• Title/Summary/Keyword: Multi-body Modeling

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The Forecasting a Maximum Barbell Weight of Snatch Technique in Weightlifting (역도 인상동작 성공 시 최대 바벨무게 예측)

  • Hah, Chong-Ku;Ryu, Ji-Seon
    • Korean Journal of Applied Biomechanics
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    • v.15 no.3
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    • pp.143-152
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    • 2005
  • The purpose of this study was to predict the failure or success of the Snatch-lifting trial as a consequence of the stand-up phase simulated in Kane's equation of motion that was effective for the dynamic analysis of multi-segment. This experiment was a case study in which one male athlete (age: 23yrs, height: 154.4cm, weight: 64.5kg) from K University was selected The system of a simulation included a multi-segment system that had one degree of freedom and one generalized coordinate for the shank segment angle. The reference frame was fixed by the Nonlinear Trans formation (NLT) method in order to set up a fixed Cartesian coordinate system in space. A weightlifter lifted a 90kg-barbell that was 75% of subject's maximum lifting capability (120kg). For this study, six cameras (Qualisys Proreflex MCU240s) and two force-plates (Kistler 9286AAs) were used for collecting data. The motion tracks of 11 land markers were attached on the major joints of the body and barbell. The sampling rates of cameras and force-plates were set up 100Hz and 1000Hz, respectively. Data were processed via the Qualisys Track manager (QTM) software. Landmark positions and force-plate amplitudes were simultaneously integrated by Qualisys system The coordinate data were filtered using a fourth-order Butterworth low pass filtering with an estimated optimum cut-off frequency of 9Hz calculated with Andrew & Yu's formula. The input data of the model were derived from experimental data processed in Matlab6.5 and the solution of a model made in Kane's method was solved in Matematica5.0. The conclusions were as follows; 1. The torque motor of the shank with 246Nm from this experiment could lift a maximum barbell weight (158.98kg) which was about 246 times as much as subject's body weight (64.5kg). 2. The torque motor with 166.5 Nm, simulated by angular displacement of the shank matched to the experimental result, could lift a maximum barbell weight (90kg) which was about 1.4 times as much as subject's body weight (64.5kg). 3. Comparing subject's maximum barbell weight (120kg) with a modeling maximum barbell weight (155.51kg) and with an experimental maximum barbell weight (90kg), the differences between these were about +35.7kg and -30kg. These results strongly suggest that if the maximum barbell weight is decided, coaches will be able to provide further knowledge and information to weightlifters for the performance improvement and then prevent injuries from training of weightlifters. It hopes to apply Kane's method to other sports skill as well as weightlifting to simulate its motion in the future study.

Equivalent Modeling Technique for 1-D Collision Dynamics Using 3-D Finite Element Analysis of Rollingstock (열차의 3차원 유한요소해석을 이용한 1차원충돌 동역학 등가 모델링 기법)

  • Park, Min-Young;Park, Young-Il;Koo, Jeong-Seo
    • Journal of the Korean Society for Railway
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    • v.13 no.2
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    • pp.139-146
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    • 2010
  • In this study, a new equivalent modeling technique of rollingstock for 1-D collision dynamics was proposed using crash analysis of 3-D finite element model in some detail. To obtain good simulation results of 1-D dynamic model, the force-deformation curves of crushable structures should be well modelled with crash analysis of 3-D finite element model. Up to now, the force-deformation curves of the crushable structures have been extracted from crash analyses of sectionally partitioned parts of the carbody, and integrated into 1-D dynamic model. However, the results of the 1-D model were not satisfactory in terms of crash accelerations. To improve this problem, the force-deformation curves of the crushable structures were extracted from collision analysis of a simplified train consist in this study. A comparative study applying the suggested technique shows in good agreements in simulation results between two models for KHST.

Modeling of 3D Monte Carlo Ion Implantation in the Ultra-Low Energy for the Fabrication of Giga-Bit Devices (기가 비트급 소자 제작을 위한 3차원 몬테카를로 극 저 에너지 이온 주입 모델링)

  • Ban, Yong-Chan;Kwon, Oh-Seob;Won, Tae-Young
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.37 no.10
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    • pp.1-10
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    • 2000
  • A rigorous modeling of ultra-low energy implantation is becoming increasingly more important as devices shrink to deep submicron dimensions. In this paper, we have developed an efficient three-dimensional Monte Carlo ion implantation model based on a modified Binary Collision Approximation(BCA). To this purpose, the modified electronic stopping model and the multi-body collision model have been taken into account in this simulator. The dopant and damage profiles show very good agreement with SIMS(Secondary Ion Mass Spectroscopy) data and RBS(Rutherford Backscattering Spectroscopy) data, respectively. Moreover, the ion distribution replica method has been implemented into the model to get a computational efficiency in a 3D simulation, and we have calculated the 3D Monte Carlo simulation into the topographically complex structure.

