• 한국환경과학회지
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• 제29권6호
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• pp.623-631
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• 2020

This study analyzes the effect of negative air ions on the concentration of airborne particulate matter and evaluates the expected purification efficiency of open spaces for particulate matter by investigating the amount of negative air ions generated by plants. This study establishes a negative air ion generation treatment environment, plant environment, and control environment to measure the purification efficiency of particulate matter under the conditions of each, analyzing the expected purification efficiency by designing a particulate matter purification model. Results show that the amount of generated negative air ion according to environment was negative air ion generation treatment environment > plant environment > control environment; this order also applies to the particulate matter purification efficiency. Moreover, it took 65 min for the negative ion generation treatment environment, 90 min for the plant environment, and 240 min for the control environment to reach the standard expected purification efficiency of particulate matter concentration of 960 mg/㎥ for PM₁₀. For PM_2.5, with the designated maximum concentration of 700 mg/㎥, it took 60 min for the negative ion generation treatment environment, 80 min for the plant environment, and more than 240 min for the control environment. Based on these results, the expected purification efficiency compared to the control environment was quadrupled in the negative ion generation treatment environment and tripled in the plant environment on average.

• 한국환경보건학회지
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• 제23권1호
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• pp.50-54
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• 1997

The removal efficiency of nutrient was investicated by using Glycine max Meer seedling. After budding, Glycine max Merr was raised at darkness for 4 days. During cultivation, the removal efficiency of $NO_2-N+NO_3-N$ was up to 90% with initial concentration of 20-100 ppm. The removal efficiency of PO$_4$-P was up to 80% with initial concentration at 30 ppm, but it was down to 22% and 27% at 40 ppm and 50 ppm. When the removal efficiency of nutrient was compared with alternating 12 hours' light and darkness, the removal efficiency of NO$_2$-N + NO$_3$-N was up to 90% at below 60 ppm. It was not different from each other. But it was particularly low about 62% and 34% at 80 ppm and 100 ppm in alternating 12 hours' light. The removal efficiency of PO$_4$-P was low at alternating 12 hours' light between 10-50 ppm on the whole range. The neutralizing capacity of pH was shown in acidity and alkalinity except strong acidity(below pH 3). The initial pH was neutralized at 6.0-7.7 of pH after 4 days. Particularly, Glycine max Meer seedling that was difference from other water plants, was shown the neutralizing capacity in strong alkalinity.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.93-96
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• 2009

In the cathode channel of a PEM fuel cell, the local concentration of oxygen near the gas diffusion layer (GDL) decreases in streamwise direction due to chemical reactions, which degrades the efficiency of the oxygen consumption and overall fuel cell efficiency. We numerically studied the influence of the swirling flow generated by a slanted groove mixer (SGM) on the concentration distribution of oxygen. We found that the swirling flow can increase the concentration of oxygen near the GDL, and subsequently improves the oxygen consumption rate.

• 환경위생공학
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• 제17권2호
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• pp.40-47
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• 2002

In this study, water hyacinth plants(Eichhornia crassipes), water parsley(Oenanthe javanica) and Lemna paucicostate were used to treat contaminants such as COD, T-N and T-P in far m·fishing village wastewater. The results were as follows : In the batch system experiment, water hyacinth was showed at the high removal efficiency in the 173∼412kgCOD/ha·day concentration that is rather than 260mg/1 of the high concentration. The next is Oenanthe javanica, Lemna. Oenanthe javanica was showed the high removal efficiency in the 96∼173kgCOD/ha·day concentration that is less than 260mg/1 of the low concentration.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.437-438
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• 2008

박막태양전지에서 p-layer, i-layer, n-layer의 thickness와 doping concentration은 가장 기본이 되는 요소이다. 각 layer에서 위 두 가지 요소를 ASA simulator를 이용해서 높은 효율을 갖는 박막태양전지를 설계하기 위해 조절하였다. Simulation결과 p-layer의 thickness는 $9.5*10^{-9}m$, doping concentration은 0.2eV, i-layer의 thickness는 $4.535*10^{-7}m$, n-layer의 thickness는 $2*10^{-8}m$, doping concentration 은 0.1eV에서 최종 11.48%의 효율을 얻을 수 있었다. 본 연구를 통하여 높은 효율의 박막태양전지 설계 시에 도움이 될 수 있을 것이다.

