• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.20-20
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• 1994

오일폐액처리에 있어서 한외여과막을 이용하는 기술은 이미 산업분야에서 성공적으로 적용되고 있다. 그러나 오일폐액처리에 있어서 농도분극 및 겔층 (Gal layer) 형성에 의한 플럭스 감소와 막의 수명 단축은 해결해야할 중요한 숙제로 남아있다. 이와같은 문제제기로부터 본 연구에서는 한외여과막에 의한 오일처리에서 공기를 유입함으로써 플럭스를 향상시켰고, 긍극적으로 막에 의한 수용성 오일 처리 기술의 경제적 효율을 높이는 방법을 연구하였다. 수용성 오일의 막 분리는 일반적으로 농도에 따른 플럭스의 변화가 Gel Polarization Model을 따르는 것으로 보고 있다. 즉 오일의 농도가 농축됨에 따라 플럭스가 급격히 감소하여 어느 농도이상 농축시키기 위해서는 비경제적인 운영을 해야만 한다. 본 연구에서는 플럭스를 향상시키기 위해 오일 용액내로 공기를 유입시켰다. 절삭유 용액속에는 에멀젼을 안정화 시키기 위한 계면활성제가 포함되어 있어 공기를 유입할 경우 용액의 상이 액체에서 거품과 액체와의 혼합상으로 변하게 된다. 이러한 상의 변화로 인해 농도에 따른 플럭스가 Gel Polarization Model을 따르지 않고 농도에 따른 감소가 현저히 둔화됨을 관찰하였다.

• Membrane Journal
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• v.18 no.4
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• pp.354-361
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• 2008

Effects of operational conditions and solution chemistry on permeate flux in a hybrid ozone-ceramic ultra-filtration (UF) membrane system treating natural organic matter (NOM) were investigated. Results showed that the extent of permeate flux decline was higher at higher cross-flow velocity and ozone dosage, but it was higher at lower transmembrane pressure (TMP). The mechanism of fouling mitigation was found to be more dependent upon reaction between ozone and natural organic matter at/near catalytic membrane surface than scouring effect due to ozone gas bubbles. Addition of calcium into model NOM solution at high pH led to significant decline in permeate flux while the calcium effect on permeate flux decline was less pronounced at lower pH. After permeate flux decline during the early stage of filtration, the flux started recovering and approached fully to the initial value of it due to degradation of NOM by catalytic ozonation at ceramic membrane surface in the hybrid ozone-ceramic membrane system.

• Food Science and Preservation
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• v.6 no.4
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• pp.424-428
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• 1999

The performance of a 30K polysulfone membrane for clarification of depectinized peach juice was studied Ultrafiltration of peach juice could minimize to loss of flavor and many compounds and was expected to effectively remove precipitation and suspended solid. The results showed that permeate flux increased with the increase of operating pressure and temperature. The permeate flux declined continuously as the process time increased. The values of soluble solid and titratable acidity of permeate were decreased or were at the same level, the turbidity was largely decreased. Total resistance decreased with lower temperature and lower pressure.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.124.2-124.2
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• 2012

위성체의 전위는 위성 주변의 우주 환경에 크게 영향을 받는다. 본 연구에서는 과학기술위성 1호(STSAT-1)에 탑재된 LP(Langmuir Probe)와 ESA(Electro-Static Analyzer) 관측 자료를 이용하여 위성체의 전위에 위성 주변 고에너지 입자들이 미치는 영향을 분석하였다. 일반적으로 위성체가 대전되어 위성체의 부동전위가 감소할 때 위성 주변의 플라즈마 밀도는 감소하고 온도는 증가한다. 또한 DMSP 위성 등을 비롯한 이전 관측에서는 고에너지 입자의 플럭스가 증가하는 지역을 위성이 통과할 때 위성체의 전위가 감소하였다. 본 연구에서는 위성이 수 ~ 수 십 keV 정도의 고에너지 입자 플럭스가 증가한 후 감소하는 지역을 통과할 때에도 위성체의 전위가 감소하는 현상을 관측하였다. 고에너지 입자의 플럭스가 감소하는 지역에서 일어나는 위성의 대전현상을 통계적으로 분석해 보고 이러한 결과를 토대로 위성체 전위 변화에 우주환경 변화가 어떤 영향을 주는지 연구하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.486-486
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• 2012

