• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.529-532
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• 2001

We synthesized polypyrrole (PPy) by electrolysis of the pyrrole monomer solution containing support electrolyte KCl and/or p-toluene sulfonic acid sodium salt (p-TS). The electrochemical behavior was investigated using cyclic voltammetry and AC impedance. In the case of using electrolyte p-TS, the redox potential was about -0.3 V vs. Ag/ AgCl reference electrode, while the potential was about 0 V for using electrolyte KCl. It is considered as the backbone forms a queue effectively by doping p-TS Therefore, it is possible to be arranged regularly. That leads to improvement in the electron hopping. The AC impedance plot gave a hint of betterment of mass transport. PPy doped with p-TS has improved in mass transport, or diffusion. That is because the PPy doped with p-TS has a good orientation, and is more porous than PPy with KCl.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.529-532
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• 2001

We synthesized polypyrrole (PPy) by electrolysis of the pyrrole monomer solution containing support electrolyte KCl and/or p-toluene sulfonic acid sodium salt (p-TS). The electrochemical behavior was investigated using cyclic voltammetry and AC impedance. In the case of using electrolyte p-75, the redox potential was about -0.3 V vs. Ag/AgCl reference electrode, while the potential was about 0 V for using electrolyte KCl. It is considered as the backbone forms a queue effectively by doping p-TS Therefore, it is possible to be arranged regularly. That leads to improvement in the electron hopping. The AC impedance plot gave a tent of betterment of mass transport. PPy doped with p-TS has improved in mass transport, or diffusion. That is because the PPy doped with p-TS has a good orientation, and is more porous than PPy with KCl.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.531-539
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• 2019

The development of cost-effective electrocatalysts with high durability is one of the most important challenges for the commercialization of polymer electrolyte fuel cells (PEFCs). The durability of the electrocatalyst has been studied in terms of structural change in the active metal and the support. In particular, in fuel cell vehicles, degradation of the carbon-based support is known to have a significant effect on the electrocatalyst deterioration since the start-up/shut-down cycle is frequently repeated. The requirements for the support of the electrocatalyst include high surface area, electrical conductivity, chemical stability, and so on. In this study, we propose the evaluation methods for choosing better support materials and present the physicochemical properties that promising carbon supports should have. Three kinds of carbon materials with different crystallinity are compared. From in-depth study using X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and accelerated stress test, it is clearly confirmed that the durability of carbon-supported electrocatalysts is closely related to the physicochemical properties of the carbon supports.

• Journal of the Korean Ceramic Society
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• v.45 no.12
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• pp.796-801
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• 2008

$LaGaO_3$ thin film was prepared on Ni-Fe metal porous substrate by Pulsed Laser Deposition method. By the thermal reduction, the dense $NiO-{Fe_3}{O_4}$ substrate is changed to a porous Ni-Fe metal substrate. The volumetric shrinkage and porosity of the substrate are controlled by the reduction temperature. It was found that a thermal expansion property of the Ni-Fe porous metal substrate is almost the same with that of $LaGaO_3$ based oxide. $LaGaO_3$ based electrolyte films are prepared by the pulsed laser deposition (PLD) method. The film composition is sensitively affected by the deposition temperature. The obtained film is amorphous state after deposition. After post annealing at 1073K in air, the single phase of $LaGaO_3$ perovskite was obtained. Since the thermal expansion coefficient of the film is almost the same with that of LSGM film, the obtained metal support LSGM film cell shows the high tolerance against a thermal shock and after 6 min startup from room temperature, the cell shows the almost theoretical open circuit potential.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.96.2-96.2
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• 2012

고체산화물연료전지(SOFC) cell은 cathode, electrolyte 및 cathode층으로 구성되어져 있는데, 이 cell의 적층은 EVD, CVD, sputtering등의 기상공정과 screen printing, tape casting, dip coating등의 습식 공정으로 제조한다. 적층 공정의 경우 supports의 크기와 형태에 따라 적용에 어려움이 있다. 따라서 본 연구에서는 적층공정의 문제점을 해결코자 전사지를 제조하여 평관형 anode supports 위에 적층하여 cell을 제조하였다. 전사지를 이용한 적층방법은 매우 간단하고 두께와 형상제어가 쉽게 가능하였다. 본 연구를 상세히 언급하면 평관형 anode 지지체를 압출법을 통해 제작하였고, 반소된 지지체 위에 anode function layer와 electrolyte(YSZ)층을 형성한 후 $1400^{\circ}C$ 동시 소결하여 치밀한 전해질 층을 형성하였다. 그 후 cthode층을 형성한 후, $1200^{\circ}C$에서 2시간 소결하여 porous한 전극층을 형성하여 cell을 제작하였다. 그 후 Anode supporter위에 전사지를 이용하여 적층한 경우 cell 소결정도를 SEM으로 관찰하였고, 전기화학특성으로는 출력과 분극저항을 측정하였다. 이를 통해 새로운 구성소재 증착방법 즉 전사지를 이용하는 방법을 개발하였다.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.786-789
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• 2011

