• Membrane Journal
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• v.12 no.1
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• pp.41-50
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• 2002

The streaming potential generated by the electrokinetic flow within electric double layer of charged microchannel is applied to determine the zeta potential of hollow-fiber membrane pore by using the general Helmholtz-Smoluchowski equation. The streaming potential is know to provide a useful real-time information on the surface property and the interaction between pore and particles in actual situations and physicochemical conditions. The influence of physicochemical parameters upon the filtration with hollow-fibers has been examined with an in-situ and simultaneously monitoring the streaming potential as well as permeate flux. In particular, the present study examined an experimental method to identify the effect of cake layer which can vary according to the axial position of a hollow-fiber and the progress of membrane fouling by measuring the position-dependent streaming potential. As the latex concentration increases, the permeate flux decreased but the streaming potential increased. The growth of cake layer has been mire developed with increasing latex concentration, however, the effect of surface charges of latexes deposited on the membrane surface leads to increase the streaming potential. With increasing ionic concentration of KCI, both the permeate flux and the streaming potential decrease. The increase of ionic concentration provides a compact cake layer due to the shrinkage of Debye length and the decreased streaming potential results from the weakened ionic flows owing to a thin diffusive double layer.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.27-29
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• 2009

본 연구에서는 Titanate Nanotube (TNT)를 LBL-SA (layer-by-layer self-assembling) method을 이용하여 전기변색 (electrochromism device, ECD) 소자에 적용하고자 하였다. TNT 분말은 10M NaOH와 $TiO_2$를 혼합한 후 autoclave에서 130$^{\circ}C$, 48시간 동안 수열합성하여 제조하였다. 주사전자현미경 (SEM)으로 TNT 분말의 형상을 관찰한 결과, 직경 20$\sim$30nm, 길이 500$\sim$600nm의 튜브 형상을 나타내었으며, X-선 회절시험 (XRD) 결과 층상구조로 확인되었다. 코팅 물질의 표면 전하를 이용한 LBL-SA method에 적용시키기 위해 수용액 중에서 TNT 입자 표면 전하를 TBAOH (tetrabutylammonium hydroxide)를 적정하여 제타 전위 값이 -40mV로 최대가 되도록 하였으며, 이때 pH 값은 9로 나타났다. 2전극 시스템을 이용하여 cycle voltammetry를 측정한 결과, -0.5$\sim$-1.5V 영역에서 산화환원전위 피크가 뚜렷하게 나타났으며, 짙은 갈색으로 변색되는 것을 확인하였다. 본 연구 결과로서 TNT 박막은 전기를 인가하였을 때 n-type 반도체 성질을 갖는 것으로 나타났으며, 앞으로 display 연구 분야에 적용할 수 있을 것으로 주목된다.

• Journal of the Korean Ceramic Society
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• v.39 no.1
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• pp.38-44
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• 2002

Dispersion stability of nano-sized rutile TiO$_2$powder with acicular typed primary particle produced by homogeneous precipitation process at low temperatures was studied in aqueous and non-aqueous media in the presence of various electrolytes. The zeta potential measurements have shown that the addition of electrolytes to aqueous and non-aqueous dispersion media leads to charge reversal on TiO$_2$particle surface. The electrostatic repulsive forces acting on between TiO$_2$particles dispersed in non-aqueous media were found to be significantly greater than that in aqueous media, which relate closely to the physical properties of the organic solvents, such as viscosities and dielectric constants. The pH values, the concentration of electrolytes and the valence of the ions have changed greatly the surface potential of TiO$_2$ particles and have governed the dispersion behavior of TiO$_2$particles virtually.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.890-893
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• 2001

Zeta potential measurement not only can provide surface information on colloidal biomaterials but more importantly can be used in bioprocess control and products quality control. In this study, zeta potentials for intracrystalline proteins of each layers from oyster shell prepared in 1mM NaCl at different pH were measured. Also, in forming calcite crystals with intracrystalline proteins as an additive extracted from oyster shell, the zeta potentials were measured. These studies were performed to verify the primary role of intracrystalline proteins in controlling the formation, morphological development and crystallography of the biocomposite.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.5
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• pp.1098-1107
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• 2001

