• Title/Summary/Keyword: pressure differential system

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Closed form solution for displacements of thick cylinders with varying thickness subjected to non-uniform internal pressure

  • Eipakchi, H.R.;Rahimi, G.H.;Esmaeilzadeh Khadem, S.
    • Structural Engineering and Mechanics
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    • v.16 no.6
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    • pp.731-748
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    • 2003
  • In this paper a thick cylindrical shell with varying thickness which is subjected to static non-uniform internal pressure is analyzed. At first, equilibrium equations of the shell have been derived by the energy principle and by considering the first order theory of Mirsky-Herrmann which includes transverse shear deformation. Then the governing equations which are, a system of differential equations with varying coefficients have been solved analytically with the boundary layer technique of the perturbation theory. In spite of complexity of modeling the conditions near the boundaries, the method of this paper is very capable of providing a closed form solution even near the boundaries. Displacement predictions are in a good agreement with the calculated finite elements and other analytical results. The convergence of solution is very fast and the amount of calculations is less than the Frobenius method.

$\pi$-A properties of phospholipid monolayers by Maxwell-displacement-current-measuring technique (변위전류법에 의한 지질 단분자막의 $\pi$-A특성)

  • 이경섭;전동규;권영수;국상훈
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1995.05a
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    • pp.120-123
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    • 1995
  • Maxwell-Displacement-Currnt-Measuring Technique(MDCM) is a simple system for displacement current measuring which consist with two electrodes to the electrometer, With this method, the displacement current flow only when the electric flux density change by the displacement of molecules or charge particles of membrance on the water surface. Thus, It is Possible to detect dynamic behavior of molecules of membrane without any electrical contact with molecule membrane. In this paper, We measure surface pressure, displacement current and dipole moment of phospholipid monolayers on the wafer surface with applied pressure by MDCM and We measured DTA(differential thermal analysis).

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A MODELING PERSPECTIVE OF DELIBERATE SELF-HARM

  • Do, Tae-Sug;Lee, Young-S.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.14 no.4
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    • pp.275-284
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    • 2010
  • Deliberate self-harm (DSH) is the act of deliberately harming your own body, such as cutting or burning yourself, without suicidal intent. It has especially become a problem among adolescents and college-age students in institutional settings such as boarding schools, Greek houses, detention centers and hospitals. We focus on contagion of DSH among adolescents and young adults by creating a deterministic epidemiological model. We study the impact of actual peer pressure, virtual peer pressure (the Internet) and treatment analytically in terms of a basic reproduction number through stability analysis of a system of ordinary differential equations. All parameters are approximated and results are also explored by simulations. The model shows that DSH is present in an endemic state in the population considered, and the control strategies are discussed.

The Ejector Design and Test for 5kW Molten Carbonate Fuel Cell (5kW 용융탄산염 연료전지 이젝터 설계 및 시험)

  • Kim, Beom-Joo;Kim, Do-Hyung;Lee, Jung-Hyun;Jung, Sang-Chun;Lee, Sung-Yoon;Kang, Seung-Won;Lim, Hee-Chun
    • 한국신재생에너지학회:학술대회논문집
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    • 2008.05a
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    • pp.53-56
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    • 2008
  • An ejector is a fluid machinery to be utilized for mixing fluids, maintaining vacuum, and transporting them. The Ejector is applied for a variety of industrial fields such as refrigerators and power plants. It is adopted to recycle anode off gas safely in 5kW Molten Carbonate Fuel Cell system of KEPRI(Korea Electric Power Research Institute). The ejector is placed at mixing point between the anode off gas and the cathode off gas or the fresh air. In this study, the entrainment ratio is measured according to the diametrical ratio of nozzle to throat. In addition, the performance curve of the ejector and the differential pressure in diffuser is observed.

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Development of Micro Displacement Extensometer for Environmental Fatigue Test in a High Temperature and High Pressure Autoclave (고온고압 환경피로실험 오토클래이브 내부용 미소변위 측정장치 개발)

  • Jeong, Ill-Seok;Ha, Gak-Hyun;Kim, Tae-Ryong;Jeon, Hyun-Ik;Kim, Young-Sin
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.368-371
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    • 2008
  • An extensometer system to measure strain and displacement of cylindrical fatigue specimen in a autoclave of high temperature and high pressure environment has been developed by KEPRI. The extensometer reads the displacement caused by fatigue loads at the target length of the specimen installed inside the autoclave. The performance of the extensometer were tested at 15MPa, $315^{\circ}C$ of a operating pressurized water reactor. Two LVDT's of magnet type were connected to the extensometer and used for converting the fatigue displacement to electronic signal. The device is being used for developing environmental fatigue curve of CF8M cast austenitic stainless steel (CASS) in the test condition of low cycle and low strain. This paper introduces the background and results of the development.

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Axisymmetric Finite Element Analysis of Decomposing Polymeric Composites and Structures (열경화성 고분자 복합재 구조물의 축대칭 유한요소해석)

  • Lee, Seon-Pyo
    • 연구논문집
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    • s.24
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    • pp.81-96
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    • 1994
  • To investigate failure mechanisms observed in carbon-phenolic thermal insulators, differential equations which govern the decomposition process in a deformable anisotropic porous solid are derived for three-dimensional axisymmetric constructions. The governing equations not only couple the material deformation with pore pressure, but also couple pressure and temperature, which means that heat convected by the pyrolysis gases is properly accounted for. Then the Bubnov-Galerkin finite element method is applied to these equations to transform them into a semidescrete finite element system. A thermal insulation liner in the cowl region under typical operating conditions is analyzed to find a mechanism for plylift. The results from the structural analysis show across-ply failure in the cowl zone. The mechanism for plylift is hypothesized as a sequential procedure : 1) the across-ply failure which is the precursor to plylift and 2) the local fiber buckling caused by generation of excessive in-plane compressive stress. To prevent plylift, the across-ply stress can be reduced by using appropriate material ply angles in cowl zone design.

