• 한국표면공학회지
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• 제54권3호
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• pp.144-151
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• 2021

In the present work, planar-type ZnO powder of [0001] plane with a high aspect ratio range of 20:1 to 50:1 was synthesized. Ag or CuO could be coated on the planar-type ZnO powder by wet methods such as centrifugation or ball milling. During the coating, the average size of the powder was slightly increased while maintaining the shape and XRD pattern of ZnO. When Ag or CuO was coated, the absolute value of the zeta potential, as well as the concentration of oxygen vacancy, was increased. Ag or CuO coated planar-type ZnO power exhibited excellent antibacterial performance, which seems to be related to their high electrostatic attraction force. They could be made into a masterbatch by mixing with ABS resin, and their applicability to antibacterial substances was confirmed by manufacturing the caps of a keyboard.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1087-1090
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• 2008

Present research is devoted to the development of optical sheet intended to be used inside LCD Backlight unit in order to improve output axial Luminance. It deals with refractive by nature optical sheet having relief embossed top surface (microlenses array). Patterned reflecting layer can be coated on flat bottom surface.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
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• pp.104-104
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• 2011

• 분석과학
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• 제19권6호
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• pp.468-472
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• 2006

기능성 화장품 원료로서 관심을 갖는 비타민 C(L-ascobic acid)는 피부에 대한 안전성, 항산화성으로 인해 노화방지 및 미백, 잔주름개선 등의 효능을 갖지만 화학적으로 쉽게 산화된다. 따라서 본 연구에서는 비타민 C의 안정성에 대한 단점을 보완하기 위하여, 에멀젼 중합법으로 다양한 마이크론 크기의 Polymethylmethacrylate(PMMA)입자를 제조하고, 제조된 PMMA의 입자 표면에 코팅용액(물과 에탄올 혼합용매에 cyclodextrin과 비타민 C를 녹인 용액)을 이용하여 비타민 C를 코팅처리 하였다. 코팅처리 후, 실온 및 $40^{\circ}C$에서 시간에 따른 비타민 C의 함량을 조사한 결과, 56일이 경과후에도 비타민 C가 86.4%가 잔존함을 확인 할 수 있었다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.233-233
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• 2006

[ $Y_{2}O_{2}S:Eu$ ], a red phosphor, coated with silica nanoparticles or nanocomposites composed of silica nanoparticles and polymeric materials such as PMMA and PVP was prepared via sol-gel process. Samples were prepared from four different methods coded P1, P2, P3, and P4. P1 includes a conventional sol-gel process and a dip-coating method while P2 has the same procedure with P1 except that nanocomposites containing both silica nanoparticles and polymer prepared by sol-gel process were used as coating materials. In P3 method, phosphors were dispersed in a solution containing silica precursor, i.e., TEOS and then polymerization was performed to coat onto the phosphors surface while P4 followed the same procedure with P3 except that a solution containing both TEOS and organic monomer were used in preparing coating materials. Among various coating methods examined in this study, uniform coating of phosphor could be achieved by using method P4, i.e., phosphor surface coating in a solution containing hydrophobic monomer and TEOS. Furthermore, $Y_{2}O_{2}S:Eu$ red phosphor coated with nanocomposite composed of PMMA matrix and silica nanoparticles exhibited enhanced PL intensity and long-term stability.

• 전기화학회지
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• 제11권1호
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• pp.37-41
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• 2008

The effects of carbon-coated silicon anode on the electrochemical properties and structural change were investigated. The carbon-coated silicon powders have been prepared by thermal decomposition under argon/10wt% propylene mixed gas flow at $700^{\circ}C$. The surface and crystal structure of the synthesized materials were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Lithium cells with electrodes made from the uncoated and the carbon coated silicon anode were assembled and tested. The carbon-coated silicon particles merged together well after the insertion/extraction of lithium ions, and showed a relatively low irreversible capacity compared with the uncoated silicon particle.

• 한국재료학회지
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• 제20권4호
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• pp.194-198
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• 2010

Cubic boron nitride (c-BN) is a promising material for use in many potential applications because of its outstanding physical properties such as high thermal stability, high abrasive wear resistance, and super hardness. Even though 316L austenitic stainless steel (STS) has poor wear resistance causing it to be toxic in the body due to wear and material chips, 316L STS has been used for implant biomaterials in orthopedics due to its good corrosion resistance and mechanical properties. Therefore, in the present study, c-BN films with a $B_4C$ layer were applied to a 316L STS specimen in order to improve its wear resistance. The deposition of the c-BN films was performed using an r.f. (13.56 MHz) magnetron sputtering system with a $B_4C$ target. The coating layers were characterized using XPS and SEM, and the mechanical properties were investigated using a nanoindenter. The friction coefficient of the c-BN coated 316L STS steel was obtained using a pin-on-disk according to the ASTM G163-99. The thickness of the obtained c-BN and $B_4C$ were about 220 nm and 630 nm, respectively. The high resolution XPS spectra analysis of B1s and N1s revealed that the c-BN film was mainly composed of $sp^3$ BN bonds. The hardness and elastic modulus of the c-BN measured by the nanoindenter were 46.8 GPa and 345.7 GPa, respectively. The friction coefficient of the c-BN coated 316L STS was decreased from 3.5 to 1.6. The wear property of the c-BN coated 316L STS was enhanced by a factor of two.

