• Title/Summary/Keyword: static parameters

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An Analysis of Load Characteristics of Air-Lubricated Herringbone Groove Journal Bearing By Finite Element Method (공기윤활 빗살무늬 저널베어링의 부하특성에 대한 유한요소해석)

  • 박신욱;임윤철
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.11a
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    • pp.353-362
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    • 2000
  • Herringbone groove journal bearing (HGJB) is developed to improve the static and dynamic performances of hydrodynamic journal bearing. In this study, static and dynamic compressible isothermal lubrication problems are analyzed by the finite element method together with the Newton-Raphson iterative procedure. This analysis is introduced for prediction of the static and dynamic characteristics of air lubricated HGJB for various bearing configurations. The bearing load characteristics and dynamic characteristics are dependent on geometric parameters such as asymmetric ratio, groove depth ratio, groove width ratio and groove angle.

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Evaluation of static response in stress-ribbon concrete pedestrian bridges

  • Stavridis, Leonidas T.
    • Structural Engineering and Mechanics
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    • v.34 no.2
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    • pp.213-229
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    • 2010
  • An analytical method is proposed for the evaluation of the static response of a prestresse-dribbon concrete pedestrian bridge, which may also be applied for the roofing of large areas. On the basis of an established analogy with a suspension bridge system, a procedure is presented for the prestresse-dribbon direct analysis, leading to the introduction of two dimensionless parameters as governing factors of the design, namely the thinness and the prestressing steel ratio. The exposed procedure, applied by a simple computer program, allows a quick evaluation of the response and permits the investigation of the influence of the aforementioned parameters on it, by means of comprehensive diagrams. The presented diagrams may be directly used for the preliminary design of a pedestrian bridge of this type, for the whole practical range of span lengths. A design example is also included, showing the applicability of the proposed procedure.

Proposal for Increase of Thermal Margin in COLSS

  • Lee, Byung I.;Kim, Du I.;Kim, Jong J.;Kil S. Um;Lee, Chong C.
    • Proceedings of the Korean Nuclear Society Conference
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    • 1997.05a
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    • pp.508-513
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    • 1997
  • One of the moot important constants to be Installed In COLSS, a monitoring system in CE typed reactors, is ROPM which would limit the operating space. This static ROPM was calculated from digital transient analysis assuming that every design basis transient was initiated from the most severe initial condition combination (LCO). Once It could be assured that core condition would not be located at none other than LCO, this static ROPM could be replaced with dynamic ROPM calculated at that condition and the dynamic ROPM would be definitely less than the static ROPM. In order to do, It must be required to calculate the transient discrete sensitivity parameters and parameters change distribution. The purpose of this report is just to propose the enlargement method for thermal margin.

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Glass Dissolution Rates From MCC-1 and Flow-Through Tests

