• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.4
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• pp.309-317
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• 2005

A study on the separation of $^{99}Tc,\;^{94}Nb,\;^{55}Fe,\;^{90}Sr\;and\;^{59/63}Ni$ in various radioactive wastes discharged from nuclear power plants has been performed for a use in their quantification which is indispensible for the evaluation of the radionuclide inventory Ni was recovered along with Ca, Mg, Al, Cr, Ti, Mn, Ce, Na, K, and Cu through the sequential separation procedure of Re(as a surrogate of $^{99}Tc$), Nb, Fe and Sr by anion exchange and Sr-Spec extraction chromatography. In this research, chemical separation of Ni from the co-existing elements was investigated by cation exchange and Ni-Spec extraction chromatography. Precipitation behaviour of Ni and the co-existing elements with dimethylglyoxime(DMG) was investigated in ammonium $citrate/ethanol-H_2O$ and tartaric $acid/acetone-H_2O$ in order to purify separated Ni fractions and to prepare $^{59/63}Ni$ source for the radioactivity measurement using a gas proportional counter. Recovery of Ni separated through ion exchange chromatographic separation procedure was $92.1\%$ with relative standard deviation of $0.9\%$. In addition, recovery of Ni with DMG in the tartaric $acid/acetone-H_2O$ was $85.6\%$ with relative standard deviation of $1.9\%$.

• Korean Journal of Environmental Agriculture
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• v.19 no.1
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• pp.62-66
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• 2000

This study was conducted to determine the soil chemical properties and microbial flora of platycodon and their effect on rhizome rot incidence. Sampling sites were Keochang 4, Kimhae 7, Haman 6, Chinju 6 and Koseong 3 fields in Kyongnam province and Hongcheong 6 fields in Kangwon province. The root disease incidence rate was in the order of Haman 56.8%, Hongcheon 52.5%, Kimhae 36.7%, Koechang 35.3%, Chinju 32.3%, Koseong 30.0%. The yield at the Chinju 36.17 Mg/ha was higher than that of Koseong 25.00 Mg/ha, Kimhae 13.57 Mg/ha, Koechang 11.75 Mg/ha, Haman 9.50 Mg/ha, Hongcheon 5.24 Mg/ha. The soil K, $NH_4-N$ content and EC value of injury root were higher than those of normal root. The root CaO content was positively correlated with yield $Y=20505X-367.9(R^2=0.129^{\ast})$. The Fe and Zn content of normal root were higher than those of injury root, while the T-N, $P_2O_5$ and $K_2O$ content of normal root were lower than those of injury root. The population of bacteria, actinomycetes and bacteria/fungi ratio increased in soil of normal root, but that of fungi decreased.

• Journal of the Korean Magnetics Society
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• v.15 no.4
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• pp.226-230
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• 2005

In this research, magnetic properties and annealing effects of the spin valve structures were investigated, which have Ta underlayer deposited with Ar and $N_2$ gas mixture. Also, TaN underlayer as a diffusion barrier and the substrate were investigated. The structure of the spin valve was Si($SiO_2$)/Ta(TaN)/NiFe/CoFe/Cu/CoFe/FeMn/Ta. Deposition rate was decreased and resistivity and roughness of the TaN films were increased as the $N_2$ gas flow was increased. The XRD results after high temperature annealing showed that Silicides were created in Si/Ta layer, but not in Si/TaN layer. Magnetoresistance ratio (MR) and exchange coupling field ($H_{ex}$) were decreased when the $N_2$ gas flow was increased over 4.0 sccm. The MR of the spin valves with Ta and TaN films deposited with up to 4.0 sccm of $N_2$ gas flow was increased about $0.5\%$ until the annealing temperature of up to $200^{\circ}C$ and then, decreased. TaN film deposited with 8.0 sccm of $N_2$ gas flow showed twice the adhesion of the Ta film. The above results indicate that with 3.0 sccm of $N_2$ gas flow during the Ta underlayer deposition, the magnetic properties of the spin valves are maintained, while the underlayer may be used as a diffusion barrier and the adhesion between the Si substrate and the underlayer is increased.

