• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.134-134
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• 2003

SnO$_2$를 모물질로 하는 가스센서는 n형 산화물 반도체로서 공기중의 산소의 흡탈착 및 전자의 수수에 의해 전기전도도의 변화로 특정 가스를 감지한다. 지금까지 반도체식 가스센서의 모물질로 가장 많이 연구되어 왔지만 아직도 선택성, 안정성 등 여러 가지 문제를 안고 있다. 그리고 개선방안으로 귀금속 촉매의 첨가 및 입자의 크기의 조절 등이 흔히 연구되어 왔다. 따라서 본 연구에서는 순수한 SnO$_2$ 를 이용하여 소결 온도 및 입자 크기에 의한 영향을 CO가스 및 수분에 대한 감도, 반응 시간을 통해 알아보았다. 수열 합성 및 침전 법으로 나노 크기의 SnO$_2$ 분말을 합성하여 스크린 인쇄법으로 후막 가스센서를 제조하였다 침전법에서 SnCl$_4$에 암모니아수로 pH=10.5로 적정하여 SnO$_2$ 분말을 얻었다. 그리고 입자 크기를 조절하기 위해 수열 합성 시 autoclave 내의 수열처리 온도를 100, 150, 20$0^{\circ}C$로 조절하여 SnO$_2$ 분말을 제조하고 입자 크기와 성분분석을 위해 XRD, SEM, TEM, BET 측정을 하였다. 그 결과 침전법으로 제조한 입자의 크기는 20nm 정도였으며 수열 처리한 SnO$_2$ 입자는 10nm이하의 미세한 입자를 얻을 수 있었다. 수열 합성 시 온도가 높아질수록 더 작은 입자 크기를 얻을 수 있었고 600, 7()0, 80$0^{\circ}C$ 열처리 후 입자성장이 침전법에 의한 SnO$_2$ 분말보다 더 작게 일어났다. 이렇게 제조한 나노크기의 SnO$_2$ 분말을 이용하여 습도 및 CO 가스에 대한 그 특실을 평가하였다. CO 20ppm에 대하여 40%정도의 감도를 보였으며 입자가 작아질수록 높은 감도를 보이는 것을 확인 할 수 있었다. 반면 CO 가스와 반응 후 회복 시 입자 의기가 작아질수록 회복이 늦어짐을 알 수 있었다. 그리고 15$0^{\circ}C$에서 습도에 대한 반응 후 회복시간을 조사해보니 같은 결과를 얻을 수 있었다. 이것은 입자 필기가 작아질수록 많은 흡착 사이트를 제공함으로써 높은 감도를 가지지만 반면 다량의 흡착된 가스들이 탈착 하는데 더 많은 시간이 소요되었기 때문이다.

• Korean Journal of Environmental Agriculture
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• v.24 no.2
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• pp.123-131
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• 2005

This study was focused on adsorption, leaching, photolysis, and hydrolysis of the fungicide procymidone in soils. Adsorption type of procymidone on three different soil were well fitted to Linear and Freundlich isotherm. Distribution coefficients (Kd) were ranged from 2.75 to 12.18 and Freundlich isotherm Kf value $1.99{\sim}9.98$, 1/n value $0.74{\sim}0.89$. Desorption rates were $20.1{\sim}34.0%$ (Namgye), $26.3{\sim}44.6%$ (Jigog) and $31.6{\sim}50.9%$ (Baegsan series) and desorption hysteresis were $0.65{\sim}0.79,\;0.55{\sim}0.73\;and\;0.49{\sim}0.68$. Procymidone seemed to be stable to photolysis in acidic and neutral solutions but hydrolyzed rapidly in alkaline solution. Considering leaching properties procymidone mobility low in soils.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.133-138
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• 2009

The continued rise in the number of automobiles on the roads is prompting air pollution to emerge as a serious problem due to the harmful exhaust gas emissions throughout the world. Specifically, based on the exhaust gas regulation in North America represented by PZEV, the regulation on evaporative emission, which originates from the intake manifold system when the engine is stopped, is substantially being intensified. And the technology that can meet and satisfy these regulations has been needed. This study aimed to analyze and evaluate the butane working capacity (BWC) of HC adsorption filter according to the shape of it, which was developed to reduce evaporative emission, and the effect of HC adsorption filter on the engine performance. As a results, HC adsorption filter of the plate type, which was improved compared to that of the corrugated type and also became thinner, indicates higher absorption performance compared to the corrugated one. The absorption performance of the honeycomb type, derived from improving the shape of plate type, is 33.5% higher than that of the corrugated type. However, there was no significant difference in engine performance in all shapes.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.801-805
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• 2008

A fibrous material (p-phenylene-2,5-benzobisoxazole, PBO) was used as an adsorbent for solid phase extraction in order to simplify the extraction procedure. The extraction performance for di-(2-ethylhexyl) phthalate (DEHP) was examined with two types of PBO fibers (HM (High modulus) and AS (Regular type) types) by batch type sorption/desorption experiments. When 100 mg of the HM fibers were applied to 20 mL of the aqueous DEHP solution (less than $50{\mu}g/L$), more than 95% of DEHP was adsorbed on the fibers, however, the AS type fibers adsorbed alkyl phthalate up to 80%. In the case of $50{\mu}g/L$ of the initial concentration of DEHP, the adsorbed DEHP was extracted effectively with methanol and the maximum overall recovery ratio was 92.3%. The results indicated that the PBO fibers could be used as an adsorbent for alkyl phthalate analysis, and that the extraction procedure was not affected by suspended solids in a water sample.