  • Jeong, Seung-Young
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2004.06a
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    • pp.257-258
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    • 2004
  • The dose from radionuclides released from high-level radioactive waste (HLW) glasses as they corrode must be taken into account when assessing the performance of a disposal system. In the performance assessment (PA) calculations conducted for the proposed Yucca Mountain, Nevada, disposal system, the release of radionuclides is conservatively assumed to occur at the same rate the glass matrix dissolves. A simple model was developed to calculate the glass dissolution rate of HLW glasses in these PA calculations [1]. For the PA calculations that were conducted for Site Recommendation, it was necessary to identify ranges of parameter values that bounded the dissolution rates of the wide range of HLW glass compositions that will be disposed. The values and ranges of the model parameters for the pH and temperature dependencies were extracted from the results of SPFT, static leach tests, and Soxhlet tests available in the literature. Static leach tests were conducted with a range of glass compositions to measure values for the glass composition parameter. The glass dissolution rate depends on temperature, pH, and the compositions of the glass and solution, The dissolution rate is calculated using Eq. 1: $rate{\;}={\;}k_{o}10^{(ph){\eta})}{\cdot}e^{(-Ea/RT)}{\cdot}(1-Q/K){\;}+{\;}k_{long}$ where $k_{0},\;{\eta}$ and Eaare the parameters for glass composition, pH, $\eta$ and temperature dependence, respectively, and R is the gas constant. The term (1-Q/K) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_{0},\;{\eta}\;and\;E_{a}$ are the parameters for glass composition, pH, and temperature dependence, respectively, and R is the gas constant. The term (1-Q/C) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_0$, and Ea are determined under test conditions where the value of Q is maintained near zero, so that the value of the affinity term remains near 1. The dissolution rate under conditions in which the value of the affinity term is near 1 is referred to as the forward rate. This is the highest dissolution rate that can occur at a particular pH and temperature. The value of the parameter K is determined from experiments in which the value of the ion activity product approaches the value of K. This results in a decrease in the value of the affinity term and the dissolution rate. The highly dilute solutions required to measure the forward rate and extract values for $k_0$, $\eta$, and Ea can be maintained by conducting dynamic tests in which the test solution is removed from the reaction cell and replaced with fresh solution. In the single-pass flow-through (PFT) test method, this is done by continuously pumping the test solution through the reaction cell. Alternatively, static tests can be conducted with sufficient solution volume that the solution concentrations of dissolved glass components do not increase significantly during the test. Both the SPFT and static tests can ve conducted for a wide range of pH values and temperatures. Both static and SPFt tests have short-comings. the SPFT test requires analysis of several solutions (typically 6-10) at each of several flow rates to determine the glass dissolution rate at each pH and temperature. As will be shown, the rate measured in an SPFt test depends on the solution flow rate. The solutions in static tests will eventually become concentrated enough to affect the dissolution rate. In both the SPFt and static test methods. a compromise is required between the need to minimize the effects of dissolved components on the dissolution rate and the need to attain solution concentrations that are high enough to analyze. In the paper, we compare the results of static leach tests and SPFT tests conducted with simple 5-component glass to confirm the equivalence of SPFT tests and static tests conducted with pH buffer solutions. Tests were conducted over the range pH values that are most relevant for waste glass disssolution in a disposal system. The glass and temperature used in the tests were selected to allow direct comparison with SPFT tests conducted previously. The ability to measure parameter values with more than one test method and an understanding of how the rate measured in each test is affected by various test parameters provides added confidence to the measured values. The dissolution rate of a simple 5-component glass was measured at pH values of 6.2, 8.3, and 9.6 and $70^{\circ}C$ using static tests and single-pass flow-through (SPFT) tests. Similar rates were measured with the two methods. However, the measured rates are about 10X higher than the rates measured previously for a glass having the same composition using an SPFT test method. Differences are attributed to effects of the solution flow rate on the glass dissolution reate and how the specific surface area of crushed glass is estimated. This comparison indicates the need to standardize the SPFT test procedure.

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Numerical Investigation of the Flow and Mixing Characteristics with the Static Mixer in a Catalytic Combustor for the MCFC Power Plant System (MCFC 발전시스템 적용 촉매연소기의 혼합 특성 향상을 위한 Static Mixer의 유동에 관한 수치적 연구)

  • Kim, Chong-Min;Park, Nam-Seob;Kim, Man-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.3
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    • pp.149-155
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    • 2009
  • In this work a numerical study to find the characteristics of the internal flow and mixing process has been conducted in a static mixer used in the system of catalytic combustor of the fuel cell power plant. After introducing the model description and final governing equations the present numerical approach is applied to the analysis of static mixer, which may have one or more helical elements inside the circular tube by changing such various parameters as incoming mass flow rates and the number of helical elements. The results show that although the static mixer is efficient in mixing fuel and air, more optimization processes are required to achieve the appropriate mixing characteristics in front of the honeycomb type catalytic combustor used in the MCFC power plant

A Study and Investigation on the Influence of Static and Dynamic Loading on the Properties of Handmade Persian Carpet (I) - The Effect of Static Loading -

  • Mirjalili S. A.;Sharzehee M.
    • Fibers and Polymers
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    • v.6 no.2
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    • pp.139-145
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    • 2005
  • The paper reports the physical and mechanical properties of hand-woven carpets, which have been put under static force. Two groups of wool fibres, from two parts of Iran, were prepared to spin pile yams for the carpets. Each group of the fibres included both conventional and tanned wool. Then two yam counts, $N_m$ = 4/2 and 6/2, were spun for two different knot densities. After weaving the carpets, they were put under static force and their thickness variations were measured and plotted against time, in logarithm scale. The resiliency of the carpets piles after eliminating the static force, were measured and plotted against time, in logarithm scale, too. The results were compared to each other and analysed with respect to parameters such as the type and quality of the wool fibres as well as knot density of the carpets.