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Studies on the Differential Determination of cis-, and trans-Neopynamin and Fenitrothion by High Pressure Liguid Chromatography (고속 액체 크로마토그라피에 의한 cis- 및 trans-Neopynamin과 Fenitrothion의 분리 정량에 관한 연구)

  • 이왕규;정해수
    • YAKHAK HOEJI
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    • v.24 no.2
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    • pp.117-122
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    • 1980
  • A new application of high pressure liquid chromatography for the determination of fenitrothion and cis- and trans-neopynamin in insecticidal preparations was investigated. Optimum conditions for a good separation and determination were determined; solvent system: dichloromethane + n-hexane = 17 + 83; Bow rate: 0.5ml/min; column: u-porasil ($4mm{\times}3Ocm$); absorbance wavelength: 254nm; 0.05 AUFS and sample size: 30 ul. Recovery of fenicrothion, cis- and trans-neopynamin from mixed artificial preparations was 99.6%, 99.7% and 99.8% respectively. Also reproducibility tests showed that the coefficient of variation was 0.89% for fenitrothion, 0.74% cis-neopynamin and 1.1% for trans-neopynamin. There was no interference with insecticidal preparation containing DDVP, allethrin, S-421 and kerosene. HPLC method was rapid, accurate and it gave better reproducibility and higher sensitivity than any other analytical method. It was considered that HPLC could be greatly applied to the analysis of fenitrothion and neopynamin in insecticidal preparations.

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Thermal radiation and some physical combined effects on an asymmetric peristaltically vertical channel of nanofluid flow

  • Amira S. Awaad;Zakaria M. Gharsseldien
    • Advances in nano research
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    • v.16 no.6
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    • pp.579-591
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    • 2024
  • This study explained the effects of radiation, magnetic field, and nanoparticle shape on the peristaltic flow of an Upper-Convected Maxwell nanofluid through a porous medium in an asymmetric channel for a better understanding of cooling and heating mechanisms in the presence of magnetic fields. These phenomena are modeled mathematically as a system of non-linear differential equations, that are solved under long-wavelength approximation and low Reynolds number conditions using the perturbation method. The results for nanofluid and temperature described the behavior of the pumping characteristics during their interaction with (the vertical position, thermal radiation, the shape of the nanoparticle, and the magnetic field) analytically and explained graphically. Also, the combined effects of thermal radiation parameters and some physical parameters on pressure rise, pressure gradient, velocity, and heat distribution are pointed out. Qualitatively, a reverse velocity appears with combined high radiation and Grashof number or combined high radiation and low volume flow rate. At high radiation, the spherical nanoparticle shape has the greatest effect on heat distribution.

Simulation of Reactor and Turbine Poler Transients in CANDU 6 Nuclear Power Plants

  • Park, Jong-Woon-;Yeom, Choong-Sub;Kim, Sung-Bae-
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1994.05a
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    • pp.130-137
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    • 1994
  • As a part of developing engineering simulator for CANDU 6 nuclear power plants, present paper gives the tentative simulation results of reactor and turbine power transients including reactor-follow-turbine operation. One point kinetics equations are used for neutron dynamics, iodine and xenon loads. To calculate time-dependent high and low pressure turbine powers and grid frequency deviation, simple first order differential equations are used. In addition, control logics (reactor regulating system, demand power routine, and unit power regulator) used in the plant's process computers have been referenced.

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CFD ANALYSIS OF HEAVY LIQUID METAL FLOW IN THE CORE OF THE HELIOS LOOP

  • Batta, A.;Cho, Jae-Hyun;Class, A.G.;Hwang, Il-Soon
    • Nuclear Engineering and Technology
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    • v.42 no.6
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    • pp.656-661
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    • 2010
  • Lead-alloys are very attractive nuclear coolants due to their thermo-hydraulic, chemical, and neutronic properties. By utilizing the HELIOS (Heavy Eutectic liquid metal Loop for Integral test of Operability and Safety of PEACER$^2$) facility, a thermal hydraulic benchmarking study has been conducted for the prediction of pressure loss in lead-alloy cooled advanced nuclear energy systems (LACANES). The loop has several complex components that cannot be readily characterized with available pressure loss correlations. Among these components is the core, composed of a vessel, a barrel, heaters separated by complex spacers, and the plenum. Due to the complex shape of the core, its pressure loss is comparable to that of the rest of the loop. Detailed CFD simulations employing different CFD codes are used to determine the pressure loss, and it is found that the spacers contribute to nearly 90 percent of the total pressure loss. In the system codes, spacers are usually accounted for; however, due to the lack of correlations for the exact spacer geometry, the accuracy of models relies strongly on assumptions used for modeling spacers. CFD can be used to determine an appropriate correlation. However, application of CFD also requires careful choice of turbulence models and numerical meshes, which are selected based on extensive experience with liquid metal flow simulations for the KALLA lab. In this paper consistent results of CFX and Star-CD are obtained and compared to measured data. Measured data of the pressure loss of the core are obtained with a differential pressure transducer located between the core inlet and outlet at a flow rate of 13.57kg/s.