• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.269-269
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• 2007

최근 평판디스플레이 산업이 성장함에 따라 품질향상을 위한 연구가 활발히 진행중이며 또한, 부품 소재 개발에 박차를 가하고 있다. 대형 평판디스플레이 중 낮은 전력소모와 광시야각이 우수한 TFT-LCD가 각광받고 있다. TFT-LCD 소자의 투명전극으로 사용되기 위해서는 면저항 10~1k Ohm/sq., 광투과율 85% 이상의 특성이 요구되며 ITO(Indium Tin Oxide의 약자) 타겟을 스퍼터링한 박막이 일반적으로 사용되고 있다. 본 연구에서는 $In_2O_3$ 나노 분말 제조 공법으로 제작된 ITO 타겟을 사용하여 양산성 및 대형화에 적합한 DC 마그네트론 스퍼터 방식으로 투명전극을 제조하였다. 일반적으로 사용되는 고정식 DC 마그네트론 스퍼터 방식은 타겟표면에 재증착(back deposition)되는 저급산화물로 인해 이물 또는 노즐(Nodule) 이 형성되고 이로 인해 비이상적이고 불안정한 방전 플라즈마가 박막의 특성을 저하시킨다. 이러한 문제점을 해결하기 위해 이동식 DC 마그네트론 스퍼터 방식을 채택하였으며 대형 타겟을 이용한 대형화 기판 제작과 안정적인 sputter yield로 인해 uniformity가 우수한 ITO 박막을 제조하였다. ITO 박막의 저면저항 고투과율 특성을 구현하기 위해 공정변수인 산소분압, 전류밀도(DC power) 그리고 증착온도에 따른 ITO 박막의 미세조직과 결정성을 관찰하였으며 전기적 특성을 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.222-222
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• 2010

Transparent semiconductor oxide thin films have been attracting considerable attention as potential channel layers in thin film transistors (TFTs) owing to their several advantageous electrical and optical characteristics such as high mobility, high stability, and transparency. TFTs with ZnO or similar metal oxide semiconductor thin films as the active layer have already been developed for use in active matrix organic light emitting diode (AMOLED). Of late, there have been several reports on TFTs fabricated with InZnO, AlZnSnO, InGaZnO, or other metal oxide semiconductor thin films as the active channel layer. These newly developed TFTs were expected to have better electrical characteristics than ZnO TFTs. In fact, results of these investigations have shown that TFTs with the new multi-component material have excellent electrical properties. In this work, we present TFTs with inverted coplanar geometry and with a novel HfInZnO active layer co-sputtered at room temperature. These TFTs are meant for use in low voltage, battery-operated mobile and flexible devices. Overall, the TFTs showed good performance: the low sub-threshold swing was low and the $I_{on/off}$ ratio was high.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.319.1-319.1
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• 2013

Solid oxide fuel cells (SOFCs) have been recognized as one of emerging renewable energy sources, due to minimized pollutant production and high efficiency in operation. The performance of SOFCs is largely dependent on the electrode polarization which involves the oxidation/reduction in cathodes and anodes along with the charge transport of ions and electronic carriers. Atomic layer deposition is based on the alternate chemical surface reaction occurring at low temperatures with high uniformity and superior step coverage. Such features can be extended into the coating of metal oxide and/or metal layer onto the porous materials. In particular, the atomic layer deposition is can manipulated in controlling the charge transport in terms of triple phase boundaries, in order to control artificially the electrochemical polarization in electrodes of SOFC. The current work applied atomic layer deposition of metal oxides intro the electrodes of SOFCs. The corresponding effect was monitored in terms of the electrochemical characterization. The roles of atomic layer deposition in solid oxide fuel cells are discussed towards optimized towards long-term durability at intermediate temperature.