• Membrane Journal
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• v.27 no.5
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• pp.449-457
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• 2017

In this study, the 10 stages stacked module was designed by increasing the number of unit cells in the membrane capacitive deionization(MCDI) process. The aminated polysulfone and sulfonated poly(ether ether ketone) were synthesized and coated on porous carbon electrode by casting method. The salt removal efficiency was measured for the 10 stage stacked module under the operation conditions of adsorption voltage and time, desorption voltage and time, flow rate and concentration of feed water, and di-valent solutions including $CaSO_4$, $MgCl_2$ and tap water. Typically, when 100 mg/L of NaCl as the feed was used, the salt removal efficiency was 98.3% at a flow rate of 100 mL/min, the adsorption condition of 1.2 V/3 min and desorption condition of -0.5 V/5 min.

• Membrane Journal
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• v.28 no.4
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• pp.271-278
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• 2018

In this study, the carbon electrodes using activated carbon fibers (ACFs) were prepared for the capacitive deionization process. The Polyvinylidene fluoride (PVDF) was used as the binder and the mixed ACFs with proper solvent was cast on the commercial graphite sheets to prepare the carbon electrodes. At this moment, the different particle sizes of ACFs were applied and the mixing ratio of solvent, PVDF and ACFs, 80 : 2 : 18 and 80 : 5 : 15, were used for the electrode preparation. Then their salt removal efficiencies were characterized under the various operating conditions, adsorption potential and time, desorption potential and time, concentration of feed NaCl solution and flow rate as well. Typically, the salt removal efficiency of 53.6% were obtained at the particle size below $32{\mu}m$, mixing ratio 80 : 2 : 18, adsorption 1.2 V and 3 min, desorption -0.1V and 1 min, and 15 mL/min flow rate of NaCl 100 mg/L.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.557-564
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• 2000

This study is aimed to develop the adsorbent which can effectively remove toxic hydrophobic organic compounds from the aqueous phase. The emphasis was made to elucidate the adsolubilization behavior of sparingly soluble organic compounds (SSOCs) into the cetyltrimetylammonium bromide(CTAB) layer formed on anthracite by the partition coefficient. The amount of SSOCs removed from aqueous solution was increased with increase of the amount of CTAB coated on the surface and wich increase of SSOCs's hydrophobicity. With the surface-modified solid shown in above. chloroform and benzene at the initial concentration of $6{\times}10^{-4}M$ were removed over 95%. Experimentally determined partition coefficient($K_d$) values between organo-anthracite and organics were 4~25 times higher than theoretical $K_d$ values of same organics Organo-anthracite formed by the addition of the CTAB can effectively immobilize organic contaminants dissolved in landfill leachate and can also be applicable to wastewater treatment containing toxic hydrophobic organic compounds such as chloroform and benzene.

• Journal of Soil and Groundwater Environment
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• v.13 no.4
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• pp.54-61
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• 2008

Permeable reactive barriers (PRBs) technology has been focused in contaminated groundwater remediation. It is necessary to select adequate reactive material according to characteristics of contaminant in groundwater. In this research, the reaction between reactive material and heavy metal contaminants was estimated through column test. Reactive material was slag, which has been produced in Gwangyang power plant, and heavy metal contaminants were cadmium, lead and copper. Column test was performed in the condition of 1) single and multi contaminated solution and 2) different initial concentration of cadmium. Retardation factor of cadmium is 3.94 in multi contamination. But that of copper is 40.3 in single and 25 in multi. The difference of retardation between cadmium and copper is due to affinity, resulted from the difference of electronegativity. In multi-contamination, copper effluent concentration was above initial copper concentration and at the same time lead effluent concentration was decreased. This phenomenon was considered that lead extract copper sorbed in slag and then lead was sorbed to the vacant sorption site instead. And as the initial concentration was increased, the retardation factor of cadmium became decreased.

• KSBB Journal
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• v.15 no.4
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• pp.366-369
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• 2000

The soluble paclitaxel was found in the supernatant of the plant cell cultures of Taxus chinensis, The percentage of soluble paclitaxel depends on paclitaxel concentration in bioreactor. As paclitaxel concentration decreases the percentage of soulbe paclitaxel increases. it is therefore important to develop a new process for the recovery of soluble paclitaxel. The use of hydrophobic resin HP20 gives nearly perfect recovery of paclitaxel in supernatant. The resin was more effective in treatment of th cell and debris free filtrate probably because of the reduced solids content In this case 3 g.l resin and 1 day reaction were enough for recovery the soluble paclitaxel in medium.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.74-79
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• 2016

The effects of scale formation of hardness material caused by electrode reactions on the desalination performance of the membrane capacitive deionization (MCDI) were investigated. During the repeated adsorption and desorption process for the influent containing $Ca^{2+}$ ion, changes in effluent concentration and cell potential with respect to the number of adsorption were analyzed. It was found that $OH^-$ generation at the cathode was initiated at about 0.8 V or more of cell potential. In addition, the scale of $Ca(OH)_2$ was formed on the surface of cathode carbon electrode by combining adsorbed $Ca^{2+}$ ions and $OH^-$ ions generated from electrode reaction. As the scale was forming, the electrical resistance of carbon electrode was increasing, which resulted in the decrease of the adsorption amount. In the case of the operation at 1.5 V cell potential, the adsorption was reduced to 58% of the initial adsorption amount due to the scale formation.