졸-겔법으로 백금 기판위에 제조된 PLZT 박막의 구조적, 전기적 특성변화

오영제,김태송,정형진 한국세라믹학회 1994 한국세라믹학회지 Vol.31 No.2

The spin-casted PLZT(9/65/35) thin films through polymeric sol-gel process were prepared on Pt substrate. The crack-free, uniform and dense films were obtained by post-annealing at the temperature between 35$0^{\circ}C$ and $700^{\circ}C$. The composite structure mixed together with large grains called "rosette" and surrounding small grains were observed on the films annealed over $600^{\circ}C$. Pyrochlore phase was completely changed to perovskite phase above $600^{\circ}C$ with the increase of annealing temperature. Dielectric constant (k) was larger with the increase of film thickness and annealing temperature. from the measurements of dielectric constant as a function of measuring temperature, it was also observed that Curie temperature was shifted to higher temperature with the increase of film thickness and annealing temperature. The pyroelectric coefficient(P) of 10 times coated film annealed at $700^{\circ}C$ was 65 $\mu$C/$\textrm{cm}^2$.K.$.K.

졸-겔법에 의한 PLZT 합성과 강유전성 박막 제조

오영제,김정기,주기태,현상훈,정형진 한국세라믹학회 1992 한국세라믹학회지 Vol.29 No.11

Lead lanthanum zirconate titanate (PLZT, 6/65/35) powders, crack-free and dense thin films have been prepared by polymeric sol-gel process. Pyrolysis of the gel, crystallization and optical transmittance behavior of the PLZT thin film onto sapphire substrate have been studied. Esterification occurs during synthesis of PLZT complexation. Crystalline Pb phase was transiently formed near 450$^{\circ}C$. Content of perovskite phase in the films were increased with increasing thickness of film, but the kinetics of formation of perovskite phase in films was slower than that of powders. Transmittance of the films was decreased with increasing the temperature of heat treatment. Ferroelectric hysteresis loop measurements indicated increments of remanent polarization and coercive field for plenty more of perovskite phase.

SIP-3 한약 처방 및 도네페질의 병용 치료: 아밀로이드 베타로유도된 알츠하이머병 생쥐 모델에서의 NGS 연구

오영제,송수진,류천봉,손태권,김근우,구병수 대한한방신경정신과학회 2019 동의신경정신과학회지 Vol.30 No.4

Objectives: Alzheimer’s disease (AD) is a complex disease accompanied by slow impairment of memory and coordination leading to behavioral changes. To date, the only treatment option is to delay the progress of the disease. The purpose of this study was to investigate the synergistic effects of combination treatment with donepezil and three herbal extracts SIP-3 in the AD mouse model induced by amyloid- β (Aβ). Methods: We tested SIP-3 extracts for the cytotoxicity on Aβ-treated SH-SY5Y cells. Then the synergistic effects of SIP-3 and donepezil were evaluated in the AD mouse model using animal experiments and the next generation sequencing (NGS) study. Results: We found that co-treatment with SIP-3 extracts and donepezil increased the viability in Aβ- treated SH-SY5Y cells. The beneficial effects of the co-treatment were also observed in the Aβ-induced AD mouse model. The NGS study was performed to show that the co-treatment of SIP-3 and donepezil restored the disease phenotype closely to the normal level in the AD mouse model in terms of mRNA expression. However, the phenotypes were only partially restored. Conclusions: This study suggests that the combination treatment has a potential to be used for the treatment of AD. However, longer periods of treatment may be required.

Determination of Hydroxyapatite Precipitation Condition from the $Ca-PO_4-H_2O$ System

오영제,Oh, Young-Jei 한국분석과학회 2000 분석과학 Vol.13 No.2

수산화물, 탄산염 및 수산화아파타이트(HAp)의 형성과 해리는 용액의 pH에 따라 달라지며 $Ca-PO_4-H_2O$계로부터 균질하고 미세한 HAp, $Ca_{10-x}(HPO_4)_x(PO_4)_{6-x}(OH)_{2-x}(x=0)$, 세라믹 분말을 제조하는데 매우 중요한 인자가 된다. 각 복합이온의 용해도는 pH와 직선적인 관계에 있으므로 용해도 도형은 수산화물, 탄산염 및 수산화아파타이트(HAp)의 평형상수와 용해도적으로부터 계산된 대수 몰농도로 그릴 수 있다. $Ca-PO_4-H_2O$계로부터 $25^{\circ}C$에서 단일상의 $Ca_{10-x}(HPO_4)_x(PO_4)_{6-x}(OH)_{2-x}(x=0)$ 분말을 제조하기 위한 최적의 pH조건은 이론적인 고찰 결과 $10.5{\pm}0.5$로 결정되었다. 실온에서 제조하여 $80^{\circ}C$에서 건조시킨 HAp분말은 75nm의 입자크기를 갖는 미세한 응집분말 이었으며, $1,000^{\circ}C$에서 하소시킨 HAp분말은 450nm 크기의 거의 균질한 형태의 분말을 얻었다. HAp분말들이 응집되어 있었지만 소결후 미세구조는 양호하여 우수한 기계적 특성을 보유하였다. The formation and dissolution of hydroxides, carbonates and hydroxyapatite (HAp), which depend on the pH of solution, are important factor for the preparation of homogeneous and fine HAp, $Ca_{10-x}(HPO_4)_x(PO_4)_{6-x}(OH)_{2-x}(x=0)$, ceramic powder from the $Ca-PO_4-H_2O$ system. Since the solubility of each complex ion is a linear function of pH, the solubility diagram can be obtained by plotting the logarithmic molar concentrations calculated from the values of the equilibrium constants and solubility products for hydroxides, carbonates, and hydroxyapatite. The optimum pH condition for the formation of single phase $Ca_{10-x}(HPO_4)_x(PO_4)_{6-x}(OH)_{2-x}(x=0)$ powder in $Ca-PO_4-H_2O$ system at $25^{\circ}C$ was estimated as $10.5{\pm}0.5$ through the theoretical consideration. The HAp powder dried at $80^{\circ}C$ showed a fine agglomerated particles with a size of 75 nm. The HAp powder calcined at $1,000^{\circ}C$ consisted of nearly homogeneous particles with a size of 450 nm. Even though the dried HAp particles consisted of agglomeration, mechanical properties were superior due to fine microstructure after sintering.