• Carbon letters
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• v.25
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• pp.14-24
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• 2018

Electrochemical properties and performance of composites performed by incorporating metal oxide or metal hydroxide on carbon materials based on graphene and carbon nanotube (CNT) were analyzed. From the surface analysis by field emission scanning electron microscopy and field emission transmission electron microscopy, it was confirmed that graphene, CNT and metal materials are well dispersed in the ternary composites. In addition, structural and elemental analyses of the composite were conducted. The electrochemical characteristics of the ternary composites were analyzed by cyclic voltammetry, galvanostatic charge-discharge tests, and electrochemical impedance spectroscopy in 6 M KOH, or $1M\;Na_2SO_4$ electrolyte solution. The highest specific capacitance was $1622F\;g^{-1}$ obtained for NiCo-containing graphene with NiCo ratio of 2 to 1 (GNiCo 2:1) and the GNS/single-walled carbon $nanotubes/Ni(OH)_2$ (20 wt%) composite had the maximum specific capacitance of $1149F\;g^{-1}$. The specific capacitance and rate-capability of the $CNT/MnO_2/reduced$ graphene oxide (RGO) composites were improved as compared to the $MnO_2/RGO$ composites without CNTs. The $MnO_2/RGO$ composite containing 20 wt% CNT with reference to RGO exhibited the best specific capacitance of $208.9F\;g^{-1}$ at a current density of $0.5A\;g^{-1}$ and 77.2% capacitance retention at a current density of $10A\;g^{-1}$.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.3
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• pp.201-207
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• 2004

Redox characteristics of metal oxide for hydrogen production by thermochemical water-splitting were investigated. $CuFe_2O_4$ as a redox pair that had a different molar ratio of Cu and Fe were prepared by co-precipitation method. Hydrogen production consisted of water-splitting step and thermal reduction step was performed below 1200K. Redox characteristics of Cu-ferrites were studied using the thermal gravimetric analysis technique. Also, structure change of Cu-ferrite during thermal reduction was investigated using the high temperature controlled XRD. In results, oxygen release of Cu-ferrite during the thermal reduction was initiated at oxygen site combined with Cu. Consequently, oxygen release amount of Cu-ferrite was increased with increase of Cu molar ratio of Cu-ferrite. It was found that thermal reduction of Cu-ferrite was begun at $875^\circ{C}$. It was confirmed that structure of Cu-ferrite was changed to metal and cation excess metal oxide during the thermal reduction step.

• Resources Recycling
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• v.13 no.1
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• pp.22-27
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• 2004

Purification on the leaching solution of the crude zinc oxide obtained by the reduction of EAF dust has been carried out. Pb and Cd ions in the leaching solution were precipitated and removed from the solution by the addition of zinc metal powder. The purification condition for electrowinning to obtain the high purity zinc metal was investigated by analyzing the effects of Pb and Cd ion concentrations on the contents of impurities in the recovered zinc metal. The 3 N purity zinc metal was obtained at the electrolysis condition of the concentrations of Pb less than 2 ppm and Cd less than 0.1 ppm in the purified solution. For this purification, the amounts of zinc metal powder more than 8.5 g/l should be added in the crude zinc oxide leached solution.

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.1
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• pp.143-179
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• 1989

To observe the bonding behavior of palladium-based alloys to porcelain; 1. Pd-Co binary alloy with the higher cobalt content, 2. Pd-Co binary alloy with the lower cobalt content, 3. Pd-Ag-Sn ternary alloy, 4. Pd-Ag binary alloy, 5. Pd-Cu-Au ternary alloy and 6. Pd-Cu binary alloy were made as 6 groups of experimental alloys. Each group of alloy was divided into 4 sub-groups such as one sub-group that was not degassed and three sub-groups that degassed for 5 minutes, 10 minutes and 15 minutes. On each specimen, weight changes after degassing, morphological changes of oxide layer by changing the degassing time, compositional changes at metal-ceramic interface and bond strength of metal-ceramic measured with planar shear test were observed and compared. The results of the present study allow the following conclusions to be drawn: 1. The alloy showing the greatest bond strength was Pd-Cu alloy without gold and bond strength was decreased by alloying gold to them. 2. Although Pd-Co alloy showed the most prominent oxidation behavior, bond strength of them to porcelain was not greatly high by the formation of porosities at metal-ceramic interfaces. 3. Likewise tin, cobalt formed the peaks on line profiles at metal-ceramic interface, however copper did not exhibit such peaks on line profiles. 4. Mainly, oxide layer on Pd-Co alloy was composed with cobalt, and for Pd-Co alloy with higher cobalt content the rise of bond strength was not significant by increased degassing time. 5. On Pd-Ag alloy not containing tin, during degassing for 15 minutes silver content was increased at metal-ceramic interface. 6. As an oxidized element, tin formed the oxide layers that widen their area by increasing the degassing time, while cobalt and copper showed the morphological changes of particle or crystal on oxide layer.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.19-32
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• 2010

