• Title/Summary/Keyword: Acceleration time

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Cooperative Manipulation of a Virtual Object by Multiple Remote Users

  • Choi, Hyouk-Ryeol;Ryew, Sung-Moo
    • Journal of Mechanical Science and Technology
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    • 제14권9호
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    • pp.956-967
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    • 2000
  • In this paper, we explore the issues of force display in the cooperative virtual environment shared by multiple users distributed over the network with heterogeneous hardware platforms. The proposed method is to cope with the problem of small time delay and the difference of sampling rate in the distributed configuration. In the proposed approach the interaction forces of the participants are just treated as the independent sources of acceleration. Thus the action of a participant simply changes the acceleration of the virtual object and consequently the states of the virtual object will be updated. When the updated states are reported to all the participants, the information on the time of state changes is delivered, too. Employing the discrete state information updated by the other users, each user modifies his own virtual environment and pseudo-realtime simulation can be realized. Excluding the software interface and the communication technique, it is proposed the simulation method for the operation of respective users and the way of calculating the driving input to the display device. For experimental verification we construct a cooperative virtual environment shared by two remote users and outline the results of experiments.

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진동대 실험을 통한 암반비탈면의 변위 거동 특성 (Displacements Behavior of Rock Slope by Shaking Table Test)

  • 윤원섭;강종철;박연준
    • 한국산업융합학회 논문집
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    • 제23권2_2호
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    • pp.245-254
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    • 2020
  • This study investigated the so far little-researched characteristics of the behaviors of rock slopes at the time of an earthquake. For the selection of the rock block, a proper model was formed by applying the similarity in consideration of the roughness and strength of the rock slope(10m) on the site, and shaking table tests were carried out according to seismic excitement acceleration, and seismic waves. In the case of the inclination angle of the joint plane of 20°, the long period wave at 0.3g or more at the time of the seismic excitement surpassed the length of 100mm, the permissible displacement (0.01H, H:slope height), which brought about the collapse of the rock; the short period wave surpassed the permissible displacement at 0.1g, which caused the collapse of the slope. The rock slope was close to a rigid block and a structure more vulnerable to the long period wave than to the short period wave. It collapsed in the short period wave even at the seismic amplitude smaller than the maximum design acceleration in Korea.

브러시리스 직류전동기의 정속도 운전을 위한 디지털 PI제어 (The Digital PI Control for Driving Constant Speed of Brushless DC Motor)

  • 윤신용;김현수;김용;김일남;백수현
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제49권6호
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    • pp.395-402
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    • 2000
  • This paper presents the improvement for speed characteristics of a Brushless DC Motor (BLDCM), it was applied to digital PI control for this. The practical PID control has been widely used to velocity control of DC motors. In this paper, a digital PI controller is used in order to decrease the speed error in constant velocity control of BLDCM. A TMS320C31 DSP is used for the microprocessor of digital PI control. The method using the DSP carry out the real-time control. The DSP has the rapid calculation ability and sampling time used lms. Driving BLDCM used 50W, motor input DC 150V and rotation speed 3000rpm. When BLDCM is to approval for discretion velocity at the acceleration and deceleration driving with any load, it was a feasible for stabilization control. Therefore, the experimental results indicate the superiority and validity of the velocity control by digital PI control.

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발성이 작업수행 중 상지 움직임에 미치는 영향 (Effects of Vocalization on Upper Extremity Motion During Occupational Performance)

  • 박지혁;유은영;신수정;신혜경;김진경
    • 한국전문물리치료학회지
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    • 제11권1호
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    • pp.75-83
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    • 2004
  • The purpose of this study was to research the effects of vocalization on upper extremity motion during occupational performance and to compare non-meaning and meaning vocalization. Experiments were performed on 30 subjects. They had no medical history of neurological problems with their upper extremities. Using a tea cup, a tea tray, and a tea spoon, they set a table during vocalization. We used meaning and non-meaning vocalization with the subjects. An example of meaning vocalization would be naming something, and an example of non-vocalization would be saying, "Ah." We used a 3-D analysis system called CMS-HS. We analyzed the motion in the angular velocity and acceleration of the elbow while recording performance time. The results of this study showed that vocalization enhanced the angular velocity and acceleration of the elbow, and also enhanced performance time. In short, vocalization improved upper extremity motion by making it faster and smoother. There were no significant differences between meaning and non-meaning vocalization.

