• Tribology and Lubricants
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• 제17권3호
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• pp.198-208
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• 2001

A Parametric study based on a computer analysis of the lubrication system of a four-cylinder gasoline engine is illustrated. Through the parametric study, the effects of various aeration levels on the change of oil flow rate and pressure are investigated. Also, at high oil temperature and low engine speed, the effect of oil aeration level on oil flow characteristics in lubrication system is investigated. The illustrated results may give to designers the guide lines of oil aeration level for the safe design of engine lubrication systems in terms of minimum pressure at crank oil bore.

• 상하수도학회지
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• 제27권1호
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• pp.69-76
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• 2013

Specific growth rate and removal rate of nitrogen and phosphorus of Chlorella sorokiniana, Chlorella vulgaris, Senedesmus dimorphus those are able to metabolite mixotrophically and have high nitrogen and phosphorus removal capacity were examined. Based on the results, one microalgae was selected and conducted experiments to identify the operating factors such as pH and aeration rate. The specific growth rate and phosphorus removal rate of C. sorokiniana significantly presented as $0.29day^{-1}$ and 1.65 mg-P/L/day, while the nitrogen removal rate was high as 12.7 mg-N/L with C. vulgaris. C. sorokiniana was chosen for appropriate microalgae to applying for wastewater treatment system and was cultured in pH ranged 3 to 11. High specific growth rate and removal rate of nitrogen and phosphorus were shown at pH 7 as $0.71day^{-1}$, 7.61 mg-N/L/day, and 1.24 mg-P/L/day, respectively. The specific growth rate examined with aeration rate between 0 and 2 vvm (vol/vol-min) highly presented as $1.2day^{-1}$ with 1.5 ~ 2 vvm, while the nitrogen removal rate was elevated with 0.5 vvm as 9.43 mg-N/L/day.

• 한국환경과학회지
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• 제19권3호
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• pp.371-377
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• 2010

The purpose of this study is to investigate treatment efficiency in dyeing wastewater treatment by the high rate aeration system(HRA) and a combination of the HRA with magnetized wastewater treatment system(MWS). At the hydraulic retention time of 16hr, 24hr, 30hr, BOD removal efficiencies of HRA system were 93%, 96% and 98%, combination of the HRA with MWS system were 94%, 96.8% and 98.2%, respectively. In ease of COD, at the hydraulic retention time of 16hr, 24hr, 30hr, COD removal efficiencies of HRA system were 66%, 77.1% and 83.1%, combination of the HRA with MWS system were 70.2%, 80.1% and 86.6%, respectively. The comparison of the HRA and combination of the HRA with MWS, effluent BOD of the former was 22.7mg/${\ell}$ and the latter was 19.4mg/${\ell}$, theretore biological treatment efficiency identified to increase by the MWS.

• 한국물환경학회지
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• 제29권6호
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• pp.808-812
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• 2013

A new type of microbial fuel cell (MFC) with anaerobic membrane filter was designed to produce bioelectricity and to treat domestic sewage at relatively high organic loading rate (OLR) of $6.25kgCOD/m^3/day$ and short hydraulic retention time (HRT) of 1.9 h. A following aeration system was applied to ensure effluent water quality in continuous operation. Glucose was supplemented to increase the influent concentration of domestic sewage. Influent substrate of 95% was removed via the MFC and following aeration system and the corresponding maximum power density was $25.6mW/m^3$. External resistor of $200{\Omega}$ and air-cathode system contributed better MFC performance comparing to $2000{\Omega}$ and dissolved oxygen as a catholyte.

• 한국미생물·생명공학회지
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• 제22권4호
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• pp.389-394
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• 1994

8 X 10$^{6}$(viable cells/ml) of maximum cell density and 9000(IU/ml) of $\gamma$-IFN production were obtained at 55(ml/hr) of a perfusion rate by cultivating HSF cells using a moving membrane aeration bioreactor. This system proves to be an efficient culture process by maintaning 90% of viable cells during the whole cultivation periods. The metabolic molar quotient of glucose to lactate was 0.81 for overall ranges of glucose consumed while the evolution of ammonia was not linearly related to the consumption of glutamine. Low molar conversion ratio was observed in low consumptions of glutamine and high molar conversion ratio in high comsumptions. It also shows that the glutamolysis plays important role in the steady state conditions by evolving larger quantities of ammonia than lactate. At the above of 50 rpm, which is the optimum agitation speed for this bioreactor, the cell growth was severely affected while the IFN production was less decrea- sed, maintaing 1.5 X 10$^{-3}$(IU/cell/day) specific IFN production rate. The cumulatvie $\gamma$-IFN production was 7.2 X 10$^{8}$(IU) for 70 days of the cultivation, which yields 1 X 10$^{7}$ (IU/day) of IFN production rate. Therefore, a commercial production of $\gamma$-IFN by this culture process can be achievable by maintaining the above IFN productivity in a scaled-up culture system.

• 멤브레인
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• 제26권1호
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• pp.55-61
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• 2016

저압 침지식 멤브레인을 이용한 해수 담수화 전처리에 있어서 유기 파울링은 막간 압력 증가로 인한 화학 세정 횟수의 증가 및 에너지 소비 증가 등 멤브레인 운전시 문제점들을 야기한다. 조류대응 해수전처리에서 조류가 배출하는 extracellular polymeric substances의 대표물질인 sodium alginate를 이용하여 침지식 여과에서 파울링 현상을 관찰하였다. 공기 폭기가 적용되지 않은 경우 순수한 aglinate 파울링은 농도가 증가하면서 증가하였다. 그러나 공기 폭기를 적용해 준 경우 alginate 파울링 감소는 매우 효과적이었다. 공기 폭기가 없는 경우 칼슘 농도의 증가에 따라 alginate 파울링은 감소하였다. 동일 조건에서 공기 폭기 시 높은 alginate 파울링 감소효과를 나타내었으나 NaCl 농도를 증가시킨 경우 칼슘 농도의 증가에 따라 파울링 제어를 위한 공기 폭기 효과는 감소하였다. 해수와 유사한 높은 NaCl과 칼슘 농도에서 고농도 sodium alginate의 경우 공기 폭기량 증가를 통해 초기 파울링을 감소시킬 수 있었으나 시간의 경과에 따라 상대적으로 낮은 폭기량에서의 파울링 감소 효과와 큰 차이는 없었다.

