• 멤브레인
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• 제11권2호
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• pp.74-82
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• 2001

실리콘(PDM)막을 통한 휘발성유기화합물(VOCs)과 질소 혼합물의 증기투과시 공급부 경계층에서 발생하는 VOCs의 농도분극 현상을 정량적인 평가를 위하여 저항직렬연결의 개념을 바탕으로 한 수학적인 모델식을 확립하였다. feed속도를 변화시키면서 여러 VOCs 혼합물에 대한 증기투과를 시행하였는데 본 연구에 사용한 VOCs는 염소화 탄화수소계 중에서 응축도가 다른 methylene chloride, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane 등을 선정하여 사용하였다. 확립한 모델식에 각 혼합물의 투과 실험치들의 frtting 및 regression을 통하여 각 모델 파라메타들을 구하고 물질전달계수 및 농도분극탄성률 등을 결정하였다. 결정한 모델 파라메타를 분석한 결과 VOCs의 응축도가 클수록 경계층 저항이 현저함을 관찰할 수 있었으며 또한 모델링을 통해서 고 투과성 고 선택성막을 통한 증기투과에서 경계층저항의 중요성을 확인할 수 있었다.

• 한국수소및신에너지학회논문집
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• 제19권3호
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• pp.209-216
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• 2008

In the present study, a mathematical model has been formulated for the performance of polymer electrolyte fuel cells. Modify the concentration polarization equation using concentration coefficient that represents the characteristics of bipolar plate reactant distribution. The model predictions have been compared with experimental results and good agreement has been demonstrated for the cell polarization curves. The effects of operating parameters on the performance of fuel cells have been studied. Increases of operation pressure reduce the effect of temperature on the performance.

• 한국가시화정보학회지
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• 제13권2호
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• pp.16-21
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• 2015

Concentration polarization(CP) phenomena show great potential on desalination technology. As we can control the dimension of silicon based nanochannel system, it can be used to model ion exchange membrane. In this study, to investigate the effect of nanochannel number and working conditions on the CP based desalination process, nanochannel based microfluidic system is fabricated. First, we optimized nanochannel number and working conditions to conduct visualization study on CP based desalination process. Second, we visualized the desalination process with fluorescent dye in the desalination chip. We also visualized that the particles also can be removed by the CP based desalination process.

• Korean Membrane Journal
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• 제4권1호
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• pp.7-11
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• 2002

A radial pleat module using a polysulfone membrane was developed. The permeation characteristics of the radial pleat module were compared with those of a flat plate module. The average module efficiency of the radial pleat module for the applied pressure range was 82% and was always greater than that of the spiral wound module. For the radial pleat module, in general, as the applied pressure increases, the flux increases and the rejection reduces. The concentration polarization causes the decrease of the flux for the long time operation. But it has been found that the radial pleat module is more efficient for the reduction of the concentration polarization because it has the more effective area per unit volume and can induce the turbulent flow in the module.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.333-346
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• 2018

This study presents a mathematical modeling approach for developing models based on non-ideal conditions related to the membrane structure including porous supporting layer and deformation under pressure. Comparison of the findings with experimental data reveal the importance of considering the resistance in porous supporting layer though the effect of concentration polarization in the permeate stream could be neglected. Investigations on deformation of fibers under pressure ascertain that at larger fiber inner radius to outer radius ratios, increasing driving force may lead to an initial increase in permeability. After that, the effects of deformation dominates and thus permeability may be decreased.

• 한국광학회:학술대회논문집
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• 한국광학회 2004년도 제15회 정기총회 및 동계학술발표회
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• pp.358-359
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• 2004

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.128-129
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• 2003

최근 수년간 polarimetry, Raman spectroscopy, near infrared (NIR) absorption spectroscopy, NIR scattering, optoacoustics 등의 방법을 통하여 비침습적으로 Glucose의 농도를 측정하려는 연구가 많이 시도되었다. 일반적으로 이들 방법은 sensitivity 와 signal-to-noise ratio가 매우 낮고 복잡한 알고리즘이 요구되어져 glucose 농도 측정에 한계가 있음이 드러났다. 본 연구에서는 polarization sensitive optical coherence tomography (PS-OCT)에 사용되는 polarization sensitive low coherence inter-ferometer (PS-LCI) 기법을 이용하여 비침습적으로 glucose의 농도 측정을 가능하게 하는 시스템 개발에 중점을 두었다. (중략)

