• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.389-392
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• 2004

It is clinically well known that pre-tension of wires increases the fracture stability in ring or hybrid external fixation. In some cases, additional half pin should be necessary to increase the stability when soft tissue impalement occurs during fixation. In this paper, the fracture stability of a hybrid external fixator system with different pre-tension effects and additional half-pins was analysed using FEM to investigate the effects of these pre-tension and half pin on the system stability quantitatively. 3-D finite element models of five different fixator frames were developed using by beam elements. In axial compression analysis, the fracture stiffness was increased maximally 62％ as the pre-tension increased. In torsion analysis, in the other hand, there is little variations in the fracture stiffness. Additional half pin increased the system stiffness about 200 ％. From the results, proper pre-tension and additional half pin would provide good methods to increase the fracture stability of the hybrid external fixator and provide more surgical options to minimize soft tissue damage at the fracture site.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.5
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• pp.217-223
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• 2013

Objectives: Buccal fracture of the mandibular proximal bone segment during bilateral sagittal split ramus osteotomy (SSRO) reduces the postoperative stability. The primary aim of this study is to evaluate the effect of this type of fracture on bone healing and postoperative stability after mandibular setback surgery. Materials and Methods: Ten patients who experienced buccal fracture during SSRO for mandibular setback movement were evaluated. We measured the amount of bone generation on a computed tomography scan, using an image analysis program, and compared the buccal fracture side to the opposite side in each patient. To investigate the effect on postoperative stability, we measured the postoperative relapse in lateral cephalograms, immediately following and six months after the surgery. The control group consisted of ten randomly-selected patients having a similar amount of set-back without buccal fracture. Results: Less bone generation was observed on the buccal fracture side compared with the opposite side (P<0.05). However, there was no significant difference in anterior-posterior postoperative relapse between the group with buccal fracture and the control group. The increased mandibular plane angle and anterior facial height after the surgery in the group with buccal fracture manifested as a postoperative clockwise rotation of the mandible. Conclusion: Bone generation was delayed compared to the opposite side. However, postoperative stability in the anterior-posterior direction could be maintained with rigid fixation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.2
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• pp.86-96
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• 2003

A fracture or breakage of the concrete armor units in the primary cover layer of breakwaters is studied by using the reliability analysis which may be defined as the structural stability. The reliability function can be derived as a function of the angle of rotation that represents the rocking of armor units quantitatively. The relative influences of all of random variables related to the material and geometric properties on the fracture of armor units is analyzed in detail. In addition, the probability of failure for the fracture of individual armor unit can be evaluated as a function of the incident wave height. Finally, Bernoulli random process and the allowable fracture ratio may be introduced together in this paper, by which the probability of failure of a breakwater due to the fracture of armer units can be obtained straightforwardly. It is found that the probability of failure of a breakwater due to the fracture of armor units may be varied with the several allowable fracture ratios. Therefore, it should be necessary to consider the structural stability as well as the hydraulic stability for the design of breakwaters with multi-leg slender concrete armor units of large size under wave action in deep water.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.96-104
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• 1989

The behaviors of acoustic emission emitted in the tests of the fracture toughness and fracture stability are observed by using the specimens of aluminum 2024-T351 and 7039-T6 alloys. The empirical eqution of J-R curve is derived. It is demonstrated from the comparison of the fracture toughness obtained from J-R curve with that from ASTM standard E813-81 that the latter is larger than the former. The discontinuous point in the log-log graph of J-integral vs. total acoustic emission count is observed in between the two offset lines referred from ASTM standard E813-81, but it's physical meaning is uncretain. An empirical material tearing modulus is derived in terms of the total acoustic emission count and proved to be valid in fracture instability test.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.790-791
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• 2006

The fracture behavior and mechanical characteristics of sintered rare-earth magnets were investigated. It shows that the fracture behavior and bending strength of the magnets obviously exhibit anisotropy. Sm-Co magnets tend to cleavage fracture in the close-packed (0001) plane or in the ($10\bar{1}1$) plane. The fracture mechanism of $Nd_2Fe_{14}B$ magnet mainly appears to be intergranular fracture. The anisotropy of fracture behavior and mechanical strength of sintered rare-earth magnets is caused mainly by the strong crystal-structure anisotropy and the grain alignment texture. The effects of Nd content, and Pr, Dy substitution on the impact stability of $Nd_2Fe_{14}B$ magnets were also reported.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2513-2516
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• 2012

