• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 춘계 총회 및 학술발표회
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• pp.105-109
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• 1998

1. Introduction : In microfiltration the transport, deposition and removal of particles control cake formation on a filter. In this connection a new model on cake formation, based on the wall shear stress, was tested here in comparison with experiments of fine particle slurry under Taylor-vortex flow. The model expresses the deposition process for particles as two first-order steps in series of mass transfer and adhesion, and their removal process as a linear relation to the wall shear stress. This embraces characteristics of both dead-end and crossflow filtration. The correlation resulting from fitting to experimental data represented the experimental data reasonably well. This study will be helpful in analyzing fouling in heat exchangers.

• 한국막학회:학술대회논문집
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• 한국막학회 1995년도 춘계 총회 및 학술발표회
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• pp.6-10
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• 1995

An inevitable problem feature of membrane processing is concentration polarization (CF) which is a result of the accumulation of retained solutes at the membrane surface. In ultrafiltration (UF), this accumulation can lead to fouling due to the irreversible deposition of macromolecules both at the membrane surface and in the membrane pores. To reduce or control CP and folding, many possible methods have been considered [1]. One of the most effective approaches is to induce fluid instability near the membrane surface by using pusation flow [2, 3], Taylor [4] and Dean [5, 6] vortex flows. Winzeler and Belfort [6] have comprehensively reviewed several possible attempts to use fluid instabihties for improved membrane performance.

• 한국환경과학회지
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• 제25권10호
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• pp.1397-1405
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• 2016

Mussels are stubborn organism attached to solid substrate by byssus threads and caused operational problems in utility of power generating stations. Sole and combined usage of ultrasonic (28 kHz- and 42 kHz- frequencies) and hydrogen peroxide ($H_2O_2$) has studied for control of blue mussel larvae and adult stage in seawater condition. A theoretical wo rking model using disinfection (Chick and Watson type) approaches is presented based on helpful results of experiments. This study also demonstrate that the combined treatment (ultra-sonication with $H_2O_2$) is overall highly efficient than individual treatment would, but on the basis of exposure time, the ultra-sonication was the most efficient among them. Therefore the development of sole and combined technique might be effective practical mitigation strategy against mussel attachment for water handling facilities.

• 멤브레인
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• 제2권2호
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• pp.91-103
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• 1992

Synthetic membrane processes are being increasingly integrated into existing reaction, isolation, and recovery schemes for the production of valuable biological molecules. In many cases they are replacing traditional unit processes. The properties of membrane systems which are most often exploited for both upstream and downstream processing and their permselectivity, high surface area per unit volume, are their potential for controlling the level of contact and/or mixing between two separate phases. Advances in both membrane materials and module design and operation have led to better control of concentration polarization and membrane fouling. After presenting some recent advances in membrane materials and fluid mechanics, we demonstrate how membranes have been integrated into cellular and enzymatic reaction schemes. This is followed by a review of established and emerging synergism between biological processes and synthetic membranes.

• 한국막학회:학술대회논문집
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• 한국막학회 1992년도 추계 총회 및 학술발표회
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• pp.15-33
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• 1992

Synthetic membrane processes are being increasingly integrated into existing reaction, isolation, and recovery schemes for the production of valuable biological molecules. In many cases they are replacing traditional unit processes. The properties of membrane systems which are most often exploited for both upstream and downstream processing are their permselectivity, high surface area per unit volume, and their potential for controlling the level of contact and/or mixing between two separate phases. Advances in both membrane materials and module design and operation have led to better control of concentration polarization and membrane fouling. After presenting some recent advances in membrane materials and fluid mechanics, we demonstrate how membranes have been integrated into cellular and enzymatic reaction schemes. This is followed by a review of established and emerging membrane separation processes. Several examples are used to emphasize the synergism between biological processes and synthetic membranes.

• 에너지공학
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• 제4권1호
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• pp.59-66
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• 1995

본 연구에서는 액체 유동층 열교환기의 수직관내에 유리알 (직경 3.0mm, 비중 2.54) 이 물과 함께 흐를 때 압력 손실, 열전달 계수 및 화울링 계수를 측정하였다. 실험 결과 유리알은 1.0 m/s 이하의 낮은 유속에서 열전달을 증진시켰고 실험범위 내에서 열전달 계수는 유속 및 고체의 흐름양에 관계없이 거의 일정하였다. 압력 손실은 고체의 흐름양이 증가할수록 급격히 증가하였다. 실험 결과를 토대로 압력손실 및 열전달 계수를 예측할 수 있는 상관식을 개발하였다. 유리알 유동층 흐름은 화울링 조절에 효과적인 것으로 일어나지 않았고 이미 화울링이 심하게 일어난 때에도 유리알은 효과적으로 산화철을 제거할 수 있음을 알 수 있었다.

