• Title/Summary/Keyword: end-point model

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A Study on the Evaluation of Head Restraint System in Domestic Cars (국내생산차량의 시트 머리구속장치 평가에 관한 연구)

  • 조휘창;박인송;김영은
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.1
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    • pp.99-105
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    • 2004
  • The car seat head restraint is used for neck injury(whiplash injury) prevention in rear end impacts. The purpose of this study was to evaluate the seat head restraints for the total number of 34 domestic cars. H-POINT machine and HRMD(head restraint measuring device) were applied to measure backset(the distance between head and seat head restraint) and height(height gap between head and seat head restraint). For tendency study of driver's head position, we took the 320 driver's pictures in the street. As results, There were only five percent drivers in good and acceptable zone. For car seat head restraint system, the results was 9 cars for good zone, 10 cars for acceptable zone, 9 cars for marginal zone and 6 cars for poor zone were evaluated. For a precise evaluation the of whiplash injury, detailed FE neck model will be developed and the clinical database should be constructed for model validation.

Crack detection method for step-changed non-uniform beams using natural frequencies

  • Lee, Jong-Won
    • Smart Structures and Systems
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    • v.30 no.2
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    • pp.173-181
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    • 2022
  • The current paper presents a technique to detect crack in non-uniform cantilever-type pipe beams, that have step changes in the properties of their cross sections, restrained by a translational and rotational spring with a tip mass at the free end. An equation for estimating the natural frequencies for the non-uniform beams is derived using the boundary and continuity conditions, and an equivalent bending stiffness for cracked beam is applied to calculate the natural frequencies of the cracked beam. An experimental study for a step-changed non-uniform cantilever-type pipe beam restrained by bolts with a tip mass is carried out to verify the proposed method. The translational and rotational spring constants are updated using the neural network technique to the results of the experiment for intact case in order to establish a baseline model for the subsequent crack detection. Then, several numerical simulations for the specimen are carried out using the derived equation for estimating the natural frequencies of the cracked beam to construct a set of training patterns of a neural network. The crack locations and sizes are identified using the trained neural network for the 5 damage cases. It is found that the crack locations and sizes are reasonably well estimated from a practical point of view. And it is considered that the usefulness of the proposed method for structural health monitoring of the step-changed non-uniform cantilever-type pipe beam-like structures elastically restrained in the ground and have a tip mass at the free end could be verified.

Design of a Korean Speech Recognition Platform (한국어 음성인식 플랫폼의 설계)

  • Kwon Oh-Wook;Kim Hoi-Rin;Yoo Changdong;Kim Bong-Wan;Lee Yong-Ju
    • MALSORI
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    • no.51
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    • pp.151-165
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    • 2004
  • For educational and research purposes, a Korean speech recognition platform is designed. It is based on an object-oriented architecture and can be easily modified so that researchers can readily evaluate the performance of a recognition algorithm of interest. This platform will save development time for many who are interested in speech recognition. The platform includes the following modules: Noise reduction, end-point detection, met-frequency cepstral coefficient (MFCC) and perceptually linear prediction (PLP)-based feature extraction, hidden Markov model (HMM)-based acoustic modeling, n-gram language modeling, n-best search, and Korean language processing. The decoder of the platform can handle both lexical search trees for large vocabulary speech recognition and finite-state networks for small-to-medium vocabulary speech recognition. It performs word-dependent n-best search algorithm with a bigram language model in the first forward search stage and then extracts a word lattice and restores each lattice path with a trigram language model in the second stage.

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A Study on Evaluation and Analysis for IP VPN Model in IPv6 Transition Environment (IPv6 전이 환경에서 IP VPN 모델 분석과 평가에 대한 연구)

  • Kim, Hyung-J.;Yang, Jin-S.;Lee, Eun-S.;Kim, Hee-S.;Kim, Tae-K.;Chung, Tai-M.
    • The KIPS Transactions:PartC
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    • v.11C no.5
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    • pp.633-644
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    • 2004
  • For a smooth transition from IPv4 to IPv6 network, the research of transition mechanisms have been processing according to the various network situations. Therefore, we calculate the cost based on the VPN applicable model. Also, we present that conformance between the end point of VPN, the If encapsulation tunneling, applying position of translation mechanism and VPN applicable model are the factors which affect Costs.

A LNG Pressure Vessel Design (LNG 압력용기의 설계)

  • 김정위
    • Journal of Welding and Joining
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    • v.18 no.4
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    • pp.28-37
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    • 2000
  • In this paper the LNG vessel of the Moss type which is capable of lifting 15,261 tons is investigated in the view point of the pressure vessel preliminary design using the finite element method. The Pressure vessel design is based on the equivalent stress levels due to the internal pressure. The finite element model of the spherical pressure vessel is configured using 4 noded quadrilateral shell element. The finite element analysis program NASTRAN and ANSYS 5.5are implemented. The design is compared with the three kinds of the boundary condition : first, where the equator of the pressure vessel is fixed, and where the top and is fixed, and, the bottom end is fixed, respectively. A comparison is presented between the results obtained by the finite element model and by the prototype production model. Additionally just below position(case 1 & case 2) of equator ring was carried out by using ANSYS 5.5. The results show that the vessel design based on the stress is acceptable at the preliminary design.

