and Engineering
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• v.28 no.6
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• pp.613-624
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• 2022

A study of the evolution of overburden fractures under the solid-fluid coupling state was conducted based on the geological and mining characteristics of the coal seam depth, weak strata cementation, and high-intensity mining in the mining areas of West China. These mining characteristics are key to achieving water conservation during mining or establishing groundwater reservoirs in coal mines. Based on the engineering background of the Daliuta Coal Mine, a non-hydrophilic simulation material suitable for simulating the weakly cemented rock masses in this area was developed, and a physical simulation test was carried out using a water-sand gushing test system. The study explored the spatial distribution and dynamic evolution of the fractured zone in the mining overburden under the coupling of stress and seepage. The experimental results show that the mining overburden can be vertically divided into the overall migration zone, the fracture extension zone and the collapse zone; additionally, in the horizontal direction, the mining overburden can be divided into the primary fracture zone, periodic fracture zone, and stop-fracture zone. The scope of groundwater flow in the overburden gradually expands with the mining of coal seams. When a stable water inrush channel is formed, other areas no longer generate new channels, and the unstable water inrush channels gradually close. Finally, the primary fracture area becomes the main water inrush channel for coal mines. The numerical simulation results indicate that the overlying rock breaking above the middle of the mined-out area allows the formation of the water-conducting channel. The water body will flow into the fracture extension zone with the shortest path, resulting in the occurrence of water bursting accidents in the mining face. The experimental research results provide a theoretical basis for the implementation of water conservation mining or the establishment of groundwater reservoirs in western mining areas, and this theoretical basis has considerable application and promotion value.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.816-819
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• 1997

The operation of femoral non-union after IM(Intramedullary) nailing in distally femoral fractures is considered. Augmentive plate fixation is the management of femoral non-union after IM nailing. The purpose of this study is to compare the bending, torsional stiffness and stress distribution of the two operations by the FEM(Finite Element Method). Augmentive plate fixation is better than IM nail fixation. These results conclude that plate augmentation is a useful method for the unstable femoral non-union after interlocking IM nailing.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.3
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• pp.78-89
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• 1989

Applicability of tearing modulus based on J-integral proposed by Paris et al is investigated using compact tension specimens of strutural alloy steel (SCM4). Both general fracture test and instability fracture test are performed. The applied tearing modulus, ( $T_{j}$)app estimated from the real load vs. crack growth curve measured from experiments are compared with that estimated from the limit load vs. crack growth curve. The results are : (1) the $T_{j}$parameter could be applied to predict crack growth instability : (2) The use of ( $T_{j}$)app estimated from the load vs. crack growth curve, proposed in this study could be well predicted crack growth instability instead of that estimated form the limit load vs. crack growth curve.e.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.181-187
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• 2000

Fatigue tests under acid fog environment were carried out to investigate the effect of acid fog on the corrosion fatigue strength of SM55C in comparison with distilled water. Main results obtained are as follows. The fatigue strength of SM55C under acid fog environment are remarkably decreased as compared with that of distilled water specimen. The corrosive effect of acid fog on fatigue strength are more serious under low stress amplitude level than under high stress amplitude level, and this leads to continuous reduction of fatigue strength. Under acid fog environment in early stage of crack growth. because the corrosive components dissolve the crack face offensively. the unstable fracture surface appears. But, the stable corrosion precipitation and products layer are formed on the fracture surface in accordance with the time pass.

• Clinics in Shoulder and Elbow
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• v.8 no.2
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• pp.158-165
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• 2005

The Superior Shoulder Suspensory complex (SSSC) maintains a normal stable relationship between the upper extremity and the axial skeleton. Traumatic double disruptions of the SSSC frequently create an unstable anatomic situation and is difficult-to-treat. When this double disruption is managed conservatively, significant displacement can occur at either or both sites and result in long-term problems and functional disabilities. Therefore surgical management is generally necessary. The authors experienced two cases of double disruptions of the SSSC treated with arthroscopic surgery & and reported good results.

