• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.397-397
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• 2013

The electrical, electronic, optical properties and the local structure of Nickel Oxide (NiO) thin film have been investigated by X-ray photoelectron spectroscopy (XPS), Reflection Electron Energy Loss Spectroscopy (REELS), UV-spectrometer,Hall Effect measurement and X-ray absorption spectroscopy (XAS). The XPS results show that the Ni 2p spectra for all films consist of $Ni2p_{3/2}$ at around 854.5 eV which indicate the presence of Ni-O bond from NiO phase and for the annealed film at temperature above $200^{\circ}C$ shows the coexist Ni oxide and Ni metal phase. The REELS spectra showed that the band gaps of the NiO thin films were abruptly decreased with increasing temperature. The values of the band gaps are consistent with the optical band gaps estimated by UV-Spectrometer. The optical transmittance spectra shows that the transparency of NiO thin films in the visible light region was deteriorated with higher temperature due to existence of $Ni^0$. Hall Effect measurement suggest that the NiO thin films prepared at relatively low temperatures (RT and $100^{\circ}C$) are suitable for fabricating p-type semiconductor which showed that the best properties was achieved at $100^{\circ}C$, such as a low resistivity of $7.49{\Omega}.cm$. It can be concluded that the annealing process plays a crucial role in converting from p type to n type semiconductor which leads to reducing electrical resistivity of NiO thin films. Furthermore, the extended X-ray absorption fine structure (EXAFS) spectrum at the Ni K-edge was used to address the local structure of NiO thin films. It was found that the thermal treatments increase the order in the vicinity of Ni atom and lead the NiO thin films to bunsenite crystal structure. Moreover, EXAFS spectra show in increasing of coordination number for the first Ni-O shell and the bond distance of Ni-O with the increase of substrate temperature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.9
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• pp.931-935
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• 2012

In this study, we fabricate and investigate low-temperature solid oxide fuel cells with a ceramic substrate/porous metal/ceramic/porous metal structure. To realize low-temperature operation in solid oxide fuel cells, the membrane should be fabricated to have a thickness of the order of a few hundreds nanometers to minimize IR loss. Yttrium-doped barium zirconate (BYZ), a proton conductor, was used as the electrolyte. We deposited a 350-nm-thick Pt (anode) layer on a porous substrate by sputter deposition. We also deposited a 1-${\mu}m$-thick BYZ layer on the Pt anode using pulsed laser deposition (PLD). Finally, we deposited a 200-nm-thick Pt (cathode) layer on the BYZ electrolyte by sputter deposition. The open circuit voltage (OCV) is 0.806 V, and the maximum power density is 11.9 mW/$cm^2$ at $350^{\circ}C$. Even though a fully dense electrolyte is deposited via PLD, a cross-sectional transmission electron microscopy (TEM) image reveals many voids and defects.

• Journal of the Korean Chemical Society
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• v.17 no.5
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• pp.337-345
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• 1973

The nonstoichiometry of the iron oxide system has been studied by analyzing the weight loss of a sample, measured by using a quartz microbalance, in a temperature range from $0^{\circ}C$ to $1200^{\circ}C$ under oxygen pressures from $10^{2}mmHg$ to $10^{-4}mmHg$. The Y values of the formula, $FeO_{1+\gamma}$, that have been obtained by this means for various conditions of temperature and pressure in this range are considered to be more accurate than values obtained by methods requiring thste quenching of the sample before measurements are made. The plots of log Y vs $log PO_2$ (or $log Y =_n log PO_2$) show linearity and n calculated from the slope of the plot is about 1/10 at $1000^{\circ}C$, indicating a difference between the nonstoichiometric and oxidation mechanisms. The condition for the formation of stoichiometric FeO was determined to be $1200^{\circ}C$ under $10^{-3}mmHg$ of $O_2$ and the composition of the oxide under standard conditions was $FeO_{1.11185}$. As in general more oxygen dissolves into the oxide system at lower temperatures and higher oxygen pressures, the deviation from stoichiometric FeO is greater under those conditions. A comparison of the change in conductivity of the sample indicates that full phase transition does not take place with conductivity transition.

• Journal of the Korean Chemical Society
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• v.10 no.1
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• pp.32-42
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• 1966

The electrolysis of tungstic oxide dissolved in the bath of calcium chloride and calcium oxide was studied to produce metallic tungsten using carbon as anode and iron as cathode in the temperature range of 900^{\circ}$ to $1200^{\circ}C$. The binary phase diagrams $CaCl_2$-CaO and $CaCl_2-CaWO_4$ systems were constructed to determine the suitability of bath composition and the range of temperatures for the electrolysis. As $WO_3$ reacted with $CaCl_2$ to form oxychloride in the fused salt, the addition of the proper amount of CaO was necessary to avoid the loss of $WO_3$. The optimum compositions of fused bath were $CaCl_2$ 100 parts, CaO and $WO_3$ each 10 to 20 parts, with the CaO, $WO_3$ ratio greater than unity, to keep freezing point low and to prevent the vaporization of $CaCl_2$. The observed decomposition voltage at which $WO_3$ decomposes to W and CO was-0.1 volt, whereas the calculated was -0.3 volt. Metallic tungsten deposited at the cathode reacted easily with CO formed secondarily at the anode surface, to form WC below $1050^{\circ}C$, so that the cell temperature should be above $1050^{\circ}C$. The effects of cathode current densities on current efficiency were minor in the range of 1 to 5 $amp/cm^2$.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.812-822
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• 2006

