• Membrane Journal
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• v.11 no.4
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• pp.161-169
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• 2001

Single and mixed particle suspensions of kaolin, bentonite, starch and PMMA were carried out using a dead-end Amicon fi1tration cell with microfilteration membranes. The experimental data of permeate fluxes were fitted by the constant pressure fi1tration models in order to investigate fouling steps. In 0.1 wt% mixed solution of equal amount of kaolin and starch, the permeation flux was about 30% lower than the average of each particle flux. However, the permeation flux for kaolin/PMMA mixed solution was about 10% higher than the average of each particle flux. In the cases of bentonite and PMMA or starch mired solution, the improvement effect on permeation flux was weaken than that of kaolin mixed solution. Also, the membrane fouling resistance for mixed particle solution of equal amount of kaolin and starch was minimum at 0.05 wt% particle concentration.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.64-64
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• 2011

최근 환경 및 에너지 자원화 문제의 대두는 국내뿐만 아니라 전세계적으로 화석원료를 대체할 수 있는 기술의 개발을 요구하고 있다. 이러한 대체 기술 중에서 무한한 태양 에너지를 사용할 수 있는 기술의 개발은 현대 과학자들뿐만 아니라 인류가 궁극적으로 해결해야 하는 미래기술 중에서도 가장 중요하며 시급한 기술이다. 현재 염료감응태양전지는 저비용과 고효율을 대표하고 있으며 많은 연구자들이 상업화를 위하여 끝임없는 연구를 진행하고 있다. 가장 대표적으로는 요오드와 요오드 염을 사용하는 용액상 연료감응 태양전지가 있으며 11%의 고효율을 보이고 있지만 작동 온도에서 외부열에 의한 용액의 누수 및 반응성에 의하여 소자의 장기안정성이 보장되지 않는 단점을 가지고 있다. 이러한 단점을 극복하고자 용액상 전해질을 대체하려는 연구가 진행되고 있다. 본 강의에서는 이러한 용액상을 대체하려는 최근의 연구 동향 및 효율과 장기안정성을 확보하고자 하는 많은 연구자들의 노력 및 결과들에 대하여 논의하고자 한다.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.599-601
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• 2006

본 논문에서는 용액의 농도가 이온교환 특성에 미치는 영향을 조사하기 위하여 농도는 $Na^+\;50$, 125, 250ppm, $Cl^-\;165$, 315, 610ppm, 입자성 물질의 유입 농도 0ppm, 유속 500ml/min, 이온교환 수지는 ROHM&HAAS IR 120 양이온 수지와 ROHM&HAAS IRA 402 음이온 수지를 사용하였다. 수지탑 배열은 혼상-혼상-음이온 수지탑 순으로, 이온교환 수지탑의 양 음이온교환 수지의 조성 비율은 1:2 로 실험한 결과 이온교환 수지탑 성능은 유입 용액 성분 및 농도에 영향을 받는 것으로 나타났다. 이온교환 수지탑 배열 순서에 따라 파과시점이 연장되며, 파과순서는 음이온의 경우 $Cl^-\;<\;NO_3\;^-\;<\;F^-$, 양이온의 경우 $Na^+\;<\;K^+\;<\;Ca^{2+}$ 순 이였으며, 용액의 농도가 증가할수록 파과시간이 단축되었다.

• Journal of the Korean Chemical Society
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• v.53 no.6
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• pp.663-670
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• 2009

Performing random number simulations, we obtained an approximate distribution of the number of ways arranging molecules in a binary lattice solution of nonrandom mixing with a specific interaction. From the distribution an approximate equation of excess Gibbs energy for a binary lattice solution was derived. Using the equation, liquid-vapor equilibrium at constant pressure for 15 binary solutions were calculated and compared with the result from Wilson equation, Van Laar equation and Redlich-Kister equation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.4
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• pp.584-594
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• 1996

For the separation and purification of aluminium chloride hexahydrate crystals from kaolin leaching solution the effects of crystallization conditions, such as crystallization temperature, concentration of aluminium chloride concentration in the leaching solutin and gas flow rate of HCl into the leaching solution, on purity of the aluminium chloride hexahydrate crystals were investigated. The supersaturation level of aluminium chloride in the leaching solution gave great influence on the purity of the crystals. When supersaturated concentration of the aluminium chloride in the leaching solution was generated in low level, the aluminium chloride hexahydrate crystals were produced with high purity ; that is, the crystals hving a low Fe-ion concentration. The supersaturation level of aluminium chloride in the leaching solution was mainly determined by crystallization temperature, concentrations of aluminium chloride and hydrochloric acid in the solution. However, in spite of changes of the above crystallization coditions, a needle shape morphology of aluminium chloride hexahydrate crystals did not modified. To measure hydrochloric acid concentration in the kaolin leaching solution, we applied the oxalate titration method, which was suggested by shank [9] and it was prove that this method could titrate hydrochloroic acid concentration in multi-component ionic solution such as kaolin leaching solution.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.417-424
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• 2015

In this study, the pretreatment of Helianthus tuberosus residue had been performed. The two-stage pretreatment on flow-through process were applied in the interests of increase of sugar production yield on enzymatic saccharification. The delignification by aqueous ammonia and the fractionation of hemicellulose by sulfuric acid solution as pretreatment solution were confirmed for effects of enzymatic saccharification. Two-stage pretreatment process was performed using aqueous ammonia and sulfuric acid. The first step was performed with aqueous ammonia for 40 min at $163.2^{\circ}C$ and the second step was performed with sulfuric acid solution for 20 min at $169.7^{\circ}C$. And then, the first step was performed with sulfuric acid solution and the second step was pretreated with aqueous ammonia. At this time, the glucose production was 30.7 g and the glucose yield was 72.4% in the first step process with aqueous ammonia. And, the glucose production was 20.9 g and the glucose yield was 49.3% in the first step process with sulfuric acid solution.

