• Title, Summary, Keyword: dynamic reaction cell

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Analysis of Dynamic Performance of Solid Oxide Fuel Cells (고체산화물 연료전지의 동적 성능 특성 해석)

  • Yang, Jin-Sik;Sohn, Jeong-L.;Ro, Sung-Tack
    • Proceedings of the KSME Conference
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    • pp.1652-1657
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    • 2004
  • Model for the dynamic simulation of dynamic behaviors of a solid oxide fuel cell (SOFC) is provided. This model is based upon (1) coupled mass and heat transfer characteristics and (2) important chemical reactions such as electrochemical and reforming reaction in high temperature fuel cells such as SOFC. It is found that the thermal inertia of solid materials in SOFC plays an important role to the dynamic behavior of cell temperature. Dynamic characteristics of cell voltage, power and chemical compositions with different levels of load changes are investigated.

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Inertial Dynamic Effect on the Rates of Diffusion-Controlled Ligand-Receptor Reactions

  • Lee, Woo-Jin;Kim, Ji-Hyun;Lee, Sang-Youb
    • Bulletin of the Korean Chemical Society
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    • v.32 no.spc8
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    • pp.2973-2977
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    • 2011
  • It has been known that the inertial dynamics has a little effect on the reaction rate in solutions. In this work, however, we find that for diffusion-controlled reactions between a ligand and a receptor on the cell surface there is a noticeable inertial dynamic effect on the reaction rate. We estimate the magnitude of the inertial dynamic effect by comparing the approximate analytic results obtained with and without the inertial dynamic effect included. The magnitude of the inertial dynamic effect depends on the friction coefficient of the ligand as well as on the relative scale of the receptor size to the distance traveled by the ligand during its velocity relaxation time.

A Development of Device for Measurement of Vertical Ground Reaction Force(II) (수직 반작용력 측정 장치 개발(II))

  • Park, Jin
    • Korean Journal of Sport Biomechanics
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    • v.13 no.3
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    • pp.341-354
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    • 2003
  • The purpose of this study was to develop the uniaxial force plate system which is measured by the vertical force. The VGRF(vertical ground reaction force) 1.0 was composed of 2 bath digital scales, 2 indicaters, and analyzing software. This system was newly renovated to VGRF 2,0 which are 2 industrial digital scales, 2 adjustable indicators, and enforced analyzing software. Changes of the new system were as follows. First, the height of the plate was 75% lower than before. Second, sensing ability of the load cell was changed from 90 - 0.05kg to 300 - 0.1kg. Third, the speed of data processing was changed from 17 per second to 60 per second. Fourth, analyzing software was enforced to develop and calculate the data. For the test of the system, two different types(bare foot, high-heeled shoes) gait was adopted. highly skilled female walker(23yrs, height 165cm, body mass 46.8kg) participated for the experimental study. During the dynamic performance(gait analysis), the data of each load cell were very similar to the previous studies. Specifically, bare foot walking had less vertical force than high-heeled shoes. Consequently, VGRF 2.0 can sense the general dynamic movements as well as static load conditions.

Research on One Dimensional Dynamic Model in Water Transportation of PEM Fuel Cell

  • Bakhtiar, Agung;You, Jin-Kwang;Park, Jong-Bum;Hong, Boo-Pyo;Choi, Kwang-Hwan
    • 한국태양에너지학회:학술대회논문집
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    • pp.382-387
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    • 2012
  • Water balance has a significant impact on the overall fuel cell system performance. Proper water management should provide an adequate membrane hydration and avoidance of water flooding in the catalyst layer and gas diffusion layer. Considering the important of advanced water management in PEM fuel cell, this study proposes a simple one dimensional water transportation model of PEM fuel cell for use in a dynamic condition. The model has been created by assumption that the output is the water liquid saturation difference. The liquid saturation change is the total difference between the additional water and the removal water on the system. The water addition is obtained from fuel cell reaction and the electro osmotic drag. The water removal is obtained from capillary transport and evaporation process. The result shows that the capillary water transport of low temperature fuel cell is high because the evaporation rate is low.

