• Title/Summary/Keyword: frequency-response

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An Improved FES System for Control of Paralyzed Upper Extremity

  • Ryoo, Young-Jae;Kim, Young-Min;Park, Chul-Soo;Park, Bong-Kee;Lim, Young-Chul
    • Proceedings of the KOSOMBE Conference
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    • v.1993 no.05
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    • pp.120-122
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    • 1993
  • This paper describes an improved FES system to restore paralyzed extremities in spinal cord injury patients. For composing stimulus pattern which is suitable for each muscle, electrical stimulus pattern creating system is also developed by using IBM-PC. In the improved portable FES system using V40 microprocessor, muscle fatigue can be decreased by selecting the stimulus frequency which is proper to the response characteristics of each muscle. Driving softwares for the portable FES system and the stimulus pattern creating system are programmed with assembler and C language. A multichnnel portable FES system is designed to minimize the sire and weight using a D/A converter and 32 channel multiplexer.

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Internet Access and Use among Students of Physical Education: A Study of Kurukshetra University, Kurukshetra

  • Kumar, Rajender
    • Journal of Information Science Theory and Practice
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    • v.2 no.2
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    • pp.59-68
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    • 2014
  • This paper depicts a study conducted on the behavior of physical education students towards Internet usage at Kurukshetra University, Kurukshetra. Specially, the study aims to know the purposes for use of Internet resources and services, frequency of use, places and means of use, student's satisfaction level toward the Internet, and problems faced while using the Internet. A survey was carried out with a sample of 100 physical education students of Kurukshetra University and the response rate was 88%. A well-designed questionnaire was distributed to the students' sample. Amazingly, the results of the study reveal that usage of the Internet in research and education was not favored, whereas email, chatting, and sports websites were commonly used among students. The study also found that too much information on the Internet, slow access speeds, and finding relevant information were the main problems in using the Internet.

Methodology on Improving Vibration Characteristics of Servo Write Fixture (서보라이트 픽스쳐의 진동 특성 개선 방법)

  • Yoon, Tae-Yong;Ku, C.P. Roger;Hanlon, Andrew K.;Taylor, Charles L.
    • Transactions of the Society of Information Storage Systems
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    • v.7 no.2
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    • pp.47-52
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    • 2011
  • This paper presents a method to improve vibration characteristics of servo track write (STW) fixture. STW fixtures supported by flexible mounts are subject to various vibration sources. Using Finite element analysis (FEA) vibration modes of the fixture are identified. The FEA results suggest certain vibration modes be reduced through design change of flexible mounts to improve vibration responses of the fixture. Based on layered flexible mounts theory a parametric study on shear and bending stiffness is performed to obtain a suitable flexible mount design leading to increased resistance to rocking motion. Experiments confirm improvement of vibration characteristics and drive performance through new mounts design.

Modification of Radiation Response in Mice by Panax ginseng and Diethyldithiocarbamate

  • Kim, Sung-Ho;Son, Chang-Ho;Nah, Seung-Yeol;Jo, Sung-Kee;Byun, Myung-Woo;Shin, Dong-Ho
    • Proceedings of the Korean Society of Veterinary Pathology Conference
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    • 2001.09a
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    • pp.22-22
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    • 2001
  • We performed this study to determine the effect of Panax ginseng and its fractions on jejunal crypt survival, endogenous spleen colony formation, and apoptosis in jejunal crypt cells of mice irradiated with high and low dose of $\gamma$-irradiation. The radioprotective effect of ginseng was compared with the effect of diethyldithiocarbamate (DDC). Ginseng administration before irradiation protected the jejunal crypts (p<0.005), increased the formation of endogenous spleen colony (p<0.005) and reduced the frequency of radiation-induced apoptosis (p<0.005). (omitted)

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Design of a Robust Track-following Controller with Multiple Constraints (다중 제한 조건을 고려한 강인 트랙 추종 제어기의 설계)

  • Jin Kyoun Bog;Kim Jin-Soo;Lee Moon-Noh
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.9 s.90
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    • pp.827-836
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    • 2004
  • In this paper, we design a robust multi-objective track-following controller that satisfies transient response specifications and diminishes the influence of sinusoidal disturbance. To this end, a robust control problem with the multiple constraints is considered. We show that a sufficient condition satisfying the robust control problem can be expressed by linear matrix inequalities. Finally, the robust track-following controller can be designed by solving an LMI optimization problem. The effectiveness of the proposed controller design method is verified though experiments.

