• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.225-226
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• 2006

In this present investigation, Metal Injection Moulding (MIM) of M2 High Speed Steel (HSS) parts using a wax-High Density Polyethylene (HDPE) binder is shown. The elimination of organic binder was carried out by thermal debinding under inert atmosphere. In order to keep carbon in the sample that could improve the sintering process, incomplete debinding was performed between 450 and $600^{\circ}C$. The specimens were sintered at temperatures between 1210 and $1280^{\circ}C$ in high vacuum atmosphere, obtaining the 98% of the theoretical density. In the samples with higher residual carbon content, the sintering window was extended up to 20 degrees and the optimum temperature was lower.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.449-450
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• 2006

This paper described the preparation method for composing high-grade synthetic diamond by water atomizing using FeNi30 powder catalyst. The objective of this article is about powder making process using super high water atomizing in the atmosphere of inert gas, and then corroded the powder with a corrosion inhibitor. Finally, FeNi30 catalyst powder with lower oxygen content and good sphericity is produced. The experiment of making diamonds by using cubic press and the performance of the diamonds are also discussed.

• Analytical Science and Technology
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• v.16 no.4
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• pp.261-268
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• 2003

To investigate the matrix effect of sample for hydrogen analysis by inert gas fusion-thermal conductivity detection, calibration factor for the hydrogen analyser of the inert gas fusion-thermal conductivity detection method was measured with hydrogen standard materials in Ti, Zr-2.5Nb and by hydrogen gas dosing method. Also the hydrogen extraction efficiency for the different sample matrix, Ti and Zr-2.5Nb, was evaluated without adding tin flux. The calibration factor of the hydrogen analyser which was calibrated by hydrogen standard material in Zr-2.5Nb and Ti was 2~3% and 14% higher than that by hydrogen gas dosing method, respectively. Based on the results of calibration factor measurement, it could be concluded that the hydrogen extraction efficiency of the Ti matrix sample will be 12% lower than that of the Zr-2.5Nb. And according to the experimental results of hydrogen recovery test by no tin flux, the hydrogen recovery percentage of the Ti and Zr-2.5Nb matrix sample was about 70% but the recovery rate of Ti matrix sample was slightly lower than that of Zr-2.5Nb.

• Journal of Conservation Science
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• v.25 no.4
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• pp.465-471
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• 2009

In this study, the substitution fumigation gases (15% Ethylene Oxide + 85% HFC 134a, 20% Ethylene Oxide + 80% $CO_2$, 99% Sulfuryl Fluoride + 1% Inert Gas) were applied on the metal, pigment, fabric and paper specimen. The result of the fumigation treatment with 15% Ethylene Oxide + 85% HFC 134a (200g/$m^3$, 48hours) is the color changes (${\Delta}E$) of 1st and 2nd Cu specimens showed significant difference as 3.40, 4.17. On the other hand, other specimens except for Cu showed less than 3.0 in chrominance values. The result with 20% Ethylene Oxide + 80% $CO_2$ (150g/$m^3$, 48hours) is that the color changes (${\Delta}E$) of 1st and 2nd specimens were overall less than 3.0 so that color differences were subtle and hardly recognized with naked eyes. So it is proved that the fumigation treatment with Ethylene Oxide 20% + $CO_2$ 80% is relatively stable on materials in this study. In the case of 99% Sulfuryl Fluoride + 1% Inert Gas (50g/$m^3$, 48hours), the color difference of Lead red ($PbO_4$) of pigment was more than 3.0 that was compared with contrast specimens. But chrominance values in the other specimens were less than 3.0 on average.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.7-11
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• 2012

Plasma electrolytic oxidation of magnesium alloys is a well known technique to produce corrosion and wear resistant coatings. The addition of particles to the electrolyte provides a possibility to produce coatings with an increasing range of composition by in-situ incorporation of those particles into the coating. An extensive literature review has revealed that the mode of incorporation depends mainly on the melting point of the used particles and the energy provided by the discharges of the PEO process. The spectrum ranges from inert to partly reactive incorporation, but a complete reactive incorporation and a formation of a new single phase coating was not observed so far. Thus a new approach in PEO processing is introduced using specific particles as a kind of sintering additive, changing not only the composition but lowering the melting temperature and increase the liquid phase fraction during the discharges, resulting in a new amorphous coating.

