• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2822-2827
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• 2008

Among the main components of PEM fuel cell, the functions of GDL are to transport reactants from the channel to the catalyst and remove reaction products from the catalyst and transport heat from the catalyst to the channels in the flow filed plate. Permeability of GDL is known to make it possible to enhance the gas transport through GDL, devoting to get better performance. In this paper, three dimensional numerical simulation of the fuel cell by the permeability of GDL is presented by using a FLUENT modified to include the electrochemical behavior. Results show that as permeability is higher than $10^{-12}m^2$, gradients of temperature distribution, oxygen molar concentration and current density distribution in MEA were decreased. Although heat generation was increased as high permeability, MEA's temperature was lower than the low permeability of GDL. This seems because that convection was higher affects in mass and heat transfer process than diffusion as permeability of GDL is increases.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.55.2-55.2
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• 2009

A polymer electrolyte membrane (PEM) fuel cell has been getting large interest as a typical issue in useful applications. The PEMFC is composed of a membrane, catalyst and the bipolar plate. SnOx:F films on SUS316 stainless steel were prepared as a function of substrate with using electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) in order to achieve the corrosion-resistant and low contact resistance bipolar plates for PEM fuel cells. The SnOx:F films coated on SUS316 substrate at surface plasma treatment for excellent stability, before/after heat treatment for good crystalline structure and microwave power for were characterized by X-ray diffraction (XRD), auger electron microscopy (AES) and field emission-scanning electron microscopy (FE-SEM). The SnOx:F film coated on SUS316 substrate with various process parameters were able to observe optimum interfacial contact resistance (ICR) and corrosion resistance. It can be concluded that fluorine-doping content plays an important function in electrical property and characteristic of corrosion-protective film.

• Macromolecular Research
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• v.16 no.4
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• pp.373-378
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• 2008

A simple chemical fixation method for the fabrication of layer-by-layer (LbL) polyelectrolyte multilayer (PEM) has been developed to create a large area, highly uniform film for various applications. PEM of weak poly-electrolytes, i.e., polyallylamine hydrogen chloride (PAH) and poly(acrylic acid)(PAA), was assembled on polymer substrates such as poly(methyl methacrylate)(PMMA) and polycarbonate (PC). In the case of a weak polyelectrolyte, the fabricated thin film thickness of the polyelectrolyte multilayers was strongly dependent on the pH of the processing solution, which enabled the film thickness or optical properties to be controlled. On the other hand, the environmental stability for device application was poor. In this study, we utilized the chemical fixation method using glutaraldehyde (GA)-amine reaction in order to stabilize the polyelectrolyte multilayers. By simple treatment of GA on the PEM film, the inherent morphology was fixed and the adhesion and mechanical strength were improved. Both surface tension and FT-IR measurements supported the chemical cross-linking reaction. The surface property of the polyelectrolyte films was altered and converted from hydrophilic to hydrophobic by chemical modification. The possible application to antireflection coating on PMMA and PC was demonstrated.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.5
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• pp.51-60
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• 2014

To find a practical application approach of polyelectrolyte multilayering (PEM) on inorganic filler, we introduced PEM process without washing step and investigated the effect of shear condition on the washless PEM treatment of ground calcium carbonate (GCC). Washless multilayering on GCC was conducted under various shear conditions such as stirring, homogenization, and ultrasonication. Highly charged polyelectrolytes combination of polydiallyldimethylammonium chloride (PDADMAC) and poly sodium 4-styrene sulfonate (PSS) and low charged polyelectrolytes combination with cationic starch and anionic polyacrylamide (PAM) were compared. In the case of highly charged polyelectrolytes combination, shear conditions did not affect the zeta potential and the particle size of treated GCC. However, the modified GCC particles with low charged polyelectrolytes were more dispersed under higher shear condition while maintaining the zeta potential. In addition, GCC was successfully modified through laboratory inline washless polyelectrolyte multilayering system which consists of homogenizers and pumps.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.67-72
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• 2006

Blower as an air supply system is one of the most important BOP (Balance of Plant) system fur FCV(Fuel Cell Vehicle). For generating and blowing compressed air, the motor of air blower consumes maximum 25% of net power and fuel cell demands a clean air. Considering the efficiency of whole FCV, low friction lubrication of high speed rotor is needed. For the purpose of reducing electrical power and supplying clean air to Fuel cell, oil-free air foil bearings are applied at the each side of brushless motor (BLDC) as journal bearings which diameter is 50mm. The normal power of driving motor has 1.7kW with the 30,000rpm operating range and the flow rate of air has maximum 160 SCFM. The impeller of blower was adopted a mixed type of centrifugal and axial which has several advantages for variable operating condition. The performance of turbo-blower and parameters of air foil bearings was investigated analytically and experimentally. From this study, the performance of the blower was confirmed to be suitable far 80kw PEM FC.

• Advances in Energy Research
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• v.8 no.4
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• pp.203-211
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• 2022

The aim of this paper is to analyze the performance of commercial fuel cell (rated capacity 1000W) with the help of resistive load and output power variation with change in H₂ flow rate and calculate the maximum power point (MPP) of the proton exchange membrane (PEM) while changing AC and DC load respectively. The factors influencing the output power of a fuel cell are hydrogen flow rate, cell temperature, and membrane water content. The results show that when the H₂ flow rate is changed from 11, 13, and 15 Lpm, MPP is increased from lower to higher flow rate. The power of the fuel cell is increased at the rate of 29% by increasing the flow rate from 11 to 15 lpm. This study will allow small-scale industries and residential buildings (in remote or inaccessible areas) to characterize the performance of PEMFC. Furthermore, fuel cell helps in reducing emission in the environment compared to fossil fuels. Also, fuel cells are ecofriendly as well as cost effective and can be the best alternative way to convert energy.

