• Proceedings of the Korean Nuclear Society Conference
• /
• 2005.10a
• /
• pp.879-880
• /
• 2005

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.27 no.4
• /
• pp.328-331
• /
• 1991

LiF(Mg,Cu,Na,Si) 형광체의 ${\gamma}$선과 $\beta$선에 대한 TSEE 특성을 조사하였다. 상(60)Co ${\gamma}$선에 대한 감도는 약 450 counts/mR이었고, 여러 가지 $\beta$선에 대한 TSEE 에너지 의존성은 $\beta$입자의 평균에너지 0.02MeV에서 0.8MeV 사이에서 $\pm$10%이었다. 그리고 제작된 형광체 앞면에 7mg.cm 상(-2)의 인체 등가물질을 두 면 입사 $\beta$입자의 에너지에 무관하게 피부 흡수 선량을 측정할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.122-122
• /
• 2010

ZnO is a widely investigated material for the blue and ultraviolet solid-state emitters and detectors. It has been promoted due to a wide-band gap semiconductor which has large exciton binding energy of 60 meV, chemical stability and low radiation damage. However, there are many problems to be solved for the growth of p-type ZnO for practical device applications. Many researchers have made an efforts to achieve p-type conductivity using group-V element of N, P, As, and Sb. In this letter, we have studied the optical characteristics of the antimony-doped ZnO (ZnO:Sb) thin films by means of photoluminescence (PL), PL excitation, temperature-dependent PL, and time-resolved PL techniques. We observed donor-to-acceptor-pair transition at about 3.24 eV with its phonon replicas with a periodic spacing of about 72 meV in the PL spectra of antimony-doped ZnO (ZnO:Sb) thin films at 12 K. We also investigate thermal activation energy and carrier recombination lifetime for the samples. Our result reflects that the antimony doping can generate shallow acceptor states, leading to a good p-type conductivity in ZnO.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.12
• /
• pp.1781-1784
• /
• 2003

Determination of Co(II) ion as a 4-(2-thiazolylazo)resorcinol(TAR) or 5-methyl-4-(2-thiazolylazo)resorcinol(5MTAR) chelate was accomplished by reversed-phase capillary high-performance liquid chromatography (RP-Capillary-HPLC) using a Vydac $C_4$ column and MeCN-water mixture as mobile phase. The effect of change in pH and MeCN percentage of the mobile phase on the retention factor, k and peak intensity were evaluated. It was found that 30% MeCN (v/v) of pH 5.60 or 7.20 was adequate as mobile phase when TAR or 5MTAR is used. Detection limit (D.L., S/N=3) in each case was $2.0\;{\times}\;10^{-7}$M (11.8 ppb) and $3.0\;{\times}\;10^{-7}$ M (17.7 ppb). The Co(II) ion in mineral and waste water was determined with the optimum column and mobile phase.

• YAKHAK HOEJI
• /
• v.49 no.5
• /
• pp.416-421
• /
• 2005

Cudrania tricuspidata Bereau (Moraceae) have been used for anti-inflammatory, anti-hepatotoxic, anti-hyper­tensive and anti-diabetic activities. In order to investigate the efficacy of antioxidant activity, the bio-activity guided fraction and isolation of Biologically active substance were performed. $H_{2}O,\;30\%,\;60\%,\;100%$ MeOH and acetone fractions were examined on the antioxidant activity by DPPH method. It was shown that $30\%,\;60\%,\;100\%$ MeOH fractions have sig­nificantly antioxidant activity. From $30\%$ MeOH fraction, two dihydroflavonoid glycosides dihydroquercetin 7-O-$\beta$-D-glu­copyranoside (I), dihydrokaempferol 7-O-$\beta$-D-glucopyranoside (V) were isolated and $60\%$ MeOH fraction, six flavonoids including quercetin 3-O-$\alpha$-L-rhamnopyranosyl($1\rightarrow6$)-$\beta$-D-glucopyranoside (II), quercetin 3-O-$\beta$-D-glucopyranoside (III), quercetin 7-O-$\beta$-D-glucopyranoside (IV), kaempferol 3-O-$\alpha$-L-rhamnopyranosyl($1\rightarrow6$)-$\beta$-D-glucopyranoside (VI), kaempferol 3-O-$\beta$-D-glucopyranoside (VII), kaempferol 7-O-$\beta$-D-glucopyranoside (VIII) were isolated. To investigate the antioxidant activities of each compounds, we measured radical scavening activity with DPPH method and anti-lipid per­oxidative efficacy on low density lipoprotein (LDL) with TBARS assay. Four compounds of quercetin glycosides (I, II, III, IV) showed significant antioxidant activity.

