• Title/Summary/Keyword: high temperature high pressure

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Assessment of SCDAP Using the Full-Length High-Temperature FLHT-2 Test (FLHT-2 실험결과를 이용한 SCDAP코드 평가)

  • Park, Choon-Kyung;Park, Jong-Hwa;Yoo, Kun-Jung;Chae, Sung-Ki
    • Nuclear Engineering and Technology
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    • v.20 no.1
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    • pp.54-64
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    • 1988
  • This paper assesses the models in the SCDAP code using the results of the FLHT-2 test. Calculations show that the SCDAP correctly predicts Ire temperatures, oxidation front movement, overall hydrogen generation and peak generation rate, internal fuel rod pressure, and cladding rupture due to ballooning. A comparison of the calculated results with measured data shows that two phase level is underpredicted, and that radiation heat transfer and auto-catalytic reaction temperature of zircaloy are overpredicted. These models are recommended to be modified. The analysis also shows that the simulation of the gap in a fuel rod improves the code prediction on core damage progression.

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Effect of Brazing Process Variables on joining Characteristics of Ni-based Superalloy (니켈기 초합금의 접합특성에 미치는 브레이징 공정변수의 영향)

  • Kim Gyeong-Ho;Kim Gwang-Ho;Lee Min-Gu;Lee Ho-Jin;Kim Heung-Hoi;Kim Suk-Hwan
    • Proceedings of the KWS Conference
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    • 2006.05a
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    • pp.266-268
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    • 2006
  • The effects of the brazing temperature and homogenizing time for brazed specimens on the joint of Ni-based superalloys such as Haynes 250, Inconel 617 and Hastelloy-X were investigated. The brazing alloy is nickel base MBF 15. The foil had a thickness of $38{\mu}m$, which was used two sheets of that for the all experiments. The experimental brazing was carried out by a brazing process in a vacuum of approximately $2{\times}10^{-5}$ Torr, an applied pressure of about 0.74MPa and the three kinds of brazing temperatures were 1100, 1150, and $1190^{\circ}C$ for a holding time of 5 to 1440 minutes. Microstructural observations were made on the cross-sectional samples by using an optical microscope(OM), scanning electron microscope(SEM), and electron probe X-ray microanalyzer(EPMA). The tensile tests were performed at room temperature with a cross head speed 1.5 mm/min according to ASTM E8M. The results show that excellent joint tensile strengths of as high as 788MPa were obtained when processed at $1190^{\circ}C$ for 5 minutes.

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Thermal stress analysis of the KSTAR vacuum vessel during bake-outs (KSTAR 진공용기의 베이킹시 열응력해석)

  • 인상렬;윤병주;조승연
    • Journal of the Korean Vacuum Society
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    • v.7 no.4
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    • pp.285-292
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    • 1998
  • The vacuum vessel of the KSTAR tokamak has a so large poloidal cross- section that workers can enter into the inside the vessel. To produce a clean plasma with low impurity concentrations it is planned that the whole vessel including plasma facing components will be baked out at $350^{\circ}C$ and the base pressure of the vessel will be kept in the range of ultra high vacuum. Large thermal stresses are expected during bake-outs to a three-dimensionally complex structure of the vessel, consequent ununiformity of the temperature distribution and support systems to resist forces acting on the vessel. In this report variations of the thermal stress according to temperature gradients on the vessel and constraint conditions of supporting structures are studied and some possible counterplans are discussed.

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Rounded Entry Orifice Characteristics for Pressurization Control (가압제어용 둥근 유입형 오리피스 특성)

  • Chung, Yong-Gahp;Kwon, Oh-Sung;Jang, Je-Sung;Shin, Dong-Sung;Han, Sang-Yeop
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.401-404
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    • 2008
  • Pressurization system in a liquid-propellant launcher supplies the controlled gas into the ullage volume of propellant tanks to feed propellants to combustion chamber by pressurizing propellants stored in propellant tanks. The ullage part of propellant tank should be constantly pressurized to supply the propellants stored in propellant tanks to turbo-pump or combustion chamber by pressurant pressurization system. Pressurant used to pressurize propellants is generally stored in a series of tanks at cryogenic temperature and high preassure inside an oxidizer tank. The reason is to store the quantity of pressurant as much as possible and to make pressurant tanks as small as (i.e. as light as) possible. However for test convenience pressurant tank is located at STP (standard temperature and pressure) environment in this study. Orifices are widely adapted to several pressurization systems in liquid rocket propulsion systems. Discharge coefficients of orifices are essentially needed for the optimized design of pressurization system in liquid rocket propulsion system. For this study gaseous nitrogen was served as pressurant and rounded entry orifices were employed. The forty-two (42) rounded entry orifices (the radii of curvatures are 0.5 and 1.0) have been tested experimentally in the supersonic flow region. The discharge coefficients of rounded entry orifices with inside diameters ranging from about 1.4 to 5.0mm was measured with 0.95 ${\sim}$ 0.99.

