• Journal of Korean Foot and Ankle Society
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• v.2 no.2
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• pp.57-63
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• 1998

Stress or march fractures among military personnel, especially recruits, has been appreciated for many years. According to the classical references, the second metatarsal was one of the first sites identified as a focus for march fractures and radiological evidence of fracture appeared as late as several weeks. The purpose of this study was to document the clinical feature of march fractures in Korean infantry soldiers. From 1997 to 1998, at one infantry medical company of OO infantry corps in Korea, 15 (19cases) patients with march fracture were detected among infantry soldiers. There were some different finding in the fracture site and its clinical features from the previous foreign reports. 1. There were pain and local swelling in all cases as clinical manifestation. By physical examination, direct point tenderness on the location of the fractured metatarsal shaft was characteristic. 2. On roentgenographic examination, cortical fissuring or break was seen one week after onset of symptoms and external callus was seen from two weeks or at the least four weeks. Oblique view was more useful than AP view in the diagnosis of march fractures. 3. The third metatarsal was the most frequently involved site(7 cases, 48%). and the second metatarsal was Jess frequent(3 cases, 20%). This difference of frequent site with previous reports might be attributed to the relatively long shaft of the third metatarsal, but should be analyzed in further study. 4. The incidence of the development of march fracture was 1 per 104 infantry soldiers.

• Journal of Korean Foot and Ankle Society
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• v.27 no.3
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• pp.87-92
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• 2023

Purpose: Concomitant ankle injuries associated with tibial shaft fractures can affect postoperative ankle joint pain and various postoperative ankle complications. This study compared the clinical outcomes between surgical treatment and conservative treatment of concomitant ankle injuries associated with tibial shaft fractures. Materials and Methods: From January 2015 to June 2020, a retrospective study was conducted on 118 tibia shaft fractures at the orthopedics department of the hospital. Associated ankle injuries were analyzed using plain radiographs, computed tomography (CT), magnetic resonance imaging (MRI), and intraoperative stress exams. The clinical outcomes were compared using the pain visual analog scale (pain VAS), American Orthopaedic Foot and Ankle Society Ankle-Hindfoot score (AOFAS score), and Karlsson-Peterson ankle score (KP score). Results: Seventy-two (61.02%) of the 118 cases were diagnosed with associated ankle injuries. Fifty-six cases underwent surgery for the ankle injury, and 16 cases underwent conservative treatment. The clinical results (according to the pain VAS score, AOFAS score, the KP score) were 1.79±1.26, 94.48±4.03, and 94.57±3.60, respectively, in the surgical treatment group, and 3.00±1.03, 91.06±3.02, and 91.25±3.31, respectively, in the conservative treatment group. Conclusion: Surgical treatment showed better clinical outcomes than conservative treatment in concomitant ankle injury in tibia fractures. Therefore, surgical treatment produces better clinical outcomes than conservative treatment in concomitant ankle injuries in tibia fractures. Hence to improve the clinical outcomes, more attention is needed on ankle joint injury in tibial shaft fractures for selecting suitable surgical treatments for those patients.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.1
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• pp.69-73
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• 2015

The study investigated effects of residual stresses and Charpy impact energy on brittle fractures of the butt weld between the valve and the piping, and of the valve body in nuclear power plants via a linear elastic fracture mechanics approach in the ASME B&PV Code, Sec.XI and finite element analysis. Weld residual stress in a butt weld between close check valve and piping, and residual stress in the valve due to casting process were assumed to be proportional to yield strength of base metal. Operating stresses in the butt weld and the valve body were calculated using approximate engineering formulae and finite element analysis, respectively. Applied stress intensity factors were calculated by assuming postulated cracks with specific sizes and then by substituting the residual stresses and the operating stresses into engineering formulae presented in the ASME B&PV Code, Sec.III. Plane strain fracture toughness was derived by using a correlation between Charpy V-notch impact energy and fracture toughness. Structural integrity of the weld and the body against brittle fracture was assessed by using the applied stress intensity factors, plane strain fracture toughness and the linear elastic fracture mechanics approach. As a result, it was identified that the structural integrity was maintained with decreasing the residual stress levels and increasing the Charpy V-notch impact energy.

• Journal of Veterinary Clinics
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• v.30 no.1
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• pp.1-4
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• 2013

The present study evaluated the systemic oxidative stress status during major orthopedic surgery in dogs. Sixteen dogs presented with various orthopedic diseases involving fractures or luxation of limbs. All patients underwent orthopedic surgery for treatment of fractures or luxation of limbs. A significant increase in the plasma total oxidant status (TOS) and oxidative stress index (OSI) levels in dogs after surgery was observed. Plasma total antioxidant status (TAS) levels were significantly decreased in dogs after surgery. The results of this study suggested that association or relationship in serum between TOS or TAS levels and redox imbalance were caused by surgical trauma in orthopedic disease conditions.

• Tunnel and Underground Space
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• v.16 no.6 s.65
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• pp.437-450
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• 2006

Failure around an underground opening is a function of in-situ stress magnitudes, intact rock strength and the distribution of fractures in the rock mass. At high in-situ stress, the failure process is 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 dies on the stress-induced damage of rock revealed its importance especially in a highly stressed regime. As the constructions of underground structures at deep depths increased, the cases of the brittle failure also increased and furthermore spalling was occurred in Korea at low depths. To improve the stability of the underground structures at highly stressed regime, the characteristics of brittle failure should be examined, but they have not yet been properly investigated. Therefore in this report the characteristics of brittle failure such as types, failure mechanism and modeling methods etc. were considered in all aspects, based on the previous researches.

