• Title/Summary/Keyword: Stack

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Effect of stack configuration on the performance of 10W PEMFC stack (10W급 고분자 전해질 연료전지 스택의 구조적 차이에 다른 운전 특성 비교)

  • Yim, Sung-Dae;Kim, Byung-Ju;Sohn, Young-Jun;Yoon, Young-Gi;Yang, Tae-Hyun;Kim, Chang-Soo;Kim, Young-Chai
    • 한국신재생에너지학회:학술대회논문집
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    • pp.286-286
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    • 2009
  • A small PEM fuel cell has two different stack configurations such as active and passive stacks. The active stack has a distintion of high power density although it makes system complex by using alr blower and related BOPs resulting in large system volume. On the contrary, passive stack has an advantage of compact system because it doesn't need air supplying devices although it reveals relatively low stack power density. In this study we fabricated two 10W PEMFC stacks with different stack configurations, active and passive stacks, and tested their performance and stability. The active stack consists of 13cells with an active area of $5cm^2$. The passive stack has 12cells with an active area of $16cm^2$. When we compared the stack performance of those stacks, the active stack showed higher power density compared to the passive stack, particularly at high voltage regions. However, at low voltage and high current regions, the passive stack performance was comparable to the active stack. The stack stability was largely dependent on the fuel humidity, particularly for active stack. At low humidity conditions, the active stack performance was decreased continuously and the cell voltage distribution was not uniform showing seriously low cell voltage at center cells mainly due to the cell drying. The passive stack showed relatively stable behavior at low humidity and the stack performance was largely dependent on the atmospheric conditions.

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THE STACK OF GERBES IN A QUOTIENT STACK

  • Cheong, Daewoong
    • Journal of the Chungcheong Mathematical Society
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    • v.32 no.4
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    • pp.383-391
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    • 2019
  • For a DM stack 𝓧, Chen, Marcus and Úlfarsson ([3]) constructed a stack 𝓖𝓧 of gerbes in 𝓧 that plays a key role in their setting up the theory of very twisted stable maps to 𝓧. This stack is realized as a rigidification of the stack S𝓧 of subgroups of the inertia stack of 𝓧. In this article, we show that when 𝓧 is a quotient stack, the stacks 𝑺𝓧 and 𝓖𝓧 are also quotient stacks.

The Effect of Stack Clamping Pressure on the Performance of a Miniature PEMFC Stack (소형 고분자 연료전지 스택의 체결압력에 따른 성능 특성)

  • Kim, Byung-Ju;Yim, Sung-Dae;Sohn, Young-Jun;Kim, Chang-Soo;Yang, Tae-Hyun;Kim, Young-Chai
    • Transactions of the Korean hydrogen and new energy society
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    • v.20 no.6
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    • pp.499-504
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    • 2009
  • The effect of gas diffusion layer (GDL) compression caused by different stack clamping pressures on fuel cell performance was experimentally studied in a miniature 5-cell proton exchange membrane fuel cell (PEMFC) stack. Three stacks with different GDL compressions, 15%, 35% and 50%, were prepared using SGL 10BC carbon fiber felt GDL and Gore 57 series MEA. The PEMFC stack performance and the stack stability were enhanced with increasing stack clamping pressure resulting in the best performance and stability for the stack with higher GDL compressions up to 50%. The excellent performance of the stack with high GDL compression was mainly due to the reduced contact resistance between GDL and bipolar plate in the stack, while reduced gas permeability of the excessively compressed GDL in the stack hardly affected the stack performance. The high stack clamping pressure also resulted in excessive GDL compression under the rib areas of bipolar plate and large GDL intrusion into the channels of the plate, which reduced the by-pass flow in the channels and increase gas pressure drop in the stack. It seems that these phenomena in the highly compressed stack enhance the water management in the stack and lead to the high stack stability.

Technology of Fuel cell stack fault detection by THDA (전고조파 왜율 분석을 통한 연료전지 스택 고장진단 기술)

  • Kim, UckSoo;Park, HyunSeok;Kang, SunDoo;Eom, JeongYong
    • 한국신재생에너지학회:학술대회논문집
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    • pp.90.1-90.1
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    • 2011
  • This technology is applicable to Electrical vehicle that using Energy from Hydrogen Fueled Cell. Electricity & water is got from chemical reaction between H2 & O2 in stack. This technology is used when fault diagnosis of Fuel cell is needed. It is General method that measure each cell's voltage of stack for fault diagnosis. but, this technology is method of measuring entire voltage of stack. For this reason, fault diagnosis system is simplified and cost of system is lower than previous one. In normal stack condition, characteristic graph of voltage-current has linearity. In fault stack condition, it has non-linearity. we use this characteristic to diagnosis of stack fault. In this technology, Specific frequency current is injected into stack & Stack voltage is measured in response. After that, stack voltage difference is analyzed to diagnosis of stack fault. Presently, Development of current injection module & basic program of THDA is finished. in future we will develop the technology of precise measurement technology about entire stack voltage.

