• Archives of Craniofacial Surgery
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• v.10 no.1
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• pp.14-18
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• 2009

Purpose: Nasal packing materials are almost inserted at the end stage of closed reduction of nasal bone for postoperative bleeding control and stabilization of nasal bone. Conventionally, vaseline gauze was used for packing of nasal cavity. These days, Surgeons have tried to apply $Merocel^{(R)}$ into the nasal cavity more easily. It is difficult for patients to continue keeping the nasal packs for more than a week due to breathing difficulty. Moreover, nasal packing itself can also cause headache, dry mouth, stuffiness, etc. Methods: We performed a prospective study from March 1, 2008 to July 31, 2008. One hundred patients were divided into "$Merocel^{(R)}$ packing group" and "$Merocel^{(R)}$ and Airway Tube $Merocel^{(R)}$ packing group". Using two kinds of materials to each group after closed reduction, we observed and compared the amount of bleeding between two groups. We recorded patient's uncomfortable symptoms which were divided into four groups each 6, 24, 48 hours after nasal packing. Results: The result of the bleeding amount of Air Tube $Merocel^{(R)}$ group after 6 hours of nasal packing is that 3 people belong to mild group, 38 people moderate group, and 9 people severe group. After 6 hours of nasal packing, 11 patients have no complains. 16 patients were mild, 21 patients were moderate, 2 patients were severe. After 24 hours of nasal packing, no complain(18 patients), mild(24 patients), moderate(6 patients), severe(0 patient). After 48 hours of nasal packing, no complain(25 patients), mild(20 patients), moderate(5 patients), severe(0 patient). Conclusion: Regarding the amount of bleeding, there are no difference between two groups. In case of Air Tube $Merocel^{(R)}$ group, patient's discomfort is gradually improved after 24 hours of nasal packing, After 48 hours of nasal packing, most of the patients do not experience headache, dry mouth, stuffiness, etc. Therefore, Air Tube $Merocel^{(R)}$ can be useful for bleeding control. Moreover, it helps patients to breathe through nose more easily and reduce discomfort.

• Steel and Composite Structures
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• v.23 no.5
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• pp.517-527
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• 2017

In this paper, the effect of active confinement on the compressive behaviour of circular steel tube-confined concrete (STCC) and concrete-filled steel tube (CFST) columns is investigated. In STCC columns the axial load is only applied to the concrete core, while in CFST columns the load is carried by the whole composite section. A new method is introduced to apply confining pressure on fresh concrete by laterally prestressing steel tubes. In order to achieve different prestressing levels, short-term and long-term pressures are applied to the fresh concrete. Three groups of STCC and CFST specimens (passive, S-active and L-active groups) are tested under axial loads. The results including stress-strain relationships of composite column components, secant modulus of elasticity, and volumetric strain are presented and discussed. Based on the elastic-plastic theory, the behaviour of the steel tube is also analyzed during elastic, yielding, and strain hardening stages. The results show that using the proposed prestressing method can considerably improve the compressive behaviour of both STCC and CFST specimens, while increasing the prestressing level has insignificant effects. By applying prestressing, the linear range in the stress-strain curve of STCC specimens increases by almost twice as much, while the improvement is negligible in CFST specimens.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1255-1260
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• 2006

To maintain the structural integrity of steam generator tubes, 40% of wall thickness plugging criterion has been developed. The approach is for the steam generator tube with single crack, so that the interaction effect of multiple cracks can not be considered. Although, recently, several approaches have been proposed to assess the integrity of steam generator tube with two identical cracks whilst actual multiple cracks reveal more complex shape. In this paper, the coalescence pressure of steam generator tube containing multiple cracks of different length is evaluated based on the detailed 3-dimensional (3-D) elastic-plastic finite element (FE) analyses. In terms of the crack shape, two collinear axial through-wall cracks with different length were considered. Furthermore, the resulting FE coalescence pressures are compared with FE coalescence pressures and experimental results for two identical collinear axial through-wall cracks to quantify the effect of crack length ratio on failure behavior of steam generator tube with multiple cracks. Finally, based on 3-D FE results, the coalescence evaluation diagrams were proposed.

