• Title/Summary/Keyword: mass formula

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An approximate formula to calculate the fundamental period of a fixed-free mass-spring system with varying mass and stiffness

  • Kim, Juwhan;CoIIins, Kevin R.;Lim, Yun Mook
    • Structural Engineering and Mechanics
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    • v.25 no.6
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    • pp.717-732
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    • 2007
  • A formula to approximate the fundamental period of a fixed-free mass-spring system with varying mass and varying stiffness is formulated. The formula is derived mainly by taking the dominant parts from the general form of the characteristic polynomial, and adjusting the initial approximation by a coefficient derived from the exact solution of a uniform case. The formula is tested for a large number of randomly generated structures, and the results show that the approximated fundamental periods are within the error range of 4% with 90% of confidence. Also, the error is shown to be normally distributed with zero mean, and the width of the distribution (as measured by the standard deviation) tends to decrease as the total number of discretized elements in the system increases. Other possible extensions of the formula are discussed, including an extension to a continuous cantilever structure with distributed mass and stiffness. The suggested formula provides an efficient way to estimate the fundamental period of building structures and other systems that can be modeled as mass-spring systems.

Speed-up Design for Overhead-line Considering Contact Force Fluctuations by a Wave Reflection and a Doppler Effect (파동반사와 도플러 효과를 고려한 전차선의 속도향상 설계)

  • Cho Yong Hyeon;Lee Ki Won;Kwon Sam Young;Kim Do Won
    • Proceedings of the KSR Conference
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    • 2004.10a
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    • pp.1353-1359
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    • 2004
  • There are many massive components added on the railway overhead-line. These components cause larger fluctuations of contact forces, which are due to wave reflections and Doppler effects when a high-speed train passes those. In this paper, mathematical formula are derived for the relation between the added mass and contact force fluctuations. Using the derived formula, we calculate a added mass on the overhead-line which cause amplification factor to become 2.5. German design practice requires that amplification factor due to the wave reflection should be less than 2.5 to obtain good current collection performance. To show the validity of the formula, simulation results are compared with the calculation results. Simulation results showed that contact force fluctuations grow rapidly when an added mass is larger than the calculation result. Therefore, the simple form of formula can be used for estimating maximum added mass not to cause large fluctuations of contact forces in early design phase.

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Survey of Inositol in Infant Formula

  • Patel, A.;Ditiatkovski, M.;Kennedy, L.;Oglobline, A.;Choi, N.;Richardson, G.
    • Mass Spectrometry Letters
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    • v.7 no.1
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    • pp.12-15
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    • 2016
  • Results of free and bound myo-inositol in infant formula (IF) are presented. Inositol was analyzed by HILIC ultra-performance liquid chromatography coupled with mass spectrometer. The levels of free myo-inositol in 27 Australian and 4 EU originated IF samples were 300-600 mg/kg of powder or 1.6-3.1 mg/100 kJ. The amount of bound inositol in lipid fraction of IF was, on average, 10% of free myo-inositol.

Natural Frequency of 2-dimensional Heaving Circular Cylinder (상하동요하는 2차원 원주의 고유진동수)

  • Lee, Seung-Joon
    • Journal of the Society of Naval Architects of Korea
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    • v.45 no.4
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    • pp.389-395
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    • 2008
  • It is very well known that the natural frequency of an oscillating body on the free surface is determinable only after the added mass is given. However, it is hard to find analytical investigations in which actually the natural frequency is obtained. Difficulties arise from the fact that in order to determine the natural frequency we need to compute the added mass at least for a range of frequencies, and to solve an equation where the frequency is a variable. In this study, first, a formula is obtained for the added mass, and then an equation for finding the natural frequency is defined and solved by Newton's iteration. It is confirmed that the formula shows a good agreement with the results given by Ursell(1949), and the value of natural frequency is reduced by 21.5% compared to the pre-natural frequency, which is obtained without considering the effect of added mass.

Simplified formulas of heave added mass coefficients at high frequency for various two-dimensional bodies in a finite water depth

  • Koo, Weoncheol;Kim, Jun-Dong
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.1
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    • pp.115-127
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    • 2015
  • The aim of this study is to develop a simplified formula for added mass coefficients of a two-dimensional floating body moving vertically in a finite water depth. Floating bodies with various sectional areas may represent simplified structure sections transformed by Lewis form, and can be used for floating body motion analysis using strip theory or another relevant method. Since the added mass of a floating body varies with wave frequency and water depth, a correction factor is developed to take these effects into account. Using a developed two-dimensional numerical wave tank technique, the reference added masses are calculated for various water depths at high frequency, and used them as basis values to formulate the correction factors. To verify the effectiveness of the developed formulas, the predicted heave added mass coefficients for various wetted body sections and wave frequencies are compared with numerical results from the Numerical Wave Tank (NWT) technique.

A Study on the Comparative Method of Prescription Using Herb Weight Ratio (방제의 본초 중량비를 활용한 방제 비교 방안에 관한 연구)

  • Park, Daesik;Lee, Bookyun;Lee, Byung Wook
    • Herbal Formula Science
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    • v.21 no.2
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    • pp.121-132
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    • 2013
  • Objectives : The objectives of this study is to establish data-base to find out similar herbal formulas with a particular herbal formula by comparing composition ratio of configuring herbs. And this thesis is to analyze differences of prescriptions and find out similar prescriptions by utilizing galenical mass ratio, which is directly related to effectiveness of galenical. Methods : This study was proceeded by using Access 2007 with Window 7(MS) and 2,787 prescriptions of which herbal configuration could be indicated by weight unit were analysed from Donguibogam. We standardize all units of the prescription and input the mass ratio data when entered galenical data. Results : We could confirm a degree of similarity between compared prescriptions and a particular prescription according to the sum of differences of herb weight ratio and similarity ratio. Conclusions : A most similar herbal formula could be searched through comparing multi prescriptions by multi prescriptions of herbal configuration from established herbal formula data-base where herb weight ratio of prescriptions is to be input.

Re-derivation of Added Mass Coefficient of Circular Cylinder near Bottom Boundary (바닥경계 가까이 있는 원형실린더의 부가질량계수의 재유도)

  • 편종근;박창근
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.6 no.3
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    • pp.275-280
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    • 1994
  • The analytic solution of the forces acting on a horizontal circular cylinder affected by the bottom boundary is re-derived using the complex potential. The reason of the re-derivation of the analytic solution is such that it is found that the analytic solution of Yamamoto et al. (1974) does not simulate the behavior of the added mass coefficient accurately. The re-derived formula of the added mass coefficient CD is different from that of Yamamoto et al (1974), while the re-derived formula of Cm simulates the tendency of the behavior of the added mass coefficient success-fully.

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