• Membrane Journal
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• v.28 no.2
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• pp.121-128
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• 2018

Terpolymers, which are chemical compounds composed of three different chemical compounds, have rarely been utilized for gas separation membranes. In this study, we demonstrate a simple process to fabricate a composite membrane for $CO_2/N_2$ separation based on a terpolymer synthesized from poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethylmethacrylate)(PBEM), poly(oxyethylene methacrylate)(POEM), and methyl methacrylate (MMA) via free radical polymerization. A solution of the as-synthesized PBEM-PMMA-POEM was coated onto a microporous polysulfone (PSf) support to form a composite membrane. The successful polymerization and the characteristics and morphology of the membrane were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FE-SEM). The gas permeance and $CO_2/N_2$ selectivity of the PBEM-PMMA-POEM terpolymer membrane were measured at $25^{\circ}C$. A maximum $CO_2/N_2$ selectivity of 30.2 was obtained at a $CO_2$ permeance of 57.4 GPU ($1GPU=10^{-6}cm^3$(STP)/($s\;cm^2\;cmHg$)).

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.252-252
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• 2016

최근 학계나 산업계에서 indium tin oxide (ITO)의 높은 전기 전도도 및 광투과율을 이용하여 줄 발열을 기초로 하는 투명 면상 발열체에 대한 연구가 활발히 진행 되고 있다. 하지만 단일 ITO 박막으로 제작한 투명 면상 발열체는 온도가 상승함에 따라 균일하게 발열 되지 않으며, 글라스의 곡면 부분에서 유연성이 부족하여 크랙이 발생하는 다양한 문제점들을 가지고 있다. 이를 해결하기 위해 ITO의 결정화 온도 $160^{\circ}C$ 이상의 고온공정 또는 증착 후 열처리가 필요 하는 추가적인 공정이 필요하다. 따라서 본 연구에서는 단일 ITO 박막의 단점을 개선하는 ITO/Ag/ITO 하이브리드 구조의 투명 면상 발열체를 제작하여 전기적, 광학적 특성을 비교하고 발열량, 온도 균일성, 발열 유지 안정도를 조사하였다. 본 연구에서는 $50{\times}50mm$ 크기의 non-alkali glass (Corning E-2000) 기판 상에 마그네트론 스퍼터링 공정으로 상온에서 ITO/Ag/ITO 박막을 연속적으로 증착 하여 다층구조의 하이브리드 형 투명 면상 발열체를 제조하였다. 박막 증착 파워는 DC (Ag) power 100 W, RF (ITO) power 200 W로 하였으며 ITO박막두께는 40 nm로 고정 시키고 Ag박막 두께는 10 ~ 20 nm로 변화를 주었다. 증착원은 3인치 ITO 단일 타깃(SnO2, 10 wt.%)과 Ag 금속 타깃 (순도 99.99%)을 사용하였으며, 고순도 Ar을 이용하여 방전하였으며 총 주입량은 20 sccm, working pressure는 1.0 Pa을 유지하였다. 증착전 타깃 표면의 불순물 제거와 방전의 안정성을 유지하기 위해 10분간 pre-sputtering을 진행하고 증착하였다. 증착한 박막의 전기적, 광학적 특성은 각각 Hall-effect measurements system (ECOPIA, HMS3000), UV-Vis spectrophotometer (UV-1800, SHIMADZU)으로 측정하였으며, 하이브리드 표면의 구조 및 형상은 field emission-scanning electron microscopy (FE-SEM, Hitachi S-4800)으로 관찰하였다. 또한 투명 면상 발열체의 성능은 0.5 ~ 3 V/cm의 다양한 전압을 power supply (Keithly 2400, USA)를 통해서 시편 양 끝단에 인가한 후 시간에 따른 투명면상 발열체의 표면 온도변화를 infrared thermal imager (IR camera, Nikon)를 이용하여 관찰하였다. 하이브리드 구조를 가진 ITO박막의 두께는 40 nm로 고정 시키고 Ag박막의 두께는 10, 15, 20 nm로 변화를 주었다. 이들 박막의 면저항 값은 각각 5.3, 3.2, $2.1{\Omega}/{\Box}$였으며, 투과도는 각각 86.9, 81.7, 66.5 %였다. 이에 비해 두께 95 nm의 단일 ITO박막의 면저항 값은 $59.5{\Omega}/{\Box}$였으며, 투과도는 89.1 %였다. 하이브리드 구조의 전기적특성은 금속층의 두께가 증가할수록 캐리어 농도 값이 증가함에 따라 비저항 값이 감소되어 면저항 값도 감소된 것이며, 금속 삽입층의 전도특성이 비저항에 큰 영향을 주고 있음을 보여준다. 하지만 금속 층의 두께가 증가할수록 Ag층이 연속적인 막을 형성하여 반사율이 증가함에 따라 투과도가 감소하였다. 따라서 하이브리드 구조를 가진 투명 면상 발열체에 금속 삽입층의 두께 조절은 매우 중요한 인자임을 확인 할 수 있었다. 또한 발열성능을 평가 하기 위해 시편 양 끝단에 3 V전압을 인가한 결과, 금속 삽입층의 두께가 10 nm에서 5 nm씩 증가한 하이브리드 구조를 가진 투명면상 발열체의 최고 온도는 각각 98, 150, $167^{\circ}C$ 였으며, 단일 ITO의 최고 온도는 $32^{\circ}C$였다. 이 것은 동일한 두께 (95 nm)의 단일 ITO 박막과 비교하여 면저항이 낮은 하이브리드 박막의 발열량은 약 $120^{\circ}C$로 발열효율이 매우 우수한 것을 확인 할 수 있었다.

