• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.238-242
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• 2005

In this work, Polydimethylsiloxane (PDMS) and SU-8 (Microchem, USA) photoresist were used to make the microchannel by soft lithographic method. To investigate the effects of external voltages and widths of the microchannel, we made the microchannel by soft lithographic method. To investigate the effects of external voltages and widths of the microchannel, we made the microchannel with various widths: $100{\mu}m,\;200{\mu}m$ and $300{\mu}m$. And each micorchannel was supplied with external voltage, respectively. As a result, the fluid velocity increased with an increase of the external voltage at the same width. It was speculated that the electrical double layer was condensed and the zeta potential increased with increase of the external voltage. The fluid velocity increased with the microchannel width increase at the same external voltage. It is concluded that the resistance in the microchannel decreased as the microchannel width increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1278-1282
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• 2004

수열처리법으로 nano-sized $CeO_2$ 입자를 $Al_3O_3$ 입자의 표면에 균일하게 코팅하여 $AL_2O_3/O_2$ composite 연마 입자를 제조하었다. 제조된 $Al_2O_3\CeO_2$ composite 입자의 뭍성을 TEM, XRD, zeta potential analyzer 및 particle size analyzer로 측징하였다. $Al_2O_3/CeO_2$ composite 입자와 구성된 슬러리와 비교 시료로서 $Al_2O_3$와 $CeO_2$ 입자를 혼합한 슬러리를 사용하여 thermal oxide film에 대한 연마특성을 평가하였다. 연마슬러리에 포함된 $A1_2O_3/CeO_2$ composite 입자와 $Al_2O_3$와 $CeO_2$ 혼합입자에서 나노 크기의 세리아 입자가 sub-micron 크기의 알루미나 입자의 표면에 균일하게 코팅되므로서 $Al_2O_3$ 단일 성분의 슬러리에 비해 removal rate(RR)는 106 nm/min, WIWNU는 $8\sim9%$, roughness는 $2.6{\AA}$의 향상된 연마 특성을 나타내었다. 알루미나 입자의 불규칙한 형상 때문에 $Al_2O3/CeO_2$ composite 슬러리와 $Al_2O_3$ 와 $CeO_2$ 혼합슬러리의 연마 특성이 비슷한 수준을 나타내었다.

• Membrane and Water Treatment
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• v.9 no.2
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• pp.69-77
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• 2018

The use of membrane as an innovative technology for water treatment process has now widely been accepted and adopted to replace the conventional water treatment process in increasing fresh water production for various domestic and industrial purposes. In this study, ultrafiltration (UF) membranes with different formulation were fabricated via phase inversion method. The membranes were fabricated by varying the polymer concentration (16 wt%, 18 wt%, 20 wt%, and 21 wt%). A series of tests, such as field emission scanning electron microscope (FESEM), pore size and porosity, contact angle, and zeta potential were performed to characterize the membranes. The membrane performance in terms of permeation flux and rejection were evaluated using a laboratory bench-scale test unit with mine water, lake water and tube well as model feed solution. Long hour filtration study of the membranes provides the information on its fouling property. Few pore blocking mechanism models were proposed to examine the behaviour of flux reduction and to estimate the fouling parameters based on different degree of fouling. 21 wt% PVDF membrane with smaller membrane pore size showed an excellent performance for surface water treatment in which the treated water complied with NWQS class II standard.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.591-591
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• 2016

최근에는 재이용을 위한 하 폐수의 처리 공정에 막을 이용한 기술적용이 증가되고 있는 추세이다(현 등, 2005). 막(membrane)을 이용한 수처리 공정은 원수에 상관없이 고도처리가 가능하며, 재이용수 이용 용도에 따른 수질제어가 가능할 뿐만 아니라 운용의 편리성 때문에 많은 각광을 받고 있다(박 등, 2004). 본 연구에서는 하수처리에 이용되는 분리막의 성능을 극대화하고, 분리막의 오염부하를 줄여주기 위하여 분리막 직전 전처리 시설로 부상방식의 고액분리장치를 개발하였다. 초고속 고액분리시스템은 기존의 응집부상공정을 응용한 기술로서 유기물의 응집시간을 최대 10초~2분 이내로 줄이는 기술을 바탕으로 타워형 모듈 형태로 개발하였다. 초고속 고액분리시스템과 분리막을 연계한 재이용수 수처리시스템의 성능 평가 및 현장적용을 위해 제주도 서부 하수 처리장에 일 $3,000m^3$ 규모의 Test-bed를 구축하였다. 구축된 하수재이용시스템의 처리 공정도는 "유입${\rightarrow}$고액분리시스템${\rightarrow}$분리막(UF, RO)${\rightarrow}$농경지 공급"으로 구성되어 있다. 먼저 하수처리장 방류수를 1차 유입조에 압송하면 전처리시설인 고액분리시스템을 통해 SS 등 입자성 물질이 처리되고, 다음 공정인 2차 처리공정(UF/RO)을 통과한 처리수는 인근지역의 농업용수로 공급되고 있다. 고액분리시스템은 ZT(Zeta Potential Tower) 모듈에서 유입수에 함유되어 있는 부유물질(SS), 유기물(질소, 인)을 응집제와 순간 반응시켜 응결, 응집, 부상방식으로 제거하는 공정이다. 고속 고액분리장치는 분리막 공정과 융 복합하여 다양한 유입수 성상에 따른 수처리를 가능하게 하여 재이용수 수질 향상뿐만 아니라 안정된 수자원 확보 측면에서 긍정적인 기술로 평가되었다.

