• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.67-79
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• 2003

An approximation for the bias in lag window estimators of the degree of differencing in fractionally integrated time series models is derived. The expression obtained is compared with the observed bias from simulations for various windows.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.101-112
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• 2007

In this paper, by using fractional power of operators and Sadovskii fixed point theorem, we study the controllability of abstract neutral functional integrodifferential systems with infinite delay. As application, an example is provided to illustrate the obtained results.

• Journal of Korea Foundry Society
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• v.11 no.4
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• pp.303-313
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• 1991

The Purification mechanism of high purity aluminum was studied through the variation of stirring speed and coolant flow rate in the stirring method. In the stirring method the degree of purification was changed as the following factors;the variation of diffusion boundary layer thickness the variation of growth rate and the solute concentration of the residual melt. The concentration of Fe and Si was decreased as the stirring speed and the radial distance increased. In a high stirring speed of 2000rpm with unidirectional stirring mode, the uniformity of solutes was obtained. On the other hand, the purification of Si was done by the combinations of stirring method, fractional melting and acid leaching. In the case of Si purification, the centrifugal force developed in the melt acted as the significant purification factor. It was possible to obtain the purified 3N grade Si crystal after the complete elimination of residual aluminum by fractional melting and acid leaching.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.4
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• pp.185-196
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• 1991

A laterally-averaged X-Z numerical model with transformed coordinates is developed to analyze the salinity dispersion in estuaries. Gravitational term, salinity variations with respect to the water depth. and re-evaluation of , salinity boundary condition are examined. Especially. the improvements in stability and accuracy of the numerical algorithm are made by adopting the fractional step method for the dispersion term of the governing equation. The model being applied to the Keum River Esturary, physical and numerical properties of Manning's n and dispersion coefficients are analyzed. Salinity intrusion into the river, influence of upstream river inflows, and salinity distribution for spring/neap tide are also examined.

• Journal of Industrial Technology
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• v.20 no.A
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• pp.57-62
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• 2000

This experiment was done to investigate the leaching and adsorption properties of heavy metals on porphyry. The comparison with respect to the leachability of heavy metals from porphyry between the Korea Standard Leaching Test (KSLT) and the Toxicity Characteristic Leaching Procedure (TCLP) was carried out. The fractional composition of leachate and the total concentration of heavy metal of porphyry were studied through Sequential Extraction Procedure (SEP) and EPA Method 3050. Adsorption experiment of porphyry has pointed out that the optimum dosage of porphyry for 50ppm Pb was over 10g/L, the effective particle size for absorption was below 200 mesh and the optimum pH was about 7. From the Freundlich' adsorption equation, 1/n was 1.0722, and k was 0.0041. After adsorption, the fractional composition of Pb was changed. The exchangeable, carbonate, reducible fractions were increased, and the organic fraction was not changed, and the residual fraction was decreased.

• KSBB Journal
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• v.13 no.3
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• pp.295-302
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• 1998

Human Erythropoietin (EPO) gene is cloned in quail fibrosarcoma cell, QT35. Because molecular weight of EPO is similar to that of serum albumin, cell culture with serum containing medium makes purification of EPO very difficult. Using fractional factorial study, we have developed serum free medium for the recombinant QT35 cell lines, QT N4D4 and QT SY-IMP, which have cloned EPO with glutamine synthetase (GS) gene amplification system and with puromycin selective marker, respectively. Among the seven frequently used medium components, fibronectin, BSA, and EGF were the most important for EPO production. However, sufficient fibronectin supplement to the medium did not make any good attachment of QT35 to culture plate over 3 days. Therefore, to maximize EPO production, we attempted a medium-shift at confluence from serum containing medium to serum free medium(QT SFM6). Using the medium-shift protocol with QT SFM6, nearly the same productivity of EPO was achieved comparing with that without medium-shift. This result was true in both QT35 cell lines in three types of culture, i.e. T flask, microcarrier and roller bottle cultures.

• Journal of Veterinary Clinics
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• v.34 no.4
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• pp.299-303
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• 2017

An 11-year-old neutered male Maltese presented for radiation therapy for nasal transitional cell carcinoma. Stereotactic body radiation therapy (SBRT) was provided for the owner's request. Clinical signs improved 6 days after radiation therapy. Adverse effects including alopecia and pigmentation on the facial region were observed at 21 days after radiation therapy. The first follow-up computed tomography (CT) 96 days after SBRT revealed that the nasal tumor had decreased by 60.63% compared with the pre-treatment volume. Clinical signs related with the tumor reassigned 151 days after SBRT, and the second follow-up CT revealed tumor relapse. The patient was died 238 days after SBRT due to tumor relapse. SBRT showed a good tumor control effect with relatively mild radiation toxicity relative to other radiation therapy modalities, in accordance with a previous study. Further studies are needed to establish an effective treatment protocol, such as total dose, fractional dose, and inter-fractional period, in canine malignant nasal tumors.

• Nuclear Engineering and Technology
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• v.47 no.7
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• pp.924-933
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• 2015

The correlation of the isotopic composition of uranium, plutonium, neodymium, and cesium with the burnup for high burnup pressurized water reactor fuels irradiated in nuclear power reactors has been experimentally investigated. The total burnup was determined by Nd-148 and the fractional $^{235}U$ burnup was determined by U and Pu mass spectrometric methods. The isotopic compositions of U, Pu, Nd, and Cs after their separation from the irradiated fuel samples were measured using thermal ionization mass spectrometry. The contents of these elements in the irradiated fuel were determined through an isotope dilution mass spectrometric method using $^{233}U$, $^{242}Pu$, $^{150}Nd$, and $^{133}Cs$ as spikes. The activity ratios of Cs isotopes in the fuel samples were determined using gamma-ray spectrometry. The content of each element and its isotopic compositions in the irradiated fuel were expressed by their correlation with the total and fractional burnup, burnup parameters, and the isotopic compositions of different elements. The results obtained from the experimental methods were compared with those calculated using the ORIGEN-S code.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.117-128
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• 1999

The removal of nitrogen oxides(NOx) from $N_{2}/O_{2}$ gas using a pulsed corona discharge was investigated as a function of the reduced electric field(E/N) and the energy density(J/L). A kinetic model was developed to characterize the chemical reactions taking place in a pulsed corona discharge reactor. The model calculates the fractional concentrations of radical species at each pulse-on period and utilizes the radicals to remove NOx for the subsequent pulse-off period. Electron collision reaction data are calculated using ELENDIF program to solve Boltzmann equation for electron energy distribution function, and the subsequent chemical reactions are calculated using CHEMKIN-II program to solve stiff ODE(ordinary differential equation) problems for species concentrations. The corona discharge energy per pulse and the time-space averaged E/N were obtained by fitting the model to experimental data. The model calculation shows good agreement with the experimental data, and predicts the formation of other species such as $NO_{2}$, $O_{3}$ and $N_{2}O$.

• Analytical Science and Technology
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• v.6 no.1
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• pp.21-27
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• 1993

Technical grade n-hexane whose purity is 54% has been purified for HPLC use. Methylcyclopentane, 2-methylpentane, and 3-methylpentane which are hardly isolated by fractional distillation were separated by the liquid-solid chromatography using molecular sieve 5A. UV and fluorescence impurities whose contents are critically regulated for HPLC solvent were removed by the adsorptive separation with alumina and silica gel. The present method also reduced the impurities of color(APHA), acidity, water, residue after evaporation, sulfur, and thiophene content, and the impurity contents were well within the specifications of HPLC solvent.