• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.43-48
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• 2020

Fe₂O₃ nanoparticles with the mixed structure of cubic and nanorod were synthesized by precipitation, hydrothermal, sol-gel method, etching process and heat treatment. Fe₂O₃/TiO₂ core-shell (CS) of type Fe₂O₃@TiO₂ composite was fabricated on a 20 nm nanolayer of TiO₂ coated on the surface of Fe₂O₃ nanoparticles. Fe₂O₃/TiO₂ yolk-shell (YS) composite was prepared by chemical etching and heat treatment of Fe₂O₃/TiO₂ CS nanoparticles. Physical properties of Fe₂O₃, Fe₂O₃@TiO₂ CS and Fe₂O₃@TiO₂ YS nanoparticles were characterized by FE-SEM, HR-TEM and X-ray diffraction. The solar reflectance, commission internationale de l'Elcairage (CIE) color coordinate and heat shield temperatures of Fe₂O₃, CS and YS type Fe₂O₃@TiO₂ pigments filled with poly acrylate (PA) paints were investigated by UV-Vis-NIR spectrometer and homemade heat shield temperature measuring device. The Fe₂O₃@TiO₂ YS red pigment filled PA composite exhibited excellent near infrared light reflecting performance and also reduced the heat shield temperature of 13 ℃ than that of Fe₂O₃ filled counterparts.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.1
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• pp.15-26
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• 2017

Cobalt ferrocyanide (CoFC) or nickel ferrocyanide (NiFC) magnetic nanoparticles (MNPs) were fabricated for efficient removal of radioactive cesium, followed by rapid magnetic separation of the absorbent from contaminated water. The $Fe_3O_4$ nanoparticles, synthesized using a co-precipitation method, were coated with succinic acid (SA) to immobilize the Co or Ni ions through metal coordination to carboxyl groups in the SA. CoFC or NiFC was subsequently formed on the surfaces of the MNPs as Co or Ni ions coordinated with the hexacyanoferrate ions. The CoFC-MNPs and NiFC-MNPs possess good saturation magnetization values ($43.2emu{\cdot}g^{-1}$ for the CoFC-MNPs, and $47.7emu{\cdot}g^{-1}$ for the NiFC-MNPs). The fabricated CoFC-MNPs and NiFC-MNPs were characterized by XRD, FT-IR, TEM, and DLS. The adsorption capability of the CoFC-MNPs and NiFC-MNPs in removing cesium ions from water was also investigated. Batch experiments revealed that the maximum adsorption capacity values were $15.63mg{\cdot}g^{-1}$ (CoFC-MNPs) and $12.11mg{\cdot}g^{-1}$ (NiFC-MNPs). Langmuir/Freundlich adsorption isotherm equations were used to fit the experimental data and evaluate the adsorption process. The CoFC-MNPs and NiFC-MNPs exhibited a removal efficiency exceeding 99.09% for radioactive cesium from $^{137}Cs$ solution ($18-21Bq{\cdot}g^{-1}$). The adsorbent selectively adsorbed $^{137}Cs$, even in the presence of competing cations.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.5
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• pp.240-246
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• 2002

$TiO_2$ films on soda-lime-silica glasses were prepared by spin coating-pyrolysis process using titanium naphthenate as a starting material. As-deposited films were pyrolyzed at $500^{\circ}C$ for 10 min in air and annealed at 500, 550 and $600^{\circ}C$ for 30 min in air. Crystallinity of the film was investigated by X-ray diffraction analysis. A field emission-scanning electron microscope and an atomic force microscope were used for characterizing the surface morphology and the surface roughness of the film. After annealing at 550 and $600^{\circ}C$, the X-ray diffraction patterns consist of only anatase peak. Films annealed at 500 and $550^{\circ}C$ exhibited flat surfaces. While with the increase in annealing temperature to $600^{\circ}C$, the $TiO_2$ film showed abnormal growth of three-dimensional needle-shaped grains. For all samples, high transmittance, above 90 % at 500 nm, was obtained at visible range. To investigate photocatalytic properties, IR absorbance associated with the C-H stretching vibrations of a thin solution-cast film of stearic acid under 365 nm (2.4 mW/$\textrm{cm}^2$) UV irradiation was estimated.