• 상하수도학회지
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• 제25권6호
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• pp.981-987
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• 2011

Biologically treated water contains a large quantity of organic matters and microorganisms which can cause various problems to membrane. The membrane fouling occurred by these reasons is hard to control by single physical cleaning. This study analyzes the efficiency of aeration with chemical backwashing and foulants removal during chemical backwashing. The cleaning efficiency improves when the chemical concentration is high and the contact time of chemical is long. Chemical backwashing with aeration shows exceptional cleaning efficiency which leads the physical cleaning is required during chemical backwashing since it forms flow inside the membrane submerged tank. From the foulants removal analysis, the particles such as turbidity and TOC removal rate increase when the aeration is applied. Dissolved matter of DOC and UV254 removal is dependent on higher chemical concentration. According to FTIR analysis, one of major foulants, the polysaccharide is controlled by the chemical backwashing with aeration condition.

• 동력기계공학회지
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• 제4권3호
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• pp.34-39
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• 2000

Performance data in the literature on air lift pumps have been based primarily on pumps of long length and large diameter (high lift pumps). Since mariculture operations involve pumps of relatively short length and small diameter, performance data are required for efficient operation. To provide such data, an experimental apparatus was designed and fabricated to test all lift pumps from 2.1 to 3.4 cm inside diameter and from 40 to 300 cm in length. Instrumentation was provided to measure water flow rate and air flow rate as well as water temperature, air temperature, and pressure throughout the system. Results from this study correlate well with high lift pump data in that, for a given pump geometry, maximum water flow occurs for a specific air flow rate. Driving the pump with air flows larger or smaller than this optimum flow rate will decrease the pumping rate. The optimum flows are significantly different for low lift pumps compared to high lift pumps. However, the pumping rate for low lift pumps approaches that for high lift pumps with increasing length.

• 멤브레인
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• 제14권4호
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• pp.289-297
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• 2004

유기물과 질소를 동시에 제거하기 위하여 연속회분식으로 운전한 MBR (membrane bioreactor)시스템에서 미생물농도와 슬러지 부하량이 막오염과 미생물 활성에 미치는 영향을 살펴보았다. 막오염은 MLSS (mixed liquor suspended solid) 농도 증가에 따라 조금씩 증가하는 경향을 보였고, 그 효과는 비포기 조건보다 포기 조건에는 좀더 두드러지게 나타났다. MLSS 농도는 막오염에 직접적인 커다란 영향을 주지는 않으나, 지나치게 높은 MLSS에서 유도되는 낮은 슬러지 부하에서는 막오염이 크게 증가하는 현상이 발견되었고, 이러한 조건에서는 포기에 의한 막 세척 효과도 크게 줄어들었다. 미생물의 개별 활성도는 슬러지 부하가 감소할수록 지속적으로 감소하는 경향을 나타내었다 반응조 전체 활성도 또한 17,000 mg/L 이상의 높은 MLSS로부터 유도되는 낮은 슬러지 부하율에서는 높은 미생물 농도에도 불구하고 오히려 감소했는데 이는 기질 부족으로 인한 경쟁으로 활성도가 떨어지고, 용액의 점성 증가로 인해 산소 전달율이 저하되었기 때문이다.

• 한국축산시설환경학회지
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• 제18권sup호
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• pp.13-20
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• 2012

연구는 양돈분뇨의 액비화 처리과정 중 농지환원 직전단계인 액비 후숙처리 단계에 있어서 $SCOD_{Mn}$ 농도 및 산도(pH)의 조정이 후숙액비의 이화학적성상에 미치는 영향을 알아보고 적절한 후숙 액비화 공정을 구축하기 위하여 수행하였으며, 실험결과를 요약하면 다음과 같다. 1. $SCOD_{Mn}$ 감소율은 알칼리발효 처리구에서 평균 29.9%, 인산중성화 처리구에서는 평균 36.9%로 인산 중성화 처리구가 비교적 높은 감소율을 보였다. 2. 30일간 처리 후 $SCOD_{Mn}$의 농도가 가장 낮은 처리구는 유입농도가 가장 낮았던 인산 중성화 처리구 T-6이다. 후숙 액비의 목표수준을 $SCOD_{Mn}$ 3,000 ppm 이하로 가정할 경우 후숙 발효조의 초기 투입농도는 5,500 ppm 이하로 조정하는 것이 적합하다고 사료된다. 3. 질소의 잔존율은 알칼리발효 처리구에서 평균 29.3%, 인산중성화 처리구에서 평균 38.9%로 인산중성화 처리구가 비교적 질소의 손실이 적은 한편, T-P의 경우 인산중성화 처리구에서 높은 농도(평균 1,473 ppm)로 유지되었다. 4. 본 연구를 통해 액비 후숙처리 시 '저인산-저질소'의 형태는 "알칼리발효 처리구", '고인산-고질소'의 형태는 "인산중성화 처리구"의 조건이 유리할 것으로 기대된다.