• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.293-295
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• 1994

Barium Titanate ($BaTiO_3$) is one of the few titanateds which is cubic at room temperature. It has the perovskite structure, high dielectric constant (${\varepsilon}_r=300$) and a small temperature coefficient of resistance due to it's Low transition temperature ($Tc=120^{\circ}c$). PTCR (Positive Temperature Coefficient of Resistivity) thermistor in thin film $BaTiO_3$ system was prepared by using radio frequency (13.56MHz) and BC magnetron sputter equipment. Polycrystalline, and surface structure characteristics of the specimens were measured by X-ray diffraction (D-Max3, Rigaku, Japan), SEM(Scanning Electron Microscopy: M. JSM84 01, Japan), respectively. Temperature at below $600^{\circ}C$, $1000^{\circ}C$ to $700^{\circ}C$, and above $1100^{\circ}C$ for spotted $BaTiO_3$ thin films showed the amorphous, degree of crystal growth, and polycrystalline, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.528-531
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• 2000

Deposition of PZT with UV laser ablatio was applied for realization of thin film sensors and actuators. Deposition rate of more than 20nm/min was attained by pulsed KrF excimer laser deposition, which is fairly better than those obtained by the other methods. Perovskite phase was obtained at room temperature deposition with Fast Atom Beam(FAB) treatment and annealing. Smart MEMS(Micro electro-mechanical system) is now a suject of interest in the field of micro optical devices, micro pumps, AFM cantilever devices etc. It can be fabricated by deposition of PZT thin films and micromachining. PZT films of more than 1 micron thickness is difficult to obtain by conventional methods. This is the reason why we applied excimer laser ablation for thin film deposition. The remanent polarization Pr of 700nm PZT thin film was measured, and the relative dielectric constant was determined to about 900 and the dielectric loss tangent was also measured to be about 0.04. XRD analysis shows that, after annealing at 650 degrees C in 1 hour, the perovskite structure would be formed with some amount of pyrochlore phase, as is the case of the annealing at 750 degrees C in 1 hour.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 학술대회 및 기술세미나 논문집 디스플레이 광소자
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• pp.74-75
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• 2006

We have investigated dielectric properties depending on temperature in organic light-emitting diodes using 8-hydroxyquinoline aluminum ($Alq_3$) as an electron transport and emissive material. We analyzed the dielectric properties of organic light-emitting diodes using characteristics of impedance. he Impedance characteristics was measured complex impedance Z and phase $\theta$ in the temperature range of 10 K to 300 K. We obtained complex electrical conductivity, dielectric constant and loss tangent ($tan{\delta}$) of the device at room temperature. From these analyses, we are able to interpret a conduction mechanism and dielectric properties contributed by an interfacial and orientational polarization.

• Transactions on Electrical and Electronic Materials
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• 제11권1호
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• pp.29-32
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• 2010

In this study, transparent and conductive Al-doped zinc oxide (AZO) films were prepared on a glass substrate by an radio frequency (RF) magnetron sputtering method using a 150-nm-thick AZO target (Al: 2 wt.%) at room temperature. We investigated the effects of RF power between 100-350 W (in steps of 50 W) on the structural, electrical, and optical properties of the AZO films. The thickness and cross-sectional images of the films were observed by field emission scanning electron microscopy. The thicknesses of all films were kept constant at 150 nm and grown on a glass substrate. The grain sizes of the AZO films were determined with the X-ray diffraction by using the Scherrer' equation, and their electrical properties were investigated using a Hall effect electronic transport measurement system. The transmittance of the AZO films was also measured by an ultraviolet-visible spectrometer.

• 한국전기전자재료학회논문지
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• 제20권4호
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• pp.342-347
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• 2007

$Bi_6Mg_2Nb_4O_{21}(BMN)$ thin films were deposited at various substrates by sputtering system for embedded capacitor applications. BMN thin films deposited at room temperature are manufactured as MIM(Metal/Insulator/Metal) structures. Dielectric properties and leakage current density were investigated as a function of various substrates and thickness of BMN thin films. Leakage current density of BMN thin films deposited on CCL(Copper Clad Laminates) showed relatively high value ($1{\times}10^{-3}A/cm^2$) at an applied field of 300 kV/cm on substrates, possibly due to relatively high value of roughness(rms $50{\AA}$) of CCL substrates. 100 nm-thick BMN thin films deposited on Cu/Ti/Si substrates showed the capacitance density of $300 nF/cm^2$, a dielectric constant of 32, a dielectric loss of 2 % at 100 kHz and the leakage current density of $1{\times}10^{-6}A/cm^2$ at an applied field of 300 kV/cm. BMN capacitors are expected to be promising candidates as embedded capacitors for printed circuit board(PCB).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.190-190
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• 2010

