• Animal Systematics, Evolution and Diversity
• /
• v.24 no.1
• /
• pp.143-145
• /
• 2008

The first known males of the spider Alloclubionoides ovatus (Paik, 1976) from Korea are described with detailed illustrations, spination of each leg and trichobothrium patterns. Males have a large conductor expanded curvedly 'p'-shaped with thin membrane of distal end surrounded the linear embolus and slender embolus penetrating tegulum.

• Journal of Chest Surgery
• /
• v.20 no.3
• /
• pp.451-457
• /
• 1987

Reoperations following cardiac surgery have an increased risk of the danger of damaging the heart, great vessels or extracardiac grafts because of adhesions to the sternum. We experimentally evaluated 3 different methods for pericardial closure. A standardized procedure for induction of pericardial adhesions was carried out in 30 rabbits. For closure of pericardium, animals were divided into 3 groups, 10 animals respectively: Croup 1 [simple pericardial closure]The pericardium was primarily resuture; Group 2 [Core-Tex surgical membrane as a pericardial substitute]- A Gore-Tex surgical membrane was interposed between the sternum and the heart; and Group 3 [pericardial tension releasing technique]-Three longitudinal overlapping incisions were made on the right side of the pericardium while the midline incison was sutured. Animals were put to death 4 weeks postoperatively and the pericardial space was examined for pericardial adhesions and epicardial reactions. The extent of adhesions and reactions were graded as: I-none; II-minimal; III-moderate; and IV-severe. Histologic studies of the pericardium, the pericardial substitute and the epicardium were also performed. The results were as follows: 1. In group 1 [simple pericardial closure], the degree of pericardial adhesions were grade I in 1 animal, grade II in 2, grade III in 4 and grade IV in 3. Epicardial reactions were grade I in 1 animal, grade II in 3, grade III in 5 and grade IV in 1. Histologic examination revealed thick fibrous tissue that obliterated the pericardial space in 7 animals. 2. In group 2 [Gore-Tex surgical membrane as a pericardial substitute], the degree of pericardial adhesions were grade I in 3 animals, grade II in 3, grade III in 2 and grade IV in 2. The degree of epicardial reactions were grade II in 1 animal, grade III in 5 and grade IV in 4. Histologic studies revealed a thin layer of dense fibrous tissue which covered the Gore-Tex surgical membrane and thick loose fibrous tissue on the epicardium just beneath the substitute. 3. In group 3 [pericardial tension releasing technique], the degree of pericardial adhesions were grade I in 3 animals, grade II in 4, grade III in 2 and grade IV in 1. The degree of epicardial reactions were grade 1 in 4 animals, grade II in 4 and grade III in 2. Severe epicardial reactions were not observed in this group. Histologic examination showed normal epicardium in 4 animals and the epicardium of the other 6 animals only revealed very thin fibrous layer compared to group I and group II. Pericardial adhesions more than grade III were 70% in group 1, 40% in group 2 and 30% in group 3. Pericardial adhesions were reduced in group 2 and group 3 compared to group 1, but statistically not significant. Epicardial reactions more than grade III were 60% in group 1, 90% in group 2 and 20% in group 3. Epicardial reactions were significantly reduced in group 3 compared to group 2. Author`s modified pericardial releasing technique provides marked augment of pericardial surface area and facilitates tension-free pericardial closure. Furthermore, pericardial adhesion and epicardial reaction will be reduced with the pericardial tension releasing technique.

