• 환경위생공학
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• 제15권3호
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• pp.50-56
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• 2000

In this study, sewage were treated with operating Two-step Aeration System and conventional activated sludge process together in a condition. At the same HRT 8hr of Two-step Aeration System and Activated Sludge Process, BOD treatment efficiency of 1st sedimentation basin effluent 36.9% by Two-step Aeration system was 12.3% higher than 24.65 by Activated Sludge Process and the COD treatment efficiency 39.8% by two-step Aeration System was 11.6.3% higher than 28.2% by Activated Sludge Process. BOD and COD treatment efficiencies of 2nd sedimentation basin effluent were 88.1% and 85.6% Two-step Aeration System and were 83.8% and 82.3% Activated Sludge Process. In the first treatment, as BOD was relatively removed a lot, F/M ratio 0.17, $0.21{\cdot}BOD/kg{\cdot}MLSS.d$ was maintained by Activated Sludge Process. Therefore it was proved that organic matter treatment efficiency by Two-step Aeration System os Higher than by Activated Sludge Process in a aeration time 8hr. $NH_4^{+}-N$ treatment efficiencies were 55.5% by Two-step Aeration System and 39.75 by Activated sludge Process. $NO_3^{-}-N$ concentration in 2nd. sedimentation basin effluent were 3.33% by Two-step Aeration System and 2.36% by Activated Sludge Process. From this result, Two-step Aeration System was proved more advantageous treatment process for nitrification than Activated Sludge Process. The fluctuation range of BOD, COD and SS concentration in 2nd sedimentation basin effluent $16~33mg/{\ell}$, $15~23mg/{\ell}$ and $14~22mg/{\ell}$ by Two-step Aeration System was smaller than $16~57mg/{\ell}$, $15~25mg/{\ell}$ by Activated sludge Process. Overall the fluctuation range in 2nd sediment basin effluent by was smaller than by Activated Sludge Process. As a result, it is possible for this Two-step Aeration with no facility investment and a little of operation condition change in a conventional sewage treatment plant to get stability and nitrification of treatment water quality.

• 한국식품과학회지
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• 제51권6호
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• pp.576-583
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• 2019

본 연구에서는 aeration 공정을 거친 홍삼 추출액의 유효성분 함량을 확인하고 항산화 활성에 미치는 영향을 알아보고자 하였다. Aeration 처리 유무에 따른 추출액의 색상 변화에서는 aeration 공정처리를 하지 않은 추출액과 aeration 공정처리 한 추출액 모두 추출시간이 경과함에 따라서 L값과 b값이 유의적으로 감소하였고, aeration 공정 처리 36시간 추출액에서 명도와 황색도가 가장 낮은 결과를 얻었다. a값은 non-aeration 처리에서는 추출시간이 경과함에 따라서 증가하였으나 aeration 처리할 경우에는 적색도가 감소되는 것을 확인할 수 있었다. 이와 같은 결과는 aeration 공정 처리를 할 경우에는 추출시간이 경과함에 따라 명도, 황색도, 적색도 모두가 감소되면서 갈색도가 증가하는 것을 의미하는 결과라고 할 수 있다. 총 폴리페놀 함량에서 non-aeration 홍삼추출액은 추출시간에 따라 0.62, 0.67, 0.72, 0.79 mg GAE/mL로 나타났으며 aeration 공정을 거친 추출액은 0.62, 0.70, 0.84, 0.96 mg GAE/mL로 추출시간에 따라 유의적으로 크게 증가하는 것을 확인하였다. 또한, 총 플라보노이드 함량은 aeration 공정을 거친 24, 36시간 추출액에서 21.77, 21.93 mg GAE/mL의 최고의 함량을 나타내었다. DPPH 라디칼 소거활성은 non-aeration 홍삼 추출액은 80.50-82.00% 범위에서 확인되었으며 aeration 공정을 거친 홍삼 추출액의 라디칼 소거능은 추출 시간에 따라 82.10, 81.90, 87.30, 87.10%로 나타났다. 이는 DPPH 라디칼 소거활성이 aeration 공정을 거침에 따라 활성이 증가한다는 것을 시사하는 결과이다. ABTS 라디칼 소거능은 24, 36시간에서 non-aeration 추출액이 96.80, 77.60%로 라디칼 소거활성이 떨어졌으나 aeration 공정을 거친 홍삼 추출액은 70.86, 98.60%로 추출 시간에 따라 유의적으로 소거활성이 증가하는 것으로 나타났다. 또한 10, 12, 24, 36시간 동안 aeration 공정을 거친 홍삼 추출액은 65.40, 65.03, 65.61, 63.26%의 hydrogen peroxidase 소거율을 보였고, 또한 0.87, 0.99, 1.04, 0.99로 환원력이 유의적으로 증가하는 것을 확인하였다. 이러한 결과들은 DPPH, ABTS의 경향과 유사하게 aeration 공정을 거침으로서 non-aeration보다 항산화능이 우수하다는 것을 나타냈다. Aeration 공정을 처리한 홍삼추출액으로부터 얻어진 진세노사이드의 함량은 non-aeration과 비교 했을 때 Rg3에서 현저히 차이가 나며, 저분자 진세노사이드 Rg3의 함량이 aeration 공정을 처리한 홍삼추출액에서 166.55, 219.71, 526.67, 581.13 ㎍/mL로 non-aeration 보다 많은 양이 생성되는 것을 확인 할 수 있었다. 이러한 결과들은 aeration 공정을 거친 홍삼추출액이 전반적으로 우수한 항산화 활성을 나타내었으며 향후 특정유효성분을 강화시킬 수 있는 새로운 공정방법으로 활용될 수 있을 것이라 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제13권5호
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• pp.698-701
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• 2000

