• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.373-378
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• 2008

The pH & alkalinity adjustment method by lime and carbon dioxide($CO_2$) for corrosion control in water distribution system was investigated to determine the optimum operational condition in lime adding process in water treatment plant(WTP). The mixing time at dissolution tank and sedimentation time at saturator for maintaining optimal turbidity condition of lime supernatant were 60~75 minutes and 75~95 minutes, respectively. There was no difference according to $CO_2$ adding methods such as $CO_2$ saturated water or $CO_2$ gas. But, $CO_2$ saturated water could be convenience at WTP in terms of pH control and quantitative dosing. To minimize generation of calcium carbonate products, the short time interval between adding of lime and $CO_2$ is most important. The lime should be added below 32 mg/l for preventing pH rising and generation of calcium carbonate products at the heating condition.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1438-1439
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• 2011

In this paper, we studied effects on the efficiency, according to thickness of the electron injection layer(EIL) for improving efficiency of Organic Light Emitting Diodes(OLEDs). For the first time, after confirming the optimum thickness of the EIL material $Cs_2CO_3$, we designed OLED devices having a structure of ITO/TPD/$Alq_3/Cs_2CO_3$/Al. And we manufactured devices applying for the optimum thickness of the material in the simulation with thermal evaporating method. And we investigated how the EIL material $Cs_2CO_3$ effects on efficiency of OLEDs in the EIL. As the result, because the EIL material $Cs_2CO_3$ reduces energy potential barrier of the EIL, it facilitated the electron transfer. And, as blocking the hole transfer contributes to an increased recombination, we confirmed that the efficiency of OLEDs increased. And compared to the device without using the EIL material, the device using thickness 1.0 nm of $Cs_2CO_3$ in the EIL shows the excellent efficiency. Therefore, we confirmed that the luminance and the external quantum efficiency increase about 600% and 500% respectively.

• Clean Technology
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• v.10 no.4
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• pp.215-220
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• 2004

Micronized acetaminophen was precipitated from ethanol solution using supercritical $CO_2$ as antisolvent. A coaxial nozzle was used to introduce the supercritical $CO_2$ and the acetaminophen/ethanol solution. The effects of pressure, temperature, $CO_2$ flow rate and solvent flow rate were studied in the constant pressure and temperature condition. The particle size and morphology were influenced by the variations of precipitation condition. The particle size and morphology were analyzed with scanning electron microscopy.

• Resources Recycling
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• v.25 no.2
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• pp.10-16
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• 2016

In this study, the Ni base superalloy was recycled by Argon oxygen decarburization(AOD) process using an inconel 713C scrap. During AOD process, argon gas was continuously injected 1,000 sccm and oxygen gas was injected into 10, 20 and 30 minutes of 100, 250 and 500 sccm.. In early stage of oxygen injection, the oxygen dose increased with increasing Al, Cr, and Mo content and decreasing C content. And Al content was decreased by carburization with added elements in late stage Because of oxidation was occurred with Al, Cr etc. after the reaction of carbon has been finished. From the results, the ratio of ${\gamma}^{\prime}$ phase reduced due to decreasing of Al content for that reason Al is the main element to form the ${\gamma}^{\prime}$ phase. Also carbide reduced owing to decreasing of C content so the mechanical properties of the specimens excessively injected by excess $O_2$ gas were decreased.

• Geotechnical Engineering
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• v.12 no.3
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• pp.99-108
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• 1996

The physical and chemical properties of polyurethane-yieding twofomponent liquid injection mixture and those of the resulting polyurethane solid foam for chemical grouting are investigated. The chemical experiments on the factors influencing the properties of polyurethane show that the behaviors of polyurethane-yielding liquid material and those of the produced polyurethane solid foam are greatly affected by the ground conditions such as temperature, water content and density of soil. The ground reinforcing and water -blocking effects of polyurethane grouting are examined through field case history of tunnel ericavati on of the subway under construction.

