• Journal of Adhesion and Interface
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• v.16 no.3
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• pp.116-121
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• 2015

In this study, octadecyltrichlorosilane (OTS) has been used to replace fluoro-silanes which are much more expensive than OTS. In order to improve the mechanical and adhesive properties of coating layers, inorganic binders were separately synthesized based on sol-gel reaction in acidic condition. Since the synthesized silica nanoparticles gave only nano-scaled roughness, superhydrophobicity is not well obtained. Here, we present a new simple approach by intentionally inducing particle aggregation in the solution which is controlled by adjusting solvent amount. With selecting suitable sizes of silica nanoparticles, superhydrophobic surfaces were obtained with increasing the amount of organic solvents after surface hydrophobization using OTS, and an extremely water-repellent behavior was observed with zero sliding angle. This superhydrophobicity was achived only for the dielectric constant lower than 25, regardless of the composition of solvent, meaning that the dielectric constant could be an excellent indicator for fabricating superhydrobic surfaces induced by particle aggregation in the solution.

• Membrane Journal
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• v.20 no.1
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• pp.21-28
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• 2010

Organic/inorganic composite electrolyte membranes were prepared for dye sensitized solar cell (DSSC). Poly (ethylene glycol) (PEG)s with various molecular weight (600, 1,500, 2,000 and 3,400) were ethoxysilated to fabricate organic/inorganic composite materials through sol-gel processes. The electrolyte membranes were produced by doping the composite materials with KI and $I_2$, and their ionic conducting behaviors were investigated. The ionic conductivity of the composite membrane was highly affected by PEG molecular weight. The highest conductivity was shown by the composite membrane prepared with PEG with the molecular weight of 2,000. The composite electrolyte membranes showed considerable improvement of ionic conductivity. Compared to PEO electrolyte membranes, the composite electrolyte membrane by PEG, MW 2,000 showed much higher ionic conductivity.

• Korean Journal of Materials Research
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• v.10 no.5
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• pp.360-363
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• 2000

Deformation in the hysteresis loop of $Pb(Zr,Ti)O_3$ (PZT) thin films with various Zr/Ti ratios has been studied by varying the top electrode preparation method and the annealing temperature. Pt/PZT/Pt capacitors was found to be positively poled due to dc plasma potential generated during reactive ion etch (RIE) of Rt. Internal field is formed by space charges trapped at domain boundaries. Aging phenomenon such as constriction in the middle of the hysteresis loop was observed in the PZT film with top electrode deposited by sputtering. Top electrode annealing restores the hysteresis loop by removing the space charges. As Zr/Ti ratio decrease, voltage shift increases and an-nealing temperature at which internal field disappears also increases.

• Membrane Journal
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• v.18 no.4
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• pp.345-353
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• 2008

Organic/inorganic composite electrolyte membranes were prepared for dye sensitized solar cell (DSSC). Polyethylene Glycol (PEG)s with various molecular weight (400, 600, 1,500 and 3,400) was ethoxysilated to fabricate organic/inorganic composite materials through sol-gel processes. The electrolyte membranes were produced by doping the composite materials with NaI and $I_2$, and their ionic conducting behavior was investigated. The ionic conductivity of the composite electrolyte was highly affected by the PEG molecular weight, and the highest conductivity was shown by the composite membrane prepared with PEG with the molecular weight of 1,500. The composite electrolyte membranes showed considerable improvement of ionic conductivity. Compared to PEO electrolyte membranes, the composite electrolyte membrane prepared by PEG, MW 1,500, showed much higher ionic conductivity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.5
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• pp.565-569
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• 1993

