• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.56-56
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• 2018

Transparent conductive oxides (TCOs) have attracted attention due to their high electrical conductivity and optical transparency in the visible region. Consequently, TCOs have been widely used as electrode materials in various electronic devices such as flat panel displays and solar cells. Previous studies on TCOs focused on their electrical and optical performances; there have been numerous attempts to improve these properties, such as chemical doping and crystallinity enhancement. Recently, due to rapidly increasing demand for flexible electronics, the academic interest in the mechanical stability of materials has come to the fore as a major issue. In particular, long-term stability under bending is a crucial requirement for flexible electrodes; however, research on this feature is still in the nascent stage. Hydrogen-incorporated amorphous In-Sn-O (a-ITO) thin films were fabricated by introducing hydrogen gas during deposition. The hydrogen concentration in the film was determined by secondary ion mass spectrometry and was found to vary from $4.7{\times}10^{20}$ to $8.1{\times}10^{20}cm^{-3}$ with increasing $H_2$ flow rate. The mechanical stability of the a-ITO thin films dramatically improved because of hydrogen incorporation, without any observable degradation in their electrical or optical properties. With increasing hydrogen concentration, the compressive residual stress gradually decreased and the subgap absorption at around 3.1 eV was suppressed. Considering that the residual stress and subgap absorption mainly originated from defects, hydrogen may be a promising candidate for defect passivation in flexible electronics.

• Advances in concrete construction
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• v.10 no.6
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• pp.559-571
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• 2020

This study aimed to inspect the axial compression mechanical performance of basalt-fiber-reinforced recycled - concrete (BFRRC)-filled square steel tubular stub column. The replacement ratio of recycled coarse aggregate (RCA) and the basalt fiber (BF) dosage were used as variation parameters, and the axial compression performance tests of 15 BFRRC-filled square steel tubular stub column specimens were conducted. The failure mode and the load-displacement/strain curve of the specimen were measured. The working process of the BFRRC-filled square steel tubular stub column was divided into three stages, namely, elastic-elastoplasticity, sudden drawdown, and plasticity. The influence of the design parameters on the peak bearing capacity, energy dissipation performance, and other axial compression performance indexes was discussed. A mathematical model of segmental stiffness degradation was proposed on the basis of the degradation law of combined secant-stiffness under axial compression. The full-process curve equation of axial compressive stress-strain was proposed by introducing the influencing factors, including the RCA replacement ratio and the BF dosage, and the calculated curve agreed well with the test-measured curve.

• Earthquakes and Structures
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• v.25 no.1
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• pp.57-67
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• 2023

The buckling of longitudinal reinforcements under seismic loading accelerates the degradation of the bearing capacity of reinforced concrete columns. The traditional hysteretic constitutive model of reinforcement, which does not consider buckling, usually overestimates the seismic performance of pier columns. Subsequent researchers have also proposed many models including the buckling effects. However, the accuracy of these hysteretic constitutive models proposed for simulating the buckling behavior is inadequate. In this study, based on their works, the influence of historical events on buckling is considered, the path of the re-tensioning phase is corrected by adjusting the boundary lines, and the positions of the onset buckling point and compressive buckling path during each buckling deformation are corrected by introducing correction parameters and a boundary line. A modified hysteretic constitutive model is obtained, that can more accurately reflect the buckling behavior of reinforcements. Finally, a series of hysteresis tests of reinforcements with different slenderness ratios were then conducted. The experimental results verify the effectiveness of the proposed modified model. Indicating that the modified model can more accurately simulate the equivalent stress-strain relationship of the buckling reinforcement segment.