• Progress in Medical Physics
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• v.10 no.3
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• pp.151-157
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• 1999

The GafChromic film was used for the dosimetry of a balloon angio catheter filled with the radioisotope HO-166 for endovascular irradiation. The balloon angio catheter was 2 cm long and 3 mm in diameter when inflated. The isotope, Ho-166, was produced by the neutron bombardment using the research reactor in Korea Atomic Energy Research Insititute. Co-60 teletherapy beam was used for making H-D curve for the Gaf-Chromic film. The film dosimetry was measured with a videodensitometer. The radial dose distribution indicated that the absorbed dose dropped to about 20% of the surface dose at the 1 mm away from the balloon surface and at 5 mm position the dose decreased to below 1% of the surface dose. The result also shows that with the specific activity of Ho-l66, 250 mCi/ml it takes 230 seconds to deliver 1200 cGy to the region where is 1mm away from the balloon surface. The concentric isodose curves were also presented. The Ho-166 is an another alternative for endovascualr irradiation to prevent restenosis after PTCA (Percutaneous Trans Coronary Angioplasty)

• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.705-714
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• 1995

A new analytical luminescence method for the Eu+3 and Tb+3 ions was studied using the luminescence enhancement by the treatment of the o-phenanthroline on the nylon membrane. Compared to the specific emission intensities of the ions in aqueous(or ethanol) solution, if the aqueous ion is spotted on the nylon membrane, the luminescence intensities were extremely enhanced. There was additional enhancement effect of the luminescence intensities of the ions on the nylon membrane, if the ion on the nylon membrane is treated with o-phenanthroline. Based on the luminescence enhancement, the detection limits were lowered by more than 7 order of magnitude compared to that of solution sample, and also lowered by about 1 order of magnitude compared to that of previous TLC method. The dynamic ranges and correlation coefficients of the calibration curves near the detection limit were 2∼3 order and ∼0.99, respectively. It was also shown that the luminescence intensity was in its maximum when the ion on the nylon is treated with ∼4 mole ratio of o-phenanthroline. The energy-transfer mechanism was explained for the theoretical background of the luminescence enhancement.

• Journal of the Korean Geotechnical Society
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• v.34 no.12
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• pp.105-113
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• 2018

In this study, the engineering properties including bearing capacity of subgrades stabilized with a binder are analyzed by laboratory and field experiments. The main components of the binder are CaO and $SO_3$. After the binder was mixed with a low plasticity clay, the passing rates were relatively decreased as the sieve mesh size increased. Not only did the soil type change to silty sand, but engineering properties, such as the plasticity index and modified California bearing ratio (CBR), were improved for the subgrade. A comparison of the compaction curves of the stabilized subgrade and field soil compacted with the same energy demonstrated an increase of approximately 6% in the maximum dry unit weight, slight decrease in optimum moisture content, and considerable increase improvement in grain size. In the modified CBR test, the effect of unit weight and strength increase of the modified soil (with a specific amount of binder) was remarkably improved. As the proportion of granulated material increased after the addition of binder, the swelling was reduced by 3.3 times or more during initial compaction and 6.5 times by final compaction. The unconfined compressive strength of the specimens was maintained at the homogeneous value with a constant design strength. The stabilized subgrade was validated by applying it in the field under the same conditions; this test demonstrated that the bearing capacity coefficients at all six sites after one day of compaction exceeded the target value and exhibited good variability.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.2
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• pp.93-101
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• 2007

In order for bioremediate the benthic layer in polluted inner Bay, the effects of irradiance and wave-length irradiated from light emission diode (LED) on the growth of benthic diatom Nitzschia sp. (Hakozaki Bay strain of Japan) were investigated. The Nitzschia sp. was cultured under blue LED (450 nm), yellow LED (590 nm), red LED (650 nm) and fluorescent lamp (mixed wavelengths). At $25^{\circ}C$ and 30 psu, the growth of Nitzschia sp. showed its peak at $20\;{\mu}mol\;m^{-2}\;s^{-1}$ (blue LED) and $40\;{\mu}mol\;m^{-2}\;s^{-1}$ (fluorescent lamp), and was inhibited at the irradiance higher than that irradiance. Nitzschia sp. in yellow LED and red LED is fitted by a rectangular hyperbolic curve because no photoinhibition was observed under maximum irradiance used in this study. The irradiance-growth curves were described as ${\mu}=-0.46{\exp}(1-I/6.32)+0.46-0.00043I,\;(r^2=0.98)$ under blue LED, ${\mu}=0.42(I+7.87)/(I+58.9),\;(r^2=0.99)$ under yellow LED, ${\mu}=0.39(I+3.39)/(I+21.6),\;(r^2=0.94)$ under red LED, ${\mu}=-0.38{\exp}(1-I/7.23)+0.38-0.00016I,\;(r^2=0.96)$ under fluorescent lamp. Maximum specific growth rate of blue LED, yellow LED, red LED and fluorescent lamp was $0.44\;day^{-1},\;0.42\;day^{-1},\;0.39\;day^{-1}$ and $0.37\;day^{-1}$, respectively. The absorption coefficient ($a_{ph}$) of Nitzschia sp. was similar under all the wavelengths (400 nm-700 nm), although maximum $a_{ph}$ was $0.0224\;m^2\;mg\;chi.\;{\alpha}^{-1}$ in 472 nm and $0.0179\;m^2\;mg\;chi.\;{\alpha}^{-1}$) in 663 nm. The results may indicate the possibility of environmental improvement around the benthic layer in polluted coastal area because microphytobenthos growth is stimulated by means of irradiated blue LED at the benthic boundary layer during both autumn and winter, and yellow LED, which might have been suppressed growth of harmful algae, at the layer during both spring and summer.