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The Evaluation of the Creep Properties of ZIRLO Cladding Using the Ring Specimen (링 시험편을 이용한 ZIRLO 피복관의 크리프 특성 평가)

  • Bae Bong-Kook;Koo Jae-Mean;Seok Chang-Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.7 s.238
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    • pp.964-969
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    • 2005
  • In this study, we suggested the ring creep test using the ring specimen of Arsene for estimating the burst creep properties of the cladding in stead of burst creep test. For this objective, we used the load-displacement conversion relationship of ring specimen called LCRR which had been determined on our previous study at high temperature by performing the ring tensile test and the numerical analysis. Then we carried out both the ring creep test and the burst creep test between $350^{\circ}C$ and $600^{\circ}C$ which were higher than the in-service temperature of the cladding in a reactor. The creep properties from the ring creep test with applying LCRR were compared with those from the burst creep test of closed-end specimens. From the results, it could be seen an very strong relationship between them, especially in Larson-Miller parameter. So, it is expected that we can easily predict the creep properties of not only claddings but also various small pressure pipes using the ring creep test.

Preparation of Alumino-silicate Membrane and Its Application to a Gas Separation

  • 김태환
    • Proceedings of the Membrane Society of Korea Conference
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    • 2002.04a
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    • pp.23-46
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    • 2002
  • The cryogenic, pressure swing adsorption and membrane methods have been used to separate air into nitrogen and oxygen. The air separation membrane is made of the polymers, of which manufacturing process is complicate and it causes a little high production cost. Polymer membrane has temperature limit in usage and low durability even at moderate temperature. Therefore, inorganic membranes have been studied for years. As formation of unit alumino-silicate membrane, unit cells of membrane were made with a few coating methods. In this study the dipping of substrate into sols, application of vacuum to the opposite side of substrate with coating and rotating of the substrate in the sols were found as good coating memthods to make a uniform coating and to control the thickness of membrane. The membrane coats were examined by SEM and XRD. The sample ESZl-1 was compared with those of samples that prepared by another method. The present developed coating methods could be applied to the various types of zeolite membrane formation, that is A- X-, Y- ZSM- and MCM-types of membranes. Also these membrane forming methods could be applied to formation of catalyst absorbed zeolite membrane, of which zeolite absorb the catalytic metals. The product obtained from these coating methods could be applied to the industrial gas and liquid phase catalytic reaction and separation processes.

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A Syudy on the Diffusion Joining of 7000 Al Alloy (7000계 Al 합금의 확산접합에 관한 연구)

  • Jin, Y.C.;Hong, E.S.;Kim, Y.S.;Lee, M.S.;Yoo, C.Y.
    • Journal of the Korean Society for Heat Treatment
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    • v.6 no.1
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    • pp.9-16
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    • 1993
  • To investigate the properties of diffusion bonding of 7050 Al alloy, the diffusion bonding joints have been produced in self-made diffusion bonding hot-press which admits a defined application of the bonding pressure during the heating phase and also rapid cooling after the bonding process with various bonding condition. The strength of the bond increases with increasing the bonding time and temperature. Shear test at toom temperature showed that high strength up to 70% that of parent metal (320 MPa), 220 MPa for the specimen bonded 14 hr at $560^{\circ}C$, with 3 MPa. In this case, however, there is large deformation more than 20% reduction in thickness. The results were correlated with joint characteristics found by optical microstructure and by fractography by SEM. When the strengths of the bonds are more than 50% that of parent metal, a great deal of dimples stretched along the direction of shear stress are observed over the fractured surface of the bond. On the microstructure of the bond line, initial mophology of the bond line disapeared for the grain boundary migration with increasing the bonding time.