반도체 식각 공정에서 이온의 플럭스와 충돌 에너지를 각각 조절하고자 Dual frequency RF source가 사용된다. 듀얼 freuqnecy RF가 인가된 Capacitively coupled plasma (CCP) 의 경우, 기판에 걸린 Low freuqency (LF) RF 소스에 의하여 이온의 에너지를 조절하고, High frequency (HF) 소스를 조절하여 이온의 플럭스를 조절하는 것이 일반적이다. 그러나 LF의 세기가 증가함에 따라서, 플라즈마의 밀도가 오히려 감소하는 문제점이 있었다. 이 경우, 약한 자장을 플라즈마에 걸어줌으로써 밀도가 감소되는 문제를 해결할 수 있다고 알려져 왔다. Inductively coupled plasma (ICP) 에서는 HF를 안테나에 가하여 이온의 플럭스를 조절하고, LF를 기판에 가하여 이온의 충돌 에너지를 조절하는 것이 일반적인데, 위와 동일한 문제가 이 경우에도 발생하는 것을 확인 하였다. CCP와 마찬가지로, 바이어스에 걸린 파워의 세기가 증가함에 따라서 플라즈마의 밀도가 감소하고 전자의 온도가 증가하는 현상을 확인하였다. 또한 이때에도, 약한 자장을 걸어줌으로써 플라즈마의 밀도가 감소하지 않고 유지될 수 있으며, 전자의 온도 또한 유지될 수 있음을 발견하였다.

• Clean Technology
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• v.7 no.3
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• pp.195-202
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• 2001

In this study the trace of chlorinated organic compound in aqueous solution was separated by pervaporation process using crosslinked PDMS (polydimethylsiloxane) membrane. The flux of trichloroethylene(TCE) increased linearly with feed composition but the flux of water was slightly increased. The partial flux of TCE was greater than that of tetrachloroethylene(PCE). The partial flux of TCE was not changed with operating temperature, but increased rapidly with feed flow rates. High crosslinking density causes the reduction of solubility and diffusivity for target component. The reduction of flux and selectivity for TCE is due to the chain immobilization and reduction of diffusivity with crosslinking density.

• Journal of Astronomy and Space Sciences
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• v.23 no.3
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• pp.217-226
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• 2006

We report three sawtooth oscillation events observed at geosynchronous orbit where we find quasi-periodic (every 2-3 hours) sudden flux increases followed by slow flux decreases at the energy levels of ${\sim}50-400keV$. For these three sawtooth events, we have examined variations of the outer boundary of the outer radiation belt. In order to determine L values of the outer boundary, we have used data of relativistic electron flux observed by the SAMPEX satellite. We find that the outer boundary of the outer radiation belt oscillates periodically being consistent with sawtooth oscillation phases. Specifically, the outer boundary of the outer radiation belt expands (namely, the boundary L value increases) following the sawtooth particle flux enhancement of each tooth, and then contracts (namely, the boundary L value decreases) while the sawtooth flux decreases gradually until the next flux enhancement. On the other hand, it is repeatedly seen that the asymmetry of the magnetic field intensity between dayside and nightside decreases (increases) due to the dipolarization (the stretching) on the nightside as the sawtooth flux increases (decreases). This implies that the periodic magnetic field variations during the sawtooth oscillations are likely responsible for the expansion-contraction oscillations of the outer boundary of the outer radiation belt.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.435-438
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• 2002

The permeate flux was lower when PAC was added compared to without PAC system. It can be concluded that PAC is cause of membrane fouling. The effect of flow volume was found not significant for the three samples. But it was shown high rejection rate due to adsorption of organic matter to PAC in the case of adding PAC.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.478-482
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• 2015

This paper describes the torque calculation of Flux Switching Motor using Winding Function Theory. First of all, the optimized new Flux Switching Motor was proposed to minimize the torque ripple. The simulation results by the Winding Function Theory were compared with those from Finite Element Analysis. The revised Flux Switching Motor and experimental setup were manufactured. The simulation result by the Winding Function Theory was compared with that of the experiment. The comparison validated the analysis method of the Flux Switching Motor by Winding Function Theory.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.679-686
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• 2018

Reverse osmosis (RO) concentration of sodium chloride, sodium acetate, and sodium citrate solutions has been performed by polyamide RO membrane. Concentration polarization phenomena was also studied by changing pressure, solute kinds, and initial solution concentration. Pressure effect on permeation flux was that the increase of flux was accompanied by the increase of pressure. Flux increase was observed by the decrease of initial solution concentration. Surface concentration on the RO membrane increases and so flux declines due to the concentration polarization. In the later phase of concentration, concentration polarization effect was decreased by the back diffusion of solute from the polariztion layer. In case of sodium citrate, its large ion size and charge density resulted in the discrepancy between theory and experimental data of concentration polarization. It may be due to electric repulsion on the membrane surface.