• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.158-158
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• 2009

The electrophoretic deposition(EPD) technique with a wide range of novel applications in the processing of advanced ceramic materials and coatings, has recently gained increasing interest both in academic and industrial sector not only because of the high versatility of its use with different materials and their combinations but also because of its cost-effectiveness requiring simple apparatus. Compared to other advanced shaping techniques, the EPD process is very versatile since it can be modified easily for a specific application. For example, deposition can be made on flat, cylinderical or any other shaped substrate with only minor charge in electrode design and positioning[1]. The synthesis of the nano-sized Ce0.2Sm0.8O1.9(SDC)particles prepared by aurea based low temperature hydrothermal process was investigated in this study[2].When we made the SDC nanoparticles, changed the time of synthesis of the SDC. The SDC nanoparticles were characterized with field-emission scanning electron microscope(FESEM), energy dispersive X-ray analysis(EDX), and X-ray diffraction(XRD). And also we researched the results of our investigation on electrophoretic deposition(EPD) of the SDC particles from its suspension in acetone solution onto a non-conducting NiO-SDC substrate. In principle, it is possible to carry out electrophoretic deposition on non-conducting substrates. In this case, the EPD of SDC particles on a NiO-SDC substrate was made possible through the use of a adequately porous substrate. The continuous pores in the substrates, when saturated with the solvent, helped in establishing a "conductive path" between the electrode and the particles in suspension[3-4]. Deposition rate was found to increase its increasing deposition time and voltage. After annealing the samples $1400^{\circ}C$, we observed that deposited substrate.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.286-287
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• 2012

Reset-first resistive switching mechanism based on reduction reaction in HfO2-x with oxygen drift-diffusion was studied. we first report that the indirect evidence of local filamentary conductive path formation in bulk HfO2 film with local TiOx region at Ti top electrode formed during forming process and presence of anion-migration at interface between electrode and HfO2 during resistive switching through high resolution transmission electron microscopy (HRTEM), electron disperse x-ray (EDX), and electron energy loss spectroscopy (EELS) mapping. Based on forming process mechanism, we expected that redox reaction from Ti/HfO2 to TiOx/HfO2-x was responsible for an increase of initial current with increasing the post-annealing process. First-reset resistive switching in above $350^{\circ}C$ annealed Ti/HfO2 film was exhibited and the redox phenomenon from Ti/HfO2 to TiOx/HfO2-x was observed with high angle annular dark field (HAADF) - scanning transmission electron microscopy (STEM), EDX and x-ray photoelectron spectroscopy. Therefore, we demonstrated that the migration of oxygen ions at interface region under external electrical bias contributed to bipolar resistive switching behavior.

• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.502-509
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• 2005

Sexual reproduction plays an important role in the biology and epidemiology of oomycete plant pathogens such as the heterothallic species Phytophthora infestans. Recent worldwide dispersal of A2 mating type strains of P. infestans resulted in increased virulence, gene transfer, and genetic variation, creating new challenges for disease management. To develop a genetic assay for mating type identification in P. infestans, we used the Amplified Fragment Length Polymorphism (AFLP) technique. The primer combination E+AT/M+CTA detected a fragment specific to A1 mating type (Mat-A1) of P. infestans. This fragment was cloned and sequenced, and a pair of primers (INF-1, INF-2) were designed and used to differentiate P. infestans Mat-A1 from Mat-A2 strains. The Mat A1-specific fragment was detected using Southern blot analysis of PCR products amplified with primers INF-1 and INF-2 from genomic DNA of 14 P. infestans Mat-A1 strains, but not 13 P. infestans Mat-A2 strains or 8 other isolates representing several Phytophthora spp. Southern blot analysis of genomic DNAs of P. infestans isolates revealed a 1.6 kb restriction enzyme (EcoRI, BamHI, AvaI)-fragment only in Mat-A1 strains. The A1 mating type-specific primers amplified a unique band under stringent annealing temperatures of $63^{\circ}C-64^{\circ}C$, suggesting that this PCR assay could be developed into a useful method for mating type determination of P. infestans in field material.

