• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.176-183
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• 2011

The electrochemical characteristics from various particle sizes of $Ce_{0.9}Gd_{0.1}O_{2-{\delta}}$ (CGO91) in composite cathode comprised of the samarium-strontium doped layered perovskite ($SmBa_{0.5}Sr_{0.5}Co_2O_{5+{\delta}}$) and CGO91 have been investigated for possible application as a cathode material for an intermediate temperature-operating solid oxide fuel cell (IT-SOFC). The area specific resistances (ASRs) of composite cathodes with CGO91 having smaller particle size ($0.4\sim42{\mu}m$) and SBSCO of 1 : 1 ratio (50wt% SBSCO and 50 wt% CGO91, SBSCO: 50) give the lowest ASR of $0.10{\mu}cm^2$ at $600^{\circ}C$ and $0.013{\Omega}cm^2$ at $700^{\circ}C$. However, composite cathodes with having relatively bigger CGO91 particle size show the two times higher ASR results than those of SBSCO : 50. From the 10 times thermal cycles in SBSCO : 50, the ASRs of SBSCO : 50 increased from $0.0193{\Omega}cm^2$ to $0.094{\Omega}cm^2$ at $700^{\circ}C$, however, the ASR value was maintained after 7 times of thermal cycling.

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.169-176
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• 2013

Solid state lithium oxide compounds of layered structure, which has high stability of structure, are mainly used as the cathode materials in lithium-ion batteries (LIBs). Recently, the investigation of Solid Electrolyte Interphase (SEI) between active materials and electrolyte has been focusing to improve the performance of lithium-ion batteries. For the investigation of the SEI, the study of surface properties of cathode materials and anode materials is also required in advance. $LiNiO_2$ and $LiCoO_2$ are very similar layered structure of cathode active materials and representative solid state lithium oxide compounds in LIBs. Various experimental and theoretical studies have been doing for $LiCoO_2$. The theoretical investigation of $LiNiO_2$ is not sufficient, however, even if experimental studies of $LiNiO_2$ are enough. In this study, the surface energies of nine facets of $LiNiO_2$ crystal facets were calculated by Density Functional Theory. In XRD data of $LiNiO_2$, (003), (104), (101), et al. facets are main surfaces in order. However, the results of calculation are different with XRD data. Thus, both (104) and (101) facets, which are energetically stable and measured in XRD, are mainly exposed in the surface of $LiNiO_2$ and it is expected that intercalation and de-intercalation of Li-ion will be affected by them.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.79-87
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• 1997

Anti-reflective and anti-static double layered films were prepared on the VDT panel by sol-gel spin-coating method. Their electrical, opticla, and mechanical properties were investigated. The outer SiO2 film with low re-fractive index was coated over the inner ATO(Antimony-doped Tin Oxide)-SiO2 film which was prepared by mixing ATO sol with SiO2 at molar ratio of 68:32 to satisfy the interference condition of double layers. The heat treatment was conducted at 45$0^{\circ}C$ for 30 min where residual organics were completely removed. The sheet resistance of ATO single layer showed the minimum value of 6$\times$107$\Omega$/$\square$ at 3 mol% addition of Sb and that of SiO2/ATO-SiO2 increased slightly with increasing SiO2 mol% up to 30 mol%, and then increased steeply to the value of 3$\times$108$\Omega$/$\square$ at 32 mol%. The reflectance of double layered films was about 0.64% at the wavelength of 550nm and the transmittance increased about 3.20%. The hardness of double layered films was almost the same as that of uncoated VDT panel, 471.4kg.f/mm2.

• Membrane Journal
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• v.27 no.2
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• pp.167-181
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• 2017

Graphene-based materials have been considered as a promising membrane material, due to its easy processability and atomic thickness. In this study, we studied on gas permeation behavior in few-layered GO membranes prepared by spin-coating method. The GO membrane structures were varied by using different GO flake sizes and GO solutions at various pH levels. The GO membranes prepared small flake size show more permeable and selective gas separation properties than large one due to shortening tortuosity. Also gas transport behaviors of the GO membranes are sensitive to slit width for gas diffusion because the pore size of GO membranes ranged from molecular sieving to Knudsen diffusion area. In particular, due to the narrow pore size of GO membranes and highly $CO_2$-philic properties of GO nanosheets, few-layered GO membranes exhibit ultrafast and $CO_2$ selective character in comparison with other gas molecules, which lead to outstanding $CO_2$ capture properties such as $CO_2/H_2$, $CO_2/CH_4$, and $CO_2/N_2$. This unusual gas transport through multi-layered GO nanosheets can explain a unique transport mechanism followed by an adsorption-facilitated diffusion behavior (i.e., surface diffusion mechanism). These findings provide the great insights for designing $CO_2$-selective membrane materials and the practical guidelines for gas transports through slit-like pores and lamellar structures.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.6
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• pp.369-373
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• 2008

