• Title/Summary/Keyword: Small stack

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Development of portable DMFC systems (휴대용 직접 메탄올 연료전지 시스템 개발)

  • Moon, Go-Young;Kim, Hyuk;Yoo, Hwang-Chan;Noh, Tae-Geun;Lee, Won-Ho
    • New & Renewable Energy
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    • v.3 no.1 s.9
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    • pp.46-53
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    • 2007
  • Direct Methanol Fuel Cell, DMFC is a potential power source for portable IT application. DMFC works at low temperature ($<100^{\circ}C$) without fuel processing. Methanol has high energy density, fuel economy, and easiness to handle. This paper focuses high efficient catalyst to increase utilization in the electrode, new membrane reducing methanol crossover, new material parts, and optimization of system integration. Lightweight and small-sized DMFC based on new materials, efficient stack, and improved system control will be applied to the 50W prototype system for the notebook computer.

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An Experimental Study on the Performance of PEMFC Stack Depending on Operating Conditions (운전조건에 따른 PEMFC 스택의 성능에 관한 실험적 연구)

  • Lee, Ji-Hong;Lee, Myeong-Yong;Lee, Sang-Seok;Nam, Il-Sang;Lee, Do-Hyung
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.5
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    • pp.770-777
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    • 2009
  • The energy depletion and the environmental pollution like global warming are worldwide issues. For correcting these problems there are many studies on new-renewable energy in Korea. A kind of new-renewable energy, PEMFC(Proton Exchange Membrane Fuel Cell) is a low temperature fuell cell and there are some cases of small craft or submarine adopted PEMFC system in maritime. PEMFC's performance is affected the operating conditions. Finding optimum operating conditions must be performed before adopting PEMFC to system. So in this study, we experiment about various operating conditions to apply 150W PEMFC stack for a model boat. And through the results, we find optimum operating conditions and study an effect of operating conditions to PEMFC.

Protocol Implementations for Web Based Control Systems

  • Shoo Sugoog
    • International Journal of Control, Automation, and Systems
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    • v.3 no.1
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    • pp.122-129
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    • 2005
  • We describe the MiniWeb[7] TCP/IP stack (mIP), which is an extremely small implementation of the TCP/IP protocol suite running 8 or 32-bit micro controllers intended for embedded control systems, and satisfying the subset of RFC1122 requirements needed for host­to-host interoperability over different platforms. Our TCP/IP implementation does sacrifice some of TCP's mechanisms such as fragmentation, urgent data, retransmission, or congestion control. Our implementation is applicable to web based controllers. The network protocols are tested in operational networks using CommView and Dummynet where the various operational parameters such as bandwidth, delay, and queue sizes can be set and controlled.

Influences of Coatings and Solution Corrosivity on Cathodic Protection of Metallic Materials

  • Yoo, Y.R.;Chang, H.Y.;Jin, T.E.;Kim, Y.S.
    • Corrosion Science and Technology
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    • v.5 no.3
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    • pp.106-111
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    • 2006
  • Painting has protected metallic stack but the paint films may be degraded and corrosion problem can be arisen. To protect the painted metal stack, cathodic protection can be applied. If cathodic protection is applied to bare metal, only small area may be protected. However, if cathodic protection is applied to painted metal surface, large area can be protected and the lifetime of paint films can be extended. High corrosion resistant alloys were corroded at a Flue Gas Desulfurization (FGD) facility of power plant within a short period and thus cathodic protection can be used to protect these metals. On the base of computer simulation, if cathodic protection is applied to bare metal in a FGD environment, it was estimated that applied current could almost be spent to protect area near the anode. However, if cathodic protection is applied to high resistant-coated metal, the much larger area from the anode could be effectively protected.

Pixel FPN Characteristics with Color-Filter and Microlens in Small Pixel Generation of CMOS Image Sensor (Color-Filter 및 Microlens를 포함한 CMOS Image Sensor의 Optical Stack 구조 별 Pixel FPN 특성 및 원인 분류)

  • Choi, Woonil;Lee, Hi-Deok
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.11
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    • pp.857-861
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    • 2012
  • FPN (fixed-pattern-noise) mainly comes from the device or pattern mismatches in pixel and color filter, pixel photodiode leakage in CMOS image sensor. In this paper, optical stack module related pixel FPN was investigated and the classification of pixel FPN contribution with the individual optical module process was presented. The methodology and procedure would be helpful in reducing the greater pixel FPN and distinguishing the complex FPN sources with respect to various noise factors.

Design of a combined cartilage graft crusher, morselizer and holder for use in rhinoplasty

  • Rojdmark, Jonas;Cheema, Mubashir
    • Archives of Plastic Surgery
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    • v.46 no.3
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    • pp.282-284
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    • 2019
  • A combined cartilage holder and crusher is described that allows the surgeon to hold, crush, morselize, and suture a single piece or stack of cartilage graft without letting it slip. The customized slit-shaped jaws allow adequate room for the suture needle, while the serrated surfaces hold the cartilage firmly. The use of this instrument is advocated primarily in rhinoplasty for manipulating and suturing a small cartilage graft or a stack of grafts. The use of this instrument may be extended to aesthetic or reconstructive cases where cartilage grafts need to be sutured or shaped, as in eyelid, ear, and nipple reconstruction.

