• 대한토목학회논문집
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• 제28권1B호
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• pp.149-152
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• 2008

철의 환원 특성에 관한 연구는 이미 널리 수행되었으며 특히 미네랄과 2가철의 반응 메커니즘은 2가철의 흡착이나 바운드를 통해 Fe(II)-Fe(III) (hydr)oxides를 생성하여 2가철이 3가철로 산화됨으로써 물질을 환원시키는 것으로 받아들여지고 있다. 그러나 2가철로 개질된 재강슬래그를 이용한 DS/S 실험과정에서 이러한 메커니즘으로 설명하기 힘든 현상을 발견하였다. 재강슬래그의 주요 성분중의 하나인 FeO와 Fe(II)만을 이용하여 TCE의 분해과정을 실험해 본 결과 초기 TCE의 분해가 이루어지지 않다가 급속히 분해되는 현상을 보였으며 이러한 시스템에서 TCE의 분해는 예상치 못한 결과였다. FeO/Fe(II) 시스템은 3가철이 존재하지 않기 때문에 기존의 Fe(II)-Fe(III) (hydr)oxides를 형성하는 환원 메커니즘으로는 설명할 수 없었다. 따라서 본 연구에서는 TCE의 분해실험과 분해 부산물의 측정, 2가철과 3가철을 확인함으로써 FeO/Fe(II) 시스템의 환원특성을 확인해 보고자 하였다. 실험 결과 2가철이 FeO에 흡착 또는 바운드 되는 것을 확인 할 수 는 있었으나 기존의 메커니즘으로 설명하기에는 부족한 부분이 있었다. 분해부산물들을 통해 환원으로 인한 TCE의 분해는 의심의 여지가 없었으나 FeO/Fe(II) 시스템이 새로운 species를 형성하는지, 혹은 FeO에 Fe(II)가 흡착 또는 바운드 되어 이제껏 알려지지 않은 형태의 새로운 미네랄 상을 형성하는지는 좀 더 상세한 연구가 필요하다.

• Applied Microscopy
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• 제45권4호
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• pp.236-241
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• 2015

Carbon-coated Ni, Cu and Sn nanocapsules were investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and a four-point probe device. All of these nanocapsules were prepared by an arc-discharge method, in which the bulk metals were evaporated under methane ($CH_4$) atmosphere. Three pure metals (Ni, Cu, Sn) were typically diverse in formation of the carbon encapsulated nanoparticles and their different mechanisms were investigated. It was indicated that a thick carbon layers formed on the surface of Ni(C) nanocapsules, whereas a thin shell of carbon with 1~2 layers covered on Cu(C) nanocapsules, and the Sn(C) nanocapsules was, in fact, a longger multi-walled carbon nanotubes partially-filled with metal Sn. As one typical magnetic/dielectric nanocomposite particles, Ni(C) nanocapsules and its counterpart of oxide-coated Ni(O) nanocapsules were compared in the electrically conductive behaviors for further applications as the electromagnetic materials.

• Nuclear Engineering and Technology
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• 제23권4호
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• pp.438-443
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• 1991

각확산도가 작은 $He^+$ 이온빔 인출전류를 최대로 얻기 위하여 Duoplasmatron 이온원의 동작특성을 조사하였다. 이온원의 기체압력, 아크전류. 전자석 전류, 인출전압등을 변화시키면서 인출되는 $He^+$ 이온빔 전류의 변화를 관찰하였다. 열음극으로는 Ni망위에 BaO와 SrO의 혼합물을 코팅한 산화물 필라멘트를 사용하였으며, 그것의 평균수명은 약 100시간이었다. 인출전류는 아크전류에 선형적으로 비례했다 이온원 전자석전류를 증가시킴에 따라 인출전류는 증가하였지만 빔의 각확산도가 커졌다. 최대의 인출전류는 0.084 Torr의 이온원 압력에서 얻어졌다. 인출전류는 이론에서와 마찬가지로 인출전압의 3/2승에 비례하였다. 5.72 kV의 인출전압에서는 최적인출조건하에서 50 $\mu$A의 인출전류가 얻어졌다.

