• Title/Summary/Keyword: $CO_2$ leakage

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Prevention of Oil Contamination in the Excitation System of a Power Plant Generator (발전용 발전기 여자설비의 오일 오염방지)

  • Choi, Jae-Gyu;Yoo, Ho-Seon;Moon, Seung-Jae
    • Plant Journal
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    • v.7 no.2
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    • pp.30-38
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    • 2011
  • The purpose of this paper is to review the understanding of pollution causes in the excitation system and how to solve the problem. The cause of the problem was in-leakage of bearing lubricant oil through the gap between rotor and outer in the air deflector, which was triggered by a negative pressure with respect to the operation of a collector ring fan in the collector house. In order to prevent exciting current transmission equipment pollutant, the reduction of the negative gage pressure of the inside of collector house is required. The protection in-leakage of bearing lubricant oil through the gap between rotor and outer of the air deflector are necessary. The reduction of the inside diameter of air deflector and the expansion of inlet filter of collector house are inevitable.

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Development of an Architecture Monitoring System Using Wireless Sensor Network (무선 센서네트워크를 이용한 건축물 모니터링 시스템 구현)

  • Chang, Hyung-Jun;Kim, Beom-Soo;Kong, Young-Bae;Park, Gwi-Tae;Shim, II-Joo
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.6
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    • pp.568-573
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    • 2007
  • Environmental information (temperature, humidity, vibration, $CO_2$, gas leakage, etc.) of building is an essential item to manage and monitor a building. For intelligent building, it is necessary to get temperature and illumination information to save energy and crack information to prevent structural problems. Moreover, temperature and gas leakage information to alarm a tire precaution, or humidity information to maintain comfortable environment. However, there have not been many researches on systems for gathering environmental information and building maintenance due to high costs. In this paper, wireless sensor network technology is applied to collecting building environmental information. Wireless sensor network is one of the latest issues and has low-power consumption, low-cost, self-configuration features.

Effect Assessment and Derivation of Ecological Effect Guideline on CO2-Induced Acidification for Marine Organisms (이산화탄소 증가로 인한 해수 산성화가 해양생물에 미치는 영향평가 및 생태영향기준 도출)

  • Gim, Byeong-Mo;Choi, Tae Seob;Lee, Jung-Suk;Park, Young-Gyu;Kang, Seong-Gil;Jeon, Ei-Chan
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.17 no.2
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    • pp.153-165
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    • 2014
  • Carbon dioxide capture and storage (CCS) technology is recognizing one of method responding the climate change with reduction of carbon dioxide in atmosphere. In Korea, due to its geological characteristics, sub-seabed geological $CO_2$ storage is regarded as more practical approach than on-land storage under the goal of its deployment. However, concerns on potential $CO_2$ leakage and relevant acidification issue in the marine environment can be an important subject in recently increasing sub-seabed geological $CO_2$ storage sites. In the present study effect data from literatures were collected in order to conduct an effect assessment of elevated $CO_2$ levels in marine environments using a species sensitivity distribution (SSD) various marine organisms such as microbe, crustacean, echinoderm, mollusc and fish. Results from literatures using domestic species were compared to those from foreign literatures to evaluate the reliability of the effect levels of each biological group and end-point. Ecological effect guidelines through estimating level of pH variation (${\delta}pH$) to adversely affect 5 and 50% of tested organisms, HC5 and HC50, were determined using SSD of marine organisms exposed to the $CO_2$-induced acidification. Estimated HC5 as ${\delta}pH$ of 0.137 can be used as only interim quality guideline possibly with adequate assessment factor. In the future, the current interim guideline as HC5 of ${\delta}pH$ in this study will look forward to compensate with supplement of ecotoxicological data reflecting various trophic levels and indigenous species.