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Force Tracking Control of a Small-Sized SMA Gripper H$_\infty$ Synthesis (H$_\infty$ 제어기법을 적용한 소형 SMA 그립퍼의 힘 추적 제어)

  • 한영민;최승복;정재천
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.391-395
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    • 1996
  • This paper presents a robust force tracking control of a small-sized SMA gripper with two fingers using shape memory alloy(SMA) actuators. The mathematical governing equation of the proposed system is derived by Hamilton's principle and Lagrangian equation and then, the control system model is integrated with the first-order actuator dynamics. Uncertain system parameters such as time constant of the actuators are also included in the control model. A robust two degree of freedom(TDF) controller using H$_{\infty}$ control theory, which has inherent robustness to model uncertainties and external disturbances, is adopted to achieve end-point force tracking control of the two-finger gripper. Force tracking control performances for desired trajectories represented by sinusoidal and step functions are evaluated by undertaking both simulation and experimental works.

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Nonlinear Analysis of RC Beams under Cyclic Loading Based on Moment-Curvature Relationship. (모멘트-곡률 관계에 기초한 반복하중을 받는 철근콘크리트 보의 비선형 해석)

  • 곽효경;김선필
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2000.10a
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    • pp.190-197
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    • 2000
  • A moment-curvature relationship to simulate the behavior of reinforced concrete beam under cyclic loading is introduced. Unlike previous moment-curvature models and the layered section approach, the proposed model takes into consideration the bond-slip effect by using monotonic moment-curvature relationship constructed on the basis of the bond-slip relation and corresponding equilibrium equation at each nodal point. In addition, the use of curved unloading and reloading branches inferred from the stress-strain relation of steel gives more exact numerical result. The advantages of the proposed model, comparing to layered section approach, may be on the reduction in calculation time and memory space in case of its application to large structures. The modification of the moment-curvature relation to reflect the fixed-end rotation and pinching effect is also introduced. Finally, correlation studies between analytical results and experimental studies are conducted to establish the validity of the proposed model.

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Dynamic behavior of boring bar with continuous system analysis (연속계 해석에 의한 보오링 바의 동적 거동에 관한 연구)

  • Kim, Jeong-Suk;Kang, Myeong-Chang;Park, Soo-Kil
    • Journal of the Korean Society for Precision Engineering
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    • v.11 no.4
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    • pp.38-46
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    • 1994
  • The vibration amplitude of boring bar is generally large at the tool tip, because it has the high length-diameter(L/D) ratio. A new dynamic cutting force model is presented by considering the change of shear angle under dynamic cutting. The boring bar is modelled as a cantilever with dynamic force acting at the tool end point. Based on this realistic continuous system model, the equation of motion of borring bar is solved by numerical computations. A good agreement is found between the proposed model and the experimental results.

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Control of a mobile robot supporting a task robot on the top

  • Lee, Jang M.
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10a
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    • pp.1-7
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    • 1996
  • This paper addresses the control problem of a mobile robot supporting a task robot with needs to be positioned precisely. The main difficulty residing in the precise control of a mobile robot supporting a task robot is providing an accurate and stable base for the task robot. That is, the end-plate of the mobile robot which is the base of the task robot can not be positioned accurately without external position sensors. This difficulty is resolved in this paper through the vision information obtained from the camera attached at the end of a task robot. First of all, the camera parameters were measured by using the images of a fixed object captured by the camera. The measured parameters include the rotation, the position, the scale factor, and the focal length of the camera. These parameters could be measured by using the features of each vertex point for a hexagonal object and by using the pin-hole model of a camera. Using the measured pose(position and orientation) of the camera and the given kinematics of the task robot, we calculate a pose of the end-plate of the mobile robot, which is used for the precise control of the mobile robot. Experimental results for the pose estimations are shown.

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Biped Walking of a Humanoid Robot for Argentina Tango

  • Ahn, Doo-Sung
    • Journal of Drive and Control
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    • v.13 no.4
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    • pp.52-58
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    • 2016
  • The mechanical design for biped walking of a humanoid robot doing the Argentina Tango is presented in this paper. Biped walking has long been studied in the area of robotic locomotion. The aim of this paper is to implement an Argentina Tango dancer-like walking motion with a humanoid robot by using a trajectory generation scheme. To that end, this paper uses blending polynominals whose parameters are determined based on PSO (Particle Swarm Optimization) according to conditions that make the most of the Argentina Tango's characteristics. For the stability of biped walking, the ZMP (Zero Moment Point) control method is used. The feasibility of the proposed scheme is evaluated by simulating biped walking with the 3D Simscape robot model. The simulation results show the validity and effectiveness of the proposed method.