• Korean Journal of Materials Research
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• v.2 no.6
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• pp.417-427
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• 1992

Silicon ion implantation was performed to LPCVD amorphous Si films and the low temperature annealing process followed with various conditions to find the optimal physical properties by studying recrystallization behavior. The uniformity of the recrystallized films was inspected by optical microscopy and for this purpose, new KOH: (IPA) : $H_2$O: $K_2$C${r_2}{O_7}$, etchant was developed. XRD and TEM results showed that the crystallites were grown as a form of dendrite with (111) preferred orientation, and the grain size was increased with dose concentration. The maximum grain size was obtained when the 3${\times}{10^{15}}$c$m^2$ implanted amorphous Si film was recrystallized at 55 $0^{\circ}C$for more than 40 hrs and at this condition the grain size was 3.2${\mu}$m.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.33-36
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• 2005

생활폐기물을 소각한 후 발생되는 바닥재는 토목, 건설 분야에서 골재로서 활용 가치가 높으나, Cu, Pb 등 일부 중금속의 용출량이 환경기준치를 초과하여 바닥재의 재활용을 저해시키는 주요 요인으로 작용하고 있다. 본 연구에서는 바닥재의 중금속 용출을 저감시키기 위한 방법으로서 인위적인 탄산화에 의한 생활폐기물 소각 바닥재의 중금속 안정화 특성을 조사하였다. 4mesh를 기준으로 각 입단에 대해 고액비, 온도, $CO_2(g)$ 주입량에 따라 중금속 용출농도를 조사하였다. 중금속용출시험 결과 Pb, Cr, Cd, As는 미량 또는 불검출되었으며, Cu는 4mesh 이상에서 2.21mg/L, 4mesh이하에서 5.12mg/L로 4mesh이하에서 환경기준치를 초과하였다. 4mesh이하에 대해 탄산화 반응을 수행한 결과 $CO_2(g)$ 주입됨에 따라 pH는 초기 12.5에서 8까지 감소하였으며, Cu의 용출 농도는 pH 10에서 1.34mg/L까지 감소되었으며, pH 9-8에서는 불검출되어 탄산화 반응에 의해 바닥재의 환경적 안정성을 증진시킬 수 있음을 확인할 수 있었다.

• Economic and Environmental Geology
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• v.46 no.1
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• pp.71-84
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• 2013

Most gas hydrates (GH) occur in ocean sediments. Global GH reserves are estimated to be $10^{13}{\sim}20{\times}10^{15}m^3$, which is nearly 1,000 times the amount of current world energy consumption. Methane hydrate (MH) has the potential to be developed into future natural gas resources to replace traditional oil and gas resources, and thus MH production technologies such as depressurization, inhibitor injection, thermal stimulation, and $CO_2-CH_4$ substitution need to be further developed. MH production, which is expected to be in test production until 2014 in Korea, is focused on the development of GH production technologies for use in the commercial production of methane gas. This study compares MH production technology and its ability to meet the twin goals of being both effective and environmentally friendly while taking into consideration the complex phenomena of GH decomposition.

• Membrane Journal
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• v.23 no.5
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• pp.367-374
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• 2013

In the present study, Pebax-2533 plate membranes were prepared by drying precursor solutions which were obtained by dissolving Pebax-2533 polymer in 1-Propanol/n-Butanol mixed solvents. And then the $CO_2$ and $N_2$ permeation behaviors were tested by using a time-lag system. The prepared Pebax-2533 plate membranes showed a considerable $CO_2/N_2$ separation performance : the $CO_2$ permeability was 130 to 288 barr, and the $CO_2/N_2$ permselectivity was 5-8. The $CO_2$ permeation data obtained by varying feed pressure, permeation temperature, and solvent composition announced that not only the $CO_2$ sorption but also the $CO_2$ diffusion is equally important in the overall $CO_2$ permeation.

• Journal of Energy Engineering
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• v.4 no.3
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• pp.372-378
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• 1995

분류층 석탄가스 반응온도에서 slag의 배출 조건을 원활하게 유지하기 위하여 CaCO3를 flux로 사용한 용융특성을 파악하였다. 첨가에 의한 용융온도는 flux 주입량에 따라 감소하다가 증가하였다. 최저 용융온도의 범위는 ash중 CaO 농도기준 30-40%의 범위에서 나타났으며, Base/Acid ratio에 따라 최소 용융온도는 ash중 무기물간의 eutetic effect가 작용함을 알 수 있었다. 고온에서의 slag 조성은 ash의 조성과 비교시 알카리 산화물의 휘발화와 SO2의 감소를 보여주고 있으며, salg중 환원성 가스가 증가함에 따라 금속 산화물의 환원에 의해 SiO2 조성은 증가하였다. CaCO3를 혼합한 시료를 질소분위기하에서 조제하여 점도를 측정한 결과, low silica ash의 경우 낮은 점도치를 보여주나, 250 poise 이하의 범위에서 고화되는 현상이 발생하였다. high silica ash에서는 CaCO3 투입에 의해 slag 점도는 감소하였는데, slag 분석 결과 CaO가 산소 제공물질(oxide doner)로 작용하여 silicate의 응집현상을 억제하는 것으로 나타났다.