An Out of Core Linear Direct Solution Method for Large Scale Structural Analysis (대규모 구조해석을 위한 보조기억장치 활용 선형 직접해법)

  • Kim, Min-Ki;Kim, Seung Jo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.6
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    • pp.445-452
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    • 2014
  • This paper discusses the multifrontal direct solution method with out of core storage for large scale structural analysis in a limited computing resource. Large scale structural analysis requires huge amount of memory space and computation, so out of core solution method is needed in limited computing resource. In this research, out of core multifrontal solution algorithm which utilize the small size of physical memory and minimize the amount of access of low speed out of core storage is introduced. Three ideas, which are stack space in lower trianglar part of square factorization matrix, inverse stack data structure and selective data caching and recovery by data block size, are proposed.

Development of a Fuel Cell System Model for a Small Ship (소형 선박용 연료전지 시스템 모델 개발)

  • Bang, Eun-Shin;Kim, Young-Min;Kim, Myoung-Hwan;Park, Sang-Kyun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.5
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    • pp.569-575
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    • 2020
  • In this study, a fuel cell system model for ship power was developed and verified by comparing the experimental results obtained by supplying pure oxygen. To verify the proposed model, the fuel cell output characteristics when oxygen was supplied were compared with those when air was supplied using an air compressor. In addition, the effect of the change in the thermal properties of the fuel cell system on the output of the stack was examined. Within the experimental range of this study, when pure oxygen was supplied as the cathode supply gas, the calculated and experimental voltages and outputs obtained through modeling were almost the same over the entire load range. When air was supplied instead of oxygen for the cathode supply at a constant load of 560 A, each stack voltage was approximately 14 V, the stack output was approximately 8 kW, and the stack efficiency was approximately 3 %. It was confirmed that the overall system efficiency was reduced by approximately 8 %. Among the thermal properties examined in this study, the heat transfer coefficient of the coolant to the stack was found to have the greatest effect on the output of the stack.

Design Optimization of a 500W Fuel Cell Stack Weight for Small Robot Applications (소형로봇용 500W급 연료전지 스택무게 최적화 설계)

  • Hwang, S.W.;Choi, G.H.;Park, Sam.;Ench, R. Michael;Bates, Alex M.;Lee, S.C.;Kwon, O.S.;Lee, D.H.
    • Journal of the Korean Solar Energy Society
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    • v.32 no.spc3
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    • pp.275-281
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    • 2012
  • Proton Exchange Membrane Fuel Cells (PEMFC) are the most appropriate for energy source of small robot applications. PEMFC has superior in power density and thermodynamic efficiency as compared with the Direct Methaol Fuel Cell (DMFC). Furthermore, PEMFC has lighter weight and smaller size than DMFC which are very important factors as small robot power system. The most significant factor of mobile robots is weight which relates closely with energy consumption and robot operation. This research tried to find optimum specifications in terms of type, number of cell, active area, cooling method, weight, and size. In order to find optimum 500W PEMFC, six options are designed in this paper and studied to reduce total stack weight by applying new materials and design innovations. However, still remaining problems are thermal management, robot space for energy sources, and soon. For a thermal management, design options need to analysis of Computational Fluid Dynamics (CFD) for determining which option has the improved performance and durability.

A Study on the Vertical Flue Duct for Application of Small Wind Power System in High-Rise Apartments (초고층 공동주택의 소형풍력발전시스템 적용을 위한 수직연도 활용에 관한 연구)

  • Kim, Seong-Yong;Lee, Yong-Ho;Park, Jin-Chul;Hwang, Jung-Ha
    • Journal of the Korean Solar Energy Society
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    • v.31 no.3
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    • pp.116-125
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    • 2011
  • This study examined vertical shafts in high-rise apartments of the old high-rise buildings, reviewed the possibility of using flue ducts, and analyzed airflow patterns according to pressure differences between in and out side of flue ducts through computational fluid dynamics(CFD). The resulting conclusions are as follows: 1) The analysis results of airflow according to the stack effect of flue ducts show that smaller-diameter flue ducts(${\phi}1.2m$) would be morefavorable in increasing downward wind velocity than bigger-diameter ones(${\phi}1.6m$) and that the introduction ducts for outside air should be more than 50% of flue duct diameter to obtain a downward wind velocity higher than $3.0^m/s$ that is the minimum blade wind velocity of a small domestic wind generator. 2) The optimal installation location of a bypass introduction duct is the neutral plane of a flue duct or lower. When the diameter of the upper duct is bigger than that of the lower duct, it will generate more effects on the increase of downward wind velocity in flue ducts.