• Title/Summary/Keyword: Internal membrane

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A Study on Air Flow Analysis for the Internal Space of the Dehumidifying Air-Conditioning System with A Membrane (분리막 제습공조시스템의 내부 유동 해석에 관한 연구)

  • Jung, Yong-Ho;Park, Seong-Ryong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.12
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    • pp.620-625
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    • 2015
  • The summer climate is very hot and humid in Korea. Humidity is an important factor in determining thermal comfort. Recently, research on dehumidification device development has been attempted to save the energy required for operating the dehumidifier. Existing dehumidification systems have disadvantages such as wasting energy to drive the compressor. Meanwhile, dehumidification systems with membranes can dehumidify humid air without increasing the dry bulb temperature. Therefore. they don't have to consume cooling energy. In this paper, the installation conditions for a membrane system were analyzed to improve the shape and optimum performance of the system. The results showed that the distance between elements was the critical system design factor, and that a distance of 20 mm was the optimal condition for the pressure drop and flow characteristics of the internal air flow.

Cell Recycled Culture of Succinic Acid-Producing Anaerobiospirillum succiniciproducens Using an Internal Membrane Filtration System

  • Lee, Pyung-Cheon;Lee, Sang-Yup;Chang, Ho-Nam
    • Journal of Microbiology and Biotechnology
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    • v.18 no.7
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    • pp.1252-1256
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    • 2008
  • Cell recycled culture of succinic acid-producing Anaerobiospirillum succiniciproducens was anaerobically carried out using an internal membrane filter module in order to examine the physiological response of A. succiniciproducens to a high-cell-density environment. The optimal growth of A. succiniciproducens and its enhanced succinic acid productivity were observed under $CO_2$-rich conditions, established by adding $NaHCO_3$ and $Na_2CO_3$, in the cell recycled system. A. succiniciproducens grew up to 6.50 g-DCW/l, the highest cell concentration obtained so far, in cell recycled cultures. The cells did not change their morphology, which is known to be easily changed in unfavorable or stress environments. The maximum productivity of succinic acid was about 3.3 g/l/h, which is 3.3 times higher than those obtained in batch cultures. These results can serve as a guide for designing highly efficient cell recycled systems for succinic acid at a commercial level.

Fabrication and Properties Analysis of MEA for PEMFC (고분자전해질 연료전지용 MEA 제조 및 특성평가)

  • Cho Y.H.;Cho Y.H.;Park I.S.;Sung Y.E.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.230-234
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    • 2005
  • Fabrication of MEA is important factor for proton exchange membrane fuel cell (PEMFC). MEA of PEMFC with hot pressing and direct coating method were prepared, and performances were evaluated and compared each other. The effect of MEA preparation methods, hot pressing methods and direct coating methods, on the cell performance was analyzed by impedance spectroscopy and SEM. The performance of PEMFC with direct coating method was better than with hot pressing method because membrane internal resistance and membrane-interfacial resistance were reduced by elimination of hot pressing process in MEA fabrication. In addition the micro structure of MEA with direct coating method reveals uniform interface between membrane and catalyst layer.

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Mechanisms of Gas Permeation through Microporous Membranes - A Review (미세 다공막을 통한 기체 투과기구)

  • 황선탁
    • Membrane Journal
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    • v.7 no.1
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    • pp.1-10
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    • 1997
  • A review is presented for various gas transport mechanisms through microporous membranes of both polymeric and inorganic materials. Different transport modes manifest depending on the pore size and the flow regime, which is a function of pressure, temperature, and the interaction between gas molecules and the pore walls. For microporous membranes whose pores are small and the internal surface area huge, the surface diffusion becomes a significant factor. If the pores become even smaller, then the transport mechanism will be more of an activated diffusion type. When conditions are right capillary condensation will take place to create an enormous capillary pressure gradient, which will greatly enhance the permeation flux. At the same time the capillary condensate of the heavier component may block the membrane pores denying the passage of the lighter gas molecules. All of these phenomena will influence the separation of mixtures.