This study amis to investigate the functional analysis of anode and cathode materials in Anode supported Solid Oxide Fuel Cell. The concentration polarization of single cell was investigated with CFD (Computational Fluid Dynamics) method for the case of the different morphology by using four types of unit cell and discussed to reduce the concentration polarization. The concentration polarization at anode side effected the voltage loss in Anode supported Solid Oxide Fuel Cell and increased contact areas between fuel gas and anode side could reduce the concentration polarization. For intermediate temperature operation, Anode-supported single cells with thin electrolyte layer of YSZ (Yttria-Stabilized Zirconia) were fabricated and short stacks were built and evaluated. We also developed diesel and methane autothermal reforming (ATR) reactors in order to provide fuels to SOFC stacks. Influences of the $H_2O/C$ (steam to carbon ratio), $O_2/C$ (oxygen to carbon ratio) and GHSV (Gas Hourly Space Velocity) on performances of stacks have been investigated. Performance of the stack operated with a diesel reformer was lower than with using hydrogen as a fuel due to lower Nernst voltage and carbon formation at anode side. The stack operated with a natural gas reformer showed similar performances as with using hydrogen. Effects of various reformer parameters such as $H_2O/C$ and $O_2/C$ were carefully investigated. It is found that $O_2/C$ is a sensitive parameter to control stack performance.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.2
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• pp.127-139
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• 2023

In this study, minoxidil, which is well known as a pharmaceutical raw material, and diaminopyrimidine oxide (DAO), which is a cosmetic raw material, were used as active ingredients to evaluate the physical properties of niosomes and compare the skin penetrations of artificial skin. To prepare niosomes of the size of nanoparticles, a high pressure homogenization method was used, and physical properties were evaluated with a zetasizer. The particle size of the noisome including the active ingredient was measured to be 99 to 123 nm according to HLB, and the zeta potential was measured in the range of -60 to -81 mV. Through DSC (differential scanning colorimetry), it was confirmed that minoxidil, a crystalline component, was uniformly dissolved in an amorphous state in niosomes. In order to confirm and compare skin penetration, it was measured by the in vitro Franz diffusion cell method, and the niosome formulation showed 3.4 times higher penetration for minoxidil and 11.1 times higher penetration for DAO than the control gel formulation. In addition, when comparing the skin penetration of minoxidil niosome and DAO niosome, a similar trend was shown, and the penetration amount of DAO was relatively high. The shapes of the niosome formulations with different HLB values were observed using Cryo-TEM, and it was confirmed that vesicles were formed in all of them and that they were intermediate between SUV (small unilamella vesicle) and LUV (large unilamella vesicle). Through this study, minoxidil, an effective drug for hair loss, and DAO, a cosmetic raw material, can be effectively delivered to the skin by encapsulating them in a noisome formulation.

• Journal of Hydrogen and New Energy
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• v.16 no.3
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• pp.277-283
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• 2005

Pretreatment procedure was investigated into brucite powders for mineral carbonation materials. Higher magnesium content was found from brucite powders and weight loss due to hydroxy group(-OH) elimination, explained by FT-IR spectra, was found after pretreatment. X-ray diffraction results showed that the crystallographic changing of brucite into magnesium oxides during pretreatment. XPS core spectra also showed chemical transformation of magnesium ingredient from hydroxides to oxide.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.104-104
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• 2009

In this study, both structural, dielectric and piezoelectric properties of the NKN-0.96BNT-0.04BT ceramics were investigated. All samples of the NKN-0.96BNT-0.04BT ceramics were fabricated by conventional mixed oxide method with Pt electrodes. We report the improved dielectric and piezoelectric properties in the perovskite structure composed of the NKN, BNT and the BT ceramics. We investigated the effects of NKN, BT on the structural and electrical properties of the NKN-0.93BNT-0.07BT ceramics. The dielectric properties and piezoelectric properties of the NKN-0.93BNT-0.07BT ceramics were superior to those of single composition NKN, NKN-BNT and those values for the NKN-0.93BNT-0.07BT ceramics were 861 and 1.12%.

• ETRI Journal
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• v.32 no.2
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• pp.342-344
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• 2010

A novel, maskless, low-volume bumping material, called solder bump maker, which is composed of a resin and low-melting-point solder powder, has been developed. The resin features no distinct chemical reactions preventing the rheological coalescence of the solder, a deoxidation of the oxide layer on the solder powder for wetting on the pad at the solder melting point, and no major weight loss caused by out-gassing. With these characteristics, the solder was successfully wetted onto a metal pad and formed a uniform solder bump array with pitches of 120 ${\mu}m$ and 150 ${\mu}m$.

• KEPCO Journal on Electric Power and Energy
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• v.3 no.1
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• pp.35-39
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• 2017

Recently, the public opinion is growing that the main cause of greenhouse gas, fine dust and nitrogen oxide, sulfuric acid emission is coal-fired power plant, and now the decommission or conversion to other clean fuel is being demanded. However, it is a huge national loss to decommission coal-fired power plant with remaining life, and also simple fuel converting to natural gas will lead to drastic rise on power generating cost. Therefore, this study aims to provide the analysis result about the reduction effect of $CO_2$, environment emission, and to influence to power plant performance and facilities when repowering with adding gas turbine is applied to domestic aged coal-fired power plant.