• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.135-142
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• 2001

This study discusses frequency analysis based on the frequency spectrum and process characterization in orthogonal cutting of Fiber-matrix composite materials. A sparsely distributed idealized composite material, namely a glass reinforced polyester(GFRP) was used as workpiece The present method employs a force sensor and the signals from the sensor are processed using the fast Fourier transform(FFT) technique. The experimental correlations between the different chip formation mechanisms and power spectrum me established. Effects of fiber orientation, cutting parameters and tool geometry on the cutting mechanisms me also discussed.

• Coupled systems mechanics
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• v.12 no.2
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• pp.151-165
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• 2023

In this study, a simple method for the determination of the shear correction factor for composites beam with a rectangular cross section is presented. The plane stress elasticity assumption is used after simplifications of the expression of the stress distribution in the beam. The different fiber orientation angle and volume fraction are considered in this work. The studied structure is subjected to various loading type (thermal and hygrothermal). The numerical results obtained show that there is a dependence of the shear coefficient on the orientation of the fibers. The evolution of the shear correction factors depends not only on the orientation of the fibers and also on the volume fraction and the environment. the advantage of this developed formula of the shear correction factor is to obtain more precise results and to consider several parameters influencing this factor which are neglected if the latter is constant.

• 한국문화재보존과학회:학술대회논문집
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• 2006.11a
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• pp.11-15
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• 2006

This work aims to clarify the character and selection of repair papers, based on fibre orientation information of paper cultural properties under restoration; using nondestructive image analysis applied to micrographs of paper surfaces. Image analysis using fast Fourier transform with suitable modifications was demonstrated to be an effective means to determine angle and intensity of fiber orientation as a nondestructive method. In the case of contemporary repair papers, the Japanese handmade paper exhibited a high anisotropy value, while the Korean handmade papers exhibited low anisotropy values. Korea and Japanese traditional hand making papers were well distinguished. Korea and Japanese papers made in the traditional ways showed its own characteristic orientation behavior in accordance with the motion of a bamboo wire.

• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.272-281
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• 1999

Cylindrical panels are widely used as aircraft fuselages and rocket etc, and the cutouts for weight reduction or wiring at such structures tend to cause the stress concentration and the local radial displacement so that seriously effect the stability of structures. In this paper, for the cylindrical composite panel with coutout at the center, the buckling and postbuckling behaviour regarding the shape and size of cutout is analyzed by finite element method. Also the lamination mechanism , changing bending stiffness and fiber orientation angle variation are researched to be regarded in studying the laminated composite materials.

• Steel and Composite Structures
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• v.29 no.5
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• pp.681-688
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• 2018

In this paper, buckling load of edge stiffened composite plates is assessed. The effect of stiffener edge size, circular hole, and the fiber orientation angle on buckling behavior of composite plates under uni-axial compressive load is investigated. This paper includes two parts as experimental and numerical studies. L-shape composite plates are manufactured in three different layups. Then the buckling loads are experimentally determined. Subsequently, by using the numerical simulation, the size variation effects of stiffener edge and circular cutout on the plate buckling loads are analyzed in five different layups. The results show that cutout size, stiffener edge height and fiber orientation angle have important effects on buckling load. In addition, there is an optimum height for stiffener edge during different conditions.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.235-240
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• 2010

The recent trend of vehicle design aims at crash safety and environmentally-friendly aspect. For the crash safety aspect, energy absorbing members should be absorbed with collision energy sufficiently. But vehicle structure must be light weight for the environmentally-friendly aspect, in order to improve fuel efficiency and to reduce tail gas emission. Therefore, the light weight of vehicle must be achieved in a status of securing safety of crash. An aluminum or CFRP (Carbon Fiber Reinforced Plastics) is representative one among the light-weight materials. In this study, impact collapse behavior of circular hybrid thin-walled member is evaluated. The hybrid members are manufactured by wrapping CFRP prepreg sheets outside the aluminum circular members in the autoclave. Because the CFRP is an anisotropic material whose mechanical properties change with its stacking condition, special attention is given to the effects of the stacking condition on the collapse behavior evaluation of the hybrid thin-walled member. Collapse mode and energy absorption capability of the hybrid thin-walled member are analyzed with change of the fiber orientation angle and interface number.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.649-654
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• 2002

In recent days the more use of CFRP composite is in the airplane, automobile, and sport goods , etc., the more necessity of research on it in this engineering. In this research, the CFRP composite specimen are fabricated by 48 CFRP plies with 8 orientation angles, and the specimens are drilled with 3 tools. The results are analyzed with consideration of cutting force, type of tools and fabrication condition. The specimens with each drilling conditions are also investigated with SEM. The optimal drilling conditions such as drill types and cutting fence with respect to the fabricating condition are studied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.960-963
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• 2002

In recent days the more use of CFRP composite is in the airplane, automobile, and sport goods, etc., the more necessity of research on it in this engineering. In this research, the CFRP composite specimen are fabricated by 48 CFRP plies with 8 orientation angles, and the specimens are drilled with 3 tools. The results are analyzed with consideration of cutting force, type of tools and fabrication condition. The specimens with each drilling conditions are also investigated with SEM. The optimal drilling conditions such as drill types and cutting force with respect to the fabricating condition are studied.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.108-113
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• 2004

The compressive axial collapse tests were performed to investigate energy absorption characteristics of Al/CFRP compound tubes which are aluminum tubes wrapped with CFRP (Carbon Fiber Reinforced Plastics) outside the aluminum circular and square tubes. Based on collapse characteristics of aluminum tubes and CFRP tubes respectively, the axial collapse tests were performed for Al/CFRP compound tubes which have different fiber orientation angles. Test results showed that Al/CFRP compound tubes supplemented the unstable brittle failure of CFRP tubes due to ductile nature of inner aluminum tubes. In the light-weight aspect, specific energy absorption were the highest for Al/CFRP, CFRP in the middle, and aluminum the lowest. Also, specific energy absorption of circular tubes was higher than square tubes'. It turned out that fiber orientation angle of Al/CFRP compound tubes influence specific energy absorption together with the collapse modes of the tubes.