• 상하수도학회지
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• 제19권3호
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• pp.312-317
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• 2005

The 15 month pilot study was performed to investigate the effect of pretreatment by monochloramine ($NH_2Cl$) on the performance of RO membranes made of cellulose acetate (CA) and polyamide (PA). Both RO membranes experienced severe biological fouling without any pretreatment during the treatment of highly organic surface water in Florida, USA. Feed monochloramination at 5 mg/L significantly minimized productivity loss by effective control of biofouling. The CA membrane did not show any structural damages by monochloramine, while the PA membrane suffered from a gradual loss of membrane integrity by chlorine oxidation, which was characterized as an increase in productivity and a decrease in selectivity. The degradation of PA membrane increased with increasing monochloramine dose.

• 한국안전학회지
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• 제29권2호
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• pp.1-6
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• 2014

In this paper, safety certification products and safety condition of small transformer is analyzed in industries field and educational facilities. In transformer of 50places, absolute majority is step down transformer to measure of instrument. Most transformers were below 5kVA and 1~3kVA capacity was the mainstream. In industries field, 5 transformers were found without safety certification according to the Electrical Appliances Safety Control Act as cheap product prefer and lack of safety consciousness. Mark & number, voltage, date of manufacture of safety certification must show item of certification. However date of manufacture showed in product of 18%, 9places. As result of thermal imaging camera, running temperature of transformer was showed in below of target temperature. However as a narrow space of transformer and wall, power cable was touched on a ventilating flue in transformer. It was simple carelessness case that surface fouling and temperature ageing of transformer accelerate. Power poor connection, neglect of transformer in production equipment, fall damage by setup incongruity and ground omission were found in case of illogicality item of transformer.

• Journal of Microbiology
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• 제39권2호
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• pp.133-138
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• 2001

We investigated the antagonism of indigenous bacteria isolated from stressed mussels and their extracellular metabolites on the adult zebra mussel, Dreissena polymorpha. Selective bacterial isolates including Aeromonas media, A. salmonicida, A. veronii, and Shewanella putrefaciens, showed strong lethality against adult mussels and 100% mortality was observed within 5 days of incubation. Bacterial metabolites, fractionated and concentrated from stationary-phase culture supernatants of these bacterial isolates, displayed varying degrees of antagonistic effects on zebra mussels. Among the three size fractions examined, <5, 5-10, and >10 kDa, the mast lethal fraction seems to be >10 kDa for three of the four isolates tested. Further chemical analyses of these size fractions revealed that the predominant constituents were polysaccharides and proteins. No 2-keto-3-deoxyoctanoic acid (2-KDO), deoxyribonucleic acids (DNA) or uranic acid were detectable. Extraction of supernatants of two antagonistic isolates with polar solvent suggested that polar molecules are present in the active fraction. Our data suggest that extracellular metabolites produced by antagonistic bacteria are also involved in disease development in zebra mussels and elucidation of the mechanisms involved may offer a novel strategy for control of biofouling invertebrates.

• Membrane and Water Treatment
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• 제9권4호
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• pp.211-220
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• 2018

Incorporating nano-materials in thin-film composite (TFC) membranes has been considered to be an approach to achieve higher membrane performance in various water treatment processes. This study investigated the rejection efficiency of three target compounds, i.e., reserpine, norfloxacin and tetracycline hydrochloride, by TFC membranes with different graphene oxide proportions. Graphene oxide (GO) was incorporated into the polyamide active layer of a TFC membrane via an interfacial polymerization (IP) reaction. The TFC membranes were characterized with FTIR, FE-SEM, AFM; in addition, the water contact angle measurements as well as the permeation and separation performance were evaluated. The prepared GO-TFC membranes exhibited a much higher flux ($3.11{\pm}0.04L/m2{\cdot}h{\cdot}bar$) than the pristine TFC membranes ($2.12{\pm}0.05L/m2{\cdot}h{\cdot}bar$) without sacrificing their foulant rejection abilities. At the same time, the GO-modified membrane appeared to be less sensitive to pH changes than the pure TFC membrane. A significant improvement in the anti-fouling property of the membrane was observed, which was ascribed to the favorable change in the membrane's hydrophilicity, surface morphology and surface charge through the addition of an appropriate amount of GO. This study predominantly improved the understanding of the different PA/GO membranes and outlined improved industrial applications of such membranes in the future.