A Study on the Analysis and Measurement for the Elasticity of the Catenary System (전차선로 탄성도 해석 및 측정에 관한 연구)

  • 조용현;최강윤;조기조;권삼영
    • Proceedings of the KSR Conference
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    • 2002.10b
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    • pp.1100-1105
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    • 2002
  • The elasticity of the contact wire is one of important static parameters for the catenary system. This paper presents how to analyse the elasticity of the catenary system using both simple string model method and finite element method with their formula. Analysis results obtained by these two methods for KTX catenary system are compared. A measurement of the elasticity for the KTX catenary under construction which is located near Kumkang bridge is made for the comparison with the analysis results. Both a dynamic and a static methods are tried for the measurement. Because of wave propagation, the dynamic method with 5 km/h running presented an asymmetric variational pattern of the elasticity while the static method presented a symmetric pattern of the elasticity in the span. Measured elasticity using the static method is found to be a little higher than the analysis results. But, the static method can presented us a variational pattern of the elasticity in the span similar to the analysed results. Therefore, the static method can be used for evaluating the elasticity of the catenary system

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An Evaluation of the Tolerance of the Static Characteristics for Light Weight Torpedoes (경어뢰의 정특성 허용오차 산정)

  • 나영인
    • Journal of the Korea Institute of Military Science and Technology
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    • v.5 no.2
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    • pp.149-158
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    • 2002
  • Static Characteristics of the system, such as weight, center of gravity etc., are inspected and regulated through the whole design process of a light weight torpedo system, and the nominal condition of the characteristics is prescribed for standardization of manufacturing and fabrication. It is possible that a real system or assembled system has different static characteristics from that of the nominal condition. It is required to evaluate the tolerance of the static characteristics within which the performance of the system should not be contaminated by the static characteristics. In this paper, an evaluation method of the tolerance is described for light weight torpedo systems. The method is to check on the performance and related critical parameters of light weight torpedoes. The checking items are composed of general conditions of underwater mobile systems such as stability and dynamic sensitivity and specified performance requirements for light weight torpedoes.

Eringen's nonlocal theory for non-linear bending analysis of BGF Timoshenko nanobeams

  • Azandariani, Mojtaba Gorji;Gholami, Mohammad;Nikzad, Akbar
    • Advances in nano research
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    • v.12 no.1
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    • pp.37-47
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    • 2022
  • In this paper, the non-linear static analysis of Timoshenko nanobeams consisting of bi-directional functionally graded material (BFGM) with immovable ends is investigated. The scratching in the FG nanobeam mid-plane, is the source of nonlinearity of the bending problems. The nonlocal theory is used to investigate the non-linear static deflection of nanobeam. In order to simplify the formulation, the problem formulas is derived according to the physical middle surface. The Hamilton principle is employed to determine governing partial differential equations as well as boundary conditions. Moreover, the differential quadrature method (DQM) and direct iterative method are applied to solve governing equations. Present results for non-linear static deflection were compared with previously published results in order to validate the present formulation. The impacts of the nonlocal factors, beam length and material property gradient on the non-linear static deflection of BFG nanobeams are investigated. It is observed that these parameters are vital in the value of the non-linear static deflection of the BFG nanobeam.

The study on the Characteristics of Ultimate Bearing Capacity and Major Design Parameters for Single Stone Column (단일 쇄석다짐말뚝의 지지력 특성과 주요 설계 파라미터에 관한 고찰)

  • Chun, Byung-Sik;Kim, Won-Cheul;Jo, Yang-Woon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2004.03b
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    • pp.552-560
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    • 2004
  • Stone column is a soil improvement method and can be applicable for loose sand or weak cohesive soil. Since the lack of sand in Korea, stone column seems one of the most adaptable approach for poor ground as a soil improvement method. However, this method was not studied for practical application. In this paper, the most effective design parameters for the being capacity of stone column were studied. The parametric study of major design factors for single stone column was carried out under the bulging and general shear failure condition, respectively. Especially, a test result of single stone column by static load was compared with the bearing capacity values of suggested formulas. The analysis result showed that the ultimate bearing capacity by the formula was much less than the measured value by the static load test. Especially, the result of the parametric study under general shear failure condition showed that the bearing capacity has apparent difference between each suggested formulas with the variation of the major design parameters. Therefore, the result of this study can be a suggestion which is applicable for the field test and the future research.

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