• Polymer(Korea)
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• v.30 no.6
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• pp.519-524
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• 2006

Poly(4-vinyl pyridine) (PVP) and its copolymers, poly(4-vinyl pvridine- co-acrylamide) and poly(4-vinyl pyridine-co-allylamine), were synthesized and evaluated for application to organic solder-ability preservatives (OSP). The copolymers were synthesized by radical polymerization of vinyl pyridine in the presence of acrylamide or allylamine as a comonomer. Various kinds of polymers with different chemical composition were synthesized by varying the feed ratio of monomers and their low $M_w$ polymers can be obtained by adding 2-mercaptoethanol as a chain transfer agent during poly-merization. All the polymers showed good adhesion properties on Cu pad when they were spin-coated. Especially, allylamine -containing copolymers showed both good adhesion and solubility properties. Also, they exhibited better thermal stability than PVP homopolymer and such thermal properties were changed depending on the chemical composition and their $M_w$, which were evidenced by the measurement of oxygen induced temperature (OIT). From the OIT measurement, poly(4-vinyl pyridine- co-allylamine) was thermally stable up to $230^{\circ}C$ for 70 min in the 100% oxygen environment. As a result, allylamine-containing copolymers can be considered as a promising OSP coating material that has excellent thermal and adhesive properties applicable to the present microelectronic package processes.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1088-1095
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• 2018

In this study, reduced graphene oxide/polyaniline composite was fabricated tomaximize their advantages with electrochemical performances and use as a electrodematerial for supercapcaitor. Polyaniline as an electrode material was synthesized bychemical polymerization of aniline monomer and reduced graphene oxide wasintroduced to prepare composite with polyaniline without any pre-treatment. Thereduced graphene oxide, polyaniline and their composite electrodes were fabricatedon gold coated PET(polyethylene terephthalate) substrate through spray coatingmethod which can also apply to industrial scale. we have also prepared reducedgraphene oxide and polyaniline single material electrode to compare theirelectrochemical properties with reduced graphene oxide/polyaniline composite electrode. We have analyzed and compared electrochemical properties of eachelectrodes by using cyclic voltammetry(CV), galvanostaticcharge-discharge(GCD) and electrochemical impedancespectroscopy(EIS) at same condition. As a result, reduced graphene oxide /polyaniline composite electrode showed higher capacitance value more thanpolyaniline and reduced graphene oxide electrode, respectively. Internal resistanceof reduce graphene oxide/polyaniline composite electrode was 24% and 58% lessthan polaniline and reduced graphene oxide electrode respectively. These resultsconsidered that reduced graphene oxide/polyaniline composite electrode has potential ability and enable to apply flexible energy storage and wearable devices.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.1
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• pp.15-25
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• 2023

Since the COVID-19 crisis, the use of disposable packaging materials and delivery services, which raise environmental and social issues with waste disposal, has significantly increased. Antimicrobial active packaging has emerged as a viable solution for extending the shelf-life of foods by minimizing microbial growth and decomposition. In this review article, we provide a comprehensive overview of current research trends in antimicrobial active film and coating published over the last five years. First, we introduced various polymer materials such as film and coating that are used in active packaging. Next, various types of antimicrobial (antibacterial, antifungal, and antiviral) packaging including essential oil, extracts, biological material, metal, and nanoparticles were introduced and their activities and mechanisms were discussed. Finally, the current challenges and prospects were discussed. Overall, this review provides insights into the recent advancements in antimicrobial active packaging research and highlights the potential of the technology to enhance food safety and quality.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.65-71
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• 2016

In this study, Antimony Tin Oxide (ATO) ion storage layer and $TiO_2$ working electrode were fabricated using Nano Particle Deposition System. NPDS is the cutting-edge technology among the dry deposition methods. Accelerated particles are deposited on the substrate through the nozzle using NPDS. The thicknesses for coated layers were measured and layer's morphology was acquired using SEM. The fabricated electrochromic cell's transmittance was measured using UV-Visible spectrometer and power source at 630 nm. As a result, the integrated electrochromic/DSSC hybrid system was successfully fabricated as an energy harvesting system. The fabricated electrochromic cell was self-operated using DSSC as a power source. In conclusion, the electrochromic cell was operated for 500 cycles, with 49% of maximum transmittance change. Also the photovoltaic efficiency for DSSC was measured to be 2.55% while the electrochromic cell on the integrated system had resulted in 26% of maximum transmittance change.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.185-185
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• 2012