• Geomechanics and Engineering
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• v.9 no.5
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• pp.645-667
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• 2015

Single treatment and staged treatments in vertical wells are widely applied in sandstone and mudstone thin interbedded (SMTI) reservoir to stimulate the reservoir. The keys and difficulties of stimulating this category of formations are to avoid hydraulic fracture propagating through the interface between shale and sand as well as control the fracture height. In this paper, the cohesive zone method was utilized to build the 3-dimensional fracture dynamic propagation model in shale and sand interbedded formation based on the cohesive damage element. Staged treatments and single treatment were simulated by single fracture propagation model and double fractures propagation model respectively. Study on the changes of fracture vicinity stress field during propagation is to compare and analyze the parameters which influence the interfacial induced stresses between two different fracturing methods. As a result, we can prejudge how difficult it is that the fracture propagates along its height direction. The induced stress increases as the pumping rate increasing and it changes as a parabolic function of the fluid viscosity. The optimized pump rate is $4.8m^3/min$ and fluid viscosity is $0.1Pa{\cdot}s$ to avoid the over extending of hydraulic fracture in height direction. The simulation outcomes were applied in the field to optimize the treatment parameters and the staged treatments was suggested to get a better production than single treatment.

• Journal of the Korean GEO-environmental Society
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• v.8 no.4
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• pp.27-39
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• 2007

This paper investigates numerically characteristics of the fluid flow in spatially correlated variable-aperture fractures under effective normal stress conditions. Spatially correlated aperture distributions are generated by using the geostaistical method (i.e. Turning Bands algorithm). In order to represent a nonlinear relationship between the effective normal stress and the fracture aperture, a simple mechanical formula is combined with a local flow model. Obtained numerical results indicate that the fluid flow is significantly affected by the geometry of aperture distribution varying according to the applied effective normal stress as well as the spatial correlation length of aperture distribution. Moreover, by using results simulated in this study, the modified Louis formula representing the relationship between the effective normal stress and the effective permeability of fracture is proposed.

• Geomechanics and Engineering
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• v.17 no.6
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• pp.535-541
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• 2019

Combining the radial well drilling and hydraulic fracturing technique, the production capacity of the reservoirs with low-permeability can be improved effectively. Due to the existence of radial holes, the stress around the well is redistributed, and the initiation and propagation of hydraulic fractures are different with those in traditional hydraulic fracturing. Therefore, it is necessary to study the influences of radial horizontal wells on hydraulic fracturing. The laboratory experiment was conducted to simulate the hydraulic fracturing on the physical model with radial holes. The experimental results showed that, compared with the borehole without radial holes, the sample with radial hole in the direction of maximum horizontal stress was fractured with significantly lower pressure. As the angle between direction of the horizontal hole and the maximum horizontal stress increased, the breakdown pressure grew. While when the radial hole was drilled towards the direction of the minimum horizontal stress, the breakdown pressure increased to that needed in the borehole without radial holes. When the angle between the radial hole and the maximum horizontal stress increase, the pressure required to propagate the fractures grew apparently, and the fracture become complex. Meanwhile, the deeper the radial hole drilled, the less the pressure was needed for fracturing.

• Geomechanics and Engineering
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• v.22 no.6
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• pp.529-540
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• 2020

Water inrush is a major hazard for mining and excavation in deep coal seams or rock masses. It can be attributed to the coalescence of rock fractures in rock mass due to the interaction of fractures, hydraulic flow and stress field. One of the key technical challenges is to understand the course and mechanism of fluid flows in rock joint networks and fracture propagation and hence to take measures to prevent the formation of water inrush channels caused by possible rock fracturing. Several case observations of fluid flowing in rock joint networks and coupled fracture propagation in underground coal roadways are shown in this paper. A number of numerical simulations were done using the recently developed flow coupling function in FRACOD which simulates explicitly the fracture initiation and propagation process. The study has demonstrated that the shortest path between the inlet and outlet in joint networks will become a larger fluid flow channel and those fractures nearest to the water source and the working faces become the main channel of water inrush. The fractures deeper into the rib are mostly caused by shearing, and slipping fractures coalesce with the joint, which connects the water source and eventually forming a water inrush channel.

• Archives of Plastic Surgery
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• v.48 no.1
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• pp.98-106
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• 2021

Background Hand fractures can be treated using various operative or nonoperative methods. When an operative technique utilizing fixation is performed, early postoperative mobilization has been advocated. We implemented a protocol involving controlled active exercise in the early postoperative period and analyzed the outcomes. Methods Patients who were diagnosed with proximal phalangeal or metacarpal fractures of the second to fifth digits were included (n=37). Minimally invasive open reduction and internal fixation procedures were performed. At 3 weeks postoperatively, controlled active exercise was initiated, with stress applied against the direction of axial loading. The exercise involved pain-free active traction in three positions (supination, neutral, and pronation) between 3 and 5 weeks postoperatively. Postoperative radiographs and range of motion (ROM) in the interphalangeal and metacarpophalangeal joints were analyzed. Results Significant improvements in ROM were found between 6 and 12 weeks for both proximal phalangeal and metacarpal fractures (P<0.05). At 12 weeks, 26 patients achieved a total ROM of more than 230° in the affected finger. Postoperative radiographic images demonstrated union of the affected proximal phalangeal and metacarpal bones at a 20-week postoperative follow-up. Conclusions Minimally invasive open reduction and internal fixation minimized periosteal and peritendinous dissection in hand fractures. Controlled active exercise utilizing pain-free active traction in three different positions resulted in early functional exercise with an acceptable ROM.