• Journal of Life Science
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• v.10 no.2
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• pp.131-139
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• 2000

Lecithin-free egg yolk protein (EYP), the by-product of lecithin extraction from egg yolk, which is denatured with an organic solvent, would normally be discarded. In this study, the denatured protein was renatured with alkali, and hydrolyzed with Alcalase in order to utilize by-product. The hydrolysate was separated through a series of ultrafiltration membranes with molecular weight cut-off (MWOO) of 10, 5 and 1 kDa, and the antioxidative activities of the hydrolysates was investigated. The 5K hydrolysate, permeate from 5 kDa membrane, showed stronger antioxidative activity than 10 K and 1 K hydrolysate which were permeated from 10 kDa and 1 kDa membrane, in a linoleic acid autoxidation system. In addition, the optimum concentration of antioxidative activity for 5 K hydrolysate was 1%, and the activity was about 37% higher as compared with α-tocopherol. The synergistic effect was also increased by using the hydrolysates with α-tocopherol.

• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.67-72
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• 1997

To evaluate the effectiveness of water treatment using nanofiltration, ultrafiltration, and microfiltration systems, tapwater contaminated by bacteria and nitrate nitrogen was filtered, and then the rates of removal for many kinds of contaminants were comp.ared and investigated. The rates of turbidity removal by these systems are around 80% all of them. However, nanofiltration system is the most effective as hardness removal is 80%, suspended solids 90%, total residual chlorine 90% and nitrate nitrogen 69%. Among nanofiltration, ultrafiltration and microfiltration systems, nanofiltration system is the most stable in flow rate of permeate. Comparing hollow and spiral type of ultrafiltration, microfiltration each, spiral type is more stable than hollow type owing to rinsing effect of brine. The values of pH in ultrafiltration and microfiltration systems are between 7, 0 and 7.5, and that of nanofiltration system is low to 6.2-7.0. The effectiveness of heterotrophic bacteria removal is the most excellent in the nanofiltration system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.67-70
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• 1994

On this study, we fabricated humudity sensor with polyimide thin film from the nonaqueous emulsion by the electrophoretic deposition as a function of film thickness. then evaluated performance of the sensor with increasing relative humidity if constant temperature constant humidity chamber, which is electronically controlled. we designed upper electrode of the sensor to brush type to make moisture particles permeate into the polymer bulk. sensing properties of the sensor on % RH shows proportion on the low %RH. Fer the 30V-30S- 200$^{\circ}C$ sample, percentage changing of capacitance on from 30 %RH to 90 %RH is 45.8 %, and increasing rate per 1 % RH of capacitance is 11.25 pF

• Korean Membrane Journal
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• v.3 no.1
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• pp.24-31
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• 2001

Ultrafiltration membranes base on copoly(amide-imide) derivatives were prepared by the phase inversion method and the factors determining the permeation characteristics of membrane were investigated. The permeation behavior was observed by the relative ratio of permeate flux (J$\_$t/)/pure water flux (J$\_$o/). The characteristics through membrane were measured using aqueous solution of poly(ethyleneglycol) (MW 2.0$\times$10$\^$4/) over a temperature range of 10∼90$\^{C}$. With increasing the operating temperature, the relative ratio of flux became high. All the membranes had good chemical stability. Copoly(amide-imide) membranes having various Permeation properties could be obtained. Further, it was proved that the membrane performances could be determined from the preparation conditions as well as various operating conditions.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.03a
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• pp.127-158
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• 1996

