• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1288-1291
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• 2004

In this study, physical characteristics of alumina slurry on variation of pH value and the effect of non-ionic surfactants on alumina slurry for copper chemical mechanical planarization (CMP) slurry have been investigated. After pH value of the slurry with alumina abrasive was changed by adding various amount of $HNO^3$ or KOH, the differences of settling rate, particle size, and zeta-potential were estimated. Better settling rates were shown in slurries with alumina abrasive at near pH 1. Higher zeta-potential was shown at around pH 2 in alumina slurry and the point of zero charge (PZC) was measured at about pH $9\sim10$. Non-ionic surfactant was added in the slurry with 5wt% alumina abrasive to get its effect on slurry practically. Abrasive size was smaller increased when amount of surfactant increased in slurry with P-4 as abrasive; on the other side, it was smaller when amount of surfactant decreased with AES-12. Variation of zeta-potential has no tendency with adding surfactant; however, values of zeta-potential were between $35\sim50mV$. The proper amount of surfactant was $0.1\sim1.0wt%$ in slurry with P-4 and $0.5\sim1.0wt%$ in slurry with AES-12 respectively. Excellent dispersion stabilization was obtained by addition of non-ionic surfactant

• 한국분말재료학회지
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• 제26권1호
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• pp.6-10
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• 2019

In this study, freeze drying of a porous Ni with unidirectionally aligned pore channels is accomplished by using a NiO powder and camphene. Camphene slurries with NiO content of 5 and 10 vol% are prepared by mixing them with a small amount of dispersant at $50^{\circ}C$. Freezing of a slurry is performed at $-25^{\circ}C$ while the growth direction of the camphene is unidirectionally controlled. Pores are generated subsequently by sublimation of the camphene during drying in air for 48 h. The green bodies are hydrogen-reduced at $400^{\circ}C$ and then sintered at $800^{\circ}C$ and $900^{\circ}C$ for 1 h. X-ray diffraction analysis reveals that the NiO powder is completely converted to the Ni phase without any reaction phases. The sintered samples show large pores that align parallel pores in the camphene growth direction as well as small pores in the internal walls of large pores. The size of large and small pores decreases with increasing powder content from 5 to 10 vol%. The influence of powder content on the pore structure is explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

• Metals and materials international
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• 제24권6호
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• pp.1315-1326
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• 2018

In this work, ultrasonic vibration (UV) and rheo-squeeze casting was first applied on the Mg alloy reinforced with long period stacking ordered (LPSO) structure. The semisolid slurry of Mg-Zn-Y alloy was prepared by UV and processed by rheosqueeze casting in succession. The effects of UV, Zr addition and squeeze pressure on microstructure of semisolid Mg-Zn-Y alloy were studied. The results revealed that the synergic effect of UV and Zr addition generated a finer microstructure than either one alone when preparing the slurries. Rheo-squeeze casting could significantly refine the LPSO structure and ${\alpha}-Mg$ matrix in $Mg_{96.9}Zn_1Y_2Zr_{0.1}$ alloy without changing the phase compositions or the type of LPSO structure. When the squeeze pressure increased from 0 to 400 MPa, the block LPSO structure was completely eliminated and the average thickness of LPSO structure decreased from 9.8 to $4.3{\mu}m$. Under 400 MPa squeeze pressure, the tensile strength and elongation of the rheocast $Mg_{96.9}Zn_1Y_2Zr_{0.1}$ alloy reached the maximum values, which were 234 MPa and 17.6%, respectively, due to its fine ${\alpha}-Mg$ matrix (${\alpha}1-Mg$ and ${\alpha}2-Mg$ grains) and LPSO structure.

• 한국지하수토양환경학회지:지하수토양환경
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• 제28권1호
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• pp.15-24
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• 2023

A persulfate(PS)/sulfidated microscale zero-valent iron(S-mZVI) system was tested for treating a soil contaminated with phenol. Sulfidation of bare mZVI was conducted using a mechanochemical process utilizing a ball mill in order to improve persulfate activation capacity and stability of unmodified mZVI. The synthesized S-mZVI performed markedly better than the bare mZVI in activating PS. The optimum molar ratio of sulfur to mZVI was around 0.12. In the soil slurry experiments, a very rapid and complete removal of phenol was observed at the optimum molar ratios of PS to S-mZVI of 2:1 and PS to phenol of 16:1. The phenol removal efficiencies decreased as the water content of the slurries decreased. This was believed to be due to increased soil oxidant demand as the amount of soil was increased as relative to the water content. To evaluate the field applicability of the process, slurry experiments adopting high soil contents were carried out that simulated in-situ soil mixing conditions. These experiments resulted in substantially compromised degradation efficiencies of 54.3% and 43.8% within 4 hours. The current study generally shows that the PS/S-mZVI process has a potential to be developed into a remediation technology for soils contaminated with organics.

