• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.393-393
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• 2010

The biocompatibility of materials used for biomedical applications depends on chemical composition, mechanical stiffness, surface energy, and roughness. The plasma treatment and etching process is a very important technology in the biomedical fields due to possibility of controlling the surface chemistry and properties of materials. In this work, $N_2/H_2$ plasma were treated on single-walled carbon nanotubes (SWCNTs) paper and characterization of treated SWCNTs paper was carried out. Also we investigated neurite outgrowth from SH-SY5Y on treated SWCNTs paper. The results indicated that $N_2/H_2$ plasma-modified SWCNTs paper enhanced neuronal cell adhesion, viability, neurite outgrowth and branching in vitro and exerted a positive role on the health of neural cells.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.252.2-252.2
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• 2013

ZnO nanostructures have a lot of interest for decades due to its varied applications such as light-emitting devices, power generators, solar cells, and sensing devices etc. To get the high performance of these devices, the factors of nanostructure geometry, spacing, and alignment are important. So, Patterning of vertically- aligned ZnO nanowires are currently attractive. However, many of ZnO nanowire or nanorod fabrication methods are needs high temperature, such vapor phase transport process, metal-organic chemical vapor deposition (MOCVD), metal-organic vapor phase epitaxy, thermal evaporation, pulse laser deposition and thermal chemical vapor deposition. While hydrothermal process has great advantages-low temperature (less than $100^{\circ}C$), simple steps, short time consuming, without catalyst, and relatively ease to control than as mentioned various methods. In this work, we investigate the dependence of ZnO nanowire alignment and morphology on si substrate using of nanosphere template with various precursor concentration and components via hydrothermal process. The brief experimental scheme is as follow. First synthesized ZnO seed solution was spun coated on to cleaned Si substrate, and then annealed $350^{\circ}C$ for 1h in the furnace. Second, 200nm sized close-packed nanospheres were formed on the seed layer-coated substrate by using of gas-liquid-solid interfacial self-assembly method and drying in vaccum desicator for about a day to enhance the adhesion between seed layer and nanospheres. After that, zinc oxide nanowires were synthesized using a low temperature hydrothermal method based on alkali solution. The specimens were immersed upside down in the autoclave bath to prevent some precipitates which formed and covered on the surface. The hydrothermal conditions such as growth temperature, growth time, solution concentration, and additives are variously performed to optimize the morphologies of nanowire. To characterize the crystal structure of seed layer and nanowires, morphology, and optical properties, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) studies were investigated.

• 동의생리병리학회지
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• 제21권3호
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• pp.647-651
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• 2007

It has been well established that S. mutans is the major etiological agent in dental caries, one of the most common oral diseases worldwide. The present study was designed to investigate the effect of Saururus chinensis (S. chinensis) ethanol extracts on the growth, acid production, biofilm formation, adhesion, and insoluble glucan synthesis of S. mutans. The ethanol extracts of S. chinensis showed concentration dependent inhibitory activity against the growth and acid production of S. mutans, and produced significant inhibition at the concentration of 0.025, 0.05, 0.1, 0.2 and 0.4 mg/ml compared to the control group. The extracts markedly inhibited S. mutans adherence to HA treated with saliva, and cell adherence was repressed by more than 80% at the concentration of 0.05 mg/ml and complete inhibition was observed at the concentration of 0.4 mg/ml. On the activity of glucosyltransferase which synthesizes water insoluble glucan form sucrose, ethanol extract of S. chinensis showed more than 10% inhibition over the concentration of 0.025 mg/ml. The synthesis of insoluble glucan was decreased in the presence of 0.025 ${\sim}$ 0.4 mg/ml of the ethanol extract of S. chinensis. Our research strongly suggested S. chinensis was a promising natural product for the prevention of dental caries.