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Kinematic and Kinetic Analysis of the Soft Golf Swing using Realistic 3D Modeling Based on 3D Motion Tracking

  • Kim, Yong-Yook;Kim, Sung-Hyun;Kim, Nam-Gyun
    • Journal of Biomedical Engineering Research
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    • v.28 no.6
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    • pp.744-749
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    • 2007
  • Kinematic and kinetic analysis has been performed for Soft Golf swings utilizing realistic three dimensional computer simulations based on three dimensional motion tracking data. Soft Golf is a newly developed recreational sport in South Korea aimed to become a safe and easy-to-learn sport for all ages. The advantage of Soft Golf stems from lighter weight of the club and much larger area of the sweet spot. This paper tries to look into kinematic and kinetic aspects of soft golf swings compared to regular golf swing and find the advantages of lighter Soft Golf clubs. For this purpose, swing motions of older aged participants were captured and kinematic analysis was performed for various kinematic parameters such as club head velocity, joint angular velocity, and joint range of motions as a pilot study. Kinetic analysis was performed by applying kinematic data to computer simulation models constructed from anthropometric database and the measurements from the participants. The simulations were solved using multi-body dynamics solver. Firstly, the kinematic parameters such as joint angles were obtained by solving inverse dynamics problem based on motion tracking data. Secondly, the kinetic parameters such as joint torques were obtained by solving control dynamics problem of making joint torque to follow pre-defined joint angle data. The results showed that mechanical loadings to major joints were reduced with lighter Soft Golf club.

Simplified Model of Wheel Type Dog-Horse Robot to Reduce Dynamic Analysis Time (차륜형 견마 로봇의 동역학 해석시간 단축을 위한 단순화 모델)

  • Kim, Young Jin;Jung, Samuel;Kim, Tae Yun;Yoo, Wan Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.2
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    • pp.157-165
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    • 2016
  • In wartime conditionsmilitary combat vehicles are required to be driven on rough roads that have significant obstacles. A wheel type dog-horse robot with a rotary suspension system was applied to overcome the obstacles. To achieve real-time analysis, a simplified model was proposed by using velocity transformations. Through comparison with the multi-body dynamics model, the efficiency and accuracy of the proposed modeling was proven.

DEVELOPMENT OF MISSION ADN SPACECRAFT DYNAMICS ANALYSIS SYSTEM FOR GEOSTATION COMMUNICATION SATELLITE (통신위성의 임무 및 위성체 동역학 해석 시스템 개발)

  • 공현철;김방엽;김정아;윤진원
    • Journal of Astronomy and Space Sciences
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    • v.15 no.1
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    • pp.251-260
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    • 1998
  • We consider the motion of the subsystems as separate bodies as well as the entire satellite for the attitude and orbit control of a communication satellite by multi-body modeling technique. Thus, the system, can be applied to a general communication satellite as well as a specific communication satellite, i. e. Koreasat I,II. The simulation results can be viewed by two-dimensional graphics and three-dimensional animation. The graphical user interface(GUI) makes its usage much simpler. We have simulated a couple of scenarios for Koreasat I,II which are being operated as geostationary communication satellites to verify the system performance.

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Evaluation of three-dimensional cole-cole parameters from spectral IP data

