• Analytical Science and Technology
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• v.22 no.6
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• pp.519-523
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• 2009

$^{129}I$ is especially one of the most harmful radioactive elements because of its long half-life ($t_{1/2}$=$1.7{\times}10^7$ yr). The efficient removal of iodide ($I^-$) and iodate (${IO_3}^-$) in a aqueous solution by adsorption using activated alumina and activated carbon was studied. The removal efficiency was over 99% for iodide ion with silver treated basic alumina and iodate ion with acidic alumina or silver treated acidic alumina without any chemical addition or physical treatments.

• Economic and Environmental Geology
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• v.38 no.4 s.173
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• pp.451-462
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• 2005

In order to examine the extent of environmental contamination at abandoned Samsanjeil Cu mines in Kosung-kun, Kyeongsangnam-do, we have investigated the contaminations and mobility of toxic trace elements from mine wastes including about 280,000 tonnages of tailings by chemical experiments (total extraction, partial extraction by 0.1N HCI and sequential extraction procedure). Total concentrations of trace elements showed that Cu, As, Co, Zn, Pb, and Cd concentrations in tailings were 14.0, 3.6, 3.1, 2.1, 2.1 and 1.6 times greater than those in background soil, respectively. From the proportion of metals bound to the exchangeable and carbonate fractions, the comparative mobility of metals decrease in order of $Zn(29.0\%)>Cu(12.3\%)Pb(9.6\%)>Cd(3.0\%)>As=Co(0.0\%)$. Based on the concentrations, chemical speciations of tailings, waste rock and nearby soil, it was revealed that Cu and Zn were the most possible elements to contaminate the surrounding environment in Samsanjeil mine area. In addition, the tailings had total trace metal concentrations below Dutch guideline values except Cu, and they might not affect adverse impact on environment.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.121-127
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• 2015

Nanotubular $TiO_2$ prepared by electrochemical anodization has been significantly used for various applications due to high aspect ratio structures showing a high chemical stability. Morphological properties of nanotubular titanium oxide are easily tailored by adjusting types and compositions of electrolyte, pH value, applied voltage, temperature and anodization time. Since their catalytic properties can be enhanced by doping foreign elements into $TiO_2$, metal as well as non-metal elements are doped into $TiO_2$ nanotubes using different methods. For example, single anodization, thermal annealing, precipitation, and electrochemical deposition have been applied to simplify the doping process. In this review, anodization of Ti to produce $TiO_2$ and doping methods will be discussed in detail.

• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.56-66
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• 2013

The gas production plants supply the inert gas to production plants for maintaining safe operation and also supply combustible, flammable, explosive and toxic gases as functions of basic materials needed for producing chemical goods. In addition, gas plants need to be safe and reliable operation because they are operated under high temperature, high pressure, cryogenic and catalytic reactions. As these plants have a complex process in operation, there has been a risk that major industrial accidents such as a fire, explosion and toxic gas released, also risks of asphyxiations by inert gases and burns caused by high temperature and cryogenic substances. This study is to carry out the semi quantitative risk assesment method which is the generic risk analysis (GRA). This method is applied to air separation unit(ASU) to identify its initial risk, safety barriers, residual risk and elements important for safety(EIS). The result of this study, suggested the management tools and procedures of implementation for EIS management.

• Analytical Science and Technology
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• v.7 no.3
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• pp.301-313
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• 1994

X-Ray Photoelectron Spectroscopy(XPS) and Rutherford Backscattering Spectroscopy(RBS) are used for the analysis of additives, examination of chemical structure and determination of identity with qualitative and quantitative analysis of surface elements, binding energy level and depth profiling in the surface. We analyzed surface of polyethylene, acrylonitrile butadien rubber, polypropylene, glass, fiber and paper treated with $XeF_2$ or C-F plasma by XPS and RBS. It was found that fluoro element was penetrated to sample surface and the distribution of surface elements are different than untreated samples.

• Spatial Information Research
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• v.10 no.2
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• pp.201-213
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• 2002

Chemical analyzes were carried out the samples from roadsides of the Gwangju city. The purpose of this research is to investigate the concentrations and distribution patterns of heavy metals due to urbanization and industrialization in the Gwangju city This study area is not significantly contaminated based on the concentrations of Cd, Cu, Fe, Mn, Pb and Zn. However, the concentrations of the chemical elements analyzed are locally higher than those of serious contamination level indicated by Ministry of environment. The dust pH is in the rage of 5.60-7.09 and was generally neutral, and there are no difference in pollution area and nonpollution area. Chemical analyses utilized are dilution by 0.1N HCl. In result of analysis by the method using 0.1N HCl, concentrations of Cd and Cu are a little high in Gwangchondong of Seo-Gu. Concentrations of Mn and Pb are a little high in Buk-Gu and Nam-gu, and Concentrations of Zn are generally higher than average of soils. Zn, in the study area, keeps polluting greatly as Zn concentration of average is 150.9ppm. All of P.I values are lower than 1, it means heavy metal pollution is not serious.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.720-726
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• 1992

