• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1667-1669
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• 2004

In this paper, the elastic epoxy added elastomer having viscoelasticity to existing epoxy was measured thermal, structural properties by DSC (Differential Scanning Calorimetry) and FESEM (Field Emission Scanning Electron Microscope). Specimens were made of dumbbell forms by the ratio of 5, 10, 15, and 20[phr] by regulation with elastomer contents. The measurement temperature dimensions of DSC were -20[$^{\circ}C$] to 150[$^{\circ}C$] and rising temperature was 4[$^{\circ}C$/min]. Also we observed structure through FESEM at the magnification of 1000 times with the voltage of 15[kV] after breaking by quenching specimens. As experimental results, we could know that thermal and structural properties were improved quantity according to decrease of elastomer contents. Namely, it increased glass transition temperature, high temperature, and matrix structure. In general, thermal, structural properties of 15[phr] was excellent among the specimens.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.95-100
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• 1997

• Proceedings of the Korean Vacuum Society Conference
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• 1998.06a
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• pp.37-37
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• 1998

• Proceedings of the Korean Vacuum Society Conference
• /
• 1998.06a
• /
• pp.123-123
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• 1998

• Proceedings of the Korean Vacuum Society Conference
• /
• 2009.08a
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• pp.342-342
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• 2009

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.11a
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• pp.139-139
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• 2001

• Proceedings of the Korean Vacuum Society Conference
• /
• 2001.07a
• /
• pp.47-47
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• 2001

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.86.4-86
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• 1998

• Computers and Concrete
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• v.7 no.5
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• pp.469-482
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• 2010

This paper investigates the concrete permeability through a numerical and statistical approach. Concrete is considered as a random heterogeneous composite of three phases: aggregates, interfacial transition zones (ITZ) and matrix. The paper begins with some classical bound and estimate theories applied to concrete permeability and the influence of ITZ on these bound and estimate values is discussed. Numerical samples for permeability analysis are established through random aggregate structure (RAS) scheme, each numerical sample containing randomly distributed aggregates coated with ITZ and dispersed in a homogeneous matrix. The volumetric fraction of aggregates is fixed and the size distribution of aggregates observes Fuller's curve. Then finite element method is used to solve the steady permeation problem on 2D numerical samples and the overall permeability is deduced from flux-pressure relation. The impact of ITZ on overall permeability is analyzed in terms of ITZ width and contrast ratio between ITZ and matrix permeabilities. Hereafter, 3680 samples are generated for 23 sample sizes and 4 contrast ratios, and statistical analysis is performed on the permeability dispersion in terms of sample size and ITZ characteristics. By sample theory, the size of representative volume element (RVE) for permeability is then quantified considering sample realization number and expected error. Concluding remarks are provided for the impact of ITZ on concrete permeability and its statistical characteristics.

• Applied Science and Convergence Technology
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• v.26 no.5
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• pp.143-147
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• 2017

Structural studies on the addition characteristics of Nb ions to $BaTiO_3$ solid solutions were performed by XRD and SEM/EDS technique. The X-ray diffraction peaks of the (111), (200) and (002) planes of Nb-doped $BaTiO_3$ solid solutions with different mole% of Nb were analyzed. We also investigated the relationship between the dielectric and structural properties of Nb-doped $BaTiO_3$. The transition temperatures of $BaTiO_3$ solid solution doped with 0.5mole%Nb and 1.0 mole%Nb were ${\sim}116^{\circ}C$ and ${\sim}87^{\circ}C$, respectively, which were found to be shifted to very low temperature from the transition temperature of pure $BaTiO_3$ (about $125^{\circ}C$). As a result of analysis of 1/K versus T and ln[$(1/K)-(1/K_m)$ versus ($T-T_m$)] of the two compositions used in this experiment, the diffusivity slightly differs from that of pure $BaTiO_3$ at temperatures above Curie temperature. And this characteristic was analyzed by applying the modified Curie-Weiss law.