• Food Science of Animal Resources
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• v.39 no.5
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• pp.831-843
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• 2019

The purposes of this research were to form chitosan oligosaccharide (CSO)/A2 ${\beta}$-casein nano-delivery systems (NDSs) and to investigate the effects of production variables, such as CSO concentration levels (0.1%, 0.2%, and 0.3%, w/v) and manufacturing temperature ($5^{\circ}C$, $20^{\circ}C$, and $35^{\circ}C$), on the production and physicochemical characteristics of CSO/A2 ${\beta}$-casein NDSs to carry resveratrol. The morphological characteristics of CSO/A2 ${\beta}$-casein NDSs were assessed by the use of transmission electron microscopy (TEM) and particle size analyzer. High-performance liquid chromatography (HPLC) was applied to determine the entrapment efficiency (EE) of resveratrol. In the TEM images, globular-shaped particles with a diameter from 126 to 266 nm were examined implying that NDSs was successfully formed. As CSO concentration level was increased, the size and zeta-potential values of NDSs were significantly (p<0.05) increased. An increase in manufacturing temperature from $5^{\circ}C$ to $35^{\circ}C$ resulted in a significant (p<0.05) increase in the size and polydispersity index of NDSs. Over 85% of resveratrol was favorably entrapped in CSO/A2 ${\beta}$-casein NDSs. The entrapment efficiency (EE) of resveratrol was significantly (p<0.05) enhanced with an increase in manufacturing temperature while CSO concentration level did not significantly affect EE of resveratrol. There were no significant (p<0.05) changes observed in the size and polydispersity index of NDSs during heat treatments and storage in model milk and yogurt indicating that CSO/A2 ${\beta}$-casein NDSs exhibited excellent physical stability. In conclusion, the CSO concentration level and manufacturing temperature were the crucial determinants affecting the physicochemical characteristics of CSO/A2 ${\beta}$-casein NDSs containing resveratrol.

• Advances in environmental research
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• v.3 no.2
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• pp.107-116
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• 2014

This study aimed to synthesize dispersed and reactive nanoscale zero-valent iron (nZVI) with poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA), nontoxic and biodegradable stabilizer. The nZVI used for the experiments was prepared by reduction of ferric solution in the presence of PVP/VA with specific weight ratios to iron contents. Colloidal stability was investigated based on the rate of sedimentation, hydrodynamic radius and zeta potential measurement. The characteristic time, which demonstrated dispersivity of particles resisting aggregation, increased from 21.2 min (bare nZVI) to 97.8 min with increasing amount of PVP/VA (the ratios of 2). For the most stable nZVI coated by PVP/VA, its reactivity was examined by nitrate reduction in a closed batch system. The pseudo-first-order kinetic rate constants for the nitrate reduction by the nanoparticles with PVP/VA ratios of 0 and 2 were 0.1633 and $0.1395min^{-1}$ respectively. A nitrogen mass balance, established by quantitative analysis of aqueous nitrogen species, showed that the addition of PVP/VA to nZVI can change the reduction capacity of the nanoparticles.

• Journal of the Mineralogical Society of Korea
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• v.31 no.4
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• pp.227-234
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• 2018

In this work, we have prepared the reactive media with the pyrophyllite based using ceramic extrusion process. The characteristics of pyrophyllite were analyzed using XRD, XRF, DSC-TGA and Zeta-potential analysis. The study of pyrophyllite based ceramic reactive media were conducted under various roasting temperature (500 to $1,300^{\circ}C$) conditions. With increasing the roasting temperature, strength was increased but BET surface area was decreased. Thermally treated pyrophyllite were analyzed by means of weight loss and structural changes as detected by using XRD, DSC-TGA and SEM analysis. Pyrophyllite primarily transforms to pyrophyllite dehydroxylate after roasting at $1,000^{\circ}C$. Pyrophyllite dehydroxylate transforms to mullite and cristobalite at $1,300^{\circ}C$. This study demonstrates that pyrophyllite could be used as a reactive media for ceramic support layers from Permeable Reactive Barriers.

