• 제목/요약/키워드: Through Pore

검색결과 914건 처리시간 0.024초

Water transport through hydrophobic micro/nanoporous filtration membranes on different scales

  • Mian, Wang;Yongbin, Zhang
    • Membrane and Water Treatment
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    • 제13권6호
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    • pp.313-320
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    • 2022
  • Theoretical calculation results are presented for the enhancement of the water mass flow rate through the hydrophobic micro/nano pores in the membrane respectively on the micrometer and nanometer scales. The water-pore wall interfacial slippage is considered. When the pore diameter is critically low (less than 1.82nm), the water flow in the nanopore is non-continuum and described by the nanoscale flow equation; Otherwise, the water flow is essentially multiscale consisting of both the adsorbed boundary layer flow and the intermediate continuum water flow, and it is described by the multiscale flow equation. For no wall slippage, the calculated water flow rate through the pore is very close to the classical hydrodynamic theory calculation if the pore diameter (d) is larger than 1.0nm, however it is considerably smaller than the conventional calculation if d is less than 1.0nm because of the non-continuum effect of the water film. When the driving power loss on the pore is larger than the critical value, the wall slippage occurs, and it results in the different scales of the enhancement of the water flow rate through the pore which are strongly dependent on both the pore diameter and the driving power loss on the pore. Both the pressure drop and the critical power loss on the pore for starting the wall slippage are also strongly dependent on the pore diameter.

Comparison of the Mercury Intrusion Porosimerty, Capillary Flow Porometry and Gas Permeability of Eleven Species of Korean Wood

  • Jang, Eun-Suk;Kang, Chun-Won;Jang, Sang-Sik
    • Journal of the Korean Wood Science and Technology
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    • 제46권6호
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    • pp.681-691
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    • 2018
  • The typical methods of mercury intrusion porosimetry (MIP) and capillary flow porometry (CFP) were used to evaluate the pore size of cross-section of wood and the effect of the pore structure on the permeability of wood was analyzed in this study. The results of this study were as followings: The pore size of wood measured by CFP was larger than that measured by MIP except for Lime tree, Korean red pine and Paulownia. Among the three pore types of porous materials defined by IUPAC (through pores, blind pores, and closed pores), only through pores are related to permit fluid flow. MIP measures the pore size of both through pores and blind pores, while CFP measures the pore size of only constricted through pores. Therefore, pore size measured by MIP was not related to gas permeability, however pore size measured by CFP had a proportional relationship with gas permeability.

Pore Characterization in Cross Section of Yellow Poplar (Liriodendron tulipifera) Wood

  • Jang, Eun-Suk;Kang, Chun-Won;Jang, Sang-Sik
    • Journal of the Korean Wood Science and Technology
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    • 제47권1호
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    • pp.8-20
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    • 2019
  • This study was conducted to analyze the pore structure of Yellow poplar. Cross-sectional surfaces of heartwood and sapwood of Yellow poplar (Liriodendron tulipifera) were observed by SEM, and the true density of the heartwood, intermediate wood and sapwood were measured by gas pycnometery, while gas permeability and pore size of heartwood, intermediate wood and sapwood were measured by capillary flow porometery. The pores were classified as through pore, blind pore and closed pore. It was determined that the permeability was increased due to the content and size of through pore being increased although the total porosity of specimen showed slight difference from pith to bark. The content of through pore porosity was 33.754 % of heartwood and 47.810 % of sapwood, showed an increasing trend from pith to bark, however, those for the blind pore porosity and closed pore porosity were 27.890 % and 19.492 % for heartwood and 19.447 % and 4.660 % for sapwood, showed a decreasing trend from pith to bark. The max pore size of specimens was increased by about 5 times from $5.927{\mu}m$ to $31.334{\mu}m$, and mean flow pore size was increased by about 315 times from $0.397{\mu}m$ to $12.437{\mu}m$ from pith to bark.

용질배제 곡선에 의한 한외여과 막의 세공특성 예측 (Prediction of Intrinsic Pore Properties of Ultrafiltration Membrane by Solute Rejection Curves)

  • 염경호
    • 한국막학회:학술대회논문집
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    • 한국막학회 1991년도 추계 총회 및 학술발표회
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    • pp.4-8
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    • 1991
  • The characterization of pore properties (mean pore size and pore size distribution) of the active layer in a UF membrane is important not only in order to obtain information about the factors affecting pore formation during membrane manufacturing but also to understand deeply the mechanism of solute and solvent transport through pores. Many methods of characterizing quantitatively the pore properties of UF membranes have been suggested in the literature: solvent and gas flow measurement, bubble point determination, electron microscopy, gas adsorption/desorption measurement, rejection measurement etc. But most of these methods involve time-consuming procedures and involve some wellknown problems and uncertainties.

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다중 선형 회귀 기반 기계 학습을 이용한 인공지지체의 사각 기공 형태 진단 모델에 관한 연구 (A Study on Square Pore Shape Discrimination Model of Scaffold Using Machine Learning Based Multiple Linear Regression)

  • 이송연;허용정
    • 반도체디스플레이기술학회지
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    • 제19권4호
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    • pp.59-64
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    • 2020
  • In this paper, we found the solution using data based machine learning regression method to check the pore shape, to solve the problem of the experiment quantity occurring when producing scaffold with the 3d printer. Through experiments, we learned secured each print condition and pore shape. We have produced the scaffold from scaffold pore shape defect prediction model using multiple linear regression method. We predicted scaffold pore shapes of unsecured print condition using the manufactured scaffold pore shape defect prediction model. We randomly selected 20 print conditions from various predicted print conditions. We print scaffold five times under same print condition. We measured the pore shape of scaffold. We compared printed average pore shape with predicted pore shape. We have confirmed the prediction model precision is 99 %.