This study examined the effects of the epoxidized castor oil (ECO) and $Al_2O_3$ content on the thermal stability and fracture toughness of the diglycidylether of bisphenol-A (DGEBA)/ECO/$Al_2O_3$ ternary composites using a range of techniques. The thermal stability of the composites was decreased by the addition of ECO and $Al_2O_3$ nanoparticles. The fracture toughness of the composites was improved significantly by the addition of ECO and $Al_2O_3$ nanoparticles. The composite containing 3 wt % $Al_2O_3$ nanoparticles showed the maximum flexural strength. Scanning electron microscopy (SEM) revealed tortuous cracks in the DGEBA/ECO/$Al_2O_3$ composites, which prevented deformation and crack propagation.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.149-154
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• 2002

An analytical fracture mechanics approach was used to investigate the fracture behavior of reinforced concrete beams. By use of this approach based on fracture mechanics concepts, the crack width and length as well as the strength and cracking stability of reinforced concrete beams were investigated. The results obtained from the analytical studies were also discussed in terms of the minimum reinforcement ratio and crack width specified in design code provisions. The analytical approach based on fracture mechanics concepts are very useful to predict the fracture behavior of reinforced concrete beams.

• Journal of Yeungnam Medical Science
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• v.18 no.1
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• pp.101-111
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• 2001

Background: We analyze the functional evaluation, posterior stability after surgery of acute injuries in the femoral detachment and tibial avulsion fracture of posterior cruciate ligament. Materials and Methods: Twenty two patients who underwent primary repair were followed more than one year after operation (mean follow-up 33.7 months). The patients were evaluated with KT 2000 arthrometer and posterior stress test for posterior stability. Lysholm knee score was used for knee function. Results: Lysholm score revealed 85.3 in femoral detachment group and 91.1 in tibial avulsion fracture group (P<0.05). Posterior displacement of the posterior stress test showed 17.2 mm at initial injury and 8.6 mm at last follow up in femoral detachment group, 16.8 mm at initial injury and 7.1 mm at last follow up in tibial avulsion fracture group. There revealed the tendency of the improved posterior stability of the tibial avulsion group compared with femoral detachment group, but there showed no statistical significance in KT 2000 arthrometer and posterior stress x-ray. Conclusion: Functional results of tibial avulsion fracture group revealed the better outcome compared with femoral detachment group, but the degree of posterior stability in tibial avulsion fracture group showed no statistical significance in posterior stability.

• Geomechanics and Engineering
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• v.12 no.3
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• pp.465-481
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• 2017

Thermal effect has great influence on wellbore stability in Dongfang 1-1 (DF 1-1) gas field, a reservoir with high-temperature and high-pressure. In order to analyze the wellbore stability in DF1-1 gas field, the variation of temperature field after drilling was analyzed. In addition, the effect of temperature changing on formation strength and the thermal expansion coefficients of formation were tested. On this basis, a wellbore stability model considering thermal effect was developed and the thermal effect on fracture pressure and collapse pressure was analyzed. One of the main challenges in this gas field is the decreasing temperature of the wellbore will reduce fracture pressure substantially, resulting in the drilling fluid leakage. If the drilling fluid density was reduced, kick or blowout may happen. Therefore, the key of safe drilling in DF1-1 gas field is to predict the fracture pressure accurately.

• Clinics in Shoulder and Elbow
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• v.19 no.4
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• pp.249-251
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• 2016

iepicondylar fracture of the humerus is very rare in adults. To date, there have been limited evidence of this injury in the English literature. We report a case of a 65-year-old female with a biepicondylar fracture of the left distal humerus without dislocation. Open reduction and internal fixation with K-wires, cannulated screw, and suture anchor were performed. We obtained stability of the elbow and a satisfactory functional outcome. Because this type of injury is associated with varus and valgus instability, operative reduction and fixation are essential in order to gain stability and early recovery of normal function.