• Journal of Radiation Industry
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• v.4 no.4
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• pp.347-352
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• 2010

In this study, we addressed a novel nanosized curdlan-silica complex, which is curdlan bound to silica, for the development of a sustain-releasing micro element fertilizer formulation. The complex was obtained as follow steps; First, Curdlan polymer, sodium silicate ($Na_2SiO_3$) and isopropyl alcohol were dissolved in DDW. Next the resultant solution was irradiated by $^{60}Co$ gamma-irradiator (150 TBq of capacity; ACEL, Canada). Then $MgSO_4$ was treated with the resultant solution. The obtained colloidal solution was dried by freeze dryer. Finally, we obtained a novel nanosized curdlan-silica formulation containing $MgSO_4$ from the colloidal solution. The morphology of the complex was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanosized curdlan-silica complex has a particle size ranging from 20 to 80 nm and high stability. Our results suggested that the nano-complex can be applicable to use in various sustain-releasing formulation for pesticide delivery system (PDS).

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1036-1042
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• 1998

The preconcentration and determination of trace elements in water samples were studied by a solvent sublation utilizing dithizonate complexation. After metal dithizonates were formed, trace amounts of cadmium, cobalt, copper and lead were floated and extracted into small volume of a water-immiscible organic solvent on the surface of sample solution and determined in the solvent directly by GF-AAS. Several experimental conditions as formation condition of metal-dithizonate complexes, pH of solution, amount of dithizone, stirring time, the type and amount of surfactants, N2 bubbling rate and so on were optimized for the complete formation and effective flotation of the complexes. And also four kinds of light solvents were compared each other to extract the floated complexes, effectively. After the pH was adjusted to 4.0 with 5 M HNO3, 8.0 mL of 0.05% acetone solution of dithizone was added to 1.00 L water sample. The dithizonate complexes were flotated and extracted into the upper methyl isobutylketone (MIBK) layer by the addition of 2.0 mL 0.2% ethanolic sodium lauryl sulfate solution and with the aid of small nitrogen gas bubbles. And this solvent sublation method was applied to the analysis of real water samples and good results of more than 85% recoveries were obtained in spiked samples.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.582-588
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• 1995

The preconcentration and determination of trace Cd(Ⅱ), Cu(Ⅱ), Pb(Ⅱ), Mn(Ⅱ) and Zn(Ⅱ) in water samples were studied by the precipitate flotation using La(OH)3 as a coprecipitant. The analytes were quantitatively coprecipitated by adding 3.0 mL of 0.1 M La(Ⅲ) solution in a 1,000 mL water sample and adjusting the pH to 9.5 with NaOH solution. After the addition of the 1:8 mixed surfactant solution of each 0.1% sodium oleate and sodium lauryl sulfate, the solution was stirred with a magnetic stirrer for 10 minutes. The precipitates were floated to the surface by bubbling with nitrogen gas and collected in a small sampling bottle. The precipitates were dissolved in nitric acid and then the solutions were diluted to 25.00 mL with a deionized water. The analytes were determined by flame atomic absorption spectrometry. This procedure was applied to the waste water analysis. This technique was simple, convenient and especially rapid for the analysis of a large volume of sample. And also, from the recoveries of better than 92% which were obtained from real samples, this method could be judged to be applicable to the preconcentration and quantitative determination of trace elements in water samples.

• Structural Engineering and Mechanics
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• v.48 no.6
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• pp.879-914
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• 2013