To prevent surface and underground water pollution, wastewater treatment is essential. Four bench-scale activated sludge units (10 L operational volumes) were operated at 5, 10 and $20^{\circ}C$ for evaluation of treatment efficiencies with typical wastewater from swine housing. The units were set for a 24-hour cycle. As compared to the conventional process, high removal efficiencies for organic substances, nitrogen and phosphorus in swine wastewater were obtained simultaneously with an intermittent aeration process (lAP). The NOx-N produced during an aeration period was immediately reduced to nitrogen gas (e.g. $N_2$ or $N_2O$) in the subsequent non-aeration periods, and nitrification in aeration periods occurred smoothly. Under these conditions, phosphorus removal occurred with the release of phosphorus during the non-aeration periods followed by the excess uptake of phosphorus in the activated sludge during aeration periods. It was confirmed that the lAP had a better ability to remove pollutants under both low temperatures and high nitrogen loading conditions than the ordinary method did. In addition to that, the total emission of $N_2O$ from lAP was reduced to approximately 1/50 of the conventional process for the same loading. By adopting an adequate aeration programme for individual swine wastewater treatment, this system will provide a promising means for nitrogen and phosphorus control without pH control or addition of methanol.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.93-98
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• 2009

The thermophilic aerobic digestion (TAD) process is recognized as an effective method for rapid waste activated sludge (WAS) degradation and the deactivation of pathogenic microorganisms. Yet, high energy costs due to heating and aeration have limited the commercialization of economical TAD processes. Previous research on autothermal thermophilic aerobic digestion (ATAD) has already reduced the heating cost. However, only a few studies have focused on reducing the aeration cost. Therefore, this study applied a two-step aeration control strategy to a fill-and-draw mode semicontinuous TAD process. The NADH-dependent fluorescence was monitored throughout the TAD experiment, and the aeration rate shifted according to the fluorescence intensity. As a result, the simple two-step aeration control operation achieved a 20.3% reduction in the total aeration, while maintaining an effective and stable operation. It is also expected that more savings can be achieved with a further reduction of the lower aeration rate or multisegmentation of the aeration rate.

• Tribology and Lubricants
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• 제17권6호
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• pp.447-452
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• 2001

In development process of engine lubrication system, many failure cases are related with aeration problem. Therefore, it is very important to clarify the aeration in the engine oil circuit system. As of today, many factors have been introduced as the major cause in the engine oil aeration. However, still many test data related with those are required to clearly understand it. In this paper the aeration measurement system and calculation method are introduced. And also using this system we measured engine oil aeration for various cases. From these results some conclusions are reduced.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.171-176
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• 2000

In development process of engine lubrication system, many failure cases are related with aeration problem. Therefore, it is very important to clarify the aeration in the engine oil circuit system. As of today, many factors have been introduced as the major cause in the engine oil aeration. However, still many test data related with those are required to clearly understand it. In this paper the aeration measurement system and calculation method are introduced. And also using this system we measured engine oil aeration fur various cases. From these results some conclusions are reduced.

