• Korean Journal of Metals and Materials
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• v.46 no.3
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• pp.111-117
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• 2008

The effects of the dissolved cementite on the mechanical properties have been experimentally investigated. The steel wires were fabricated depending on the carbon content of 0.82 and 1.02 wt.% and drawing strain from 4.12 to 4.32. The bending fatigue resistance and torsion ductility were measured by a hunter fatigue tester and torsion tester specially designed for thin-sized wires. The results showed that as the drawing strain and carbon content increased, the fatigue resistance and the torsional ductility of the steel wires decreased, while the tensile strength increased. In order to elucidate this behavior, the microstructure in terms of lamellar spacing (${\lambda}_p$), cementite thickness ($t_c$) and morphology of cementite was observed by advanced analysis techniques such as transmission electron microscope (TEM) and 3 dimensional atom probes (3-D AP).

• Structural Engineering and Mechanics
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• v.87 no.4
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• pp.375-389
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• 2023

In many fiber concrete beams with Carbon Fiber Reinforced Polymer (CFRP), debonding occurs between the carbon sheets and the concrete due to the low strength of the bonding resin. A total of 42 fiber concrete beams with a cross-section of 10×10 cm with a span length of 50 cm are fabricated and retrofitted with CFRP and subjected to a 4-point bending test. Graphene Oxide (GO) at 1, 2, and 3 wt% of the resin is used to improve the mechanical properties of the bonding resins, and the effect of length, width, and the number of layers of CFRP and resin material are investigated. The crack pattern, failure mode, and stress-strain curve are analyzed and compared in each case. The results showed that adding GO to polyamine resin could improve the bonding between the resin and the fiber concrete beam. Furthermore, the optimum amount of nanomaterials is equal to 2% by the weight of the resin. Using 2% nanomaterials showed that by increasing the length, width, and number of layers, the bearing and stiffness of fiber concrete beams increased significantly.

• Carbon letters
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• v.11 no.4
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• pp.347-356
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• 2010

Recently, the use of thermal conductive polymeric composites is growing up, where the polymers filled with the thermally conductive fillers effectively dissipate heat generated from electronic components. Therefore, the management of heat is directly related to the lifetime of electronic devices. For the purpose of the improvement of thermal conductivity of composites, fillers with excellent thermally conductive behavior are commonly used. Thermally conductive particles filled polymer composites have advantages due to their easy processibility, low cost, and durability to the corrosion. Especially, carbon-based 1-dimensional nanomaterials such as carbon nanotube (CNT) and carbon nanofiber (CNF) have gained much attention for their excellent thermal conductivity, corrosion resistance and low thermal expansion coefficient than the metals. This paper aims to review the research trends in the improvement of thermal conductivity of the carbon-based materials filled polymer composites.

• Carbon letters
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• v.15 no.4
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• pp.219-237
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• 2014

The element carbon has been used as a source of energy for the past few hundred years, and now in this era of technology, carbon has played a significant and very prominent role in almost all fields of science and technology. So as an honour to this marvellous element, we humans should know about its various forms of existence. In this review article, we shed light on all possible carbon-allotropes; similarities in their synthesis techniques and the starting materials; their wide range of possible availability; and finally, future perspectives and applications. A brief introduction is given on the types, structures, and shapes of the allotropes of carbon for a better understanding.

• Carbon letters
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• v.10 no.1
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• pp.5-8
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• 2009

We measured the non-carbon content of single-walled carbon nanotubes (SWCNTs) in SWCNT soot using thermogravimetric analysis. The weight increased percentage by the oxidation of metal in the raw soot is well obtained by TGA graph which was confirmed with ICP-AES, XRD, and XPS. This work will be very useful for the purity precise evaluation of SWCNT with UN-vis-NIR spectroscopy.

