• Journal of the Korean institute of surface engineering
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• v.52 no.3
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• pp.150-155
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• 2019

The carbon electrode was modified through manganese-catalyzed hydrogenation method for high energy density vanadium redox flow battery (VRFB). During the catalytic hydrogenation, the manganese oxide deposited at the surface of the carbon electrode stimulated the conversion reaction from carbon to methane gas. This reaction causes the penetration of the manganese and excavates a number of cavities at electrode surface, which increases the electrochemical activity by inducing additional electrochemically active site. The formation of the porous surface was confirmed by the scanning electron microscopy (SEM) images. Finally, the electrochemical performance test of the electrode with the porous surface showed lower polarization and high reversibility in the cathodic reaction compared to the conventional electrode.

• Progress in Medical Physics
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• v.31 no.3
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• pp.71-80
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• 2020

This paper provides a brief review of the advanced technologies for carbon ion radiotherapy (CIRT), with a focus on current developments. Compared to photon beam therapy, treatment using heavy ions, especially a carbon beam, has potential advantages due to its physical and biological properties. Carbon ion beams with high linear energy transfer demonstrate high relative biological effectiveness in cell killing, particularly at the Bragg peak. With these unique properties, CIRT allows for accurate targeting and dose escalation for tumors with better sparing of adjacent normal tissues. Recently, the available CIRT technologies included fast pencil beam scanning, superconducting rotating gantry, respiratory motion management, and accurate beam modeling for the treatment planning system. These techniques provide precise treatment, operational efficiency, and patient comfort. Currently, there are 12 CIRT facilities worldwide; with technological improvements, they continue to grow in number. Ongoing technological developments include the use of multiple ion beams, effective beam delivery, accurate biological modeling, and downsizing the facility.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.7
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• pp.928-938
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• 1997

The end winding is an important part in induction motor for thermal analysis. But there is little information on the heat transfer coefficient of that surfaces because of geometrical complexity. So our experimental object is to know the heat transfer coefficient of end winding and find the optimum design parameter of rotor fan. Carbon coated papers were used for a uniform heat generating surfaces which were easy to fabricate. The experiments of some parameters were performed as varying rotation speed of rotor fan. We obtained the local and average Nusselt number of the end winding surfaces by correcting radiation and conduction losses errors. The results showed that the average Nusselt number increased with rotor fan blade number and width but decreased with end winding length. However, the increasing limits existed in the case of rotor fan width and blade number. So optimum design value were obtained for rotor fan width and blade numbers.

• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.491-496
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• 2010

This study aimed to obtain equilibrium concentration on adsorption removal of phosphorus by activated carbon, to express the adsorption characteristics following Freundlich isotherm and also, based on the value obtained, to investigate the relationship between physical properties of activated carbon and dynamics of phosphorus removal by obtaining rate constant and effective pore diffusivity. The results summarized from this study are as follows. Phosphorus adsorption equilibrium reaching time of powdered activated carbon was reduced as the dosage of activated carbon increases, while granular activated carbon despite increased dosage did not have influence on adsorption equilibrium reaching times of phosphorus as well, taking more than 10 hours. It was also noted that powdered activated carbon showed better adsorption ability than granular activated carbon. The value of constant (f) of Freundlich isotherm of powered activated carbon on phosphorus was 4.26 which is bigger than those of granular activated carbon. The adsorption rate constant on phosphorus of powered activated carbon with low effective diameter and iodine number was highest as $8.888hr^{-1}$ and the effective pore diffusivity ($D_e$) was lowest as $2.45{\times}10^{-5}cm^2/hr$, and the value of phosphorus adsorption rate constant of granular activated carbon was $0.174{\sim}0.372hr^{-1}$, It was revealed that, with the same amount of dosage, the adsorptive power of activated carbon with lower effective diameter was better and its rate constant was also high.

• Journal of Electrochemical Science and Technology
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• v.8 no.4
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• pp.338-343
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• 2017

Activated carbon has lower electrical conductivity and reliability than other carbonaceous materials because of the oxygen functional groups that form during the activation process. This problem can be overcome by doping the material with heteroatoms to reduce the number of oxygen functional groups. In the present study, N, F co-doped activated carbon (AC-NF) was successfully prepared by a microwave-assisted hydrothermal method, utilizing commercial activated carbon (AC-R) as the precursor and ammonium tetrafluoroborate as the single source for the co-doping of N and F. AC-NF showed improved electrical conductivity ($3.8\;S\;cm^{-1}$) with N and F contents of 0.6 and 0.1 at%, respectively. The introduction of N and F improved the performance of the pertinent supercapacitor: AC-NF exhibited an improved rate capability at current densities of $0.5-50mA\;cm^{-2}$. The rate capability was higher compared to that of raw activated carbon because N and F codoping increased the electrical conductivity of AC-NF. The developed method for the co-doping of N and F using a single source is cost-effective and yields AC-NF with excellent electrochemical properties; thus, it has promising applications in the commercialization of energy storage devices.