Generalized modal analysis of asymmetrical rotor system using modulated coordinates (변조 좌표계를 이용한 비대칭 회전체계의 일반화된 모드해석)

  • 서정환;홍성욱;이종원
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.526-531
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    • 2003
  • Conventional modal analysis techniques are known to be inappropriate for asymmetrical rotor systems. when the equations of motion are written in the stationary coordinates, due to the presence of time varying parameters. This paper presents a generalized modal analysis method for asymmetrical rotor systems in the stationary coordinates, employing the modulated coordinates and the lambda matrix formulation. A numerical example with a flexible asymmetric rotor model is provided to demonstrate the effectiveness of the proposed modal analysis method. As an application of the proposed method, modal analysis is also performed with an open cracked rotor system.

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Numerical Methods for Wave Response in Harbor (항만내의 파도 응답에 관한 수치 계산)

  • D.J.,Kim;K.J.,Bai
    • Bulletin of the Society of Naval Architects of Korea
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    • v.25 no.3
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    • pp.3-12
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    • 1988
  • A natural or an artificial harbor can exhibit frequency(or period) dependent water surface oscillations when excited by incident waves. Such oscillations in harbors can cause significant damage to moored ships and adjacent structures. This can also induce undesirable current in harbors. Many previous investigators have studied various aspects of harbor resonance problem. In the percent paper, both a localizes finite element method(LFEM) which is based on the functional constructed by Chen & Mei(1974) and Bai & Yeung(1974) and an integral equation method which was used by Lee(1969) are applied to harbor resonance problem. The present method(LFEM) shows computationally more efficient than the integral equation method. Our test results shows good agreement compared with other results. This enhanced computational efficiency is due to the fact that the present method gives a banded symmetric coefficients matrix and requires much less computational time in the calculation of the influence coefficients matrix than the integral equation method involved with Green's function. To test the present numerical scheme, two models are treated here. The present method(LFEM) can be extended to a fully three dimensional harbor problem with the similar computational advantage.

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Nonlinear Motion for an Elliptic Cylinder under Free Surface (자유표면 아래의 타원형 실린더에 대한 비선형 운동)

  • 이호영;임춘규
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.4
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    • pp.38-44
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    • 2004
  • The motion response analysis of a submerged elliptic cylinder in waves is presented and the elliptic cylinder is a simplification of the section of submarine in this paper. The method is based on boundary integral method and two-dimensional 3 degree motions are calculated in regular harmonic waves. The fully nonlinear free surface boundary condition is assumed in an numerical domain and this solution is matched along an assumed boundary as a linear solution composed of transient Green function, The large amplitude motions of an elliptic cylinder are directly simulated and effects of wave frequency, wave amplitude and the distance from buoyancy center to gravity center are discussed.

An Experimental Study on Validation of Nonlinear Critical Speed (비선형 임계속도 검증을 위한 실험적 연구)

  • 정우진;김성원
    • Journal of the Korean Society for Railway
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    • v.3 no.1
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    • pp.12-18
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    • 2000
  • This paper addresses the experimental study on the nonlinear critical speed and the validity of simple prediction formulation. The experiment on nonlinear critical speed is carried out using roller rigs, which has been impossible on track because of a possibility of an accident. In addition, experiment for a bogie is performed to check the difference in modeling a full railway vehicle and a bogie. It is found that nonlinear critical speed proves to be an inherent phenomenon of a railway vehicle itself and the difference of test results between a full railway vehicle and a bogie is comparatively negligible. Finally. the accuracy of simple prediction formulation for outbreak velocity and response frequency in hunting is investigated.

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Review on Pre-processing of Earthquake Data from KEPRI Seismic Monitoring System (전력연구원 지진관측자료의 사전자료처리 기법 및 효과적인 활용에 관한 고찰)

  • 연관희;박동희;최원학;장천중
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.2
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    • pp.39-50
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    • 2002
  • Several pre-processing techniques for earthquake data from earthquake monitoring institutes in Korea including Korea Electric Power Research Institute are thoroughly reviewed. Among these techniques for removing an instrumental response, removing the non-causal ringing distortion by FIR filter, checking calibration status of seismic stations, and minimizing the window effect are introduced and applied to real data. It is also recommended that analysts evaluate S/N ratio in the frequency domain and consider the possibility of using the saturated earthquake data.