• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.71-72
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• 2016

Most of studies on PC method aim at the structural analysis and development of PC members, and studies on the construction management aspect are insufficient. Therefore, this study tries to investigate 'hallow PC column composite method(HPC composite method)' from the viewpoint of construction management and analyze the construction cost of the composite method. On the assumption that each comparative method was applied to the zone, the difference in construction cost between the two methods was analyzed. As a result, HPC composite method increased the initial investment cost because of its factor technology, but reduced transport cost, lifting cost, and installation cost through lightweight columns. This study analyzed only the difference in construction cost of HPC composite method so that it has the limitation in evaluating its economy. Therefore, to evaluate the economy of HPC composite method, it is considered to research more the construction cost of HPC composite method.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.4
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• pp.10-16
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• 2012

This study presents the effectiveness of a composite structure at improving blast resistance. The proposed composite structure consists of carbon fiber reinforced polymer (CFRP) and steel layers. While CFRP layer is used for blast energy reflection due to its high strength, steel layer is used for blast energy absorption due to its high ductility. A dynamic model is used to simulate the elastoplastic behavior of the proposed composite structure subject to blast load. Considering the magnitude variations of a blast event, the probability of failure of each layer is evaluated using reliability analysis. By assigning design probability of failure of each layer in the composite structure, the thickness of layers is optimized. A case study for the design of CFRP-steel composite structure subjected to an uncertain blast event is also presented.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.180-183
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• 2009

Composite bipolar plates offer several advantages of low cost, light weight, and ease of manufacturing compared to traditional graphite plate. However, it is difficult to achieve both high electrical conductivity and high flexural strength. In this study, the hybrid carbons filled epoxy composite bipolar plates were fabricated to test electrical conductivity and flexural properties. Graphite powders were used as the main conducting filler and continuous carbon fiber fabrics were inserted to improve the mechanical properties of the composite. This hybrid composite showed improved in-plane electrical conductivity and flexural property. The moldability of the hybrid composite was also improved comparing to the continuous prepreg composite. This study suggested that the continuous carbon fiber inserted graphite/epoxy composites can be a potential candidate material to overcome the disadvantages of conventional graphite composite or continuous prepreg composite bipolar plates.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.285-291
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• 2015

In this paper, a composite material analysis program based on the finite element method(FEM) is used. The purpose of this study was to verify whether the composite material analysis program which developed as part of a project of development of softwares and educational contents for structural vibration and composite material analysis that can calculate how similar the macroscopic mechanical behavior of the composite materials actually. Because composite materials are generally anisotropic, analysis of composite laminate is used for the constitutive equations of orthotropic material. For convenience, the unit is ommited in all calculations. To verify the accuracy of the finite element method based program, the deflection and stress distribution of the simply supported composite material laminated plate subjected to a uniform load distribution is compared with exact solution. Size and properties of the composite material laminate used for analysis are fixed variables, and by changing the number of elements and the total thickness of the laminate is compared with the exact solution to the resulting value, respectively.

• Journal of Biomedical Engineering Research
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• v.18 no.1
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• pp.1-8
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• 1997

This study was performed to evaluate the effect of resin and filler type on the compressive strength of light-activated composite resins. Experimental composite resins containing either amorphous spherical silica or crushed quartz in two matrix resins of BisGMA/TEGDMA and UTMA/TEGDMA were prepared and the specimens of 3 m in diameter and 6m in length were made. Compressive test was subjected to a crosshead speed of 0.5 mm/min, and the fracture surFaces were examined by SEM. The compressive strength of UTMA-based composite resin was higher than that of BisGMA-based composite resin. The loading rate of spherical silica was higher than that of crushed silica when the size dis- tribution of fillers was same. Strength decrease of Bis-GMA-based composite resin was severer than that of UTMA-based composite resin in a $37^{\circ}$c water environment. Fracture surface showed that the composite resin failure developed along the matrix resin and the filler/resin interface region.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.63-66
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• 2004

In this study, a hybrid composite journal bearing composed of carbon fiber reinforced phenolic composite liner and metal backing was manufactured to solve the seizure problem of metallic journal bearing materials because the carbon fiber has self-lubricating ability and the phenolic resin has thermal resistance characteristics. To estimate the wear resistance of carbon fiber phenolic composite, wear tests were performed at several pressures and velocities. The oil absorption characteristics, coefficient of thermal expansion, strength and stiffness of the composite were also tested. Using the measured stiffness values, the thermal residual stresses in the composite were calculated to check the reliability of the composite journal bearing.

• Steel and Composite Structures
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• v.8 no.5
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• pp.423-438
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• 2008

This paper reports an experimental investigation of the behaviour of concrete-encased composite columns subjected to short-term axial load and biaxial bending. In the study, six square and four L-shaped cross section of both short and slender composite column specimens were constructed and tested to examine the load-deflection behaviour and to obtain load carrying capacities. The main variables in the tests were considered as eccentricity of applied axial load, concrete compressive strength, cross section, and slenderness effect. A theoretical procedure considering the nonlinear behaviour of the materials is proposed for determination of the behaviour of eccentrically loaded short and slender composite columns. Two approaches are taken into account to describe the flexural rigidity (EI) used in the analysis of slender composite columns. Observed failure mode and experimental and theoretical load-deflection behaviour of the specimens are presented in the paper. The composite column specimens and also some composite columns available in the literature have been analysed and found to be in good agreement with the test results.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.149-154
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• 2004

For a present study, we investigated fatigue behavior of cracked aluminum repaired by unidirectional graphite/epoxy composite material. Three different specimens were used in the fatigue tests: cracked aluminum, cracked aluminum repaired by graphite/epoxy composite patch, and plasma-treated aluminum repaired by graphite/epoxy composite patch. The surface of the aluminum was treated using a DC plasma. The results showed that the fatigue crack growth behavior of cracked aluminum was significantly improved by repairing the cracked area with a composite patch. Specifically, the specimen repaired by composite patch showed about 300％ more fatigue lift than the cracked aluminum. In particular, the plasma-treated aluminum repaired by composite patch showed almost 12 ％ more fatigue life than the cracked aluminum repaired by graphite/epoxy composite patch. The increased fatigue life of plasma-treated case was attributed to the surface roughness of aluminum by plasma treatment.

• Composites Research
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• v.35 no.3
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• pp.216-221
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• 2022

Recently, the worldwide demand for disposable masks has increased due to COVID-19 infections and severe air pollution. Personal masks should reduce breathe resistance while maintaining filtering performance. In this study, a solution blowing process is used to produce composite nanofiber filters to co-spin two polymers at once. The manufacture process of the various fiber diameter filter was designed, and the filtration performance and differential pressure of the prepared filter was investigated. Poly vinylidene fluoride-hexafluoropropylene (PVDF-HFP) and Polylactic acid (PLA) fibers were chosen to be entangled together in a layer with a diameter of 1.05 ㎛ and 0.33 ㎛. Composite nanofilters showed up to 87% filtration efficiency and 32 Pa differential pressure.

• Steel and Composite Structures
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• v.51 no.1
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• pp.43-51
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• 2024

In the current study, we aim to evaluate both microstructural characteristics and economic benefits of composite structures from supply chain utilizing AI-based method. In this regard, the various aspects of microstructure of composite materials along with the features of supply chain are discussed and quantified. In addition, the final economic aspects of the composite materials and are also presented. Based on available data, a designed artificial neural network is utilized for prediction of both microstructure and economical feature of the composite material. The results indicate that the supply chain could affect the microstructure of final composite materials which in turn make changes in the mechanical properties and durability of composite materials.