• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.2 s.48
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• pp.11-19
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• 2006

In this paper the seismic performances of 4, 10, and 30-story staggered truss systems (STS) were evaluated by observing the force-displacement relationship up io failure. The results were compared with the seismic performance of conventional moment resisting frames and braced frames. According to the analysis results, the STS showed relatively satisfactory lateral load resisting capability. However, in the mid- to high-rise STS, plastic hinges formed first at the chords were transferred to vertical members of the vierendeel panels, which formed a week link and subsequently leaded to brittle collapse of the structure. Therefore to enhance the ductility of STS it would be necessary to reinforce the vertical bracing members of the virendeel panels so that the plastic hinges, once toned in cord members of a virendeel panel, spread out to virendeel panels of neighboring stories.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.473-480
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• 2011

Recently, the resizing algorithms based on the displacement participation factors have been developed for sizing members to satisfy stiffness criteria. It is proved that this resizing algorithms made for utilizing worker's stiffness design are practical and rational due to the simplicity and convenience of the method. The resizing algorithm can be practically and effectively applied to drift design of buildings. However, the researches on the change of inelastic behavior by the resizing algorithm has been insufficient. To identify the effect on the inelastic behavior of buildings by the resizing method, this study used the reinforced concrete shear wall-frame example. Through the application of the resizing method, the weights of shear wall in the lower class and the weights of columns and beams in the upper class increased respectively. And the initial stiffness of the building increased and the ductility of the buildings had similar with that of the initial structure.

• Journal of the Korea Concrete Institute
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• v.14 no.2
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• pp.156-163
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• 2002

Hollow core slabs generally have not been used for a bridge or a parking slab in Korea. In this study, high performance hollow core slabs, which have been the most thick one in domestic are re-designed and examined for practical use. Flexural tests were performed on four 315mm deep hollow core slabs to investigate adaptability for high vehicle live loadings and composite action with topping concrete. The precast slabs were pre-tensioned with ten strands of 1/2 inch diameter at the lower of slab and four strands of 1/2 inch diameter at the upper of slab, and cast with 80 mm deep topping concrete. Tested hollow core slabs showed ductile failure behaviors which were conformed to the current Ultimate Strength Design Method for a span of 10m up to the live load of 1,000 kgf/㎡. The rectangular md round shear cotters which were used for the composite action between precast and topping concrete, developed sufficient strengths because cracking, even micro had not been developed at the end of slabs up to the pure flexural tensile failure.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.2
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• pp.161-165
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• 2018

This report is a case of 38-year old female patient who had a chief complaint about having pronounciation disorder after going under mass excision due to mucoepidermoid carcinoma. She was referred to department of prosthodontics, Yonsei university. Palatal lift prosthesis was fabricated which was then relined with tissue conditioner. Evaluations on phonetics and swallowing were done and improvements were shown. Tissue conditioner was replaced with heat polymerizing resin and the patient was satisfied with the results of treatment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.5
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• pp.423-430
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• 2014

Noise and vibration, which occur in a pipe, are usually caused by the interaction between the turbulent flow and nearby wall. Although it can be estimated by a simple case of expanded pipes having complex turbulent flow, the radiated noise is highly dependent upon the size, shape, and thickness of the given model. In addition, the radiated noise propagates and has serious interference and destabilization effects on the surrounding systems, which can lead to fatigue fracture and failure. This study took advantage of the variety of commercial programs, such as FLUENT (flow solver), NASTRAN (dynamic motion solver of complex structures) and VIRTUAL LAB (radiated noise solver) based on the boundary element method (BEM), to understand the underlying physics of flow noise. The expanded pipe has separation and a high pressure drop because of the abrupt change in the cross-section. Based on the radiated noise calculations, the noise level was reduced to around 20 dB in the range of 100-500 Hz.

