• Journal of the Korean Ceramic Society
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• v.38 no.3
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• pp.274-279
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• 2001

Pt/Ti/Si 기판 위에 성장시킨 박막 전지용 비정질 산화 바나듐 박막에 고상 전해질 박막 LiPON을 이용하여 전고상형 박막전지를 제작하여 충-방전 시험을 시행하였다. 이렇게 제작된 전고상형 박막전지는 500 사이클 이상까지 평균 15$\mu$Ah의 방전용량을 나타내었으나 초기 사이클 영역부터 방전 용량의 감소가 일어나기 시작했다. 박막 전지의 방전 용량 감소에 따른 비정질 산화 바나듐 박막의 구조적 특성 변화를 관찰하기 위하여 고분해능 현미경 분석을 시행하였다. 충-방전을 하지 않은 초기의 산화 바나듐 박막은 입계를 갖지 않고 다결정 특성을 보이지 않는 완전한 비정질 특성을 보였고 이는 TED 결과와 일치하였다. 그러나 450번의 반복적인 충-방전을 시행한 후의 비정질 산화 바나듐 박막 내에는 microcrystalline 형태의 산화 바나듐의 형성됨을 고분해능 전자 현미경 분석을 통해 발견할 수 있었다. 비정질 산화바나듐 박막의 방전 용량 감소의 원인인 Li의 비가역적 탈-삽입은 비정질 내에 형성된 microcrystalline에 의해 유발된다고 사료된다. 또한 LiPON 전해질 박막과 산화 바나듐 박막사이의 계면에 Li 이온과 산화바나듐과의 반응에 의해 형성된 계면 층에 발견할 수 있었는데 이러한 계면 층 역시 Li 확산과 계면 저항에 영향을 주어 방전 용량 감소에 원인으로 작용한다.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.1
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• pp.58-67
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• 1992

For removing $NO_x$ and $SO_x$ from the flue gases emitted from stationary sources, $V_2O_5-MoO_3/TiO_2$ catalysts were prepared by the conventional impregnation method (aqueous solution) and a sort of surface fixation method(nonaqueous solution) as reported excellent reproducibility catalysts. And these catalysts observed their catalytic activities as well as their surface properties. V-Mo-O oxide, prepared from nonaqueous solution of $VOCl_3$ and $Mo(CO)_6$ and aqeous solution method, was supported as amorphous state by XRD and SEM measurements. The infrared spectra of fresh and used catalysts showed that in used catalysts, V=O bands decreased and new bands of vanadium oxysulfate bands were very sensitive. So the catalysts prepared from nonaqueous solution may bring about the high activity. Results from catalytic activity measurements at 350$^\circ$C, in the presence of $SO_2, NO$ conversion was more increased than in absence of $SO_2$. As the $MoO_3$ was added to $V_2O_5/TiO_2 system, SO_2$ conversion increased. It found that from the results, $V_2O-5-MoO_3/TiO_2$ catalysts prepared from an nonaqueous solution may bring about the high activity for both the reaction of NO and $SO_2$ removal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.237-238
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• 2008

The films of Vanadium tungsten oxide, $V_{1.85}W_{0.15}O_5$, were grown on Pt/Ti/$SiO_2$/Si substrate by RF sputtering method. The $V_{1.85}W_{0.15}O_5$ thin films deposited on Pt/Ti/$SiO_2$/Si substrates by RF sputtering method exhibited fairly good TCR and dielectric properties. It was found that film crystallinity, dielectric properties, and TCR properties were strongly dependent upon the annealing temperature. The dielectric constants of the $V_{1.85}W_{0.15}O_5$ thin films annealed at $300^{\circ}C$ were 55, with a dielectric loss of 1.435, respectively. Also, the TCR values of the $V_{1.85}W_{0.15}O_5$ thin films annealed at $300^{\circ}C$ were about -3.6%/K.

