• Title/Summary/Keyword: phase-inversion method

Search Result 188, Processing Time 0.023 seconds

연속공정에 의한 UF용 폴리이미드 분리막의 제조

  • 김완주;전종영;탁태문
    • Proceedings of the Membrane Society of Korea Conference
    • /
    • 1995.04a
    • /
    • pp.45-45
    • /
    • 1995
  • Filtration, one of the most important process in the various industrials, is defined as the separation of two or more compounds from a fluid by passing the mixture refers to the separation of solid, immisible particles from liquid or gaseous mixture. Membrane filtration which is a type of filtration extends it's application further to include the separation, concentration, and filtration. The main objective of this investigation is the preparation of organic solvents-resistant polyimide membranes by using phase inversion technique and their application as a UF membrane. Specially, the dope solution was prepared from the newly developed method. The newly developed method is that the dope solution was directly prepared from the polyimide solution which was prepared by the modified one-step polymerization. The effects of the parameters for membrane preparation such as the casting solution composition and the casting conditions were investigated and the performance and chemical stabfiity of membrane are going to be tested.

  • PDF

Phase Behavior and Morphological Studies of Polysulfone Membranes; The Effect of Alcohols Used as a Non-solvent Coagulant (비용매 알코올 응고조를 이용한 폴리술폰 막의 상전이 거동 및 모폴로지 특성 연구)

  • Park Byung Gil;Kong Sung-Ho;Nam Sang Yong
    • Membrane Journal
    • /
    • v.15 no.4
    • /
    • pp.272-280
    • /
    • 2005
  • In this study, asymmetric polysulfone membranes were prepared by the phase inversion method and the casting solutions were containing N-methyl-2-pyrrolidone (NMP) as a solvent. Deionized water and various alcohols(methanol, ethanol, and propanol) were used as a coagulation medium in preparing asymmetric polysulfone membranes. This study investigates the effect of alcohol coagulants having different solubility parameters as a pore-former on the construction of porous structures and their pure water permeation properties. Asymmetric polysulfone membranes immersed in the pure alcohol coagulation bath solution showed the typical sponge-like structures and the reduced water permeability as compared with those of polysulfone membranes precipitated in the pure water coagulation bath solution. In the water/alcohol mixtures, asymmetric polysulfone membranes showed the finger-like structures with the sponge-like structures. Therefore, the sponge-like structure of polysulfone membrane was formed under the delayed demixing systems while the porosity of membrane was decreased significantly. The water permeability of polysulfone membrane precipitated in the pure water coagulant showed 164 [$L/m^2hr$] at 14.7 psi. In case of polysulfone membranes prepared in the pure methanol and ethanol coagulant, they showed the water permeability of 56 and 30 [$L/m^2hr$], respectively.

Research of Phase Correlation Method for Identifying Quantitative Similarity in Adjacent Real-time Streaming Frame

  • Cho, Yongjin;Yun, Yeji;Lee, Kyou-seung;Oh, Jong-woo;Lee, DongHoon
    • Proceedings of the Korean Society for Agricultural Machinery Conference
    • /
    • 2017.04a
    • /
    • pp.157-157
    • /
    • 2017
  • To minimize the damage by wild birds and acquire the benefits such as protection against weeds and maintenance of water content in soil, the mulching black color vinyl after seeding should be carried out. Non-contact and non-destructive methods that can continuously determine the locations are necessary. In this study, a crop position detection method was studied that uses infrared thermal image sensor to determine the cotyledon position under vinyl mulch. The moving system for acquiring image arrays has been developed for continuously detecting crop locations under plastic mulching on the field. A sliding mechanical device was developed to move the sensor, which were arranged in the form of a linear array, perpendicular to the array using a micro-controller integrated with a stepping motor. The experiments were conducted while moving 4.00 cm/s speed of the IR sensor by the rotational speed of the stepping motor based on a digital pulse width modulation signal from the micro-controller. The acquired images were calibrated with the spatial image correlation. The collected data were processed using moving averaging on interpolation to determine the frame where the variance was the smallest in resolution units of 1.02 cm. Non-linear integral interpolation was one of method for analyzing the frequency using the normalization image and then arbitrarily increasing the limited data value of $16{\times}4pixels$ in one frame. It was a method to relatively reduce the size of overlapping pixels by arbitrarily increasing the limited data value. The splitted frames into 0.1 units instead of 1 pixel can propose more than 10 times more accurate and original method than the existing correction method. The non-integral calibration method was conducted by applying the subdivision method to the pixels to find the optimal correction resolution based on the first reversed frequency. In order to find a correct resolution, the expected location of the first crop was indicated on near pixel 4 in the inversion frequency. For the most optimized resolution, the pixel was divided by 0.4 pixel instead of one pixel to find out where the lowest frequency exists.