• Geomechanics and Engineering
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• 제29권4호
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• pp.391-405
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• 2022

A newly proposed grouting simulation method, the sequential diffusion solidification method was introduced into the numerical simulation of combined bi-borehole grouting. The traditional, critical and difficult numerical problem for the temporal and spatial variation simulation of the slurry is solved. Thus, numerical simulation of grouting and blocking of flowing water in karst conduits is realized and the mechanism understanding of the combined bi-borehole technology is promoted. The sensitivity analysis of the influence factors of combined bi-borehole grouting was investigated. Through orthogonal experiment, the influences of proximal and distal slurry properties, the initial flow velocity of the conduit and the proximal and distal slurry injection rate on the blocking efficiency are compared. The velocity variation, pressure variation and slurry deposition phenomenon were monitored, and the flow field characteristics and slurry outflow behavior were analyzed. The interaction mechanism between the proximal and distal slurries in the combined bi-borehole grouting is revealed. The results show that, under the orthogonal experiment conditions, the slurry injection rate has the greatest impact on blocking. With a constant slurry injection rate, the blocking efficiency can be increased by more than 30% when using slurry with weak time-dependent viscosity behavior in the distal borehole and slurry with strong time-dependent viscosity behavior in the proximal borehole respectively. According to the results of numerical simulation, the grouting scheme of "intercept the flow from the proximal borehole by quick-setting slurry, and grout cement slurry from the distal borehole" is put forward and successfully applied to the water inflow treatment project of China Resources Cement (Pingnan) Limestone Mine.

• 한국토양비료학회지
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• 제40권4호
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• pp.242-248
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• 2007

돈분뇨 슬러리와 음식물쓰레기 자원화 과정에서 발생하는 액상물의 혼합 액비화를 통한 액비의 비료적 특성 및 액비의 악취 저감 특성을 검토하였다. 발효가 진행됨에 따라 음식물쓰레기 액상물 혼합비율이 높은 처리구에서 pH가 높아졌고 돈분뇨 슬러리 혼합비율이 높은 처리구에서는 낮아졌고, EC는 180일째에 모든 처리구에서 $21{\sim}23dS\;m^{-1}$로 안정되었다. 180일간 발효시키고 난 후에 질소성분은 최초 성분량의 20%까지 저하되었는데, 음식물쓰레기 액상물 50% 이상 혼합한 구에서는 비료공정규격에 미달되었다. 발효가 진행되면서 유기물, 인산, 석회, 고토성분은 감소되었고 칼리, 염분의 함량은 증가하였는데, 염분의 증가는 액비 발효과정 중 수분 증발에 따른 농축효과에 기인하였다. 악취 성분으로서 $NH_3$는 발효 초기 30일째까지 많이 발생하다 점차 감소하였고 돈분뇨 슬러리 혼합비율이 높을수록 오래까지 지속적으로 발생되었고, $R-NH_2$의 경우는 $NH_3$에 비해 발효기간이 길어져도 지속적으로 발생하였다. $C_2H_5SH$는 돈분뇨슬러리와 혼합처리구에서만 발생하였는데, 발효기간 180일이 지나도 지속적으로 발생되었다. 관능검사 결과 역시 돈분뇨슬러리 혼합처리구에서는 발효기간 180 일이 지나도 악취도가 1 이하로 저하되지 않았다. 현행 비료 공정규격상 악취강도 기준이 2 이하인 점과 질소성분의 휘산으로 인한 액비 중 T-N 성분 저하 등을 고려했을 때 이의 제어연구가 수행될 필요가 있었다.