• The Korean Journal of Ceramics
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• 제6권3호
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• pp.219-223
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• 2000

The ferroelectric SBT films were deposited on Pt/Ti/SiO$_2$/Si substrates by liquid injection metalorganic chemical vapor deposition (MOCVD) with single-mixture solution of Sr[Ta(OEt)$_5$(dmae)]$_2$and Bi(C$_6$ 6/H$_5$)$_3$. The Sr/Ta and Bi/Ta ratio in SBT films depended on deposition temperature and mol ratio of precursor in the single-mixture solution. At the substrate temperature of 40$0^{\circ}C$, Sr/Ta and Bi/Ta ratio were close to 0.4 and 1 at precursor mol ratio of 0.5~1.0, respectively. As-deposited film was amorphous. However, after annealing at 75$0^{\circ}C$ for 30 min in oxygen atmosphere, the diffraction patterns indicated polycrystalline SBT phase. The remanent polarization (Pr) and coercive field (Ec) of SBT film annealed at 75$0^{\circ}C$ were 4.7$\mu$C/$\textrm{cm}^2$ and 115.7kV/cm at an applied voltage of 5V, respectively. The SBT films annealed at 75$0^{\circ}C$ showed practically no polarization fatigue up to 10$^10$ switching cycles.

• 한국재료학회지
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• 제23권11호
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• pp.655-660
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• 2013

Photoelectrochemical cells have been used in photolysis of water to generate hydrogen as a clean energy source. A high efficiency electrode for photoelectrochemical cell systems was realized using a ZnO hierarchical nanostructure. A ZnO nanofiber mat structure was fabricated by electrospinning of Zn solution on the substrate, followed by oxidation; on this substrate, hydrothermal synthesis of ZnO nanorods on the ZnO nanofibers was carried out to form a ZnO hierarchical structure. The thickness of the nanofiber mat and the thermal annealing temperature were determined as the parameters for optimization. The morphology of the structures was examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The performance of the ZnO nanofiber mat and the potential of the ZnO hierarchical structures as photoelectrochemical cell electrodes were evaluated by measurement of the photoelectron conversion efficiencies under UV light. The highest photoconversion efficiency observed was 63 % with a ZnO hierarchical structure annealed at $400^{\circ}C$ in air. The morphology and the crystalline quality of the electrode materials greatly influenced the electrode performance. Therefore, the combination of the two fabrication methods, electrospinning and hydrothermal synthesis, was successfully applied to fabricate a high performance photoelectrochemical cell electrode.

• 한국재료학회지
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• 제24권3호
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• pp.145-151
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• 2014

Solution-based Sb-doped $SnO_2$ (ATO) transparent conductive oxides using a low-temperature process were fabricated by an electrospray technique followed by spin coating. We demonstrated their structural, chemical, morphological, electrical, and optical properties by means of X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, Hall effect measurement system, and UV-Vis spectrophotometry. In order to investigate optimum electrical and optical properties at low-temperature annealing, we systemically coated two layer, four layer, and six layers of ATO sol-solution using spin-coating on the electrosprayed ATO thin films. The resistivity and optical transmittance of the ATO thin films decreased as the thickness of ATO sol-layer increased. Then, the ATO thin films with two sol-layers exhibited superb figure of merit compared to the other samples. The performance improvement in a low temperature process ($300^{\circ}C$) can be explained by the effect of enhanced carrier concentration due to the improved densification of the ATO thin films causing the optimum sol-layer coating. Therefore, the solution-based ATO thin films prepared at $300^{\circ}C$C exhibited the superb electrical (${\sim}7.25{\times}10^{-3}{\Omega}{\cdot}cm$) and optical transmittance (~83.1 %) performances.

• 한국자기학회지
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• 제11권5호
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• pp.202-210
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• 2001

자연산화 $Al_2$O$_3$층이 형성된 하부형태 터널링 자기저항 다층박막이 기본진공도 $10^{-9}$ Torr을 유지하는 UHV 챔버내에서 이온빔 스퍼터링과 dc 마그네트론 스퍼터링 법으로 증착되었다. 제작된 스핀의존터널링 (SDT) 접합소자의 최대 터널링자기저항(TMR)와 최소 접합저항과 면적곱(R$_{j}$ A) 각각 16~17%와 50-60$\Omega$$\mu\textrm{m}$$^2$이었다. 자기장하에서 열처리한 SDT접합에 대한 TMR향상과 (R$_{j}$ A) 감소의 변화는 미미하였다. 접합면적이 81$\mu\textrm{m}$$^2$에서 47$\mu\textrm{m}$$^2$까지 접합크기가 작이짐에 따라 TMR이 증가하고 (R$_{j}$ A)이 감소하는 의존성이 관찰되었다. 이러한 현상을 하부층 단자의 판흐름 저항값 의존효과와 스핀채널효과로 설명하였다.

