• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.52-55
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• 2002

This paper examines the effective thermal conductivity of 3-D braided glass/epoxy composites. 3-D braided composites have a number of advantage over conventional laminate composites, including through-thickness reinforcement, and high damage tolerance and processability. The thermal properties of composites depend primarily on the microstructure of the braided preform and properties of constituent materials. A thermal resistance network model based on structure of the braided preform is proposed by using thermal-electrical analogy. In order to affirm the applicability theses solutions, thermal conductivities of 3-D braided glass/epoxy composites are measured

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.5-9
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• 2002

This paper presents a method and procedure for stress analysis and sizing in development of structures of a large composite wind turbine blade. Structural requirement of IEC standard was reviewed to set up appropriate analysis method and procedure. Several structural layouts were examined in a viewpoint of a large scale wind turbine blade. For the critical load cases, stress analysis were performed using finite element method. Stacking sequence and thickness of a laminate for each part and location were determined considering stress levels and producibility. Nonlinear geometric analysis was performed to check stability problem due to local buckling of a skin structures.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.583-586
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• 2000

This work ethibits how susceptive the shear ultrasonic waves are to a little misoriented plies according to the angle variation of shear ultrasoic waves $0^\circ$ , $45^\circ$ and $90^\circ$. Also, it is shown that shear waves, particularly the transmission mode with the transmitter and receiver perpendicular to each other, have high sensitivity for detecting anomalies in fiber orientation and ply layup sequence that may occur in the manufacturing of composite laminates. Experimental results are agreed with modeling solutions which were based on decomposition of shear wave polarization vector as it propagates through the composite laminates. This wave appeared considerably to be sensitive to CFRP composites to the thickness direction along in-plane fibers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.42-45
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• 2003

The purpose of this study is the development or the extensive Rapid Prototyping Technique. which can resolve the long-term manufacturing process, shrinkage and deformation occurring rapid prototyping technique. To begin with. the various specimens for tensile were manufactured on the basis of this modeling technology. Then, many kinds of the laminate pieces for the test were made by using the sheet metals lmm and 1.5mm thickness which is composed of the same ingredient. The tensile specimen were manufactured by changing the process variables, Such as electric current, pressure and resistance welding time for the Rapid Prototyping with metal sheet. And then by using the Taguchi method. The interrelation between the specimen and mechanical properties were determined and the system for the optimum process variable organized.

• Computational Structural Engineering : An International Journal
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• v.1 no.1
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• pp.39-48
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• 2001

An analytical compressive stress-strain relationship model for circular and rectangular concrete specimens confined with laminated carbon fiber sheets (CFS) is studied. Tsai-Hill and Tsai-Wu failure criteria were used to implement orthotropic behavior of laminated composite materials. By using these criteria, an algorithm which analyzes the confinement effect of CFS on concrete was developed. The proposed analytical model was verified through the comparison with experimental data. Various parameters such as concrete strength, ply angle, laminate thickness, section shape, and ply stacking sequences were investigated. Numerical results by the proposed model effectively simulate the experimental compressive stress-strain behavior of CFS confined concrete specimens. Also, the pro-posed model estimates the compressive strength of the specimen to a high degree of accuracy.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.24-26
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• 2006

The copper foil of 10fm of thickness was prepared, and the surface treatment on the copper foil was done by the method of the electrolytic plating in the acid solution with the sulfate ion as a purpose to remove the main element of the surface contaminant of copper variously. The structure on the surface of the copper foil in this study investigated AFM with SEM the changed phenomenon according to added plating time and current. The phenomenon of the structure's of the oxide on the surface of long plating time and high current growing was confirmed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1686-1699
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• 1993

In this paper, the thermal buckling of thick composite angle-ply laminates subject to uniform temperature distribution is studied. For the plates of 4-edges simply supported condition and those of 4-edges clamped condition, the critical buckling temperatue is derived, using tile finite element method based on the shear deformation theory. The effects of lamination angle, layer number, laminate thickness, plate aspect ratio and boundary constraints upon the critical buckling temperature are presented.

• Steel and Composite Structures
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• v.28 no.3
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• pp.389-401
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• 2018

An isoparametric six-node triangular element is utilized for geometrically nonlinear analysis of functionally graded (FG) shells. To overcome the shear and membrane locking, the element is improved by using strain interpolation functions. The Total Lagrangian formulation is employed to include the large displacements and rotations. Finding the nonlinear behavior of FG shells via laminated modeling is also the goal. A power function is employed to formulate the variation of elastic modulus through the thickness of shells. The results are presented in two ways, including the general FGM formulation and the laminated modeling. The equilibrium path is obtained by using the Generalized Displacement Control Method. Some popular benchmarks, including hyperbolical shell structures are solved to declare the correctness and accuracy of proposed formulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.419-422
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• 2014

Floor impact sound level is affected by various factors. This study was examined about impact sources and floor coverings influenced at floor impact sound. So this study wishes to get method to reduce sound pressure level of receiving room. Light-weight impact sound in mid frequency and Heavy-weight impact sound in low frequency was affected by floor coverings. Therefore, method to reduce floor impact sound level is to use proper floor coverings. Some coverings can amplify the heavy-weight impact sound in low frequency. Floor impact sound sources used measurement and analysis were standard heavy-impact source(Tapping, Bang, Ball) and living impact sources(Cleaner, Chair, Toy-car, Soccer ball). And Floor coverings used measurements were various thickness vinyl, laminate(or ply-wood) floor. Especially vinyl floor coverings were very effective method to reduce floor impact.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.15-21
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• 2009

The anisotropic mechanical properties were measured for the three orthogonal orientations of plain weave glass fabric reinforced epoxy resin laminate. In tensile and flexural tests, axial and edge type specimens failed by pull-out of warp and fill yarns, respectively. In contrast, the thickness type specimens failed by adhesive failure process. Longitudinal cracking occurred in several of the edge type specimens during tensile test. That cracking caused pop-in in the stress-strain curve. Defects induced by improper coupon machining caused that cracking.