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Electrical Resistivity Monitoring of Gas Hydrate Formation (가스하이드레이트 형성 과정의 비저항 모니터링)

  • Lee, J.Y.;Lee, J.H.;Lee, D.S.;Lee, W.S.;Kim, S.J.;Huh, D.G.;Kim, H.T.
    • 한국신재생에너지학회:학술대회논문집
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    • 2008.10a
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    • pp.186-187
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    • 2008
  • Electrical resistivity in hydrate-bearing sediments is sensitive to porosity, gas hydrate saturation, gas content, pore fluid composition, and temperature, so electrical measurements such as well logs and electromagnetic surveys have been used to explore gas hydrate-bearing formation. The high pressure tomography cell is designed considering the effect of electrode configuration and electrical shielding on tomography measurements and the safety. The evolution of electrical conductivity during $CO_2$ hydrate formation and dissociation reflects the combined effects of concurrent changes that include ionization of dissolved $CO_2$, temperature-dependent ionic mobility, changes in the degree of saturation, ion exclusion, surface conduction, and porosity changes. Measurements during hydrate formation and dissociation require careful analysis to properly interpret signatures, in particular when out-of plane conductivity anomalies prevail.

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Weathering of coal and kerogen : implications on the geochmical carbon and oxygen cycle and the environmental geochemical reactions (탄질 유기물과 케로젠의 풍화 : 탄소와 산소의 지화학적 순환 및 환경화학적 반응에 미치는 영향)

  • 장수범
    • Economic and Environmental Geology
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    • v.32 no.1
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    • pp.101-111
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    • 1999
  • Sedimentary organic matter, exposed to continental surficial environment, reacts with oxygen supplied from the atmosphee and forms carbon-containing oxidation products. Knowledge of the rate and mechanisms of sedimentary organic matter weathering is important because it is one of the major controls on atmospheric oxygen level through geologic time. Under the abiological conditions, the oxidation rate of coal organic matter by molecular oxygen is enhanced by the increase of oxygen concentration and temperature. At ambient temperature and pressure, aqueous coal oxidation results in the formation of dissolved $CO_2$ dissolved organic carbon and solid oxidation products which are all quantitatively significant reaction products. The effects of pH, ultraviolet light, and microbial activity on the weathering of sedimentary organic matter are poorly contrained. Based on the results of geochmical and environmental studies, it is believed that the photochemical reaction should play an important role in the decomposition and oxidation of sedimentary organic matter removed from the weathering profile. At higher pH conditions, the production rate of DOC can be accelerated due to base catalysis. These high molecular weight oranic matter can react with man-made pollutants such as heavy metal ions via adsorption/desorption or ion exchange reactions. The effect of microbial activity on the oxidative weathering of sedimentary organic matter is poorly understood and remains to be studied.

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Fabrication of SiCN microstructures for super-high temperature MEMS using PDMS mold and its characteristics (PDMS 몰드를 이용한 초고온 MEMS용 SiCN 미세구조물 제작과 그 특성)

  • Chung, Gwiy-Sang;Woo, Hyung-Soon
    • Journal of Sensor Science and Technology
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    • v.15 no.1
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    • pp.53-57
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    • 2006
  • This paper describes a novel processing technique for fabrication of polymer-derived SiCN (silicone carbonitride) microstructures for super-temperature MEMS applications. PDMS (polydimethylsiloxane) mold is fabricated on SU-8 photoresist using standard UV photolithographic process. Liquid precursor is injected into the PDMS mold. Finally, solid polymer structure is cross-linked using HIP (hot isostatic pressure) at $400^{\circ}C$, 205 bar. Optimum pyrolysis and annealing conditions are determined to form a ceramic microstructure capable of withstanding over $1400^{\circ}C$. The fabricated SiCN ceramic microstructure has excellent characteristics, such as shear strength (15.2 N), insulation resistance ($2.163{\times}10^{14}{\Omega}$) and BDV (min. 1.2 kV) under optimum process condition. These fabricated SiCN ceramic microstructures have greater electric and physical characteristics than bulk Si wafer. The fabricated SiCN microstructures would be applied for supertemperature MEMS applications such as heat exchanger and combustion chamber.