Zinc oxide is the most attractive material due to the large direct band gap (3.37 eV), excellent chemical and thermal stability, and large exciton binding energy (60 meV). Recently, ZnO nanorods were used as the high efficient antireflection coating layer of solar cells based on silicon (Si). In this reports, we studied the effects of rapid thermal annealing (RTA) treatment on optical properties of ZnO nanorods. For fabrication of ZnO nanorods, there are many methods such as hydrothermal method, sol-gel method, and metal organic chemical vapor deposition method. Among of them, we used the conventional wet chemical method which is simple and low temperature growth. In order to synthesize the ZnO nanorods, the ZnO films were deposited on Si substrate by RF magnetron sputtering at room temperature and the samples were dipped to aqua solution containing the zinc nitrate and hexamethylentetramines (HMT). The synthesis process was achieved in keeping with temperature of $90-95^{\circ}C$ and under constant stirring. The morphology of ZnO nanorods on glass and Si was characterized by scanning electron microscopy. For the analysis of antireflection performance, the reflectance and transmittance were measured by spectrophotometer. And for analyzing the effects of RTA treatment on ZnO nanorods, crystalline properties were investigated by X-ray diffraction measurements and optical properties was estimated by photoluminescence spectra.

• 한국재료학회지
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• 제8권4호
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• pp.323-327
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• 1998

재충전이 가능한 Li/PEO-$LiClO_{4}$-PC/$LIMn_2O_4$구조의 전고상 전지를 제작하였다. $LIMn_2O_4$박막은 RF 마그네트론 스퍼터링 법으로 제작하였으며, $750^{\circ}C$ 부근에서의 급속열처리를 통하여 스피넬 상으로 결정화시킬 수 있었다. 상온 충.방전 시험을 행한 결과, 평균 전압 4V(vs. Li)의 평탄한 방전 전압과 우수한 재충전 능력을 나타내었다.

• 한국정밀공학회지
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• 제18권12호
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• pp.167-176
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• 2001

The effects of heat treatments and testing temperatures on the mechanical properties of Invar materials were investigated through experiments, which call influence the formability in metal forming fields. Annealing temperatures were changed from $900^{\circ}C$ to $1200^{\circ}C$ with an increment of $100^{\circ}C$ under two different furnace atmosphere(vacuum and H$_2$gas). Microstructure and hardness tests were performed for annealed specimens at room temperature(RT) and tensile tests were also performed by changing annealing temperatures as well as testing temperatures from RT to $300^{\circ}C$. The grain size of annealed materials increased with increasing annealing temperature, while micro-hardness distributions showed almost same hardness values regardless of annealing temperatures. Strength ratio (tensile/yield strength), which influences the forming characteristics of sheet metal, remained almost constant for various experimental conditions in case of unannealed specimens. However, it showed increasing tendency with increasing both annealing and testing temperatures, particularly at the testing temperature higher than $200^{\circ}C$. Therefore it can be concluded that press formability of fully-annealed Invar material can be improved by warm forming technique.

• Membrane and Water Treatment
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• 제9권2호
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• pp.79-85
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• 2018

In this work, batch adsorption of anionic dye acid green-25 (AG-25) from aqueous solution has been carried out at room temperature using anion exchange membrane (DF-120B) as a noval adsorbent. The effect of various experimental parameters such as contact time, membrane dosage, ionic strength and temperature on the adsorption of dye were investigated. Kinetic models namely pseudo-first-order, pseudo-second-order, Elovich, liquid film diffusion, Bangham and modified freundlich models were employed to evaluate the experimental data. Parameters like adsorption capacities, rate constant and related correlation coefficients for every model are calculated and discussed. It showed that adsorption of AG-25 onto DF-120B followed pseudo-first-order rate expression. Thermodynamic study indicates that adsorption of AG-25 onto DF-120B is an exothermic and spontaneous process.

• Bulletin of the Korean Chemical Society
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• 제18권9호
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• pp.961-965
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• 1997

1H NMR spectra of 3,3-dimethylpiperidine (1) at -70 to 30 ℃ exhibit gradual change from slow to rapid exchange between two alternate chair forms. The exchange rate constant was determined as a function of temperature by simulating the line shape of the signal from the two methyl groups using the modified Bloch equations. The resulting free energy of activation is ΔG* = 44.4±1.9 kJ mol-1 at 298 K. The 1H NMR spectrum of a D2O or dimethylsulfoxide-d6 (DMSO-d6) solution containing 1 and [SiW11CoⅡO39]6- exhibits separate signals for the free ligand and the complex, indicating that the ligand exchange is slow on the NMR time scale. In D2O the piperidine ring is frozen as a chair form even at room temperature with the cobalt ion bonded to the axial position of the nitrogen atom. When DMSO-d6 is added to the D2O solution, the NMR spectral change suggests that a rapid exchange occurs between the chair form and another conformer. It is proposed that the conformation of ^b1^b coordinated to [SiW11CoⅡO39]6- in DMSO-d6 is close to a twist form.