• 한국결정성장학회지
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• 제12권4호
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• pp.178-183
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• 2002

용매제로서 polypropanediol을 사용한 sol-gel법으로, La의 함량을 1, 2, 5, 7 ㏖%로 변화시킨 PLZT(x/50/50) 박막을 제조하고 La 함량에 따른 유전특성의 변화를 연구하였다. 제조한 sol을 사용하여 $Pt/Ti/SiO_2$/Si 위에 10회 코팅한 후, 560~$600^{\circ}C$까지 10분간 열처리하여 600nm 두께의 박막을 얻을 수 있었다 $560^{\circ}C$ 이상에서는 조성에 관계없이 perovskite 단일 상만이 나타났고, La 함량이 증가함에 따라 입자 크기가 증가하였다. 모든 조성의 박막에서 열처리 온도가 증가함에 따라 유전상수 및 잔류분극 값이 증가되었으며 $600^{\circ}C$에서 열처리한 박막이 가장 우수한 유전 특성을 나타내었다. $600^{\circ}C$에서 열처리한 박막에서 La함량이 증가함에 따라 잔류분극, 항전계, 유전상수 모두 감소하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.262-265
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• 2007

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. The polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV. In the next step, we examine the technique when the dual-polarization data are split into two multi-look Images.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.157-160
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• 2007

The catalyst layer of a proton exchange membrane (PEM) fuel cell is a mixture of polymer, carbon, and platinum. The characteristics of the catalyst layer play critical role in determining the performance of the PEM fuel cell. This research investigates the role of catalyst layer composition using a Central Composite Design (CCD) experiment with two factors which are Nafion content and carbon loading while the platinum catalyst surface area is held constant. For each catalyst layer composition， polarization curves are measured to evaluate cell performance at common operating conditions, Electrochemical Impedance Spectroscopy (EIS), and Cyclic Voltammetry (CV) are then applied to investigate the cause of the observed variations in performance. The results show that both Nafion and carbon content significantly affect MEA performance. The ohmic resistance and active catalyst area of the cell do not correlate with catalyst layer composition, and observed variations in the cell resistance and active catalyst area produced changes in performance that were not significant relative to compositions of catalyst layers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.313-316
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• 2003

The lead zirconate titanate, $Pb(Zr_{0:52}Ti_{0:48})O_3$, films of $0.5\;{\mu}m,\;1\;{\mu}m$ and $2\;{\mu}m$ thickness were fabricated on $Pt/Ti/SiO_2/Si$ substrate by the rf magnetron sputtering method. The PZT films were annealed using by a rapid thermal annealing (RTA) method. The thickness dependence of the film structure, dielectric properties, Polarization-electric field hysteresis loops and capacitance-voltage characteristics were investigated over the thickness range of $0.5\;{\mu}m,\;1\;{\mu}m$ and $2\;{\mu}m$. According to the XRD patterns of the films, (110) peak intensity increases with film thickness increased. The increase of PZT films thickness leads to the decrease of the remanent polarization and the dielectric constant.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.155-158
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• 2002

Eu-doped lead zirconium titanate $Pb_{1.1}(Zr_{0.3}Ti_{0.7})O_{3}$ thin films on the Pt/Ti/$SiO_2$/Si substrates prepared by a metalorganic decomposition (MOD) method. The effect on the structural and electrical properties of the films measured according to Eu content. Eu-doping altered significantly the dielectric and ferroelectric properties. The remanent polarization and coercive field decreased with increasing the concentration of Eu content. The dielectric constant and dielectric loss of the film decreased with increasing Eu contents. The 3 mol% of Eu-doped PZT thin film showed large remanent polarization and the fatigue characteristic of the film did not change up to $10^9$ switching cycles.

• 한국전기전자재료학회논문지
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• 제17권2호
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• pp.178-183
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• 2004

PBT thin film was known to be a representative for the FeRAM devices because of its good ferroelectric proporties and the ease in fabricating the thin film. However, there have been several problems such as polarization fatigue and leakage current in memory devices with a PZT thin film. In this study, Sm-dolled PZT thin films were fabricated by the so1-gel method, and their ferroelectric and dielectric proportrics were compared as a function of Sm content. We investigated the effect of the Sm dopant on structural and electrical properties of PZT film. Sm-doped PZT thin films on the Pt/Ti/SiO$_2$/Si substrates have been prepared by a sol-gel method. The remanent polarization and coercive field decreased with increasing the concentration of Sm. The dielectric constant and dielectric loss decreased with Increasing Sm content. Sm-doped PZT thin films showed improved fatigue characteristics compared to the undoped PZT thin film.

• 전자공학회논문지A
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• 제32A권12호
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• pp.48-54
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• 1995

Dielectrically filled parallel-plate waveguide with finite number of periodic slots in its upper plate as a leaky wave antenna is analysed for E-polarization case. The integro-differential equation whose unknown is the slot equivalent magnetic current over the slot is formulated and solved by use of Galerkin's method. From knowledge of the equivalent magnetic current, the propagation constant and radiation pattern for the finite periodic structure are determined and compared with the results of the infinite case. Good correspondence between them is observed.

• Journal of the Optical Society of Korea
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• 제13권4호
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• pp.484-488
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• 2009

We investigate the characteristics of the surface mode formed at the single interface between dual singly negative medium layers. It is shown that the interface can support a mode which has polarization degeneracy and a vanishing propagation constant. That is, this surface mode is a polarization-independent one that does not propagate at all through the interface. The corresponding electric and magnetic field distributions become static along the longitudinal (guiding) direction (but not along the transverse direction) resulting in the formation of transverse-electric/longitudinalmagnetic or transverse-magnetic/longitudinal-electric modes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 춘계학술대회 논문집
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• pp.25-33
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• 1994

Temperature dependences of the remanent polarization $P_{\gamma}$/(T), effective birefringence ㅿｎ(T). dielectric constant K(T) and quadratic electro-optic coefficient R(T) of the two-stage sintered xBa(La$_{1/2}$Nb$_{1/2}$)O$_3$Pb$(Zr_{y}Ti_{1-y})O-{3}$(x=0.085, 0.09, 0.40$\leq$y$\leq$0.70)ceramics were investigated. Increasing the PbZrO$_3$ contents, the crystal structure of a specimen was varied from tetragonal and rhombohedral to cubic, and the phase transition was showed a diffuse phase transition(DPT) characteristics. Especially. in the compositions which located on the PE-FE phase boundary were showed a discrepancy between curie temperature and temperature range which a macroscopic polarization and a effective birefringence were disappeared.

• 한국안전학회지
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• 제19권1호
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• pp.72-76
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• 2004

The $Sr_{0.7}Bi_{2.6}Ta_2O_9$(SBT)thin films are deposited on pt-coated electrode(Pt/$TiO_2/SiO_2/Si$) using a RF magnetron sputtering method. The electrical properties of SBT capacitors with annealing conditions were studied. In the XRD pattern, the SBT thin films in all annealing temperatures had (105) orientation. In the SEM images, Bi-layered perovskite phase was crystallized at $750^{\circ}C$,/TEX> and grains largely grew in oxygen annealing atmosphere. The maximum renanent polarization and the coercive electric field with annealing conditions are 12.40C/$cm^2$ and 30kV/cm, respectively. The dielectric constant and leakage current density with Pt electrode is 340 and 2.13${\times}10^{-10}A/cm^2$, respectively.