• 한국재료학회지
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• 제32권8호
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• pp.354-360
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• 2022

In this study, an Co/Fe coated porcelain using a cobalt and ferrous sulfate was sintered at 1,250 ℃. The specimens were investigated by HR-XRD, FE-SEM (EDS), Dilatometer, and UV-vis spectrophotometer. The surface of the porcelain was uniformly fused with the pigment, and white ware and celadon body specimens were densely fused to a certain thickness from the surface. Other new compounds were produced by the chemical reaction of cobalt/ferrous sulfate with the porcelain body during the sintering process. These compounds were identified as cobalt ferrite spinel phases for white ware and white mixed ware, and an andradite phase for the celadon body, and the amorphous phase, respectively. As for the color of the specimens coated with cobalt and ferrous mixed pigments, it was found that the L^* value was greatly affected by the white ware, and the a^* and b^* values were significantly changed in the celadon body. The L^* values of the specimens fired with pure white ware, celadon body, and white mix ware were 72.1, 60.92, 82.34, respectively. The C7F3 pigment coated porcelain fired at 1,250 ℃ had L^* values of 39.91, 50.17, and 40.53 for the white ware, celadon body, and white mixed ware, respectively; with a^* values of -1.07, -2.04, and -0.19, and at b^* values of 0.46 and 6.01, it was found to be 4.03. As a new cobalt ferrite spinel phase was formed, it seemed to have had a great influence on the color change of the ceramic surface.

• 대한치과보철학회지
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• 제44권5호
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• pp.617-627
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• 2006

Statement of problem: HA has been used as a coating material on Ti implants to improve osteoconductivity. However. it is difficult to form uniform HA coatings on implants with complex surface geometries using a plasma spraying technique. Purpose : To determine if Ti6Al4V sintered porous-surfaced implants coated with HA sol-gel coated and hydrothermal treated would accelerate osseointegration. Materials and Methods : Porous implants which were made by electric discharge were used in this study. Implants were anodized and hydrothermal treatment or HA sol-gel coating was performed. Hydrothermal treatment was conducted by high pressure steam at $300^{\circ}C$ for 2 hours using a autoclave. To make a HA sol, triethyl phosphite and calcium nitrate were diluted and dissolved in anhydrous ethanol and mixed. Then anodized implant were spin-coated with the prepared HA sols and heat treated. Samples were soaked in the Hanks solution with pH 7.4 at $37^{\circ}C$ for 6 weeks. The microstructure of the specimens was observed with a scanning electron microscope (SEM), and the composition of the surface layer was analyzed with an energy dispersive spectroscope (EDS). Results : The scanning electron micrographs of HA sol-gel coated and hydrothermal treated surface did not show any significant change in the size or shape of the pores. After immersion in Hanks' solution the precipitated HA crystals covered macro- and micro-pores The precipitated Ca and P increased in Hanks' solution that surface treatment caused increased activity. Conclusion : This study shows that sol-gel coated HA and hydrothermal treatment significantly enhance the rate of HA formation due to the altered surface chemistry.

• Corrosion Science and Technology
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• 제23권4호
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• pp.283-288
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• 2024

Hot-dip Zn-Mg-Al coatings have a complex microstructure consisting of Zn, Al, and MgZn₂ phases. Its crystal structure depends on alloy content and cooling rates. Microstructure and corrosion resistance of these coatings might be affected by heat treatment. To investigate effect of heat treatment on microstructure and corrosion resistance of Zn-Mg-Al coatings, Zn-1.5%Mg-1.5%Al coated steel was heated up to 550 ℃ at a heating rate of 80 ℃/s and cooled down to room temperature. At above 500 ℃, the ternary phase of Zn-MgZn₂-Al was melted down. Only Zn and MgZn₂ phases remained in the coating. Heat- and non-heat-treated specimens showed similar corrosion resistance in Salt Spray Test (SST). When a Zn-3.0%Mg-2.5%Al coated steel was subjected to heat treatment at 100 ℃ or 300 ℃ for 200 h and compared with GA and GI coated steels, the microstructure of coatings was not significantly changed at 100 ℃. However, at 300 ℃, most Al in the coating reacted with Fe in the substrate, forming a Fe-Al compound layer in the lower part of the coating. MgZn₂ was preferentially formed in the upper part of the coating. As a result of SST, Zn-Mg-Al coated steels showed excellent corrosion resistance, better than GA and GI.