• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.396-396
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• 2008

투명 전도성 탄소나노튜브(carbon nanotube, CNT) 필름을 터치스크린이나 디스플레이 소자 등의 전극에 응용할 목적으로, CNT 필름의 전기저항 및 광 투과도를 향상시키기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 단일벽 CNT (single-walled CNT)를 여러 가지 계면활성제로 분산시킨 수용액으로부터 제조한 CNT 필름을 산 처리하여 저항 및 투과도의 변화를 관찰하였다. 우선 계면활성제로 분산시킨 CNT 수용액을 알루미나 재질의 필터에서 정량적으로 진공 필터링하여 CNT 필름을 제조하였다. 알루미나 필터를 sodium hydroxide (NaOH) 수용액으로 용해시켜 제거함으로써 얻은 CNT 필름을 유리기판 위에 부착시킨 후 광 투과도와 먼 저항 (sheet resistance)을 측정하였다. CNT 필름을 질산 ($HNO_3$) 용액에 처리하였을 때 투과도는 1~5 % 향상되었으며, 면 저항은 계면활성제로 분산시킨 CNT 필름 대부분에서 감소하였다. 이는 CNT 표면에 코팅되어 있던 계면활성제들이 산에 의해 제거되었기 때문일 것으로 추측된다. 특히 sodium dodecylbenzene sulfonate (NaDDBS)로 제조한 CNT 필름의 경우, 질산을 처리 전에는 투과도 83%, 면 저항 450 $\Omega$/sq.의 특성을 보였으나, 처리 후에는 각각 86 %, 350 $\Omega$/sq.로 향상되었다. Polyvinyl pyrrolidone (PVP)과 cetyltrimethylammonium bromide (CTAB)를 사용하여 제조한 CNT 필름의 면 저항이 가장 뚜렷한 감소를 보였다. 제조된 필름과 삼 처리된 필름 특성을 Raman spectroscopy, scanning electron microscopy, UV-Vis spectroscopy 등을 이용하여 분석하였고, 4-point probe로 면 저항을 측정하였다.

• Analytical Science and Technology
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• v.8 no.2
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• pp.205-213
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• 1995

Counter-diffusion of coronene desorbed from alumina with addition of tetra-phenylporphine was studied by spectrophotometry. The counter-diffusion processes of adsorbing and desorbing materials in liquid phase were simulated by counter-diffusion model based on Fritz's binary component isotherm under an assumption of equimass diffusion. The counter-diffusivities of desorbed coronene with addition of tetra-phenylporphine were as ${\sim}10^{-15}m^2/sec$ and that of adsorbed tetra-phenylporphine as ${\sim}10^{-11}m^2/sec$. The counter-diffusivity of coronene determined from desorption process was smaller by ${\sim}10^5$ times than the diffusivity determined from adsorption process of a single species. The reduction of the determined counter-diffusivity of coronene in desorption process was explained by the cross of diffusion fluxes and build-up of high gradient of coronene in pore.

• Membrane Journal
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• v.19 no.3
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• pp.194-202
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• 2009

In this study periodic water-back-flushing using permeate water was performed to minimize membrane fouling and to enhance permeate flux in advanced water treatment by tubular ceramic ultrafiltration membrane for Gongji stream in Chuncheon city. The back-flushing period (FT, filtration time) 2 min with periodic water-back-flushing of 15 sec showed the highest value of dimensionless permeate flux (permeate flux vs. initial permeate flux), and the lowest value of resistance of membrane fouling. Also in the results of BT effect at fixed FT 10 min, BT (back-flushing time) 20 sec showed the lowest value of resistance of membrane fouling and the highest value of dimensionless permeate flux, and we could be obtained the highest total permeate volume of 107.3 L. Consequently FT 10 min and BT 20 sec could be the optimal condition in Gongji stream water treatment, which was the exactly same results of our previous tubular alumina microfiltration. Then the average rejection rates of pollutants by our tubular ceramic UF system were 97.0% for turbidity, 32.1 % for chemical oxygen demand by manganese method, 28.8% for ammoniac nitrogen and 54.4% for T-P.

• Membrane Journal
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• v.22 no.3
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• pp.216-223
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• 2012

The effect of water back-flushing period (FT) was investigated in hybrid process of carbon fiber microfiltration membrane and photocatalyst for advanced drinking water treatment in this study, and compared with the previous study using alumina ultrafiltration membrane. The FT was changed in the range of 2~10 min with fixed 10 sec of BT. Then, the FT effects on resistance of membrane fouling ($R_f$), permeate flux (J) and total permeate volume ($V_T$) were observed during total filtration time of 180 min. As decreasing FT, $R_f$ decreased and J increased, which was same with the previous result using alumina ultrafiltration membrane. The treatment efficiency of turbidity was high beyond 99.2%, and the effect of FT was not shown on treatment efficiency of turbidity, which was different with the previous result. The treatment efficiency of organic matters was the lowest value of 65.6% at NBF, and it increased as decreasing FT, which was different with the previous result, too. The reason was that the membrane fouling phenomena could show a different mechanism depending on ceramic membrane materials.

