• Nuclear Engineering and Technology
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• 제16권1호
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• pp.29-35
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• 1984

유리섬유 여과포에 의한 0.1~0.45$\mu\textrm{m}$ 크기의 DOP 부유입자의 제거효율시험을 1~10cm/sec의 유속범위에서 수행하였다. 섬유여과포에 의한 미세입자의 여과는 여과속도에 의하여 결정되는데, 최소제거 효율을 나타내는 DOP 입자의 크기는 여과속도가 증가함에 따라 감소한다. Kuwabara Cell Model과 Von Mises Transformation을 사용하여 유리섬유 여과포내에서 화산에 의한 입자 제거효율을 수치해석적으로 전개하여 구하였으며, 이 계산치는 실험치와 잘 일치하였다. 본 실험의 결과는 여과포의 입자제거효율을 예측하고 최적 운전조건을 추구하는데 기여할 수 있을 것이다.

• 상하수도학회지
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• 제23권6호
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• pp.735-741
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• 2009

This study intends to evaluate the efficiency of non-point source reduction technique by using the porous lightweight and recycled aggregate which microorganism is seeded. In case of infiltration velocity 30~70 mm/hr in high concentration of influent, it is indicated that SS was 40~94%, COD 44~91%, BOD 4~91%, TN 1.2~66%, TP 7~70% of removal efficiency. Removal efficiency is good in infiltration velocity 30 > 50 > 70㎜/hr order. Therefore, the non-point source treatment facility filled with lightweight and recycled aggregate using microbial seeding shows higher removal efficiency than a conventional sand and gravel. We confirm that the function and efficiency are improved significantly and applied to treat non-point sources.

• 소성∙가공
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• 제13권3호
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• pp.225-229
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• 2004

Chemical Mechanical Polishing(CMP) process becomes one of the most important semiconductor processes. But the basic mechanism of CMP still does not established. Slurry fluid dynamics that there is a slurry film between a wafer and a pad and contact mechanics that a wafer and a pad contact directly are the two main studies for CMP. This paper based on the latter one, especially on the abrasion wear model. Material Removal Rate(MRR) is calculated using the trajectory length of every point on a wafer during the process time. Both the rotational velocity of a wafer and a pad and the wafer oscillation velocity which has omitted in other studies are considered. For the purpose of the verification of our simulation, we used the experimental results of S.H.Li et al. The simulation results show that the tendency of the calculated MRR using the relative velocity is very similar to the experimental results and that the oscillation effect on MRR at a real CMP condition is lower than 1.5%, which is higher than the relative velocity effect of wafer, and that the velocity factor. not the velocity itself, should be taken into consideration in the CMP wear model.

• 한국터널지하공간학회 논문집
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• 제14권4호
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• pp.421-435
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• 2012

연마재 워터젯을 이용하여 다양한 영향변수에 따라 암석시편에 굴착(제거)실험을 수행하였다. 현장암반굴착 가능성을 판단하기 위해 신선한 경암(화강암) 시편을 기준으로 수압, 노출시간, 그리고 이격거리에 따라 굴착성능 및 굴착형상을 분석하였다. 특히 이격거리는 현장에서 요구하는 높은 수준의 조건에서 실험을 실시였다. 추가적으로 암석에 따른 굴착성능을 비교하기 위해, 실제 굴착현장에서 획득한 암석시편을 대상으로 P파 속도를 측정하여 동일한 조건에서 워터젯 실험을 수행하였다. 획득된 실험결과로부터 워터젯 변수가 암반제거에 미치는 영향을 분석하였다.

• Ocean and Polar Research
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• 제25권3호
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• pp.269-275
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• 2003

Effects of different operating factors including superficial air velocity (SAV), hydraulic residence time (HRT), protein concentration, and foam overflow height on protein removal by a foam fractionator in simulated seawater aquaculture system were investigated. This experiment was conducted on batch and consecutive modes at different combinations of the affecting factors. The foam fractionator had a diameter of 20cm and a height of 120cm and the experiment was conducted with synthetic wastewater. In 5 consecutive trials, protein concentrations in culture tank water decreased faster when the foam fractionator was operated at higher SAVs and lower HRTs. In batch trials, protein removal rates increased with an increase in SAV but decreased with an increase in URT. Higher protein concentrations in the bulk solution resulted in higher protein removal rates. Protein concentrations in the collected foam condensates increased but the foam overflow rates decreased with the increase of foam overflow heights. The results of this experiment indicate that foam fractionation would be an effective way for protein removal in seawater aquaculture systems and the performance of the foam fractionator depends largely on the operating parameters, especially SAV.