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Experimental analysis of whiplash injury with hybrid III 50 percentile test dummy

  • Gocmen, Ulas;Gokler, Mustafa Ilhan
    • Advances in Automotive Engineering
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    • 제1권1호
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    • pp.61-77
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    • 2018
  • In this study, the effects of sitting position of the driver on the whiplash neck injury have been analyzed experimentally by using hybrid III series 50 percentile male crash test dummy. A testing platform consisting of vehicle ground, driver foot rest, driver seat and a 3-point seatbelt has been prepared. This testing platform and the instrumented crash test dummy are prepared for tests according to the Euro NCAP whiplash testing protocol. The prepared test set-up has been exposed to 3 different acceleration-time loading curves defined in the Euro NCAP whiplash testing protocol by performing sled tests. 9 different sled tests have been performed with the combinations of 3 different seating positions of the crash test dummy and 3 different acceleration-time loading curves. The sensor data obtained from the crash test dummy and high-speed videos taken are analyzed according to the injury assessments criteria defined in the Euro NCAP whiplash testing protocol and the criticality of the whiplash injury is defined. It is seen that the backset distance of the driver head with the headrest and the height difference of the top of the head of the driver with the headrest have a great importance on whiplash injuries.

전자 패키징 소재의 수착 특성화를 통한 신뢰성 평가 (Reliability Evaluation Through Moisture Sorption Characterization of Electronic Packaging Materials)

  • 박희진
    • 대한기계학회논문집A
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    • 제37권9호
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    • pp.1151-1158
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    • 2013
  • 습기 수착 물성은 전자 패키징 장치의 신뢰성에 있어서 층간의 수증기 압력에 의해 공정과정 동안 발생되는 박리 불량의 고장 분석 및 최적의 재료 개발에 있어서 필수적이다. 본 논문에서는 온습도 모델에 따른 전자 패키징 재료의 온도 의존적인 흡습 및 탈습 물성을 변수화 하였고 이에 대한 온도 및 습도의 영향에 대해 고찰하였다. 변수화된 확산성에서 얻어진 확산 활성화 에너지는 등가의 습기 수착 수준을 위한 가속 수명 비율을 결정하고 신뢰 수명 평가에 요구되는 등가의 소요 시험 시간에 미치는 습기 확산성의 영향을 예측할 수 있게 한다. 신뢰성 시험 표준에서 평가된 유연 전자 모듈의 가속 수명비율을 예시하였다.

Dynamic displacement estimation by fusing biased high-sampling rate acceleration and low-sampling rate displacement measurements using two-stage Kalman estimator

  • Kim, Kiyoung;Choi, Jaemook;Koo, Gunhee;Sohn, Hoon
    • Smart Structures and Systems
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    • 제17권4호
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    • pp.647-667
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    • 2016
  • In this paper, dynamic displacement is estimated with high accuracy by blending high-sampling rate acceleration data with low-sampling rate displacement measurement using a two-stage Kalman estimator. In Stage 1, the two-stage Kalman estimator first approximates dynamic displacement. Then, the estimator in Stage 2 estimates a bias with high accuracy and refines the displacement estimate from Stage 1. In the previous Kalman filter based displacement techniques, the estimation accuracy can deteriorate due to (1) the discontinuities produced when the estimate is adjusted by displacement measurement and (2) slow convergence at the beginning of estimation. To resolve these drawbacks, the previous techniques adopt smoothing techniques, which involve additional future measurements in the estimation. However, the smoothing techniques require more computational time and resources and hamper real-time estimation. The proposed technique addresses the drawbacks of the previous techniques without smoothing. The performance of the proposed technique is verified under various dynamic loading, sampling rate and noise level conditions via a series of numerical simulations and experiments. Its performance is also compared with those of the existing Kalman filter based techniques.