• Environmental Engineering Research
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• 제19권1호
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• pp.59-66
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• 2014

The aim of this study was to assess the effect of pre-aeration on sludge solubilization and the behaviors of nitrogen, dissolved sulfide, sulfate, and siloxane. The results of this study showed that soluble chemical oxygen demand in sewage sludge could be increased through pre-aeration. The pre-aeration process resulted in a higher methane yield compared to the anaerobic condition (blank). The pre-aeration of sewage sludge, therefore, was shown to be an effective method for enhancing the digestibility of the sewage sludge. In addition, this result confirms that the pre-aeration of sewage sludge prior to its anaerobic digestion accelerates the growth of methanogenic bacteria. Removal rates for $NH_3$-N and T-N increased simultaneously during pre-aeration, indicating simultaneous nitrification and denitrification. The siloxane concentration in sewage sludge decreased by 40% after 96 hr of pre-aeration; in contrast, the sulfide concentration in sewage sludge did not change. Therefore, pre-aeration can be employed as an efficient treatment option to achieve higher methane yield and lower siloxane concentration in sewage sludge. In addition, reduction of nitrogen loading by pre-aeration can reduce operating costs to achieve better effluent water quality in wastewater treatment plant and benefit the anaerobic process by minimizing the toxic effect of ammonia.

• 상하수도학회지
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• 제20권2호
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• pp.257-264
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• 2006

In this study, the treatment of domestic wastewater in a field-scale membrane submerged intermittently aerated activated sludge process($210m^3/day$) was investigated under difference aeration methods. Operating temperature was 5.4 to 25.0 and membrane used in this study is a polyethylene hollow fiber membrane(pore size $0.4{\mu}m$). The range of operating flux was $9.7{\sim}24.4l/m^2-h$ and membrane permeates periodically operated for 7min followed idle for 3 min. The results showed that MIA(modified intermittent aeration) was more efficient in nitrogen and phosphorus removal. The removal efficiencies of T-N and T-P were 73.0% and 69.6% for CIA(conventional intermittent aeration) and 57.5%, 58.6% for MIA (modified intermittent aeration). With application of modified intermittent aeration, DO reached nearly Omg/l within 10 minutes after air off. Organics of influent could be entirely consumed to the denitrification and the P-release without the influence by remained DO in intermittent aeration reactor. Therefore, newly developed KSMBR(Kowaco-KMS-Ssangyoung Membrane Bio-Reactor) process with modified intermittent aeration can be one of the useful process for stable nitrogen and phosphorus removal.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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• pp.777-783
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• 2000

Composting by negative aeration is a reasonable proposition to control odor generated during composting process. Cattle manure and rice hulls mixtures were composted in a bin composting system by negative aeration. Continuous(CA) and intermittent(IA) aeration methods were applied to analyze the composting characteristics. The composting temperature and the ammonia emission during composting were investigated according to the aeration methods. The main problem for the negative aeration was the generation of condensate in the suction line of blower. The quantity of condensate was significant for continuous aeration. The aeration method should be modified to escape from the cooling effect of continuous aeration at the initial stage of composting. It took a longer time to finish a composting for intermittent aeration on account of lower aeration. It was concluded that the composting by negative aeration could be accomplished by either continuous or intermittent aeration method if the flow rate would be controlled more efficiently and the water vapor in suction line of blower could be removed effectively. Ammonia emission increased up to maximum value of 675ppm for continuous aeration while 300ppm for intermittent aeration. However, the cumulative value of ammonia emission was larger for intermittent aeration than for continuous aeration.

• 상하수도학회지
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• 제32권1호
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• pp.11-18
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• 2018

As the sequencing batch reactor process is a time-oriented system, it has advantages of the flexibility in operation for the biological nutrient removal. Because the sequencing batch reactor is operated in a batch system, respiration rate is more sensitive and obvious than in a continuous system. The variation of respiration rate in the process well represented the characteristics of biological reactions, especially nitrification. The respiration rate dropped rapidly and greatly with the completion of nitrification, and the maximum respiration rate of nitrification showed the activity of nitrifiers. This study suggested a strategy to control the aeration of the sequencing batch reactor based on respirometry. Aeration time of the optimal aerobic period required for nitrification was daily adjusted according to the dynamics of respiration rate. The aeration time was mainly correlated with influent nitrogen loadings. The anoxic period was extended through aeration control facilitating a longer endogenous denitrification reaction time. By respirometric aeration control in the sequencing batch reactor, energy saving and process performance improvement could be achieved.