In order to estimate the possibility of applying electrolytes generally used in solid oxide fuel cells(SOFCs) to direct carbon fuel cells(DCFCs), properties of YSZ(yttria stabilized zirconia) electrolyte were evaluated. In this study, vacuum slurry coating method was adapted to coat thin layer on anode support substrate. After sintering the electrolyte at $1400^{\circ}C$ for 5hrs, microstructure was analyzed by using SEM image. Also, gas permeability and ionic conductivity were measured to find out the potential possibility of electrolyte for DCFCs. The YSZ electrolyte represented dense coating layer and low gas permeability value. The ionic conductivity of YSZ electrolyte was high over $800^{\circ}C$. After measurement of the electrolyte properties, direct carbon fuel cell was fabricated and its performance was measured at $800^{\circ}C$.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.638-645
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• 2015

Vanadium redox flow batteries (VRFBs) have been investigated for their potential utility as large energy storage systems due to their advantageous performances in terms of long cycle life, high energy efficiency, low cost, and flexible design. Carbon materials are typically used as electrodes in redox reactions and as a liquid electrolyte support. The activities, surface areas, and surface morphologies of porous carbon materials must be optimized to increase the redox flow battery performance. Here, to reduce the resistance in VRFBs, surface-modified carbon felt electrodes were fabricated, and their structural, morphological, and chemical properties were characterized. The surface-modified carbon felt electrode improved the cycling energy efficiencies in the VRFBs, from 65% to 73%, due to the improved wettability with electrolyte. From the results of impedances analysis with proposed fitting model, the electrolyte-coupled polarization in VRFB dramatically decreased upon modification of carbon felt electrode surface. It is also demonstrated that the compressibility of carbon felt electrodes was important to the VRFB polarization, which are concerned with mass transfer polarization. The impedance analysis will be helpful for obtaining better and longer-lived VRFB performances.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.652-655
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• 2009

The bimodal porous carbons were synthesized by using imprinting method with templates of SBA-15 particle and silica sphere and applied as supporting materials for the electro-catalyst of polymer electrolyte fuel cell (PEFC). The silica spheres with diameter size of 100 nm and SBA-15 particle having 200 nm -250 nm diameter and 700 nm -900 nm length were synthesized in this work. The bimodal porous carbons (S100) were prepared by using the silica spheres and SBA-15 as templates and mesophase pitch as a carbon source. The PtRu nanoparticle of ca. 1.9 nm were supported on the bimodal porous carbon support and the resulting PtRu/S100 catalysts was tested by the cyclic voltammetry. The use of bimodal porous carbon showed in comparable electro-catalytic activities with commercial catalyst. Though unclear effects of bimodal porosity of supports could be obtained in the scope of this study, morphological advantage in electrical conductivity can be considered on the electro-catalytic activity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.2
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• pp.141-146
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• 2002

We synthesized polypyrrole (PPy) by electrolysis of the pyrrole monomer solution containing support electrolyte, KCl and/or p-toluene sulfonic acid sodium salt (p-TS). The electrochemical behavior, was investigated using cyclic voltammetry and AC impedance. In the case of using electrolyte p-TS, the oxidation potential of the PPy was about -02 V vs Ag/AgCl reference electrode, while the potential was about 0 V for using electrolyte KCl. The falloff of the oxidation potential gave a sign of an improvement in the electron hopoing mechanism on the backbone. The AC impedance plot gave a hint of betterment of mass transport. PPy doped with p-TS improved in mass transport or diffusion. That was because the PPy doped with p-TS was more porous than PPy with KCl. We attained an effect of good kinetic parameters, in the case of PP-GOx enzyme electrodes doped with p-TS, which were determined by 58 mmol dm$\^$-3/ for apparent Michaelis constant and by 581 ㎂ for maximum current respectively.

• Journal of Nutrition and Health
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• v.35 no.5
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• pp.512-523
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• 2002

The objective of this study was to investigate the nutritional status, biochemical parameters, lipid and electrolytes concentrations of the enteral nutrition patients according to the duration of enteral nutrition. Eighteen neurosurgery patients in the intensive care unit (ICU) at K University Hospital were subjected in this study. The duration of enteral nutrition was classified into under or over six month of period. Anthropometric, biochemical, clinical, and dietary assessments were performed. Patients' intakes of energy and protein were insufficient, from 82% to 95% of their requirements. Mid-arm muscle circumference (MAMC) and mid-am muscle area (MAMA) were significantly lower in patients over six months of enteral nutrition than those in patients under six months. The subjects were malnourished as indicated by nutrition-related parameters such as hemoglobin, albumin, total lymphocyte count (TLC), tricep skinfold thickness (TSF), mid-arm circumference (MAC), MAMC, and MAMA. Serum chloride level of the patients eve, six months of enteral nutrition was lower (94.7 $\pm$ 3.4 mmo1/1) significantly as compared to that of patients (99.3 $\pm$ 3.5 mmol/ 1) under six months. Urinary sodium and chloride levels were lower in the longer time of enteral nutrition patients than those of shorter period of enteral nutrition patients (p < .05). While serum phospholipid level was higher in the patients over six months of enteral nutrition, other blood biochemical parameters and electrolyte concentrations did not show any differences with the duration of enteral nutrition. Neurosurgery patients in the ICU undergoing long-term enteral nutrition tube-feeding were malnourished and had a variety of metabolic complications. The duration of enteral nutrition could affect the patients' nutritional status, biochemical parameters, and electrolytes balance. The patients who require nutritional support over an extended time need the continuous follow-up care and monitoring by the nutrition support team for laboratory, clinical, and nutritional assessments.