• Title, Summary, Keyword: MEA

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Durability of MEA Using sPEEK Membrane Reinforced with Poly Imide in PEMFC (고분자전해질연료전지에서 폴리이미드 강화 sPEEK막 MEA의 내구성)

  • Lee, Hye-Ri;Na, Il-Chai;Oh, Sung-Jun;Park, Kwon-Pil
    • Korean Chemical Engineering Research
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    • v.55 no.3
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    • pp.296-301
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    • 2017
  • Recently, there are many efforts focused on development of more economical non-fluorinated membranes for PEMFCs (Proton Exchange Membrane Fuel Cells). In this study, sulfonated poly (ether ether ketone) (sPEEK) membrane reinforced with poly imide was made to enhance of membrane durability. In order to test durability of single (un-reinforced) membrane and reinforced membrane MEA (Membrane and Electrode Assembly), degradation accelerated stress test was used. Before and after degradation, I-V polarization curve, hydrogen crossover current, electrochemical surface area, membrane resistance and charge transfer resistance were measured. As a result of experiments, hydrogen crossover current of reinforced MEA was lower than that of single MEA, therefor durability of reinforced MEA was higher than that of single MEA. There was not especially short phenomena in reinforced MEA after degradation accelerated stress test.

An Efficient Recursive Cell Architecture for Modified Euclidean Algorithm to Decode Reed-Solomon Code (Reed-Solomon부호의 복호를 위한 수정 유클리드 알고리즘의 효율적인 반복 셀 구조)

  • Kim, Woo-Hyun;Lee, Sang-Seol;Song, Moon-Kyou
    • Journal of the Korean Institute of Telematics and Electronics C
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    • v.36C no.1
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    • pp.34-40
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    • 1999
  • Reed-Solomon(RS) codes have been employed to correct burst errors in applications such as CD-ROM, HDTV, ATM and digital VCRs. For the decoding RS codes, the Berlekamp-Massey algorithm, Euclidean algorithm and modified Euclidean algorithm(MEA) have been developed among which the MEA becomes the most popular decoding scheme. We propose an efficient recursive cell architecture suitable for the MEA. The advantages of the proposed scheme are twofold. First, The proposed architecture uses about 25% less clock cycles required in the MEA operation than[1]. Second, the number of recursive MEA cells can be reduced, when the number of clock cycles spent in the MEA operation is larger than code word length n. thereby buffer requirement for the received words can be reduced. For demonstration, the MEA circurity for (128,124) RS code have been described and the MEA operation is verified through VHDL.

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Durability Evaluation of Stationary PEMFC MEA by OCV Holding Method (정치용 PEMFC MEA의 OCV 유지 방법에 의한 내구 평가)

  • Oh, So-Hydong;Lee, Mihwa;Yun, Jeawon;Lee, Hakju;Kim, Wookwon;Na, Il-Chai;Park, Kwonpil
    • Korean Chemical Engineering Research
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    • v.57 no.3
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    • pp.344-350
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    • 2019
  • Durability is very important for the commercialization of membranes and electrode assemblies (MEA) developed for proton exchange membrane fuel cells (PEMFC). Durability evaluation of stationary PEMFC MEA has a problem that the voltage change rate should be measured for a long time over 1000 hours under constant current conditions. In this study, the electrochemical durability evaluation protocol of membranes (OCV holding method) using to vehicle MEAs was applied to the stationary MEA for the purpose of shortening the durability evaluation time. After operation of the stationary and automobile MEA for 168 hours under conditions of OCV, cathode oxygen, $90^{\circ}C$ and relative humidity of 30%, I-V, LSV, CV, impedance and FER were measured and compared. When the hydrogen permeability, OCV change, ionic conductivity, and fluorine flow rate, which represent the durability of the membrane after degradation, were all examined, it was shown that durability of stationary MEA membrane was better than that of vehicles MEA membrane. In addition, the electrode degradation of stationary MEA was smaller than that of vehicles MEA after degradation operation. It was possible to evaluate in a short time using automotive protocol that the durability of stationary MEA was superior that of vehicle MEA in terms of membrane and the electrode.

