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- Author or Editor: Y. Choi x
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Abstract
We establish strong limsup theorems related to the law of the iterated logarithm (LIL) for finite dimensional Gaussian random fields by using the second Borel-Cantelli lemma.
Abstract
This paper establishes the general moduli of continuity for l ∞-valued Gaussian random fields {X(t):= (X 1(t),X 2(t), h.), t ∈ [0, ∞) N } indexed by the N-dimensional parameter t:= (t 1,…,t N ), under the explicit condition yielding that the covariance function of distinct increments of X k (t) for fixed k ≧ 1 is positive or nonpositive.
Abstract
Supported liquid membrane containing crown ether (DC18C6) and dinonylnaphthalenesulfonic acid (DNNS) is proposed for separation and preconcentration of strontium in an aqueous environmental sample. The effects of carriers in membrane on permeability and selectivity of Sr2+ were characterized. Crown ether has a key role in the selective transport of strontium ion while DNNS facilitates the transport of both Sr2+ and Ca2+. A strontium ion can be selectively transported to an acidic strip solution against its concentration gradient across the membrane. This SLM can be used as an efficient method for separation and preconcentration of strontium in a neutral aqueous sample.
Abstract
Elution chromatographic separation of lithium isotopes was carried out with aminobenzo-15-crown-5 bonded merrifield resin. This resin have a capacity of 0.24 meq/g dry resin. By column chromatography using 1.0M NH4Cl solution as an eluent, a single separation factor 1.026 was obtained from the elution curve and isotope ratios according to the Glucckauf theory. The heavier isotope, 7Li was concentrated in the resin phase, while the lighter isotope, 6Li enriched in the solution phase.
Abstract
Correction equations of the coincidence-summing effect for efficiencies of HpGe detector based on the decay scheme were developed by considering the summing up to triple coincidence. The correction equations which do not dependent on the kind of the Ge detector are very useful for efficiency calibrations of a Ge detector in the energy region from 60 to 400 keV by using75Se radionuclide even with very short source-to-detector distances.
This study aimed to develop a chromatographic method to quantitatively determine phenol in fish tissues. This method involves solvent extraction of acidified samples, followed by derivatization to phenyl acetate and analysis with gas chromatography coupled with mass spectrometry (GC–MS). Phenol in a representative tissue sample (belly, gill, or renal tubules), which was homogenized with 2 N sulfuric acid, was extracted with ethyl acetate and derivatized to phenyl acetate using acetic anhydride and K2CO3 in water. An n-butyl acetate extract was injected into the GC–MS. The linearity (r 2) of the calibration curve was greater than 0.996. The analytical repeatability, which is expressed as the relative standard deviation, was less than 6.14%, and the recovery was greater than 96.3%. The method detection limit and the limit of quantitation were 8.0 μg/kg and 26 μg/kg, respectively. The proposed method is also applicable to the analysis of other biological tissues for phenol and its analogs, such as pentachlorophenol.
Abstract
The Korea Atomic Energy Research Institute (KAERI) has launched a decommissioning program of the uranium conversion plant. The sludge waste, which was generated during the operation of the plant and stored in the lagoon, was characterized for the development of the treatment process. The physical properties were measured and chemical compositions and radiological properties analyzed. The main compounds of the sludge were ammonium nitrate, sodium nitrate, calcium nitrate, and calcium carbonate. All heavy radioactive elements such as uranium, thorium and 226Ra were precipitated and deposited at the bottom, and were not dissolved in the concentrated nitrate solution. A possible flow-scheme for processing is presented.
Abstract
Depth distribution of239,240Pu and137Cs in the soils of South Korea have been studied. The average accumulated depositions were estimated roughly to be 54.8±32.1 Bq·m–2 for239,240Pu, 1.6±1.0 Bq· ·m–2 for238Pu and 1982.8±929.1 Bq·m–2 for137Cs. The activity ratios of239,240Pu/137Cs in soils were found to be in the narrow range of 0.0153 to 0.0364 with a mean value of 0.0230±0.006. The concentrations of239,240Pu and137Cs in soils decrease exponentially with increasing the soil depth. A significant correlation was found between the concentration of239,240Pu and that of137Cs. The activity ratios of239,240Pu/137Cs tend to increase slightly with increasing soil depth.
Abstract
A study on the separation of lithium isotope was carried out with N4O azacrown ion exchange resin. The lighter6Li isotope concentrated in the solution phase, while the heavier7Li isotope is enriched in the resin phase. Upon column chromatography (0.3 cm I.D.×15.5cm height) using 0.5M NH4Cl as an eluent, single separation factor, α=1.00127 was obtained.