• Membrane Journal
• /
• v.6 no.3
• /
• pp.173-181
• /
• 1996

Common volatile organic compounds(VOCs) such as toluene and methanol were removed successfully from N$_{2}$ using a novel silicone-coated hollow fiber membrane module. This novel membrane is a thin film composite(TFC) and was highly efficient in removing VOCs selectively from a N$_{2}$ stream. This membrane had some innate advantages over other silicone-based membrane in that the selective barrier was ultrathin(~1 $\mu$m) and the porosity of the polypropylene substrate was high which leads to a low permeation resistance. The substram was very strongly bonded to the coating layer by plasma polymerization and can withstand a very high pressure. A small hollow fiber module having a length of 25cm and 50 fibers could remove 96~99% of toluene as well as methanol vapors when the feed flow rate was up to 60cc/min. The percent removal of VOCs were even higher when the feed inlet concentration was higher. This process is especially suitable for treating streams having a low flow rate and high VOCs concentration. The permeances of VOCs through this membrane was in the range of $4~30 \times 10^{-9}gmol/sec \cdot cm^{2}\cdot cmHg$ for both toluene and methanol, and nitrogen permeance was between $3~9 \times 10^{-10}gmol/sec \cdot cm^{2} \cdot cmHg$. High separation factor between 10~55 for toluene/N$_{2}$ and 15~125 for methanol/N$_{2}$ were obtained depending on the feed flow rate ranges and feed VOCs concentration levels.

• Membrane Journal
• /
• v.20 no.4
• /
• pp.312-319
• /
• 2010

Carbon membrane materials have received considerable attention for the gas separation including hydrocarbon mixture of ingredients of the volatile organic compounds(VOCs) because they possess their higher selectivity, permeability, and thermal stability than the polymeric membranes. The use of activated carbon membranes makes it possible to separate continuously the VOCs mixture by the selective adsorption-diffusion mechanism which the condensable components are preferentially adsorbed in to the micropores of the membrane. The activated carbon hollow fiber membranes with uniform adsorptive micropores on the wall of open pores and the surface of the membranes have been fabricated by the carbonization of a thin film of phenolic resin deposited on porous alumina hollow fiber membrane. Oxidation, carbonization, and activation processing variables were controlled under different conditions in order to improve the separation characteristics of the activated carbon membrane. Properties of activated carbon hollow fiber membranes and the characterization of a gas permeation by pyrolysis conditions were studied. As the result, the activated carbon hollow fiber membranes with good separation capabilities by the molecular size mechanism as well as selective adsorption on the pores surface followed by surface diffusion effective in the recovery hydrocarbons have been obtained. Therefore, these activated carbon membranes prepared in this study are shown as promising candidate membrane for separation of VOCs.

• Membrane Journal
• /
• v.33 no.6
• /
• pp.427-438
• /
• 2023

In this study, in order to improve the performance of the reverse osmosis membrane with high water flux and high salt rejection, a study was conducted on the evaluation of characteristics according to the curing temperature and time during various additives and interfacial polymerization. The morphology of the membrane with no additives and the membrane with additives both showed a "rigid-and-valley" structure, confirming that the polyamide layer was successfully polymerized on the surface of the porous support layer. In addition, the additive of 2-Ethyl-1,3-hexanediol (EHD) had improved hydrophilicity and water flux, which was confirmed by measuring the contact angle. Finally, a highly permeable TFC membrane with NaCl and MgSO₄ salt rejection of 97.78% and 98.7% and a high water flux of 3.31 L/(m²⋅h⋅bar) was prepared.

• Journal of Korean Association for Spatial Structures
• /
• v.11 no.3
• /
• pp.115-123
• /
• 2011

It is needed to investigate the material properties of ETFE foil under various temperatures because ETFE membrane foils have very thin depth and relatively high flexibility. In this paper, the material properties of ETFE membrane foil obtained from 3 testes under various temperatures are presented. First, the uniaxial test under four temperatures as -20$^{\circ}C$, 0$^{\circ}C$, +20$^{\circ}C$ and +40$^{\circ}C$ was performed. Each 5 specimen was tested and the yield stress, tensile strength and the Young's modulus of the foils are obtained. Second, the creep testes under three temperatures as 25$^{\circ}C$, 40$^{\circ}C$ and 60$^{\circ}C$, 3MP, 6MP and 9MP tension load was subjected to the specimen and the creep characteristics was investigated. Finally, the tear test under $5^{\circ}C$, $^0{\circ}C$ and $20^{\circ}C$ was performed. It is concluded that the shape of stress-strain curve or general behaviors are similar with that of normal temperatures but the mechanical characteristics of ETFE membrane foils were affected by the temperatures, obviously.