• 한국재료학회지
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• 제12권9호
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• pp.712-717
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• 2002

New wet chemical method so called precipitation-evaporation method was suggested for preparing spinel structure lithium manganese oxide ($LiMn_2$$O_4$) for Li ion secondary battery. Using precipitation-evaporation method, $LiMn_2$$O_4$ cathode materials suitable for Li ion secondary batteries can be synthesized. Single spinel phase $LiMn_2$$O_4$ powder was synthesized at lower temperature compared to that of prepared by solid-state method. $LiMn_2$$O_4$ powder prepared by precipitation-evaporation method showed uniform, small size and well defined crystallinity particles. Li ion secondary battery using $LiMn_2$$O_4$ as cathode materials prepared by precipitation-evaporation method and calcined at $800^{\circ}C$ showed discharge capacity of 106.03mAh/g and discharge capacity of 95.60mAh/g at 10th cycle. Although Li ion secondary battery showed somewhat smaller initial capacity but good cyclic ability. It is suggested that electro-chemical properties can be improved by controlling particle characteristics by particle morphology modification during calcination and optimizing Li ion secondary battery assembly conditions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.300-300
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• 2008

In this study, the advanced DuoPIGatron-type ion beam (IB) system was applied to inorganic thin film for aligning liquid crystal (LC). LC alignment on $Ta_2O_5$ via IB irradiation was embodied. As a result of IB irradiation, the homogeneously aligned liquid crystal display (LCD) on $Ta_2O_5$ was observed with low pretilt angles. The $Ta_2O_5$ were deposited on indium-tin-oxide coated Coming 1737 glass substrates by rf magnetron sputtering at $200^{\circ}C$. The deposition process resulted in forming very uniform thin film on glass substrates without any defects. To confirm the application of the inorganic alignment on modem display optical devices, we fabricated twisted nematic LCD and measured optical property and response time. As a result of the experiment, the electro optical characteristics of the LCD fabricated by using IB irradiation on $Ta_2O_5$ alignment layer were similar with the other LCD fabricated by using rubbing process.

• 전기화학회지
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• 제11권4호
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• pp.242-255
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• 2008

1991년 lithium-ion battery(LIB)가 상용화된 이후, 초기 전해질은 주로 lithium cobalt oxide($LiCoO_2$) 양극과 graphite 음극의 특성에 집중되어 연구되어 왔다. 또한 전극과 전해질 간의 적합성에 대한 다양한 연구들이 이들 간의 계면에서 활발히 진행되었다. 이후 Si, Sn 등의 비탄소계 음극소재와 3성분(Ni, Mn, Co)계, spinel, olivine 등의 양극 소재를 리튬 2차전지에 채용하려 함에 따라 기존 전해질 재료들도 많은 도전에 직면하게 되었다. 특히, 안전성 문제가 최근 심각하게 부각됨에 따라 전해질의 요구특성은 점점 복잡해지고 까다로워지고 있다. 본 고에서는 이러한 전극소재 변화에 따른 전해질 소재의 다양한 변화와 그 특성에 대하여 구성요소 별로 연구 및 개발 동향을 정리하였다.

• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.352-360
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• 2020

Lithium cobalt oxide (LiCoO₂, LCO) has been widely used as a cathode material for Li-ion batteries (LIBs) owing to its excellent electrochemical performance and highly reproducible synthesis even with mass production. To improve the energy density of the LIBs for their deployment in electro-mobility, the full capacity and voltage of the cathode materials need to exploited, especially by operating them at a higher voltage. Herein, we doped LCO with divalent calcium-ion (Ca²⁺) to stabilize its layered structure during the batteries' operation. The Ca-doped LCO was synthesized by two different routes, namely solid-state and co-precipitation methods, which led to different average particle sizes and levels of dopant's homogeneity. Of these two, the solid-state synthesis resulted in smaller particles with a better homogeneity of the dopant, which led to better electrochemical performance, specifically when operated at a high voltage of 4.5 V. Electrochemical simulations based on a single particle model provided theoretical corroboration for the positive effects of the reduced particle size on the higher rate capability.