• Korean Journal of Materials Research
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• v.21 no.2
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• pp.73-77
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• 2011

Specific heat of a crystal is the sum of electronic specific heat, which is the specific heat of conduction electrons, and lattice specific heat, which is the specific heat of the lattice. Since properties such as crystal structure and Debye temperature do not change even in the superconducting state, the lattice specific heat may remain unchanged between the normal and the superconducting state. The difference of specific heat between the normal and superconducting state may be caused only by the electronic specific heat difference between the normal and superconducting states. Critical temperature, at which transition occurs, becomes lower than $T_{c0}$ under the influence of a magnetic field. It is well known that specific heat also changes abruptly at this critical temperature, but magnetic field dependence of jump of specific heat has not yet been developed theoretically. In this paper, specific heat jump of superconducting crystals at low temperature is derived as an explicit function of applied magnetic field H by using the thermodynamic relations of A. C. Rose-Innes and E. H. Rhoderick. The derived specific heat jump is compared with experimental data for superconducting crystals of $MgCNi_3$, $LiTi_2O_4$ and $Nd_{0.5}Ca_{0.5}MnO_3$. Our specific heat jump function well explains the jump up or down phenomena of superconducting crystals.

• Journal of the Mineralogical Society of Korea
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• v.16 no.1
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• pp.19-31
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• 2003

Chemical composition, crystal structure, refractive index, specific gravity, color, and luster were studied fur pyrope-almandine series garnets. The main coloring agents determining the reddish or brownish garnets were also investigated. It was also examined if there is any relationship between mineralogical properties with respect to the various chemical compositions in the solid solution, in the hope to figure out the existing classification values of R.I. and S.G. using gem- testing facilities to distinguish pyrope from almadine. It was found that 17 out of the 24 specimens belong to pyrope and the rest almandine. R.I. of pyrope goes up to 1.77 and that of almandine is higher than the value.5.5. of pyrope reaches to 3.88 and that of almandine is greater than the value of pyrope. X-ray diffraction data revealed that pyrope-almandine garnets are isometric with space group Ia3d, and also show that the variation of cell parameters are not significant enough to parallel with the chemical compositions of the series. R.I. and S.G. increase with FeO content. Fe and Mn are most responsible to the red-purple and orange coloration of the specimens, respectively. Both zircon and rutile crystals are most common inclusions in the reddish stones.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.249-257
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• 2005

Garnet is one of the major minerals down to the top of lower mantle approximately 660 km with spinel and pyroxenes. Garnet transforms into perovskite and corundum in the lower mantle, however its sequence is still in controversy. We measured the compressibility of a natural almandine at high-pressure up to 62 CPa using Mao-Bell type diamond anvil cell (DAC) at room temperature. Chemical formula of the specimen is ($Fe_{2.52}Ca_{0.21}Mg_{0.18}Mn_{0.12})Al_{2.23}Si_{2.97}O_{12}$. Results of this compression study are as follows: a : $10.175\;{\AA}$, V : $1251.16\;{\AA}^{3}$, $D_{x}$ : $5.265\;g/cm^{3}$ at 62 GPa; bulk modulus is 156 GPa using Birch-Murnaghan equation of state (EoS) with a fixed $K_{0}\;'$ of 4. This study would be the first time attempt accomplished with the high pressure DAC using synchrotron radiation at the Pohang Light Source (PLS) in Korea.

• Resources Recycling
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• v.31 no.2
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• pp.20-32
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• 2022

This study implemented a chelating agent (Ethylenediaminetetraacetic acid, EDTA) in purification to obtain high-purity vanadium pentoxide (V₂O₅) for use in VRFB (Vanadium Redox Flow Battery). V₂O₅ (powder) was produced through the precipitation recovery of ammonium metavanadate (NH₄VO₃) from a vanadium solution, which was prepared using a low-purity vanadium raw material. The initial purity of the powder was estimated to be 99.7%. However, the use of a chelating agent improved its purity up to 99.9% or higher. It was conjectured that the added chelating agent reacted with the impurity ions to form a complex, stabilizing them. This improved the selectivity for vanadium in the recovery process. However, the prepared V₂O₅ powder exhibited higher contents of K, Mn, Fe, Na, and Al than those in the standard counterparts, thus necessitating additional research on its impurity separation. Furthermore, the vanadium electrolyte was prepared using the high-purity V₂O₅ powder in a newly developed direct electrolytic process. Its analytical properties were compared with those of commercial electrolytes. Owing to the high concentration of the K, Ca, Na, Al, Mg, and Si impurities in the produced vanadium electrolyte, the purity was analyzed to be 99.97%, lower than those (99.98%) of its commercial counterparts. Thus, further research on optimizing the high-purity V₂O₅ powder and electrolyte manufacturing processes may yield a process capable of commercialization.

