• Proceedings of the KSME Conference
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• 2002.08a
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• pp.483-486
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• 2002

Injection of microbubbles and/or polymer solution has been known to be a promising method for the reduction of frictional drag of water-borne vehicles. Naval Architects have been interested in friction drag reduction technology, since the friction drag of a commercial ship can be over $70{\%}$ of total resistance. The reduction of friction drag is also important for autonomous underwater vehicles and naval submarines to improve their durability and survivability In this study two sets of experiments were carried out for the friction drag reduction of 2-D channel wall and flat plate in the circulating water channels in Chungnam National University. Preliminary results from the experiments are presented and discussed.

• Interaction and multiscale mechanics
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• v.4 no.4
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• pp.257-271
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• 2011

The analysis of interfacial stresses in structural component has been the subject of several investigations but it still requires more effort and studies. In this study a general three-dimensional interface element has been formulated for stress and displacement analyses in the interfacial area between two adjacent plate bending element and brick element. Interface element has 16 nodes with 5 degrees of freedom (DOF) in each node adjacent to plate bending element and 3 DOF in each node adjacent to brick element. The interface element has ability to transfer three translations from each side of interface element and two rotations in the side adjacent to the plate element. Stiffness matrix of this element was formulated and implemented in three-dimensional finite element code. Application of this element to the reinforced concrete (RC) beam strengthened with fiber reinforced polymer (FRP) including variation of deflection, slip between plate and concrete, normal and shear stresses distributions in FRP plates have been verified using experimental and numerical work of strengthened RC beams carried out by some researchers. The results show that this interface element is effective and can be used for structural component with these types of interface elements.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.460-465
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• 2013

Plate-shaped inorganic particles are coated onto a stainless steel substrate by the electrophoretic deposition of a precursor slurry which includes the inorganic particles of $Al_2O_3$ and polymer resin in mixed solvents to mimic the abalone shell structure, which is a composite of plate-shaped inorganic particles and organic interlayer binding materials with a layered orientation. The process parameters of the electrophoretic deposition include the voltage, coating time, and conductivity of the substrate. In addition, the suspension parameters are the particle size, concentration, viscosity, conductivity, and stability. We prepared an organic-inorganic composite coating with a high inorganic solid content by arraying the plate-shaped $Al_2O_3$ particles and electrophoretic resin via an electrophoretic deposition method. We analyzed the effect of the slurry composition and the electrophoretic deposition process parameters on the physical, mechanical and thermal properties of the coating layer, i.e., the thickness, density, particle orientation, Young's modulus and thermogravimetric analysis results.

• Steel and Composite Structures
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• v.32 no.5
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• pp.595-610
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• 2019

This paper deals with the static and dynamic behavior of Functionally Graded Carbon Nanotubes (FG-CNT)-reinforced porous sandwich (PMPV) polymer plate. The model of nanocomposite plate is investigated within the first order shear deformation theory (FSDT). Two types of porous sandwich plates are supposed (sandwich with face sheets reinforced / homogeneous core and sandwich with homogeneous face sheets / reinforced core). Functionally graded Carbon Nanotubes (FG-CNT) and uniformly Carbon Nanotubes (UD-CNT) distributions of face sheets or core porous plates with uniaxially aligned single-walled carbon nanotubes are considered. The governing equations are derived by using Hamilton's principle. The solution for bending and vibration of such type's porous plates are obtained. The detailed mathematical derivations are provided and the solutions are compared to some cases in the literature. The effect of the several parameters of reinforced sandwich porous plates such as aspect ratios, volume fraction, types of reinforcement, number of modes and thickness of plate on the bending and vibration analyses are studied and discussed. On the question of porosity, this study found that there is a great influence of their variation on the static and vibration of porous sandwich plate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.605-606
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.925-926
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• 2009

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.39.2-39.2
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• 2009

In this work, Poly($\varepsilon$-Caprolactone)(PCL) andpoly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) mats were fabricated usingelectrospinning process. The electrospinning process is a simple and efficient method to fabricate the nanofibrous mats. PCL and PHBV is a kind of biodegradable polymer but their mechanical properties aren't good. For improving mechanical properties, PHBV mats were coated by TCP. Using PCL mats and TCP-coated PHBV composite mats, a bio-resorbablebone plate were made by pressing. Detailed micro-structural characterization was done by SEM techniques. Tensile strength and bending strength were also evaluated for mechanical properties. The cytotoxicity evaluation ofPCL/TCP-coated PHBV composite multilayer was done by MTT assay. The evidence obtained in this work implies the potential for use as a biodegradable boneplate.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.666-675
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• 2002

Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material. This paper presents a modified micro-electromechanical model and numerical analyses of piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Various concepts from different backgrounds including three-dimensional linear elastic and dielectric theories have been incorporated into the present linear piezoelectric model. The rule of mixture and the modified method to calculate effective properties of fiber composites were extended to apply to the PFPMIDE model. The new model was validated when compared with available experimental data and other analytical results. To see the structural responses of a composite plate integrated with the PFPMIDE, three-dimensional finite element formulations were derived. Numerical analyses show that the shape of the graphite/epoxy composite plate with the PFPMIDE may be controlled by judicious choice of voltages, piezoelectric fiber angles, and elastic tailoring of the composite plate.

• Structural Engineering and Mechanics
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• v.60 no.5
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• pp.829-849
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• 2016

In this paper, experimental as well as numerical analysis of Glass Fiber Reinforced Polymer (GFRP) laminated composite has been presented under ballistic impact with varying projectile nose shapes (conical, ogival and spherical) and incidence velocities. The experimental impact tests on GFRP composite plate reinforced with woven glass fiber ($0^{\circ}/90^{\circ}$)s are performed by using pneumatic gun. A three dimensional finite element model is developed in AUTODYN hydro code to validate the experimental results and to study the ballistic perforation characteristic of the target with different parametric variations. The influence of projectile nose shapes, plate thickness and incidence velocity on the variation of residual velocity, ballistic limit, contact force-time histories, energy absorption, damage pattern and damage area in the composite target have been studied. The material characterization of GFRP composite is carried out as required for the progressive damage analysis of composite. The numerical results from the present FE model in terms of residual velocity, absorbed energy, damage pattern and damage area are having close agreement with the results from the experimental impact tests.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.45-51
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• 2017

Poly(urethane acrylate) siloxane oligomers with Interpenetrating polymer netwoked nanoparticles were prepared to synthesize hard coating solution by reaction with diisocyanates. The diisocyanate combined siloxane hard coating solution showed more flexibility than the siloxane solution. In addition, diisocyanate resulted in improvement of curl property and surface hardness in the siloxane solution. Of the used diisocyanates, isophorone diisocyanate and acryloyloxy ethyl diisocyanate were good for UV hard coating solution. This effect will decrease brittleness in the siloxane solution using for plastic display plate.