Antioxidative activity of browning product(BP) fractionated from fermented soybean sauce(SS) was studied during the oxidation process of linoleic acid mixture system. SSBP was a powder type product prepared from fermented soybean sauce by the fractionation through the Sephadex G-10 column and freeze drying of collected fraction. The aqueous model systems were used for the evaluation of antioxidative activity of SSBP during the oxidative reaction at $50^{\circ}C$ by the determination of peroxider and conjugated dienoic acid compounds. The linoleic acid mixture for the aqueous model systems was consisted of linoleic acid(64.6%), oleic acid(27.4%), and other acids in ethanolic phosphate buffer solution(pH 7.0). SSBP had a considerable antioxidative activity with the inhibition of formation of peroxides and conjugated dienoic acids during the autoxidation of linoleic acid mixtures in aqueous model systems. Antioxidative activity of SSBP was relatively higher than SS, however, lower than ${\alpha}-tocopherol$ and butylated hydroxyanisol. The antioxidative effect of SSBP was increased by the its concentrations from 0.05% to 0.5% in the oxidation reactions of aqueous model systems. Therefore, SSBP was considered as one of the potential natural antioxidants for the use of food products.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.97-97
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• 2011

산화아연 (ZnO)은 넓은 에너지 밴드갭 (~3.37 eV), 큰 엑시톤 결합 에너지 (~60 meV) 그리고 높은 전자 이동도 (bulk~300 $cm^2Vs^{-1}$, single nanowire~1000 $cm^2Vs^{-1}$)를 갖고 있어, 광전자 소자 및 반도체소자 응용에 매우 널리 사용되고 있다. 특히, 산화아연 나노로드(ZnO nanorod)는 1차원 나노구조로써 더욱 향상된 전자 이동도와 캐리어의 direct path way를 제공하여 차세대 광전자소자 및 태양광 소자의 응용에 대한 연구가 매우 활발하게 이루어지고 있다. 한편, 이러한 산화아연 나노로드를 성장시키기 위하여 VLS (vapor-liquid-solid), 졸-겔 공정(sol-gel process), 수열합성(hydrothermal synthesis), 전기증착(electrodeposition)등 다양한 방법이 보고되었지만, 이러한 산화아연 나노로드의 성장방법은 실제적인 소자응용을 위한 패터닝 형성에 대하여 제약을 받는 문제점이 있다. 이들 중에서 수열합성법과 전극증착법은 ZnO 또는 AZO (Al doped ZnO) seed 층 표면과 성장용액의 화학반응에 의해서 선택적으로 산화아연 나노로드를 성장시킬 수 있다. 이에 본 연구에서는, 광전자소자의 응용을 위한 간단한 패터닝 공정을 위해, 산화인듐주석(ITO) 박막이 증착된 유리기판(glass substrate)위에 수열합성법과 전극증착법을 이용하여 산화아연 나노로드를 선택적으로 성장시켰다. 실험을 위해, ITO glass 위에 RF magnetron 스퍼터를 사용하여 AZO seed 층을 metal shadow mask를 이용하여 패터닝을 형성한 후, 질산아연과 헥사메틸렌테트라아민으로 혼합된 용액에 $85^{\circ}C$ 온도를 유지하여, 패터닝이 형성된 샘플에 전압을 인가하여 성장시켰다. 나노구조 분석을 위해, 전계주사현미경을 이용하여 수열합성법과 전기증착법에 의한 패터닝된 산화아연 나노로드를 비교하여 관찰하였다.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.369-374
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• 2008

This study is an inorganic foaming ceramic by sol-gel reaction in order to overcome weak point of insulator using in construction equipment. We shall be able to confirm as the existing product substitute is possible result of this study. The solution where the silicate, the ceramic powder and the additive are included which makes foaming ceramic slurry, then the insulator made by used $CO_2$ Sol-Gel reaction. There being will be able to manufacture the insulator where the economical efficiency is excellent confirmed at the start product which is completed. The recording gel time decreases when the silicate will increase. Uses the hydrogen peroxide and fe make foam, when additionally surface preparation the fluorine resin, the water tolerance increases and will be able to complement the weak point of the silicate which omits in the water. The case which will use the loess powder with the research method which sees specially was environment-friendly product and according to appearing, the physical properties of nonflammability.