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.123-129
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• 1999

Initial electrochemical characteristics of $LiCoO_2$ electrode for lithium ion battery with various content of super s black as conductive material were evaluated through the charge/discharge with the potential range of 4.3V to 2.0V versus $Li^+/Li^+$. The rate of C/4 and C/2 by the 3 electrode test cell composed with an electrolytic solution of 1 mol/l $LiPF_6/EC+DEC(1:3\;by\; weight)$. Lithium was used as reference electrode. High impedance charge behavior was observed at early stage of charge. In the case of $3\%w/w$ of super s black as conductive material, the specific resistance of the high impedance releasing was $3.82\;{\Omega}\;{\cdot}\;g-LiCoCo_2$ at the current density of $0.5 mA/cm^2$, which corresponds 7 times of the specific resistance of electrode $(0.728 g-LiCoO_2)$. At second charge, the specific resistance of the high impedance releasing was 63 mn · g-Lico02, which corresponds 12eio of the specific resistance of electrode and only $1.7\%$ of that of the first charge. The first charge and discharge specific capacities at C/4 rate were 160-161 and $153\~155mAh/g-LiCoO_2$, respectively, to lead $95.4\~96.4\%$ of coulombic efficiencies and ca. $6 mAh/g-LiCoO_2$ of initial irreversible specific capacity. Specific resistance at the end of charge and rest showed low value at content of super s black between 2 and $7\%w/w$, which agreed with characteristics of irreversible specific capacity. Capacity densities were reduced by the increasing the content of conductive material. They were 447 and 431mAh/ml when 2 and $2.9\%w/w$ of super s black were used, respectively, at the rate of C/4.

• Economic and Environmental Geology
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• v.30 no.5
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• pp.443-450
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• 1997

The main purpose of this study is to investigate mineralogical and chemical changes during natural weathering, and assess the mobility of major and trace elements. Yongwol power plant utilize anthracite coal which is mainly composed of illite, kaolinite, pyrophyllite and quartz in mineralogy. Coal and coal-derived fly ash samples were sampled by the electrostatic precipitator in Yongwol coal-fired power plant in Korea. Short term weathered fly ash were also collected in ash disposal mound, and two profile soil samples were taken from an ash near the power plant. Amorphous materials are the main component of the fly ash, and mullite, quartz, magnetite and heamatite are present in all coal-derived fly ash. In chemistry, Si and Al are the most abundant elements of the total content. The ash samples were fractionated into upper $90{\mu}m$ and under $45{\mu}m$ size. Finer particles show higher concentrations in metal contents including Co, Cr, Cu, Ni, V, Zn and Pb. Concentration of Zn and Pb are nearly 4 times higher concentration in the finer particles. For the profile samples, the concentrations of $SiO_2$, $Na_2O$, MgO and $K_2O$ generally show increasing trends with depth, whereas those of $Fe_2O_3$ and $TiO_2$ appear to decrease with depth. Content of MnO does not show any specific depth trend. For the trace elements, Co, Cu, Ni and V show increasing concentrations with depth.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.44-44
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• 2008

GdBCO coated conductor have been fabricated using reactive co-evaporation. The batch type co-deposition system was specially designed and was named EDDC (evaporation using drum in dual chamber) that is possible to deposit superconducting layer with optimum composition ratio of materials at temperature over $700^{\circ}C$ and several mTorr of oxygen. The IBAD-MgO substrate with the architecture of LaMnO3(LMO)/IBAD-MgO/Hastelloy was used for coated conductor. In this study, GdBCO superconducting layer was deposited on IBAD-MgO substrate at optimal oxygen partial pressure (pO2) and deposition temperature. After fabrication of GdBCO coated conductor, critical current density was measured by 4-probe method. Surface morphology and texture of GdBCO coated conductors were analyzed by the SEM and XRD, respectively.