• Journal of radiological science and technology
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• v.13 no.2
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• pp.43-49
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• 1990

[ $^{111}$ ]In has wide applications in nuclear medicine for labelling and in-vivo distribution studies. A method is developed for the production of carrier free $^{111}$In using the reaction $^{nat.}Cd(p,\;xn)$ $^{111}$In with MC-50 cyclotron. Carrier free $^{111}$In was separated from the irradiated metallic cadmium by liquid-liquid extraction and cation exchange chromatography. The yield of $^{111}$In at EOB is $0.8mCi/{mu}\;Ahr$ and the nuclidic purity is over 99%. $^{111}In-DTPA\;and\;^{111}In-bleomycin$ were prepared for medical study.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.3
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• pp.246-251
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• 2017

To fabricate a hydrocarbon polymer electrolyte composite membrane incorporated with Pt nanoparticle, the polymer electrolyte membrane made of a sulfonated-fluorinated hydrophilic-hydrophobic block copolymer (SFBC) and sulfonated poly (ether ether ketone) (SPEEK) blend in the wight ratio of 1 : 1 was synthesized, and a simple drying process was used in order to incorporate Pt nanoparticle into the SFBC/SPEEK film by reducing platinum (II) bis (acetylacetonate), Pt $(acac)_2$. The distribution of the Pt nanoparticles was observed by transmission electron microscopy (TEM), and mechanical and thermal properties were tested by universal testing machine (UTM) and thermogravimetry analyzer (TGA). Cation conductivity, ion exchange capacity (IEC) and I-V characteristics were estimated.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.345-349
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• 2000

To easily separate chitosanoligosaccharides by size exclusion, an coencapsulating technology of substrate and enzyme was developed. The membrane was composed of alginate and a divalent cation such as calcium. Chitosan and chitosanase were enveloped in this membrane and the product released to medium by size exclusion. The capsule was stabilized in a 2% acetic acid solution (pH 5.0) containing 0.145 M CaCO$_3$. The leakage of substrate caused by the agitation speed was controlled by increasing alginate and CaCO$_3$concentrations. The lower limit of the alginate concentration and the agitation speed were 0.5% and 49rpm, respectively. Membrane thickness and capsule diameter were 10$\mu\textrm{m}$ and 2.5mm, respectively. By TLC analysis, the composition of chitosanoligosaccharides were mainly 3-6 mers. The molecular weight distribution of the released oligosaccharides ranged from 262 to 3624 Da by GPC.

• Journal of Magnetics
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• v.16 no.2
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• pp.134-139
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• 2011

Magnetic properties of highly zinc-substituted manganese ferrites are discussed on the basis of cation distribution. High throughput neutron powder diffractometry indicates that the prepared samples possess a nearly normal spinel structure, where the substitution of nonmagnetic zinc ions mainly causes the dilution of magnetic ions in the A-sublattice and consequently affects bond-randomness in the B-sublattice. On the other hand, the estimated occupancy of manganese ions in the B site indicates that random anisotropy effects due to local Jahn-Teller distortions gradually weaken with the substitution. Bulk magnetometry indicates that the substitution smears the transition from a paramagnetic phase to a soft-magnetic phase. Furthermore, at lower temperatures, such a soft-magnetic phase is destabilized and a magnetic glassy state appears. These features of the magnetic properties of dilute spinel ferrites are discussed from the viewpoint of the above-mentioned various types of disorders.

• Journal of Radiation Protection and Research
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• v.30 no.4
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• pp.167-174
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• 2005

The concentrations of natural and artificial radionuclides in soil and gamma ray dose rate in air at 233 locations in Korea have been determined. The national mean concentrations of $^{232}Th,\;^{226}Ra,\;^{40}K,\;^{137}Cs\;and\;^{90}Sr$ in soil were $60{\pm}31,\;33{\pm}14,\;673{\pm}238,\;35{\pm}9.3\;and\;5.0{\pm}3.4\;Bq\;kg^{-1}$, respectively. The mean gamma-ray dose rate at 1 m above the ground was $7918\;nGy\;h^{-1}$. $^{137}Cs$ concentration had highly significant correlation with organic matter content and cation exchange capacity. $^{90}Sr$ concentration had slightly coherent with pH. The results have been compared with other global radioactivity and radiation measurements.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.198-202
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• 1998

We have studied $Al_xFe_{3-x}O_4$ produced by direct composition method using X-ray diffraction and Mssbauer spectroscopy. The cation distribution for $Al_xFe_{3-x}O_4$ was determined by the ratio of sub-spectra absorption area. The charge state of Fe atoms in octahedral site(B-site) is $Fe^{2.5+}$ based on electron hopping, $Fe^{2+}$ ↔ $(Fe^{3+},Al^{3+})$ without dependency of substituted Al amounts.

