• 제목/요약/키워드: Removal mechanism

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Experimental and Numerical Analysis of A Novel Ceria Based Abrasive Slurry for Interlayer Dielectric Chemical Mechanical Planarization

  • Zhuanga, Yun;Borucki, Leonard;Philipossian, Ara;Dien, Eric;Ennahali, Mohamed;Michel, George;Laborie, Bernard;Zhuang, Yun;Keswani, Manish;Rosales-Yeomans, Daniel;Lee, Hyo-Sang;Philipossian, Ara
    • Transactions on Electrical and Electronic Materials
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    • v.8 no.2
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    • pp.53-57
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    • 2007
  • In this study, a novel slurry containing ceria as the abrasive particles was analyzed in terms of its frictional, thermal and kinetic attributes for interlayer dielectric (ILD) CMP application. The novel slurry was used to polish 200-mm blanket ILD wafers on an $IC1000_{TM}$ K-groove pad with in-situ conditioning. Polishing pressures ranged from 1 to 5 PSI and the sliding velocity ranged from 0.5 to 1.5 m/s. Shear force and pad temperature were measured in real time during the polishing process. The frictional analysis indicated that boundary lubrication was the dominant tribological mechanism. The measured average pad leading edge temperature increased from 26.4 to $38.4\;^{\circ}C$ with the increase in polishing power. The ILD removal rate also increased with the polishing power, ranging from 400 to 4000 A/min. The ILD removal rate deviated from Prestonian behavior at the highest $p{\times}V$ polishing condition and exhibited a strong correlation with the measured average pad leading edge temperature. A modified two-step Langmuir-Hinshelwood kinetic model was used to simulate the ILD removal rate. In this model, transient flash heating temperature is assumed to dominate the chemical reaction temperature. The model successfully captured the variable removal rate behavior at the highest $p{\times}V$ polishing condition and indicates that the polishing process was mechanical limited in the low $p{\times}V$ polishing region and became chemically and mechanically balanced with increasing polishing power.

Experimental study of Nutrient Removal by Endogeneous Nitrate Respiration (ENR) Mechanism in domestic wastewater (질산성질소의 내생탈질기작을 이용한 하수내 영양소 제거에 관한 실험적 연구)

  • Park, Myung-Gyun;Ahn, Won-Sik;Lee, Eui-Sin;Heo, Yong-Rok;Park, Chong-Bok
    • Clean Technology
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    • v.8 no.2
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    • pp.77-83
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    • 2002
  • The purpose of this study is to develop the efficient nutrient removal process and to verify operation and design parameters in domestic sewage. Endogenous nitrate respiration (ENR) was used for denitrification of nitrate in return sludge without additional organic carbon source. ENR reactor before the anaerobic tank enable to reduce nitrate below 3 mg/L and increase phosphate release at anaerobic reaction. Primary effluent during pilot scale plant were shown as TCOD/TP ratio of 40~60 and TCOD/TKN ratio of 5~7. Effluent concentrations were 10 to 12mg/L as TN and 1mg/L as TP respectively. In lab scale experiments endogenous denitrification rate of ENR reactor ranges from 0.042 to $0.057gNO_3-N/gMv.d.$ $SP_{rel}/SCOD_{rm}$ was shown as from 0.13 to 0.17 in anaerobic reaction. These kinetic parameters are expected to be available for BNR(Biological Nutrient Removal) plant design and ENR reaction is available for nutrient removal in low strength wastewater.

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Effect of NADH-Dependent Enzymes Related to Oxygen Metabolism on Elimination of Oxygen-Stress of Bifidobacteria (NADH요구 산소대사관련 효소가 bifidobacteria의 산소스트레스 제거에 미치는 영향)

  • Ahn, Jun-Bae;Park, Jong-Hyun
    • Korean Journal of Food Science and Technology
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    • v.37 no.6
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    • pp.951-956
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    • 2005
  • Selection of oxygen-tolerant strains and elucidation of their oxygen tolerance mechanism were crucial for effective use of bifidobacteria. Oxygen-tolerant bifidobacteria were able to significantly remove environmental oxygen (oxygen removal activity) as compared to oxygen-sensitive strains. Most oxygen removal activity was inhibited by heat treatment and exposure to extreme pH (2.0) of bifidobacterial cell. NADH oxidase was major enzyme related to oxygen removal activity. Oxygen-tolerant bifidobacteria possessed high NADH peroxidase activity level to detoxify $H_2O_2$ formed from reaction of NADH oxidase. Addition of oxygen to anaerobic culture broth significantly increased activities of HADH oxidase and NADH peroxidase within 1hr and rapid increment of oxygen concentration was prevented. Results showed NADH oxidase and NADH peroxidase of oxygen-tolerant bifidobacteria played important roles in elimination of oxygen and oxygen metabolite $(H_2O_2)$.