• Journal of the Korean Ceramic Society
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• v.47 no.4
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• pp.302-307
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• 2010

This study aims to synthesize emerald-green malayaite pigments using $CaCO_3$, $SiO_2$, $SnO_2$ and $V_2O_5$. For this purpose, the optimum composition is $CaV_{0.25}Sn_{0.687}SiO_5$ and heating condition is at $1250^{\circ}C$ for 6 h of soaking time. The samples were characterized by X-ray diffraction (XRD), the Fourier Transform Infrared Spectrometers(FT-IR), the Raman Spectrometer, Scanning Electron Microscope(SEM) and the UV/Vis spectroscopy. The substituted V ion for Sn was observed to be quadrivalence. The analytical results of the synthesized pigment showed the tetragonal crystal, a typical form of Malayaite, and the particle size to be approximately $5{\sim}10\;{\mu}m$. The color in lime glaze added 12 wt% pigment was emerald green, and CIE Lab parameters are $L^*=67.73$, $a^*=-12.39$ and $b^*=9.28$.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.133-133
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• 2011

최근 나노입자를 이용한 비휘발성 메모리 소자의 제작에 대한 연구가 진행되고 있다. 특히, 실리사이드 계열의 나노입자를 적용한 소자는 일함수가 크지만 실리콘 내의확산 문제를 가지고 있는 금속 나노입자와 달리 현 실리콘 기반의 반도체 공정 적용이 용이한 잇 점을 가지고 있다. 따라서 본 연구에서는 실리사이드 계열의 화합물 중에서 4.63 eV인 Vanadium Silicide ($V_3$Si) 박막을 열처리 과정을 통하여 수 nm 크기의 나노입자로 제작하였다. 소자의 제작은 p-Si기판에 5 nm 두께의 $SiO_2$ 터널층을 dry oxidation 방법으로 성장시킨 후 $V_3$Si 금속박막을 RF magnetron sputtering system을 이용하여 3~5 nm 두께로 tunnel barrier위에 증착시켰다. Rapid thermal annealing법으로 질소 분위기에서 $1000^{\circ}C$의 온도로 30초 동안 열처리하여 $V_3$Si 나노 입자를 형성 하였으며. 20 nm 두께의 $SiO_2$ 컨트롤 산화막층을 ultra-high vacuum magnetron sputtering을 이용하여 증착하였다. 마지막으로 thermal evaporation system을 통하여 Al 전극을 직경 200, 두께 200nm로 증착하였다. 제작된 구조는 metal-oxide-semiconductor구조를 가지는 나노 부유 게이트 커패시터 이며, 제작된 시편은 transmission electron microscopy을 이용하여 $V_3$Si 나노입자의 크기와 균일성을 확인했다. 소자의 전기적인 측정은 E4980A capacitor parameter analyzer와 Agilent 81104A apulse pattern generator system을 이용한 전기용량-전압 측정을 통해 전하저장 효과를 분석하였다.

• Journal of Powder Materials
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• v.1 no.2
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• pp.153-158
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• 1994

The effect of the role of alloyed components on the densification of two kind of high speed steel (mixed and prealloyed powder), which were sintered at 1403~ 1573 K for 7.2 ks in vacuum, was investigated. The results obtained were as follows. (1) Without the presence of Vanadium (V), the relative density of sintered compacts (Ds) could not reached the density of 100% regardless of the. elements in the compacts. (2) The addition of V up to 2 mass% did not result In the complete densification when the carbon content was fixed at 2% in the compact. (3) With the fixed amount of V of 7%, Ds decreased with the increase of the carbon content. (4) The addition of mixed fine powder to the prealloyed powder in the range of 20 to 40% provided the complete densification and carbide panicles of 1~2 $\mu\textrm{m}$ through the solid phase sintering. (5) The V element played important role in controlling the complete or incomplete densification of the sintered compacts in the alloyed component because of its formation of stable oxide and carbide as well as the low equilibrium pressure of CO gas.