• Journal of the Korean Chemical Society
• /
• v.37 no.6
• /
• pp.612-617
• /
• 1993

Some vanadium(III) complexes have been prepared from the reaction of VC$l_3$ with N, P, O-donating ligands and characterized by elemental analysis, $^1$H-NMR infrared and UV-Visible spectroscopy. 3,5-Lutidine, 1,2-phenylenediamine, 8-hydroxyquinoline, 9,10-phenanthrenequinone, triphenylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane and 1,1'-bis(diphenylphosphino)ferrocene were chosen as coordinating ligands. Stretching frequency ${\nu}g$(V-Cl) of complexes appears) at 298∼367 cm-1, which show octahedral geometries. Stretching frequency of ${\nu}g$(V-X) (X = N, P, O) indicates that ligands are coordinated to vanadium(III). Stretching frequency ${\nu}g(C{\equiv}N)$ of acetonitrile in these complexes are characteristically shifted to about 70 c$m^{-1}$ higher compared with that of a free ligand (2260 c$m^{-1}$). Bending frequency of $\delta(C{\equiv}N)$ is also shifted to about 60 c$m^{-1}$ higher compared with that of a free ligand (377 c$m^{-1}$). Finally each vanadium(III) complex showed the following formulation; [VC$l_3$(L)$_2$MeCN] or [VC$l_3$(L-L)MeCN].

• Journal of Radiation Protection and Research
• /
• v.22 no.2
• /
• pp.127-133
• /
• 1997

In this study an EGS4 simulation code was used to calculate real energy spectrum from measured ${\gamma}$-ray energy spectrum obtained using 2-dimensional radiation monitoring system. As a result, the $39{\times}39$ response matrix was calculated the energy range of 0.1 to 2 MeV which energy interval of 50 keV The real energy spectrum for Co-60 radioisotope was calculated using inverse of response matrix. It was confirmed that the calculated response matrix was useful to the analysis of the measured energy spectrum for the radiation monitoring system.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.1
• /
• pp.23-29
• /
• 2016

Zinc oxide of hexagonal wurzite, is known as n-type semiconductor. It has a wide band gap energy of 3.37 eV and large exciton binding energy of 60 meV. It can be widely applied to gas sensors, laser diodes, dye-sensitized solar cells and degradation of dye waste. The use of microwave hydrothermal synthesis brings a rapid reaction rate, high yield, and energy saving. Amine additives control the different particle shapes because of the chelate effect and formation of hydroxide ion. In this study, zinc nitrate hexahydrate was used as zinc precursor. In addition, ethanolamine, ethylenediamine, diethylenetriamine, and hexamethylenetetramine are used as shape control agent. The pH value was controlled as 11 by NaOH. The shapes of zinc oxide are star-like, rod, flower-like, and circular cone. In order to analyze physical, chemical, and optical properties of ZnO with diverse amine additives, we used XRD, SEM, EDS, FT-IR, UV-Vis spectroscopy, and PL spectroscopy.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.2
• /
• pp.1555-1562
• /
• 2015

Metal oxide semiconductors have been applied in several areas, such as solar cells, sensor, optical elements and displays, due to the high surface area, unique electrical and optical characteristics. Zinc oxide among the metal oxide has excellent physicochemical properties. Zinc oxide is a n-type semiconductor with a wide direct transition band gap of 3.37 eV at room temperature and large exciton binding energy of 60 meV. Cation-doped zinc oxide studies were conducted to complement the electrical and optical characteristics. In this paper, Al-doped ZnO was synthesized by hydrothermal synthesis using microwaves. ZnO was synthesized by adjusting the precursor ratio and using different dopants. The optimal ZnO synthesis conditions for crystal shape and optical properties were determined. The optical properties of aluminum doped zinc oxide were then examined by SEM, XRD, PL, UV-vis absorbance spectrum, and EDS.

• Progress in Medical Physics
• /
• v.13 no.4
• /
• pp.195-201
• /
• 2002

Several investigators have presented the effects of external magnetic fields on the dose distributions for clinical electron and photon beams. We focus the low energy electron beam with more lateral scatter In this study we calculated the beam profiles for an clinical electron beam of 6 MeV with longitudinal magnetic fields of 0.5 T-3.0 T using a Monte Carlo code. The principle of dose enhancements in the penumbra region is to deflect the laterally scattered electrons from its initial direction by the skewness of the laterally scattered electrons along the direction of magnetic field lines due to Lorentz force under longitudinal magnetic field. To discuss the dose enhancement effect on the penumbra area from the calculated results, we introduced the simple term of penumbra reduction ratio (PRR), which is defined as the percentage difference between the penumbra with and without magnetic field at the same depth. We found that the average PRR are 33%, and 49% over the depths of 1.5 cm, 2.0 cm, and 2.4 cm for the magnetic fields of 2.0 T and 3.0 T respectively. For the case of 0.5 T and 1.0 T the effects of magnetic filed were not observed significantly. In order to obtain the dose enhancement effects by the external magnetic field, we think that its strength should be more than 2 T approximately. We expect that the PRR would be saturated to 50-60% with magnetic fields of 3 T-5 T As a result of these calculations we found that the penumbra widths can be reduced with increased magnetic fields. This Penumbra reduction is explained as a result of electron lateral spread outside the geometrical edges of the beam in a longitudinal magnetic field. This means that the electron therapy benefits from the external magnetic fields.