• Polymer(Korea)
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• v.35 no.3
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• pp.265-271
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• 2011

Graphene oxide (GO) was prepared by the Hummers and Offeman method from graphite. Reduced graphene oxide (EGO) and functionalized graphenes were synthesized from GO by using hydrazine hydrate and amine-functionalized alkyl groups, respectively. The structures of the GO, EGO, and functionalized graphenes were identified by FTIR and $^{13}C$ NMR. In addition, we examined the thermal stability, morphology and dispersibility of the materials in various organic solvents. AFM disclosed that GO and RGO consisted of one- or two-layer graphene regions throughout the film. However, the functionalized graphene films showed average thicknesses of 2.26~3.30 nm, The thermal stability of the functionalized graphenes was poorer than that of the EGO. The functionalized graphenes were well dispersed in toluene or chloroform, as evidenced by the lack of the characteristic graphite reflection in the solutions.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.343-350
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• 2022

In recent years, nanomaterials, such as nano-silica, carbon nanotubes, and graphene oxide (GO), have been suggested to improve the properties of the interfacial transition zone (ITZ) between aggregates and cement pastes, which has most adversely affected the strength of quasi-brittle concrete. Among the nanomaterials, GO with superior dispersibility has been reported to be effective in improving the properties of ITZ of normal-strength concrete by forming interfacial chemical bonds with Ca²⁺ ions abundant in ITZ. In this study, the effect of GO on the properties of ITZ in the high-strength mortar was elucidated by calculating the change in hydration heat release, ITZ thickness, and the porosity around ISO sand, which was obtained with isothermal calorimetry tests and scanning electron microscope image analysis, respectively.

• Journal of the Korean Geosynthetics Society
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• v.22 no.1
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• pp.1-7
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• 2023

This study has utilized self-assembled monolayers technology to improve electrical property of graphene-oxide, which has been seperated graphine powder through a chemical exfoliation. Aluminum sulfate (Al₂(SO₄)₃) was applied on graphene-oxide as a reactant, and the fundamental research was carried out to apply on the self-sensing of cement-based construction structures. Electric resistance measurement result has shown that cement-composites with GO and Al-GO can be used as a conductor, electric resistance of GO and Al-GO contained composites improved by 10.2% and 15.9% respectively when compared to the standard cement-composite. Microstructure analyzation shown the formation of Al(OH)₃ gel when Al-GO was added, which is speculated to result the smooth flow of current by improving the density of cement-composite. This implies that graphene-oxide has a possibility to be utilized as smart building materials and construction structure itself rather than just a structure.

• Journal of Microbiology and Biotechnology
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• v.34 no.6
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• pp.1229-1238
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• 2024

This study aimed to develop and assess a chitosan biomedical antibacterial gel ZincOxide-GrapheneOxide/Chitosan/β-Glycerophosphate (ZnO-GO/CS/β-GP) loaded with nano-zinc oxide (ZnO) and graphene oxide (GO), known for its potent antibacterial properties, biocompatibility, and sustained drug release. ZnO nanoparticles (ZnO-NPs) were modified and integrated with GO sheets to create 1% and 3% ZnO-GO/CS/β-GP thermo-sensitive hydrogels based on ZnO-GO to Chitosan (CS) mass ratio. Gelation time, pH, structural changes, and microscopic morphology were evaluated. The hydrogel's antibacterial efficacy against Porphyromonas gingivalis, biofilm biomass, and metabolic activity was examined alongside its impact (MC3T3-e1). The findings of this study revealed that both hydrogel formulations exhibited temperature sensitivity, maintaining a neutral pH. The ZnO-GO/CS/β-GP formulation effectively inhibited P. gingivalis bacterial activity and biofilm formation, with a 3% ZnO-GO/CS/β-GP antibacterial rate approaching 100%. MC3T3-e1 cells displayed good biocompatibility when cultured in the hydrogel extract.The ZnO-GO/CS/β-GP thermo-sensitive hydrogel demonstrates favorable physical and chemical properties, effectively preventing P. gingivalis biofilm formation. It exhibits promising biocompatibility, suggesting its potential as an adjuvant therapy for managing and preventing peri-implantitis, subject to further clinical investigations.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.2
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• pp.152-158
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• 2003