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Preparation of Wool/Poly(ethylene terephthalate) Composite Membrane and It's Dyeablities (모/폴리에틸렌테레프탈레이트 복합막의 제조와 염색성)

  • Kim, Gong-Ju;Shin, Hye Kyong;Park Mi-Ra;Kim, Kyong-Hi;Jeon, Jae-Hong
    • Textile Coloration and Finishing
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    • v.9 no.1
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    • pp.23-32
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    • 1997
  • Composite membranes having different mixing ratio of Wool(SCMK) and poly(ethylene terephthalate) (PET) were prepared by dissolving wool/PET in hexafluoro-2-propanol(HFIP), casting the obtained solution on a glass plate and evaporation the solvent in the presence and absence of an electric field. The internal structure of the prepared membrane was investigated using polarise microscope dyeing and dye permeation method. In the composite membrane prepared under electric field, both components were micro mixing, while in the membranes prepared under nonelectric field, the two components formed a random sea/island structure according to different mixing ratio. Such characteristic membrane structure was influenced the permeation behavior of C.I. Acid Red 118 through the membranes from an aqueous solution.

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Effect of Foulant Characteristics on Membrane Fouling Index (오염물질의 특성이 막오염 지수에 미치는 영향)

  • Park, Chanhyuk;Kim, Hana;Hong, Seungkwan
    • Journal of Korean Society of Water and Wastewater
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    • v.19 no.6
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    • pp.775-780
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    • 2005
  • This study was performed to investigate the effect of foulant characteristics on Membrane fouling index such as Silt Density Index (SDI) and Modified Fouling Index (MFI). A linear relationship was found relating the fouling index (both SDI and MFI) on particle concentration, but fouling index values were nonlinearly (exponentially) with increasing organic concentration. When organic matter was the primary cause of fouling, the MFI was not accurately predicted due to internal fouling such as pore adsorption. The fouling index was determined mainly by particle characteristics when both particle and organic coexisted in the feed water. This observation was attributed to lessening of organic pore adsorption by particle cake layer formed on the membrane surface. Bench-scale actual fouling experiments demonstrated that permeate flux declines much faster with feed water containing particles than organic matters although fouling potential predicted by SDI values were identical, indicating that the accurate prediction of fouling potential requires the development of fouling index reflecting different foulant characteristics.

Separation of Chromium(VI) Ion in Industrial Waste Water throunh Liquid Surfactant Membrane (산업폐수중 유화액막에 의한 크롬(VI)의 분리)

  • 초민승;강안수;우인성;이영순
    • Journal of the Korean Society of Safety
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    • v.4 no.1
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    • pp.15-24
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    • 1989
  • The transport of Chromium(Vl) ion from waste water throughl the liquid surfactant membrane containing tri-n-octylamine as a carrier, was analyzed by a slab model and was investigated through experiments. For the experiment of membrane stability, concentrations of surfactant and liquid parafnn oil were analyzed. Extraction euperiments were carried out to observe the effect of system variables, such as stirring speed, concentration of carrier, and NaOH in internal aqueous phase, and concentrations of H$_2$SO$_4$and initial chromium(VI) ion in external aqueous phase at $25^{\circ}C$. It is concluded that the most stable formation of liquid membrane emulsion was obtained when surfactant concentration is above 3 wt. % and liquid parafnn oil concentration is 50 vol. %. The transport of chromium(VI) ion in bacth extractor increased with increasing carrier concentration, the volume ratio of emulsion to external aqueous phases, and initial concentration of chromium(VI) ion under the optimum stirring speed of chromium(VI) ion below 2 ppm. The theoretical equation on the transport of chromium(Vl) ion agreed well with the experimental results.

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Preparation and Properties of NBR-Clay Hybrid Membranes (NBR-Clay 하이브리드 막의 제조 및 물성)

  • 남상용;김영진
    • Membrane Journal
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    • v.14 no.2
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    • pp.132-141
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    • 2004
  • NBR-Clay hybrid membranes were prepared by melt intercalation method with internal mixer and two roll mills. MMT was intercalated or ekfoliated by the NBR and it was confirmed by X-ray diffraction method. D-spacing of the characteristic peak from MMT plate in WAXD was moved and diminished. Gas permeability, mechanical properties and thermal properties of the NBR-Clay hybrid membranes were investigated. Gas permeability through the NBR-Clay hybrid membranes decreased due to increased tortuosity made by intercalation of clay in NBR.

