• Title/Summary/Keyword: rotational inertia

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Mode Localization in Multispan Beams with Massive and Stiff Couplers on Supports (지점 위에 질량과 강성이 큰 연결기를 갖는 다경간 보의 모드편재)

  • Dong-Ok Kim;Sun-Kyu Park;In-Won Lee
    • Journal of KSNVE
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    • v.8 no.6
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    • pp.1166-1171
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    • 1998
  • The influences of the coupler consisting of stiffness and mass between neighboring two spans on mode localization are studied theoretically, and the results are confirmed by numerical examples. The mass of the coupler makes a structure sensitive to mode localization especially in higher modes while the stiffness does in all modes. A new type of delocalization phenomenon is observed for the first time in some modes for which mode localization does not occur or is very weak although structural disturbances are severe. A spring-mass system consisting of two substructures and a coupler connecting them is considered in the part of analytical study. As example structures for numerical analysis. simply supported continuous two-span beams with a coupler having a rotational stiffness and a mass moment of inertia on the mid support are considered.

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Performance analysis of the optical displacement sensor for accurate in-plane motion measurement (정확한 평면운동 측정을 위한 광 변위센서의 성능분석)

  • Kang, Hoon;Lee, Hunseok;Oh, Jin-Seok
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.3
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    • pp.639-646
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    • 2016
  • In this study, the contactless measurement method with a optical displacement sensor(ODS, ADNS 9500) was proposed to overcome flaws in a rotary encoder based measurement under particular circumstances, such as a slippage and a case of little rotational inertia. The performance tests of the optical displacement sensor using data acquisition board and National Instruments's LabVIEW program were performed to accomplish accurate displacement measurements and the performance characteristics according to measurement direction, speed, acceleration, height and surface types were discovered through the repetitive tests. The experimental results indicate that, in order to get an accurate in-plane motion, the height(distance between the ODS and the target surface) has to be maintained at the range of 2.4 mm to 3.2 mm and the sensitivity(resolution) should be modified and applied to the formulae for displacement calculation, considering its measurement direction, speed and surface type.

CO OBSERVATIONS AND STABILITY ANALYSIS OF B133 AND B134

  • Hong, S.S.;Kim, H.G.;Park, S.H.;Park, Y.S.;Imaoka, K.
    • Journal of The Korean Astronomical Society
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    • v.24 no.1
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    • pp.71-94
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    • 1991
  • With the 14 m radio telescope at DRAO and the 4 m at Nagoya University, we have made detailed maps of $^{12}CO$ and $^{13}CO$ emissions from two Barnard objects B133 and B134 in the $J=1{\rightarrow}O$ rotational transition lines. Usual LTE analyses of the CO observations led us to determine the distribution of column densities over an entire area encompassing both globules. Total gas masses estimated from the column density map are $90\;M_{\odot}$ and $20\;M_{\odot}$ for B133 and B134, respectively. The radial velocity of B133 is red shifted with respect to B134 by $0.8\;km\;s^{-1}$, which is too lagre to bind the two clouds as a binary system. We have shown that the usual stability analysis based on the simplified version of virial theorem with the second time-derivative of the moment of inertia term $\ddot{I}$ being ignored could mislead us in determining whether a given cloud eventually collapses or not. The lull version of the scalar virial theorem with the $\ddot{I}$ term is shown to be useful in following up the time-dependent variations of the cloud size R and its streaming velocity $\dot{R}$ as functions of time. Results of our stability analysis suggest that B133 will eventually collapse in $(2{\sim}4){\times}10^6$ years.

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Free Vibrations of Linearly Tapered I-Beams (선형(線形) 변단면(變斷面) I-형(型) 부재(部材)의 자유진동(自由振動))

  • Lee, Yong Woo;Min, Kyung Ju
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.5
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    • pp.1023-1031
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    • 1994
  • The closed forms of consistent mass matrix with rotational inertia matrix are developed for free vibration analysis in space sutructures containing linearly tapered members with cross section of thin-walled I-sections. The exact displacement functions are used for formulating mass matrices. The very small slopes of the tapered member are used in usual practice, such that the series expansion forms of these are also developed to avoid numerical failure in vibration analysis. Significant improvements of accuracy and efficiency of free vibation analysis are achieved by using the mass matrices developed in this study. Frequencies of free vibation of tapered members are compared with solutions based upon stepped representation of beam element in the ANSYS. The mass matrices presented in this study can be used for the free vibration analysis of tapered and prismatic members.

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Flexural natural vibration characteristics of composite beam considering shear deformation and interface slip

  • Zhou, Wangbao;Jiang, Lizhong;Huang, Zhi;Li, Shujin
    • Steel and Composite Structures
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    • v.20 no.5
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    • pp.1023-1042
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    • 2016
  • Based on Hamilton's principle, the flexural vibration differential equations and boundary conditions of the steel-concrete composite beam (SCCB) with comprehensive consideration of the influences of the shear deformation, interface slip and longitudinal inertia of motion were derived. The analytical natural frequencies of flexural vibration were compared with available results previously observed by the experiments, the results calculated by the FE model and the other similar beam theories available in the open literatures. The comparison results showed that, the calculation results of the analytical and Timoshenko models had a good agreement with the results of the experimental test and FE model. Finally, the influences of shear deformation and interface slip on the flexural natural frequencies of the SCCB were discussed. The shear deformation effect increases with the increase of the mode orders of flexural natural vibration, and the flexural natural frequencies of the higher mode orders ignoring the influence of shear deformations effect would be overestimated. The interface slip effect decrease with the increase of the mode orders of flexural natural vibration, and the influence of the interface slip effect on flexural natural frequencies of the low mode orders is significant. The influence of the degree of shear connection on shear deformation effect is insignificant, and the low order modes of flexural natural vibration are mainly composed of the rotational displacement of cross sections.