  • Yang Jeong-Seok;Kim Hee Joon
    • 한국지구물리탐사학회:학술대회논문집
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    • 2003.11a
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    • pp.383-389
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    • 2003
  • Clay minerals show a distinct induced-polarization phenomenon, which is one of the most important factors for predicting groundwater flow and contaminant transport. This paper presents a step-by-step process to estimate Cole-Cole parameters from spectral induced-polarization (IP) data measured on the surface of three-dimensional earth. First, the inversion of low-frequency resistivity survey data is made to identify the dc resistivity ${\rho}_dc$ of a volume having IP effects. The other parameters, chargeability m, time constant $\tau$, and frequency dependence c, are sought for the polarizable volume. Next, using multi-frequency data, c can be obtained as high or low asymptotes of the slope of log phase vs. log frequency. Further, for low m, intrinsic $\tau$ is approximated by apparent one, ${\tau}_a$, which is derived from the relation ${{\omega}{\tau}}_a$=1 at an angular frequency $\omega$, where the imaginary component of spectral IP data has an extreme value. Finally, to obtain intrinsic m a two-step linearized procedure has been derived. For a body of given $\tau$ and c, forward modeling with a progression of m values yields a plot of observed vs. intrinsic imaginary components for a frequency. Since this plot is essentially linear, to extract the intrinsic imaginary component is quite simple with an observed value. Using the plot of intrinsic imaginary component vs. m, intrinsic m is determined. We present a synthetic example to illustrate that the Cole-Cole parameters can be recovered from spectral IP data.

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Landing Stability Simulation of a 1/6 Lunar Module with Aluminum Honeycomb Dampers

  • Pham, Van Lai;Zhao, Jun;Goo, Nam Seo;Lim, Jae Hyuk;Hwang, Do-Soon;Park, Jung Sun
    • International Journal of Aeronautical and Space Sciences
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    • v.14 no.4
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    • pp.356-368
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    • 2013
  • The Korea Aerospace Research Institute plans to launch a lunar module by 2025, and so is carrying out a preliminary study. Landing stability on the lunar surface is a key design factor of a lunar module. In this paper, a 1/6 scale model of a lunar module is investigated, for its landing stability on non-level surfaces. The lunar module has four tripod legs, with aluminum honeycomb shock absorbers in each leg strut. ADAMS$^{TM}$, the most widely used multi-body dynamics and motion analysis software, is used to simulate the module's lunar landing. Three types of dampers in the struts (rigid, viscous, and aluminum honeycomb dampers), and two types of lunar surfaces (rigid and elastic) are considered. The Sforce function is adopted, to model the aluminum honeycomb dampers. Details on the modeling and analysis of the landing stability of the 1/6 scale lunar module and the simulation results are provided in this paper.

Fast fabrication of amphibious bus with low rollover risk: Toward well-structured bus-boat using truck chassis

  • Mehrmashhadi, Javad;Mallet, Philippe;Michel, Paul;Yousefi, Amin Termeh
    • Smart Structures and Systems
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    • v.24 no.4
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    • pp.427-434
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    • 2019
  • This study investigates the structural integrity of the amphibious tour bus under the rollover condition. The multi-purpose bus called Dual Mode Tour Bus (DMTB) which explores on land and water has been designed on top of a truck platform. Prior to the fabrication of new upper body and sailing equipment of DMTB, computational analysis investigates the rollover protection of the proposed structure including superstructure, wheels, and axles. The Computer-Aided Design (CAD) of the whole vehicle model is meshed and preprocessed under high performance using the Altair HyperMesh to attain the best mesh model suited for finite element analysis (FEA) on the proposed system. Meanwhile, the numerical model is analyzed by employing LS-DYNA to evaluate the superstructure strength. The numerical model includes detail information about the microstructure and considers wheels and axles as rigid bodies but excludes window glasses, seats, and interior parts. Based on the simulation analysis and proper modifications especially on the rear portion of the bus, the local stiffness significantly increased. The vehicle is rotated to the contact point on the ground based on the mathematical method presented in this study to save computational cost. The results show that the proposed method of rollover analysis is highly significant not only in bus rollover tests but in crashworthiness studies for other application. The critical impartments in our suggested dual-purpose bus accepted and passed "Economic Commission for Europe (ECE) R66".

Modeling and Analysis of Interactions Between A Satellite and Variable-Speed Control Moment Gyros (인공위성과 가변속 제어모멘트자이로의 상호작용 모델링 및 해석)

  • Jin, Jaehyun;Leeghim, Henzeh
    • Journal of Aerospace System Engineering
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    • v.12 no.1
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    • pp.17-26
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    • 2018
  • The interaction model between variable-speed control moment gyros and a satellite has been studied based on the multi-body dynamics. Using the interaction model, we could obtain data for the design of VCMG motors and the strength design of structure. The interaction effects of flexible modules such as solar panels were included. Flexible modes are excited by the satellite's maneuver, and these modes cause perturbations in the satellite attitude. We developed a simulation program by Modelica and verified the proposed model.