Dynamic Response Measurement of the Head Arm Assembly of a Hard Disk Drive by Numerical Analysis and Experiments

  • Parlapalli, Madhusudhana R;Bin, Gu;Dongwei, Shu;Fujii, Yusaku
    • International Journal of Precision Engineering and Manufacturing
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    • 제9권4호
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    • pp.22-25
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    • 2008
  • The dynamic response of the head arm assembly (HAA) of a hard disk drive to an impact load was obtained from a 3D non-linear finite element model using ANSYS/LS-DYNA and from experiments using a modified levitation mass method (LMM). In the finite element model, the impact load was created by modeling the mass as a rigid body and making it collide with the HAA. The velocity, displacement, acceleration, and inertial force of the mass were then obtained from the time history data of the finite element analysis. In the LMM, a mass that was levitated with an aerostatic linear bearing, and hence encountered negligible friction, was made to collide with the actuator arm, resulting in a dynamic bending test for the arm. During the collision, the Doppler frequency shift of the laser beam reflected from the mass was accurately measured with an optical interferometer. The velocity, displacement, acceleration, and inertial force of the mass were accurately calculated from the measured time-varying Doppler frequency shift. A good correlation between the experimental data and FEA results was observed. The FEA was also used to investigate the dynamic response of the HAA to impact by different masses.

충돌회피를 위한 가속도를 고려한 차선 변경 시스템 개발 (Development of Lane Change System considering Acceleration for Collision Avoidance)

  • 강현구;이동휘;허건수
    • 한국자동차공학회논문집
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    • 제21권2호
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    • pp.81-86
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    • 2013
  • This paper presents the lane change system for collision avoidance. The proposed algorithm for the collision avoidance consists of path generation and path following. Using a calculated TTC (Time to Collision), partial braking is operated and collision avoidance path is generated considering relative distance, velocity and acceleration. Based on the collision avoidance path, desired yaw angle and yaw rate are calculated for the automated path following. The lateral controller is designed by a Lyapunov function approach using 3 D.O.F vehicle model and vehicle parameters. The required steering angle is determined from wheel velocity, longitudinal and lateral velocity in order to follow the desired yaw angle and yaw rate. This system is developed MATLAB/Simulink and its performance is evaluated using the commercial software CarSim.

Relationship between Aiming Patterns and Scores in Archery Shooting

  • Quan, ChengHao;Lee, Sangmin
    • 한국운동역학회지
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    • 제26권4호
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    • pp.353-360
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    • 2016
  • Objective: The aim of this study was to investigate the relationship between aiming patterns and scores in archery shooting. Method: Four (N = 4) elementary-level archers from middle school participated in this study. Aiming pattern was defined by averaged acceleration data measured from accelerometers attached on the body during the aiming phase in archery shooting. Stepwise multiple regression analysis was used to test whether a model incorporating aiming patterns from all nine accelerometers could predict the scores. In order to extract period of interest (POI) data from raw data, a Dynamic Time Warping (DTW)-based extraction method was presented. Results: Regression models for all four subjects are conducted with different significance levels and variables. The significance levels of the regression models are 0.12%, 1.61%, 0.55%, and 0.4% respectively; the $R^2$ of the regression models is 64.04%, 27.93%, 72.02%, and 45.62% respectively; and the maximum significance levels of parameters in the regression models are 1.26%, 4.58%, 5.1%, and 4.98% respectively. Conclusion: Our results indicated that the relationship between aiming patterns and scores was described by a regression model. Analysis of the significance levels, variables, and parameters of the regression model showed that our approach - regression analysis with DTW - is an effective way to raise scores in archery shooting.