A machine-vision guided inspection system with go-no gauges for inspecting eggcrate assemblies in steam generators is considered. To locate the gauge at the right place, periodic corrective actions for its position and traveling direction are required. We present a machine vision algorithm for determining inserting position and traveling direction of the go-no gauge. The overall procedure of the algorithm is composed of camera calibration, eggcrate image preprocessing, grid-height adjustment, intersection point estimation between two intersecting grids, and adjustment of position and traveling direction of the gauge. The intersection point estimation is performed by using linear regression with a constraint. A test with a real eggcrate specimen shows the feasibility of the algorithm.

• Annual Conference of KIPS
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• 2017.04a
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• pp.64-67
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• 2017

Applying concurrent structure and parallel processing are a common issue for these day's programs. In this research, Dynamic Programming is used to compare the parallel performance of Go language and Intel C++ Thread Building Blocks. The experiment was performed on 4 core machine and its result contains execution time under Simultaneous Multi-Threading environment. Static Optimal Binary Search Tree was used as an example. From the result, the speed-up of Go was higher than the number of cores, and that of TBB was close to it. TBB performed better in general, but for larger scale, Go was partially faster than the other.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.1
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• pp.60-66
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• 2002

In this paper, a new target pointing guidance algorithm is proposed by combining the optimal target pointing solution and a simple time-to-Go estimator. Also investigated are some properties of the guidance algorithm which include a relation to conventional PNG, convergence region and convergence trajectories of error states according to the time-to-go estimator gain. Some guidelines for designing the pointing guidance law are commented based on the convergence properties. A design example in the case of large initial heading errors is presented and its performance is investigated by simulation.

• Transactions on Electrical and Electronic Materials
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• v.16 no.1
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• pp.49-52
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• 2015

The change of the chemical structure of graphene oxide (GO) was investigated by periodical sampling of GO during exfoliation by using a sonicator. A significant amount of GO was exfoliated during up to 10 hr of sonication. Raman and Fourier transform infrared spectroscopy revealed a continuous increase of the G/D or C=C/C=O peak ratio of GO, as the sonication time increases. The photoluminescence (PL) intensity of each GO sample also decreased as a function of the sonication time. PL excitation spectra with three major peaks indicate that the sizes of $sp^2$ carbon clusters were enlarged by longer sonication. In addition, new excitation at around 300 nm proves the existence of newly developed small clusters of $sp^2$ carbons as the sonication time increased.

• Molecular & Cellular Toxicology
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• v.1 no.4
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• pp.281-283
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• 2005

Extraction of biologically meaningful data and their validation are very important for toxicogenomics study because it deals with huge amount of heterogeneous data. BINGO is an annotation mining tool for biological interpretation of gene groups. Several statistical modeling approaches using Gene Ontology (GO) have been employed in many programs for that purpose. The statistical methodologies are useful in investigating the most significant GO attributes in a gene group, but the coherence of the resultant GO attributes over the entire group is rarely assessed. BINGO complements the statistical methods with graph-theoretic measures using the GO directed acyclic graph (DAG) structure. In addition, BINGO visualizes the consistency of a gene group more intuitively with a group-based GO subgraph. The input group can be any interesting list of genes or gene products regardless of its generation process if the group is built under a functional congruency hypothesis such as gene clusters from DNA microarray analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.478-478
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• 2011

The thermomechanical and surface chemical properties of nanocomposite of poly( D, L-actic-co-glycolic acid) (PLGA) were improved significant due to concentration of graphene oxide (GO) nanosheets as nanoscale fillers to PLGA film. Thermomechanical properties of the PLGA/GO (2wt.-%.) nanocomposite were decreased crystallization and melting temperature, weight loss. The storage and loss moduli of the nanocomposite were enhanced by chemical bonding between the oxygenated functional groups of the GO nanosheets and the polymer chains in the PLGA matrix. Enhanced hydrophilicity of nanocomposite caused by embedded GO nanosheets also improved for good biocompatibility. Our findings indicate that thermomechanical properties and biocompatibility of nanocomposite embedded with GO nanosheets are attractive candidates for use in biomedical applications such as scaffolds.