• 자원환경지질
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• 제42권5호
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• pp.413-426
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• 2009

중금속으로 오염된 폐금은광산 주변 논토양에 탄소원을 주입하였을 경우 토착미생물에 의한 중금속의 거동 변화를 실험적으로 확인하고, 미생물학적 황산염환원을 촉진하기 위하여 황산염을 주입하였을 경우의 지구화학적 변화를 관찰하였다. 혐기적 조건에서 오염 토양에 유산염과 포도당 둥의 탄소원을 공급하고 토착미생물을 접종한 후 약 100일 동안 반응시켰으며 반응 시작 후 60일이 경과하였을 때 황산염 250 mg/L를 인위적으로 주입하였다. 유산염을 공급하였을 때 실험 기간 중 pH는 7~8 내외를 유지하였으나 포도당을 공급한 경우에는 초기 24일까지 평균 4.8의 pH를 보이다 이후 7.6까지 증가하였다. 이러한 pH 차이는 포도당을 공급하였을 때 Fe와 대부분의 중금속이 유산염에 비하여 높은 함량으로 용출된 원인으로 판단된다. 실험 초기에 용출된 Fe는 미생물 접종 시료에서 시간에 따라 점진적으로 감소하였다. 용존 Zn, Pb, Ni, Cu의 경우 유산염을 공급하였을 때 미생물을 주입한 시료와 주입하지 않은 비교시료 간에 뚜렷한 함량 차이를 보이지 않았으나, 포도당을 공급하였을 때 약 20일 경과 시부터 Zn, Pb, Ni의 함량이 미생물접종 시료에서 급격하게 감소하였고 Cu는 비교시료보다 높은 용출량을 나타냈다. Cr과 As는 두 탄소원을 공급하였을 때 모두 미생물접종 시료와 비교시료에서 용출이 지속되었으나, 황산염을 주입하자 미생물 시료에서 용존 Cr은 급격히 감소하였고 As는 용출이 중단되었다. 황산염 주입 후 반응 용기에서 검은색 침전물이 형성되었다. 이를 X-선회절분석한 결과 미생물을 주입하였을 때 침전된 물질은 violarite($Fe^{+2}{Ni^{+3}}_2S_4$)로 추정되며 이는 철환원 및 미생물학적 황산염환원에 의하여 침전물이 형성될 때 중금속이 공침전한 것으로 여겨진다. 이상의 결과를 통해 볼 때 논토양에서 용출되기 쉬운 중금속이 미생물학적 황산염환원에 의해 고정화되는 효과를 기대할 수 있다.

• Asian-Australasian Journal of Animal Sciences
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• 제26권2호
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• pp.266-274
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• 2013

The effect of different phytogenic feed additives on reducing odorous compounds in swine was investigated using in vitro fermentation and analyzed their microbial communities. Soybean meal (1%) added with 0.1% different phytogenic feed additives (FA) were in vitro fermented using swine fecal slurries and anaerobically incubated for 12 and 24 h. The phytogenic FAs used were red ginseng barn powder (Panax ginseng C. A. Meyer, FA1), persimmon leaf powder (Diospyros virginiana L., FA2), ginkgo leaf powder (Ginkgo biloba L., FA3), and oregano lippia seed oil extract (Lippia graveolens Kunth, OL, FA4). Total gas production, pH, ammonianitrogen ($NH_3$-N), hydrogen sulfide ($H_2S$), nitrite-nitrogen ($NO_2{^-}$-N), nitrate-nitrogen ($NO_3{^-}$-N), sulfate (${SO_4}^{--}$), volatile fatty acids (VFA) and other metabolites concentration were determined. Microbial communities were also analyzed using 16S rRNA DGGE. Results showed that the pH values on all treatments increased as incubation time became longer except for FA4 where it decreased. Moreover, FA4 incubated for 12 and 24 h was not detected in $NH_3$-N and $H_2S$. Addition of FAs decreased (p<0.05) propionate production but increased (p<0.05) the total VFA production. Ten 16S rRNA DGGE bands were identified which ranged from 96 to 100% identity which were mostly isolated from the intestine. Similarity index showed three clearly different clusters: I (FA2 and FA3), II (Con and FA1), and III (FA4). Dominant bands which were identified closest to Eubacterium limosum (ATCC 8486T), Uncultured bacterium clone PF6641 and Streptococcus lutetiensis (CIP 106849T) were present only in the FA4 treatment group and were not found in other groups. FA4 had a different bacterial diversity compared to control and other treatments and thus explains having lowest odorous compounds. Addition of FA4 to an enriched protein feed source for growing swine may effectively reduce odorous compounds which are typically associated with swine production.