  • PDF

Effects of Solvent on the Fabrication of Poly(L-lactide) Scaffold Membranes through Phase Inversion (상전이를 통한 Poly(L-lactide) 스캐폴드 막의 제조에서의 용매의 효과)

  • Cho, Yu Song;Kim, Young Kyoung;Koo, Ja-Kyung;Park, Jong Soon
    • Membrane Journal
    • /
    • v.24 no.2
    • /
    • pp.113-122
    • /
    • 2014
  • Porous poly(L-lactic acid)(PLLA) scaffold membranes were prepared via. phase separation process. Chloroform, dichloromethane and 1,4-dioxane were used as solvent and, ethyl alcohol was used as non-solvent. Morphologies, mechanical properties and mass transfer characteristics of the scaffold membranes were investigated through SEM, stress-strain test and glucose diffusion test. The scaffold membranes obtained from the casting solutions with chloroform and with dichloromethane showed similar morphologies. They showed sponge-like porous structure with the pore size in the range of $3-10{\mu}m$ and, their porosities were in 50-80% range. Using 1,4-dioxane as solvent, nano-fibrous scaffold membranes with porosities over 80% were fabricated. When the polymer content in the solution with 1,4-dioxane was lowered to 4%, highly porous, macroporous and nano-fibrous scaffold membranes were obtained. The size of the macropore was tens of the microns and the porosity was around 90%. These results indicate that the solvent has significant effect on the scaffold membrane structure and, that scaffold membranes with various structures can be fabricated through phase separation method by choosing solvent and by controlling polymer concentration in the casting solution.

CMP cross-correlation analysis of multi-channel surface-wave data

  • Hayashi Koichi;Suzuki Haruhiko
    • Geophysics and Geophysical Exploration
    • /
    • v.7 no.1
    • /
    • pp.7-13
    • /
    • 2004
  • In this paper, we demonstrate that Common Mid-Point (CMP) cross-correlation gathers of multi-channel and multi-shot surface waves give accurate phase-velocity curves, and enable us to reconstruct two-dimensional (2D) velocity structures with high resolution. Data acquisition for CMP cross-correlation analysis is similar to acquisition for a 2D seismic reflection survey. Data processing seems similar to Common Depth-Point (CDP) analysis of 2D seismic reflection survey data, but differs in that the cross-correlation of the original waveform is calculated before making CMP gathers. Data processing in CMP cross-correlation analysis consists of the following four steps: First, cross-correlations are calculated for every pair of traces in each shot gather. Second, correlation traces having a common mid-point are gathered, and those traces that have equal spacing are stacked in the time domain. The resultant cross-correlation gathers resemble shot gathers and are referred to as CMP cross-correlation gathers. Third, a multi-channel analysis is applied to the CMP cross-correlation gathers for calculating phase velocities of surface waves. Finally, a 2D S-wave velocity profile is reconstructed through non-linear least squares inversion. Analyses of waveform data from numerical modelling and field observations indicate that the new method could greatly improve the accuracy and resolution of subsurface S-velocity structure, compared with conventional surface-wave methods.

