• Tunnel and Underground Space
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• v.16 no.1 s.60
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• pp.26-37
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• 2006

This study addresses the applicability of box fractal dimension, $D_B$, as an index of statistical homogeneity of fractured rock mass. The box-count method's capability in quantifying the combined effect of fracture density and size distribution is examined systematically. Total of 129 two-dimensional fracture configurations were generated based on different combinations of fracture size distribution and fracture density. $D_B$was calculated for the generated fracture network systems using the box-counting method. It was found that was standard deviation of trace length and fracture orientation have no effect on calculated $D_B$. The estimated $D_B$ was found to increase with increasing total density and/or mean trace length. To explore the field applicability of this study, the statistical homogeneity of fractured rock mass was investigated at the rock slope and the underground facility using the box-counting method as well as conventional contingency table analysis. The results obtained in this study clearly show that the methodologies given in this paper have the capability of determining the statistical homogeneity of fractured rock mass.

• Journal of Korean Foot and Ankle Society
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• v.17 no.2
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• pp.130-135
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• 2013

Purpose: Preshaped Locking compression plate(LCP) has holes with fixed angle between screw and plate and have advantage firm fixation because it has stability of angular and axial deformity. We evaluated usefulness of LCP after open reduction and internal fixation in distal fibular fracture. Materials and Methods: Between December 2011 and May 2012, 23 patients with fracture of distal fibula were followed up at least 12 months underwent open reduction and internal fixation with LCP. There were 15 males and 8 females with a mean age 39.8(20~69) years. According to Danis-Weber classification, there were 20 cases of type B and 3 cases of type C. There were 13 cases of isolated lateral malleolus fractures, 1 case of bimalleolar fracture, 6 cases of trimalleolar fractures and 3 cases of distal tibia fractures with proximal fibula fracture. Intraoperatively, we assessed whether preshaped LCP fit lateral margin of distal fibula or not and evaluated quality of reduction and postoperative complications. The cases were analyzed by radiological bone union time and clinical results according to the criteria of Meyer Results: Of all cases, complete bone union was achieved and average radiological bone union time was 7.3(6~12) weeks. The clinical results were excellent in 18 cases(78%), good in 5 cases(22%). There were 5 cases of plate with 3 holes, 13 cases of plate with 4 holes, 2 cases of plate with 5 holes, 1 case of plate with 6 holes and 2 cases of plate with 7 holes. The average number of screws at proximal fragement was 2.5 and at distal fragment was 3.5. In 14 cases (60.8 %), we needed re-bending of plate because the distance between plate and lateral cortical margin of distal fibula was more than 5 mm at anteroposterior X-ray after reduction. All cases have anatomical reduction and there were no complications of wound infections. There were no complaint about hardware irritation. Conclusion: At fractures of distal fibula,preshaped LCP had a excellent stability although far cortex was not fixed with screw and bending of plate. And there are less complications of hardware irritation and wound problems. But, Some complement would be needed because there were no complete fitting between precontour of LCP and lateral cortical margin of distal fibula.

• Archives of Craniofacial Surgery
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• v.21 no.5
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• pp.276-282
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• 2020

Background: Orbital fractures are the most common pediatric facial fractures. Treatment is conservative due to the anatomical differences that make children more resilient to severe displacement or orbital volume change than adults. Although rarely, extensive fractures may result in enophthalmos, causing cosmetic problems. We aimed to establish criteria for extensive fractures that may result in enophthalmos. Methods: We retrospectively reviewed the charts of patients aged 0-15 years diagnosed with orbital fractures in our hospital from January 2010 to February 2019. Computed tomography images were used to classify the fractures into linear, trapdoor, and open-door types, and to estimate the defect size. Data on enophthalmos severity (Hertel exophthalmometry results) and fracture pattern and size at the time of injury were obtained from patients who did not undergo surgery during the follow-up and were used to identify the surgical indications for pediatric orbital fractures. Results: A total of 305 pediatric patients with pure orbital fractures were included-257 males (84.3%), 48 females (15.7%); mean age, 12.01±2.99 years. The defect size (p=0.002) and fracture type (p=0.017) were identified as the variables affecting the enophthalmometric difference between the eyes of non-operated patients. In the linear regression analysis, the variable affecting the fracture size was open-door type fracture (p<0.001). Pearson's correlation analysis demonstrated a positive correlation between the enophthalmometric difference and the bony defect size (p=0.003). Using receiver operating characteristic curve analysis, a cutoff value of 1.81 ㎠ was obtained (sensitivity, 0.543; specificity, 0.724; p=0.002). Conclusion: The incidence of enophthalmos in pediatric pure orbital fractures was found to increase with fracture size, with an even higher incidence when open-door type fracture was a cofactor. In clinical settings, pediatric orbital fractures larger than 1.81 ㎠ may be considered as extensive fractures that can result in enophthalmos and consequent cosmetic problems.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1571-1578
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• 2020