Electrolytic reduction technology is essential for the purpose of adopting pyroprocessing into spent oxide fuel as an alternative option in a back-end fuel cycle. Spent fuel consists of various metal oxides, and each metal oxide releases an oxygen element depending on its chemical characteristic during the electrolytic reduction process. In the present work, an electrolytic reduction behavior was estimated for voloxidized spent fuel based on the assumption that each metal-oxygen system is independent and behaves as an ideal solid solution. The electrolytic reduction was considered as a combination of a Li recovery and chemical reactions between the metal oxides such as uranium oxide and the produced Li metal. The calculated result revealed that most of the metal oxides were reduced by the process. It was evaluated that a reduced fraction of lanthanide oxides increased with a decreasing $Li_2O$ concentration. However, most of the lanthanides were expected to be stable in their oxide forms. In addition, a semi-empirical model for describing $U_3O_8$ electrolytic reduction behavior was proposed by considering Li diffusion and a chemical reaction between $U_3O_8$ and Li. Experimental data was used to determine model parameters and, then, the model was applied to calculate the reduction yield with time and to estimate the required time for a 99.9% reduction.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.947-953
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• 2002

Two types of electronic nose were used for investigating the quality of dried lavers stored at 5, 15, and $30^{\circ}C$ RH of 32, 43, and 75%. The electronic nose is composed of metal oxide sensors, and GC is based on SAW sensor. Quality change in dried lavers was described in terms of the sensitivities $(R_{gas}/R_{air})$ of the sensors. Principal component analysis (PCA) was carried out using data obtained from six metal oxide sensors. The first principal component scores were correlated with quality changes of dried lavers. As storage time increased, the stored laver cluster separated from that of fresh lavers. A chromatogram was obtained from GC based on SAW sensor. Olfactory image, A $VaporPrint^{TM}$ image for pattern recognition, showed a significant difference between the stored and the fresh samples. Dried lavers during storage at $30^{\circ}C$ and 75% had bacterial counts of $5.7{\times}10^6\;CFU/g$ after 8 day. Increase of microbial count correlated with the response of electronic nose $(r^2=0.87)$. Whereas, color values showed no correlation.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.318-318
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• 2012

A graphene layer is most important materials in resent year to enhance the electrical properties of semiconductor device due to high mobility, flexibility, strong mechanical resistance and transparency[1,2]. The resistance switching memory with the graphene layer have been reported for next generation nonvolatile memory device[3,4]. Also, the graphene layer is able to improve the electrical properties of memory device because of the high mobility and current density. In this study, the resistance switching memory device with metal-oxide nano-particles embedded in polyimide layer on the graphene mono-layer were fabricated. At first, the graphene layer was deposited $SiO_2$/Si substrate by using chemical vapor deposition. Then, a biphenyl-tetracarboxylic dianhydride-phenylene diamine poly-amic-acid was spin coated on the deposited metal layer on the graphene mono-layer. Then the samples were cured at $400^{\circ}C$ for 1 hour in $N_2$ atmosphere after drying at $135^{\circ}C$ for 30 min through rapid thermal annealing. The deposition of aluminum layer with thickness of 200 nm was done by a thermal evaporator. The electrical properties of device were measured at room temperature using an HP4156a precision semiconductor parameter analyzer and an Agilent 81101A pulse generator. We will discuss the switching mechanism of memory device with metal-oxide nano-particles on the graphene mono-layer.