• 한국표면공학회지
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• 제40권4호
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• pp.170-174
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• 2007

High Velocity Oxygen Fuel (HVOF) thermal spray coating of nano size WC-Co powder (nWC-Co) has been studied as one of the most promising candidate for the possible replacement of the traditional hard plating in some area which causes environmental and health problems. nWC-Co powder was coated on Inconel 718 substrates by HVOF technique. The optimal coating process obtained from the best surface properties such as hardness and porosity is the process of oxygen flow rate (FR) 38 FMR, hydrogen FR 57 FMR and feed rate 35 g/min at spray distance 6 inch for both surface temperature $25^{\circ}C\;and\;500^{\circ}C$. In coating process a small portion of hard WC decomposes to less hard $W_2C$, W and C at the temperature higher than its decomposition temperature $1,250^{\circ}C$ resulting in hardness decrease and porosity increase. Friction coefficient increases with increasing coating surface temperature from 0.55-0.64 at $25^{\circ}C$ to 0.65-0.76 at $500^{\circ}C$ due to the increase of adhesion between coating and counter sliding surface. Hardness of nWC-Co is higher or comparable to those of other hard coatings, such as $Al_2O_3,\;Cr,\;Cr_2O_3$ and HVOF Tribaloy 400 (T400). This shows that nWC-Co is recommendable for durability improvement coating on machine components such as high speed spindle.

• 방사선산업학회지
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• 제5권4호
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• pp.371-376
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• 2011

The surface property of the materials used in tissue engineering application has been essential to regulate cellular behaviors by directing their adhesion on the materials. To modulate surface property of the synthetic biodegradable materials, a variety of surface modification techniques have used to introduced surface functional groups or bioactive molecules, recently polydopamine coating method have been introduce as a facile modification method which can be coated on various materials such as polymers, metals, and ceramics regardless of their surface property. However, there are no reports about the degree of polydopamine coating on the materials with different hydrophilicity. In the present study, we prepared acrylic acid grafted nanofibrous meshes using electron-beam irradiation, and then coated meshes with polydopamine. Polydopamine successfully coated on the all meshes, both properties of acrylic acid and polydopamine were detected on the meshes. In addition, the degree of polydopamine deposition on the materials has been altered according to surface hydrophilicity, which was approximately 8-times greater than those on the non-modified materials. In conclusion, dual effect from the acrylic acid grafting and polydopamine may give a chance as a alternative tool in tissue engineering application.

• Journal of Korean Neurosurgical Society
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• 제64권6호
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• pp.853-863
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• 2021

Objective : Biodegradable poly-L-lactic acid (PLLA) with a highly biocompatible surface via tantalum (Ta) ion implantation can be an innovative solution for the problems associated with current biodegradable stents. The purpose of this study is to develop a Taimplanted PLLA stent for clinical use and to investigate its biological performance capabilities. Methods : A series of in vitro and in vivo tests were used to assess the biological performance of bare and Ta-implanted PLLA stents. The re-endothelialization ability and thrombogenicity were examined through in vitro endothelial cell and platelet adhesion tests. An in vivo swine model was used to evaluate the effects of Ta ion implantation on subacute restenosis and thrombosis. Angiographic and histologic evaluations were conducted at one, two and three months post-treatment. Results : The Ta-implanted PLLA stent was successfully fabricated, exhibiting a smooth surface morphology and modified layer integration. After Ta ion implantation, the surface properties were more favorable for rapid endothelialization and for less platelet attachment compared to the bare PLLA stent. In an in vivo animal test, follow-up angiography showed no evidence of in-stent stenosis in either group. In a microscopic histologic examination, luminal thrombus formation was significantly suppressed in the Ta-implanted PLLA stent group according to the 2-month follow-up assessment (21.2% vs. 63.9%, p=0.005). Cells positive for CD 68, a marker for the monocyte lineage, were less frequently identified around the Ta-implanted PLLA stent in the 1-month follow-up assessments. Conclusion : The use of a Ta-implanted PLLA stent appears to promote re-endothelialization and anti-thrombogenicity.

• Nano
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• 제13권12호
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• pp.1850137.1-1850137.9
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• 2018