In part I of the article, formulation and characteristics of the several well-known structural geometrical nonlinear solution techniques were studied. In the present paper, the efficiencies and capabilities of residual load minimization, normal plane, updated normal plane, cylindrical arc length, work control, residual displacement minimization, generalized displacement control and modified normal flow will be evaluated. To achieve this goal, a comprehensive comparison of these solution methods will be performed. Due to limit page of the article, only the findings of 17 numerical problems, including 2-D and 3-D trusses, 2-D and 3-D frames, and shells, will be presented. Performance of the solution strategies will be considered by doing more than 12500 nonlinear analyses, and conclusions will be drawn based on the outcomes. Most of the mentioned structures have complex nonlinear behavior, including load limit and snap-back points. In this investigation, criteria like number of diverged and complete analyses, the ability of passing load limit and snap-back points, the total number of steps and analysis iterations, the analysis running time and divergence points will be examined. Numerical properties of each problem, like, maximum allowed iteration, divergence tolerance, maximum and minimum size of the load factor, load increment changes and the target point will be selected in such a way that comparison result to be highly reliable. Following this, capabilities and deficiencies of each solution technique will be surveyed in comparison with the other ones, and superior solution schemes will be introduced.

• Journal of Korea Water Resources Association
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• v.41 no.7
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• pp.669-679
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• 2008

The present study examines similarity of behavior between an overtopping wave generated by a plunging wave and a dam-break flow through hydraulic model tests. The dam-break flow has been employed to estimate the overtopping effect on the basis of the dam-break flow's behavior similar to the overtopping. In this study, the overtopping velocity was measured by a modified image technique using bubble and bubble texture images called bubble image velocitmetry. From the measurements, the vertical profiles of horizontal overtopping velocity at cross-sections along the deck were presented and discussed. Maximum velocity and depth-averaged velocity at each cross-section were compared with an analytical solution solving the dam-break flow, Ritter's solution. The initial water depth of importance for the solution was determined from the tested wave condition and the overtopping measurements. The comparison shows that the solution with the initial water depth estimated using the front velocity of the overtopping wave is in good agreements with the measurements.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1775-1780
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• 2003

A continuous flow system has been developed to determine trace Cu(II), Mn(II), Ni(II) and Zn(II) in a large volume of water samples by a solvent sublation technique. The mixed solution of 1,10-phenanthroline(phen) and thiocyanate ion was used as ligands for the formation of their ternary complexes. The continuous system was constructed in this laboratory with a peristaltic pump, a mini shaker, three mixing bottles and a flotation cell by connecting each part with a polyethylene tube. The flotation conditions such as the flow rate of sample solution and the injection rates of ligand, buffer and surfactant solutions have been investigated to obtain the best sublation efficiencies. Each solution flowed into the flotation cell through each polyethylene tube by the peristaltic pumps. The ternary complexes were floated and extracted into MIBK in a flotation cell of 2 L by bubbling a nitrogen gas. The absorbances of extracted analytes in MIBK were directly measured by graphite furnace-AAS. The concentrations of 1,10-phenanthroline and thiocyanate ion were $2.6\;{\times}\;10^{-3}$ M and $2.3\;{\times}\;10^{-2}$ M in the mixed solution, respectively. The pH of sample solution was adjusted to 5.0 with a buffer solution and 1%(m/v) sodium lauryl sulphate solution was added as a surfactant to support the effective flotation of the complexes. The $N_2$ gas was bubbled at 30 mL/min for 90 minutes for 20 L of sample. Reproducible results of less than 10% RSD and recoveries of 80-120% could be obtained in real samples.

• Journal of Radiation Protection and Research
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• v.12 no.2
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• pp.19-27
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• 1987

In order to determine the $^{56}Mn\;{\gamma}$-detection efficiency of a $MnSO_4$ bath system, it is essential to do the absolute activity measurement of $^{56}Mn$ solution. For the fabrication of $^{56}Mn$ samples, a 13.718 mg of $^{56}Mn$ metal flake with 99.99% purity was irradiated for 12 minutes at the thermal neutron field of about $10^{13}n/cm^2s$ of flux density. The neutron activated $^{56}Mn$ metal sample was dissolved in 50 ml of 0.1 N-HCl solution. The $^{56}Mn$ samples were fabricated by using the dissolved stock solution and the activity of each of them was measured by the $4{\pi}{\beta}-{\gamma}$ coincidence counting technique. The obtained result was 408.070 kBq/mg with total uncertainty of 0.366% at reference date, 0 h on October 15, 1987.