• KSBB Journal
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• v.11 no.6
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• pp.676-680
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• 1996

The characteristics of controlled drug release were studied for a biodegradable drug delivery system. A biodegradable chitosan matrix was prepared after swelling chitosan with 10%-acetic acid and adding sulfadiazine. The release behavior of sulfadiazine from the chitosan matrix was studied using the Higuchi's diffusion controlled model in phosphate buffer solutions of pH 7.4 and pH 1.2. The drug release time was delayed by increasing the content of sulfadiazine. The drug release at pH 7.4 was more delayed than that at pH 1.2. The reason is that chitosan has greater swelling abilities at low pH than at high pH. The apparent release rate constant(K) increased as the concentration of drug increased. In shoat, the formulation the biodegradable chitosan matrix to suppress the burst effect of drug release mechanism, which led to a sustained release pattern.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.49-53
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• 2022

In this study, quantum dot light-emitting diodes (QLEDs) of the optimized EL performance with a radio frequency (RF) sputtered Zn_0.85Mg_0.15O thin film as an electron transport layer (ETL). In typical QLEDs, ZnO nanoparticles (NPs) are widely used materials for ETL layer due to their advantages of high electron mobility, suitable energy level and easy capable of solution processing. However, the instability problem of solution-type ZnO NPs has not yet been resolved. To solve this problem, ZnMgO thin film doped with 15% Mg of ZnO was fabricated by RF sputtering and optimized for the device applied as an ETL. The QLEDs of optimized ZnMgO thin film exhibited a maximum luminance of 15,972 cd/m² and a current efficiency of 7.9 cd/A. Efficient QLEDs using sputtering ZnMgO thin film show the promising results for the future display technology.

• Journal of Biomedical Engineering Research
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• v.19 no.6
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• pp.595-602
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• 1998

Among the apex locators, the frequency dependent type is more accurate and convenient to use than others, But the accuracy of the apex locator is still influenced by the presence of various electrolytes used in root canal treatments. In this study, we have developed a frequency dependent electronic apex locator minimizing the influence of the electrolytes on the measurement of root canal lengths. It was also confirmed that two frequencies of 500Hz and 100kHz are optimal for the measuring impedance compare with commercial product used(400Hz and 8kHz)a and there were no differences in accuracy among the three different types of the waveforms; sinusoidal, triangular, and rectangular waves(p>0.05). Impedance ratio of the two different frequencies represents the position of the file in root canal, and the voltage difference of two signals represents the status of the fluid in the root canal. As a result of compensation using the voltage differences, the errors were decreased on the average from +0.54mm to +0.18mm in $H_2O_2$ solution (p<0.01), and from -0.33mm to -0.01mm in NaOCl solution(p<0.01). The accuracies based on ${\pm}$0.5mm, in $H_2O_2$ and NaOCl solutions were improved with the automatic compensation from 71.1% and 91.1% to 82.2% and 100% respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.2
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• pp.85-94
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• 1988

This experiment was carried out to obtain the basic data for removal the astringency and off-flavor in soybean milk, by means of soaking of soybean in NaOH and $NaHCO_3$ solutions. The changes of phenolic compounds in soybean during soaking were investigated with HPLC and also the changes of flavor and sensority of soybean milk, prepared from soaked soybean were studied. Phenolic compounds of soybean were identified as chlorogenic, p-hydroxybenzoic, p-coumaric, ferulic and gentisic acid and, chlorogenic acid content was greater than the others. The chlorogenic acid of soybean was mainly neutral type and the other compounds were almost acidic type. Up to 85% of the chlorogenic acid was removed by soaking of soybean in 0.1% of NaOH solution for 8 hrs. Phenolic compounds of soybean was almost removed by soaking in 0.1% of NaOH solution at $90^{\circ}C$ for 1 hr. Chemical composition of soybean milks prepared from soaking of soybean in water, 0.1% NaOH and 0.5% $NaHCO_3$ solution were similar. Hexanol content of beany flavor in soybean milk was increased by soaking of soybean in NaOH solution, where as hexanal, propanal, pentanal contents were removed up to 60%. Color of soybean prepared from soaking of soybean in NaOH solution at high temperature were deep yellow but were high whiteness in soybean milk prepared from soaking of soybean in water at low temperature. Sensority of soybean milk prepared from soaking of soybean in 0.1% of NaOH solution at $90^{\circ}C$ for 1 hr was more favorable than the others.