• 한국분무공학회지
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• 제18권2호
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• pp.81-86
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• 2013

To comply with the regulation of the reinforcing Clean Air Conservation Act, it is necessary for the semiconductor manufacturers to develop effective low-concentration acid gas abatement system to treat the flue gas. The low-concentration acid gas was found to be harder to deal with than the high-concentration one. In this study, the effect of various potential treatments such as air-assist nozzle spraying, magnetizing the scrubbing water, and adding surfactants to spraying and scrubbing water were investigate through the application of the statistical ANCOVA method, which was proved to be very useful tool when the inlet concentration of acid gas could not be controlled precisely and it affected the removal efficiency of the abatement system.

• 환경위생공학
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• 제11권3호
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• pp.13-19
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• 1996

Packed bed reactor containing immobilized microorganisms which degraded phenol without growth was used to remove phenol from the synthetic wastewater. The effects of temperature, retention time(reactor volume/flow rate) and phenol concentration on the removal efficiency of phenol were investigated. The effect of temperature in the range of 20-30$\circ $C was negligible while retention time and phenol concentration influenced the removal of phenol significantly. When retention time was in the range of 1-1.5 hour, the removal efficiency of phenol was affected not by phenol concentration but by retention time itself while it was influenced by phenol concentration above 1.5 hour of retention time. The beads after 720 hours operation were swelled by 40 % in diameter which could be prevented by crosslinking with glutaraldehyde at the expense of cell activity.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2001년도 Proceedings of the 3rd Annual Meeting of Yellow Sea Environment
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• pp.64-69
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• 2001

The present work provides a result from the preliminary experiment for hydrocyclone technology. In this work, local lake sediments and waste coal fly ash were used as test samples, prior to the application of hydrocyclone technology to the waste sludge thickening. A few cyclones based on the Rietema standard geometry were prepared. Chemical analysis of the sediments showed that more organic contaminants were in smaller particles. The experimental tests further showed that physical characteristics of particles, configuration of the cyclone and operation condition would affect the separation efficiency. The current results showed that small size cyclones might improve the separation and concentration of the lake sediments, and higher inlet velocity would increase the concentration rate of under flow and absolute concentration of sediment particles.

• 한국응용과학기술학회지
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• 제37권2호
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• pp.214-223
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• 2020

본 연구는 L-alanine을 적용한 스크러버의 주류공장 내 CO₂ 제거효율, 모니터링 데이터 분석/평가 및 에너지 저감효율을 평가하였다. 스크러버의 평균 제거율은 90.45%로 10,000 ppm이상의 고농도 CO₂가 유입됨에도 제거효율이 뛰어난 것을 확인하였다. 스크러버 작동 후 작업장 내 CO₂는 2,000ppm 이하로 유지하여 약 74% 이상의 이산화탄소 저감 효율을 확인하였다. 또한 소비되는 전력량을 측정한 결과 스크러버 작동 후 230 kWh로 약 7.26%의 에너지가 절감되는 것으로 나타났다. 즉, 본 개발제품을 적용한 결과로 작업장 내 이산화탄소 농도를 외기유입 없이 낮은 농도로 유지함에 따라 근무자의 작업환경을 개선시킬 수 있었으며 에너지 소비량 또한 저감할 수 있었다. 그러므로 식품, 주류공장 내 고농도 CO₂ 제거 공정으로써 스크러버가 유용할 것으로 기대된다.

• 한국환경과학회지
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• 제26권1호
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• pp.23-28
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• 2017

This study was aimed at determining the changes in heavy metal removal efficiency at different acid concentrations in a micro-nanobubble soil washing system and pickling process that is used to dispose of heavy metals. For this purpose, the initial and final heavy metal concentrations were measured to calculate the heavy metal removal efficiency 5, 10, 20, 30, 60, and 120 min into the experiment. Soil contaminated by heavy metals and extracted from 0~15 cm below the surface of a vehicle junkyard in the city of U was used in the experiment. The extracted soil was air-dried for 24 h, after which a No. 10 (2 mm) was used as a filter to remove large particles and other substances from the soil as well as to even out the samples. As for the operating conditions, the air inflow rate in the micro-nano bubble soil washing system was fixed at 2 L/min,; with the concentration of hydrogen peroxide being adjusted to 5%, 10%, or 15%. The treatment lasted 120 min. The results showed that when the concentration of hydrogen peroxide was 5%, the efficiency of Zn removal was 27.4%, whereas those of Ni and Pb were 28.7% and 22.8%, respectively. When the concentration of hydrogen peroxide was 10%, the efficiency of Zn removal was 38.7%, whereas those of Ni and Pb were 42.6% and 28.6%, respectively. When the concentration of hydrogen peroxide was 15%, the efficiency of Zn removal was 49.7%, whereas those of Ni and Pb were 57.1% and 42.6%, respectively. Therefore, the efficiency of removal of all three heavy metals was the highest when the hydrogen peroxide concentration was 15%.