• Journal of Power System Engineering
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• v.18 no.6
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• pp.166-173
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• 2014

In this study, a laminated composite material with dispersing aluminum oxide powder between the CFRP laminate plies, and also CFRP composites without aluminium oxide powder were fabricated for Mode I experiments using the DCB specimen and a tensile test. The behavior of the crack and the change of the interfacial fracture toughness were evaluated. Also in order to evaluate the damage mechanism for the crack extension, the AE sensor on the surface of the DCB test specimen was attached. AE amplitude was estimated for CFRP-alumina and CFRP composite. And the fracture toughness was evaluated by the stress intensity factor and energy release rate. The results showed that an unstable crack was propagated rapidly in CFRP composite specimen along with the interface, but crack propagation in CFRP-alumina specimen was relatively stable. From results, we show that aluminium oxide powder spreaded uniformly in the interface of the CFRP laminate carried out the role for preventing the sudden crack growth.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.3
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• pp.182-187
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• 2022

Superolateral dislocation of the condyle is a rare mandibular fracture. The treatment goal is to return the dislocated condyle to its original position to recover normal function. This study reports on superolateral dislocation of the condyle with mandibular body fracture. The mandibular body was completely separated, and the medial pole of the condyle head was fractured. The condyle segment was unstable and easily dislocated after reduction. The temporalis muscle on the condyle segment might have affected the dislocation of the condyle. A coronoidectomy was performed to disrupt the function of the temporalis muscle on the condyle segment in order to successfully reduce the dislocated condyle. Coronoidectomy is a simple procedure with minimal complications. We successfully performed a coronoidectomy to reduce the superolateral displaced condyle to its original position to achieve normal function. Coronoidectomy can be effectively used for reduction of superolaterally displaced condyles combined with severe maxilla-mandibular fractures.

• Journal of Korean Neurosurgical Society
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• v.59 no.2
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• pp.122-128
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• 2016

Objective : To illustrate the technique of single-stage posterior subtotal corpectomy and circumferential reconstruction for the treatment of unstable thoracolumbar burst fractures and to evaluate the radiographical and clinical outcomes of patients treated using this technique. Methods : 16 consecutive patients with unstable thoracolumbar burst fractures were treated with single-stage posterior subtotal corpectomy and circumferential reconstruction. The mean patient age was 54.8 years. The mean follower up period was 25 months. Five patients suffered from T12 fractures, 10 from L1, 1 from L2. The segmental kyphosis, neurologic status, visual analogue scale for back pain was evaluated before surgery and at follow up. Results : The segmental kyphotic angle improved from 18.5 degrees before surgery to -9.2 degrees at the last follow up. The mean correction angle was 28.9 degrees. The mean surgical time was 255 minutes, and a mean intraoperative blood loss was 1073 mL. Intraoperative complications included two dural tears, and a superficial wound infection. There were no other severe complications. The mean visual analog scale of back pain decreased from a mean value of 6.6 to 2 at the last follow up. Conclusion : The single-stage posterior subtotal corpectomy and circumferential reconstruction achieved satisfactory kyphosis correction with direct visualization of the circumferentially decompressed spinal cord, as well as good fusion with less blood loss and complications. It is a safe and reliable surgical treatment option for unstable thoracolumbar burst fractures.

• Journal of Korean Neurosurgical Society
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• v.40 no.4
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• pp.249-255
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• 2006

Objective : This study is to evaluate the efficacy of dorsal short-segment fixation in unstable thoracolumbar junction fractures. Methods : The cases of 20 patients who underwent dorsal short-segment fixation were reviewed retrospectively. Clinical outcomes were analysed using Sonntag's pain level, work status, and neurological scale according to the modified Frankel classification. Radiological outcomes were analysed using Mumford's anterior body compression[%], canal compromise ratio, and Cobb's kyphotic angle. Results : At the latest clinical follow-up [average=14.6 months]. there were 19 [95.0%] in group I and 1 patient [5.0%] in II in pain level. The postoperative work status were 17 [85.0%] in group I, 2 patients [10.0%] in II, and 1 patient [5.0%] in V. Surgery brought to improve the neurologic status. In success group [19 cases, 95%], the average canal compromise ratio was reduced from 0.57 [${\pm}0.07$] to 0.05 [${\pm}0.08$] [P<005], the average anterior body compression [%] was reduced from 41% [${\pm}17$] to 18% [${\pm}14$] [P<0.05], and the average preoperative kyphotic angle was $20.0^{\circ}$ [${\pm}9.0$], and corrected to $5.7^{\circ}$ [${\pm}7.1$] postoperatively, and progressed to $7.8^{\circ}$ [${\pm}6.2$] at the latest follow-up. There was a case of implantation failure in an elderly osteoporotic patient. Conclusion : Although there are limitations in the patient number and follow-up period, the present study favors dorsal short-segment fixation for selective cases in unstable thoracolumbar junction fractures.

