• Earthquakes and Structures
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• v.5 no.6
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• pp.679-702
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• 2013

During an earthquake, soils filter and send out the shaking to the building and simultaneously it has the role of bearing the building vibrations and transmitting them back to the ground. In other words, the ground and the building interact with each other. Hence, soil-structure interaction (SSI) is a key parameter that affects the performance of buildings during the earthquakes and is worth to be taken into consideration. Columns are one of the most crucial elements in RC buildings that play an important role in stability of the building and must be able to dissipate energy under seismic loads. Recent earthquakes showed that formation of plastic hinges in columns is still possible as a result of strong ground motion, despite the application of strong column-weak beam concept, as recommended by various design codes. Energy is dissipated through the plastic deformation of specific zones at the end of a member without affecting the rest of the structure. The formation of a plastic hinge in an RC column in regions that experience inelastic actions depends on the column details as well as soil-structure interaction (SSI). In this paper, 854 different scenarios have been analyzed by inelastic time-history analyses to predict the nonlinear behavior of RC columns considering soil-structure interaction (SSI). The effects of axial load, height over depth ratio, main period of soil and structure as well as different characteristics of earthquakes, are evaluated analytically by finite element methods and the results are compared with corresponding experimental data. Findings from this study provide a simple expression to estimate plastic hinge length of RC columns including soil-structure interaction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.826-837
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• 2004

Rotational molding is a plastics processing technique that is ideally suited to producing relatively large, hollow, seamless parts which are partially or totally enclosed. Designers of plastic parts turn to rotational molding to produce small or large parts of unusual shape that cannot be produced as one piece by other processes, e.g., blow molding and thermoforming. In this paper, in order to enhance the quality of rotational molding plastic products, 1) surface features for the plastic products are characterized by using an image analysis system, 2) maximum tensile strength for the plastic products that are made of materials that consist of Samsung-Atofina R90lU, pigments and two different kinds of calcium carbonate (OMYA CaCO$_3$) is measured and compared with each other by using an Instron universal testing machine, 3) thickness for the plastic products is non-destructively measured to investigate the quality of the plastic products by using an A-scan ultrasonic tester.

• Archives of Craniofacial Surgery
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• v.11 no.2
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• pp.120-123
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• 2010

Purpose: Epinephrine itself exhibits some cardiotoxicity. However, it rarely induces cardiomyopathy when used in standard doses during surgery for local hemostasis. This paper reports a rare case of stress-induced cardiomyopathy in a young woman after the local infiltration of epinephrine. Methods: Corrective rhinoplasty was planned in a 20-year-old woman. Lidocaine mixed with epinephrine 1:100,000 was injected around the skin of the nose and nasal septum after inducing anesthesia, which resulted in sinus tachycardia and hypotension. Postoperative ECG showed a T wave inversion in the lead V2 and echocardiography revealed transient hypokinesia in the cardiac apex. Cardiac enzyme was mildly elevated. Results: Symptoms and laboratory findings improved considerably, and the patient was discharged from hospital without complications on the sixth day after surgery. Conclusion: The prognosis of catecholamine-induced cardiomyopathy is generally favorable. However, it is important to be aware of the possible adverse effects of local epinephrine infiltration. This case highlights the need for caution when using epinephrine.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1605-1614
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• 2005

For the last four decades, tension test of notched bars has been performed to investigate the effect of stress triaxiality on ductile fracture. To quantify the effect of the notch radius on stress triaxiality, the Bridgman equation is typically used. However, recent works based on detailed finite element analysis have shown that the Bridgman equation is not correct, possibly due to his assumption that strain is constant in the necked ligament. Up to present, no systematic work has been performed on fully plastic stress fields for notched bars in tension. This paper presents fully plastic results for tension of notched bars and plates in plane strain, via finite element limit analysis. The notch radius is systematically varied, covering both un-cracked and cracked cases. Comparison of plastic limit loads with existing solutions shows that existing solutions are accurate for notched plates, but not for notched bars. Accordingly new limit load solutions are given for notched bars. Variations of stress triaxiality with the notch radius and depth are also given, which again indicates that the Bridgman solution for notched bars is not correct and inaccuracy depends on the notch radius and depth.

• Journal of Ocean Engineering and Technology
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• v.8 no.1
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• pp.33-40
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• 1994

Welding of structure produces welding residual stresses which influence buckling strength, brittle fracture strength and cold crack on the weld parts. Therefore, it is very important to accurately analyze the residual stress before welding in order to guarantee the safety of weldment. If the weld length is long enough compared to the thickness and the breadth of plate, thermal and mechanical behaviors in the middle portion of the plate are assumed to be uniform along the thickness direction(z-axis). Thus, the following conditions(so-called plane deformation) can be assumed for the plate except near its end;1) distributions of stress and strain are independent on the z-axis;2) plane normal to z-axis before deformation remains plane during and after deformation. In this paper, plane-deformation thermal elasto-plastic problem is formulated by being based on the finite element method. Moreover special regards and paid to the fact that material properties in elastic and plastic region are temperature-dependence. And the method to solve the plane-deformation thermal elasto-plastic problem is shown by using the incremental technique. From the results of analysis, the characterisics of distribution of welding residual stress and plastic strain with the production mechanism are clarified.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.6
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• pp.568-576
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• 2010

It is widely known that the leak locating of underground plastic pipelines is much more difficult than that of cast iron pipelines. The precision of the leak locating depends upon the speed of leak signal and the time delay estimation between the two sensors on the pipeline. In this paper, six different windowing filters are considered to improve the time delay estimation especially for the plastic pipelines. The time delay is usually estimated from the peak time of cross-correlation functions. The filtering windows including rectangle, Roth, Wiener, SCOT, PHAT and maximum likelihood are applied to derive the generalized cross-correlation function and compared each other. Experimental results for the actual plastic underground water supply pipeline show that the introduction of the filtering windows improved the precision of time delay estimation. Some window functions provide excellent leak locating capability for the plastic pipe of 98 m long, which is less than 1 % of the pipe lengths. Also a new probabilistic approach that the combinations of all results from each filtering window is suggested for the better leak locating.