• Journal of Conservation Science
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• v.31 no.3
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• pp.193-214
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• 2015

The green pigments of shamanic paintings (83 items) in the 19~20th century were analyzed with X-ray fluorescent spectrometer(XRF), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (ATR-FTIR). In 60 items, copper and arsenic were detected in green pigments of the paintings by XRF spectra. Cu $K{\alpha}$/As $K{\beta}$ (peak intensity ratio of copper and arsenic) of shamanic paintings of Bokgaedang (shrine), solemn paintings (romance of three kingdoms) of Donggwanwangmyo and unknown enshrined place were 5.93~12.04 and higher compared to 5.67-6.26 of standard emerald greens and 4.01~7.89 of remaining shamanic paintings. The SEM images of crystal forms of copper-arsenic green pigments were various. Crystal forms were divided into oval and round spherulite with intersecting plate crystals and spherulite with agglomerate plate crystals. The crystals of the latter were found in shamanic paintings of Bokgaedang (shrine), solemn paintings (romance of three kingdoms) of Donggwanwangmyo and unknown enshrined place and the former were found in the rest of shamanic paintings. Copper-arsenic green pigments of shamanic paintings were identified as Scheele's green from shamanic paintings of Bokgaedang (shrine) and romance of three kingdoms. Emerald green from the rest of shamanic paintings by ATR-FTIR. From analytical results, it is confirmed that Scheele's green of shamanic paintings of Bokgaedang and romance of three kingdoms was used in the 1850s~1870s and emerald green had been widely used from late 19th century to 1970 in the rest of shamanic paintings.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.41.1-41.1
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• 2009

Aerosol Deposition (AD) is anovel way to fabricate bioactive ceramic coatings in biomedical implants and prostheses applications. In the present work, silicon-substituted hydroxyapatite (HA) coatings on commercially pure titanium were prepared by aerosol deposition using Si-HA powders. The incorporation of silicon in the HA lattice is known to improve the bioactivity of the HA, makingsilicon-substitute HA an attractive alternative to pure HA in biomedical applications. Si-HA powders with the chemical formula $Ca_{10}(PO_4)_6-x(SiO_4)x(OH)_2-x$, having silicon contents up to x=0.5 (1.4 wt%), were synthesized by solid-state reaction of $Ca_2P_2O_7$, $CaCO_3$, and $SiO_2$. The Si-HA powders were characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), and Fourier transform infrared spectroscopy(FT-IR). The corresponding coatings were also analyzed by XRD, scanning electron microscopy (SEM), and electron probe microanalyzer (EPMA). The results revealed that a single-phase Si-HA was obtained without any secondary phases such as $\alpha$- or $\beta$-tricalcium phosphate (TCP) for both the powders and the coatings.The Si-HA coating was about $5\;{\mu}m$ thick, had a densemicrostructure with no cracks or pores. In addition, the proliferation and alkaline phosphatase (ALP) activity of MC3T3-E1 preosteoblast cells grown on the Si-HA coatings were significantly higher than those on the bare Ti and pure HA coating. These results revealed the stimulatory effects induced by siliconsubstitution on the cellular response to the HA coating.

• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.177-182
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• 2008

The Gemological characteristics of B.C. jade from Cassiar Mine, British Colombia, Canada, have been investigated, using polarizing microscopy, Mohs' hardness, refractive index and density measurements, X-ray powder diffraction, X-ray fluorescence spectrometry, ICP-MS, Infrared absorption spectrometry, and DTA/TGA. The B.C. jade is deeply green (spinach peen or olive green) in color and is translucent. It shows a resinous or waxy luster. The principal mineral of the material is tremolite-actinolite solid solution and minor amount of Cr-garnet and unidentified opaque minerals are accompanied. Mohs' hardness value ($5.5{\sim}6$). refractive index (1.62), and specific gravity (3.01) are measured. It is very highly tough and shows hackly fracture. The high Fe content ($Fe_2O_3\;4.14{\sim}4.66\;wt%$) in B.C. jade is attributable to a deepening of green color of the material. The B.C. jade starts to dehydrate at v and dehydration is completed at $1000.8^{\circ}C$, transforming tremolite-actinolite solid solution to enstatite, diopside, quartz, and water in its place. This possible reaction is supported by the weight loss of B.C. jade (1.93 wt%) at $1000.8^{\circ}C$ indicated by TGA curve.

• Korean Journal of Materials Research
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• v.2 no.1
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• pp.3-11
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• 1992

Aluminum sulfate hydrate was prepared using sulfuric acid from Ha-dong kaolin. The effects of calcination-temperature and calcination-time of kaolin, reaction-temperature and reaction-time, and sulfuric acid concentration on the formation of aluminum sulfate hydrate were investigated. The precipitation condition of aluminum sulfate hydrate from sulfuric acid solution was determined. Also, the products heat-treated at different temperatures have been investigated by X-ray diffraction, thermogravimetry, differential thermal analysis, Fourier transform infrared spectrophotometer, scanning electron microscopy, particle size distribution analysis and chemical analysis. In the optimum condition, the conversion of aluminum oxide in kaolin to aluminum sulfate hydrate was 60%. From the results of XRD, TG-DTA, and FT-IR, it is suggested that the aluminum sulfate hydrate is thermally decomposed as follows ; $Al_2(SO_4)_3{\cdot}18H_2O{\rightarrow}Al_2(SO_4)_3{\cdot}6H_2O{\rightarrow}Al_2(SO_4){\rightarrow}\;amorphous\;alumina{\rightarrow}{\gamma}-alumina{\rightarrow}{\delta}-alumina{\rightarrow}{\theta}-alumina{\rightarrow}{\alpha}-alumina$. The purity of alumina powder prepared by calcining aluminum sulfate hydrate at $1200^{\circ}C$ was 99.99 percent.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.606-610
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• 2010

Films consisting of a silicon quantum dot superlattice were fabricated by alternating deposition of silicon rich silicon nitride and $Si_3N_4$ layers using an rf magnetron co-sputtering system. In order to use the silicon quantum dot super lattice structure for third generation multi junction solar cell applications, it is important to control the dot size. Moreover, silicon quantum dots have to be in a regularly spaced array in the dielectric matrix material for in order to allow for effective carrier transport. In this study, therefore, we fabricated silicon quantum dot superlattice films under various conditions and investigated crystallization behavior of the silicon quantum dot super lattice structure. Fourier transform infrared spectroscopy (FTIR) spectra showed an increased intensity of the $840\;cm^{-1}$ peak with increasing annealing temperature due to the increase in the number of Si-N bonds. A more conspicuous characteristic of this process is the increased intensity of the $1100\;cm^{-1}$ peak. This peak was attributed to annealing induced reordering in the films that led to increased Si-$N_4$ bonding. X-ray photoelectron spectroscopy (XPS) analysis showed that peak position was shifted to higher bonding energy as silicon 2p bonding energy changed. This transition is related to the formation of silicon quantum dots. Transmission electron microscopy (TEM) and electron spin resonance (ESR) analysis also confirmed the formation of silicon quantum dots. This study revealed that post annealing at $1100^{\circ}C$ for at least one hour is necessary to precipitate the silicon quantum dots in the $SiN_x$ matrix.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.586-591
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• 2010