• Bulletin of the Korean Chemical Society
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• v.20 no.8
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• pp.939-942
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• 1999

The tie lines delineating ion-exchange equilibria between NiFe2O4-NiCr2O4 spinel solid solution and Fe2O3-Cr2O3 corundum solid solution were determined at 900, 1000, and 1200 ℃ by electron microprobe and energy dispersive X-ray analysis of oxide phases, using the flux growth technique. Activities of the spinel components were calculated from the tie lines, assuming Temkin's ideal mixing in the corundum solid solution. The spinel phase could be expressed by a regular solution with negative deviations from ideality. The Gibbs free energies of mixing for spinel solid solution were discussed in terms of the cation distribution model, based on site preference energies and assuming random mixing on both tetrahedral and octahedral sites.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.678-681
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• 1993

The new ternary phase $UP_2S_6$ has been prepared and structurally characterized. The compound is isostructural with $ZrP_2S_6$ and $ThP_2S_6$ but is different from $TiP_2S_6$. The structure has been determined by a single crystal X-ray diffraction technique. $UP_2S_6$ crystallizes in the the tetragonal system $({C^2}_{4h}-P4_2/m,\;a=6.797(7)\;{\AA},\;c=9.738(12)\;{\AA})$ with two formula units in the unit cell. The structure can be described in terms of $U^{4+}$ and ${P_2S_6}^{4-}$ ions. This hexathiohypodiphosphate anion $({P_2S_6}^{4-})$ has ideally staggered conformation. The $U^{4+}$ cation is coordinated by 8 sulfur atoms in a slightly distorted dodecahedral geometry (42m). The distribution of sulfur atoms is very well optimized for this geometry.

• Korean Journal of Environment and Ecology
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• v.30 no.6
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• pp.929-938
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• 2016

This study reviewed the external morphological characteristics of a rare species, Exochorda serratifolia S.Moore, in South Korea through a comparison of its previous records. Also, a distribution map of this species was made using previous data on flora and voucher specimens. Furthermore, the soil characteristics of Exochorda serratifolia S.Moore was analysed in order to determine the correlation between external morphological features and soil characteristics. At the study sites, soil organic matter, total nitrogen, available phosphates, exchangeable potassium, exchangeable calcium, exchangeable magnesium, cation exchange capacity and soil pH were found to be in the ranges of 3.25-29.83%, 0.15-1.14%, 3.0-156 mg/kg, $0.39-1.49cmol^+/kg$, $2.48-38.07cmol^+/kg$, $0.77-18.29cmol^+/kg$, $7.3-23.0cmol^+/kg$ and 4.6-7.1 respectively. The soil condition surrounding the population of Exochorda serratifolia S.Moore in Mt. Ap-san (Daegu) was found to have higher percentages of organic matter, total nitrogen, and cation exchange capacity than the soil condition of other populations. Moreover, the length of inflorescence and the number of flowers in this population were significantly higher than the populations studied in other areas (P < 0.001). We also identified a significant correlation between genetic, geographic distance and several morphological characteristics. A comprehensive review of various data on Exochorda serratifolia S.Moore such as external morphological characteristics, genetic structure, growth conditions, vegetation properties, and environmental characteristics is required to understand its growth characteristics and conserve this rare species.

• Analytical Science and Technology
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• v.23 no.6
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• pp.566-571
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• 2010

This paper describes the sorption behaviors of aqueous uranium ions on the K-birnessite. K-birnessite was synthesized by adding a concentrated HCl to an aqueous solution of $KMnO_4$. Physicochemical characteristics of the K-birnessite, such as structure, specific surface area and surface charge, were investigated. K-birnessite is a layered material and the $K^+$ ions exist in the interlayer of layered K-birnessite. BET specific surface area of the K-birnessite was 38.30 m2/g. The surface charge of K-birnessite was $-1.65\;C/m^2$ at pH 5.00 and ionic strength of 0.010 M $NaClO_4$, at which the sorption experiments of uranium ions were carried out. Uranium ions were incorporated into the interlayer of the K-birnessite by cation-exchange reaction with $K^+$ ions, and the distribution coefficient is quite similar to those of common ion-exchange materials. The results might be applicable in the retardation of migration of radioactive materials from the underground disposal site of high-level radioactive waste.