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Accurate Analysis of Chromium in Foodstuffs by Using Inductively Coupled Plasma Mass Spectrometry with a Collision-Reaction Interface

  • Lee, Seung Ha;Kim, Ji Ae;Choi, Seung Hyeon;Kim, Young Soon;Choi, Dal Woong
    • Bulletin of the Korean Chemical Society
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    • v.34 no.6
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    • pp.1689-1692
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    • 2013
  • Food is a common source of chromium (Cr) exposure. However, it is difficult to analyze Cr in complex food matrices by using inductively coupled plasma mass spectrometry (ICP-MS) because the major isotope, $^{52}Cr$, is masked by interference generated by the sample matrix and the plasma gas. Among the systems available to minimize interference, the recently developed collision-reaction interface (CRI) has a different structure relative to that of other systems (e.g., collision cell technology, octopole reaction system, and dynamic reaction cell) that were designed as a chamber between the skimmer cone and quadrupole. The CRI system introduces collision or reaction gas directly into the plasma region through a modified hole of skimmer cone. We evaluated the use of an CRI ICP-MS system to minimize polyatomic interference of $^{52}Cr$ and $^{53}Cr$ in various foodstuffs. The $^{52}Cr$ concentrations measured in the standard mode were 2-3 times higher than the certified values. This analytical method based on an ICP-MS system equipped with a CRI of helium gas was effective for Cr analysis in complex food matrices.

A Dynamic Simulation Model for the Operating Strategy Study of 1 kW PEMFC (가정용 연료전지 운전 모드 해석을 위한 동특성 모델 개발)

  • Yu, Sang-Seok;Lee, Young-Duk;Hong, Dong-Jin;Ahn, Kook-Young
    • Transactions of the Korean hydrogen and new energy society
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    • v.19 no.4
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    • pp.313-321
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    • 2008
  • Dynamics of the proton exchange membrane fuel cell is specially important when the system is frequently working on transient conditions. Even though the dynamics of proton exchange membrane fuel cell for residential power generation is less critical than that of PEMFC for transportation application, the system dynamics of PEMFC for RPG can be very important for daily start-up and stop. In particular, thermal management of the PEMFC for RPG is very important because the heat generation from electrochemical reaction is delivered to the home for hot water usages. Additionally, the thermal management is also very important for heat balance of the system and temperature control of the fuel cell. The objective of this study is to develop a dynamic system model for the study of PEMFC performance over various BOP options. Basic simulation results will be presented.

Analysis on a Dynamic Model with One Dimension in Water Transportation of PEM Fuel Cell (PEM연료전지의 수분전달에 있어서 1차원 해석을 수행한 동적모델에 관한 연구)

  • Bakhtiar, Agung;Hong, Boo-Pyo;You, Jin-Kwang;Kim, Young-Bok;Yoon, Jung-In;Choi, Kwang-Hwan
    • Journal of the Korean Solar Energy Society
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    • v.32 no.5
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    • pp.118-123
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    • 2012
  • Water balance has a significant impact on the overall fuel cell performance. Maintenance of proper water management should provide an adequate membrane hydration and avoidance of water flooding in the catalyst layer and gas diffusion layer. Considering the important of advanced water management in PEM fuel cell, this study proposes a simple one dimensional water transportation model of PEM fuel cell for use in a dynamic condition. The model has been created by assumption that the output is the water liquid saturation difference. The liquid saturation change is the total difference between the additional water and the removal water on the system. The water addition is obtained from fuel cell reaction and the electro osmotic drag. The water removal is obtained from capillary transport and evaporation process. The result shows that the capillary water transport of low temperature fuel cell is high because the evaporation rate is low.

Dynamic Model of a Passive Air-Breathing Direct Methanol Fuel Cell (수동급기 직접 메탄올 연료전지의 동적 모델)

