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차정옥,유재일,유정식,정해선,박선희,김화수,이영선,정경태 질병관리본부 2014 Osong Public Health and Research Persptectives Vol.5 No.2
Objectives To investigate the biofilm-forming related factors against MRSA bloodstream isolates and evaluates their clinical features and treatment outcomes by biofilm production. Methods We collected 126 consecutive methicillin-resistant Staphylococcus aureus (MRSA) causing blood stream infections (BSIs) at 10 tertiary hospitals from 2007 to 2009. We investigated biofilm-forming ability using a microtiter plate assay, and molecular characteristics including multilocus sequence typing, staphylococcal cassette chromosome mec and accessory gene regulator types. We compared the clinical characteristics and outcomes of patients infected with biofilm-forming and non-biofilm-forming MRSA isolates. Results Of the 126 samples, 86 (68.3%), including 5 strong level (OD570 ≥ 1.0) and 81 weak level (0.2 ≤ OD570 < 1.0), had biofilm-forming capacity. Detection of fibronectinbinding protein in biofilm-forming strains was significantly higher than biofilm non-forming ones (p = 0.001) and three enterotoxin genes (sec-seg-sei) islands had a high frequency regardless of biofilm production. However, biofilm-forming strains were more likely to be multidrug resistant (three or more non-β-lactam antibiotics) than biofilm non-forming ones [79.2% vs. 59.2%, p = 0.015, odds ratio (OR) 2.629, 95% confidence interval (CI) 1.92–5.81]. Clinical features of patients with BSIs caused by biofilm-forming MRSA strains were more likely to be hospital onset [77.9% vs. 60.0%, p = 0.024, OR 2.434, 95% CI 1.11–5.33) and more frequently occurred in patients with use of invasive devices [85.7% vs. 61.2%, p = 0.002, OR 3.879, 95% CI 1.61–8.97]. The other clinical features were compared with the clinical outcomes of the two groups and were not significant (p > 0.05). Conclusion Biofilm-forming MRSA strains showed higher frequency of fnbB gene than biofilm non-forming ones and more incidence rates on particular genotypes. And, their patient's features were not significantly different between two groups in this study, except for several clinical factors.
차정옥,안정선,이광배,Cha, J.O.,Ahn, J.S.,Lee, K.B. 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.1
$BiFeO_3(BFO)/Pb(Zr_{0.52}Ti_{0.48})O_3$(PZT) bilayer와 multilayer의 다층구조를 만들어 전기적 특성을 측정하여 같은 두께의 BFO 단층박막과 비교해 보았다. BFO와 PZT 용액을 이용하였으며 chemical solution deposition 방법으로 Pt/Ti/$SiO_2$/Si(100) 기판위에 각 박막을 증착하였다. X-ray diffraction 분석을 통해 모든 박막이 다배향(multi-orientation) 페로브스카이트 (perovskite) 구조를 가졌음을 확인하였다. BFO/PZT Bilayer와 multilayer 박막들은 BFO 단층박막의 비해 누설전류 값이 500 kV/cm에서 약 4, 5차수 정도 감소했으며, 이로 인해 BFO/PZT 다층박막의 강유전체 특성이 크게 향상되었다. BFO/PZT multilayer 다층구조 박막의 경우 안정된 이력곡선(hysteresis loop)을 나타냈으며, 잔류 분극(remanent polarization)의 값은 $44.3{\mu}C/cm^2$이었으며, 항전계($2E_c$) 값은 681.4 kV/cm였다. $BiFeO_3/Pb(Zr_{0.52}Ti_{0.48})O_3$(BFO/PZT) multilayer thin films have been prepared on a Pt/Ti/$SiO_2$/Si(100) substrate by chemical solution deposition. BFO single layer, BFO/PZT bilayer and multilayer thin films were studied for comparison. X-ray diffraction analysis showed that the crystal structure of all films was multi-orientated perovskite phase without amorphous and impurity phase. The leakage current density at 500 kV/cm was reduced by approximately four and five orders of magnitude by bilayer and multilayer structure films, compared with BFO single layer film. The low leakage current density leads to saturated P-E hysteresis loops of bilayer and multilayer films. In BFO/PZT multlayer film, saturated remanent polarization of $44.3{\mu}C/cm^2$ was obtained at room temperature at 1 kHz with the coercive field($2E_c$) of 681.4 kV/cm.