• Journal of Korean Society of Steel Construction
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• v.19 no.4
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• pp.403-411
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• 2007

CFT (Concrete filled steel tube) column has become popular for building construction due to not only its composite effect but also economic effect. However, the conventional CFT column also has its own disadvantages having plastic buckling at the end of column followed by the reduction of strength by yielding of steel tube. An experiment on TR-CFT (Transversely reinforced CFT) column are conducted for making up for conventional CFT column's disadvantages. The experiment parameters are strength of concrete, the layer numbers of carbon fiber sheet. In this study, hysteretic curve, initial stiffness, strength, plastic deformation capacity, and dissipated energy are compared and analyzed between CFT and TR-CFT columns.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.10a
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• pp.355.2-355
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• 1999

The spnng back phenomena occurring in the coiling process of a steam generator tube induces the dimensional inaccuracy and makes the coiling procedure difficult. In this research, an analytical model was developed to evaluate the amount of the spring back for SMART steam generator tubes. The model was developed on the basis of beam theory and elastic-perfectly plastic material property. This model was extended to consider the effect of plastic hardening and the effect of the tensile force on the spring back phenomena. Parametric studies were performed for various design variables of steam generator tubes in order to minimize the spring back in the design stage. A sensitivity analysis has shown that the low yield strength, the high elastic modulus, the small helix diameter, and the large tube diameter result in a small amount of the spring back. The amount of the spring back can be controlled by the selection of adequate design values in the basic design stage and reduced to an allowable limit by the application of the tensile force to the tube during the coiling process.rocess.

• Steel and Composite Structures
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• v.42 no.1
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• pp.49-57
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• 2022

This paper presents a study on the behavior of a bolted T-stub to square tube connection using Thread-fixed One-side Bolts (TOBs) through tests and numerical simulations. It outlines a research work of four connections with focus on the failure modes and strengths of the connection under tensile load. It was observed that the thread anchor failure caused by shear failure of hole threads controlled the final failure of the connection in the tests. Meanwhile, the out-of-plane deformation of tube wall resulted in the contact separation between hole threads and bolt threads, which in turn reduced the shear strength of hole threads. Finite element models (FEMs) allowing for the configuration details of the TOBs fixed connection are then developed and compared with the test results. Subsequently, the failure mechanism of hole threads and stress distribution of each component are analyzed based on FEM results. It was concluded that the ultimate strength of connection was not only concerned with the shear strength of hole threads, but also was influenced by the plastic out-of-plane deformation of tube wall. These studies lay a foundation for the establishment of suitable design methods of this type of connection.

• 대한미세수술학회:학술대회논문집
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• 1996.10a
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• pp.178-179
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• 1996

• Transactions of Materials Processing
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• v.5 no.2
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• pp.165-175
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• 1996

the process of strip twisting is practiced for the manufacture of some commercial parts such as elements for tube type line mixers. A thin metal strip with rectangular cross section is twisted thru an angle greater than 180。. Initial geometry is altered in to a complex one with dimen-sional changes. In practice several tryouts are necessary to obtain required dimensional accu-racies. A simple analysis model is proposed to predict the dimensional changes forming torque and axial force.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.208-219
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• 2000

In this study, static axial crush tests were performed with the new aluminum/GFRP hybrid tube. Glass/Epoxy prepregs were wrapped around an aluminum tube and co-cured. The failure of the hybrid tube was stable and progressive without trigger mechanism, and specific energy absorption was increased to the maximum of 33% in comparison with the aluminum tube. Effective energy absorption is possible for an inner aluminum tube because a wrapped composite tube constrains the deflection of an aluminum tube. The failure of a hybrid composite tube was stable without trigger mechanism because the inner aluminum tube could play the role of the crack initiator and controller. Mean crushing load could be calculated by modifying the plastic hinge collapse model for hybrid materials. The predicted results by this analytical model showed good agreement with the experimental results. It can be said that Aluminum/Glass-Epoxy hybrid tube is suitable for the vehicle front structure because this hybrid tube shows effective energy absorption, easy production, and simple application capability for RTM process.

• Archives of Plastic Surgery
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• v.34 no.5
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• pp.653-655
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• 2007

Purpose: The umbilicus is an important aesthetic component of the abdomen. Its absence is both cosmetically and psychologically distressing to the patient. Umbilical reconstruction should always be aimed at creating an umbilicus of sufficient depth and good morphology with less scarring. The C-V flap developed for nipple reconstruction was used in an inverted fashion in case of umbilical reconstruction. The aim of this article is to report our experience of scarred umbilical reconstruction using inverted C-V flap. Methods: A 22-year-old woman presented with contracted scar tissue in the umbilical region because she had undergone surgical correction of an umbilical hernia at 5 year of age. Pedicle of the inverted C-V flap was based cephalically. For enhancing depth of the umbilicus, three anchoring sutures to linea alba were done at both lateral and caudal aspects of the umbilical tube. Primary closures were done at donor sites of the V flaps and bolster sutures were done in the caudal direction of the inverted umbilical tube. Results: The patient was satisfied with the appearance of umbilicus. Major complications such as dehiscence, infection, and delayed healing did not occur. Conclusion: The inverted C-V flap is easy and simple technique, and it can produce a satisfactory reconstruction of umbilical structure.