Multivariate analysis such as factor analysis was applied to interpret multivariate data, which were obtained from the overlapped X-ray fluorescence spectra. X-ray fluorescence spectra of 11 reference samples were obtained by the wavelength dispersive spectrometer at a specified range of angle such as $33.50∼34.50^{\circ}$. The data matrix was made from the spectra of 8 samples. The results of abstract factor analysis gave three factors. By the target testing with 8 elements contained in the reference samples, the three factors were found to be Pb, As and Cu. The concentration of these elements in the test samples was determined by target transformation factor analysis regardless overlapping individual peaks.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.1
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• pp.23-32
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• 1999

Deposition is one of the important removal mechanisms for the ambient aerosol, and it also leads to adverse environmental and economic impacts. The purpose of this study was to investigate chemical compositions and spatial distributions of fall-out aerosols. A total number of 340 samples were collected at 35 sampling sites in Suwon area from January to November, 1996. Twelve inorganic elements (Al, Ba, Cd, Cr, K, Pb, Sb, Zn, Cu, Fe, Ni, and V) and eight ionic components ($F^-$, Cl, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $NH_4^+$, $Mg^{2+}$, and $Ca^{2+}$) were analyzed by AAS and IC, respectively. The monthly variation showed that the flux of fall-out particles was increased in the spring season(March, April, and May) and decreased from August to October. Arithmetic mean flux of fall-out particles was 176.8 kg/$ extrm{km}^2$/day during the study period. The fluxes of each chemical species were $SO_4^{2-}$ 12.414, $Ca^{2+}$ 7.369, $NO_3^-$ 5.812, $Cl^-$ 3.566, $NH_4^+$ 3.176, Fe 3.107 kg/$\textrm{km}^2$/day, and so on. By using a kriging analysis, spatial distribution pattern of those fluxes was intensively studied. Total fluxes estimated in Suwon city were 8424.72t/y of fall-out particles, 519.27t/y of $SO_4^{2-}$, 336.79t/y of $Ca^{2+}$,267.34 t/y of $NO_3^+$, 155.36t/y of $Cl^-$, 147.79t/y of Fe.

• Journal of The Korean Astronomical Society
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• v.52 no.3
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• pp.57-69
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• 2019

We present an analysis of the chemical abundances and kinematics of six low-mass dwarf stars, previously claimed to be candidate hypervelocity stars (HVSs). We obtained moderate-resolution (R ~ 6000) spectra of these stars to estimate the abundances of several chemical elements (Mg, Si, Ca, Ti, Cr, Fe, and Ni), and derived their space velocities and orbital parameters using proper motions from the Gaia Data Release 2. All six stars are shown to be bound to the Milky Way, and in fact are not even considered high-velocity stars with respect to the Galactic rest frame. Nevertheless, we attempt to characterize their parent Galactic stellar components by simultaneously comparing their element abundance patterns and orbital parameters with those expected from various Galactic stellar components. We find that two of our program stars are typical disk stars. For four stars, even though their kinematic probabilistic membership assignment suggests membership in the Galactic disk, based on their distinct orbital properties and chemical characteristics, we cannot rule out exotic origins as follows. Two stars may be runaway stars from the Galactic disk. One star has possibly been accreted from a disrupted dwarf galaxy or dynamically heated from a birthplace in the Galactic bulge. The last object may be either a runaway disk star or has been dynamically heated. Spectroscopic follow-up observations with higher resolution for these curious objects will provide a better understanding of their origin.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.383-383
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• 2009

Silicon is commercially prepared by the reaction of high-purity silica with wood, charcoal, and coal, in an electric arc furnace using carbon electrodes, so called the metallurgical refining process, which produces ~98% pure Si (MG-Si). This can be further purified to solar grade silicon (SoG-Si) by various techniques. The most problematic impurity elements are B and P because of their high segregation coefficients. In this study, we explored the possibility of the using Cat-CVD for Si purification. The existing hot-wire CVD was modified to accommodate the catalyzer and the heating source. Mo boat (1.5 cm ${\times}$ 1 cm ${\times}$ 0.2 cm) was used as a heating source. Commercially available Si was purchased from Nilaco corporation (~99% pure). This powder was kept in the Mo-boat and heated to the purification temperature. In addition to the purification by cat-CVD technique, other methods such as thermal CVD, plasma enhanced CVD, vacuum annealing was also tried. It is found that the impurities are reduced to a great extent when treated with cat-CVD method.