  • Ha, Seung-Bum;Chang, Ikw-Hang;Cha, Suk-Won
    • 한국신재생에너지학회:학술대회논문집
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    • pp.33-36
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    • 2008
  • The transient behavior of a passive air breathing direct methanol fuel cell (DMFC) operated on vapor-feeding mode is studied in this paper. It generally takes 30 minutes after starting for the cell response to come to its steady-state and the response is sometimes unstable. A mathematical dynamic one-dimensional model for simulating transient response of the DMFC is presented. In this model a DMFC is decomposed into its subsystems using lumped model and divided into five layers, namely the anodic diffusion layer, the anodic catalyst layer, the proton exchange membrane (PEM), the cathodic catalyst layer and the cathodic diffusion layer. All layers are considered to have finite thickness, and within every one of them a set of differential-algebraic governing equations are given to represent multi-components mass balance, such as methanol, water, oxygen and carbon dioxide, charge balance, the electrochemical reaction and mass transport phenomena. A one-dimensional, isothermal and mass transport model is developed that captures the coupling between water generation and transport, oxygen consumption and natural convection. The single cell is supplied by pure methanol vapor from a methanol reservoir at the anode, and the oxygen is supplied via natural air-breathing at the cathode. The water is not supplied from external source because the cell uses the water created at the cathode using water back diffusion through nafion membrane. As a result of simulation strong effects of water transport were found out. The model analysis provides several conclusions. The performance drop after peak point is caused by insufficiency of water at the anode. The excess water at the cathode makes performance recovery impossible. The undesired crossover of the reactant methanol through the PEM causes overpotential at the cathode and limits the feeding methanol concentration.

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Design and Implementation of 150W Portable Fuel Cell Power Pack (150W급 휴대용 연료전지 Power Pack 설계 및 제작)

  • Woo, Dong-Gyun;Joo, Dong-Myoung;Kim, Yun-Sung;Oh, Jae-Gi;Lee, Byoung-Kuk
    • The Transactions of the Korean Institute of Power Electronics
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    • v.17 no.6
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    • pp.553-561
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    • 2012
  • Existing energy sources convert chemical energy into mechanical energy, while fuel cell directly generates electricity through an electrochemical reaction between hydrogen and oxygen. Therefore, it has a lot of strong points such as high efficiency, zero emission, and etc. In addition, with the development of hydrogen preservation technique, some companies have been researching and releasing portable fuel cell power packs for specific applications like military equipment, automobile, and so on. However, there are some drawbacks to the fuel cell, high cost and slow dynamic response. In order to compensate these weak points, auxiliary energy storages could be applied to the fuel cell system. In this paper, the optimum structure for a 150W portable fuel cell power pack with a battery pack is selected considering the specification of the system, and the design process of main parts is described in detail. Here, main objectives are compact size, simple control, high efficiency, and low cost. Then, an automatic mode change algorithm, which converts the operating mode depending on the states of fuel cell stack, battery pack, and load, is introduced. Finally, performance of the designed prototype using the automatic mode change control is verified through experiments.

Application of Dynamic Reaction Cell - Inductively Coupled Plasma Mass Spectrometry for the Determination of Calcium by Isotope Dilution Method (반응셀 유도결합플라스마 질량분석분석기를 이용한 칼슘 동위원소비율의 측정과 동위원소희석법의 적용)

  • Suh, Jungkee;Yim, Yonghyeon;Hwang, Euijin;Lee, Sanghak
    • Analytical Science and Technology
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    • v.15 no.5
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    • pp.417-426
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    • 2002
  • Inductively Coupled Plasma Dynamic Reaction Cell Quadrupole Mass Spectrometry (ICP-DRC-QMS) was characterized for the detection of the six naturally occurring calcium isotopes. The effect of the operating conditions of the DRC system was studied to get the best signal-to-noise ratio. This experiment shows that the potentially interfering ions such as $Ar^+$, ${CO_2}^+$, ${NO_2}^+$, $CNO^+$ at the calcium masses m/z 40, 42, 43, 44 and 48 were removed by flowing $NH_3$ gas at the rate of 0.7 mL/min $NH_3$ as reactive cell gas in the DRC with a RPq value (rejection parameter) of 0.6. The limits of detection for $^{40}Ca$, $^{42}Ca$, $^{43}Ca$, $^{44}Ca$, and $^{48}Ca$ were 1, 29, 169, 34, and 15 pg/mL, respectively. This method was applied to the determination of calcium in synthetic food digest samples (CCQM-P13) provided by LGC for international comparison. The isotope dilution method was used for the determination of calcium in the samples. The uncertainty evaluation was performed according to the ISO/GUM and EURACHEM guidelines. The determined mean concentration and its expanded uncertainty of calcium was ($66.4{\pm}1.2$) mg/kg. In order to assess our method, two reference samples, Riverine Water reference sample (NRCC SLRS-3) and Trace Elements in Water reference sample (NIST SRM 1643d), were analyzed.