• Journal of the Korean Chemical Society
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• v.6 no.1
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• pp.88-93
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• 1962

The telomerization of vinyl acetate with carbon tetrachloride, chloroform and monochlorobenzene were investigated with respect to the synthesis of those telomers, properties and molecular weights of the formed telomers, and reaction mechanisms. Vinyl acetate reacted with carbon tetrachloride and chloroform to form telomers at 70-90$^{\circ}C$ and 60-70$^{\circ}C$, respectively and it formed polymer with monochlorobenzene. As a chain transfer agent, carbon tetrachloride was more effective than chloroform. In the telomerization of vinyl acetate and carbon tetrachloride: 1) The average molecular weight of the telomer decreased as the mole ratio of carbon tetrachloride to vinyl acetate increased. The optimum conditions for the highest yield of the telomer were as follows: Mole ratio of carbon tetrachloride to vinyl acetate : 2.5 Reaction time : 20 hours. 2) As the reaction proceeded, the refractive index and average molecular weight of the telomer increased rapidly in the first 10 hours but the increase was slow through the next 10 hours, so that, the average recurring number(n) of taxogen in the final product reached an almost definite value, i.e., 3. The telomer formed in the telomerization of vinyl acetate with carbon tetrachloride and chloroform turned to brown color in the air due to decomposition or polymerization. The suggested telomerization mechanism was supported by the hexachloroethane detected in the course of reaction.

• Carbon letters
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• v.27
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• pp.98-107
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• 2018

Free-standing electrodes of CuO nanorods in carbon nanotubes (CNTs) are developed by synthesizing porous CuO nanorods throughout CNT webs. The electrochemical performance of the free-standing electrodes is evaluated for their use in flexible lithium ion batteries (LIBs). The electrodes comprising CuO@CNT nanocomposites (NCs) were characterized by charge-discharge testing, cyclic voltammetry, and impedance measurement. These structures are capable of accommodating a high number of lithium ions as well as increasing stability; thus, an increase of capacity in long-term cycling and a good rate capability is achieved. We demonstrate a simple process of fabricating free-standing electrodes of CuO@CNT NCs that can be utilized in flexible LIBs with high performance in terms of capacity and cycling stability.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.549-555
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• 1996

Diamond Like Carbon film is amorphous film which is considered to consist of three coordinate graphite structure and tetrahedron coordinate diamond structure. Its hardness, thermal conductivity and chemical stability are nearly to one of diamond. It is well known to become semi-conductor by doping of inpurity. In this study Diamond Like Carbon film was synthesized by Microwave Plasma CVD in the gas mixture of hydrogen-methan-nitrogen and doped of nitrogen on the single-crystal silicon or silica glass. The temperature of substrate and nitrogen concentration in the gas mixture had an effect on the bonding state, structural properties and conduction mechanism. The surface morphology was observed by Scanning Electron Microscope. The strucure was analyzed by laser Raman spectrometry. The bonding state was evaluated by electron spectroscopy. Diamond Like Carbon film synthesized was amorphous carbon containing the $sp^2$ and $sp^3$ carbon cluster. The number of $sp^2$ bonding increased as nitrogen concentration increased from 0 to 40 vol% in the feed gas at 1233K substrate temperature and at $7.4\times10^3$ Pa. Increase of nitrogen concentration made Diamond Like Carbon to be amorphous and the doze of nitragen could be controlled by nitrogen concentration of feed gas.

• Applied Biological Chemistry
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• v.9
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• pp.29-33
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• 1968

Through an experiment with gas chromatography carried out using diethylene glycol succinate(DEGS) as the packing material of the column, we have obtained the correction factor between the weight ratio and the peak dimension of the saturated fatty acid methyl esters of C10, C12, C14, C16, and C18 and unsaturated fatty acid methyl esters of oleic acid, linoloic acid, and linolenic acid, employing the detector of thermal conductivity type. Quantitative analysis of the fatty acids contained in rice Bran oil was performed with the above correction factor and the results are as follows; 1. Main components were found to be palmitic acid, oleic acid sand linolenic acid. No trases of capric acid (C10) lauric acid (C10) were found. 2. It was confirmed that there were straight line relation between the logarism retention time of each fatty acid and the number of carbon of saturated fatty acid or the number of double bond of other fatty acids having the same number of carbon. 3. The correction factor became larger as to the number of carbon increased up to C18 in case of saturated fatty acids, end as for other fatty acids, and as for other fatty acids of the same carbon number, it became larger according as the number of double bond increased.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1279-1280
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• 2010