• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.6.2-6.2
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• 2010

Stainless steel is widely known to have superior corrosion properties. However, in some harsh conditions it still suffers various kinds of corrosions such as galvanic corrosion, pitting corrosion, intergranular corrosion, chloride stress corrosion cracking, and etc. For the corrosion protection of stainless steel, the ceramic coatings such as protective silica film can be used. The sol-gel coating technique for the silica film has been extensively studied especially because of the cost effectiveness. It has been proved that silica can improve the oxidation and the acidic corrosion resistance of metal surface in a wide range of temperatures due to its high heat and chemical resistance. However, in the sol-gel coating process there used to engage a heat treatment at an elevated temperature like $500^{\circ}C{\sim}600^{\circ}C$ where cracks in the silica film would be formed because of the thermal expansion mismatch with the metal. The cracks and pores of the film would deteriorate the corrosion resistance. When the heat treatment temperature is reduced while keeping the adhesion and the density of the film, it could possibly give the enhanced corrosion resistance. In this respect, inorganic protective silica film was tried on the surface of stainless steel using a sol-gel chemical route where silica nanoparticles, tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) were used. Silica nanoparticles with different sizes were mixed and then the film was deposited on the stainless steel substrate. It was intended by mixing the small and the large particles at the same time a sufficient consolidation of the film is possible because of the high surface activity of the small nanoparticles and a modest silica film is obtained with a low temperature heat treatment at as low as $200^{\circ}C$. The prepared film showed enhanced adhesion when compared with a silica film without nanoparticle addition. The films also showed improved protect ability against corrosion.

• Reproductive and Developmental Biology
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• 제34권3호
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• pp.175-180
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• 2010

Nanotechnology is currently receiving considerable attention in various fields of biotechnology. The uptake of nanoparticles by cells for labeling and tracking is a critical process for many biomedical therapeutic applications. However, nanoparticle labeling of porcine hematopoietic cells has not been demonstrated so far. In the present study, silica-coated nanoparticles conjugated with rhodamine B isothiocyanate (SR-RITC) were used to investigate the uptake of nanoparticles by porcine hematopoietic cells. Flow cytometric and confocal microscopic analyses reveled that the cells were efficiently internalized by the silica-coated nanoparticles. Furthermore, biocompatibility tests demonstrated that the SR nanoparticles were not cytotoxic, and they had no impact on proliferation. Our study demonstrates that silica-coated nanoparticles are taken up very rapidly and with high efficiency into porcine hematopoietic cells, with no apparent deleterious effects. Therefore, silica-coated nanoparticles appear to be a promising tool for tracking porcine hematopoietic cells.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.218-218
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• 2013

We report a simple and cost-effective method to fabricate transparent superhydrophobic surface on various substrates. The surface was fabricated by coating hydrophobic PDMS (polydimethylsiloxane) film on the silica nanoparticle and subsequent fixing of the hydrophobic silica nanoparticles onto substrates. The water contact angle for the prepared surface was determined to be over $150^{\circ}$, whichindicates that the surface is highly repellent to water. The hierarchical structure and roughness of the surface were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Additionally, transparency of the prepared surface was measured with UV-VIS spectrometer. The transmittance of the superhydrophobic surface was ~80%, which is lower than that without PDMS-coated silica by only 5 to 10%. It is also notable that the superhydrophobic surface fully recovers its original transmittance after self-cleaning process. Also the PDMS coating is stable under a wide range of pH conditions, UV radiation and salinity conditions, which is essential for the practical use. Moreover, our fabrication method is applicable in large scale production.

• 폴리머
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• 제39권2호
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• pp.300-310
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• 2015

본 연구에서는 나노 크기의 실리카 입자 표면을 1차 및 2차 아미노기를 각각 1개씩 가지는 실란 커플링제인 N-[3-(trimethoxysilyl)propyl]ethylenediamine(TPED)으로 개질한 후, 아미노기와 마이클 부가 반응이 가능한 acrylate기를 가지는 3-(acryloyloxy)-2-hydroxypropyl methacrylate(AHM)로 표면 개질하는 연구를 수행하였다. 반응온도, 투입량 및 반응시간과 같은 반응 조건들의 변화가 실리카 표면에 도입되는 methacrylate기의 양에 미치는 영향을 연구하였다. 순수 TPED와 순수 AHM을 $50^{\circ}C$에서 5시간 반응시킨 액체-액체 반응에서는 TPED 1분자 당 존재하는 3개의 아미노기(N-H)들 중 약 85%가 마이클 부가 반응하지만, TPED로 개질한 실리카 표면에 결합한 TPED의 3개의 아미노기는 약 30% 정도만 반응하여 반응성이 매우 낮아짐을 확인하였다.