• Journal of Hydrogen and New Energy
• /
• v.21 no.4
• /
• pp.271-277
• /
• 2010

$(Ba(Zr_{0.85}Y_{0.15})O_{3-\delta})$ oxide, showing high protonic conductivity at high temperatures and good chemical stability with $CO_2$ are referred to as hydrogen separation membrane. For high efficiency of hydrogen separation ($H_2$ flux and selectivity) and low fabrication cost, ultimate thin and dense BZY-Ni layer has to be coated on a porous substrate such as $ZrO_2$. Aerosol depostion (AD) process is a novel technique to grow ceramic film with high density and nano-crystal structure at room-temperature, and may be applicable to the fabrication process of AD integration ceramic layer effectively. XRD, SEM, X-ray mapping measurements were conducted in order to analyze the characteristics of BZY-Ni membrane fabricated by AD process. it is observed that it is homogeneous distribution for BZY-Ni. The result of $H_2$ permeation rate suggests that BZY-Ni composite is higher than BZY.

• Journal of Sensor Science and Technology
• /
• v.9 no.3
• /
• pp.177-181
• /
• 2000

The tunneling current is exponentially dependent on the separation gap between a pair of conductors. The detection of displacement can be, therefore, carried out by measurment of a variation in the tunneling current. In this experiment, we fabricated pyramid-type silicon tunneling devices in which a tunneling current flow between a micro-tip and $Si_3N_4$ thin film membrane. A MEMS process was used for the fabrication of the tunneling devices. The micro-tips were formed on Si wafers by undercutting a differently oriented square of $SiO_2$ with KOH. The stiffness of the $Si_3N_4$ films were observed and the model for the stiffness calculation, which is useful in predicting the stiffness even when the stiffness ranges beyond the scope of the normal experimental condition, was suggested.

• New & Renewable Energy
• /
• v.6 no.1
• /
• pp.46-52
• /
• 2010

Membrane electrode assemblies (MEAs) for proton exchange membrane fuel cells (PEMFCs) have been extensively studied to improve their initial performance as well as their durability and to facilitate the commercialization of fuel cell technology. To improve the MEA performance, particularly at low Pt loadings, many approaches have been made. In the present study, MEA performance improvement was performed by adding $TiO_2$ particles into the catalyst layer of MEA. Most of previous studies have focused on the MEA performance enhancement under low humidity conditions by adding metal oxides into the catalyst layer mainly due to the water keeping ability of those metal oxides particles such as $Al_2O_3$, $SiO_2$ and zeolites. However, this study mainly focused on the improvement of MEA performance under fully humidified normal conditions. In this study, the MEA was prepared by decal method aiming for a continuous MEA fabrication process. The decal process can make very thin and uniform catalyst layer on the surface of electrolyte membrane resulting in very low interfacial resistance between catalyst layer and the membrane surface and uniform electrode structure in the MEA. It was found that the addition of $TiO_2$ particles into the catalyst layer made by decal method can minimize water flooding in the catalyst layer, resulting in the improvement of MEA performance.

• Korean Journal of Materials Research
• /
• v.20 no.4
• /
• pp.187-193
• /
• 2010

Chromium nitride (CrN) samples with two different layer structures (multilayer and single layer) were coated on bipolar plates of polymer electrolyte membrane fuel cells (PEMFC) using the reactive sputtering method. The effects with respect to layer structure on corrosion resistance and overall cell performance were investigated. A continuous and thin chromium nitride layer ($Cr_{0.48}\;N_{0.52}$) was formed on the surface of the SUS 316L when the nitrogen flow rate was 10 sccm. The electrochemical stability of the coated layers was examined using the potentiodynamic and potentiostatic methods in the simulated corrosive circumstances of the PEMFC under $80^{\circ}C$. Interfacial contact resistance (ICR) between the CrN coated sample and the gas diffusion layer was measured by using Wang's method. A single cell performance test was also conducted. The test results showed that CrN coated SUS316L with multilayer structure had excellent corrosion resistance compared to single layer structures and single cell performance results with $25\;cm^2$ in effective area also showed the same tendency. The difference of the electrochemical properties between the single and multilayer samples was attributed to the Cr interlayer layer, which improved the corrosion resistance. Because the coating layer was damaged by pinholes, the Cr layer prevented the penetration of corrosive media into the substrate. Therefore, the CrN with a multilayer structure is an effective coating method to increase the corrosion resistance and to decrease the ICR for metallic bipolar plates in PEMFC.