• 한국대기환경학회지
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• 제14권6호
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• pp.599-606
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• 1998

Removal of toluene vapor from airstreams was studied in a biological reactor known as a biofilter. The biofilter was packed porous ceramic inoculated with thickened activated sludge (MLVSS 17,683 mg/L). The lab-scale biofilter was operated for 42 days under various experimental conditions including inlet toluene concentrations and flow rates of the contaminated air streams. Removal efficiency reached up 96.6% after 4 days from start up. Nutrient limitation was proposed as a reason for the decrease in biofilter performence. Biofilter performance decreased substantially, coincident with the buildup of back pressure due to accumulation of excess VSS within the medium bed. Practically, the bed needs to be backwashed when the overall pressure drop is greater than 460.6 Pa at SV (Space Velocity) 100 h-1. Periodic backwashing of the biofilter was necessary for removing excess biomass and attaining stable long -term high removal efficiency The removal efficiency of toluene in the biofilter decreased as the gas velocity and toluene concentration in the inlet gas increased. The maximum elimination capacity of ceramic biofilter could reach up to 444.85 g/m3. hr. When the loading of toluene exceed this critical value, substrate inhibition occurred.

• 상하수도학회지
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• 제30권6호
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• pp.663-671
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• 2016

Coagulation/precipitation process has been widely used for the removal of phosphate within domestic wastewater. Although Fe and Al are typical coagulants used for phosphate removal, these have some shortages such as color problem and low sedimentation velocity. In this study, both Fe and Al were used to overcome the shortages caused by using single one, and anionic polymer coagulant was additionally used to enhance sedimentation velocity of the precipitate formed. Batch experiments using a jar test were conducted with real wastewater, which was an effluent of the second sedimentation tank in domestic wastewater treatment plant. Response Surface Methodology was used to examine the responsibility of each parameter on phosphate removal as well as to optimize the dosage of the three coagulants. Economic analysis was also done on the basis of selling prices of the coagulants in the field. Phosphate removal efficiency of Fe(III) was 30% higher than those of Fe(II). Considering chemical price, optimum dosage for achieving residual phosphate concentration below 0.2 mg/L were determined to be 18.14 mg/L of Fe(III), 2.60 mg/L of Al, and 1.64 mg/L of polymer coagulant.

• 한국대기환경학회지
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• 제26권3호
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• pp.330-338
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• 2010

In this study, removal characteristics of nitrogen oxides $(NO_x)$ from road transport by using peat as the packing media for biodegradation have been investigated in the long term. Physicochemical and biological treatment of peatmixed media eliminates any requirement to use chemical substances and also facilitates the biodegradable actions of microorganism. Safe biodegradation of pollutants, no need to apply additional microbes owing to their active growth, and no generation of secondary pollutants were found in this experiment. It was concluded that average removal efficiencies of nitric oxide (NO) and nitrogen dioxide $(NO_2)$ were 80% and 97% respectively with respect to the linear velocity 35~40 mm/s and 0.3 ppm ozone concentration in the long period operation. Inflow concentration of nitric oxide over 0.05 ppm was suitable when pretreated with ozone. Non-ozone stage was performed with linear velocity 20~100 mm/s and then the average removal efficiency of nitric oxide and nitrogen dioxide were 38% and 94% respectively. Other results showed that the apparent static pressure was raised with increases in applied water content and aerial velocity in mixed media during fan operation.

• Ecology and Resilient Infrastructure
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• 제6권4호
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• pp.208-216
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• 2019

본 연구는 하천 내의 자연형 수질정화기법으로 박층류 하도의 설계방법과 효율에 대해서 연구하였다. 박층류 하도의 설계인자를 고려하여 설계를 수행하고 오산천 고수부지에 시험구간을 조성하여 모니터링을 수행하였다. 수위, 유속, 유량, T-N, T-P, NO₃-N 등에 대한 모니터링 결과를 이용하여 제거효율을 평가하고 설계식을 제시하였다. T-N, T-P, NO₃-N 등의 제거효율은 10 - 20%로 나타났으며 체류시간과 일정한 관계를 나타내고 있다. 또한 조류 형성과 유속 간의 관계를 통해 최소 유속 조건을 제시하였다. 본 연구에서 제시된 체류시간과 제거효율의 관계식은 차집수로 설계와 운영에 유용할 것으로 기대된다.

• 한국수산과학회지
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• 제30권3호
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• pp.334-339
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• 1997

포말 분리법에 의한 양어장 순환수 중의 고형물 제거 특성을 조사하였다. 장치의 효율에 영향을 미치는 주요인자들은 공탑 공기유속, 체류시간, 그리고 포말층의 높이였다. 측정된 양어장수 시료 내에는 총 단백질량의 약 $50\%$정도가 계면 활성 성분이었다. 공탑 공기유속, 체류시간이 증가함에 따라 단백질, T-N. TA 및 고형물 성분들의 제거율은 증가하였으며, TVS의 제저율은 공탑 공기유속 및 체류시간 (HRT)이 증가함에 따라 증가하였으나 포말층 높이가 높아짐에 따라서는 감소하였다. 포말분리장치는 양어장 순환수 중에서 발생되는 어류 성장에 유해한 성분, 특히 TA 및 TVS의 제거에 우수한 성능을 보임을 알 수 있었다.