• Elastomers and Composites
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• v.44 no.3
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• pp.290-298
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• 2009

In this paper, the Fe-activated carbon fiber (ACF)/$TiO_2$ composite catalysts were prepared by a sol-gel method. The synthesized photocatalysts were used for the photo degradation of Methylene blue solution under UV light. From Brunauer-Emmett-Teller measurements (BET) data, it was shown the blocking of the micropores on the surface of ACF by treatment of Fe and Ti compound. As shown in SEM images, the ferric compounds and titanium dioxides were fixed onto the ACF surfaces. The result of X-ray powder diffraction showed that the crystal phase contained a mixing anatase and rutile structure and the 'FeO+$TiO_2$' from the composites. The EDX spectra for the elemental analysis showed the presence of C, O, and Ti with Fe peaks. Degradation activity of MB could be attributed to +OH radicals derived from electron/hole pair's reactions due to photolysis of $TiO_2$ and photo-Fenton effect of Fe.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.57.1-57.1
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• 2009

나노이산화티타늄은 인체에는 화장품, 의약, 식품분야 등에 쓰이고 외부 환경 재료에는 광촉매로서 유독가스 정화제, 옥내 외 항균, 수소발생 가시광 응답형 촉매 및 멤브레인 필터 등과 전자소재용 유전재료, 발광 재료 등 용도가 다양하다. 나노 산화티타늄 화합물의 제조법은 수열합성법, 기상법 등 여러 방법이 있다. 이들에 대한 리뷰의 목적은 2009년도 정부의 투자 계획 중에서 본제목에 관련되는 핵심 산업 재원 원천기술 개발, 태양광, 풍력 등의 신재생 에너지 개발, 록색 기술 개발을 통한 에너지절약형 LED 개발, 차세대 핵심환경 기술 개발, 핵심나노기반기술개발 등의 개발을 위하여 4,363억 원의 예산을 편성하고 연구자와 기술자들이 참여하여 유익한 실적이 창출되기를 원하고 있으므로 본 발표자들은 이 분야에서 연구하는 연구자와 기술자들에게 이 분야에 관련되는 자료를 참고로 제시하는데 있다. 페로브스카이트형 산화물인 유전재료($BaTiO_3$), 발광재료(CaTiO3:Pr3+적색), 박막형 반응기재료($Ca0.8Sr0.2TiO_3$), 등의 여러 가지 산화물은 류통식 급속 승온 수열 합성법, 겔 졸 법, 수열 합성법 등 여러 방법에 의하여 페로브스카이트형 산화물 입자 직경이 약 20nm~100nm 범위까지 합성된다. 태양광을 조사하여 물을분해 해서 수소를 생산하는 산화티타늄계 가시광 응답형 Vis-$TiO_2$ 박막은 기상법으로 제조하는데 한 예로써 RF 스퍼터링법으로 박막을 제조하여 수소와 산소를 회수하였으며, 황도프산화티타늄, 질소 도프 산화티타늄은 유기물 분해에 의한 공해제거, $NO_x$ 제거 등 환경정화에 사용되고, 고온 고압수법/산화티타늄 복합기술에 의해서는 바이오매스 분해 하고, 일종의 수열법인 개량형 HyCOM 법은 가시광 응답성 산화티타늄을 합성하여 NO가스 제거에 사용한다. 이들 여러 방법에 관한 것을 소개하고저 한다.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.484-490
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• 1999

$(Pb,La)TiO_3$(PLT) thin films were prepared on Pt/SiO$_2$/Si substrates by the sol-gel method and investigated the crystalline and electrical properties according to La concentration and post-annealing temperatures. The PLT films annealed at above $600^{\circ}C$ were exhibited the typical perovskite structures regardless of La contents. When the $(Pb,La)TiO_3$(PT) films were doped with La concentration up to 10mol%(PLT-10), the degree of z-axis orientation was greatly decreased from 63% to 26%. From AES depth profiles for the PLT-10 samples, no remarkable inter-reaction between PLT film and lower Pt electrode was found. The remanent polarization$(2Pr,Pr_+-Pr_-)$ were increased from $4\muC\textrm{cm}^2 to 16\muC\textrm{cm}^2$ as the annealing temperature increased from $600^{\circ}C to 700^{\circ}C$. This result may be ascribed to the improvement of crystallinity by the high temperature post-annealing. The dielectric constant$({\varepsilon}r)$ and tangent loss(tan$\delta$) of the PLT-10 films annealed at $650^{\circ}C$ were about 193 and 0.02, respectively with the pyroelectric coefficient($\gamma$) of around $4.0nC/\textrm{cm}^2{\cdot}^{\circ}C at 30^{\circ}C$.