Ar가스 분위기에서 PLD방법으로 제작된 TiNi박막의 조성 및 결정성에 관한 연구
차정옥,신진호,여승준,안정선,남태현,Cha, J.O.,Shin, C.H.,Yeo, S.J.,Ahn, J.S.,Nam, T.H. 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.2
Ti-50 at. % Ni 합금 타깃으로 PLD(pulsed laser deposition)방법을 사용하여 TiNi 형상기억합금 박막을 제작하였다. Ar분위기(200 mTorr)와 고진공분위기($5{\times}10^{-6}\;Torr$)에서 제작한 TiNi 박막의 조성 및 결정성의 변화를 조사했으며, 박막의 조성은 에너지 분산 엑스선 분광 분석(EDXS)을 이용하여 조사하였고, 박막의 결정성은 엑스선 회절장치(XRD)를 이용하여 조사하였다. 박막의 조성은 기판과 타깃의 거리에 의존되었지만, 기판의 온도와는 무관함을 알 수 있었으며, Ar 분위기에서 플룸 안쪽에 기판이 위치하였을 때 조성 제어가 용이함을 알 수 있었다. 또한, Ar 가스 분위기에서 증착 된 TiNi 박막은 고진공분위기에서 증착된 박막보다 더 낮은 온도(약 $400^{\circ}C$)에서 in situ로 결정화됨을 알 수 있었다. 이들 결과는, PLD방법으로 TiNi 형상기억합금 박막을 제작할 때 분위기 가스의 압력이 결정화 온도를 낮추어 주는 중요한 역할을 할 수 있음을 시사한다. TiNi shape memory alloy(SMA) was fabricated by PLD(plused laser deposition) using equiatomic TiNi target. Composition and crystallization of TiNi thin films which were fabricated in ambient Ar gas(200m Torr)and vacuum($5{\times}10^{-6}\;Torr$) were investigated. Composition of TiNi thin films was characterized by energy-dispersive X-ray spectrometry (EDXS) and crystallization was confirmed by X-ray diffraction (XRD). The composition of films depends on the distance between target and substrate but does not sensitively depend on the substrate temperature. It is found that the composition of films can be easily controlled when substrate is placed inside plume in ambient Ar gas. It is also found that the in situ crystallization temperature ($ca.\;400^{\circ}C$) in ambient Ar gas is lowered in comparison with that of TiNi film prepared under vacuum. The low crystallization temperature in ambient Ar gas makes it possible to prepare the crystalline TiNi thin film without contamination.
Multiferroic BiFeO3 Thin Films Prepared by Using a Conventional RF Magnetron Sputtering Method
차정옥,이광배,안정선 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.2
Multiferroic BiFeO3 thin films were deposited on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering using self-made BFO ceramic targets. The influence of the partial pressure of oxygen (P(O2)), as well as the substrate temperature, on the preparation of pure BFO films was studied. BFO thin films with a single perovskite phase were obtained only for a P(O2) of 0.3 mTorr to 1.5 mTorr at a substrate temperature of 400℃, with subsequent annealing at 500℃ in a N2 ambient. The impurity phase rather than perovskite BFO phase could be easily formed due to the excess Bi content for a low P(O2) of 0.1 mTorr. A BFO thin lm having high c-axis orientation could be obtained for a P(O2) of 0.3 mTorr, which has the maximum remanent polarization of 5.2uC/cm2. The leakage current behaviors, as well as the magnetic properties, of the BFO lms are elucidated by using a compositional analysis of Fe3+ and Fe2+ ions from the X-ray photoelectron spectroscopy studies. Multiferroic BiFeO3 thin films were deposited on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering using self-made BFO ceramic targets. The influence of the partial pressure of oxygen (P(O2)), as well as the substrate temperature, on the preparation of pure BFO films was studied. BFO thin films with a single perovskite phase were obtained only for a P(O2) of 0.3 mTorr to 1.5 mTorr at a substrate temperature of 400℃, with subsequent annealing at 500℃ in a N2 ambient. The impurity phase rather than perovskite BFO phase could be easily formed due to the excess Bi content for a low P(O2) of 0.1 mTorr. A BFO thin lm having high c-axis orientation could be obtained for a P(O2) of 0.3 mTorr, which has the maximum remanent polarization of 5.2uC/cm2. The leakage current behaviors, as well as the magnetic properties, of the BFO lms are elucidated by using a compositional analysis of Fe3+ and Fe2+ ions from the X-ray photoelectron spectroscopy studies.
차정옥(J. O. Cha),안정선(J. S. Ahn),이광배(K. B. Lee) 한국진공학회(ASCT) 2010 Applied Science and Convergence Technology Vol.19 No.1
BiFeO₃(BFO)/Pb(Zr0.52Ti0.48)O₃(PZT) bilayer와 multilayer의 다층구조를 만들어 전기적 특성을 측정하여 같은 두께의 BFO 단층박막과 비교해 보았다. BFO와 PZT 용액을 이용하였으며 chemical solution deposition 방법으로 Pt/Ti/SiO₂/Si(100) 기판위에 각 박막을 증착하였다. X-ray diffraction 분석을 통해 모든 박막이 다배향(multi-orientation) 페로브스카이트(perovskite) 구조를 가졌음을 확인하였다. BFO/PZT Bilayer와 multilayer 박막들은 BFO 단층박막의 비해 누설전류 값이 500 ㎸/㎝에서 약 4, 5차수 정도 감소했으며, 이로 인해 BFO/PZT 다층박막의 강유전체 특성이 크게 향상되었다. BFO/PZT multilayer 다층구조 박막의 경우 안정된 이력곡선(hysteresis loop)을 나타냈으며, 잔류 분극(remanent polarization)의 값은 44.3μC/㎠이었으며, 항전계(2Ec) 값은 681.4 ㎸/㎝였다. BiFeO₃/Pb(Zr0.52Ti0.48)O₃(BFO/PZT) multilayer thin films have been prepared on a Pt/Ti/SiO₂/Si(100) substrate by chemical solution deposition. BFO single layer, BFO/PZT bilayer and multilayer thin films were studied for comparison. X-ray diffraction analysis showed that the crystal structure of all films was multi-orientated perovskite phase without amorphous and impurity phase. The leakage current density at 500 ㎸/㎝ was reduced by approximately four and five orders of magnitude by bilayer and multilayer structure films, compared with BFO single layer film. The low leakage current density leads to saturated P-E hysteresis loops of bilayer and multilayer films. In BFO/PZT multlayer film, saturated remanent polarization of 44.3μC/㎠ was obtained at room temperature at 1 ㎑ with the coercive field(2Ec) of 681.4 ㎸/㎝.