• Journal of the Korean Geophysical Society
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• v.2 no.4
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• pp.235-240
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• 1999

From the seismic network data of the Korea Institute of Geology, Mining & Materials during 1995-1996, we derived a composite fault-plane solution of the microearthquakes occurred in the Yangsan fault area. The composite fault-plane solution of nine events shows the orientation of fault 15 ± 3°in strike, 60 ± 8°in dip and 140°in rake or 128 ± 3°in strike, 56 ± 8°in dip and 37°in rake. The compressional axis of the stress field trends ENE to WSW, and this field suggests strike-slip motion with thrust component. The result is consistent with the 1996 Yeong-weol event and the stress field in and around the Korean Peninsula, previously reported.

• Steel and Composite Structures
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• v.39 no.5
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• pp.493-509
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• 2021

There is not enough mixed finite element method (MFEM) model developed for static and dynamic analysis of functionally graded material (FGM) beams in the literature. The main purpose of this study is to develop a reliable and efficient computational modeling using an efficient functional in MFEM for free vibration and static analysis of FGM composite beams subject to high order shear deformation effects. The modeling of material properties was performed using mixture rule and Mori-Tanaka scheme which are more realistic determination techniques. This method based on the assumption that a two phase composite material consisting of matrix reinforced by spherical particles, randomly distributed in the beam. To explain the displacement components of the shear deformation effects, it was accepted that the shear deformation effects change sinusoidal. Partial differential field equations were obtained with the help of variational methods and then these equations were transformed into a novel functional for FGM beams with the help of Gateaux differential derivative operator. Thanks to the Gateaux differential method, the compatibility of the field equations was checked, and the field equations and boundary conditions were reflected to the function. A MFEM model was developed with a total of 10 degrees of freedom to apply the obtained functional. In the numerical applications section, free vibration and flexure problems solutions of FGM composite beams were compared with those predicted by other theories to show the effects of shear deformation, thickness changing and boundary conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1101-1102
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• 2013

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.220-223
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• 2002

This paper introduces the development procedure of paddle type small-scaled composite rotor blade for helicopter hingeless rotor system. Paddle type composite blade design was done by using CORDAS program developed by KARI and dynamic analysis for hingeless hub with blade is done by using FLIGHTLAB which is commercial software for helicopter comprehensive analysis. The procedure to manufacture complicated shape of paddle type blade tip was developed and composite blades were manufactured after establishing the effective curing method. Through this research, the development technology of composite rotor blade with complex aerodynamic shape were accumulated and these will be applied to the related research field, for example, full size composite blade development, etc.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.57-60
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• 2003

This Paper contains the development procedure of Mach small-scaled composite rotor blade for helicopter articulated rotor system. This mach small-scaled composite blade design is conducted by using CORDAS program developed by KARI. The Dynamic analysis for an articulated rotor system with this blade is conducted by using FLIGHTLAB which is commercial software for helicopter analysis. Also the optimizing procedure of iterative design was described. The designed composite blades were manufactured after establishing the effective curing method. For small-scaled rotor test, strain gauges were embedded in composite blade spar to obtain bending & torsion strain value. To verify sectional properties of a blade, the bench test is accomplished. After comparing a designed data and tested data, Dynamic Calculation was repeated using tested data. Through this research, experiences of mach small-scaled composite blade development were accumulated and will be applied to the related research field.

• Korean Journal of Materials Research
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• v.34 no.2
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• pp.72-78
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• 2024

The lightweight and high strength characteristics of aluminum alloy materials make them have promising prospects in the field of construction engineering. This paper primarily focuses on aluminum alloy materials. Aluminum alloy was combined with concrete, wood and carbon fiber reinforced plastic (CFRP) cloth to create a composite column. The axial compression test was then conducted to understand the mechanical properties of different composite structures. It was found that the pure aluminum tube exhibited poor performance in the axial compression test, with an ultimate load of only 302.56 kN. However, the performance of the various composite columns showed varying degrees of improvement. With the increase of the load, the displacement and strain of each specimen rapidly increased, and after reaching the ultimate load, both load and strain gradually decreased. In comparison, the aluminum alloy-concrete composite column performed better than the aluminum alloy-wood composite column, while the aluminum alloy-wood-CFRP cloth composite column demonstrated superior performance. These results highlight excellent performance potential for aluminum alloy-wood-CFRP composite columns in practical applications.

• Macromolecular Research
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• v.12 no.6
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• pp.564-572
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• 2004

Modem applications could benefit from multifunctional materials having anisotropic optical, electrical, thermal, or mechanical properties, especially when coupled with locally controlled distribution of the directional response. Such materials are difficult to engineer by conventional methods, but the electric field-aided technology presented herein is able to locally tailor electroactive composites. Applying an electric field to a polymer in its liquid state allows the orientation of chain- or fiber-like inclusions or phases from what was originally an isotropic material. Such composites can be formed from liquid solutions, melts, or mixtures of pre-polymers and cross-linking agents. Upon curing, a 'created composite' results; it consists of these 'pseudofibers' embedded in a matrix. One can also create oriented composites from embedded spheres, flakes, or fiber-like shapes in a liquid plastic. Orientation of the externally applied electric field defines the orientation of the field-aided self-assembled composites. The strength and duration of exposure of the electric field control the degree of anisotropy created. Results of electromechanical testing of these modified materials, which are relevant to sensing and actuation applications, are presented. The materials' micro/nanostructures were analyzed using microscopy and X-ray diffraction techniques.

• Ceramist
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• v.23 no.1
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• pp.38-53
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• 2020

Magnetoelectric (ME) composites composed of magnetostrictive and piezoelectric materials derive interfacial coupling of magnetoelectric conversion between magnetic and electric properties, thus enabling to detect ultra-low magnetic field. To improve the performance of ME composite sensors, various research teams have explored adopting highly efficient magnetostrictive and piezoelectric phases, tailoring of device geometry/structure, and developing signal process technique. As a result, latest ME composites have achieved not only outstanding ME conversion coefficient but also sensing of ultra-low magnetic field below 1pT. This article reviews the recent research trend of ME composites for sensing of ultra-low magnetic field.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.21-27
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• 1998

In the case of existing in free-edge delaminations of composite laminates which are symmetry with respect to mid-plane in laminates also, in the case of asymmetry and anti-symmetry, the generalized quasi-three dimensional displacement field equations developed from quasi-three dimensional displacement field equations can be applied to solve above cases. We introduce three paramenters in this paper, which have not been used in quasi-three dimensional displacement field equations until now. To the laminate subjected to the axial extension strain $\varepsilon$0(C1) in $\chi$-direction, the bending deformation $\chi$$\chi$(C$_2$) around у-direction, the bending deformation w$\chi$(C$_4$) around z-direction and the twisting deformation $\chi$$\chi$y(C$_3$) around $\chi$-direction .The generalized quasi-three dimensional displacement field equations are able to be analyzed efectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.154-155
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• 2015

This study was to review the basic characteristics in order to evaluate field application of the emergency road repair materials for development of CAC(Calcium Aluminate Composite) usage. The experiment was conducted with two phases of field and laboratory conditions and the laboratory experiment consisted indoor and outdoor tests for compressive and flexural strength. In the result of an experiment, for the compressive strength test, the specimens that cured in the laboratory conditions were not satisfied the requirement of standards, while the specimens that cured in the field conditions were well satisfied with those. For flexural strength test, the result value was satisfied with the requirement on the standards only in outdoor curing condition of laboratory experiment. Based on these results, it is expected that the CAC can be used as an emergency road repair material for field conditions.