• Carbon letters
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• v.2 no.1
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• pp.72-75
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• 2001

The performance of Li-ion system based on $LiCoO_2$ and Graphite is well optimized for the 3C applications. The charge-discharge mode, the manufacturing process, the cell performance and the thermal reactions affecting safety has been explained in the engineering point of view. The energy density of the current LIB system is in the range of 300~400 Wh/l. In order to achieve the energy density higher than 500 Wh/l, the active materials should be modified or changed. Adopting new high capacity anode materials would be effective to improve energy density.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.608-612
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• 2023

Nano-diamond (ND) was added during the carbon block preparation process to increase the thermal conductivity of the carbon block. Added ND controlled the generated pore of carbon block due to the volatilization of the binder pitch during the carbonization process. The ND was added to the kneading process of coke and binder pitch, and carbon blocks were prepared by pressing and carbonization. As the amount of added ND increased, the ND ratio of the carbon block increased. The added ND made a pass-way for generated gas by volatilizing the binder pitch during the carbonization process, increasing the density of the carbon block and reducing the porosity. The thermal conductivity of the carbon block was improved by increased density, lowered porosity, and the high thermal conductivity of added ND.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.4
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• pp.231-240
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• 2017

This paper aims to study a method to estimate precise carbon absorption by quantification of forest information that uses accurate LiDAR data, hyperspectral image. To estimate precise carbon absorption value by using spatial data, a problem was found out of carbon absorption value estimation method with statistical method, which is already existed method, and then offered optimized carbon absorption estimation method with spatial information by analyzing with methods of compare digital aerial photogrammetry and LiDAR data. It turned out possible Precise classification and quantification in case of using LiDAR and hyperspectral image. Various classification of tree species was possible with use of LiDAR and hyperspectral image. Classification of hyperspectral image was matched in general with field survey and Mahalanobis distance classification method. Precise forest resources could be extracted using high density LiDAR data. Compared with existing method, 19.7% in forest area, 19.2% in total carbon absorption, 0.9% in absorption per unit area of difference created, and improvement was found out to be estimated precisely in international code.

• Journal of the Korean Ceramic Society
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• v.35 no.9
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• pp.974-980
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• 1998

This study is concerned with the production of carbon fiber reinforced carbon(C/C) with polyaromatic mesophase pitch as matrix precursor and with the investigation of friction-wear characteristics in ambient air using a constant speed type of friction tester. The main problem in using the polyaromatic mesophase as the matrix precursor is the high viscosity which may limit the complete impregnation of the fiber preform in the vacuum. To solve these problems two dimensional carbon fiber fabrics were infiltrated with meso-phase pitch in the pitch impregnator. After the impregnation and the heat treatment process. C/C com-posites were characterized by density porosity to monitor the influence of high pressure and temperature. It showed that the bulk density was increased and the apparent porosity and the density increasing rate was reduced as repeating the impregnation the carbonization and the heat treatment. The friction-wear charac-teristics of C/C composites were investigated by measuring the average friction coefficient and the specific wear rate as functions friction speed and friction pressure using a constant speed type of friction tester. C/C composite4s showed the average friction coefficient to be reduced as increasing the friction speed and the friction pressure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.276-279
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• 2002

$Bi_{2}Sr_{2}CaCu_{2}O_{x}$ was prepared by the conventional method of solid state reaction and SHS method. The samples were annealed in different atmosphere in order to examine the influence of atmospheres on the carbon contents in the $Bi_{2}Sr_{2}CaCu_{2}O_{x}$ compound. The lowest carbon content in $Bi_{2}Sr_{2}CaCu_{2}O_{x}$ could be attended when the sample was annealed in $O_{2}$ at $800^{\circ}C$ for 100 hours. The $CO_{2}$ in air pollute the samples and increase the carbon content in the sintering process. The critical current density of the $Bi_{2}Sr_{2}CaCu_{2}O_{x}$ samples will decrease with the increasing carbon contents in the samples. The impurity carbon will deposit in the grain boundary, which makes critical current density lower.