• Journal of Yeungnam Medical Science
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• v.19 no.2
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• pp.73-91
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• 2002

Method of management of the spine injury should be determined, based on the status of neurological injury as well as on the presence of traumatic instability. At the thoracic and lumbar spine, patterns of neurological injury are different from the cervical spine due to their neuro-anatomical characteristics. Especially, at the thoracolumbar junction, neurological injury patterns with their respective prognosis vary from the complete cord injury or conus medullaris syndrome to the cauda equina syndrome according to the injury level. The concept of Holdsworth's instability based on the posterior ligament complex theory has evolved into the current 3-column theory of Denis. Flexion-rotation injury and fracture-dislocation are well known to be unstable that surgical fixation is frequently needed for these injuries. However, there have been some controversies for the stability of burst fractures and their treatment, such as indirect or direct decompression and anterior or posterior approach. In this article, current concepts and management of traumatic instabilities at the thoracic and lumbar spine have been reviewed and summarized.

• Clinics in Shoulder and Elbow
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• v.11 no.1
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• pp.41-45
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• 2008

Purpose: To review the clinical and radiological results after an open reduction and internal fixation with a T-shaped LCP for unstable distal clavicle fractures. Materials and Methods: From February 2005 to June 2006, ten patients with distal clavicle Neer type II fractures were treated with an open reduction and internal fixation with a T-shaped LCP. Bony union was identified by plain radiography. The clinical results were analyzed according to the UCLA scoring system. Results: The mean time to fracture union was 9weeks and union was achieved in all cases. The mean UCLA score was 33.4 (30-35); excellent in 8 cases and good in 2 cases. In one case, loosening of one distal screw was occured and mild AC joint subluxation was observed in another case. Conclusion: 3.5 mm T-shaped LCP fixation is a useful technique for treating unstable distal clavicle fractures. This procedure provide stable fixation with no further AC joint injury.

• Clinics in Shoulder and Elbow
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• v.14 no.1
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• pp.1-5
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• 2011

Purpose: The purpose of this study was to evaluate the radiologic and clinical outcomes after operative treatment using endobuttons for unstable distal clavicle fractures. Materials and Methods: Between October 2007 and September 2009, 9 consecutive patients who were followed up for at least more than 12 months after operative treatment using a TightRope$^{(R)}$ were studied. The radiologic results on the serial plain radiographs and the clinical results according to the American Shoulder Elbow Surgeons (ASES) score were analyzed. Result: Bony union was shown in 8 cases (88.9%) and the average time to union was 12.9 (range: 9~16) weeks. The average coracoclavicular distances at the postoperative and final follow-up were 5.6 mm and 6.2 mm, respectively, with no statistically significant difference (p>0.05). The average ASES score was 90.3 (range: 78~96) and the clinical outcomes were 6 excellent, 2 good and one fair. There were no complications such as implant failure or infection except for one case of nonunion due to loss of the initial reduction. Conclusion: A major advantage of TightRope$^{(R)}$ fixation for unstable distal clavicle fractures is that no further surgery is needed to remove the implant. We suggest that this technique provides an alternative for fracture with a distal fragment, which is difficult to fix.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1285-1293
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• 1992

The fracture behavior of glass/epoxy plain woven composite plates containing circular holes is experimentally investigated to examine the effects of hole size and specimen width on notched tensile strength. It is shown in this paper that the characteristic length according to the point stress criterion depends on the hole size and specimen width. For predicting the notched tensile strength, a modified failure criterion is developed. An excellent agreement is found between the experimental results and the analytical prediction of modified failure criterion. The notched strength and the characteristic length have an increase and decrease relations. When the unstable fracture occured, the critical crack length equivalent for the damage zone size at the edge of hole is about twice the characteristic length. The critical energy release rate G$_{c}$ is independent of hole size(0.03 .leq. 2R/W .leq. 0.5) under the same specimen width. However G$_{c}$ increases with an increase in specimen width which can be explained by stress relaxation due to the notch insensitivity.ity.