나노 세공을 통한 비드 체인의 전기영동에 관한 수치해석적 연구 (NUMERICAL STUDY ON ELECTROPHORETIC MOTION OF A BIO-POLYMER THROUGH A NANO-PORE)

  • 알라파티 수레수;서용권
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2010년 춘계학술대회논문집
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    • pp.575-580
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    • 2010
  • In this work, the electrophoretic motion of dsDNA molecule represented by a polymer through an artificial nano-pore in a membrane is simulated using the numerical method combining the lattice Boltzmann and Langevin molecular dynamic method. The polymer motion is represented by Langevin molecular dynamics technique while the fluid flow is taken into account by fluctuating lattice-Boltzmann method. The hydrodynamic interactions between the polymer and solvent in a confined space with a membrane having a hole are considered explicitly through the frictional and the random forces. The electric field intensity over the space is obtained from a finite difference method. Initially, the polymer is placed at one side of the space, and an electric field is applied to drive the polymer to the other side of the space through the nano-pore. In future, we plan to study the effect of the polymer size and the electric field on the electrophoretic velocity.

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콘크리트 중의 공극 특성에 따른 전위차 염소이온 확산계수 (Effect of Pore-Characteristics of Concrete on the Diffusion Coefficient of Chloride Using the Accelerating Test Methods)

  • 문한영;김홍삼;최두선;오세민
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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    • pp.711-714
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    • 2003
  • Factors causing deterioration of concrete structures under marine environment are various, especially penetration and diffusion of chloride ion, carbon dioxide, and water through pore effects on the durability of concrete as well as mechanical properties of concrete. Pore of porous materials like concrete can be classified as micro-, meso-, and macro-pore. And pore of cement matrix is classified as pore which occupied by water, air void, and ITZ between cement paste and aggregates. In this study, to verify the relationship between pore of cement matrix and the property of chloride ion diffusivity, the regression analysis is producted. From the result of regression analysis, the average pore diameter more than total pore volume effects on the diffusivity of chloride ion.

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The formation of highly ordered nano pores in Anodic Aluminum Oxide

  • Im, Wan-soon;Cho, Kyung-Chul;Cho, You-suk;Park, Gyu-Seok;Kim, Dojin
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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    • pp.53-53
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    • 2003
  • There has been increasing interest in the fabrication of nano-sized structures because of their various advantages and applications. Anodic Aluminum Oxide (AAO) is one of the most successful methods to obtain highly ordered nano pores and channels. Also It can be obtained diverse pore diameter, density and depth through the control of anodization condition. The three types of substrates were used for anodization; sheets of Aluminum on Si wafer and Aluminum on Mo-coated Si wafer. In Aluminum sheet, a highly ordered array of nanoholes was formed by the two step anodization in 0.3M oxalic acid solutions at 10$^{\circ}C$ After the anodization, the remained aluminum was removed in a saturated HgCl$_2$ solution. Subsequently, the barrier layer at the pore bottom was opened by chemical etching in phosphoric acid. Finally, we can obtain the through-channel membrane. In these processes, the effect of various parameters such as anodizing voltage, anodizing time, pore widening time and pre-heat treatment are characterized by FE-SEM (HITACH-4700). The pore size. density and growth rate of membrane are depended on the anodizing voltage and temperature respectively. The pore size is proportional to applied voltage and pore widening time The pore density can be controlled by anodizing temperature and voltage.

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Borehole stability analysis in oil and gas drilling in undrained condition

  • Wei, Jian-Guang;Yan, Chuan-Liang
    • Geomechanics and Engineering
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    • 제7권5호
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    • pp.553-567
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    • 2014
  • Borehole instability during drilling process occurs frequently when drilling through shale formation. When a borehole is drilled in shale formation, the low permeability leads to an undrained loading condition. The pore pressure in the compressed area near the borehole may be higher than the initial pore pressure. However, the excess pore pressure caused by stress concentration was not considered in traditional borehole stability models. In this study, the calculation model of excess pore pressure induced by drilling was obtained with the introduction of Henkel's excess pore pressure theory. Combined with Mohr-Coulumb strength criterion, the calculation model of collapse pressure of shale in undrained condition is obtained. Furthermore, the variation of excess pore pressure and effective stress on the borehole wall is analyzed, and the influence of Skempton's pore pressure parameter on collapse pressure is also analyzed. The excess pore pressure decreases with the increasing of drilling fluid density; the excess pore pressure and collapse pressure both increase with the increasing of Skempton's pore pressure parameter. The study results provide a reference for determining drilling fluid density when drilling in shale formation.

다공성 세라믹스와 다공질층을 포함하는 적층체의 제조에 관한 연구;I. 기공구조 (Fabrication of Porous Ceramics and Multi-layered Ceramics Containing Porous Layers; I. Pore Structure)

  • 이해원;윤복규;송휴섭
    • 한국세라믹학회지
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    • 제31권9호
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    • pp.1044-1052
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    • 1994
  • Tape casting technique was successfully applied to produce porous ceramics and multi-layered ceramics containing porous layers, where spherical hollow polymer particles were introduced as pore precursors. In the presence of extreme differences in density and size between Al2O3 and pore precursor particles, hindered settling was effective in preventing segregation of component particles and packing behavior of mixed powders was improved through bimodal packing. There were two transitions in packing behavior of mixed powders. The first transition took place at 40~50 vol% pore precursor addition, where majority of pores changed from close to open pore state. The other transition occured at 60~70 vol% pore precursor addition, where pore precursor particles formed a continuous network structure.

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