• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.16-25
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• 2000

The differential diffusion of two species in jet is considered. The direct photo images of $H_{2}/SF_{6}$ flame are taken and the non-react jets of $H_{2}/SF_{6}$ mixture are visualized with Rayleigh scattering method. The structures of Dual flame are found in the photography. As the volume fraction of $H_2$ in mixture is increased, the flame at side is long and as the volume fraction of $SF_{6}$ in mixture is increased, the flame at center is long. This phenomena are deduced from the non-react mixture using Rayleigh scattering method. Result show that the volume fraction in the mixture is important in differential diffusion.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.561-564
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• 2006

The tensile characteristics of four types GFRP (glass fiber reinforced polymer) reinforcing bars with different resin mix proportions and fiber volume fraction were analyzed experimentally. Four types of GFRP reinforcing bars containing approximately 66 or 70% fiber volume fraction with A or B rein mix proportions were considered in this test. All testing procedures including specimens preparation, set-up of test equipments and measuring devices were made according to the recommendations of CSA Standard S806-02. From the test results, it was found that GFRP reinforcing bars containing approximately 70% fiber volume fraction with A rein mix proportion showed the higher tensile strength than that of the others due to the higher fiber volume fraction and proper resin mix proportion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.533-538
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• 2000

Ductile fracture of dual phase steel begins with void nucleation, at martensite-ferrite interface of deformed martensite particle. In this study, void nucleation, growth, and coalescence under various strain were studied in dual phase steel. Therefore, by means of the heat treatment of low carbon steel, the study deals with void nucleation and growth for ferrite grain size and martensite volume fraction of dual phase steel using statistical method. Void nucleation and growth with increasing strain are shown depend upon the ferrite grain size. Voids volume fraction generally increase as ferrite grain size decease.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1115-1122
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• 2000

This paper addresses an application of a fiber volume fraction gradients to reduce the interlaminar forces of fiber reinforced composites subjected to thermal loadings. The degree of the reduction in the interlaminar forces may be expressed by introducing a new parameter, so called, the interlaminar force parameter. Several cases of stacking sequences and models for fiber volume fraction gradients prove the availability of the new parameter which is defined in this study.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.3
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• pp.378-386
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• 2009

The effect of fuel mixing on soot structure with methane, ethane, and propane to ethylene-base counterflow diffusion flames has been investigated by measuring the volume fraction, number density, and particle size of soot by adopting the light extinction/scattering techniques. The experimental result showed that the mixing of ethane and propane in ethylene diffusion flame increased soot volume fraction while the mixing of methane decreased. As compare to the ethylene-base flame, the diameters of soot particles for mixture flames are slightly smaller. While the soot number densities for the mixture flames are much higher. Thus, the increase in the soot volume fraction can be attributed to the appreciably increased soot number density by the fuel mixing.

• Progress in Superconductivity
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• v.3 no.2
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• pp.218-223
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• 2002

The void volume fraction of cables is one of the effective parameters to characterize the joints of superconducting magnet. Because electrical resistance and cooling stability in the CICC (Cable-in-Conduit Conductors) joint are governed by the void volume fraction, it should be controlled constantly in the termination of cable. The change of cross-section shape in the cable was fecund during the unidirectional compaction of terminal sleeve. The non-uniform thickness of the sleeve after compaction is expected because the loading is not taxi-symmetric, and the plastic flow is also not axi-symmetric. The CICC was compacted from 45% void volume fraction to 15% by using two-piece compaction jig, which could be pressed mini-directionally. Commercial code, ABAQUS, was used to analyze the plastic flow in the sleeve during the unidirectional compaction. The increment of radius of curvature of compaction jig could minimize the change of the deformed shape of cables. The calculated results were agreed with the experimental observations.

• Journal of Powder Materials
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• v.6 no.1
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• pp.81-87
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• 1999

Based on the pore filling theory, the microstructure evolution during liquid-phase sintering has been analyzed in terms of interrelationship between average grain size and relative density. For constant liquid volume fraction, the microsturucture trajectories reduced to a single curve in a grain size(x)-density(y) map, regardless of grain growth constant. The slope of curves in the map was inversely proportional to average pore size, while it increased fapidly with liquid volume fraction. Increase in pore volume fraction retarded the densification considerably, but showed marginal effect on the slope. The activation energy of densification was predicted to be the same as that of grain growth as long as the liquid volume fraction is constant for any temperature range studied. The present analyses on microstricture evolution may demonstrate the usefulness of pore filling theory and provide a guideline for process optimization of liquid-phase sintering.

• Steel and Composite Structures
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• v.7 no.5
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• pp.355-376
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• 2007

The purpose of this study is to predict and investigate the time-dependent creep behavior of composite materials. For this, firstly the evaluation method for the modulus of elasticity of whole fiber and matrix is presented from the limited information on fiber volume fraction using the singular value decomposition method. Then, the effects of fiber volume fraction on modulus of elasticity of GFRP are verified. Also, as a creep model, the nonlinear curve fitting method based on the Marquardt algorithm is proposed. Using the existing Findley's power creep model and the proposed creep model, the effect of fiber volume fraction on the nonlinear creep behavior of composite materials is verified. Then, for the time-dependent analysis of a composite material subjected to uniaxial tension and simple shear loadings, a user-provided subroutine UMAT is developed to run within ABAQUS. Finally, the creep behavior of center loaded beam structure is investigated using the Hermitian beam elements with shear deformation effect and with time-dependent elastic and shear moduli.

• Electrical & Electronic Materials
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• v.1 no.1
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• pp.44-53
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• 1988

In this study, PZT/PVDF composites with O-3 phase connectivity were prepared by hot pressing method, and the dielectric and piezoelectric properties as a function of PZT volume fraction were investigated. A modified cubic model was introduced to explain the influence of the PZT volume fraction on the experimentally determined dielectric constant. As A n=0.125, the measured dielectric constant values agreed with the calculated values. It was found that dielectric constant .xi.$_{33}$ and piezoelectric coefficient d$_{33}$ increased with indreasing PZT volume fraction, and hydrostatic piezoelectric figure of merit d/aub h/.g$_{h}$ was improved relative to that of the PZT single phase material.l.l.l.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.146-149
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• 2002

In this study, 2-2 type piezocomposites were made and characteristics as volume fraction of PZT were investigated. The accoustic impedance of 2-2 piezoelectric composites was linearly decreased with decreasing PZT volume fraction. when the volume fraction of PZT was 0.2 the acoustic impedance was 3.2 Mrayl. The electromechanical coupling factor was favourable in comparison with the single phase PZT, and that was about uniformed about 0.68 in the 0.2 to 0.6 of PZT volume fraction.