• Archives of Plastic Surgery
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• v.32 no.4
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• pp.474-478
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• 2005

Craniosynostosis is a congenital anomaly characterized by premature closure of cranial sutures. Surgical intervention should be performed during infancy. However, surgical correction of craniosynostosis remains bone defect and secondary angle occasionally. Currently, publications investigating solutions to bone defect and secondary angle created by cranioplasty are getting much interest. We have used $BoneSource^{(R)}$ which is relatively safe as an implantable substance for providing solutions for this problem. From June 2002 to January 2004, five children with craniosynostosis underwent frontocalvarial contouring using $BoneSource^{(R)}$ and concurrent cranial vault remodeling. The patient ages ranged from 8.0 months to 4.9 years(mean, 2.5 years). The quantity of $BoneSource^{(R)}$ implanted ranged from 10 to 25g, with a mean of 13g. This paper presents the first series of children treated with $BoneSource^{(R)}$ for frontocalvarial contouring in the surgical correction of craniosynostosis. No patients experienced any complications. Our results shows excellent retention of contour without causing asymmetry or irregularity. No visible evidence of interference with craniofacial growth were observed. Through our experiences, $BoneSource^{(R)}$ is found to be very useful for frontocalvarial contouring in children undergoing correction of craniosynostosis.

• Archives of Plastic Surgery
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• v.35 no.5
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• pp.539-544
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• 2008

Purpose: There have been limited reports on breast reconstruction after excision of phyllodes tumor. This paper reports four patients who had immediate reconstruction of the breast following excision of phyllodes tumor. Methods: We retrospectively reviewed the medical records of 14 patients from March 2000 to March 2008. Clinical data were analyzed including age, presenting symptoms and signs, type of surgery and metastasis. Results: The mean age was 38.6 years. The mean follow-up period was 40.6 months. Reconstruction was performed with latissimus dorsi musculocutaneous flap in 3 patients and transverse rectus abdominis musculocutaneous flap in 1 patient. Other cases were covered with skin graft or primary repair. 2 local recurrent cases were noted. Conclusion: The breast affected by phyllodes tumor must undergo complete excision. Followed by mastectomy, immediate reconstruction of breast improved cosmetic results, and allowed a wider surgical excision margin of tumor.

• Structural Engineering and Mechanics
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• v.52 no.6
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• pp.1085-1098
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• 2014

Plastic mechanism analysis of structures subjected to large deformation has long been used in order to determine collapse mechanisms of steel structures, and the energy absorbed in plastic deformation during such collapses. In this paper the technique is applied to vehicle roof structures that undergo large plastic deformation as a result of rollover crashes. The components of such roof structures are typically steel spot-welded hat-type sections. Ten different deformation mechanisms are defined from investigations of real-world rollover crashes, and an analytical technique to determine the plastic collapse load and energy absorption of such mechanisms is determined. The procedure is presented in a generic manner, such that it may be applied to any vehicle structure undergoing a rollover induced collapse. The procedure is applied to an exemplar vehicle, in order to demonstrate its application in determining the energy absorbed in the deformation of the identified collapse mechanisms. The procedure will be useful to forensic crash reconstructionists, in order to accurately determine the initial travel velocity of a vehicle that has undergone a rollover and for which the post-crash vehicle deformation is known. It may also be used to perform analytical studies of the collapse resistance of vehicle roof structures for optimisation purposes, which is also demonstrated with an analysis of the effect of varying the geometric and material properties of the roof structure components of the exemplar vehicle.

• Geomechanics and Engineering
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• v.8 no.1
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• pp.53-66
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• 2015

Plastic wastes, particularly polyethylene terephthalate (PET) generated from used bottled water constitute a worldwide environmental issue. Reusing the PET waste for geotechnical applications not only reduces environmental burdens of handling the waste, but also improves inherent engineering properties of soil. This paper investigated factors affecting shear strength improvement of PET-mixed residual soil. Four variables were considered: (i) plastic content; (ii) plastic slenderness ratio; (iii) plastic size; and (iv) soil particle size. A series of unconfined compression tests were performed to determine the optimum configurations for promoting the shear strength improvement. The results showed that the optimum slenderness ratio and PET content for shear strength improvement were 1:3 and 1.5%, respectively. Large PET pieces (i.e., $1.0cm^2$) were favorable for fine-grained residual soil, while small PET pieces (i.e., $0.5cm^2$) were favorable for coarse-grained residual soil. Higher shear strength improvement was obtained for PET-mixed coarse-grained residual soil (148%) than fine-grained residual soils (117%). The orientation of plastic pieces in soil and frictional resistance developed between soil particles and PET surface are two important factors affecting the shear strength performance of PET-mixed soil.