• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.247-256
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• 2024

The glass series modified by tungsten oxide was created using the compounds (75-x) B₂O₃- 10SrCO₃- 8TeO₂- 7ZnO - xWO₃, where x = 0, 1, 5, 10, 22, 27, 34, and 40% mole percentage. A UV-visible spectrophotometer and thermogravimetric-differential thermal analysis (TG-DTA) methods were employed to characterize the specimen's optical and phase transition attributes, respectively. The mass-attenuation coefficient (AC) of all created glasses from BSTZW0 to BSTZ7 was estimated using Geant4 code from 0.05 to 3 MeV and compared to the XCOM software results, with a relative difference of less than 2% between the two results. The increase of WO₃ percentage lead to an increase in the Linear-AC at each studied energy, and this is mainly due to the fact that the higher the percentage of WO₃ in the glass increases its density which causes an increase in the Linear-AC, so an energy of 0.06 MeV, as an example, the values of the Linear-AC was 4.009, 4.509, 5.442, 6812, 8.564, 9.856, 10.999 and 11.628 cm^-1 form BSTZW0 too BSTZW7, respectively. The Half-VL (value layer), Mean-FP (free path), Tenth-VL, and Radiation attenuation performance (RAP) were also calculated for the current BSTZW-glass samples and revealed that BSTZW7 had the best gamma ray attenuation performance at all discussed energies when compared to other studied glass samples.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.1035-1040
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• 2003

High $T_{c}$ superconducting B $i_2$S $r_2$CaC $u_2$ $O_{8+d}$ (BSCCO2212) films were prepared by a metallorganic decomposition (MOD) method. The metal organic solution of BSCCO2212 was spin-coated on MgO (100) substrates at 3000 rpm for 1 min. To achieve a high critical current density, we controlled heat-treatment conditions and atmosphere. The films were annealed at temperature 75$0^{\circ}C$ ∼ 80$0^{\circ}C$ in $O_2$ or air. We obtained c-axis orientated BSCCO thin films on MgO substrates. The annealed sample at 77$0^{\circ}C$ with $O_2$ showed the critical temperature about 77 K and critical current denstity of 1.19 ${\times}$ 10$^{5}$ A/$\textrm{cm}^2$ about 13 K.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.132-135
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• 1999

Recently, the ceramics of high permittivity are applied to DRAM and FRAM. In this study, (B $a_{x}$ S $r_{l-x}$)Ti $O_3$(BST) ceramics thin films were prepared by Sol-Gel method. BST solution was made and spin-coated on Pt/ $SiO_2$/Si substrate at 4000 [rpm] for 10 seconds. Coated specimens were dried at 150[$^{\circ}C$] for 5 minutes. Coating process was repeated 3 times and then sintered at 750[$^{\circ}C$] for 30 minutes. Each specimen was analyzed structure and electrical characteristics. Thickness of BST ceramics thin films are about 2000($\AA$). Dielectric constant and loss of thin films was little decreased at 1[KHz] ~1[KHz]. Dielectric constant and loss to frequency were 250 and 0.02 in $Ba_{0.7}$S $r_{0.3}$Ti $O_3$. The properly of leakage current as the realation between the current and the voltage was that change of the leakage current was stable when the applied voltage was 0~3[V].

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.85-85
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• 1999

Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT)는 높은 유전율로 인해 강유전체 메모리 소자의 응용을 위한 연구가 되고 있으며 또한 전왜(electrostrictive)성을 갖고 있어 이력현상을 갖지 않음으로 최근 들어 미세전기기계소자(MEMS)로의 연구가 활발히 되고 있다. 본 연구에서는 MEMS 소자로서의 응용을 위해 저응력 SiNx가 형성된 Si 기판위에 Pt 전극 혹은 산화물 전극 SrRuO3를 갖는 PMN-PT 박막 캐패시터를 제조하였다. 박막 하부의 구조는 금속전극의 경우 Pt/Ti/LTO/SiNx/Si이고 산화물전극은 SrRuO3/Ru/SiNx/Si의 구조를 갖는다. PMN-PT 박막은 alkoxide를 기반으로 회전 coating 방법을 사용하여 박막 하부층의 변화를 주어서 성장시켰다. PMN-PT 용액의 합성은 분말합성법에서 사용하는 columbite 방법을 응용하여 상대적으로 반응정도가 낮은 Mg를 Nb와 우선 반응하여 Mg-Nb solution을 얻고 Pb-acetate 용액과 합성하여 PMN을 제조한 후 PT를 반응시켜서 제조하였다. PMN-PT 박막에서 동일한 공정조건 하에서 박막 하부층의 구조에 따라서 PMN-PT 박막의 조성이 A2B2O6의 조성을 가지는 파이로클러어상이 형성되거나 또는 ABO3인 페로브스카이트상이 형성되는 것을 관찰하였다. 금속 전극인 Pt를 하부전극으로 사용한 경우는 혼재상이 형성되어 패로브스카이드 PMN-PT를 얻기 위해 seed layer로서 PbTiO3를 사용하였으며 이러한 seed layer 위에 형성된 PMN-PT를 형성하는 경우 rutile 구조인 RuO2 위에 성장시킨 PMN-PT는 파이로클로어와 페로브스카이트의 혼재상이 얻어졌으나 pseudo-perovskite 구조인 SrRuO3 박막 위에 형성된 PMN-PT 박막에서는 페로브스카이트가 주된 상으로 얻어졌다. 즉 하부층(전극 또는 seed layer)으로 perovskite 구조를 갖는 박막을 형성하게 되면 페로브스카이트를 갖는 PMN-PT 박막을 얻을 수 있었다. 전기적인 특성은 상부전극으로 Pt를 사용하여 HP 4194A로 측정을 하였다. PT seed layer를 포함한 PMN-PT 박막은 유전상수 1086과 유전손실 2.75%을 가졌다.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3212-3216
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• 2010