• Journal of the Korean Chemical Society
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• v.40 no.4
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• pp.264-272
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• 1996

Cluster models of the Υ-Al2O3(111) and the Pt(111) surfaces have been used in an atom superposition and electron delocalization molecular orbital study of interfacial bond strengths between them. The reduced extents for Al3+ are due to the ratio of oxygen to aluminum atoms. The greater the reduced extent for Al3+ is, the stronger the binding energy is to Pt atoms in a cluster. The oxygen-covered surfaces of Υ-Al2O3(111) are shown to bind more weakly to Pt atoms, while the binding to the oxygen-covered surface formed under oxidizing conditions of Pt atoms is strong. The interfacial bond of platinum-alumina may be possible by a charge-transfer mechanism from the platinum surface to the partially empty O-2p band and Al3+ dangling surface orbital.

• Journal of Conservation Science
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• v.6 no.1 s.7
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• pp.3-14
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• 1997

Twelve Punchong sherds collected in Hakbongni, Kongju where the well known iron-painted on white slip were manufactured from late 15C to early 16C were analyzed for their composition and microstructure. The composition of the body was analyzed by X-ray fluorescence and that of glaze by electron probe micro-analyzer. Microstructure was observed by optical microscope, polarizing microscope, EPMA, and X-ray diffractometer. The results of composition of body and glaze of Hakbongni were compared with those of Punchong from Yongsuri, Boryong which was close to Hakbongni. The composition of body and glaze of these two areas were compared by principal component analysis using SPSS program. Hakbongni bodies have higher silica and flux materials but lower alumina and their glaze have higher silica, soda, iron oxide but lower alumina, calcia. Hakbongni punchong itself is divided into two groups. Their glaze is lime type. There are many remnant minerals, such as quartz, large feldspar mass with partially melted surrounding area, albite, biotite, and iron-oxide. From such a microstructure we can assume that preparation of raw material was rather crude and firing temperature quite low. Iron-painted material is identified as Mg/Fe/Al spinel by composition analysis and XRD pattern.

• Analytical Science and Technology
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• v.13 no.4
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• pp.433-439
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• 2000

Adsorption behaviors of Ni(II) ions were investigated using amorphous alumina as adsorbent. In the adsorption kinetic study, it was observed that Ni(II) ions were bound to the alumina surface in two adsorption stages, the rapid and slow adsorption stages. The rapid adsorption proceeded within 1 hr, thereafter the slow adsorption occurred. The results of adsorption isotherm experiments showed that the Ni(II) adsorption obeyed the Langmuir-Freundlich isotherm, and that the adsorption enhanced with increasing pH. The change in ionic strength did not exhibit a conspicuous trend in Ni(II) adsorption, thereby suggesting that the adsorption occurs through surface complexation rather than electrostatic interactions. The amounts of adsorption were measured with varying pH at three different Ni(II) concentrations under the condition of constant ionic strength, showing that with increasing Ni(II) concentration, the percentage of adsorption decreased and the adsorption edge was shifted to a higher pH value.

• The Journal of Engineering Geology
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• v.29 no.2
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• pp.163-183
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• 2019

We investigated acid mine drainage (AMD) of Bongyang abandoned coal mine, Danyang, Chungbuk Province with emphasis on geochemical contaminants in AMD and precipitates using chemical analyses, XRD, SEM, IR, and $^{27}Al$ NMR. Water chemistry changes with pH and oversaturation of chemical species. According to calculation of saturation index, the AMD is saturated with various Fe, Al minerals. Orange or orcher precipitates are composed of schwertmannite and goethite, associated with Leptothrix orchracea bacteria, whereas whitish precipitates are composed mostly of alumimous minerals such as basaluminite with poor crystallinity. The whitish precipitates include trace $Al_{13}$-Tridecamer. It is important to control the precipitation and solubility of aluminous species for ensuring remediation and control for the AMD discharged from the Bongyang abandoned coal mine.

• Analytical Science and Technology
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• v.21 no.4
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• pp.296-303
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• 2008

This study was performed to establish an analytical method of PAHs in oil contaminated soil of these methods by evaluating the PAHs test methods from US EPA and ISO etc. The application to domestic contaminated soil leads to a conclusion that alumina column is a more effective clean-up procedure for oil contaminated soil rather than the others. It is proposed with the new analytical method of 12 PAHs except for more volatile compounds (naphthalene, acenaphthylene, acenaphthene, fluorene). The recovery of PAHs in this method ranged 67~107%. The oil contaminated soil samples were analyzed using GC/MSD. The concentration of PAHs ranged $78.68{\sim}275.57{\mu}g/kg$. The predominated compounds were fluoranthene, pyrene and chrysene attributing about 70% of total concentration. The level of Benzo[a]pyrene ranged $1.76{\sim}24.65{\mu}g/kg$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.291-291
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• 2009

ZnS:Mn/Cu,Cl 계 나노 형광체의 특성을 살펴보았다. 실험에서는 ZnS:Mn 과 ZnS:Cu,Cl 형광체 파우더를 이용하여 밀링을 통하여 분쇄하여 EL 소자를 제작하였다. 형광체 파우더를 볼밀에 $\Phi5mm$의 지르코나이 볼과 에탄올과 함께 넣고 2, 4, 6, 8, 10일간 밀링을 하였다. 밀링한 형광체 파우더를 SEM을 통하여 파우더의 사이즈를 관찰하였다. 또 이 파우더를 이용하여 EL 소자를 제작하였다. 소자의 구조는 기판은 알루미나 기판을, 하부 전극은 Au, 유전체는 $BaTiO_3$ 유전체 페이스트를 사용하였으며, 형광체 적층 후 ITO 전극을 스퍼터를 이용하여 증착하여 제작하였다. 제작한 소자를 이용하여 소자의 휘도 등 발광 특성을 살펴보았다.