The Effects of Duchesnea india(Audra.) Foche. on Human Stomach Cancer Cells (사매가 위암세포에 미치는 영향)

  • Ryu Bong-Ha;Kim Jin-Sung;Yoon Sang-Hyub;Ryu Ki-Won;Hong Sang-Sun
    • The Journal of Internal Korean Medicine
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    • v.24 no.2
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    • pp.290-299
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    • 2003
  • Background : Nowadays many researches about it s cure are going on world widely since cancer is one of the most human health threatening diseases. In Chinese and North Korean medicine, Duchesnea india(Audra.) Foche. is practically used to treat many kinds of cancer, but in Korea it is rarely used. So, we need to scientifically identify anti-tumor effects of Duchesnea india(Audra.) Foche. Objective : We are aimed to identify anti-tumor effects of Duchesnea india(Audra.) Foche. on the stomach cancer cells through molecular biologic methods. Material & Methods : We used AGS as stomach cancer cells from American Type Culture Collection. We added the boiled extract of Duchesnea india(Audra.) Foche. $5{\mu}l$(Sample I), $10{\mu}l$(Sample II) to cultural media(ml)for 0,6, 12, 24, 48 hours. We measured the killing effect on stomach cancer cells through Tryphan blue exclusion test and the suppressive effect on viability of stomach cancer cells via MTT assay. the quantitative RT-PCR was used to examine their effect on the revelation of Bcl-2, Bcl-XL, and Bax, which are genes related to apoptosis. We measured change of mitochondria membrane permeability and membrane potential via flow cytometry. Result : 1. The killing effect on stomach cancer cells showed that each test groups killed more stomach cancer cells than the control group with a time(6 hours later) and density dependent manner, which was statistical significance. 2. The suppressive effect on viability of stomach cancer cells showed that each test groups had more suppressive effects on viability of stomach cancer cells than the control group with a time(6 hours later), which was statistical significance. 3. In the test about the revelation of genes related to apoptosis, the revelation of Bcl-2 and Bcl-XL decreased with a density manner which was statistical significance. but the revelation of Bax was not changed with statistical significance. 4. As a result of this test, Duchesnea india(Audra.) Foche. caused apoptosis by decreasing the absorbance of mitochondria with statistical significance. and also induced apoptosis by decreasing the membrane potential of mitochondria. Conclusion : This experiment showed that Duchesnea india(Audra.) Foche. has anti-tumor effect with statistical significance. This is in vitro experiment and basic experiment on Duchesnea india(Audra.) Foche. We hope more progressive researchs on Duchesnea india(Audra.) Foche. will go on and its anti-tumor effects will be more practically identified.

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Clinical Experiences of High-Risk Pulmonary Thromboembolism Receiving Extracorporeal Membrane Oxygenation in Single Institution

  • Jang, Joonyong;Koo, So-My;Kim, Ki-Up;Kim, Yang-Ki;Uh, Soo-Taek;Jang, Gae-Eil;Chang, Wonho;Lee, Bo Young
    • Tuberculosis and Respiratory Diseases
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    • v.85 no.3
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    • pp.249-255
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    • 2022
  • Background: The main cause of death in pulmonary embolism (PE) is right-heart failure due to acute pressure overload. In this sense, extracorporeal membrane oxygenation (ECMO) might be useful in maintaining hemodynamic stability and improving organ perfusion. Some previous studies have reported ECMO as a bridge to reperfusion therapy of PE. However, little is known about the patients that benefit from ECMO. Methods: Patients who underwent ECMO due to pulmonary thromboembolism at a single university-affiliated hospital between January 2010 and December 2018 were retrospectively reviewed. Results: During the study period, nine patients received ECMO in high-risk PE. The median age of the patients was 60 years (range, 22-76 years), and six (66.7%) were male. All nine patients had cardiac arrests, of which three occurred outside the hospital. All the patients received mechanical support with veno-arterial ECMO, and the median ECMO duration was 1.1 days (range, 0.2-14.0 days). ECMO with anticoagulation alone was performed in six (66.7%), and ECMO with reperfusion therapy was done in three (33.3%). The 30-day mortality rate was 77.8%. The median time taken from the first cardiac arrest to initiation of ECMO was 31 minutes (range, 30-32 minutes) in survivors (n=2) and 65 minutes (range, 33-482 minutes) in non-survivors (n=7). Conclusion: High-risk PE with cardiac arrest has a high mortality rate despite aggressive management with ECMO and reperfusion therapy. Early decision to start ECMO and its rapid initiation might help save those with cardiac arrest in high-risk PE.