• Journal of Magnetics
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• v.7 no.3
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• pp.63-71
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• 2002

Three fabrication techniques for forming thin barrier layer with uniform thickness and large barrier height in magnetic tunnel junction (MTJ) are discussed. First, the effect of immiscible element addition to Cu layer, a high conducting layer generally placed under the MTJ, is investigated in order to reduce the surface roughness of the bottom ferromagnetic layer, on which the barrier is formed. The Ag addition to the Cu layer successfully realizes the smooth surface of the ferromagnetic layer because of the suppression of the grain growth of Cu. Second, a new plasma source, characterized as low electron energy of 1 eV and high density of $10^{12}$ $cm^{-3}$, is introduced to the Al oxidation process in MTJ fabrication in order to reduce damages to the barrier layer by the ion-bombardment. The magnetotransport properties of the MTJs are investigated as a function of the annealing temperature. As a peculiar feature, the monotonous decrease of resistance area product (RA) is observed with increasing the annealing temperature. The decrease of the RA is due to the decrease of the effective barrier width. Third, the influence of the mixed inert gas species for plasma oxidization process of metallic Al layer on the tunnel magnetoresistance (TMR) was investigated. By the use of Kr-O$_2$ plasma for Al oxidation process, a 58.8 % of MR ratio was obtained at room temperature after annealing the junction at $300{^{\circ}C}$, while the achieved TMR ratio of the MTJ fabricated with usual Ar-$0_2$ plasma remained 48.4%. A faster oxidization rate of the Al layer by using Kr-O$_2$ plasma is a possible cause to prevent the over oxidization of Al layer and to realize a large magnetoresistance.

• The Korean Journal of Pesticide Science
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• v.8 no.2
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• pp.88-94
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• 2004

In order to evaluate NMR spectrometer as the analytical tool for identification of individual adjuvant in crop protection products, the standard sample of individual adjuvant was analyzed by NMR spectrometer and then the formulation of crop protection products was also analyzed. Almost polymer system of surfactant was a co-polymer and there was an excess of ethylene. The most intense signal comes from long polyethylene blocks, 70.5 ppm. The carbonyl groups of ester group resonate at 173.5 ppm. Analytical sample was prepared in NMR tube without extraction, cleanup, concentration, or chromatographic separation. Identification of individual adjuvant in crop protection products was conducted by comparison of sample and reference spectra. NMR spectrometer was useful to analyze adjuvant in crop protection products without preparation process.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.701-708
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• 2011

Although Titanium material has superior properties, it belongs to difficult-to-machine materials. The present research applies magnetic abrasive finishing to precision machining of internal-face of titanium pipes, and analyzed & assessed the influence of grinding conditions on magnetic abrasive effects through the removed amount and surface roughness of materials. There was the influence on grinding properties according to change of rotational speed, a total input of mixed powder and an input of grinding liquid, and when the total input, rotational speed and ratio of electrolytic iron versus magnetic abrasives are 8g and 1000rpm, it was most advantageous in aspects of surface roughness and material removal amount, and the grinding liquid remarkably improved the surface roughness and material removal amount only with addition of trace amounts of light oil rather than dry machining conditions. And a result of considering the influence on grinding properties by using an inert gas (Argon gas) for improving grinding properties of the internal-face of titanium pipe, the present research has obtained improvement effects in the removal amount and surface roughness through utilization of an inert gas.

• Membrane Journal
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• v.20 no.4
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• pp.267-277
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• 2010

Gas separation membranes have been developed for decades in various areas to replace the conventional processes. Membrane processes for gas separation have many advantages of energy saving, compact size, and easy scale-up. Nowadays, gas separation processes is widely spreaded in nitrogen generating system, hydrogen generating system, membrane dryer, on board inert gas generating system, natural gas purification, biogas purification and fuel cells. Carbon dioxide separation process using membrane would be a strong candidate of carbon dioxide capturing process. In order to broaden the scope of application of gas separation membranes, development of new materials which can overcome the borderline of Robeson's plot should be necessary, so that many researchers and companies are trying to develop the new materials like polymers containing cardo and spiro group and PIMs (polymers for intrinsic microporosity).

• Composites Research
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• v.35 no.4
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• pp.242-247
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• 2022

This study has a different direction from the existing technology of applying recycled carbon fiber obtained by recycling waste CFRP to CFRP again. A study was conducted to utilize recycled carbon fiber as a raw material for manufacturing a carbon/carbon (C/C) composite material comprising carbon as a matrix. First, it was attempted to recycle a commonly used epoxy resin composite material through a thermal decomposition process. By applying the newly proposed oxidation-inert atmosphere conversion technology to the pyrolysis process, the residual carbon rate of 1~2% was improved to 19%. Through this, the possibility of manufacturing C/C composite materials utilizing epoxy resin was confirmed. However, in the case of carbon obtained by the oxidation-inert atmosphere controlled pyrolysis process, the degree of oxygen bonding is high, so further improvement studies are needed. In addition, short-fiber C/C composite material specimens were prepared through the crushing and disintegrating processes after thermal decomposition of waste CFRP, and the optimum process conditions were derived through the evaluation of mechanical properties.