중공 발광 나노 물질은 특유의 구조적 특성(낮은 밀도, 높은 비표면적, 다공성 물질, 낮은 열팽창계수 등)과 광학적 성질을 이용하여 디스플레이 패널, 광결정, 약물전달체, 바이오 이미징 라벨 등의 다양한 적용이 가능하다. 이러한 적용에 있어 균일한 크기와 형태의 중공 입자는 필수 조건으로 여겨진다. 지금까지 합성된 중공 발광 입자에는 BaMgAl10O17 : Eu2+-Nd3+, Gd2O3 : Eu3+, $EuPO_4{\cdot}H_2O$과 같은 것들이 있으나 크기 조절이 어렵고, 그 균일성이 확보되지 못하였다. 균일한 크기의 중공 발광 입자를 만들기 위해 SiO2나 emulsion을 템플릿으로 이용하여 황화카드뮴, 카드뮴 셀레나이드 중공 입자를 합성한 예가 있으나, 양자점의 독성으로 인하여 바이오분야 응용에는 적합하지 않다. YAG는 모체로써 형광체에서 가장 많이 이용되는 물질로, 화학적 안정성과 낮은 독성, 높은 양자 효율 등 많은 장점을 갖고 있다. 특히 세륨이 도핑된 YAG형광체의 경우 WLED, 신틸레이터, 바이오산업에 적용이 가능하다. 그러나 지금까지 중공 YAG:Ce3+형광체를 합성한 예가 없었다. 본 연구에서는 단분산 수화 알루미늄 (Al(OH)3) 입자 위에 세륨이 도핑 된 이트륨 베이직 카보네이트 ($Y(OH)CO_3$)를 균일하게 코팅한 후 열처리를 하여 균일한 크기의 Y3Al5O12:Ce3+(YAG) 중공 입자를 합성하였다. 열처리 온도에 따른 고분해능 투과 전자 현미경(HRTEM), X-선 회절(XRD), 고분해능 에너지 분광법(HREDX) 분석결과, 중공 YAG: Ce3+입자는 Kirkendall 효과에 의해 형성됨을 확인하였다. 전계방사형 주사 전자 현미경(FE-SEM) 측정을 통해, 열처리 후에도 입자의 크기와 형태가 균일함을 확인하였으며, 공초점 현미경 관찰을 통해 중공 형태를 명확히 확인 할 수 있었다. Photoluminescence (PL) 분광법과 형광 수명 이미징 현미경(FLIM)을 이용한 광 특성 분석결과, 합성된 입자는 400-500 nm에서 흡수 파장 (456 nm에서 최대 강도)과 500-700 nm 범위의 발광 파장(544 nm에서 최대 강도)을 나타냈고, 상용 YAG: Ce3+(70 ns)에 준하는 74 ns의 잔광 시간(decay time)이 측정되었다. 단분산 수화 알루미늄 입자의 크기를 조절하여 최종 합성된 YAG: Ce3+의 크기를 조절할 수 있었다. 지름 약 600 nm의 Al(OH)3를 사용한 경우, $1,300^{\circ}C$에서 열처리를 한 후 평균 지름 590 nm의 중공입자를 합성하였고, 약 170 nm의 Al(OH)3를 이용하여, 더 낮은 온도인 $1,100^{\circ}C$에서의 열처리를 통해 평균지름 140 nm의 중공 YAG: Ce3+입자를 합성하였다. 본 연구를 통하여 합성된 균일한 크기의 YAG 중공입자는 LED와 같은 광전변환 소자 및 다기능성 바이오 이미징 등의 나노바이오 소자 분야에 활용될 수 있음이 기대된다.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.418-423
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• 2009

MWCNT(multi-wall carbon nanotube)-doped PEDOT:PSS(poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)), used as a HIL(hole injection layer) material in OLEDs(organic light emitting diodes), was spin-coated on to the ITO glass to form PEDOT:PSS-MWCNT nano composite thin film. Morphology and transparency characteristics of nano composite thin films with respect to the loading percent of MWCNT have been investigated using FT-IR, UV-Vis and SEM. Furthermore, ITO/PEDOT:PSS-MWCNT/NPD/$Alq_3$/Al devices were fabricated, and then J-V and L-V characteristics were investigated. Functional group-incorporated MWCNT was prepared by acid treatment and showed good dispersion property in PEDOT:PSS solution. PEDOT:PSS-MWCNT thin films possessed good transparency property. For multi-layered devices, it was shown that as the loading percent of MWCNT increased, the current density increased but the luminance dramatically decreased. It might be conclusively suggested that the enhanced charge mobility by MWCNT could increase the current density but the hole trapping property of MWCNT could dramatically decrease the hole mobility in the current devices.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.6
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• pp.277-281
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• 2009

Superhydrophobic $SiO_2$ thin films were successfully fabricated on a glass substrate by sol-gel method. To fabricate $SiO_2$ thin film with a high roughness, $SiO_2$ nano particles were added into tetraethoxysilane (TEOS) solution. The prepared $SiO_2$ thin film without an addition of $SiO_2$ nano particles showed a very flat surface with ca. 1.27 nm of root mean square (RMS) roughness. Otherwise, the $SiO_2$ thin films fabricated by using coating solutions added $SiO_2$ nano particles of 1.0, 2.0 and 3.0 wt% showed a RMS roughness of ca. 44.10 nm, ca. 69.58 nm, ca. 80.66 nm, respectively. To modify the surfaces of $SiO_2$ thin films to hydrophobic surface, a hydrophobic treatment was carried out using a fluoroalkyltrimethoxysilane (FAS). The $SiO_2$ thin films with a high rough surface were changed from hydrophilic to hydrophobic surface after the FAS treatment. Especially, the prepared $SiO_2$ thin film with a RMS roughness of 80.66 nm showed a water contact angle of $163^{\circ}$.