As a critical material in very/high-temperature gas-cooled reactors, graphite material directly affects the safety of the reactor core structures. Owing to the complex structures of graphite material in reactors, the material typically undergoes complex stress states. It is, therefore, necessary to study its mechanical properties, failure modes, and strength criteria under complex stress states so as to provide guidance for the core structure design. In this study, compressive failure tests were performed for graphite material under the condition of different confining pressures, and the effects of confining pressure on the triaxial compressive strength and Young's modulus of graphite material were studied. More specifically, graphite material based on the fracture surfaces and fracture angles, the graphite specimens were found to exhibit four types of failure modes, i.e., tension failure, shear-tension failure, tension-shear failure and shear failure, with increasing confining pressure. In addition, the Mohr strength envelope of the graphite material was obtained, and different strength criteria were compared. It showed that the parabolic Mohr-Coulomb criterion is more suitable for the strength evaluation for the graphite material.

• Journal of the Korean Orthopaedic Association
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• v.52 no.1
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• pp.7-14
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• 2017

Purpose: To report the clinical results from surgical treatment for clavicle shaft fracture by percutaneous intramedullary fixation with Steinmann pins. Materials and Methods: Between January 2004 and June 2014, the medical records of 135 patients who underwent percutaneous intramedullary fixation with Steinmann pins were reviewed. The mean follow-up periods were 15 months. The functional results were evaluated with The Disabilities of the Arm, Shoulder and Hand (DASH) score and Constant score. The clinical results were evaluated with the shortened length of the clavicle, length of surgical wound, operation time and Kang's criteria. Results: The mean bone union period was 11.6 weeks (8-16 weeks). The mean DASH score was 11.8. The mean Constant score was 91.2. The mean shortened length of the clavicle was less than 20 mm. The mean length of surgical wound was 1.2 cm (0.7-1.5 cm). The mean operation time was 18 minutes (10-35 minutes). Using Kang's criteria, 131 out of 135 patients (97.0%) showed good results. Complications included were 3 pin migrations and 2 non-unions. Conclusion: Percutaneous intramedullary fixation with Steinmann pins showed good results for treating clavicle shaft fracture.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.137-142
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• 2008

Purpose: To evaluate the clinical and radiographic results of the treatment of a proximal humerus fracture with a locking compression plate(LCP). Materials and Methods: This study reviewed the results of 24 cases of a proximal humerus fracture treated with a LCP from January 2005 to April 2007, after a follow up of more than 12 months. There were 8 males and 16 females with a mean age of 68.9(33-90) years. The clinical results were evaluated using the Neer's evaluation criteria, and the radiographic results were evaluated using the bone union time and Paavoleinen method. Results: The mean time for bone union was 11.9 weeks. Using the Neer's functional evaluation, 21 cases of the 24 patients (87%) showed excellent or satisfactory results. Twenty two cases (91%) showed good results according to the Paavoleinen method. The complications encountered were metal failure (1 patient), AVN of the humeral head (1 patient) and joint stiffness (1 patient). Conclusion: The LCP demonstrated good results in the treatment of a proximal humerus fracture and has relatively fewer complications than other internal fixators.

• Journal of Trauma and Injury
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• v.29 no.4
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• pp.105-115
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• 2016

Purpose: While all midshaft clavicle fractures have traditionally been treated with conservative measures, recent operative treatment of displaced, communited midshaft clavicle fractures has become more common. Though a recent increase in operative treatment for midshaft clavicle fractures, we have done the operative methods in limited cases. The aim of this study is to present indications, operative techniques and outcomes of the experienced cases that have applied to this limited group over the previous 10 years. Methods: This study consists of a retrospective review of radiological and clinical data from January of 2005 to July of 2015. Operative criteria for midshaft clavicle fractures having considerable risk of bone healing process were 4 groups - a floating shoulder, an open fracture, an associated neurovascular injury, and a nonunion case after previous treatment. Results: The study consisted of 18 patients who had operative treatment for midshaft clavicle fractures in adults. The most common surgical indication was a floating shoulder (10 cases, 55.6%), followed by nonunion (5 cases, 27.8%), an associated neurovascular injury (4 cases, 22.2%), and open fracture (3 cases, 16.7%). All cases were treated by open reduction and internal fixation in anterosuperior position with reconstruction plate or locking compression plate. Bone union was achieved in all cases except 1 case which was done bone resection due to infected nonunion. Mean bone union period was 19.5 weeks. There were no postoperative complications, but still sequelae in 4 cases of brachial plexus injury. Conclusion: We have conducted an open reduction and internal fixation by anterosuperior position for midshaft clavicle fractures in very limited surgical indications for last 10 years. Our treatment strategy for midshaft clavicle fractures showed favorable radiological results and low postoperative complications.