Membrane contactor and Carbon Dioxide Separation

  • 이규호
    • Proceedings of the Membrane Society of Korea Conference
    • /
    • 2002.07a
    • /
    • pp.59-101
    • /
    • 2002
  • PVDF is good material for a hollow fiber membrane with high porosity and excellent hydrophobicity. Asymmetric PVDF hollow fiber membranes were prepared by the Loeb-Sourirajan phase inversion method. Asymmetric PVDF hollow fiber membranes could be controlled in pore size and porosity using various additives(LiCl, ZnCl$_2$) and internal coagulants (water, EtOH/water, and DMAc/water mixture). $CO_2$removal efficiency of asymmetric PVDF hollow fiber membranes was 1.2 times high than that of commercialized PP hollow fiber membranes at MEA 5wt% solution. $CO_2$flux of asymmetric PVDF hollow fiber membranes was 2.5 times higher than that of commercialized PP hollow fiber membranes. $CO_2$removal efficiency and absorption rate of asymmetric PVDF hollow fiber membranes were 30 times higher than those of packed column at absorbent $H_2O$. $CO_2$flux of asymmetric PVDF hollow fiber membranes at MEA 5wt% solution was 48 times higher than that of pure water. In the case of MEA 5wt% solution used as an absorbent, the $CO_2$absorption rate and removal efficiency of PVDF hollow fiber membrane were 2.3 times higher than that of a packed column.

  • PDF

The Mathematical Model on Crosstalk Effect of Airborne Noise Sources and Verification based on Comparison between Transfer Path Analysis Methods (소음원간 누화 효과에 대한 수학적 모델 및 전달 경로 분석법 비교를 통한 검증)

  • Byun, Jae-Hwan;Kim, Yoon-Jae;Kang, Yeon-June;Kang, Koo-Tae;Kwon, O-Jun;Hong, Jin-Chul
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.18 no.9
    • /
    • pp.943-951
    • /
    • 2008
  • In this paper, the mathematical model on crosstalk effect between acoustic noise sources is presented. Based on this model, a theoretical value to quantitate crosstalk effect of sources can be defined on the authority of reverberation property of surrounding which sources are located, relative magnitudes of sources and phase deference between acoustic wave transferred from all of sources. In order to verify crosstalk effect factor, experiments are made for two cases, weak and strong crosstalk effect condition, by using toro representative transfer path analysis(TPA) methods.

A new approach to control of variable reluctance motors for DD robots (DD 로봇용 VR 모터의 제어를 위한 새로운 방식)

  • 김창환;하인중;하태균;고명삼;김동일
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1992.10a
    • /
    • pp.664-669
    • /
    • 1992
  • In this paper, we present a DSP-based high dynamic performance torque control scheme of variable reluctance motors(VRM's) for DD(Direct Drive) robots via function inversion technique. The VRM with our controller behaves like DC motors, and hence developed torque tracks given torque command accurately with no torque ripples. Furthermore, our torque control algorithm ensures the production of maximum constant torque under maximum current limitation, minimizes power loss in each phase resistance, and takes magnetic saturation effect into account. Also, since our control algorithm is represented in the form of look-up table, it can be easily implemented with simple digital circuits and this tabular design method is computationally more accurate and simpler compared to the prior methods.

  • PDF

Adsorption mechanism of copper ions on porous chitosan membranes: Equilibrium and XPS study

  • Ghaee, Azadeh;Zerafat, Mohammad Mahdi
    • Membrane and Water Treatment
    • /
    • v.7 no.6
    • /
    • pp.555-571
    • /
    • 2016
  • Heavy metal contamination has attracted considerable attention during recent decades due to the potential risk brought about for human beings and the environment. Several adsorbent materials are utilized for the purification of contaminated water resources among which chitosan is considered as an appropriate alternative. Copper is a heavy metal contaminants found in several industrial wastewaters and its adsorption on porous and macroporous chitosan membranes is investigated in this study. Membranes are prepared by phase inversion and particulate leaching method and their morphology is characterized using SEM analysis. Batch adsorption experiments are performed and it is found that copper adsorption on macroporous chitosan membrane is higher than porous membrane. The iso-steric heat of adsorption was determined by analyzing the variations of temperature to investigate its effect on adsorption characteristics of macroporous chitosan membranes. Furthermore, desorption experiments were studied using NaCl and EDTA as eluants. The mechanism of copper adsorption was also investigated using XPS spectroscopy which confirms simultaneous occurrence of chelation and electrostatic adsorption mechanisms.

Synthesis and Characterization of Copoly(amide-imide) Derivatives and Ultrafiltration Membrane Performances II - Permeation Properties of Copoly(amide-imide)s Ultrafiltration Membranes -

  • Jeon, Jong- young;Kim, Jong-hp
    • Korean Membrane Journal
    • /
    • v.3 no.1
    • /
    • pp.24-31
    • /
    • 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.

  • PDF