• Journal of Aerospace System Engineering
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• v.3 no.2
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• pp.1-11
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• 2009

A structural modelling for study on dynamic characteristics of tapered composite aircraft wings in the form of thin-walled beam is presented. The proposed structural model includes effects of transverse shear flexibility exhibited by the advanced composite materials and warping restraint characterizing elastic anisotropy and induced structural couplings. The complex effects of these factors could have a role in more efficient analysis on those structural models.

• Journal of the Korean GEO-environmental Society
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• v.14 no.4
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• pp.59-66
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• 2013

The foundation of offshore wind energy system is generally assumed to be fixed-ended in system analysis for the convenience of calculation and, correspondingly, it might lead a conservative design. If soil-foundation interaction get involved with the analysis, the system characteristics such as natural frequency, shear force, moment and displacement are expected to differ from those of fixed-ended case. In this study, the analysis have been conducted to identify how the response of offshore wind turbine varies upon considering the foundation flexibility with soil-foundation interaction. The model taking account of the flexibility of foundation was compared with fixed-ended model at the seabed. The flexibilities of foundation were obtained by coupled spring model at the seabed and Winkler Spring Model with soil depth. As a result, the first mode of the whole system with the Winkler Spring Model was decreased relative to that with the fixed-ended model. The results showed that the effect of foundation flexibility should be considered when designing the offshore wind energy system.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.8
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• pp.883-891
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• 2003

In this study, a change of hand of fabrics dyed with persimmon juice was measured using Kawabata Evaluation System. Using various cotton fabrics, linen fabric and silk fabric used frequently for persimmon juice dyeing, we examined the changes of physical properties and hand according to persimmon juice dyeing and washing. The dynamic characteristics of hand were measured tensile, shear, bending, compression, surface properties, thickness and weight. Linearity of load-extention and tensile resilience were increased in all kinds of fabrics after dyeing. Tensile energy decreased in cotton fabric 2(gauze), cotton fabric 3(muslin) and linen fabric. Shear stiffness and hysteresis of shear increased in most of fabrics. Bending rigidity of the bending property and hysteresis of bending, linearity of compression of the compression property, compression energy and compression resilience increased in all kinds of fabrics after dyeing. Thickness and weight increased much in all kinds of fabrics after dyeing. In the primary hand value, stiffness and anti-drape stiffness increased in all kind of fabrics after dyeing. The fullness and softness, crispness, scrooping feeling and flexibility with soft feeling decreased. As the stiffness after persimmons dyeing increased, it was suitable for clothes material of summer.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.387-390
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• 2006

Conventional spinning, shear forming and flow forming techniques are being utilized increasingly due to the great flexibility provided for producing complicated parts, enabling customers to optimize designs and reduce weight and cost, all of which are vital, especially in automotive industries, space shuttle, a munitions industry. The deformation mechanism of conventional spinning and shear forming is studied in this paper through analysis. The forming loads of a spin formed dome in an Al launch vehicle fuel tank was studied analysis and a simple FE model to predict the forming loads of the dome was proposed. The analysis is carried out to study the effects of feed rates and thickness reduction on material flow.

• Structural Engineering and Mechanics
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• v.63 no.2
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• pp.237-249
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• 2017

The Self-Organization Feature Map as an unsupervised network is very widely used these days in engineering science. The applied network in this paper is the Self Organization Feature Map with constant weights which includes Kohonen Network. In this research, Reinforced Concrete Shear Wall buildings with different stories and heights are analyzed and a database consisting of measured fundamental periods and characteristics of 78 RC SW buildings is created. The input parameters of these buildings include number of stories, height, length, width, whereas the output parameter is the fundamental period. In addition, using Genetic Algorithm, the structure of the Self-Organization Feature Map algorithm is optimized with respect to the numbers of layers, numbers of nodes in hidden layers, type of transfer function and learning. Evaluation of the SOFM model was performed by comparing the obtained values to the measured values and values calculated by expressions given in building codes. Results show that the Self-Organization Feature Map, which is optimized by using Genetic Algorithm, has a higher capacity, flexibility and accuracy in predicting the fundamental period.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.97-105
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• 2006

The reinforced concrete flat plate system provides architectural flexibility, clear space, reduced building height, simple formwork, which consequently enhance constructibility. One of the serious problem in the flat plate system is brittle punching shear failure due to transfer of shear force and unbalanced moments in column-slab connection. Since the use of high strength concrete recently has become in practice for reinforced concrete structures, it is highly desired to establish the structural design method for flat plate construction using high strength concrete. In this paper, interior column-slab connection constructed with high strength concrete were tested under lateral and gravity loads to evaluate their strength and behavior. The test parameters were slab reinforcement ratio and the gravity load levels.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.421-432
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• 2009