Solar cells have been more intensely studied as part of the effort to find alternatives to fossil fuels as power sources. The progression of the first two generations of solar cells has seen a sacrifice of higher efficiency for more economic use of materials. The use of a single junction makes both these types of cells lose power in two major ways: by the non-absorption of incident light of energy below the band gap; and by the dissipation by heat loss of light energy in excess of the band gap. Therefore, multi junction solar cells have been proposed as a solution to this problem. However, the $1^{st}$ and $2^{nd}$ generation solar cells have efficiency limits because a photon makes just one electron-hole pair. Fabrication of all-silicon tandem cells using an Si quantum dot superlattice structure (QD SLS) is one possible suggestion. In this study, an $SiO_x$ matrix system was investigated and analyzed for potential use as an all-silicon multi-junction solar cell. Si quantum dots with a super lattice structure (Si QD SLS) were prepared by alternating deposition of Si rich oxide (SRO; $SiO_x$ (x = 0.8, 1.12)) and $SiO_2$ layers using RF magnetron co-sputtering and subsequent annealing at temperatures between 800 and $1,100^{\circ}C$ under nitrogen ambient. Annealing temperatures and times affected the formation of Si QDs in the SRO film. Fourier transform infrared spectroscopy (FTIR) spectra and x-ray photoelectron spectroscopy (XPS) revealed that nanocrystalline Si QDs started to precipitate after annealing at $1,100^{\circ}C$ for one hour. Transmission electron microscopy (TEM) images clearly showed SRO/$SiO_2$ SLS and Si QDs formation in each 4, 6, and 8 nm SRO layer after annealing at $1,100^{\circ}C$ for two hours. The systematic investigation of precipitation behavior of Si QDs in $SiO_2$ matrices is presented.

• Journal of Sericultural and Entomological Science
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• v.34 no.2
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• pp.32-40
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• 1992

Many studies have been carried out on the graft finishing in order to improve the quality of silk fiber. Various vinyl monomers, for instance, styrene, methylmethacrylate, 2-hydroxyeth-ylmethacrylate and methacrylamide, have been used practically up to date. Among these monomers, methacrylamide has been applied as the most favourable monomer onto silk fibers in recent years. The polymerization mechanism about styrene- and methylmethacrylate-grafted silk fiber has been studied by many researchers. They proposed that free radicals were formed and vinyl monomers were polymerized in silk fibroin by graft polymerization mechanism, while active sites were varied by the types of monomer and initiator as well as by the reaction condition. In general. there is another Opinion that monomers are polymerized and impregnated in the internal side of the fiber by homopolymerization, which has not been proved experimentally yet More than 10 years have been passed since methacrylamide was applied on the silk fiber, and at the present time most finishings are being achieved by methacrylamide. However, no attention has been paid to the polymerization mechanism of the methacrylamide-treated silk fiber yeL In this paper, the treatments of methacrylamide on silk fibers were studied in aqueous solution using potassium persulfate as an initiator. The polymerization mechanism of the methacrylamide-treated silk fibers was investigated and analyzed on the basis of the results of infrared spectroscopy, amino acid analysis and scanning electron microscopy. From the results of these instrumental analyses, it can be suggested that polymerization mechanism about the methacrylamide-treated silk fibers is not performed by graft polymerization which has been accepted generally in styrene and methylmethacrylate-grafted silk fibers. The different mechanism is supposed to be due to the difference in monomer types, initiator types and treatment conditions.

• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.79-92
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• 1992

The Sarisan clay deposits of hydrothermal origin are found in the intensely weathered wto-mica granite in Yeoju area. The major clay minerals of the Sarisan mine are illite and montmorillonite with minor disordered kaolinite, vermiculite, and some interstratified mineral. Clay minerals were studied using various methods including X-ray diffraction, infrared absorption spectroscopy, electron microscopy, and thermal and chemical analyses. Illites occur as discrete illite or highly illitic interstratified mineral. They are of 1M and $2M_1$ polytypes and characterized by a low lattice charge (1.768-0.926 per unit formula), low $K^+$ content (0.741-0.902 per unit formula), and high Si/Al ratio (1.154-1.293) as compared with muscovite. Montmorillonites are highly negative charged and occasionally random-interstratified as I/S with 80-98% smectite. Hydrothermal alteration is more important than later weathering alteration for the formation of illite and montmorillonite clay minerals. The hydrothermal alteration took place through two stages; the formation of illite in the early stage and the formation of montmorillonite in the late stage. Disordered kaolinite and vermiculite are the weathering products of plagioclase and biotite, respectively.