• Composites Research
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• v.15 no.2
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• pp.32-39
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• 2002

This study focused on the introduction of processing procedure for microcapsules loaded with the healing agent and then microcapsules with the healing agent were manufactured by experiments. The DCPD (dicyclopentadiene) was used for the healing agent and the shell of microcapsules was consisted of urea-formaldehyde resin. The magnitude and the site distribution of microcapsules were measured by a particle size analyzer using laser diffraction technique. Thermal analysis was conducted by using a DSC fur the healing agent, microcapsules without the healing agent, and microcapsules with the healing agent. Also thermal stability was investigated by using a TGA under continuous and isothermal heating conditions far the healing agent, microcapsules without the healing agent, microcapsules with the healing agent. According to the results. microcapsules with the healing agent were verified to be so thermally stable that the healing agent could not evaporate until the shell of microcapsules were burned.

• Journal of Conservation Science
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• v.30 no.4
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• pp.457-466
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• 2014

Rigorous analysis was performed to identify the structure and materials of the murals to study techniques used on mural tombs of ancient Daegaya era(6th century). The murals were painted by applying mortar on the walls and the ceiling after building a stone chamber and creating ground layers on mortar layers. Mud was applied on most of the mortar layers on four sides of the walls except the ceiling. Sand was not used in mortar but was made of materials with pure calcium substances. In addition, shells in irregular sizes with incomplete calcination were mixed; and the mortar's white powder was inferred as lime obtained by calcination of oyster shells. Kaolinite($Al_2Si_2O_5(OH)_4$) was used in the ground layer, Cinnabar(HgS) was used for red pigment, Malachite($Cu_2CO_3(OH)_2$) for green and Lead white($PbCO_3{\cdot}Pb(OH)_2$) for white. Mud plaster was applied on the mortar and was composed thinly and densely using clayey of particle size smaller than that of medium sand. It was assumed that the finishing was for repair after long time had passed since the mortar layer came off. Using lime made with oyster shells as mortar is unprecedented in ancient Korean mural tombs and its durability was very poor, suggesting that Gaya's mortar production technique was relatively behind compared to that of Koguryo's in the same era.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.375-387
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• 2004

A new finite element model will be presented to analyze the nonlinear behavior of RC beams and slabs strengthened by a patch repair. The numerical approach is based on the p-version degenerate shell element including theory of anisotropic laminated composites, theory of materially and geometrically nonlinear plates. In the nonlinear formulation of this model, the total Lagrangian formulation is adopted with large deflections and moderate rotations being accounted for in the sense of von Karman hypothesis. The material model is based on hardening rule, crushing condition, plate-end debonding strength model and so on. The Gauss-Lobatto numerical quadrature is applied to calculate the stresses at the nodal points instead of Gauss points. The validity of the proposed p-version nonlinear finite element model is demonstrated through the load-deflection curves, the ultimate loads, and the failure modes of RC beams or slabs bonded with steel plates or FRP plates compared with available result of experiment and other numerical methods.