• 상하수도학회지
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• 제18권5호
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• pp.666-672
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• 2004

Granular media filtration is used almost universally as the last particle removal process in conventional water treatment plants. Therefore, superb particle removal efficiency is needed during this process to ensure a high quality of drinking water. However, every particle can not be removed during granular media filtration. Besides the pattern of particle attachment is different depending on physicochemical aspects of particles and suspension. Filtration experiments were performed in a laboratory-scale filter using spherical glass beads with a diameter of 0.55 mm as collectors. A single type of particle suspension (Min-U-Sil 5) and pH control was used to destabilize particles. The operating conditions were similar to those of standard media filtration practice: a filtration velocity of 5 m/h. More favorable particles, i.e., particles with smaller surface charge, were well attached to the collectors especially during the early stage of filtration. This selective attachment of the lower charged particles caused the zeta potential distribution (ZPD) of the effluent to move to a more negative range. On the other hand, the ZPD of the effluent did not keep moving from less negative to more negative during the later stages of filtration, and this result was thought to be caused by two reasons: ripening effects and the detachment of flocs.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 Proceedings of the 4th Korea-China Joint Workshop on Nuclear Waste Management
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• pp.12-27
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• 2004

Pretreatment process consisted of submerged hollow-fiber microfiltration(HMF) membrane and spiral-wound nanofiltration(SNF) membrane has been developed by NETEC, KHNP for the purpose of improving the impurities of liquid radioactive waste before entering Selective Ion Exchange System(SIES). The lab-scale combined system was installed at Kori NPP #2 nuclear power plant and demonstration tests using actual liquid radioactive waste were carried out to verify the performance of the combined system. The submerged HMF membrane was adopted for removal of suspended solid in liquid radioactive waste and the SNF membrane was used for removal of particulate radioisotope such as, Ag-l10m and oily waste because ion exchange resin can not remove particulate radioisotopes. The liquid waste in Waste Holdup Tank (WHT) was processed with HMF and SNF membrane, and SIES. The initial SS concentration and total activity of actual waste were 38,000ppb and $1.534{\times}10_{-3}{\mu}Ci/cc$, respectively. The SS concentration and total activity of permeate were 30ppb and lower than LLD(Lower Limit of Detection), respectively.

• 대한의용생체공학회:의공학회지
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• 제15권3호
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• pp.259-264
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• 1994

혈액으로부터 헤파린을 선택적으로 제거하기 위하여 cellulose 기질에 양이온 고분자인 poly(allylamine)(PALA)을 새로운 방법으로 고정화하여 헤파린 제거제를 제조한 다음 in vitro 헤파린 용액내에서 흡착실험을 행하여, 미처리 cellulose control과의 흡착능을 비교하였다. 제조된 헤파린 제거제와 미처리 cellulose의 표면적은 각각 1.36 및 $2.56m^2$/g로 개질처리된 경우의 표면적이 약 1/2로 감소하였다. 또한 제조된 헤파린 제거제에 흡착된 헤파린의 양은 개질 방법에 따라 0.16~$0.03{\mu} g$/$cm^2$로 미처리 celluose($0.03{\mu} g$/$cm^2$)보다 월등히 우수한 헤파린 흡착능을 나타내었다.

• 자원리싸이클링
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• 제27권5호
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• pp.54-60
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• 2018

철 스크랩으로부터 제조되는 철강재의 품질은 재활용 스크랩 중의 미량원소에 의해 악영향을 받는다. 특히 철 스크랩 중의 Cu는 소량이라도 그 영향이 크기 때문에 주의하여야 하는 원소이다. 본 연구에서는 철 스크랩 중의 Cu를 염소가스에 의해 선택적으로 제거할 수 있는 가능성에 대해서 실험실적으로 검토하였다. Cu를 함유하는 모의 철 스크랩을 여러 가지 분위기의 염소가스와 반응시켰다. 실험결과 Cu는 염화되어 증발되었으나, Fe는 염소와 산소의 혼합가스 분위기에서는 표면만 산화되고 염화되지 않았다.

• 한국분무공학회지
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• 제21권2호
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• pp.71-77
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• 2016

Air pollutants nitrogen oxides are inevitably generated in the combustion reaction. Its amount trend is steadily increasing because the rapid modern industrialization and population growth. For this reason, NOx is controlled to reducing the harmful components in the exhaust gas. So Marine Environment Protection Committee (MEPC) take effect 'Tier I', 'Tier II' of air pollution regulation in 2005 and 2011 respectively. According to NOx emissions are strictly regulated management of the vessel through them. In addition, since 2016 the regulation enter into force in the next step 'Tier III' was confirmed by MEPC 66th committee. It's 80% enhanced emissions limits than the 'Tier I' Alternatively these emission regulation, research is actively being carried out about exhaust gas after-treatment methods through the vessel application of Selective Catalytic Reduction(SCR). Therefore depending on the basic specification of cell density according to the Area velocity, Space velocity, Linear velocity is studied the effects of NOx removal efficiency

• 전기화학회지
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• 제20권1호
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• pp.1-6
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• 2017

