• Transactions of the Korean hydrogen and new energy society
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• v.17 no.4
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• pp.454-460
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• 2006

In the production of hydrogen from various sources like cracking of LPG, LNG, Crude oil, or alkaline water electrolysis, the things that we keep in mind is the entrapment of unexpected impurities in the stream of produced $H_2$. If it is true that we are not able to produce 100% pure $H_2$, then subsequent procedure is the elimination of the impurities and the determination of the concentrations of each constituents in $H_2$ stream. By the way, each country has different constituents in its fuels and unavoidablely it was cost/economy debates between coutries. Thus, in this paper, our goal is to provide current international issues for hydrogen production.

• Toxicological Research
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• v.3 no.1
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• pp.27-32
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• 1987

Ethyl acetate extracts of 6 commercial amaranths produced in 1985 and 1986 were analyzed with a gas chromatograph. The ${\alpha}$-naphthylamine ranging from 142 ppb to 4216 ppb was detected, but the ${\beta}$ naphthylamine was not detected. The mutagenicity of the ethyl acetate extract was tested using Salmonella typhimurium TA100 in the presence of the S-9 fraction. Significant mutagenic activity was seen in samples containing high levels of ${\alpha}$-naphthylamine. It is suggested that the potential hazard of amaranth to the general public should be reconsidered from the point that the impurities contained in amaranth preparations are the main sources of mutagenicity or carcinogenicity.

• 보존과학연구
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• s.26
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• pp.27-40
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• 2005

This study is to be investigated through component analysis and metallurgical texture in order to save an information of the manufacturing technique for the bronze bell in Naksan-sa. The bronze bell was analyzed with nine samples not stirred by the fire and except the contents of tin is the maximum and minimum the average of Cu is 81.8wt%, Sn is15.8wt% and indicates that some impurities are in it. With the result of an analysis of component and microtexture for impurities material which exists in it with using the SEM-EDS, the material was revealed the sulfur. As the result of these factors, the bronze bell of Naksan-sa is used from ore which mainly consist of the Chalcopyrite($CuFeS_2$) or Bornite($Cu_5FeS_4$) containing much sulfur.

• Transactions on Electrical and Electronic Materials
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• v.12 no.5
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• pp.204-208
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• 2011

In this paper, the design area of a fabricated solar cell has been analyzed with respect to its charge density. The mathematical calculation used for charge-density derivation was obtained from the 2001 version of a MATHCAD program. The parameter range for the calculations was ${\pm}1{\times}10^{17}cm^{-3}$, which is in the normal parameter range for n-type doping impurities ($7.0{\times}10^{17}cm^{-3}$) and also for p-type impurities ($4.0{\times}10^{17}cm^{-3}$). Therefore, it can be said that the fabricated solar-cell design area has a direct effect on charge-density changes.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.931-933
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• 1992

The static charges generated at the interface between the insulating oil and the solid materials, can be affected by impurities such as moisture. This paper investigated the charging tendency of clean oil and the oil with moisture in stainless steel pipe. The experimental results show that static electrification of the oil with moisture is smaller than that of the clean oil, and the oil is positively charged.

• Tribology and Lubricants
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• v.23 no.4
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• pp.143-148
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• 2007

The surface defects of an aluminum tube for an OPC drum have been analyzed using a scanning microscopy(SEM) and an energy dispersive X-ray analyze.(EDX). The SEM/EDX system, which may provide good information on the surface defects and their distributions, provides an optical diameter of an impurity and a chemical composition. These are strongly related on the coated film thickness and quality of an OPC drum, which is a key element of a toner cartridge for a laser printer. The experimental results show that the local deformations, scratch wear, and flaws are produce the non-uniform coating layers, which may be removed by a manufacturing process of an aluminum tube. The major parameters on the coating quality of an OPC drum are the impurities of an aluminum tube such as silicon, oxygen, calcium, carbon, sulphur, chlorine, and others. These impurities may be removed by an ingot molding, extrusion and drawing, quality control, and packing processes with a strict manufacturing technology.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.285.2-286
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• 2003

Analysis of illicit methamphetamine samples seized in Korea is discussed. The samples are extracted with the small portion of ethyl acetate under neutral conditions and the extracts are analyzed by GC-MS. Several impuritiy peaks are found in each chromatrogram. Eight compunds (1,2-Dimethyl-3-phenylaziridine, amphetamine oxime, ephedrine, N-formylmethamphetamine, N-acetylmethamphetamine, acetylephedrine, 3,4-dimethyl-5-phenyl-2-oxazolidone, methamphetamine dimer) are identified impurities in illicit methamphetamine and the identity of the impurity is conformed synthesis. (omitted)

• Journal of the Korean Geophysical Society
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• v.4 no.4
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• pp.251-256
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• 2001

Korean natura1 zeolite with fe1dspar and illite as impurities was purified by an air c1assification method. X-ray powder diffraction ana1yses showed that the air c1assification effectively separated zeolite and impurities, and reduce the amount of impurity of the natura1 zeolite. The zeolite with air c1assification was treated with 1N NaOH solutions at temperatures at 100, 150, 200 ℃ for 17hours. The obtained hydrotherma1 treatment of phase change to philli1site and ana1cime from mordenite and clinopti10lite.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.43.2-43.2
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• 2011

Minority Carrier recombination should be suppressed for high efficiency solar cells. However, impurities in the silicon bulk region deteriorate the minority carrier lifetimes, causes conversion efficiency drop. In this study, we introduced phosphorus external gettering for silicon heterojunction solar cell substrates. Gettering was undergone at 750, 800, 850 and $900^{\circ}C$ in furnace for 30 minutes. Bulk lifetimes and calculated diffusion length were improved. We applied phosphorus gettering to silicon heterojunction solar cells. Gettered group and ungettered group were used as substrate of silicon heterojunction solar cells. After fabrication, characteristics of solar cells were analyzed. The results were observed to see the enhancement of substrate quality which directly connects with solar cell properties.

• Nuclear Engineering and Technology
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• v.13 no.4
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• pp.237-244
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• 1981

The preliminary concentration of trace elements in uranium dioxide using an anion exchange resin is presented for neutron activation analysis. The uranyl solution in sulfuric acid is adjusted to the acidity of about pH 2.7 and loaded on a column of the anion exchange resin. An appropriate volume of eluates obtained from the column shows good recoveries of trace elements. By combining this preconcentration with a radiochemical separation scheme, which was developed for the determinations of impurities in aluminum, it is possible to determine 21 trace elements in reactor grade uranium dioxide.