• Food Science of Animal Resources
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• v.38 no.6
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• pp.1294-1304
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• 2018

The aims of this research were to examine the effect of heating temperature (65, 75, and $85^{\circ}C$) and $CaCl_2$ concentration level (3, 4, and 5 mM) on the physicochemical properties of ${\beta}$-lactoglobulin (${\beta}$-lg) nanoemulsions (NEs) and to study how the droplet size of NEs affects the bioaccessibility (BA) of coenzyme $Q_{10}$ ($CoQ_{10}$). The droplet size of NEs and BA of $CoQ_{10}$ was assessed by particle size analyzer and UV-Vis spectrophotometer, respectively. An increase in heating temperature and $CaCl_2$ concentration level resulted in a significant (p<0.05) increase in the droplet size of NEs while there were no significant differences in polydispersity index and zeta-potential of NEs. When NEs containing $CoQ_{10}$ were incubated in simulated small intestinal phases, an increase in the droplet size and polydispersity index of NEs was observed. This indicated that NEs were not stable in small intestine and digestion of NEs occurred. As heating temperature and $CaCl_2$ concentration level were decreased, a significant (p<0.05) increase in BA of $CoQ_{10}$ was observed. There was a significant (p<0.05) increase in BA of $CoQ_{10}$ with a decrease in the droplet size of NEs. In conclusion, heating temperature and $CaCl_2$ concentration level were key-parameters affecting the initial droplet size of NEs and BA of $CoQ_{10}$ was negatively correlated with initial droplet size of NEs.

• Advances in nano research
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• v.7 no.4
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• pp.241-248
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• 2019

Recent researches demonstrated well promising anticancer activities for antibiotics. Such effects would be significantly increased while nanoparticle based delivery systems were applied. In this study, the goal was aim to improve anticancer and antitoxic effects of Streptomycin by loading on special kind of dendrimer (anionic-linear-globular second generation). In the current study, Size and zeta potential as well as AFM techniques have been used to prove the fact that the loading was performed correctly. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the drug loaded on dendrimer nanoparticle were determined and compared with both of dendrimer alone and free drug with respect to staphylococcus aureus as the test microorganism. The anticancer activity among three groups including Streptomycin, Streptomycin -G2 dendrimer, and control was measured in vitro. In vitro studies showed that G2 anionic linear-globular polyethylene-glycol-based dendrimer, which loaded on Streptomycin was able to significantly improve the treatment efficacy over clinical Streptomycin alone with respect to proliferation assay. Maximal inhibitory concentration (IC50) was calculated to be $257{\mu}g/mL$ for streptomycin alone and $55{\mu}g/mL$ for Streptomycin -G2 dendrimer. In addition, Streptomycin -G2 dendrimer conjugate prevented the growth of MCF-7 cancerous cells in addition to enhance the number of apoptotic and necrotic cells as demonstrated by an annexin V-fluorescein isothiocyanate assay. Streptomycin -G2 dendrimer conjugate was able to increase Bcl-2/Bax ratio in a large scale compared with the control group and Streptomycin alone. Based on results a new drug formulation based nano-particulate was improved against S. aureus with sustained release and enhanced antibacterial activity as well as anticancer activity shown for functional cancer treatment with low side effects.

• Food Science of Animal Resources
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• v.39 no.2
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• pp.222-228
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• 2019

This research was motivated by our encounter with the situation where an optimization was done based on statistically non-significant models having poor fits. Such a situation took place in a research to optimize manufacturing conditions for improving storage stability of coffee-supplemented milk beverage by using response surface methodology, where two responses are $Y_1$=particle size and $Y_2$=zeta-potential, two factors are $F_1$=speed of primary homogenization (rpm) and $F_2$=concentration of emulsifier (%), and the optimization objective is to simultaneously minimize $Y_1$ and maximize $Y_2$. For response surface analysis, practically, the second-order polynomial model is almost solely used. But, there exists the cases in which the second-order model fails to provide a good fit, to which remedies are seldom known to researchers. Thus, as an alternative to a failed second-order model, we present the heterogeneous third-order model, which can be used when the experimental plan is a two-factor central composite design having -1, 0, and 1 as the coded levels of factors. And, for multi-response optimization, we suggest a modified desirability function technique. Using these two methods, we have obtained statistical models with improved fits and multi-response optimization results with the predictions better than those in the previous research. Our predicted optimum combination of conditions is ($F_1$, $F_2$)=(5,000, 0.295), which is different from the previous combination. This research is expected to help improve the quality of response surface analysis in experimental sciences including food science of animal resources.