Preparation of Ti-doped ZnO transparent conductive thin films by PLD method

오영제,심광보,이현우,Bong Geun Choi 한양대학교 세라믹연구소 2005 Journal of Ceramic Processing Research Vol.6 No.1

Ti-doped ZnO thin films were prepared on a soda-lime glass substrate without any post heat treatment by a pulsed laser deposition (PLD) method. Processing parameters such as deposition substrate temperature, the amount of Ti-doping and oxygen flow rate were investigated. It was found that the Ti-doped ZnO thin films exhibited a strongly preferred orientation along a C-axis (002) plane and their structural, electrical and optical properties depended strongly on these parameters. Transparent conducting ZnO oxide thin films with 1 mol% Ti content formed under the conditions of a substrate temperature of 100oC in an oxygen flow rate of 10 sccm showed an electrical resistivity of 3.3 × 10−2 Ωcm, a mean optical transmittance of 92.3% with a thickness of 480 nm.

유리기판에 sol-gel법으로 제조된 나노입자 Co-ferrite 박막의 특성

오영제,최현석,최세영 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.5

Cobalt ferrite thin films on Corming glass substrate were fabricated by a sol-gel method. Cobalt ferrite thin films with the grain size of 20-35 nm and thickness of 50nm were obtained. Rapid thermal annealing (RTA) and Annealing processes were adopted for comparison of characteristics of the films. Coercivity values were changed with thermal condition and magnetization values were increased as a function of soaking time. With prolonged soaking time, however, it was decreased because of the diffusion of cations from the glass substrate. The RTA process in preparation of cobalt ferrite thin film was the effective way to prevent and to form a single spinel phase in reduced soaking time. The film heated at 600$^{\circ}C$ for 30 minutes by RTA had coercivity of 2,600 Oe, saturation magnetization 460 emu/㎤, and Mr$.$$\delta$ of 1.43 memu/$\textrm{cm}^2$.

세라믹스와 반도체를 이용한 방사선 센서

오영제,주관식 한국세라믹학회 2005 세라미스트 Vol.8 No.4

″Fusion″그것이 우리의 선택일까\ulcorner

오영제 한국세라믹학회 2002 세라미스트 Vol.5 No.1

Structure and properties of Co doped TiO2 thin films on Si(100) by a pulsed laserdeposition method

오영제,최덕균,이재열,W.Y. Lee 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.1

We report on the crystal structure and magnetic properties of CoxTi1-xO2 thin films (0.03 ≤ x ≤ 0.07), grown on Si(100) substrates by pulsed laser deposition (PLD) as a function of Co concentration, substrate temperature, oxygen flow rate and working pressure. The crystal structure exhibiting ferromagnetism at room temperature was found to originate from the anatase phase in the CoxTi1-xO2 thin films, which grew well on Si substrates. The saturation magnetization (Ms) was observed to increase with increasing Co concentration in the range x = 3-7%. The CoxTi1-xO2 film with x = 7% exhibits Ms = 5.31 emu/ cm3 and Hc = 92.5 Oe. The magnetic moment in the films is likely to depend upon the extent of crystallization of the anatase phase, which is related to the resistivity of the films.

Dispersion stability and characterization of lead-free transparent dielectric glass frit

오영제,Jin-Won Lee 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.5

The effect of solvents and dispersants on the slurry dispersion stability in tape castings of lead-free transparent Bi2O3-ZnOBaO- Al2O3 dielectric layers for plasma display panel (PDP) were studied. A comparative study of mechanical and optical properties of the green sheets fabricated with and without dispersion stabilizers was performed. The optimum dispersion stability, which was due to steric stabilization, was observed for a 1.5 wt% polyethylene glycol solution in methanol with 33.3% solid loading; the corresponding green sheet demonstrated the best mechanical and optical performance after firing. The green sheet prepared by dispersion stability had a stronger tensile strength of 6.6 kg/cm²(6.47MPa) and more uniform microstructure than the green sheet prepared without dispersion stability (tensile strength of 4.6 kg/cm²(4.51MPa)). The optimum result was obtained by fire processing a green sheet at 505℃ for 30 minutes; the dielectric layer obtained with 30 μm thickness on sodalime glass substrate had a transmittance of 81% at a reference wavelength of 550 nm without a yellowing phenomenon.