• Korean Journal of Crystallography
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• v.3 no.1
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• pp.37-43
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• 1992

KTiOP04 is a nonlinear optical crystal which is most widely used for frequency doubling of the radiation of Nd : YAG laser. In the experiment, sin ale crystals of KTiOP04 were grown by TSSG technique using 3K2W04·P2O5 flux. Low temperature gradient furnace suitable for KTP single crystal growth was used. Seed crystal was placed at the surface of the solution for the purpose of better observation of the growing crystals and the possibility of diameter control. Solution included 66.7mol% KTiOP04 for all experiments and its saturation temperature was 1020℃. The conditions of single crystal growth were as follows: cooling rate 0.2℃/h, crystal rotation rate 50rpm, c -axis seed. Using these conditions, single crystals up to 23 ×25×25mm3 have been groan from about 100cc solution. We have also observed a change in the crystal growth habit which resulted in the formation of large (201) faces and small (100) faces. And some crystals have (101) faces.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.11
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• pp.117-126
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• 2003

GA(genetic algorithm) has a powerful searching ability and is comparatively easy to use and to apply as well. By that reason, GA is in the spotlight these days as an optimization skill for mechanical systems.$^1$However, GA has a low efficiency caused by a huge amount of repetitive computation and an inefficiency that GA meanders near the optimum. It also can be shown a phenomenon such as genetic drifting which converges to a wrong solution.$^{8}$ These defects are the reasons why GA is not widdy applied to real world problems. However, the low efficiency problem and the meandering problem of GA can be overcomed by introducing parallel computation$^{7}$ and gray code$^4$, respectively. Standard GA(SGA)$^{9}$ works fine on small to medium scale problems. However, SGA done not work well for large-scale problems. Large-scale problems with more than 500-bit of sere's have never been tested and published in papers. In the result of using the SGA, the powerful searching ability of SGA doesn't have no effect on optimizing the problem that has 96 design valuables and 1536 bits of gene's length. So it converges to a solution which is not considered as a global optimum. Therefore, this study proposes ExpGA(experience GA) which is a new genetic algorithm made by applying a new probability parameter called by the experience value. Furthermore, this study finds the solution throughout the whole field searching, with applying ExpGA which is a optimization technique for the structure having genetic drifting by the standard GA and not making a optimization close to the best fitted value. In addition to them, this study also makes a research about the possibility of GA as a optimization technique of large-scale design variable problems.

• The Korean Journal of Physiology and Pharmacology
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• v.10 no.4
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• pp.193-198
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• 2006

Many gastrointestinal muscles show electrical oscillation, so-called 'slow wave', originated from interstitial cells of Cajal (ICCs). Thus, a technique to freshly isolate the cells is indispensable to explore the electrophysiological properties of the ICCs. To apply an enzyme solution on the serosal surface for cell isolation, the intestine was inverted and 0.02% trypsin solution and 0.04% collagenase solution were applied to serosal cavity. After the enzyme treatment, mucosal layer was removed and longitudinal muscle layer was gently separated from the rest of tissue. The thin layer was stretched in the recording chamber and mounted on an inverted microscope. Using ${\beta}-escine$, perforated whole cell patch clamp technique was used. Under a microscope, the tissue showed smooth muscle cells and interstitial cells around the myenteric plexus. Under voltage clamp condition, three types of membrane potential were recorded. One group of interstitial cells, which were positive to methylene blue and CD34, showed spontaneous outward current. These cells had bipolar shape and were considered as fibroblast-like cells because of their peculiar shape and arrangement. Another group, positive to c-kit and methylene blue, showed spontaneous inward current. These cells had more rounded shape and processes and were considered as ICCs. The third, positive to c-kit and had granules containing methylene blue, showed quiet membrane potentials under the voltage-clamp mode. These cells appeared to be resident macrophages. Therefore, in the freshly isolated thin tissue preparation, methylene blue could easily identify three types of cells rather than morphological properties. Using this method, we were able to study electrical properties of fibroblast and residential macrophage as well as myenteric ICCs.