• Journal of the korean Society of Automotive Engineers
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• v.12 no.2
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• pp.29-42
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• 1990

Three dimensional frame structures with such nonlinearities as large displacements, medium rotations, plastic hinges and local defects are efficiently analyzed by introducing the nonlinear rotational spring. Formulations are based on the incremental updated Lagrangian descriptions and the virtual work principle, Axial displacement and twisted angle in beam elements are interpolated linearly, while bending displacements are approximated by the Hermite polynomials. The modified are length method is used as a solution method. The moment-angle of rotation relationship obtained analytically or experimentally can be easily incorporated into the solution procedure. Several examples tested show that the present method can be used efficiently in analyzing nonlinear frame structures with plastic hinges or local defect.

• International journal of steel structures
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• v.18 no.5
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• pp.1772-1783
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• 2018

Nowadays, the researches about composite structure system are being implemented in various fields, and many steel structures are designed based on that. In this study, the bending and seismic performance of the newly developed high-performance cold forming composite beam are evaluated by several experiments. As a result of the bending performance test, the bending moment of beam was increased stably depending on the depth and plate thickness of beam, and it is considered that the bending moment can be evaluated by the equation of a composite beam design. As a result of the seismic performance test, it was verified that sufficient seismic performance was obtained despite the increase of a negative moment rebar and depth of beam. In addition, the nominal bending moment has obtained the strength above the plastic bending moment, and also the plastic rotation angle has satisfied the requirement of composite intermediate moment frame.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.71-75
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• 1998

This study deals with the friction weldability of A7075-T6 having high specific strength. The friction welding conditions used are rotation speed 2000rpm, friction pressure 40MPa, friction time 1.5sec, upset pressure 40~100MPa, upset time 5sec. First, upset length was measured by displacement transducer. The plastic flow in 7075-T6 weld generates convex lens shaped resion by friction and concave lens shaped resion by axial force. Under the condition of upset pressure 85MPa, the friction welds have tensile strength of 552MPa and shear strength of 262MPa.

• Journal of Korean Society of Steel Construction
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• v.21 no.5
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• pp.483-492
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• 2009

In this study, nonlinear analysis of steel plane frame was performed using the refined plastic hinge method of advanced analysis techniques. In deterioration of stiffness in plastic zone, influences by flexural bending, residual stress, geometrical non-linearity, and semi-rigid connection are considered. And also, further reduced tangent modulus was used for geometrical non-linearity, top and seat angle were chosen for semi-rigid connection. Furthermore, 3 parameter power model was used for moment-rotation behaviour of beam to column connection. The loading conditions are combined with axial and lateral force and the inverse triangle distribution of lateral and eight type of analytical models were used in analysis. The results of analyses were compared with semi-rigid and rigid connection on behaviour of numerical analysis models. And also, the behaviors of frame with changes of semi-rigidity were analyzed by using the results obtained from MIIDAS-GENw.

• Earthquakes and Structures
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• v.8 no.5
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• pp.1191-1214
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• 2015

The Theory of Plastic Mechanism Control (TPMC) has been recently extended to the case of Eccentrically Braced Frames (EBFs) with inverted Y-scheme, i.e., EBFs with vertical links. In this paper a further validation of the design procedure, based on TPMC, is provided by means of Incremental Dynamic Analyses (IDA) pointing out the fulfilment of the design goal, i.e., the development of a pattern of yielding consistent with the collapse mechanism of global type where all the links are yielded and all the beams are yielded at their ends while all the columns and the diagonal braces remain in elastic range with the only exception of the base sections of first storey columns. In particular, a study case is designed according to both TPMC and Eurocode 8 provisions and the corresponding seismic performances are investigated by both push-over and IDA analyses. The results show the different performances obtained in terms of pattern of yielding, maximum interstorey drift, link plastic rotation demand and sharing of the seismic base shear between the moment-resisting part and the bracing part of the structural system. The seismic performance improvement obtained by means of TPMC, compared to Eurocode 8 provisions, is pointed out.

• Archives of Craniofacial Surgery
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• v.13 no.2
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• pp.130-134
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• 2012

Purpose: Brown syndrome is motility disorder of the eyeball which shows limited elevation in adduction and occurs very rarely after eye surgery. The authors have experienced a case of strabismus-like Brown syndrome combined with blepharoptosis and report this case with the review of literatures. Methods: A 28-year-old female suffered from hypotropia in the primary gaze and severe blepharoptosis with diplopia of the right eye after upper blepharoplasty. Rotation showed an inability to elevate the adducted right eye. She underwent extraocular muscle surgery about the 7 mm tucking of the right superior rectus muscle and 6 mm recession of right inferior rectus muscle. Intraoperatively, injury of the superior rectus muscle and foreign body were observed. Seven months after the extraocular surgery, the patient underwent frontalis muscle transfer on the right upper eyelid for the correction of blepharoptosis. Results: Postoperatively, the patient was orthophoric in the primary gaze, and she had improvements in the correction of blepharoptosis and eyeball movement. Conclusion: Repeated eyelid surgeries increase the risk of ocular motility disorder. Careful approach is essential for the proper treatment and successful outcome in secondary surgeries.