• Clinics in Shoulder and Elbow
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• v.22 no.1
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• pp.29-36
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• 2019

Background: The execution of fibular allograft augmentation in unstable proximal humerus fractures (PHFs) was technically demanding. In this study, the authors evaluated the clinical and radiographic outcomes after tricortical iliac allograft (TIA) augmentation in PHFs. Methods: We retrospectively assessed 38 PHF patients treated with locking-plate fixation and TIA augmentation. Insertion of a TIA was indicated when an unstable PHF showed a large cavitary defect and poor medial column support after open reduction, regardless of the presence of medial cortical comminution in preoperative images. Radiographic imaging parameters (humeral head height, HHH; humeral neck-shaft angle, HNSA; head mediolateral offset, HMLO; and status of the union), Constant score, and range of motion were evaluated. Patients were grouped according to whether the medial column support after open reduction was poor or not (groups A and B, respectively); clinical outcomes were compared for all parameters. Results: All fractures healed radiologically (average duration to complete union, 5.8 months). At final evaluation, the average Constant score was 73 points and the mean active forward flexion was $148^{\circ}$. Based on the Paavolainen assessment method, 33 patients had good results and 5 patients showed fair results. The mean loss of reduction was 1.32 mm in HHH and 5.02% in HMLO. None of the parameters evaluated showed a statistically significant difference between the two groups (poor and not poor medial column support). Conclusions: In unstable PHFs, TIA augmentation can provide good clinical and radiological results when there are poor medial column support and a large cavitary defect after open reduction.

• Composites Research
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• v.16 no.4
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• pp.44-50
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• 2003

The damage zone around a crack tip occurring before the fracture is a significant domain. which affects the toughening mechanism of materials. In this study. the growth process of damage zone in the vicinity of crack tip for rubber-modified epoxy resin is investigated using an acoustic emission(AE) analysis. The weight fractions of rubber(CTBN 1300$\times$B) in rubber-modified epoxy resin are 5 wt% and 15 wt%. The fracture toughness($K_{IC}$) and the fracture energy($G_{IC}$) were measured using 3 point bending single-edge notched specimens. The damage zone and rubber particles distributed around the crack tip were observed by a polarized optical microscope and an atomic force microscope(AFM). The damage zone around crack tip of rubber-modified epoxy resin was formed at 13 % loading and developed until 57 % loading of the fracture load. The crack initiated at 57 % loading grew repeatedly in the stick-slip propagation behavior. Based on time-frequency analysis, it was confirmed that AE signals with frequency bands of 0.15~0.20 MHz and 0.20~0.30 MHz were generated from cavitation and stable/unstable cracking inside the damage zone.

• Journal of Welding and Joining
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• v.33 no.1
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• pp.35-40
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• 2015

Recently, there have been the increase of ship size and the development of oil and gas in arctic region. These trends have led to the requirements such as high strength, good toughness at low temperature and good weldability for prevent of brittle fracture at service temperature. There has been the key issue of crack arrestability in large size structure such as container ship. In this report for the first time, crack arrest toughness of thick steel plate welds was evaluated by large scale ESSO test for estimate of brittle crack arrestability in thick steel plate. For large structures using thick steel plates, fracture toughness of welded joint is an important factor to obtain structural integrity. In general, there are two kinds of design concepts based on fracture toughness: crack initiation and crack arrest. So far, when steel structures such as buildings, bridges and ships were manufactured using thick steel plates (max. 80~100mm in thickness), they had to be designed in order to avoid crack initiation, especially in welded joint. However, crack arrest design has been considered as a second line of defense and applied to limited industries like pipelines and nuclear power plants. Although welded joint is the weakest part to brittle fracture, there are few results to investigate crack arrest toughness of welded joint. In this study, brittle crack arrest designs were developed for hatch side coaming of large container ships using arrest weld, hole, and insert technology.