Mechanism of Removal of Cr(VI) Ions from Solution by Borosilicate Glasses Containing Alkaline Earth Oxides (알칼리토 금속산화물이 함유된 붕규산염계 유리를 이용한 용액 중 Cr6+ 이온 제거 기구)

  • Back, Il-Hee;Lim, Hyung-Bong;Kim, Cheol-Young
    • Journal of the Korean Ceramic Society
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    • v.48 no.3
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    • pp.222-227
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    • 2011
  • The hexavalent chromium ions in wastewater are highly toxic chemicals even at low concentrations. It causes serious diseases, such as cancer, skin disease, digestive trouble et. al. In this study, $Cr^{6+}$ ions were removed by using borosilicate glasses. Various glasses system with different compositions were prepared and then reacted in a solution contaning $Cr^{6+}$ ions. After the reaction, the concentration of the $Cr^{6+}$ ions remained in the solution was measured by ICP-OES. The reacted surface of the glasses was also analyzed by using a XRD, SEM, and EDS. When $Na_2O-RO-SiO_2-B_2O_3$ (RO=MgO, CaO, SrO, BaO) glasses were reacted with a solution containing $Cr^{6+}$ ions, the optimum removal efficiency of $Cr^{6+}$ ions was observed in the BaO glass. $Ba^{2+}$ ions leached out of these glasses combine with $Cr^{6+}$ ions in a solution to form $BaCrO_4$ crystals on the glass surface. In this manner, the $Cr^{6+}$ ions can be removed from the solution. It is conceivable that $Ba^{2+}$ ions are reacted with $Cr^{6+}$ ions in a solution immedeately after leaching out of the glasses. The pH of the solution for optimum removal of $Cr^{6+}$ ions were 3.0~5.0.

Cu2+ ion reduction in wastewater over RDF-derived char

  • Lee, Hyung Won;Park, Rae-su;Park, Sung Hoon;Jung, Sang-Chul;Jeon, Jong-Ki;Kim, Sang Chai;Chung, Jin Do;Choi, Won Geun;Park, Young-Kwon
    • Carbon letters
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    • v.18
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    • pp.49-55
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    • 2016
  • Refuse-derived fuel (RDF) produced using municipal solid waste was pyrolyzed to produce RDF char. For the first time, the RDF char was used to remove aqueous copper, a representative heavy metal water pollutant. Activation of the RDF char using steam and KOH treatments was performed to change the specific surface area, pore volume, and the metal cation quantity of the char. N2 sorption, Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), and Fourier transform infrared spectroscopy were used to characterize the char. The optimum pH for copper removal was shown to be 5.5, and the steam-treated char displayed the best copper removal capability. Ion exchange between copper ions and alkali/alkaline metal cations was the most important mechanism of copper removal by RDF char, followed by adsorption on functional groups existing on the char surface. The copper adsorption behavior was represented well by a pseudo-second-order kinetics model and the Langmuir isotherm. The maximum copper removal capacity was determined to be 38.17 mg/g, which is larger than those of other low-cost char adsorbents reported previously.

Removal Mechanisms for Water Pollutant in Constructed Wetlands: Review Paper (인공습지에서 오염물질 제거기작 및 국내외 연구동향)

  • Ko, Dae-Hyun;Chung, Yun-Chul;Seo, Seong-Cheol
    • Journal of Korean Society of Environmental Engineers
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    • v.32 no.4
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    • pp.379-392
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    • 2010
  • In these days, constructed wetlands are applied in Korea for various purposes ; post-treatment of effluent in wastewater treatment, management of stormwater and restoration of aquatic ecosystems. However, the removal mechanisms for water pollutant in constructed wetlands are not clearly understood because they are affected by climate, influent characteristics and local constraints. Therefore, this paper is focused on the process that the pollutant, especially nitrogen and phosphorus, of the wetland is removed by. In this study, the main nitrogen removal is performed by nitrification/denitrification mechanism in the rhizosphere of constructed wetlands. And the majority of the phosphorus is removed by adsorption on the substrate of wetland. However the fate of phosphorus in wetlands can be diverse depending on the Oxidation Reduction Potential(ORP), adsorption/desorption, precipitation/dissolution, microbial effect, etc.