• Journal of Korean Neurosurgical Society
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• v.41 no.5
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• pp.291-294
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• 2007

Objective : The purpose of this retrospective clinical study was to describe a treatment for osteoporotic burst fracture in the setting of severe fractures involving fragmentation of the posterior wall and neural compromise with symptoms of cord compression. Methods : Indication for microscopic decompression and open kyphoplasty were intractable pain at the level of a known osteoporotic burst fractures involving neural compression or posterior wall fragmentation. A total of 18 patients [mean age, 74.6 years] with osteoporotic thoracolumbar burst fractures [3 males, 15 females] were included in this study. In all cases, microscopic decompressive laminectomy was followed by open kyphoplasty. Clinical outcome using VAS score and modified MacNab's grade was assessed on last clinical follow up [mean 6.7 months]. Radiological analysis of sagittal alignment was assessed preoperatively, immediately postoperatively, and at final follow up. Results : One level augmentation and 1.8 level microscopic decompression were performed. Mean blood loss was less than 100 ml and there were no major complications. The mean pain score before operation and at final follow up was 7.2 and 1.9, respectively. Fourteen of 18 patients were graded as excellent and good according to the modified MacNab's criteria. Overall, 6.0 degrees of sagittal correction was obtained at final follow-up. Conclusion : The combined thoracolumbar microscopic decompression and open kyphoplasty for severe osteoporotic fractures involving fragmentation of posterior wall and neural compromise provide direct visualization of neural elements, allowing safe cement augmentation of burst fractures. Decompressive surgery is possible and risk of epidural cement leakage is controlled intraoperatively.

• Journal of Korean Neurosurgical Society
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• v.45 no.1
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• pp.16-23
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• 2009

Objective : This retrospective study of 215 patients with 383 symptomatic osteoporotic vertebral compression fractures (VCFs) treated by percutaneous vertebroplasty (PVP), was performed to evaluate the clinical outcomes, and to analyze the various clinical factors affecting these results. Methods : The authors assessed the clinical outcome under the criteria such as the pain improvement, activity, requirement of analgesics, and the patient's satisfaction, and determined the relation to various peri- and intra-operative factors, and postoperative imaging findings. Results : The outcome was determined as 84.2% in relief of pain, 72.0% in change in activity, 65.7% in analgesics use, and 84.7% of satisfaction rate. More severe focal back pain, high uptake bone scan, and the lower mean T-score were related to the better pain relief following PVP. The longer the duration between fracture and PVP, the less severe focal back pain, low uptake bone scan, and leakage of PMMA into the paravertebral space were related to the less improvement in activity. Female and low uptake bone scan showed a correlation with more analgesic use. The longer the duration between fracture and PVP, low uptake bone scan, and the higher the mean T-score were correlated with the less the patients satisfaction. Conclusion : Our study suggests that PVP may be more effective in the acute phase of VCFs, more severe focal pain, and far advanced osteoporosis on BMD. Leakage of PMMA into the paravertebral spcae also could be affecting the surgical results.

• Journal of Mechanical Science and Technology
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• v.19 no.2
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• pp.634-648
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• 2005

Performed here is a comparative assessment study for the probabilistic fracture mechanics approach of the pressurized thermal shock of the reactor pressure vessel. A round robin consisting of one prerequisite deterministic study and five cases for probabilistic approaches is proposed, and all organizations interested are invited. The problems are solved by the participants and their results are compared to issue some recommendation of best practices and to assure an understanding of the key parameters in this type of approach, like transient description and frequency, material properties, defect type and distribution, fracture mechanics methodology etc., which will be useful in the justification through a probabilistic approach for the case of a plant over-passing the screening criteria. Six participants from 3 organizations responded to the problem and their results are compiled and analyzed in this study.