• Steel and Composite Structures
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• v.18 no.2
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• pp.325-344
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• 2015

Experimental tests on cellular beams with sinusoidal openings showed two main failure modes around the openings. They concern the formation of four plastic hinges and the local instability of the sinusoidal part of the opening. In parallel, numerical analysis of the sinusoidal part of the opening revealed the existence of an elastic rotational restraint between the intermediate web-post and the adjacent opening panel. The aim of the present study is to present an approach to quantify this rotational restraint. Through the response surface method, a mathematical model is proposed. It shows a great ability to predict the rotational restraint value as a function of the geometrical parameters of the opening. This model can be used to perform an extensive study with various geometrical configurations of beams with the aim to develop a reliable and realistic analytical model predicting the resistance of the sinusoidal openings.

• Steel and Composite Structures
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• v.9 no.5
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• pp.419-444
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• 2009

Flange and web local buckling in beam plastic hinge regions of steel moment frames can prevent beam-column connections from achieving adequate plastic rotations under earthquake-induced forces. Reducing the flange-web slenderness ratios (FSR/WSR) of beams is the most effective way in mitigating local member buckling as stipulated in the latest seismic design specifications. However, existing steel moment frame buildings with beams that lack the adequate slenderness ratios set forth for new buildings are vulnerable to local member buckling and thereby system-wise instability prior to reaching the required plastic rotation capacities specified for new buildings. This paper presents results from a research study investigating the cyclic behavior of steel I-beams modified by a welded haunch at the bottom flange and reinforced with glass fiber reinforced polymers at the plastic hinge region. Cantilever I-sections with a triangular haunch at the bottom flange and flange slenderness ratios higher then those stipulated in current design specifications were analyzed under reversed cyclic loading. Beam sections with different depth/width and flange/web slenderness ratios (FSR/WSR) were considered. The effect of GFRP thickness, width, and length on stabilizing plastic local buckling was investigated. The FEA results revealed that the contribution of GFRP strips to mitigation of local buckling increases with increasing depth/width ratio and decreasing FSR and WSR. Provided that the interfacial shear strength of the steel/GFRP bond surface is at least 15 MPa, GFRP reinforcement can enable deep beams with FSR of 8-9 and WSR below 55 to maintain plastic rotations in the order of 0.02 radians without experiencing any local buckling.

• Archives of Plastic Surgery
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• v.33 no.4
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• pp.485-490
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• 2006

Purpose: As the traditional treatment of the Wassel's type I or II of bifid thumb, Bilhaut-Cloquet, has always been the standard method despite several disadvantages such as tearing of the finger nail, injuries of the growth plate, joint instability, and long visible scarring. To overcome these drawbacks, we applied a modified Bilhaut-Cloquet Method. Methods: The subjects used for the this study were 10 of 20 patients evaluated. The patients underwent modified methods under every type of Wassel's classification. We designed a central wedge Zig-Zag incision and removed the nail and bony tissues in the remaining digit, but not soft tissue if possible, and transferred the ligaments, tendons, and soft tissue to the remaining thumb from the extra digit. We evaluated the patients' lack of extension, the total ROM of the MP and IP joints, the ROM of IP joints, and the lateral deviations of the reconstructed thumb. Results: The results were encouraging, with all patients showing a good functional and aesthetic outcome. Conclusion: The modified method proved a very effective procedure in the treatment of bifid thumb in all types, especially types I or II.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.36 no.5
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• pp.214-218
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• 2014

Macroglossia can create dental and skeletal instability after orthodontic treatment or orthognathic surgery for mandibular prognathism. In relevant literature, partial glossectomy is suggested for a good post-treatment prognosis. Most of the published partial glossectomy cases are two-staged surgery, because of concern about postoperative airway obstruction. As orthognathic surgical techniques and fixation method develop, however, concerns about postoperative airway obstruction have lessened. In this case, mandibular setback surgery and partial glossectomy were performed simultaneously, leading to stable recovery without any postoperative respiratory problems. After surgical technique to preserve the tongue tip, we achieved good outcomes without postoperative side effects of lingual hypoesthesia, pronunciation disorder and dyskinesia. We report this case with a literature review.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.85-87
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• 2012

We present a numerical investigation on gaseous (ethylene-air mixture) detonation in the elastoplastical metal tubes to understand the wall effects associated with the developing detonation instability. The acoustic disturbances originating from the rapidly expanding tube walls reach the detonating flame surface, thereby causing flame distortions and total energy losses. The compressible Navier-Stokes equations with equation of state for gas and elasto-plastic deformation field equations for inert tubes are solved simultaneously to understand the complex multi-material interaction in the rapidly expanding gas pipe. In order to track governing variables across the material interface, we use the hybrid particle level-set and ghost fluid methods to precisely estimate the interfacial quantities. Features observed from the deforming (thin) tube show substantially different behavior when a detonation propagates in the rigid (thick) tube with no acoustically responding wall conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.812-815
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• 2002

The shape of K-R curve for an ideally brittle material is flat because the surface energy is an unvaried material property. However, the K-R curve can take on a variety of shapes when nonlinear material behavior accompanies fracture. By the way, a general metallic material is nonlinear, structural steel is such. Therefore, the J-R curve form J-integral value instead of K parameters can be used to evaluate elastic-plastic materials with flaws in terms of ductile fracture that can be significant to design. In this paper, R-curve behaviors form K and J parameter is considered for the precise assessment of fracture analysis, in case of JS-SS400 steels.