• Journal of the Korea Convergence Society
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• v.7 no.6
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• pp.13-21
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• 2016

In this paper we are trying to explain the effect of temperature on polymer membrane exchange water electrolysis (PEMWE) and polymer membrane exchange fuel cell (PEMFC) simultaneously. A comprehensive studying approach is proposed and applied to a 50Watt PEM fuel cell system in the laboratory. The monitoring process is carried out through wireless LoRa node and gateway network concept. In this experiment, temperature sensor measure the temperature level of electrolyzer, fuel cell stack and $H_2$ storage tank and transmitted the measured value of data to the management control unit (MCU) through the individual node and gateway of each PEMWE and PEMFC. In MCU we can monitor the temperature and its effect on the performance of the fuel cell system and control it to keep the lower heating value to increase the efficiency of the fuel cell system. And we also proposed a mathematical model and operation algorithm for PEMWE and PEMFC. In this model, PEMWE gives higher efficiency at lower heating level where as PEMFC gives higher efficiency at higher heating value. In order to increase the performance of the fuel cell system, we are going to monitor, communicate and control the temperature and pressure of PEMWE and PEMFC by installing these systems in a building of university which is located in the southern part of Korea.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.953-958
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• 2008

The object of this study was to investigate the immune-enhancing effects of Chlorella vulgaris (CV) on a deteriorated immune function by a protein-energy malnutrition (PEM) diet. Unicellular algae, CV were used as a biological response modifier. Male C57BL/6J mice were fed for 15 days with standard diet or a PEM diet, which is associated with decreased host immune defense. After 8 days, mice in the PEM diet group were orally administered by 0.05, 0.1, and 0.15 g/kg body weight of CV or distilled water. Nutritional parameters, and interferon (IFN)-$\gamma$ levels were significantly increased in the blood serum of the CV (0.15 g/kg)-treated group (29.6$\pm$2.8 pg/mL) compared to the non-treated PEM group (4.1$\pm$0.4 pg/mL, p<0.05). In addition, cell proliferation and production of cytokines were investigated via a CV (0.01, 0.1, and 1 mg/mL) treatment using a human T cell line MOLT-4 cell. The CV treatment (1 mg/mL) significantly increased the production of both IFN-$\gamma$ and interleukin (IL)-2 (51.3$\pm$3.4 and 285.9$\pm$18.8 pg/mL, respectively) compared to the control (51.3$\pm$3.4 and 442.6$\pm$14.3 pg/mL, respectively), but did not affect the production of IL-4. These results suggest that CV may be useful in improving the immune function.

• Food Science of Animal Resources
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• v.24 no.2
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• pp.146-150
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• 2004

The objectives of this study were to develope the uncooked-restructured belly (URB) and the processed-restructured bacon (PRB) using a protein-emulsion material (PEM) from pork, and to evaluate the quality characteristics of the URB and PRB. The PEM used to adhere muscle and fat tissues was prepared with a salt-soluble protein and emulsions (ratio 9:1). In color measurements, L$\^$*/, a$\^$*/ and b$\^$*/ values were significantly (p＜0.05) higher in URB than PRB. There was no significant difference in L$\^$*/ value between PRB from fresh pork and PRB from thaw pork PRB showed significantly (p＜0.05) higher water holding capacity compared to URB. Tensil strength of PRB was also significantly (p＜0.05) higher than that of URB. However, PRB from thawed pork marked the lowest color score among restructured meats in sensory evaluation. The scores of juiciness and tenderness were significantly (p＜0.05) Higher in URB compared to PRB. Consequently URB had significantly (p.＜0.05) higher score of overall acceptability than PRB. These results suggested that URB made with PEM could have a better sensory characteristics compared to PRB. Results also suggested that the PEM would not be enough to adhere fresh muscle and fat tissues as much as PRB, even though the possibility of PEM was confirmed as a meat glue.

• Journal of Hydrogen and New Energy
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• v.19 no.1
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• pp.18-25
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• 2008

The membrane electrode assembly(MEA) was prepared by a nonequilibrium impregnation- reduction (I-R) method. Nafion 117 and covalently cross-linked sulfonated polyetherether with tungsto- phosphoric acid (CL-SPEEK/TPA30) prepared by our laboratory, were chosen as polymer electrolyte membrane(PEM). $Pt(NH_3)_4Cl_2$, $RuCl_3$ and reducing agent $(NaBH_4)$ were used as electrocatalytic materials. Electrochemical activity surface area(ESA) and specific surface area(SSA) of Pt cathodic electrode with Nafion 117 were $22.48m^2/g$ and $23.50m^2/g$ respectively under the condition of 0.8 M $NaBH_4$. But Pt electrode prepared by CL-SPEEK/TPA30 membrane exhibited higher ESA $23.46m^2/g$ than that of Nafion 117. In case of Pt-Ru anodic electrode, the higher concentration of Ru was, the lower potential of oxygen reduction and region of hydrogen desorption was, and Pt-Ru electrode using 10 mM $RuCl_3$ showed best properties of SSA $34.09m^2/g$ with Nafion 117. In water electrolysis performance, the cell voltage of Pt/PEM/Pt-Ru MEA with Nafion 117 showed cell property of 1.75 V at $1A/cm^2$ and $80{\circ}C$. On the same condition, the cell voltage with CL-SPEEK/TPA30 was the best of 1.73 V at $1A/cm^2$.