Comparison of Pollutants Removal between the Intermittently Aerated Bioreactor(IABR) and Intermittently Aerated Membrane Bioreactor(IAMBR) (간헐포기공정과 막결합 간헐포기공정의 오염물질 제거특성 비교)

  • Choi, Chang Gyoo;Lee, Kwang Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1B
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    • pp.119-124
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    • 2006
  • The purpose of this study was the comparison of pollutants removal and the track study of the nitrogen and phosphorus, the estimation of the nitrification and denitrification rate, and the investigation of the nitrogen mass balance between intermittently aerated membrane bioreactor(IAMBR) and intermittently aerated bioreactor(IABR), thus it verified the validity of the membrane submergence. As a result, it had no difference of organic matter removal, however, IAMBR showed better efficiency than IABR in the nutrients. Also, $NO_3{^-}$-N concentration at the anoxic state in the reactor was lower in IAMBR, and the denitrified nitrogen of IAMBR was 40.9%, that of IABR was 10.7%, thus it found out that the denitrification capability of IAMBR was higher than IABR above fourfold. Therefore, it seems resonable to conclude that the membrane helps to improve the removal of pollutants, because of the high MLSS concentration and the available method of intermittent inflow/outflow.

Cochlin-cleaved LCCL is a dual-armed regulator of the innate immune response in the cochlea during inflammation

  • Rhyu, Hyeong-Jun;Bae, Seong Hoon;Jung, Jinsei;Hyun, Young-Min
    • BMB Reports
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    • v.53 no.9
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    • pp.449-452
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    • 2020
  • The inner ear is a complex and delicate structure composed of the cochlea and the vestibular system. To maintain normal auditory function, strict homeostasis of the inner ear is needed. A proper immune response against infection, thus, is crucial. Also, since excessive immune reaction can easily damage the normal architecture within the inner ear, the immune response should be fine regulated. The exact mechanism how the inner ear's immune response, specifically the innate immunity, is regulated was unknown. Recently, we reported a protein selectively localized in the inner ear during bacterial infection, named cochlin, as a possible mediator of such regulation. In this review, the immunological function of cochlin and the mechanism behind its role within inner ear immunity is summarized. Cochlin regulates innate immunity by physically entrapping pathogens within scala tympani and recruiting innate immune cells. Such mechanism enables efficient removal of pathogen while preserving the normal inner ear structure from inflammatory damage.

Effect of sodium on transmembrane calcium movement in the cat ileal longitudinal muscle

  • Rho, Young-Jae;Yun, Il;Kang, Jung-Sook
    • Archives of Pharmacal Research
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    • v.10 no.2
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    • pp.80-87
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    • 1987
  • To get a better insight into the exxistence and the role of a Na-Ca exchange mechanism in smooth muscle, the effect of Na substitution with sucrose on tension development, cellular Ca uptake and $^{45}Ca$ efflux was investigated using isolated cat ileal longitudinal muscle strips. Experimental results were summarized as follows;1) Exposure of the cat ileal longitudinal muscle to Na-free solution induced a contraction, and the magnitude of the contraction increased after incubation of the muscle strips with ouabain ($2{\times10^{-}5}$M) for 1hr. 2) Cellular Ca uptake in Na-free solution increased with an increase in Na content of the Na-loading media, and a linear relationship existed between tissue Na content and cellular Ca uptake for 10 min 3) After tissues were equilibrated in PSS containing $^{45}Ca$ for 2hr, cellular Ca uptake decreased with rising the external Na concentration. 4)Removal of medium Na or inhibition of the Na-K pump decreased the rate of $^{45}Ca$ efflux. These results strongly suggested that Na substitution increases cellular Ca uptake and decreases the rate of $^{45}Ca$ efflux via a Na-Ca exchange mechanism.

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Electroconvective Instability on Undulated Ion-selective Surface (파상형 이온 선택 표면상의 전기와류 불안정성)

  • Lee, Hyomin
    • Korean Chemical Engineering Research
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    • v.57 no.5
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    • pp.735-742
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    • 2019
  • In this work, the electrokinetic interactions between the undulated structure of an ion-selective membrane and electroconvective instability has been studied using numerical analysis. Using finite element method, electric field-ionic species transport-flow field were analyzed by fully-coupled manner. Through the numerical study, the Dukhin's mode as the mechanism of undulated surface for the electroconvective instability were proven. The Dukhin's mode which competes with Rubinstein's mode has roles of (i) decreasing transition voltage to overlimiting regime and (ii) non-linearly increasing of overlimiting current. Also, (iii) the mixing efficiency is enhanced by removal mechanism of high-frequency Fourier mode of the electroconvective instability. Conclusively, the undulated ion-selective surface would provide energy-efficient mechanism for ion-selective transport systems such as electrodialysis, electrochemical battery, etc.