• Composites Research
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• v.18 no.2
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• pp.1-12
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• 2005

Fracture behaviors of single-edge-notched monolithic aluminum plates and glass fiber/aluminum laminates under tensile loadings have been studied using acoustic emission(AE) monitoring. AE signals from monolithic aluminum could beclassified into two different types. For glass fiber/aluminum laminates, AE signals with high amplitude and long duration were additionally confirmed on FFT frequency analysis, which corresponded to macrocrack propagation and/or delamination. AE source location determined by signal arrival time showed the zone of fracture. On the basis of the above AE analysis and fracture observation, characteristic features of fracture processes of single-edge-notched glass fiber/aluminum laminates were elucidated according to different fiber ply orientations and fiber/aluminum lay-up ratios.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.472-476
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• 2011

This paper presents the results of theoretical analysis and experimental test to verify the size effect on the fiber strength of filament wound pressure vessel. As a test method, a series of fully scaled hoop ring tests with filament wound carbon fiber-epoxy has been conducted. Test results showed remarkable size effect on fiber strength. And, as an analytical method, the WWLM(Weibull weakest link model) and SMFM(sequential multi-step failure model) were considered and compared to hoop ring test data. The analysis results showed significantly lower fiber strength value than that of test data. Through the modification of length size effect, modified SMFM is suggested. The fiber strengths from modified SMFM showed good agreement with test data.

• Journal of the Korean Society for Railway
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• v.7 no.4
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• pp.319-325
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• 2004

In this study, analysis and design programs of bending of RC beams strengthened with fiber sheets are developed by using Visual Basic Language. The program consists two groups, ultimate strength method and nonlinear flexural analysis method. Ultimate strength method regards concrete compressive stress as a rectangular stress block and do not consider tensile stress of concrete and load-deflection curves. On the other hand, nonlinear flexural analysis considers tensile stress of concrete, load-deflection curves, state of stress distribution and failure strain of strengthening material. Also, the analysis method used in this study regards nonlinear flexural stress as compressive stress of concrete. This program can be a good tool for determining the bending strength of strengthened RC beams and estimating the amount of fiber sheets for practical use.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.75-80
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• 2017

The use of optical fiber makes it possible to transfer a large amount of data, thereby enabling a high-speed image transmission with a high response speed and a large number of frames. The need for an optical fiber HDMI System has grown in importance due to the rapid development of displays with large sizes and high-resolution images. In this paper, we have studied the structural design and FEM analysis of a 4C fiber guide for hybrid interconnection implementation. According to the structural analysis of the fiber guide, we have confirmed the safety of the design and we will make additional design changes to minimize the optical loss and fabricate a fiber guide for photoelectric composite HDMI in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.157-163
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• 2018

This study is aimed at controlling the fiber orientation and improve the fiber distribution in fiber-reinforced cement composites using blades that can be placed inside the existing nozzles. To optimize the blade parameters, multi-physics finite element analysis was performed that could account for the flow of the cementitious matrix material, the movement of the entrained fibers, and the interactions with the nozzle. As a result, this study defined the blade distance, length, and position as a function of the fiber length to be used in the field. The blades with a distance from 1.2 to 2.4 times the fiber length and length from 4 to 8 times the fiber length, as well as located at below 14 times the fzfiber length from the nozzle exit maintained the fiber orientation angle less than $5^{\circ}$. In addition, the blade-type nozzle proposed in the study can be attachable and detachable to the conventional casting equipment, and thus it can provide the usability and convenience in practical applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.349-352
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• 2001

The transient response in TDFA(Thulium-Doped Fiber Amplifier) is theoretically investigated. The TDFA has the spectral gain band in 1.47 ${\mu}{\textrm}{m}$. The transient model includes the transient buildup of the population inversion, the pump power, the signal power and their transient variation along the fiber amplifier. The results of numerical analysis can predict the gain saturation and recovery time at the fiber amplifier. It also shows the gain saturation and recovery effect depending on the pumping and saturation rate.

• Composites Research
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• v.31 no.5
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• pp.251-259
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• 2018

In this paper, statistical volume element modeling method was developed for multi-scale progressive failure analysis of fiber reinforced composite materials. Big-size statistical volume elements (BSVEs) was considered to minimize the size effect in the micro-scale, by including as many fibers as possible. For that purpose, a mesh cutting method is suggested and adapted into the fiber model generator that creates finite element domain rapidly. The fiber defect model was also developed based on the experimental distribution of the fiber strength. The size effects from the local load sharing (LLS) are evaluated by increasing the fiber inclusion in the micro-scale model. Finally, continuum damage mechanics (CDM) model to the fiber direction was extracted from numerical analysis on BSVEs. And it was compared with strength prediction from typical representative volume element (RVE) model.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.237-248
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• 2011

Tensile softening characteristics play an important role in the structural behavior of steel fiber-reinforced ultra high performance concrete. Tension softening modeling and numerical analysis method are necessary for the prediction of structural performance of steel fiber-reinforced concrete. The numerical method to predict the flexural behavior is proposed in this study. Tension softening modeling is carried out by using crack equation based on fictitious crack and inverse analysis in which load-crack opening displacement relationship is considered. Thereafter material modeling is performed considering tension softening. The comparison of moment-curvature curves of the numerical analysis results with the test results indicates a reasonable agreement. Therefore, the present numerical results prove that good prediction of flexural behavior of steel fiber-reinforced ultra high performance concrete beams can be achieved by employing the proposed method.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.562-568
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• 1999

The model using homogenization technique based on energy concept for the prediction of the failure criterion of staple fiber mixed soil was developed to increase the practice and the application of staple fiber as a reinforcement for improving soft ground and agrictural structures. Parameters of the model are aspect ration and volumetric ocntnet of fiber, cohesion and internal friction angle of soil, adhesiion intercept of soil and fiber. It is judged that the model developed in this study is applicable to the soil composed of clay, silt and sand mixed by linear types of fiber such as steel bar, steel fiber , natural fiber etc..

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.2
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• pp.86-92
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• 2000

The model using homogenization technique based on energy concept for the prediction of the failure criterion of staple fiber mixed soil was developed to increase the practice and the application of staple fiber as a reinforcement for improving soft ground. Parameters of the model are aspect ratio and volumetric content of fiber, cohesion and internal friction angle of soil, adhesion intercept and interface friction angle of soil and fiber. It is considered that the model developed in this study is applicable to the soil composed of clay, silt and sand mixed by thread types of fiber such as steel bar, steel fiber, natural fiber etc.