In this study, push-out and static loading tests were conducted to evaluate the behavioral characteristics of composite beams with a perfobond rib shear connector. The shear capacity of the perfobond rib was found to be proportional to its concrete strength, which is in turn affected by the increase in the concrete end-bearing strength and concrete dowel action to resist the shear force. The relative slips of the push-out specimen, however, which was used to assess the ductility of the shear connector, increased to some extent, but it no longer increased when it reached the critical concrete strength because of the flexibility of the transverse rebar in the rib hole. The static-loading-test results revealed a crack on the concrete slab in the composite beam with a perfobond rib on the side of the rib hole and transverse rebar for the applied moment and shear force to the rib hole, depending on the static loading. The shear resistance characteristics of the perfobond rib shear connector were found to resist the shear force from the relative slip on the interface of the composite beam. Thus, the sectional effect of the shear connector to the composite beam with a perfobond rib should be considered when designing the composite beam because the behavior of the composite beam can change owing to the shear connector.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.143-153
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• 2021

The corroded pier that has corrosion of the tranverse steel, main steel and lapsplice directly affects the seismic performance. The corrosion of the tranvese and main steel directly reduce the shear strength and bendig strength. If steel corrosion occurs in lap splice, the flexural strength and flexibility of existing corroded pier that are not seismic design are significantly reduced. In addition, as the axial force acting on the pier increase the shear strength. Considering these effects. In this stuydy, we cosidered steel corrosion, lap splice and axial force, for a reasonable evaluation of seismic-performance. It is confirmed that flexular failure occurs at pies where shear failure is expected to occur due to corrosion of reinforcement. These failure modes and their reason are analyzed, and necessary considerations are presented for seismic reinforcement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.124-135
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• 2011

The capacity of bearings installed at abutments and piers for continuous bridges is usually determined by the magnitude of the maximum vertical reaction at each support and the capacity of bearings placed at piers is higher than that at abutments. In this study, the possibility of the improved seismic performance of base-isolated continuous skew bridges was investigated by analysing the variation of the seismic behavior of them according to three arrangements of bearings. Based on the conventional arrangement of bearings(Case A), three arrangements of bearings such as Case A, Case B and Case C were selected considering the variation of the horizontal stiffness of the lead rubber bearing(LRB) installed at the pier. The seismic behavior of the total 36 skew bridges was investigated by conducting the response spectrum analysis using the hybrid response spectrum considered the effect of LRB's damping. Results of analyses show that a more desirable seismic behavior of base-isolated continuous skew bridges can be obtained by reducing the magnitude of the horizontal stiffness of LRB placed at the pier to similar to or less than that of LRB installed at abutments. The variation of LRB's stiffness at the pier brings about period elongation and the change of mode shapes of base-isolated skew bridges and results in the reduction of the total base shear, the maximum base shear at the pier and the girder stresses. Although positive effects on the seismic behavior of base-isolated skew bridges caused by the change of arrangement of bearings decreased slighty with an increase in the flexibility of the substructure, the proposed arrangements of bearings bring about the improved seismic performance of base-isolated continuous skew plate girder bridges with less than 10m height of piers.

• Wind and Structures
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• v.38 no.1
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• pp.15-42
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• 2024

A flexible-base coupled-two-beam (CTB) discrete model with equivalent tuned mass dampers is used to assess the effect of soil-structure interaction (SSI) and different types of lateral resisting systems on the design of passive dynamic absorbers (PDAs) under the action of along-wind and across-wind loads due to vortex shedding. A total of five different PDAs are considered in this study: (1) tuned mass damper (TMD), (2) circular tuned sloshing damper (C-TSD), (3) rectangular tuned sloshing damper (R-TSD), (4) two-way liquid damper (TWLD) and (5) pendulum tuned mass damper (PTMD). By modifying the non-dimensional lateral stiffness ratio, the CTB model can consider lateral deformations varying from those of a flexural cantilever beam to those of a shear cantilever beam. The Monte Carlo simulation method was used to generate along-wind and across-wind loads correlated along the height of a real shear wall-frame building, which has similar fundamental periods of vibration and different modes of lateral deformation in the xz and yz planes, respectively. Ambient vibration tests were conducted on the building to identify its real lateral behavior and thus choose the most suitable parameters for the CTB model. Both alongwind and across-wind responses of the 144-meter-tall building were computed considering four soil types (hard rock, dense soil, stiff soil and soft soil) and a single PDA on its top, that is, 96 time-history analyses were carried out to assess the effect of SSI and lateral resisting system on the PDAs design. Based on the parametric analyses, the response significantly increases as the soil flexibility increases for both type of lateral wind loads, particularly for flexural-type deformations. The results show a great effectiveness of PDAs in controlling across-wind peak displacements and both along-wind and across-wind RMS accelerations, on the contrary, PDAs were ineffective in controlling along-wind peak displacements on all soil types and different kind of lateral deformation. Generally speaking, the maximum possible value of the PDA mass efficiency index increases as the soil flexibility increases, on the contrary, it decreases as the non-dimensional lateral stiffness ratio of the building increases; therefore, there is a significant increase of the vibration control effectiveness of PDAs for lateral flexural-type deformations on soft soils.