A new rhodamine-based sensor 1 was designed and synthesized by incorporating rhodamine B and benzimidazole moieties. Sensor 1 exhibits high selectivity and sensitivity to $Cu^{2+}$ in $CH_3CN$-water solution (HEPES buffer, pH = 7.0) with an obvious color change from colorless to pink. Other metal ions such as $Hg^{2+}$, $Ag^+$, $Pb^{2+}$, $Sr^{2+}$, $Ba^{2+}$, $Cd^{2+}$, $Ni^{2+}$, $Co^{2+}$, $Fe^{2+}$, $Mn^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Ce^{3+}$, $Mg^{2+}$, $K^+$ and $Na^+$ had no such color change and have no significant influence on $Cu^{2+}$ recognition process. The interaction of $Cu^{2+}$ and sensor 1 was proven to adopt a 1:1 binding stoichiometry and the recognition process is reversible.

• Progress in Superconductivity
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• v.4 no.2
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• pp.109-113
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• 2003

We have developed a planar-type single layer second-order $high-T_{c}$ SQUID gradiometer, which can detect the $d^2$$B_{z/}$dxdy of the second-order field gradient. This SQUID gradiometer consists of four-way 'clover-leaf' pick-up loops and is coupled directly to a 4-junction dc SQUID in such a way that the coupling polarity of the two diagonal loops is opposite to that of the other two loops. The pickup loops are intrinsically balanced for both uniform field and the 1 st-order field gradient. The $YBa_2$$Cu_3$$O_{7}$ thin film was made by pulsed laser deposition method on $SrTiO_3$ single crystal substrate and patterned by photolithography with Ar ion milling technique. Response of this gradiometer was tested for both uniform field and the 2nd-order field gradient. Details of the design, fabrication, and results will be discussed.

• Bulletin of the Korean Chemical Society
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• v.17 no.9
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• pp.794-798
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• 1996

Solid solutions of the nonstoichiometric Dy1-xSrxCoO3-y system with the compositions of x=0.00, 0.25, 0.50, 0.75, and 1.00 have been synthesized by the solid state reaction at 1000 ℃ under atmospheric air pressure. The crystallographic structures of the solid solutions are analyzed by the powder X-ray diffraction patterns at room temperature. The analyses assign the compositions of x=0.00 and 0.25 to the orthorhombic system with space group of Pbnm/D2h16, the compositions of x=0.50 and 0.75 to the tetragonal system like a typical SrCoO2.86, and the composition of x=l.00 or SrCoO2.50 to the brownmillerite type system with space group of I**a. The reduced lattice volumes increase with x value due to the larger radius of Sr2+ ion than that of Dy3+ ion. The mole ratio of Co4+ ion to total Co ion with mixed valence state between Co3+ and Co4+ ions at B sites or τ value has been determined by an iodometric titration. All the samples except for the DyCoO3 compound show the mixed valnce state and thus the composition of x=0.50 has the maximum τ value in the system. The oxygen vacancies increasing with x value are randomly distributed over the crystal lattice except for the composition of x=l.00 which have the ordering of the oxygen vacancies. The nonstoichiometric chemical formulas of the Dy1-xSrxCo3+1-τCo4+τO3-(x-τ)/2 system are formulated from the x, τ, and y values. The electrical conductivity in the temperature range of 100 to 900 K increases with τ value linearly because of positive holes of the Co4+ ions in π* band as a conducting carrier. The activation energy of the x=0.50 as Ea=0.17 eV is minimum among other compouds. Broad and high order transition due to the overlap between σ* and π* bands broadened by the thermal activation is observed near 1000 K and shows a low temperature-semiconducting behavior. Magnetic properties following the Currie-Weiss law show the low to high spin transition in the cobaltate perovskite. Especially, the composition of x=0.75 presents weak ferromagnetic behavior due to the Co3+-O2--Co4+ indirect superexchange interaction.

