• Journal of the Korean Arthroscopy Society
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• v.6 no.1
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• pp.25-30
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• 2002

Purpose : To evaluate the clinical results of displaced tibial intercondylar eminence fractures which were treated with transpatellar cannulated screw fixation. Materials and Methods : Ten patients with displaced tibial intercondylar eminence fractures were treated between December 1998 and May 2001 and then followed up for more than one year. They were treated arthroscopic reduction and fixation of fracture site by cannulated screw through the hole of nonarticular surface of inferior patella. They were prospectively evaluated with regard to their clinical and radiologic results. Results : Radiologic unions occurred at an average of 9.2 weeks. Average anterior displacements were 1.8 mm in stress x-rays and 1.1 mm in KT-2000 arthrometer. Average loss of extension was $4.1^{\circ}$. Functional results were excellent in 7 cases and good in 3 cases. Conclusion : Arthroscopic transpatellar cannulated screw fixation is one of the useful methods for the treatment of displaced tibial intercondylar eminence fractures.

• Journal of Korean Foot and Ankle Society
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• v.26 no.1
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• pp.16-21
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• 2022

When an ankle lateral malleolar fracture is accompanied by a deltoid ligament rupture without a medial malleolar fracture, such an injury is called a bimalleolar equivalent fracture. This means that even if there is no bony injury on the medial side, there may be functional instability of the ankle joint due to damage to the deltoid ligament. Manual or gravity external rotational stress radiography is used to differentiate an ankle bimalleolar equivalent fracture from an isolated lateral malleolar fracture. If the medial joint gap is widened on the stress radiography, the deltoid ligament injury can be diagnosed, and surgical treatment for fibula fractures is recommended. After open reduction of the fibula fracture (with syndesmotic fixation if needed), a decision on the repair of the deltoid ligament is taken depending on the surgeons' preference and intraoperative findings. The deltoid ligament repair is performed by inserting a suture anchor (or anchors) in the medial malleolus and fixing the deep and superficial deltoid ligaments to the medial malleolus. The only randomized study to evaluate the utility of deltoid ligament sutures in ankle fractures did not support the deltoid ligament suture, but the study itself had many limitations. An appropriately powered, randomized, controlled trial of the deltoid ligament repair with both patient-reported outcome and radiographic outcome evaluation is needed in the future.

• Journal of Korean Foot and Ankle Society
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• v.15 no.1
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• pp.22-26
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• 2011

Purpose: To report the effectiveness of adding distal fibular external rotation stress test on the traditional lateral stress Cotton test in evaluating distal tibiofibular syndesmotic injuries. Materials and Methods: We evaluated syndesmotic injuries with intraoperative stress test during treating ankle fractures from March 2009 to September 2010. External rotation of distal fibula using small elevator was added on traditional stress test in case of suspicious syndesmotic injury. We retrospectively reviewed and compared the results of each test in 44 cases for which we tried both tests. Results: In 9 cases of positive traditional lateral stress tests, positive results were obtained in all cases by additional external rotation tests. In 21 cases of negative traditional stress tests, additional stress tests results were also negative. But there were 10 cases of positive additional tests and 4 of negative additional tests in equivocal results cases by the traditional stress tests. Conclusion: Using additional external rotation stress test in case of equivocal test result by the traditional lateral stress Cotton test for evaluation of syndesmotic injury during operation for ankle fracture can be a supplemental method to clarify syndesmotic injury needs fixation.

• Tunnel and Underground Space
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• v.17 no.2 s.67
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• pp.128-138
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• 2007

At low in-situ stress, the continuity and distribution of natural fractures in rock mass predominantly control the failure processes. However at high in-situ stress, the failure process are affected and eventually dominated by stress-induced fractures preferentially growing parallel to the excavation boundary. This fracturing is often observed in brittle type of failure such as slabbing or spatting. Recent studies on the stress- or excavation-induced damage of rock revealed its importance especially in a highly stressed regime. In order to evaluate the brittle failure around a deep underground opening, physical model experiments were carried out. For the experiments a new tue triaxial testing system was made. According to visual observation and acoustic emission detection, brittle failure grades were classified under three categories. The test results indicate that where higher horizontal stress, acting perpendicular $(S_{H2})$ and parallel $(S_{H1})$ to the axis of the tunnel respectively, were applied, the failure grade at a constant vertical stress level (Sy) was lowered. The failure initiation stress was also increased with the increasing $S_{H1}\;and\;S_{H2}$. From the multi-variable regression on failure initiation stress and true triaxial stress conditions, $f(S_v,\;S_{H1},\;S_{H2})$ was proposed.