• Journal of Trauma and Injury
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• v.36 no.4
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• pp.362-368
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• 2023

Purpose: Clinical reports on treatment outcomes of sternal fractures are lacking. This study details the clinical features, treatment approaches, and outcomes related to traumatic sternal fractures over a 10-year period at a single institution. Methods: A retrospective cohort study was conducted of patients admitted to a regional trauma center between January 2012 and December 2021. Among 7,918 patients with chest injuries, 266 were diagnosed with traumatic sternal fractures. Patient data were collected, including demographics, injury mechanisms, severity, associated injuries, sternal fracture characteristics, hospital stay duration, mortality, respiratory complications, and surgical details. Surgical indications encompassed emergency cases involving intrathoracic injuries, unstable fractures, severe dislocations, flail chest, malunion, and persistent high-grade pain. Results: Of 266 patients with traumatic sternal fractures, 260 were included; 98 underwent surgical treatment for sternal fractures, while 162 were managed conservatively. Surgical indications ranged from intrathoracic organ or blood vessel injuries necessitating thoracotomy to unstable fractures with severe dislocations. Factors influencing surgical treatment included flail motion and rib fracture. The median length of intensive care unit stay was 5.4 days (interquartile range [IQR], 1.5-18.0 days) for the nonsurgery group and 8.6 days (IQR, 3.3-23.6 days) for the surgery group. The median length of hospital stay was 20.9 days (IQR, 9.3-48.3 days) for the nonsurgery group and 27.5 days (IQR, 17.0 to 58.0 days) for the surgery group. The between-group differences were not statistically significant. Surgical interventions were successful, with stable bone union and minimal complications. Flail motion in the presence of rib fracture was a crucial consideration for surgical intervention. Conclusions: Surgical treatment recommendations for sternal fractures vary based on flail chest presence, displacement degree, and rib fracture. Surgery is recommended for patients with offset-type sternal fractures with rib and segmental sternal fractures. Surgical intervention led to stable bone union and minimal complications.

• Journal of the Korean Orthopaedic Association
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• v.52 no.1
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• pp.25-32
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• 2017

Purpose: The purpose of this study was to analyze the radiological and clinical outcomes in elderly patients with unstable intertrochanteric femur fractures in accordance with the length of intramedullary nail. Materials and Methods: Between August 2009 and December 2014, a total of 139 patients-older than 65 years of age with AO/OTA classification of 31-A2 unstable intertrochanteric femur fracture-who has been followed-up for at least 1 year after the treatment with internal fixation by using an intramedullary nail were enrolled for this retrospective control study. The subjects were classified into two groups according to the length of intramedullary nail: 106 patients in the short group (group I) and 33 patients in the long group (group II). For radiological assessments, the reduction state, time to union, and implant related complications were examined. The clinical outcomes were assessed by preoperative hemoglobin, operating time, intraoperative bleeding amount, blood transfusion rate, hospitalization period, and Charnley hip pain scoring system at the final follow-up. Results: The postoperative radiographs showed good or acceptable reduction in all cases. The mean time of radiologic bone union was 4.8 months, and there was no difference between the two groups. With respect to surgical time, the group II was found to take longer (57.87 minutes) than the group I (45.65 minutes) (p=0.003). The bleeding amount during surgery of the group II was greater (288.78 ml) than that of the group I (209.90 ml) (p=0.046). The clinical results at the final follow-up were found to be satisfactory in both groups. Conclusion: In cases of good reduction of the fracture from the treatment of unstable intertrochanteric femur fracture accompanying the posteromedial fragment in elderly patients, both groups-long and short intramedullary nails-showed satisfactory radiological and clinical outcomes.

• Archives of Plastic Surgery
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• v.34 no.6
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• pp.813-817
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• 2007

Purpose: The zygomatic arch is a key element which composes the facial contour. In many cases of zygomatic arch fracture, it is difficult to fix rigidly the fractured segments. If reduced bone segments were not fixed rigidly, they are proven to be displaced by mastication or unintentional external forces. So, unfixed zygomatic arch fracture after reduction may require a external device of prevention of collapse. We introduce a new protector which stabilizing the fractured segments to prevent for collapse of the reduced zygomatic arch fracture. Methods: After reduction of zygomatic arch with blind approach(Gillies', Dingman or Keen's approach), bone segments was pulled with percutaneous traction suture in medial aspect of zygomatic arch. Then, the suture was fixed with Aqua $splint^{(R)}$, externally. And intraoperative and postoperative X-ray was done. The splint was removed on 14 days after the operation. Results: 5 patients were treated with this method. 4 patients of total patients had no collapse in zygomatic arch. There was minimal collapse in one patient. Postoperative complications such as facial nerve injury, mouth opening difficulty, contour deformity, infection, scar were not observed. Conclusion: In comparison with other techniques, this technique has several advantages which are simple and easy method, short operation time, no scar, less soft tissue injury, and facilitated removal of splint. Therefore, Aqua $splint^{(R)}$ would be a good alternative to prevent for collapse in unstable zygomatic arch fractures