• Steel and Composite Structures
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• v.1 no.1
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• pp.75-96
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• 2001

Actual buckling curves are always characterised by the erosion of ideal buckling curves. In case of compact sections this erosion is due to the imperfections, while for thin-walled members, a supplementary erosion is induced by the phenomenon of coupled instabilities. The ECBL approach- Erosion of Critical Bifurcation Load - represents a practical and convenient tool to characterise the instability behaviour of thin-walled members. The present state-of-art paper describes the theoretical background of this method and the applications to cold-formed steel sections in compression and bending. Special attention is paid to the evaluation methods of erosion coefficient and to their validation. The ECBL approach can be also used to the plastic-elastic interactive buckling of thin-walled members, and the paper provides significant results on this line.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.133-140
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• 1998

Material nonlinear analyses of RC(Reinforced Concrete) beams considering the tension stiffening effect and plastic hinge length have been conducted. Instead of taking the sophisticated layer approach which has some limitations in application to the large structures with many degrees of freedom. the moment-curvature relationships of RC sections previously constructed through the section analysis have been used. To reduce the numerical instability in nonlinear analysis and to remove the imprecision in calculation of ultimate resisting capacity, according to the used finite element mesh size, the tension stiffening effect and plastic hinge length have been taken into consideration. Finally, correlation studies between analytical and experimental results have been conducted with the objective to establish the validity of the proposed algorithms.

• Archives of Plastic Surgery
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• v.33 no.5
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• pp.637-642
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• 2006

Purpose: Incidence of chronic osteomyelitis in femur is lower than that of tibia due to abundantsurrounding soft tissue like muscles and subcutaneous fat. However, if the femur is infected, surgical approach would be very difficult because of surrounding soft tissue and bony defects would be getting larger due to the late detection. Chronic osteomyelitis of femur is an intractable disease with frequent recurrence and remained bone instability in spite of multiple classical operations. Methods: From August 1998 to October 2005, we had 7 cases of fibular osteocutaneous free flap to reconstruct the femur. Those were followed-up for 23 months. All 7 cases were male. 4 cases were in midshaft and the others are distal part of femur. Results: The 7 cases that had not been healed in spite of average 9.1 times previous operations were reconstructed successfully without the recurrence of chronic osteomyelitis. Continuous rehabilitation therapy and brace were very helpful for the ambulation. It took 5.6 months for complete union of bone, and 9.8 months for the ambulation. Conclusion: After wide resection, reconstruction of the femur using fibular osteocutaneous free flap guaranteed bone stability and prevented recurrence of osteomyelitis through rich blood supplying fibula and muscle. Double barrel graft of fibula would be needed in case of the sufficient strength and thickness of femur. We report the successful results of reconstruction of femur with fibular osteocutaneous free flap for chronic osteomyelitis of femur.

• Archives of Plastic Surgery
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• v.36 no.1
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• pp.56-60
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• 2009

Purpose: Palatal fracture and mandible fracture result in instability of dental arch. Because they divide the maxillary and mandibular alveolus sagittally and / or transversely and comminute the dentition, they permit rotation of dental alveolar segments and significantly increase the potential for fracture malalignment, complicating fracture treatment. Previous treatment of palatal fracture consisted of palatal splint application and rigid palatal vault stabilization. This procedure result in patient's oral discomfort and removal of palate and screw. Mandible fracture often results in malocclusion due to widening of posterior aspect of dental arch. So we introduce more simple method using intermolar traction wiring, which can protect the widening of dental arch and rotation of dental alveolar segment. Methods: Arch bar and intermolar traction wiring with wire 1 - 0, or 2 - 0 was applied. After exposure of fracture line, neutrooclusion was maintained with intermaxillary fixation. And then open reduction & internal fixation on maxillary fracture line, commonly maxillary buttress, alveolar ridge, pyriform aperture except palatal vault or mandibular fracture line. After 1 week, intermolar traction wiring was removed. We checked occlusion and postoperative radiologic finding. Results: From June of 2007 to October of 2007, 10 patient, who have maxillary fracture with palatal fracture and mandible fracture, underwent open reduction & internal fixation with intermolar traction wiring. All have satisfactory occlusion and there were no complication, like gingiva disease, mouth opening impairment and nonunion. Conclusion: The intermolar traction wiring accompany open reduction and internal fixation can be alternative method for restoration of dental arch in facial bone fracture.