• Tunnel and Underground Space
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• v.21 no.2
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• pp.117-127
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• 2011

The purpose of this study is to demonstrate the effect of in-situ rock stresses on the deformability and permeability of fractured rocks. Geological data were taken from the site investigation at Forsmark, Sweden, conducted by Swedish Nuclear Fuel and Waste Man-agement Company (SKB). A set of numerical experiments was conducted to determine the equivalent mechanical properties (essentially, elastic moduli and Poisson's ratio) and permeability, using a Discrete Fracture Network-Discrete Element Method (DFN-DEM) approach. The results show that both mechanical properties and permeability are highly dependent on stress because of the hyperbolic nature of the stiffness of fractures, different closure behavior of fractures, and change of fluid pathways caused by deformation. This study shows that proper characterization and consideration of in-situ stress are important not only for boundary conditions of a selected site but also for the understanding of the mechanical and hydraulic behavior of fractured rocks.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.199-210
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• 2008

Acoustic emission(AE)/Microseimsic(MS) activities are low-energy seismic events associated with a sudden inelastic deformation such as the sudden movement of existing fractures, the generation of new fractures or the propagation of fractures. These events rapidly increase before major failure and happen within a given rock volume and radiate detectable seismic waves. The main difference between AE and MS signals is that the seismic motion frequencies of AE signals are higher than those of MS signals. As the failure of geotechnical structures usually happens as a high velocity and small displacement, it is not easy to determine the precursor and initiation stress level of failure in displacement detection method. To overcome this problem, AE/MS techniques for detection of structure failure and damage have recently adopt in civil engineering. In this study, AE/MS monitoring system, which consist of sensor, data acquisition and operation program, is constructed with domestic technology. To verify and optimize the developed system, we are now carrying out the field application at an underground research laboratory and the developed AE/MS monitoring will be used in detecting of seismic events with various scales.

• Geomechanics and Engineering
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• v.18 no.5
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• pp.481-492
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• 2019

Due to the underground openings, the tangentially concentrated stress of the tunnel remains larger at excavation boundary and decreases toward the interior of the surrounding rock with a certain gradient. In order to study the effect of different gradient stress on rockburst, the true-triaxial gradient and hydraulic-pneumatic combined test apparatus were carried out to simulate the rockburst processes. Under the different gradient stress conditions, the rock-like specimen (gypsum) was tested independently through three principal stress directions loading--fast unloading of single surface--top gradient and hydraulic-pneumatic combined loading, which systematically analyzed the macro-mesoscopic damage phenomena, force characteristics and acoustic emission (AE) signals of the specimen during rockburst. The experimental results indicated that the rockburst test under the gradient and hydraulic-pneumatic combined loading conditions could perfectly reflect the rockburst processes and their stress characteristics; Relatively high stress loading could cause specimen failure, but could not determine its mode. The rockburst under the action of gradient stress suggested that the failure mode of specimen mainly depended on the stress gradient. When the stress gradient was lower, progressive and static spalling failure occured and the rockburst grades were relatively slight. On the other hand, shear fractures occurred in rockbursts accounted for increasingly large proportion as the stress gradient increased and the rockburst occurred more intensely and suddenly, the progressive failure process became unconspicuous, and the rockburst grades were moderate or even stronger.

• Journal of Korean Neurosurgical Society
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• v.51 no.6
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• pp.388-390
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• 2012

There has been no report of bilateral pedicle stress fractures involving two vertebrae. The authors describe a unique case of spondylolisthesis accompanying a bilateral pedicle stress fracture involving two vertebrae. De novo development of spondylolisthesis at the L5-S1 vertebrae accompanying a bilateral pedicle stress fracture at L4 and L5 was observed in a 70-year-old woman. The patient's medical history was unremarkable and she did not have any predisposing factors except severe osteoporosis. Interbody fusion with bone cement augmented screw fixation was performed. Surgical treatment resulted in good pain management and improved functional recovery.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.3
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• pp.207-217
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• 2010

The purpose of this study was to evaluate the effects of the stress distribution and displacement in mandible according to treatment modalities of mandibular angle fractures, using a three dimensional finite element analysis. A mechanical model of an edentulous mandible was generated from 3D scan. A 100-N axial load and four masticatory muscular supporting system were applied to this model. According to the number, location and materials of titanium and biodegradable polymer plates, the experimental groups were divided into five types. Type I had a single titanium plate in the superior border of mandibular angle, type II had two titanium plates in the superior tension border and in the inferior compression border of mandibular angle, type III had a single titanium plate in the ventral area of mandibular angle, type IV had a single biodegradable polymer plate in the superior border of mandibular angle, type V had a single biodegradable polymer plate in the ventral area of mandibular angle. The results obtained from this study were follows: 1. Stress was concentrated on the condylar neck of the fractured side except Type III. 2. The values of von-Mises stress of the screws were the highest in the just-posterior screw of the fracture line, and in the just-anterior screw of Type III. 3. The displacement of mandible in Type III was 0.04 mm, and in Type I, II, IV, and V were 0.10 mm. 4. The plates were the most stable in the ventral area of mandibular angle (Type III, V). In conclusion, the ventral area of mandibular angle is the most stable location in the fixation of mandibular angle fractures, and the just- posterior and/or the just-anterior screws of the fracture line must be longer than the other, and surgeons have to fix accurately these screws, and the biodegradable polymer plate also was suitable for the treatment of mandible angle fracture.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1730-1737
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• 1994

Theoretical equations for an influence of fiber breaks on the frictional heating phenomenon in a uniaxially fiber-reinforced ceramic matrix composite are formulated. The microslip and gross slip phases are considered for deriving the equations. During a complete loading/unloading cycle, the work done against friction is derived. In order to estimate interfacial shear in a unidirectionally reinforced ceramic matrix composite which has fiber fractures as well as matrix cracks, parametric studies using the derived equations are done. In a case of less than 10% fiber fractures, additional frictional work due to fiber breaks can be neglected compared to the rest.