본 연구에서는 구리 배선 공정에서 구리 씨앗층 표면에 형성되는 구리 자연산화물을 제거하는 표면 전처리가 후속 구리 전착에 미치는 영향을 살펴보았다. 구리 배선 공정의 화학적 기계적 연마 공정에서 사용하는 citric acid 기반의 용액을 구리 표면 전처리 과정에 적용하여 표면에 존재하는 구리 자연 산화물을 제거하였고, 용액 조성 변화를 통해 산화물 제거의 선택성을 높여 구리 씨앗층의 손실을 최소화하였다. 또한 표면 전처리 후 구리 전해 전착과 무전해 전착을 시도하여 전착한 박막의 비저항, 표면 거칠기 등의 성질을 비교하고, 이를 통해 선택적으로 구리 산화물을 제거한 이후에 전착된 박막의 비저항과 표면 거칠기가 가장 낮게 나타남을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제26권2호
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• pp.281-284
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• 2005

The Fe/MgO catalysts with different Fe loadings (1, 4, 6, 15 and 30 wt% Fe) were prepared by a wet impregnation with iron nitrate as precursor. All of the catalysts were characterized by BET surface analyzer, X-ray diffraction (XRD), temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The maximum removal capacity of $H_2S$ was obtained with 15 wt% Fe/MgO catalyst which had the highest BET surface area among the measured catalysts. XRD of Fe/MgO catalysts showed that well dispersed Fe particles could be present on Fe/MgO with Fe loadings below 15 wt%. The crystallites of bulk $\alpha$-$Fe_2O_3$ became evident on 30 wt% Fe/MgO, which were confirmed by XRD. TPR profiles showed that the reducibility of Fe/MgO was strongly related to the loaded amounts of Fe on MgO support. Therefore, the highest removal efficiency of $H_2S$ in wet oxidation could be ascribed to a good dispersion and high reducibility of Fe/MgO catalyst. XPS studies indicated that the $H_2S$ oxidation with Fe/MgO could proceed via the redox mechanism ($Fe^{3+}\;{\leftrightarrow}\;Fe^{2+}$).

• 한국전기전자재료학회논문지
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• 제14권3호
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• pp.175-184
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• 2001

In this study, the improved throughput and stability in device fabrication could be obtained by applying CMP process to STi structue in 0.18 um semiconductor device. To employ the CMP process in STI structure, the Reverse Moat Process used to be added after STI Fill, as a result, the process became more complex and the defect were seriously increased than they had been,. Removal rate of each thin film in STI CMP was not uniform, so, the device must have been affected. That is, in case of excessive CMP, the damage on the active area was occurred, and in the case of insufficient CMP nitride remaining was happened on that area. Both of them deteriorated device characteristics. As a solution to these problems, the development of slurry having high removal rate and high oxide to nitride selectivity has been studied. The process using this slurry afford low defect levels, improved yield, and a simplified process flow. In this study, we evaluated the 'High Selectivity Slurry' to do a global planarization without reverse moat step, and also we evaluated EPD(Eend Point Detection) system with which 'in-situ end point detection' is possible.

• The Plant Pathology Journal
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• 제19권6호
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• pp.280-283
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• 2003

A soybean-sprout rot epidemic occurred in a mass production soybean sprout factory in 2000 and 2001 in Korea, which caused up to 20% production loss. Among the causal pathogenic bacteria and fungi, Pythium deliense was found to be the dominant pathogen of severe root and hypocotyls rot, particularly in recirculating water system. An average of 90% of the isolated fungi from the rotted sprout on potato dextrose agar were Pythium sp. The fungal density of Pythium in the sampled water was monitored in the recycled water system for 1 year using a selective medium (com meal agar with Pimaricin, 10 mg； Rifampicin, 10 mg； and Ampicillin, 100 mg per 1 liter). The drained water from the soybean-sprout cultivation always had a certain amount of fungus in it. The removal of Pythium from the recycling water system must be thorough, safe, and environment friendly. However, the pathogen in the water was easily found even after ozone and chlorine treatments, which were devised on the recycling system for the removal of microorganisms. 5-$\mu\textrm{m}$ pore size filter was applied and was able to successfully control the disease. As the sprout industry increasingly shifts into mass production, the demand for water will increase continuously. Recycling water for sprout production is eco-friendly. However, a process must be devised to be able to first decompose organic matters before Pythium zoospores are filtered.

• Environmental Engineering Research
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• 제10권1호
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• pp.38-44
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• 2005

Electro-thermal production of white phosphorus(WP, P4) generates substantial amount of highly toxic phossy water and sludges. Because of their high phosphorus contents and lack of reliable processing technology, large tonnages of these hazardous wastes have accumulated from current and past operations in the United States. In this study, two different methods for treatment of phosphorus sludge were investigated. These were bulk removal of WP by physical separation(froth flotation) and transformation of WP to oxyphosphorus compounds by air oxidation in the sludge medium. Kerosene, among other collectors, resulted in selective flotation of WP from the associated mineral gangue. Solvent action of kerosene occurring on the WP surface(by rendering WP particles hydrophobic) might produce the high selectivity of WP. The WP recovery in the froth was 79.3% from a sludge assaying 34.2% of WP. In the oxidation study, air gas was dispersed in the sludge medium by the rapid rotation of the impeller blades. The high level of sludge agitation intensity caused a fast completion of the oxidation reactions and it resulted in the high percentage conversion of WP to PO4-3 with PO3-3 making up almost all portion of oxyphosphorus compounds. The WP analysis on the treated sludge showed that supernatant solution and solid residue contained an average of 4.2 μg/L and 143 ppm respectively from the sludge containing about 26 g of WP. Further investigation will be required on operational factors to better understand the processes and achieve an optimum condition.