• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.208-211
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• 2002

$Bi_2Sr_2CuO_x$(Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.281-283
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• 2001

$Bi_{2}Sr_{2}CuO_{x}$(Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion bearn sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition. two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit. then three dimensional growth takes place. Since Cu element is the most difficult to oxidize. only Sr and Bi react with each other predominantly. and forms a buffer layer on the substrate in an amorphous-like structure. which is changed to $SrBi_{2}O_{4}$ by in-situ anneal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.329-330
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• 2005

Bi-Sr-Ca-Cu-O thin films have been fabricated by sputter deposition method. During the deposition, 10 and 90 wt%-ozone/oxygen mixture gas of typical pressure of $1\sim9\times10^{-5}$ Torr are supplied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal out that a buffer layer with some different compositions is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.

• Journal of the Semiconductor & Display Technology
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• v.5 no.4 s.17
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• pp.5-9
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• 2006

The SCT thin films are deposited on Pt-coated electrode($Pt/TiN/SiO_2/Si$) using RF sputtering method with Sr/Ca ratio. The maximum grain of thin films is obtained by ratio of Ca at 15 mol%. The dielectric constant was increased with increasing the ratio of Ca, while it was decreased if the ratio of Ca exceeded over 15 mol%. The dielectric constant changes almost linearly in temperature ranges of $-80{\sim}+90$. All SCT thin films used in this study show the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency is observed above 200 kHz. The current-voltage characteristics of SCT thin films showed the increasing leakage current as the measuring temperature increases.

• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.90-95
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• 2000

The ferrites, CuFe2O4 and SrFe12O129, were applied to decompose H2O for H2 generation. The ferrites prepared by the coprecipitation were reduced by CH4 gas to make the oxygen deficient ferrite. H2O was decomposed to form H2 by the oxygen deficient iron oxide, and the decomposition reactions were accelerated by the addition of divalent metals such as Cu and Sr in the ferrites. The spinel type CuFe2O4 containing a relatively large amount of divalent metals was more effective to H2 generation than magnetoplumbite type SrFe12O19 in H2O decomposition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.281-283
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• 2001

Bi$_2$Sr$_2$CuO$\_$x/(Bi-2201) thin films were fabricated layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to SrBi$_2$O$_4$ by in-situ anneal.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1337-1338
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• 2006

BiSrCaCuO was prepared by the thermal pyrolysis method. The solid precursor produced by the dehydration of the gel at $120^{\circ}C$ for 12h is not in the amorphous state as expected but in a crystalline state. X-ray diffraction peaks of nearly the same angular position as the peaks of high Tc phase were observed in the precursor. After pyrolysis at $90^{\circ}C$ and calcination at $840^{\circ}C-920^{\circ}C$ for 4h, the high Tc phase was cleary observed. In this paper, the establishment of fabrication condition and additive effects of second elements were examined so as to improve the related properties to the practical use of BiSrCaCuO superconductor, and we reported the production of the BiSrCaCuO high Tc superconductor by the pyrolysis method.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.119-121
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• 2002

$Bi_2Sr_2CuO_x$ thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method, 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

• Journal of Radiation Protection and Research
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• v.21 no.3
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• pp.147-153
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• 1996

The Korea Atomic Energy Research Institute(KAERI) conducted a intercomparison study for personnel dosimetry services in Korea to enhance the accuracy and precision of the dosimetry system. Nine types of dosimeters(6 TLD, 3 film badge) from 7 institutions took part in this intercomparison study. Each participant submitted 30 dosimeters including transit control for irradiations. Both TLDs and film badges were irradiated with Cs-137 gamma, Sr/Y-90 beta and 4 X-ray beams in ISO wide series. Four dosimeters were irradiated on phantom with same dose equivalent for each field category. The delivered dose equivalent was in the range of $0.1{\sim}10mSv$. The participants assessed the results of their dosimeter readings in terms of the ICRU operational quantities for personal monitoring, Hp(10) and Hp(0.07). Most participants except 1 dosimeter estimated the delivered dose equivalent with biases less than ${\pm}25%$ for Cs-137 and Sr/Y-90. But for X-rays, the biases exceeded ${\pm}35%$ in some cases bacause the dose evaluation algorithm was based on the ANSI N13.11 X-ray fields which are different from those given by ISO.

• Journal of Radiation Protection and Research
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• v.26 no.2
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• pp.87-91
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• 2001

The optimized derived intervention levels for animal products were evaluated based on cost-benefit analysis. From these results, the radionuclide concentrations in animal feedstuffs for use were derived. It was shown that radionuclide concentrations in animal feedstuffs for use depend strongly on animal products, radionuclides and feeding period (period from the starting time to be led with contaminated feedstuffs to production time of animal products). In case of feedstuffs contaminated with long-lived radionuclides ($^{l37}Cs,\;^{90}Sr$), the feedstuffs with lower contamination should be supplied to animals with increase of feeding period due to the bioaccumulation of radionuclides. While, in case of feedstuffs contaminated with short-lived radionuclides ($^{131}I$), the feeding of higher contaminated feedstuffs was possible with increase of feeding period due to radionuclide decay. It was shown that $^{137}Cs$ concentration in animal feedstuffs lot use was lower than $^{90}Sr$ concentration. It is primarily, due to the higher feed-animal product transfer factor of $^{137}Cs$.