• Journal of Welding and Joining
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• 제32권2호
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• pp.29-36
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• 2014

Recently, in order to enhance the function and usefulness of products, cladding of dissimilar materials that maximizes the performance of the material is being widely used in all areas of industry as an important process. Clad steel plate, produced by cladding stainless steel plate, an anticorrosive material, on carbon steel plate, is being used to produce pressure vessels. Stainless steel plate has good corrosion resistance, and carbon steel plate has good rigidity and strength; clad steel can satisfy all of these qualities at once. This study aims to find the ${\delta}$-ferrite behavior, mechanical properties, structure change, integrity and reliability of clad steel weld on hot rolled steel plates. For this purpose, multi-layer welding, repair welding and post weld heat treatment were implemented according to welding procedure specifications (WPS). In order to observe the mechanical properties and toughness of clad steel weld zone, post weld heat treatment was carried out according to ASME Sec. VIII Div.1 UW-40 procedure for post weld heat treatment. With heat treatment at $625^{\circ}C$, the hold time was used as the process variable, increased by intervals that were doubled each time, from 80 to 1,280 min. The structure of weld part was typical cast structure; localized primary austenite areas appeared near central vermicular ferrite and fusion line. The heat affected zone showed rough austenite structure created by the weld heat input. Due to annealing effects of heat treatment, the mechanical properties (tensile strength, hardness, impact value) of the heat affected area tended to decrease. From the results of this study, it is possible to conclude the integrity of clad steel welds is not affected much in field welding, repair welding, multi-layer welding, post weld heat treatment, etc.

• 마이크로전자및패키징학회지
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• 제12권2호
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• pp.149-154
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• 2005

궁극적으로 게이트를 저저항 복합 실리사이드로 대체하는 가능성을 확인하기 위해 70 nm 두께의 폴리실리콘 위에 각 20nm의 Ni, Co를 열증착기로 적층순서를 달리하여 poly/Ni/Co, poly/Co/Ni구조를 만들었다. 쾌속열처리기를 이용하여 실리사이드화 열처리를 40초간 $700{\~}1100^{\circ}C$ 범위에서 실시하였다. 복합 실리사이드의 온도별 전기저항변화, 두께변화, 표면조도변화를 각각 사점전기저항측정기와 광발산주사전자현미경, 주사탐침현미경으로 확인하였다. 적층순서와 관계없이 폴리실리콘으로부터 제조된 복합실리사이드는 $800^{\circ}C$ 이상부터 급격한 고저항을 보이고, 두께도 급격히 얇아졌다. 두께의 감소는 기존의 단결정에서는 없던 현상으로 폴리실리콘의 두께가 한정된 경우 금속성분의 inversion 현상이 커서 폴리실리콘이 오히려 실리사이드 상부에 위치하여 제거되기 때문이라고 생각되었고 $1000^{\circ}C$ 이상에서는 실리사이드가 형성되지 못하였다. 이러한 결과는 나노급 두께의 게이트를 저저항 실리사이드로 만 들기 위해서는 inversion과 두께감소를 고려하여야 함을 의미하였다.

• 한국결정성장학회지
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• 제16권6호
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• pp.244-249
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• 2006

본 연구에서는 새로운 나노 분말 제조방법 중의 하나인 정전분무 열분해법을 이용하여 칼슘 포스페이트 나노분말을 제조하였다. 정전 분무된 분말은 공기 중에서 $400^{\circ}C$로 30분간 열처리하여 고상화하였다. 결정화된 분말의 하이드록시 아파타이트 형성능력을 평가하기 위하여 Eagle's minimum essential medium solution(MEM)을 사용하였으며, MEM 용액에 침전된 후의 분말의 특성평가를 위하여 X-선 회절 분석법, 전계 방사 주사형 전자 현미경, 에너지 분산 X-선 분광계 및 퓨리에 변환 적외선 분광계를 사용하여 분석을 행하였다. 비정질 구조를 가진 나노 분말은 MEM 용액에 15일 침전 후, 분말의 표면에 유도된 하이드록시 아파타이트 결정을 확인할 수 있었다.