Special concern has been given to the elevated arsenic content in soils because of its high mobility and toxicity. Layered double hydroxide (LDH) which has a high anionic exchange capacity is another potential anion adsorbent for toxic anions such as arsenic, chromate and selenium etc. The uptake of arsenate from aqueous solutions by the calcined Mg-Al LDH has been investigated. The sorption capacity was about 530 mmol/kg. Sorption isotherm was defined as L-type in which arsenate was removed by LDH through anion uptake reaction. Arsenate sorption by the calcined Mg-Al LDH was occurred by reconstruction of LDH's framework. Competitive adsorption revealed that Mg-Al LDH had higher selectivity for arsenate than for sulfate. These results strongly suggest that calcined Mg-Al LDH has a promising potential for efficient removal of toxic metal oxides like arsenates from aqueous environments.

• Journal of the Korean Chemical Society
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• v.53 no.4
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• pp.476-480
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• 2009

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.182-182
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• 2011

태양전지용 TCO로 사용되는 ITO 박막의 고온에서의 전기적 특성을 향상시키기 위하여 고온 안정성을 가지는 GZO/ITO 박막을 증착 하였다. GZO/ITO 박막의 특성은 버퍼 층인 ITO의 두께 및 구조에 의해 영향을 받는 것을 알 수 있었다.

• International journal of advanced smart convergence
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• v.2 no.2
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• pp.16-18
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• 2013

In this paper, we develop a method to design a flexible thin film audio systems utilizing Polyvinylidene fluoride. The system we designed showed the properties of increased transparency and sound pressure levels. As an input terminal transparent oxide thin film is adopted. In order to provide dielectric insulation, a transparent insulating oxide thin film is coated to obtain double -layered structure. In the range of visible light, the output from the output of the system showed an increased and improved sound pressure level. The piezoelectric polymer film of polyvinylidene fluoride (PVDF) is used to produce mechanical vibration due to the applied electrical voltage signal. An analog electric voltage signal is transformed into sound waves in the audio system.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1988.11a
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• pp.35-48
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• 1988

상대 접촉하고 있는 물체에 미끄럼 운동이 가해질 경우 마찰에 의해 발생되는 거의 모든 에너지는 열로써 나타나게 된다. 이러한 마찰열은 주로 adhered junctions의 파괴 및 표면돌기(surface asperities)들의 소성 변형에 의한 열역할적 비가역 반응의 결과로 발생된다. 접촉부위의 발생열은 양 접촉제의 접촉면에 전달되어 접촉표면 온도의 급격한 증가를 초래하며 그 결과로 여러가지 surface phenomena, 즉 마찰, 마모, 산화(oxidation), 부식 및 구조적 열화(structural degradation) 금속학적 상변화등에 큰 영향을 미치게 된다. 딸서 볼 및 로울링 엘레먼트 베어링, 기어, 캠과 태핏, 브레이크 등 기계요소의 설계를 위한 주인자로서 근래에 들어 접촉표면의 온도가 주목받고 있다. 표면에 존재하는 layer로서는 금속표면에 응착시킨 coating layers, contaminant films, physisorbed 또는 chemisorbed films, oxide layers 또는 마찰열에 의해 형성되는 경도가 아주 높은 내마모층(hard wear-resistant layers) 등이 고려될수 있다. 낮은 열전도성을 가진 oxide film이 접촉 표면이 온도를 증가시킨다는 것이 Jaeger에 의해 지적되었으며 Ling과 Lai는 moving heat sjource가 가해지는 layered surface의 표면온도분포를 구하면서 substrate와 thermal property가 다른 layer가 존재하게 되면 그 두께가 아주 얇더라도 (1 마이크론 정도) 표면온도는 크게 변화됨을 보였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.93-96
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• 1996

We developed three dimensional Monte carlo ion implantation simulator which simulate distributions of impurities under the ion implantation on the tilted multi-layered layer. Our simulation reveals three dimensional shadow effect and sidewall scattering effect due to the geometrical shapes. For the evaluation of the developed three dimensional Monte carlo ion implantation simulator, calculations with 100,000 ions have been performed for the island and hole structures with a thin oxide of 100$\AA$ and nitride of 2000$\AA$. The simulation results showed that the distribution of ion decreases near the conner of the hole structure covered with a nitride layer and increases near the conner for the island structure open to oxide. Moreover, three dimensional distributions of ions were obtained with varying incident energy, tilt and rotation angle, mask depth and three-dimensional structure geometry.