A series of silica surface-capped with hexamethyldisilazane (denoted as $H-SiO_2$) were prepared by liquid-phase in-situ surface-modification method. The as-obtained $H-SiO_2$ was incorporated into acrylic amino (AA) baking paint to obtain AA/$H-SiO_2$ composite extinction paints and/or coatings. $N_2$ adsorption-desorption tests were conducted to determine the specific surface area as well as pore size and pore volume of $H-SiO_2$. Moreover, the effects of $H-SiO_2$ matting agents on the physical properties of AA paint as well as the gloss and transmittance of AA-based composite extinction coatings were investigated. Results show that $H-SiO_2$ matting agents possess a large specific surface area and pore volume than previously reported silica obtained by liquid-phase method. Besides, they have better dispersibility in AA baking paint than the unmodified silica. Particularly, $H-SiO_2$ with a silica particle size of $6.7{\mu}m$ and the dosage of 4% (mass fraction) provides an extinction rate of 95.2% and a transmittance of 79.3% for the AA-based composite extinction coating, showing advantages over OK520, a conventional silica matting agent. Along with the increase in the silica particle size, $H-SiO_2$ matting agents cause a certain degree of increase in the viscosity of AA paint as well as a noticeable decrease in the gloss of the AA-based composite extinction coating, but they have insignificant effects on the hardness and adhesion to substrate of the AA-based composite coatings. This means that $H-SiO_2$ matting agents could be well applicable to preparing low-viscosity and low-gloss AA-based matte coatings.

• 한국응용과학기술학회지
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• 제36권2호
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• pp.524-530
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• 2019

본 연구에서는 가죽 스킨층에 코팅용으로 사용할 수용성 폴리우레탄의 합성을 위해 polyrupopylene mono methyl ether (PM)를 기반으로 폴리 에테르 폴리올인 폴리 프로필렌 글리콜과 이소포론 디 이소시아네이트 (isophorone diisocyanate, IPDI)를 합성 하였다. 예비 중합체의 합성 후, 점도 상승을 억제하기 위해 $40^{\circ}C$에서 1M, 2M, 3M 및 4M으로 PM을 첨가하고 중화 반응 및 사슬연장 반응을 수행하여 폴리 우레탄 시료를 준비 하였다. 준비된 시료의 인장강도와 연신율, 접착강도를 측정한 결과로 인장강도는 PM 이 1M 일 때 2.109 kgf/mm2, 4M 에서 1.721kgf/mm2, 연신율은 PM이 1M일 때 496%, 4M 에서 522%, 접착력은 PM이 1M 일 때 1.114 kgf/cm, 4M 에서 0.99 kgf/cm 로 확인 되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제23권4호
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• pp.145-151
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• 2019

급속공사 현장에 사용되는 속경성 보수모르타르의 내구성능 증진을 위해 사용재료의 물리적 성능을 평가하였다. 이를 위해 염화물 확산 억제 성능을 보유한 페로니켈 수쇄슬래그 잔골재와 급결제, EVA계 폴리머를 모르타르에 치환시켜 급결성능과 기초적 성능을 평가하였다. 그 결과 FNS잔골재 및 RS잔골재 사용에 따른 압축강도, 휨강도, 부착강도가 증가되었다. 속경성 폴리머 모르타르의 염화물 이온 촉진시험의 결과 FNS를 50%이하 사용 시 재령 7일에서 재령 28일간 염화물 억제 성능이 유지되었으며, FNS잔골재 및 RS잔골재 사용에 따른 내구성 저하는 발견되지 않았으나, 건축 및 토목용 대체골재로 사용하는데 경제성 및 장기 내구성에 대한 추가 검토가 필요할 것으로 판단된다.

• 공업화학
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• 제30권3호
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• pp.352-357
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• 2019

본 연구에서는 3-butenoic acid와 폴리옥시에틸렌(20) 스테아릴 에테르를 사용하여 비닐기를 가진 반응성 유화제를 합성하였다. 합성 반응성 유화제는 FT-IR 및 $^1H-NMR$에 의해 확인되었다. 또한, 아크릴계 점착제의 제조에서 합성된 반응성 유화제와 통상적으로 사용되는 비이온성 유화제를 사용하여 각각의 점착제의 특성을 비교하였다. 고형분 함량은 56.8~57.4%의 범위에서 측정되었다. 초기 접착의 경우, 반응성 유화제로 제조된 S20BA는 $^{\sharp}13$으로 측정되었다. 제조된 접착제의 박리강도는 $0.66{\sim}1.05kg_f$의 범위에서 측정되었고 S20BA를 사용한 경우 가장 높은 박리 강도가 측정되었다. 내열성 시험 결과, S20BA의 내열성이 $840^{\circ}C$로 가장 높았다. 피부용 접착제에 대한 응용성을 평가하기 위하여 pH는 중성 7로 측정되었으며, 일차 피부 자극 시험의 결과로 비자극성으로 측정되었다.