• Journal of Powder Materials
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• v.3 no.1
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• pp.49-56
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• 1996

The effect of$H_{2}/N_{2}$gas sintering atmosphere on the carbon content and mechanical properties during the metal injection molding process of carbonyl iron-nickel powder was studied. The carbon content of the specimen after debinding in the pure$N_{2}$atmosphere appeared 0.78 wt%. After showing the maximum value of 1.48 wt.% in the debinding atmosphere of 10%$H_{2}/N_{2}$gas mixture, the carbon content of the debinded specimen decreased gradually with increasing the$H_2$content in the$H_{2}/N_{2}$gas mixture. The carbon contents of the sintered specimen were 0.46~0.63wt% in Na gas atmosphere, while they appeared extremely low above 40%$H_{2}/N_{2}$gas atmosphere. The relative sintered density increased abruptly from 88~90% to 93~96% with the addition of Ni, while the density nearly unchanged above 2% Ni addition. The sintered density increased with increasing the fraction of$H_{2} in H_{2}/N_{2}$gas mixture. Tensile strength and hardness increased, and elongation decreased with increasing carbon and Ni content. In spite of high carbon content of 0.63 wt%, the superior elongation value of 10% was shown.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.366-366
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• 2008

Amorphous carbon (a-C) is an interesting materials and its characteristics can be varied by tuning it $sp^3$ fractions. The $sp^3$ fraction in a-C films depends on the kinetic energy of the deposited carbon ions. In this work, a-C films was synthesized on Si(100) and glass substrates at room temperature by closed-field unbalanced magnetron (CFUBM) sputtering with the increase of graphite target power density. The structural and physical properties of films were investigated by using Raman spectroscopy, X-ray photoelectron spectrometer (XPS), nano- indentation, atomic force microscope (AFM) and contact-angle measurement. We obtained the good tribological properties, such as high hardness up to 26 GPa., friction coefficient lower than 0.1 and the smooth surface (rms roughness: 0.12 nm). The increase of the physical properties with the increase of target power density are related to the increase of nano-clusters in the carbon network. Also, these results might be due to the increase of the subplantation and resputtering by the increase of ions density in the plasma.

• Carbon letters
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• v.16 no.3
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• pp.198-202
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• 2015

Carbon-supported Pt catalyst systems containing defect adsorption sites on the anode of direct methanol fuel cells were investigated, to elucidate the mechanisms of H₂ dissociation and carbon monoxide (CO) poisoning. Density functional theory calculations were carried out to determine the effect of defect sites located neighboring to or distant from the Pt catalyst on H₂ and CO adsorption properties, based on electronic properties such as adsorption energy and electronic band gap. Interestingly, the presence of neighboring defect sites led to a reduction of H₂ dissociation and CO poisoning due to atomic Pt filling the defect sites. At distant sites, H₂ dissociation was active on Pt, but CO filled the defect sites to form carbon π-π bonds, thus enhancing the oxidation of the carbon surface. It should be noted that defect sites can cause CO poisoning, thereby deactivating the anode gradually.

• Journal of the Korean Ceramic Society
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• v.37 no.6
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• pp.569-575
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• 2000

Fabrication of carbon fiber reinforced composites was carried out by hand lay-up method. Carbon nanofibers and SiC nanofibers were used as filler in the composites fabrication. Carbon nanofibers, one of the new carbon materials, have 5∼500 nm in diameter and 5-10 nm in length. SiC nanofibers were modified by silicon monoxide vapor with carbon nanofibers. The composites were carbonized at 1000$^{\circ}C$ in a nitrogen atmosphere, and then densified by molten pitches impregnated in vacuum. Multiple cycles of liquid pitch impregnation and carbonization were carried out to obtain a desired density. The composites were characterized by density, microstructure. The inter-laminar shear strength (ILSS) test was performed for mechanical properties. For the new application, the microwave reflective proeprty of composites was investigated. Dielectric constant and permeability spectrum were measured in 12∼18 GHz frequency ranges. On the basis of the wave propagation theory in a lossy media, the reflection loss from the composite inter-layer was predict as a function of frequency.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.281-288
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• 2010

This study examined the carbon corrosion at Pt/C interface in proton exchange membrane fuel cell environment. The Pt nano particles were electrodeposited on carbon substrate, and then the corrosion behavior of the carbon electrode was examined. The carbon electrodes with Pt nano electrodeposits exhibited the higher oxidation rate and lower oxidation overpotential compared with that of the electrode without Pt. This phenomenon was more active at $75^{\circ}C$ than $25^{\circ}C$. In addition, the current transients and the corresponding power spectral density (PSD) of the carbon electrodes with Pt nano electrodeposits were much higher than those of the electrode without Pt. The carbon corrosion at Pt/C interface was highly accelerated by Pt nano electrodeposits. Furthermore, the polarization and power density curves of PEMFC showed degradation in the performance due to a deterioration of cathode catalyst material and Pt dissolution.