Performance Comparison Between Stationary PEMFC MEA and Automobile MEA under Pure Hydrogen Supply Condition (순수 수소 공급조건에서 정치용 PEMFC MEA와 차량용 MEA 성능비교)

  • Oh, Sohyeong;Lee, Mihwa;Lee, Hakju;Kim, Wookwon;Park, Jeong-Woo;Park, Kwonpil
    • Korean Chemical Engineering Research
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    • v.56 no.4
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    • pp.469-473
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    • 2018
  • When pure hydrogen was supplied to the stationary PEMFC generally using the reforming gas, its characteristics were compared with the vehicle PEMFC. The effect of varying the amount of hydrogen supply to the anode on the overall performance was compared. The variation of hydrogen supply in the range of 1.0~1.7 excess (stoi.) had little effect on the OCV of stationary and vehicle MEA (Membrane and Electrode Assembly). At 0.7 V, the current density of the stationary MEA was about 16% higher than that of the vehicle MEA. I-V performance, impedance, and LSV were measured with varying relative humidity. Both OCV and electrolyte membrane resistances decreased with increasing relative humidity. The hydrogen permeability of the stationary MEA was lower than that of the vehicle MEA, showing that the durability of the stationary membrane could be higher than that of the vehicle membrane.

Bacterial Degradation of Monoethanolamine (생물학적 방법에 의한 Monoethanolamine의 분해 연구)

  • Hyun, Jun-Taek;Rhee, In-Hyoung;Kwon, Sung-Hyun;Kim, Dong-Jin;Cho, Dae-Chul
    • KSBB Journal
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    • v.22 no.3
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    • pp.157-161
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    • 2007
  • This study is to investigate the biological degradation and the characteristics of MEA, a pH regulator to be put in the cooling water circulation system for power plants, loading to elevate concentrations of COD and N when eluted into the water environment. MEA, $NH_4^+$ and CODcr were monitored in flask cultures and in a batch aerator. MEA was found to be biologically degradable, producing substantial amount of ammonia (max. 78.1%) in a form of $NH_4^+$ and other carboneous intermediates. The degradation reaction rates were similar one another over all MEA concentrations tested as the activated sludge (microbial consortium) was acclimated to MEA with the gradual and stepwise increase in MEA input into the batch aerator. Also, MLVSS kept increasing with increasing MEA input. The COD-based degradation reaction order was determined to be 1.

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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    • 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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26GHz 40nm CMOS Wideband Variable Gain Amplifier Design for Automotive Radar (차량용 레이더를 위한 26GHz 40nm CMOS 광대역 가변 이득 증폭기 설계)

  • Choi, Han-Woong;Choi, Sun-Kyu;Lee, Eun-Gyu;Lee, Jae-Eun;Lim, Jeong-Taek;Lee, Kyeong-Kyeok;Song, Jae-Hyeok;Kim, Sang-Hyo;Kim, Choul-Young
    • Journal of IKEEE
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    • v.22 no.2
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    • pp.408-412
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    • 2018
  • In this paper, a 26GHz variable gain amplifier fabricated using a 40nm CMOS process is studied. In the case of an automobile radar using 79 GHz, it is advantageous in designing and driving to drive down to a low frequency band or to use a low frequency band before up conversion rather than designing and matching the entire circuit to 79 GHz in terms of frequency characteristics. In the case of a Phased Array System that uses time delay through TTD (True Time Delay) in practice, down conversion to a lower frequency is advantageous in realizing a real time delay and reducing errors. For a VGA (Variable Gain Amplifier) operating in the 26GHz frequency band that is 1/3 of the frequency of 79GHz, VDD : 1V, Bias 0.95V, S11 is designed to be <-9.8dB (Mea. High gain mode) and S22 < (Mea. high gain mode), Gain: 2.69dB (Mea. high gain mode), and P1dB: -15 dBm (Mea. high gain mode). In low gain mode, S11 is <-3.3dB (Mea. Low gain mode), S22 <-8.6dB (Mea. low gain mode), Gain: 0dB (Mea. low gain mode), P1dB: -21dBm (Mea. Low gain mode).