• Journal of the Korean Society for Heat Treatment
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• v.5 no.4
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• pp.209-214
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• 1992

A Study on the Interface Behavior of Aluminium Alloy Matrix Composites Reinforced with W Fiber. In this study the tungsten fiber reinforced 7072 aluminium alloy martrixcomposites were fabricated using vacuum hot press. The fiber has been aligned on the aluminium alloy sheets and these sheets were bonded with diffustion at 873K and 49Mpa. The behaviors of interface layer and mechanical properites have been investigated as a function of holding time at 873K. Several compounds were formed at the interface layer. These compounds were growing in propotion to holding time. XRD analysis showed that these compounds were $WAl_{12}$ $WAl_5$. The tensile strength decreased as the heat treatment time over 10hr gradually. The ductle fractur mode was turned to brittle mode after heat treatment.

• Journal of the Korean Geotechnical Society
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• v.21 no.2
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• pp.105-111
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• 2005

Shaking table tests are performed to investigate the seismic behavior of the batter pile and to bring up the countermeasures to improve the seismic performance of the batter pile. First of all, this study demonstrates how batter piles and vertical piles behave under static lateral loadings. Secondly, the vulnerability of batter plies under dynamic lateral loadings is demonstrated showing the axial forces and bending moments mobilized at the pile heads during shaking table tests. Thirdly, countermeasures to overcome the vulnerability of behavior piles during earthquakes are pursued. The countermeasures investigated in this study include introduction of a rubber element at the pile head and the deck plate connection, and introduction of hinge connection. Finally, the slope of batter piles which induces the minimum pile forces during the dynamic loadings are investigated and found to be 8:3 (Vertical to Horizontal).

• Journal of the Korean GEO-environmental Society
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• v.4 no.2
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• pp.27-37
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• 2003

In this research stress-strain behavior of composite geocell-soil systems under triaxial condition and the influence of strength due to the presence of geocell were studied. For the research a series of triaxial tests were carried out on sand specimens confined by flexible-walled single rubber cell. The diameter of all rubber cells placed at the center of the soil sample were 50 mm. Three rubber sizes, i.e. 35, 50 and 70 mm height, were applied to the soil specimen and the size of soil specimen was 50 mm in diameter and 100 mm in height. Three different densities of soil were used for the tests. In general, it was observed that the sand specimen develops an apparent cohesion due to the confinement by the geocell. The magnitude of this cohesion seemed to be dependent to the properties of the geocell material. The test results have shown that the geocell material for this research not only develops the apparent cohesion but also increases the angle of friction whereas geosynthetic material in the references showed only the increase of apparent cohesion. From the application of geocell-soil composites to the hyperbolic model, it was recognized that the determination of the peak strength influences the behavior of the geocell-soil composites.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.753-760
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• 2013

The hydrogen embrittlement of metallic materials is an important issue from the viewpoint of structural integrity. In this regard, the estimation of mechanical properties and fracture toughness under hydrogen conditions provides very important data. This study provides an experimental validation of the approach for simulating the small punch of Inconel 617 using finite element damage analysis, as recently proposed by the authors, and applies an inverse method for the determination of the constitutive tensile behavior of materials. The mechanical properties obtained from the inverse method are compared with those obtained from the tensile test and validated. The mechanical properties and fracture toughness are predicted by using the inverse method and finite element damage analysis.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.3
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• pp.9-21
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• 2012

Concrete filled steel tube (CFT) columns have been widely used in moment resisting frame structures both in seismic zones. This paper discusses the design of such members based on the advanced methods introduced in the 2005 AISC Specification and the 2005 Seismic Provisions. This study focuses particularly on design following both linear and nonlinear methods utilizing equivalent static and dynamic loads for low-rise moment frames. The paper begins with an examination of the significance of pseudo-elastic design interaction equations and the plastic ductility demand ratios due to combined axial compressive force and bending moment in CFT members. Based on advanced computational simulations for a series of five-story composite moment frames, this paper then investigates both building performance and new techniques to evaluate building damage during a strong earthquake. It is shown that 2D equivalent static analyses can provide good design approximations to the force distributions in moment frames subjected to large inelastic lateral loads. Dynamic analyses utilizing strong ground motions generally produce higher strength ratios than those from equivalent static analyses, but on more localized basis. In addition, ductility ratios obtained from the nonlinear dynamic analysis are sufficient to detect which CFT columns undergo significant deformations.