• The Journal of Advanced Prosthodontics
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• 제6권3호
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• pp.157-164
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• 2014

PURPOSE. This study focused on in vitro cell differentiation and surface characteristics in a magnesium coated titanium surface implanted on using a plasma ion source. MATERIALS AND METHODS. 40 commercially made pure titanium discs were prepared to produce Ti oxide machined surface (M) and Mg-incorporated Ti oxide machined surface (MM). Surface properties were analyzed using a scanning electron microscopy (SEM). On each surface, alkaline phosphatase (ALP) activity, alizarin red S staining for mineralization of MC3T3-E1 cells, and quantitative analysis of osteoblastic gene expression, were evaluated. Actin ring formation assay and gene expression analysis of TRAP and GAPDH performing RT-PCR were performed to characterize osteoclast differentiation on mouse bone marrow-derived macrophages (BMMs). RESULTS. MM showed similar surface morphology and surface roughness with M, but was slightly smoother after ion implantation at the micron scale. M was more hydrophobic than MM. No significant difference between surfaces on ALP activity at 7 and 14 days were observed. Real-time PCR analyses showed similar levels of mRNA expression of the osteoblast phenotype genes; osteopontin (OPN), osteocalcin (OCN), bone sialoprotein (BSP), and collagen 1 (Col 1) in cell grown on MM at 7, 14 and 21 days. Alizarin red S staining at 21 days showed no significant difference. BMMs differentiation increased in M and MM. Actin ring formation assay and gene expression analysis of TRAP showed osteoclast differentiation to be more active on MM. CONCLUSION. Both M and MM have a good effect on osteoblastic cell differentiation, but MM may speed the bone remodeling process by activating on osteoclast differentiation.

• 한국세라믹학회지
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• 제40권11호
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• pp.1085-1089
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• 2003

본 연구에서는 리튬이차전지의 음극재료로서 사용되고 있는 Mesocarbon Microbeads (MCMB) 카본 분말에 제2상 첨가물로서 소량의 주석산화물 (SnO$_2$) 을 균일하게 분산 첨가시킴으로써 카본전극 표면을 개질시켰으며, 이에 따른 전극의 전기화학적 특성 변화에 관하여 고찰하였다. 주석산화물 첨가 방법는 전하적정법을 사용하여 Sn 을 MCMB 분말에 삽입시키고, 다시 삽입된 Sn이 산화되도록 대기 중에서 25$0^{\circ}C$로 l 시간동안 후열처리를 하였다. 주석산화물이 첨가된 MCMB 카본분말로 Li/MCMB 전지 cell을 만들어 충방전시험을 수행한 결과, raw MCMB로 만든 전극보다 더 우수한 충방전 용량과 싸이클 특성을 나타내었다. 즉, 주석산화물 삽입에 의해 표면개질된 MCMB 카본 분말은 기존의 MCMB에 비해 높은 초기 방전용량과 충전용량을 나타내었고, 또한 높은 가역특성과 좋은 cycleability를 보였다. 삽입된 SnO$_2$의 양이 증가할수록 높은 가역용량을 나타내었고 비가역용량 역시 높은 값을 나타내었다.

• 한국전기전자재료학회논문지
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• 제28권5호
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• pp.295-299
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• 2015

In this paper to improve the ionic conduction properties, lanthanum silicate apatite $La_{9.33}(SiO_4)_6O_2$ ceramic, which substituted by V ions at Si-site, were fabricated by the mixed-oxide method. And we investigated the structural and electrical properties of $La_{9.33}(Si_{6-x}V_x)O_{26}$ specimens with variation of dopants for the application of solid oxide fuel cells. The sintering temperature of $La_{9.33}(Si_{6-x}V_x)O_{26}$ specimens decreased from $1,600^{\circ}C$ to $1,400^{\circ}C$. As results of X-ray diffraction patterns, all $La_{9.33}(Si_{6-x}V_x)O_{26}$ specimens showed the formation of a complete solid solution in a apatite polycrystallin structure. But the specimens doped with more than 1.5mol% showed the second phase, $La_2SiO_5$ and $SiO_2$. The specimen dopants with 1.0 mol% showed the maximum ion conductivity. Ion conducting and activation energy of the $La_{9.33}(Si_5V_1)O_26$ specimens were about $7.8{\times}10^{-4}S/cm$ 1.62 eV at $600^{\circ}C$, respectively.