Development of High Performance MEA by Decal Method for PEM Fuel Cell (데칼 공정을 적용한 고성능 MEA 개발)

  • Lee, Ki-Sub;Lee, Jae-Seung;Kwon, Nak-Hyun;Hwang, In-Chul
    • Transactions of the Korean hydrogen and new energy society
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    • v.22 no.5
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    • pp.585-591
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    • 2011
  • This study has focused on the development of high performance membrane-electrode assemblies (MEAs) fabricated by decal method for proton exchange membrane fuel cell (PEMFC). To study the effect of ionomer contents on performance, we fabricated MEAs with several electrodes which were prepared by varying the quantity of ionomer from 20 wt.% to 45 wt.% in catalyst layer. The MEA performance was obtained through single cell test. The MEA prepared from electrode with 25wt.% of ionomer showed the best performance. We evaluated the surface area and pore volume of electrode with BET. We found that the surface area and pore volume in electrode decreased rapidly at the electrode with 40wt.% of ionomer in catalyst layer. MEA was fabricated by roll laminator machine and the roll laminating conditions for the preparation of MEA, such as laminating press, temperature and speed, were optimized. The MEA performance is not affected by laminating temperature and speed, but roll laminating press have a great effect on MEA performance.

Performance of Fuel Cell with PEMFC Fabricated under Different Pressure (고분자 전해질 연료전지 성능에 미치는 MEA 가압제조 공정 조건의 영향)

  • Lee, Ki-Seong;Sim, Sooman;Kim, Dongmin
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.1
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    • pp.70-75
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    • 2013
  • It has fabricated membrane electrode assemblies (MEA) for proton exchange membrane fuel cell by hot-pressing method. The hot-pressing was used for the fabrication of MEA which is composed of commercial platinum electrode on carbon paper. The performance of MEA was studied with different fabrication conditions of temperature, pressure and torque. As the temperature increased, the performance of MEA was increased. and started to decrease l after arrived at the maximum performance of MEA. This is related with good contact between electrode and polymer electrolyte membrane at high temperature and microstructural change at much higher temperature. Similarly, as the pressure increased, the performance of the MEA increased up to highest values and start to decrease. According to the our results, the maximal performance of the MEA was at the temperature of $140^{\circ}C$ and the pressure of $1.5{\times}10^3$ kPa. The optimal torque to assemble the single stack was 3.2 N m.

Characteristics of $CO_2$ Adsorption by MEA Impregnated MCM-41 (MEA가 힘침된 MCM-41 흡착제의 $CO_2$ 흡착 특성)

  • Lee, Jung-Beom;Choi, Sung-Woo
    • Journal of Korean Society of Environmental Engineers
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    • v.33 no.9
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    • pp.686-691
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    • 2011
  • The $CO_2$ adsorption and characteristics of mesoporous silica MCM-41 impregnated by MEA (Monoethanolamine) were examined in this study. The adsorbents were characterized by XRD (X-ray powder diffraction), FT-IR (Fourier transform infrared spectroscopy), $N_2$ adsorption-desorption isotherms. $CO_2$ adsorption measurements were carried out using a GC-TCD unit using 15% $CO_2$ gas. The $CO_2$ adsorption capacity of MCM-41 increased by MEA contents to 10~40 wt%, otherwise MEA content of 50 wt% was decreased $CO_2$ adsorption capacity. The amines tended to deform at MCM-41 surface if too many amines were provided. Therefore $CO_2$ adsorption capacity can be decreased. The results of this study suggest it is important to control content of MEA in MCM-41 for adsorption of $CO_2$.