An Application of Radio-Controlled Model Testing Techniques to Validation of Air-Vehicle Design Configuration (비행체 설계 형상 타당성 확인을 위한 무선조종 모형시험 기법 적용)

  • Chung, In-Jae;Kim, Myung-Seong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.1
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    • pp.66-72
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    • 2007
  • an approach to air-vehicle design, an application of the radio-controlled model flight test techniques has been presented. The approach presented in this study is to validate the air-vehicle design configuration by analyzing the flight test results of scale model with dynamic similarities, and then to apply the analyzed results to the aerodynamic design process in early stage of the air-vehicle development. To develop practically applicable similarity laws for the subscale flying model design, the air-vehicle motions are decoupled into rotational motions for stability & control similarities and translational motions for flight performance similarities. Also, detail techniques for radio-controlled model flight test have been developed. Based on the results obtained from the radio-controlled flight test, the present approach for air-vehicle design has shown to be useful to validate the air-vehicle design configuration.

Isotope Effects on Vapor Pressure (증기압에 미치는 동위원소 효과)

  • Youngie Oh;Mu Shik Jhon
    • Journal of the Korean Chemical Society
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    • v.21 no.2
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    • pp.75-82
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    • 1977
  • The isotope effect of pure liquid on vapor pressure is examined, and the vapor pressure ratios of two different isotopes are calculated. Based on the Significant Structure Theory of Liquids, the effect of molecular weight and the effect of moments of inertia are dominant in ordinary/trans-$d_2$ ethylene isotopes; the effect of hindered rotational zero-point energy is dominant in trans-$d_2$/cis-$d_2$ ethylene isotopes; and the effect of intermolecular potential difference is found in $CH_3OH/CH_3OD$ isotopes. In the isotopes of $CH_4/CD_4,\;SiH_4/SiD_4\;and\;GeH_4/GeD_4$, the weight effect decrease in the order of $CH_4/CD_4 >SiH_4/SiD_4 >GeH_4/GeD_4$.

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Theoretical Investigation of 2DOF Vibrating System and Its Application to Dynamic Vibration Absorber (2자유도 진동계에 관한 이론적 고찰 및 진동흡진기로의 응용)

  • Jang, Seon-Jun;Brennan, M.J.;Rustigh, E.;Jung, Hyung-Jo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.4
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    • pp.371-377
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    • 2009
  • In this paper, the dynamic characteristic of vibrating system which has translational and rotational degrees of freedom is studied. The moment of inertia of the system is modeled here as the inerter and the equivalent model to the system is proposed using dynamic stiffness method. It is shown that the size of inerter plays a major role to determine the dynamic characteristic of the system. This two degree of freedom system(DOF) is applied as a dynamic vibration absorber(DVA) to the elimination of single peak of main body. The solution for the undamped DVA is presented in analytical form while the damped DVA is designed using fixed point theory. The numerical examples are presented for verifying the methods.

Free Vibration Analysis of a Two-Layered Structure - Formulation by the Transfer Infiuence Coefficient Method - (2층 구조물의 자유진동해석 - 전달영향계수법에 의한 정식화 -)

  • Mun, Deok-Hong;Yeo, Dong-Jun;Kim, Won-Cheol
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.27 no.4
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    • pp.303-312
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    • 1991
  • This paper describes the general formulation for the in-plane flexural free vibration analysis of two layered structure by the transfer influence coefficient method. The structure is regared as a distributed mass system with lumped mass and inertia moments, massless linear and rotational springs, and joints elements of releases and rolls at which the displacements are discontinuous in each layer. The results of the simple numerical examples on a personal computer demonstrate the validity of the present method, that is, the numerical high accuracy, the high speed, the flexibility for programming of the present algorithm, compared with the transfer matrix method.

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Auto-dump Design of Postharvest Bulk Handling Machinery System for Onions

  • Park, Jongmin;Choi, Wonsik;Kim, Ghiseok;Kim, Jongsoon
    • Journal of Biosystems Engineering
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    • v.43 no.4
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    • pp.379-385
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    • 2018
  • Purpose: Postharvest handling of onions (harvesting, cleaning, grading, cooling, storing, and transport) should be performed continually to reduce costs and improve quality. The purpose of this study is to a) determine the design parameters and operating conditions of anion auto-dumping that constitutes a key component of the postharvest bulk handling machinery system, and b) to perform a performance test with the auto-dump prototype system. Methods: Kinematic analyses and computer simulations of the auto-dump mechanism were applied to analyze the operating conditions and design parameters. Results: The optimum working condition for the auto-dump was determined from kinetic analyses. In addition, the interaction between the velocity of the hydraulic cylinder and the angular velocity of the auto-dump were analyzed in order to control the bulk handling machinery system. The acting forces and optimum operating conditions of the hydraulic cylinder were determined by analyzing the forces related to the mass of inertia of the auto-dump assembly during rotation. The method of controlling the feeding rate of onions in terms of the uniformity of the stacking pattern and the control of the entire system was better than the two-stage method of controlling the rotational speed of the auto-dump. Based on the performance test with the prototype for the auto-dump, the stacking pattern and rigidity of the system were analyzed. Conclusions: These results would be of great importance in the postharvest bulk handling machinery system for onions.