This study is to develop the pretreatment for the excess and digested sludge by elector-coagulation and dewatering. Electrocoagulation is applied to excess and digested sludge before transferring to the pistion type for dewatering. Piston type filter press as a laboratory scale plant was used to estimate the dewaterability. MMD of excess sludge was increased from initial diameter of particles ($34.16{\mu}m$) to the 87%($64.01{\mu}m$) after electrocoagulation. Al electrode is more effective than Fe electrode for the dewaterabiltity of excess sludge Electrodewatering after electrocoagulation as pretreatment makes the water content of sludge cake 50~60 wt%.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1992-1997
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• 2003

This study is to develop the pretreatment for the excess and digested sludge by electro-coagulation and dewatering. Electrocoagulation is applied to excess and digested sludge before transferring to the piston type press for dewatering. Piston type filter press as a laboratory scale plant was used to estimate the dewaterability. MMD of excess sludge was increased from initial diameter of particles(34.16 ${\mu}m$) to the 87%(64.01 ${\mu}m$) after electrocoagulation. AI electrode is more effective than Fe electrode for the dewaterability of excess sludge. Electrodewatering after electrocoagulation as pretreatment makes the water content of sludge cake $50{\sim}60$ wt%.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.59-62
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• 2007

The basic concept and preliminary performance results of a miniaturized electroosmotic (EO) pump with diaphragms were included in the present study. The separation of an electroosmotic pumping liquid from a drug using diaphragms is mainly to have a freedom in choosing an electroosmotic pumping liquid and to achieve the optimal drug delivery, and, preferably its precise control. We performed maximum flow rate, maximum pressure, and maximum current measurements with and without diaphragm designs. As a result, the effect of diaphragms on pump performance at the maximum condition is small. However, the presence of diaphragms does not allow indefinite continuous pumping.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.689-696
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• 2008

In a water treatment process a complete and homogeneous dispersion of the coagulants in the raw water could be most important factor. This research was performed to evaluate coagulation performance of the in-line-orifice mixer which was recently introduced as a rapid mixing device. The test was to determine the actual coagulant dispersion distribution on the overall cross-section at a distance of 1.6~3D from the chemical injection point by measuring zeta potential. From the results of zeta potential test, it was shown that the coagulant dispersion within the in-line orifice mixer was occurred very unevenly. The results have confirmed that it is necessary to increase the velocity of coagulants injection or pressurized water rates, in order to reduce nonuniform distribution of chemicals.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.247-253
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• 2004

Major species of Lake Deganuma has varied depending on the season. Namely, there are Micractinium pusillum, chlorella., Scenedesmus sp. shown up in spring season, Microcystis aeruginosa, Microcystis wesenbergii, Anabena spiroides in summer and autumn season and Cyclostephanos invisitatus, Diatoma in winter season in the Lake. As the number of plankton increased, the zeta potential on their surface of them decreased. For this reason, they were dispersed in the lake though the population increased. Zeta potential of M. aeruginosa showed -20mV when their outer size got smaller. As for coagulant dosing in DAF, large amount of coagulant was effective to get lots of sludge during water treatment.

• Journal of the Mineralogical Society of Korea
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• v.7 no.2
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• pp.91-96
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• 1994

중.저준위 방사성 폐기물의 대표적인 핵종인 137Cs, 90Sr에 대한 캐올리나이트의 흡착특성을 수용액의 이온강도와 pH의 영양하에서 알아보았다. 흡착실험은 회분식으로 하였고, 사용한 수용액은 NaCl, CaCl2, MgSO4, KCL 각각을 10-1, 10-2, 10-3, 10-4 mole/$\ell$로 하였다. 수용액광물 평형상태의 pH를 4.5, 7.0, 10.5로 조절하였다. 실험결과 캐올리나이트의 Cs, Sr 흡착은 이온강도와 pH에 상당한 영향을 받으며, Sr 흡차에 양이온들의 경쟁은 Ca2+ Mg2+>K+>Na+ 순을 보이고, Cs의 경우에는 K+>Ca2+ Mg2+>Na+의 순을 보인다. 이는 수용액상에서 이온들의 수호에너지와 관련되며, 광물입자와 이온들의 물구조변환특성에 의해 설명된다. Cs과 Sr 사이에 흡착우선성은 산성 내지 약알카리에서는 Cs이 Sr보다 흡착이 잘 되나, 강알칼리성 환경에서는 Sr이 Cs보다 흡착이 잘 되는 pH 의존성을 보였다. 수용액의 pH가 증가함에 따라 핵종의 흡착량이 증가하는데, 이는 캐올리나이트의 흡착자리인 실라놀과 알루미놀에 의한 제타전위가 pH에 의존함과 잘 일치한다.