Optimal Conditions of Co-Immobilized Mixed Culture System with Aspergillus awamori and Zymomonas mobilis (Aspergillus awamori와 Zymomonas mobilis로 구성된 혼합고정화 배양계의 최적 조건)

  • 박석규;이상원;손봉수;최수철;서권일;성낙계;김홍출
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.24 no.5
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    • pp.803-810
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    • 1995
  • Co-immobilized mixed culture system(A-Z system) composed of two different oxygen-demanding strains, aerobic(Aspergillus awamori) and anaerobic(Zymomonas mobilis) strains, in a Ca-alginate gel beads was developed to increase ethanol production from raw starch as a carbon source. Optimal mixture ratio of A. awamori and Z. mobilis was $1.25{\times}10^{9}\;spores/L-gel$ and 0.5g cells/L-gel, respectively. After 120 hours of cultivation, gel beads distinguished oxygen-rich surface for A. awamori from oxygen-deficient central part for Z. mobilis. At A-Z culture system, yield of ethanol on glucose, $Y_{p/s}=0.18$, was very low and there was high leakage of cells from surface of gel beads. At A-Z 36 cultrue system with changing silicon check valve for cotton plug at 36 hours in A-Z culture system, there was no cell leakage from gel beads, pH was maintained at around 4.3 during cultivation, and yield of ethanol on glucose, $Y_{p/s}=0.36$, showed 2 times higher than that of control culture system(cotton plug culture).

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Structural and Electrical Properties of BiFeO3 Thin Films by Eu and V Co-Doping (Eu와 V 동시 도핑에 의한 BiFeO3 박막의 구조와 전기적 특성)

  • Chang, Sung-Keun;Kim, Youn-Jang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.3
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    • pp.229-233
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    • 2019
  • Pure $BiFeO_3$ (BFO) and (Eu, V) co-doped $Bi_{0.9}Eu_{0.1}Fe_{0.975}V_{0.025}O_{3+{\delta}}$ (BEFVO) thin films were deposited on $Pt(111)/Ti/SiO_2/Si(100)$ substrates by chemical solution deposition. The effects of co-doping were observed by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The electrical properties of the BEFVO thin film were improved as compared to those of the pure BFO thin film. The remnant polarization ($2P_r$) of the BEFVO thin film was approximately $26{\mu}C/cm^2$ at a maximum electric field of 1,190 kV/cm with a frequency of 1 kHz. The leakage current density of the co-doped BEFVO thin film ($4.81{\times}10^{-5}A/cm^2$ at 100 kV/cm) was two orders of magnitude lower than of that of the pure BFO thin film.

Improvement of Reliance on Zinc oxide (ZnO Varistor의 신뢰성 향상)

  • Cho, Hyun-Moo;Lee, Sung-Gap
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.110-113
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    • 2004
  • ZnO varistor ceramics which were fabricated with variation of added of $0.5{\sim}1.0mol%\;Co_3O_4$ sintered at $1150^{\circ}C$. In the specimen added $0.7mol%\;Co_3O_4$, sintered density was $6.03g/cm^3$ and electrical peoperties were superior to any other components. The nonlinear coefficient a was 83, and clamping voltage ratio was 1.35. But, endurence surge current in the specimen added $0.5mol%\;Co_3O_4$ was $7000A/cm^2$, and deviation of varistor voltage was ${\Delta}-3.23%$. As P.C.T and T.C.T environment test were succeed in all specimens, and deviation of varistor voltage in the specimen added $0.6mol%\;Co_3O_4$ was ${\Delta}-0.81%$. All specimens showed a good leakage current property in the High Temperature Continuous Load Test for 1000hr, at $85^{\circ}C$, and variation rate of the varistor voltage was ${\Delta}-2%$.

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Effect of Sintering Temperature on Electrical Stability against Surge Stress of Zn-Pr-Co-Cr-Er Oxides-based Varistors (Zn-Pr-Co-Cr-Er 산화물계 바리스터의 써지 스트레스에 대한 전기적 안정성에 미치는 소결온도의 영향)

  • Nahm, Choon-Woo;Park, Jong-Ah;Yoo, Dea-Hoon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.11
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    • pp.1167-1173
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    • 2004
  • This paper reports the variations of varistor voltage, nonlinear exponent, leakage current, and dissipation factor against surge stress of ZnO-P $r_{6}$ $O_{11}$-CoO-C $r_2$ $O_3$-E $r_2$ $O_3$(ZPCCE)-based varistors manufactured with the variations of sintering temperature. It was found that the variations of electrical parameters against surge stressing current of 100 A/$\textrm{cm}^2$(8x20 ${\mu}\textrm{s}$) is not so large under the surge stress of 700 times. Among varistors, specially the varistor sintered at 134$0^{\circ}C$ exhibited the smallest variations, with %$\Delta$ $V_{lmA}$=+0.23%, %$\Delta$$\alpha$=+0.23%, %$\Delta$ $I_{L}$=0%, %$\Delta$tan$\delta$=-6.94%. The clamping voltage ratio( $V_{c}$/ $V_{lmA}$) of all varistors was less than 2.2.2.2.2.2.2.