• Archives of Pharmacal Research
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• v.25 no.2
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• pp.191-196
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• 2002

The water extract from the root bark of Cortex Mori (CM, Morus alba L.: Sangbaikpi), a mulberry tree, has been known in Chinese traditional medicine to have antiphlogistic, diuretic, and expectorant properties. In this study, the cytotoxicity of CM against tumor cells and its mechanism was examined . CM exhibited cytotoxic activity on K-562, B38O human leukemia cells and B16 mouse melanoma cells at concentrations of > 1 mg/ml. A DNA fragmentation, PARP cleavage, and nuclear condensation assay showed that those cells exposed to CM underwent apoptosis. The water extract of Scutellarie Radix (SR) was used as a negative control and showed no cytotoxicity in those cells. The flow cytometric profiles of the CM-treated cells were also indicative of apoptosis. However, they did not appear to exert the G1 arrest, which is observed in other tubulin inhibitor agents such as vincristine, taxol. The protein-binding test using Biacore and a microtubule assembly-disassembly assay provided evidence showing that CM bound to the tubulins resulting in 3 markets inhibition of the assembly, but not the disassembly of microtubules. The possible nonspecific effect of the CM extract could be excluded due to the results using SR, which did not affect the assembly process. Overall, the water extract of CM induces apoptosis of tumor cells by inhibiting microtubule assembly.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.108-111
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• 2015

Purpose Lately, in accordance with the increasing interest about Healthcare accreditation program and International laboratory accreditation scheme, requirements about the instrument quality management are gradually taking shape. In nuclear medicine In vitro laboratory, the most typical instruments are multi detector gamma counter and automatic dispensing system. Each laboratory continue with the quality control adequate for circumstances. The purpose of this study is to application and establish the new Calibrator[I-125]Set which is efficient at standardization of equipment quality management. Materials and Methods Deviation between detectors were measured with 12 solid samples of the Calibrator[I-125]Set. their activities differ from each other by less than 1%. Multi detector gamma counters are GAMMA-10;Shinjin medics. Inc, Goyansi, Korea(Gamma counter A), SR300;Stratec biomedical systems AG, Gewerbestr, Germany(Gamma counter B) and COBRA II; Packard Instrument Co. Inc, Meriden, USA(Gamma counter C). Evaluation of two automatic dispensing system used A, B liquid tracer of the Calibrator[I-125]Set. After dispensing and counting, calculated using the ratio of the measured value and proposed value. We used solution A for 20, 25ul and solution B for 50, 100ul. Method of data analysis and reference range was provided by kit documentation. Furthermore, we could calculate our counter efficiency indirectly. Results The CV(%) of measured values by Gamma counter A, B, C are 0.34, 0.70, 1.30. Calculated value are 1.05314, 2.10419, 4.08485. Provided reference range is less than 3. A dispensing system's calculated values are 0.986, 0.989, 1.023, 1.017 and B are 0.874, 0.725, 1.021, 0.904. Provided reference range is from 0.95 to 1.05. Also, counter's efficiency are 74.18, 72.79, 74.32% at counter A, B, C and efficiency of the one detector counter is 79.26%. Conclusion If using this Calibrator[I-125]Set after verifying whether quality assurance, is applicable to equipment quality management on behalf of the role of gold standard.

• The Journal of the Petrological Society of Korea
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• v.27 no.1
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• pp.37-47
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• 2018

Volcanic ash samples of historical eruptions from Mt. Baekdu were analyzed for major oxides, trace and rare earth elements by a variety of analytical techniques. The results indicate that the ashes consist of approximately 58.8~71.1 wt.% $SiO_2$, 9.6~16.8 wt.% $Al_2O_3$, 4.5~6.9 wt.% $Fe_2O_{3t}$, 0.1~1.7 wt.% MgO, 0.3~1.6 wt.% CaO, 5.2~6.3 wt.% $Na_2O$, 4.3~5.9 wt.% $K_2O$ and less than 1.2 wt.% $TiO_2$. Thirty two trace metals including Ba, Cu, Cr. Co, Ni, Sr, V, Zn, and Zr were analyzed. The ashes can be divided two groups: group A(1 ka Millennium pumice, 1668 and $190{\underline{3}}$ pumice) and group B(1702 pumice) according to the relative enrichment of HREEs. The abundances of heavy metals such as Cu, Co, Mn, and Zn were relatively low. As compared to the Sakurajima volcanic ash, Baekdusan volcanic ash has low concentrations of Y, Nb, Pb, U, Sc, V, Ni and Cu and high concentrations of Zr, Ba, Hf, Cr, Co, Zn and rare-earth (except Eu).