• Archives of Craniofacial Surgery
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• v.18 no.2
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• pp.112-116
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• 2017

The ideal scalp reconstruction involves closure of the defect with similar hair-bearing local tissue in a single step. Various reconstructions can be used including primary closure, secondary healing, skin grafts, local flaps, and microvascular tissue transfer. A 53-year-old female patient suffered glioblastoma, which had recurred for the second time. The neuro-surgeons performed radial debridement and an additional resection of the tumor, followed by reconstruction using a serratus anterior muscle flap with a split-thickness skin graft. Unfortunately, the flap became completely useless and a bilateral rotation flap was used to cover the defect. Two month later, seroma with infection was found due to recurrence of the tumor. Additional surgery was performed using multiple perforator based island flap. The patient was discharged two weeks after surgery without any complications, but two months later, the patient died. Radical surgical resection of tumor is the most important curative option, followed by functional and aesthetic reconstruction. We describe a patient with a highly malignant tumor that required multiple resections and subsequent reconstruction. Repeated recurrences of the tumor led to the failure of reconstruction and our strategy inevitably changed, from reconstruction to palliative treatment involving fast and stable wound closure for the patient's comfort.

• Geomechanics and Engineering
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• v.14 no.1
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• pp.1-8
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• 2018

This paper presents an investigation of the liquefaction characteristics and particle crushing of isotropically consolidated silica sand specimens at a wide range of confining pressures varying from 0.1 MPa to 5 MPa during undrained cyclic shearing. Different failure patterns of silica sand specimens subjected to undrained cyclic loading were seen at low and high pressures. The sudden change points with regard to the increasing double amplitude of axial strain with cycle number were identified, regardless of confining pressure. A higher cyclic stress ratio caused the specimen to liquefy at a relatively smaller cycle number, conversely producing a larger relative breakage $B_r$. The rise in confining pressure also resulted in the increasing relative breakage. At a specific cyclic stress ratio, the relative breakage and plastic work increased with the rise in the cyclic loading. Less particle crushing and plastic work consumption was observed for tests terminated after one cyclic loading. Majority of the particle crushing was produced and majority of the plastic work was consumed after the specimen passed through the phase transformation point and until reaching the failure state. The large amount of particle crushing resulted from the high-level strain induced by particle transformation and rotation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.629-635
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• 2009

In this research, KP-4, one of the plastic mold steels, was coated with the AlTiN from one layer to four layers by the PVD method in the $\Phi$ 8mm cemented carbide ball end mill. Coated KP-4 was processed with various conditions. For example, slope of $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$ the spindle rotation speed was changed from 10,000rpm to 16,000rpm, the tool feeding speed was changed from 1,300mm/min to 1,700mm/min, the depth of cut was also changed from 0.3mm to 0.9mm, and etc. Cutting component force according to the coating layer number, and surface roughness were studied. The cutting component force showed a good agreement better the up ward direction than the down ward direction under all experimental conditions. In case of the condition per the material shape, it was lessen when the tool have larger angle because the average effective diameter of the tool is larger. The surface roughness showed good condition in case of the up ward than the down ward direction. And, in the 3rd layer of AlTiN coating, it showed the most suitable condition.

• International journal of steel structures
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• v.18 no.4
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• pp.1177-1190
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• 2018

This study presents an analytical framework for estimating the thermo-mechanical behavior of a composite beam exposed to fire. The framework involves: a fire simulation from which the evolution of temperature on the structure surface is obtained; data transfer by an interface model, whereby the surface temperature is assigned to the finite element model of the structure for thermo-mechanical analysis; and nonlinear thermo-mechanical analysis for predicting the structural response under high temperatures. We use a plastic-damage model for calculating the response of concrete slabs, and propose a method to determine the stiffness degradation parameter of the plastic-damage model by a nonlinear regression of concrete cylinder test data. To validate simulation results, structural fire experiments have been performed on a real-scale steel-concrete composite beam using the fire load prescribed by ASTM E119 standard fire curve. The calculated evolution of deflection at the center of the beam shows good agreement with experimental results. The local test results as well as the effective plastic strain distribution and section rotation of the composite beam at elevated temperatures are also investigated.