Preparation and Oxygen Permeability of $PrBa_{0.9}Sr_{0.1}Co_2O_{5+{\delta}}$ Ceramic Membrane ($PrBa_{0.9}Sr_{0.1}Co_2O_{5+{\delta}}$ 세라믹 분리막의 제조 및 산소투과 특성)

  • Pyo, Dae-Woong;Kim, Jong-Pyo;Son, Su-Hwan;Park, Jung-Hoon
    • Membrane Journal
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    • v.21 no.4
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    • pp.321-328
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    • 2011
  • $PrBa_{0.9}Sr_{0.1}Co_2O_{5+{\delta}}$ oxide was synthesized by soild state reaction method. Dense ceramic membrane was prepared using as-prepared powder by pressing and sintering at $1250^{\circ}C$. XRD result of membrane showed double perovskite structure. Leakage and oxygen permeation test were conducted on the membrane sealed by pyrex ring as a sealing material. Oxygen permeation was measured in the temperature range from 850 to $950^{\circ}C$. The oxygen flux of $PrBa_{0.9}Sr_{0.1}Co_2O_{5+{\delta}}$ membrane was increased with the temperature from 0.15 to $0.32mL/cm^2{\cdot}min$.

DC Accelerated Aging Characteristics of $Pr_{6}O_{11}$-Based ZnO Varistors with CoO Content (CoO 첨가량에 따른 $Pr_{6}O_{11}$계 ZnO 바리스터의 DC 가속열화특성)

  • Kim, Hyang-Suk;Jung, Young-Chul;Nahm, Choon-Woo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.467-471
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    • 2001
  • DC accelerated aging characteristics of $Pr_{6}O_{11}$-based ZnO varistors, which are composed of $ZnO+Pr_{6}O_{11}+CoO+Cr_{2}O_{3}+Dy_{2}O_{3}$ ceramics were investigated with CoO content in the range of 0.5 - 5.0 mol%. The varistors doped with 1.0 mol% revealing maximum value(66.61) in the nonlinear exponent exhibited excellent stability, in which the variation rates of the varistor voltage, the nonlinear exponent and leakage current are -1.93%, -10.48%, and +288.79%, respectively, under DC accelerated aging stress, such as $(0.85V_{lmA}/115^{\circ}C/24h)+(0.90V_{lmA}120^{\circ}C/24h)+(0.95V_{lmA}/125^{\circ}C/24h)+(0.95V_{lmA}/150^{\circ}C/24h)$. Next the varistors doped with 2.0 mol% exhibiting the nonlinear exponent of 47.39 showed high stability.

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DC Accelerated Aging Characteristics of $Pr_{8}O_{11}$-Based ZnO Varistors with CoO Content (CoO 첨가량에 따른 $Pr_{8}O_{11}$계 ZnO 바리스터의 DC 가속열화특성)

  • 김향숙;정영철;남춘우
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11a
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    • pp.467-471
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    • 2001
  • DC accelerated aging characteristics of Pr$_{6}$O$_{11}$-based ZnO varistors, which are composed of ZnO+Pr$_{6}$O$_{11}$+CoO+Cr$_2$O$_3$+Dy$_2$O$_3$ ceramics were investigated with CoO content in the range of 0.5~5.0 mol%. The varistors doped with 1.0 mol% revealing maximum value(66.61) in the nonlinear exponent exhibited excellent stability, in which the variation rates of the varistor voltage, the nonlinear exponent and leakage current are -1.93%, -10.48%, and 288.79%, respectively, under DC accelerated aging stress, such as (0.85 V$_{1mA}$/115$^{\circ}C$/24h)+(0.90 V$_{1mA}$/12$0^{\circ}C$/24h)+(0.95 V$_{1mA}$/1$25^{\circ}C$/24h)+(0.95 V$_{1mA}$/15$0^{\circ}C$/24h). Next the varistors doped with 2.0 mol% exhibiting the nonlinear exponent of 47.39 showed high stability,ity,ability,ity,

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