• Transactions on Electrical and Electronic Materials
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• v.16 no.4
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• pp.221-225
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• 2015

The sintering effect on the microstructure, electrical properties, and dielectric characteristics of ZnO-V₂O₅-MnO₂-Nb₂O₅-Dy₂O₃-based ceramics was investigated. With the increase of sintering temperature from 875 to 950℃, the density of the sintered pellets decreased from 5.57 to 5.45 g/cm³ and the average grain size increased from 4.3 to 10.9 μm. The breakdown field decreased noticeably from 6,095 to 996 V/cm with the increase of sintering temperature. The varistor ceramics sintered at 900℃ exhibited the best nonlinear properties: 39.2 in the nonlinear coefficient and 0.24 mA/cm² in the leakage current density. The dielectric constant increased sharply from 658.6 to 2,928.8 with the increase of sintering temperature. On the whole, the dissipation factor exhibited a fluctuation with the increase of the sintering temperature, and a minimum value of 0.284 at 900℃.

• Nuclear Engineering and Technology
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• v.40 no.2
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• pp.99-106
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• 2008

Through mechanical alloying, hot isostatic pressing and hot rolling, a 9%Cr Fe-based oxide dispersion-strengthened alloy sample was fabricated. The tensile strength of the alloy is significantly improved when the microstructure is modified during the post-consolidation process. The alloy samples were strengthened as the cooling rates increased, though the elongation was somewhat reduced. With a cooling rate of $800^{\circ}C/s$ after normalization at $1150^{\circ}C$, the alloy sample showed a tensile strength of 1450 MPa, which is about twice that of the hot rolled sample; however, at $600^{\circ}C$ the tensile strength dramatically decreased to 620 MPa. Optical microscope and transmission electron microscope were used to investigate the microstructural changes of the specimens. The resultant strengthening of the alloy sample could be mainly attributed to the interstitially dissolved nitrogen, the fraction of the tempered martensite, the fine grain and the presence of a smaller precipitate. The decrease in the tensile strength was mainly caused by the precipitation of vanadium-rich nitride.

• Journal of Powder Materials
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• v.28 no.5
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• pp.417-422
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• 2021

In the present work, Inconel 718 alloy is additively manufactured on the Ti-6Al-4V alloy, and a functionally graded material is built between Inconel 718 and Ti-6Al-4V alloys. The vanadium interlayer is applied to prevent the formation of detrimental intermetallic compounds between Ti-6Al-4V and Inconel 718 by direct joining. The additive manufacturing of Inconel 718 alloy is performed by changing the laser power and scan speed. The microstructures of the joint interface are characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and micro X-ray diffraction. Additive manufacturing is successfully performed by changing the energy input. The micro Vickers hardness of the additive manufactured Inconel 718 dramatically increased owing to the presence of the Cr-oxide phase, which is formed by the difference in energy input.

• Particle and aerosol research
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• v.16 no.4
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• pp.95-105
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• 2020

Vanadium Pentoxide (V2O5) has been emerged as alternative electrode materials for supercapacitors due to their low cost, natural abundance, and environmental friendliness. Graphene (GR) loaded with V2O5 can exhibit enhanced specific capacitance. In this study, we present three-dimensional (3D) crumpled graphene (CGR) decorated with V2O5. The V2O5-graphene composites were synthesized from a colloidal mixture of graphene oxide (GO) and Ammonium metavanadate (NH4VO3), via aerosol spray drying and post heat treatment process. The average size of composite was ranged from 1.82 to 4.6 ㎛. Morphology of the composite changed from a crumpled paper ball to spherical ball having relatively smooth surface as the content of V2O5 increased in the composites. The electrochemical performance of the V2O5-graphene composites was examined. The V2O5-graphene composite electrode showed the specific capacitance of 312 F/g. In addition, the device possessed acceptable cyclic stability, with 84% after 2000 cycles at 2 A/g. These outstanding properties are expected to make the composites prepared in this study as promising electrode materials for supercapacitor applications.