• 폴리머
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• 제37권6호
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• pp.777-783
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• 2013

본 연구에서는 실리카 나노입자를 dipodal 형태의 bis[3-(trimethoxysilyl)propyl]amine(BTMA) 실란 커플링제로 실리카 표면을 개질한 후, glycidyl methacrylate(GMA)로 표면 처리를 하여 실리카에 결합된 BTMA의 N-H기와 GMA의 epoxide기의 개환 반응에 의하여 실리카 표면에 중합용 methacrylate기를 도입하는 연구를 수행하였다. 반응시간, 반응온도 및 투입하는 GMA의 농도 변화가 BTMA의 N-H기와 GMA의 epoxide기 사이의 반응에 미치는 영향을 Fourier transform infrared spectroscopy(FTIR), elemental analysis(EA) 및 고체상태 $^{13}C$ cross-polarization magic angle spinning(CP/MAS), nuclear magnetic resonance spectroscopy(NMR)법을 사용하여 분석하였다. BTMA로 개질된 실리카를 GMA로 처리하면 실리카 입자에 결합되어 있는 BTMA의 N-H기와 GMA의 epoxide기가 열리면서 상호 반응이 일어났으며, 실험한 조건에서는 반응시간, 반응온도 및 투입하는 GMA 농도가 증가할수록 실리카 표면에 도입되는 methacrylate기가 증가함을 확인하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.652-655
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• 2009

The bimodal porous carbons were synthesized by using imprinting method with templates of SBA-15 particle and silica sphere and applied as supporting materials for the electro-catalyst of polymer electrolyte fuel cell (PEFC). The silica spheres with diameter size of 100 nm and SBA-15 particle having 200 nm -250 nm diameter and 700 nm -900 nm length were synthesized in this work. The bimodal porous carbons (S100) were prepared by using the silica spheres and SBA-15 as templates and mesophase pitch as a carbon source. The PtRu nanoparticle of ca. 1.9 nm were supported on the bimodal porous carbon support and the resulting PtRu/S100 catalysts was tested by the cyclic voltammetry. The use of bimodal porous carbon showed in comparable electro-catalytic activities with commercial catalyst. Though unclear effects of bimodal porosity of supports could be obtained in the scope of this study, morphological advantage in electrical conductivity can be considered on the electro-catalytic activity.

• 한국분말재료학회지
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• 제21권6호
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• pp.441-446
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• 2014

In this study, we synthesize silica-core gold-satellite nanoparticles (SGNPs) for the surface-enhanced Raman scattering (SERS) based sensing applications. They consist of gold satellite nanoparticles (AuNPs) fixed on the silica core nanoparticles, which sizes of AuNPs can be tunned by varying the amount of reactants (growth solution and reducing agent). Their surface plasmon resonance (SPR) properties were characterized by using UV-vis spectroscopy, showing that the growth of AuNPs on silica cores leads to the light absorption in the longer wavelength region. Furthermore, the size increase of AuNPs exhibited the dramatic change in SERS activity due to the formation of hot spots. The optimized SGNPs showing enhancement factor ${\sim}3.8{\times}10^6$ exhibited a detection limit of rhodamine 6G (R6G) as low as $10^{-8}M$. These findings suggest the importance of size control of SGNPs and their SPR properties to develop highly efficient SERS sensors.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.157-158
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• 2006

A novel nanofabrication process has been developed using two-photon crosslinking (TPC) for the fabrication of three-dimensional (3D) SiCN ceramic microstructures applicable to high functional 3D devices, which can be used in harsh working environments requiring a high temperature, a resistance to chemical corrosion, as well as tribological properties. After sequential processes: TPC and pyrolysis, 3D ceramic microstructures are obtained. However, large shrinkage due to low-ceramic yield during the pyrolysis is a serious problem to be solved in the precise fabrication of 3D ceramic microstructures. In this work, silica nanoparticles were employed as a filler to reduce the amount of shrinkage. In particular, the ceramic microstructures containing 40 wt% silica nanoparticles exhibited relatively isotropic shrinkage owing to its sliding free from the substrate during pyrolysis.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.467-467
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• 2011

Reflecting the growing importance of nanomaterials in science and technology, controlling the porosity combined with well-defined structural properties has been an ever-demanding pursuit in the related fields of frontier researches. A number of reports have focused on the synthesis of various nanoporous materials so far and, recently, the nanomaterials with multimodal porosity are getting an emerging importance due to their improved material properties compared with the mono porous materials. However, most of those materials are obtained in bulk phases while the spherical nanoparticles are one of the most practical platforms in a great number of applications. Here, we report on the synthesis of the core-shell silica nanoparticles with double mesoporous shells (DMSs). The DMS nsnoparticles are spherical and monodispersive and have two different mesoporous shells, i.e., the bimodal porosity. It is the first example of the core-shell silica nanoparticles with the different mesopores coexisting in the individual nanoparticles. Furthermore, the carbon and silica hollow capsules were also fabricated via a serial replication process.

• Bulletin of the Korean Chemical Society
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• 제33권1호
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• pp.159-166
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• 2012

We have introduced the Pickering emulsion systems to generate novel confining geometries for the selforganization of monodisperse polymer microspheres using nanoparticle-stabilized emulsion droplets encapsulating the building block particles. Then, through the slow evaporation of emulsion phases by heating, these microspheres were packed into regular polyhedral colloidal clusters covered with nanoparticle-stabilizers made of silica. Furthermore, polymer composite colloidal clusters were burnt out leaving nonspherical hollow micro-particles, in which the configurations of the cluster structure were preserved during calcination. The selfassembled porous architectures in this study will be potentially useful in various applications such as novel building block particles or supporting materials for catalysis or gas adsorption.