• Corrosion Science and Technology
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• 제22권3호
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• pp.137-152
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• 2023

Polarization behavior and corrosion inhibition of copper in acidic chloride solutions containing benzotriazole were studied. Pourbaix diagrams constructed for copper in NaCl solutions with different BTAH concentrations were used to understand the polarization behavior. Open circuit potential (OCP) depended not only on chloride concentration, but also on whether a CuBTA layer was formed on the copper surface. Only when the (pH, OCP) was located well in the CuBTA region of the Pourbaix diagram, a stable corrosion inhibiting CuBTA layer was formed, which was confirmed by X-ray Photoelectron Spectroscopy (XPS) and a long-term corrosion test. The OCP for the CuBTA layer decreased logarithmically with increasing [Cl^-] activity in the solution. A minimum BTAH concentration required to form a CuBTA layer for a given NaCl concentration and pH were determined from the Pourbaix diagram. It was found that 320 ppm BTAH solution could be used to form a corrosion-inhibiting CuBTA layer inside the corrosion pit in the sprinkler copper tube, successfully reducing water leakage rate of copper tubes. These experimental results could be used to estimate water chemistry inside a corrosion pit.

• 공업화학
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• 제22권6호
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• pp.703-710
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• 2011

분리막 모듈 내 스페이서는 용액의 원활한 흐름을 위한 공간 확보와 더불어 유체의 난류를 형성시키므로 농도분극화 현상을 감소시키고 막 표면에 축적되는 오염물을 용액 내로 혼합하여 높은 투과유속과 분리막 모듈을 장기간 운전하는데 도움을 준다. 본 연구에서는 분리막 모듈 내 원형, 십자형, 다이아몬드형 및 육각형 단면의 스페이서와 스페이서의 배열 각도, 용질 배제율 및 투과유속에 대한 농도 변화를 "COMSOL Multiphysics" 프로그램으로 수치 해석하여 최적화하였다. 4가지 형태의 스페이서 중에서 십자형 단면 스페이서를 포함한 모듈의 경우가 분리막 표면 농도를 가장 낮게 유지하였으며 스페이서의 배열 각도는 $30^{\circ}$가 효율적이었다. 스페이서가 없는 모듈 출구에서 분리막 표면의 농도는 입구보다 약 2.09배까지 증가하였으나 가장 효율적인 십자형 스페이서를 $30^{\circ}$로 배열할 경우 약 1.29배로서 최대 37% 낮았다. 또한 투과유속이 증가할수록 십자형 스페이서의 농도분극 감소효과는 급격히 증가하였다.

• 한국농공학회논문집
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• 제55권2호
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• pp.21-27
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• 2013

The present study explored the way to desalinate seawater for agricultural irrigation using forward osmosis (FO) process using liquid fertilizer as draw solution. FO experiments were performed in a cross flow mode using flat sheet FO membrane. The effect of membrane orientation, flow rate, and draw solution concentration on the performance of forward osmosis was investigated by measuring water flux of forward osmosis membrane. The water flux when the draw solution was placed against the membrane active layer was lower than the water flux when the feed solution was placed against the membrane active layer. This results indicated that the decrease of effective osmotic pressure by dilutive internal concentration polarization was less than that by concentrative internal concentration polarization. Increasing flow rate from 66.7 to 133.1 $cm^3$/min resulted in increase of the water flux when the membrane active layer orient to draw solution and feed solution, respectively. The reduction of resistance to water flow increased water flux at higher flow rate. The water flux of FO membrane increased with increasing draw solution concentration from 10000 to 30000 mg/L. The water flux for $KH_2PO_4$ draw solution was similar to that for commercial fertilizer. Optimization of FO process would contribute to economically desalinate brackish water for agricultural use.