투과증발은 막분리 기술의 하나로 역삼투막, 한외여과막 등의 다른 막분리와 달리 혼합물 분리가 막소재 물질과 분리 대상 유기물 사이의 화학 친화도에 의해 이루어지기 때문에 혼합물중의 특정 성분에 대한 선택도가 높은 비다공성 고분자 복합막이 사용된다. 투과증발막 투과의 구동력은 투과 성분의 활동도(activity) 차로 이는 부분 증기압차로 구체화되며, 이 구동력을 높이기 위해서 feed side는 고온 유지를 위한 열교환기가 필요하며 permeate side는 진공하에서 감압에 의한 증기상으로의 전환을 이루게 하며 이를 다시 응축하여 연속 투과가 일어날 수 있게 한다. 따라서 투과증발의 핵심 기술은 분리하고자 하는 물질에 대하여 높은 투과선택도(permselectivity)를 갖는 투과증발막의 제조 기술이며, 제조된 막을 실공정에 적용하기 위한 모듈 설계, 제작 기술과 이를 시스템화하여 실규모로 Scale-up 할 수 있는 시스템 설계 기술도 실용화를 위해서 반드시 이루어져야 한다.

• Membrane Journal
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• v.7 no.2
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• pp.57-64
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• 1997

Membrane Distillation(MD) is reviewed as an application to new separation technology. Hydrophobic membrane which has been used to microfiltration is feasible material for MD process. MD has perfect selectivity under moderate temperature and is promised to simplify typical water treatment process. The principle of MD separation is phase transition by vapor-liquid interface at the pore of membrane surface. Feed and permeate temperature, composition, membrane wetting, heat and mass transfer phenomena affect the selectivity and flux of MD.

• Water Engineering Research
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• v.4 no.1
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• pp.1-17
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• 2003

A mathematical model was developed to simulate the performance of a prototype wind-powered reverse osmosis desalination system. The model consists of two sub-models operated in a series. The first sub-model is the wind-energy conversion sub-model, which has wind energy and feed water as its input and pressurized feed water as its output. The second sub-model is a reverse osmosis (RO) process sub-model, with pressurized feed water as its input and the flow and salinity of the product water or permeate as its output. Model coefficients were determined based on field experiments of a prototype wind powered RO desalination system of the University of Hawaii, from June to December 2001. The mathematical model developed by this study predicts the performance of wind-powered RO desalination systems under different design conditions. The system optimization is achieved using a linear programming approach. Based on the results of system optimization, a design guide is prepared, which can be used by both manufacturer and end-user of the wind-driven reverse osmosis system.

• Membrane and Water Treatment
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• v.10 no.5
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• pp.387-394
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• 2019

Membrane distillation (MD) is one of the water treatment processes which involves the momentum, heat and mass transfer through channels and membrane. In this study, CFD modeling has been used to simulate the heat and mass transfer in the direct contact membrane distillation (DCMD). Also, the effect of operating parameters on the water flux is investigated. The result shows a good agreement with the experimental result. Results indicated that, while feed temperature is increasing in the feed side, water flux improves in the permeate side. Since higher velocity leads to the higher mixing and turbulence in the feed channel, water flux rises due to this increase in the feed velocity. Moreover, results revealed that temperature polarization coefficient is rising as flow rate (velocity) increases and it is decreasing while the feed temperature increases. Lastly, the thermal efficiency of direct contact membrane distillation is defined, and results confirm that thermal efficiency improves while feed temperature increases. Also, flow rate increment results in enhancement of thermal efficiency.

• Journal of Industrial and Engineering Chemistry
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• v.67
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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.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.51-61
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• 2022

Gas separation via hollow fibre membrane modules (HFMM) is deemed to be a promising technology for natural gas sweetening, particularly for lowering the level of carbon dioxide (CO₂) in natural gas, which can cause various problems during transportation and process operation. Separation performance via HFMM is affected by membrane properties, module specifications and operating conditions. In this study, a mathematical model for HFMM is developed, which can be used to assess the effects of the aforementioned variables on separation performance. Appropriate boundary conditions are imposed to resolve steady-state values of permeate variables and incorporated in the model equations via an iterative numerical procedure. The developed model is proven to be reliable via model validation against experimental data in the literature. Also, the model is capable of capturing axial variations of process variables as well as predicting key performance indicators. It can be extended to simulate a large-scale plant and identify an optimal process design and operating conditions for improved separation efficiency and reduced cost.