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NEIGHBORHOOD SPACES AND P-STACK CONVERGENCE SPACES

  • Park, Sang-Ho
    • East Asian mathematical journal
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    • v.21 no.1
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    • pp.27-39
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    • 2005
  • We will define p-stack convergence spaces and show that each neighborhood structure is uniquely determined by p-stack convergence structure. Also, we will show that p-stack convergence spaces are a generalization of neighborhood spaces.

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Bidirectional Stack Pointer Network for Korean Dependency Parsing (Bidirectional Stack Pointer Network를 이용한 한국어 의존 파싱)

  • Hong, Seung-Yean;Na, Seung-Hoon;Shin, Jong-Hoon;Kim, Young-Kil
    • Annual Conference on Human and Language Technology
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    • pp.19-22
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    • 2018
  • 본 논문에서는 기존 Stack Pointer Network의 의존 파싱 모델을 확장한 Bi-Stack Pointer Network를 제안한다. Stack Pointer Network는 기존의 Pointer Network에 내부 stack을 만들어 전체 문장을 읽어 dependency tree를 구성한다. stack은 tree의 깊이 우선 탐색을 통해 선정되고 Pointer Network는 stack의 top 단어(head)의 자식(child)을 선택한다. 제안한 모델은 기존의 Stack Pointer Network가 지배소(head)정보로 의존소(child)를 예측하는 부분에 Biaffine attention을 통해 의존소(child)에서 지배소(head)를 예측하는 방향을 추가하여 양방향 예측이 가능하게 한 모델이다. 실험 결과, 제안 Bi-Stack Pointer Network모델은 UAS 91.53%, LAS 90.93%의 성능을 보여주어 기존 최고 성능을 개선시켰다.

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A Study on the Optimization of Fuel-Cell Stack Design (연료 전지 냉각판의 최적 설계)

  • 홍민성;김종민
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.6
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    • pp.92-96
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    • 2003
  • Feul-Cell system consists of fuel reformer, stack and energy translator. Among these parts, stack is a core part which produces electricity directly. In order to set a stack module, fabrication of appropriate stack, design of water flow path in stack and control of coolant are needed. Especially, oater or air is used as a coolant to dissipate heat. The different temperature of each electric cell after cooling affects the performance of the stack. Therefore, it is necessary that the relationship between coolant hearing rate, width of stack, properties of stack, and the shape of water flow path must be understood. For the optimal design, the computational simulation by CFD-ACE has been conducted and the resulting database has been constructed.

An Analysis of the Building Designers and Construction Engineers Understanding about Stack Effect (설문조사를 통한 설계 및 시공 기술자의 연돌현상과 연돌저감방안에 대한 인식 분석)

  • Kang, Tae-Hyuk;Kim, Joo-Young;Song, Doo-Sam
    • Journal of the Architectural Institute of Korea Planning & Design
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    • v.29 no.10
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    • pp.249-257
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    • 2013
  • The purpose of this study is to analyze the understanding of the building designers and construction engineers about stack effect. Even though lots of studies about the problems caused by stack effect have been reported, the stack effect problems are still reported. The countermeasures for stack effect are determined by the building designer and construction engineer in the planning phase and construction phase. However, there are still differences over the selection of the countermeasures between the design team and construction team, which can result in an incomplete countermeasures for stack effect. In this study, the recognitions of the designer and construction engineer for stack effect were analyzed by the questionnaire survey. The differences of recognition for stack effect between the two were analyzed in this paper. This result can be used for determining the countermeasures for stack effect in effect.

Technology Development of Noise Reduction at Stack for Resolution of Abnormal Noise (이상소음 해소를 위한 Stack 소음저감 기술개발)

  • Ho, Kyong-Chan;Lee, Young-Je;Kim, Sung-Jin;Kwon, Hycuk-Kwan;Jung, Hyun-Il
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1049-1052
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    • 2006
  • Object of this study is to develop an Stack Silencer System for quieting abnormal noise around power plant. Abnormal noise gets resident people to feel uncomfortable. Stack Silencer System is to minimize pressure loss of exhaust gas and to maximize noise reduction effect from abnormal noise frequency band. Stack Silencer System is installation in stack and absorbing material is an aluminum foam. Reduction effect measures insertion loss of $8.2{\sim}19.4dB$ by Stack silencer installation. After Stack Silencer System installation, pressure loss of exhaust gas measured $5{\sim}9mmH_2O$.

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Optimization of Fuel-cell stack design using CFD-ACE (CFD-ACE를 이용한 연료 전지 냉각판의 최적 설계)

  • 홍민성;김종민
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.14-18
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    • 2003
  • Feul-cell system consists of fuel reformer, stack and energy translator. Among these parts, slack is a core part which produces electricity directly. In order to set a stack module, fabrication of appropriate stack, design of water flow path in stack, and control of coolant are needed. Especially, water or air is used as a coolant to dissipate heat. The different temperature of each electric cells after cooling and the high temperature of the stack affect the performance of the stack, Therefore, it is necessary that the relationship between coolant, healing rate, width of slack, properties of stack, and the shape of water flow path must be understood. For the optimal design, the computational simulation by CFD-ACE has been conducted and the resulting database has been constructed.

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