• Composites Research
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• v.36 no.6
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• pp.408-415
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• 2023

The formation of bonding configurations such as pyridinic-N, pyrrolic-N, and graphitic-N by nitrogen doping plays a crucial role in imparting distinct physical properties to carbon nanomaterials. In this study, we propose a simple and cost-effective approach to regulate nitrogen dopant configurations in carbon nanotubes (CNTs) by mixing melamine as a dopant source. We employed three distinct mechanical mixing techniques, namely magnetic stirring, bath sonication and tip sonication. The higher the ratio of melamine to CNT, the higher the ratio of Pyrrolic-N, and when mixed through stirring, the highest ratio of Pyridinic-N was shown. The facile method proposed in this study, which can easily form various types of nitrogen dopants in carbon nanotubes, is expected to facilitate the application of nitrogen-doped carbon nanomaterials.

• Elastomers and Composites
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• v.52 no.1
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• pp.69-80
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• 2017

Conducting polymers and carbon nanomaterials offer a wide range of applications because of their unique soft conducting properties. Specifically, these conducting polymer-carbon nanocomposites have recently been utilized in bioengineering applications, partly because of their improved biocompatibility compared to conventional conducting materials such as metals and ceramics. Based on the assumption that these composites offer an important application potential as functional materials for biomedical devices or even as biomaterials, this review surveys the recent research trends on conducting polymers-carbon nanocomposites, focusing on bioengineering applications such as polyaniline (PANI), poly(3,4-ethylenedioxythiophene) or PEDOT, polypyrrole (Ppy), and carbon nanotubes and graphene.

• Carbon letters
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• v.11 no.1
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• pp.9-12
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• 2010

The synthesis of $C_{60}$@MWCNT was carried out at room temperature (${\sim}25^{\circ}C$) from arc-discharge prepared Multi-wall carbon nanotubes (MWCNTs). They were oxidized and acid treated for tube opening. Then $C_{60}$ molecules were encapsulated into MWCNTs by wetting them with $C_{60}$-toluene solution for several minutes followed by ultrasonification. $C_{60}$@MWCNT was cleaned by pure toluene to remove any excess $C_{60}$. $C_{60}$@MWCNT was characterized by electron microscopy, which showed large scale filling of $C_{60}$ into MWCNTs. It was observed that the mechanism of insertion of $C_{60}$ into MWCNTs may be due to the capillary suction at the opening ends of MWCNTs.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.488.2-488.2
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• 2014

Carbon-based materials such as carbon nanotubes and graphene have emerged as promising building blocks in applications for nanoelectronics and energy devices due to electrical property, ease of processability, and relatively inert electrochemistry. In recent years, there has been considerable interest in core-shell nanomaterials, in which inorganic nanowires are surrounded by inorganic or organic layers. Especially, carbon encapsulated semiconductor nanowires have been actively investigated by researchers in lithium ion batteries. We report a method to synthesize silicon nanowire (SiNW) core/carbon shell structures by chemical vapor deposition (CVD), using methane (CH4) as a precursor at growth temperature of $1000{\sim}1100^{\circ}C$. Unlike carbon-based materials synthesized via conventional routes, this method is of advantage of metal-catalyst free growth. We characterized these materials with FE-SEM, FE-TEM, and Raman spectroscopy. This would allow us to use these materials for applications ranging from optoelectronics to energy devices such as solar cells and lithium ion batteries.

• Carbon letters
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• v.20
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• pp.32-38
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• 2016

In this study, cellulose nanoplates (CNPs) were fabricated using cellulose nanocrystals obtained from commercial microcrystalline cellulose (MCC). Their pyrolysis behavior and the characteristics of the product carbonaceous materials were investigated. CNPs showed a relatively high char yield when compared with MCC due to sulfate functional groups introduced during the manufacturing process. In addition, pyrolyzed CNPs (CCNPs) showed more effective chemical activation behavior compared with MCC-induced carbonaceous materials. The activated CCNPs exhibited a microporous carbon structure with a high surface area of 1310.6 m²/g and numerous oxygen heteroatoms. The results of this study show the effects of morphology and the surface properties of cellulose-based nanomaterials on pyrolysis and the activation process.