• 한국건축시공학회지
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• 제9권5호
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• pp.71-77
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• 2009

시멘트 혼화용 폴리머 디스퍼션은 시멘트 모르타르 및 콘크리트 내부에서 폴리머 필림을 형성하여 각종 역학적성 질 및 내구성을 향상시킨다. 본 연구는 3종류의 폴리머 디스퍼션을 폴리머 시멘트비 0, 5, 10, 20%로 변환한 폴리머 시멘트 모르타르를 제작, 투수시험을 실시하여 투수성능을 실험하였으며, 더욱이 폴리머 시멘트 슬러리를 폴리머 시멘트 모르타르 표면에 도포하여 방수성능의 개선효과를 평가하였다. 또한 보통시멘트 콘크리트 표면에 폴리머 시멘트 슬러리를 도포하여 시멘트 콘크리트와 폴리머 시멘트 슬러리의 건조수축을 측정하였다. 그리고 기본적인 역학적 성상인 휨강도와 압축강도를 측정하여 보통 시멘트 모르타르와 비교 검토하였다. 연구결과, 폴리머 시멘트 모르타르는 보통 시멘트 모르타르에 비해 방수성능과 강도가 크게 개선되었으며, 폴리머 시멘트 슬러리의 건조수축은 시멘트 콘크리트에 비해 4-5배 크게 나타났다. 또한 향후 건조수축에 따른 접착성능의 영향성에 대한 연구가 진행되어야 할 것이다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.89-91
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• 2000

Polynuclear aromatic hydrocarbon (PAH) compounds are highly carcinogenic chemicals and common groundwater contaminants that are observed to persist in soils. The adherence and slow release of PAHs in soil is an obstacle to remediation and complicates the assessment of cleanup standards and risks. Biological degradation of PAHs in soil has been an area of active research because biological treatment may be less costly than conventional pumping technologies or excavation and thermal treatment. Biological degradation also offers the advantage to transform PAHs into non-toxic products such as biomass and carbon dioxide. Ample evidence exists for aerobic biodegradation of PAHs and many bacteria capable of degrading PAHs have been isolated and characterized. However, the microbial degradation of PAHs in sediments is impaired due to the anaerobic conditions that result from the typically high oxygen demand of the organic material present in the soil, the low solubility of oxygen in water, and the slow mass transfer of oxygen from overlying water to the soil environment. For these reasons, anaerobic microbial degradation technologies could help alleviate sediment PAH contamination and offer significant advantages for cost-efficient in-situ treatment. But very little is known about the potential for anaerobic degradation of PAHs in field soils. The objectives of this research were to assess: (1) the potential for biodegradation of PAH in field aged soils under denitrification conditions, (2) to assess the potential for biodegradation of naphthalene in soil microcosms under denitrifying conditions, and (3) to assess for the existence of microorganisms in field sediments capable of degrading naphthalene via denitrification. Two kinds of soils were used in this research: Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS). Results presented in this seminar indicate possible degradation of PAHs in soil under denitrifying conditions. During the two months of anaerobic degradation, total PAH removal was modest probably due to both the low availability of the PAHs and competition with other more easily degradable sources of carbon in the sediments. For both Harbor Point sediment (HPS-2) and Milwaukee Harbor sediment (MHS), PAH reduction was confined to 3- and 4-ring PAHs. Comparing PAH reductions during two months of aerobic and anaerobic biotreatment of MHS, it was found that extent of PAHreduction for anaerobic treatment was compatible with that for aerobic treatment. Interestingly, removal of PAHs from sediment particle classes (by size and density) followed similar trends for aerobic and anaerobic treatment of MHS. The majority of the PAHs removed during biotreatment came from the clay/silt fraction. In an earlier study it was shown that PAHs associated with the clay/silt fraction in MHS were more available than PAHs associated with coal-derived fraction. Therefore, although total PAH reductions were small, the removal of PAHs from the more easily available sediment fraction (clay/silt) may result in a significant environmental benefit owing to a reduction in total PAH bioavailability. By using naphthalene as a model PAH compound, biodegradation of naphthalene under denitrifying condition was assessed in microcosms containing MHS. Naphthalene spiked into MHS was degraded below detection limit within 20 days with the accompanying reduction of nitrate. With repeated addition of naphthalene and nitrate, naphthalene degradation under nitrate reducing conditions was stable over one month. Nitrite, one of the intermediates of denitrification was detected during the incubation. Also the denitrification activity of the enrichment culture from MHS slurries was verified by monitoring the production of nitrogen gas in solid fluorescence denitrification medium. Microorganisms capable of degrading naphthalene via denitrification were isolated from this enrichment culture.