• Journal of the Korean Society of Physical Medicine
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• v.15 no.3
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• pp.117-125
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• 2020

PURPOSE: Aging causes changes in the postural alignment and gait due to changes in the nervous and musculoskeletal systems. On the other hand, the relationship between the changes in posture alignment and gait is unclear. This study examined the relationship between the postural alignment and spatiotemporal gait parameters in Korean elderly women. METHODS: Thirty-two-healthy elderly women participated in this study. All subjects were assessed for their posture alignment and gait ability. Stepwise multiple linear regression was performed to determine to what extent the postural alignments could explain the spatiotemporal gait parameters. RESULTS: Coronal head angle was moderately correlated with the velocity (r = -.51), normalized velocity (r = -.46) and gait-stability ratio (r = .58) (p < .05). The trunk angle was moderately correlated with the normalized velocity (r = -.32) and gait-stability ratio (r = .32) and weakly correlated with the velocity (r = -.28) (p < .05). The coronal shoulder angle was moderately correlated with the swing phase (r = -.57), stance phase (r = .56), single limb stance (r = -.56) and double limb stance (r = .51) (p < .05). The coronal head angle and trunk angle accounted for 36% of the variance in velocity, 33% variance in normalized velocity and 46% variance in the gait-stability ratio (p < .05). The coronal shoulder angle accounted for 32% variance in the swing phase, 32% variance in the stance phase, 31% variance in the single limb stance and 26% variance in the double limb stance (p < .05). CONCLUSION: Changes in posture alignment in elderly women may serve as a biomarker to predict a decrease in walking ability due to physical aging.

• Journal of Korea Multimedia Society
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• v.18 no.11
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• pp.1400-1407
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• 2015

In the paper, we suggest bettered EHMECS(Enhanced Hybrid Multi Electrical Cupping System) to regulate automatically vacuum pressure using many cupping cup at once. We controlled accurately the pressure using S-PI control technique in pump motor to input the air inside cupping cup. S-PI control compared constant velocity, load and velocity variance between existing PI and FLC(Fuzzy Logic Control). The stabilization time of suggested S-PI control improve 20% of existing PI and 8% of FLC. The error constant of normal condition improved 71% of existing PI and 62% of FLC in steady speed and 80% of existing PI and 67% of FLC in load change. Also the error constant about velocity variance improve 45% of PI control. It is prove the suggested S-PI control technique. When use long time vacuum pressure of cupping cup regulated the suggested S-PI control technique, can loosen knotted muscles.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.1
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• pp.14-20
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• 1996

This paper presents a self tuning method of a velocity type PID controller for minimum or non-minimum phase systems with time delays. The velocity type PID control structure is determined in the process of minimizing the variance of the auxilliary output, and self tuning effect is achieved through the recursive least square algorithm at the parameter estimation stage and also through the Robbins-Monro algorithm at the stage of optimizing a design parameter. This method is simple and effective compared with other existing methods[1,2]. Numerical examples are included to illustrate the procedure and to show the performance of the control system.

• Fibers and Polymers
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• v.7 no.4
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• pp.424-431
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• 2006

Roll drafting, a mechanical operation attenuating fiber bundles to an appropriate thickness, is an important operation unit for manufacturing staple yams. It influences not only the linear density regularity of the slivers or staple yams that are produced, but also the quality of the textile product and the efficiency of the thereafter processes. In this research, the dynamic states of the fiber bundle in the roll drafting zone were analyzed by simulation, based on the mathematical model that describes the dynamic behavior of the flowing bundle. The state variables are the linear density and velocity of the fiber bundles and we simulated the dynamics states of the bundle flow, e.g., the profiles of the linear density and velocity in the draft zone for various values of the model parameters and boundary conditions, including the initial conditions to obtain their influence on the dynamic state. Results showed that the mean velocity profile of the fiber bundle was strongly influenced by draft ratio and process speed, while the input sliver linear density has hardly affected the process dynamics. Velocity variance of individual fibers that could be supposed to be a disturbing factor in drafting was also influenced by the process speed. But the major disturbance occurred due to the velocity slope discontinuity at the front roll, which was strongly influenced by the process speed. Thickness of input sliver didn't play any important role in the process dynamics.

• Structural Engineering and Mechanics
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• v.6 no.6
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• pp.673-691
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• 1998

In this paper, an analytic method to examine the random vibration of multispan Timoshenko frames due to a concentrated load traversing at a constant velocity is presented. A load's magnitude is a stationary process in time with a constant mean value and a variance. Two types of variances of this load are considered: white noise process and cosine process. The effects of both velocity and statistical characteristics of load and span number of the frame on both the mean value and variance of deflection and moment of the structure are investigated. Results obtained from a multispan Timoshenko frame are compared with those of a multispan Bernoulli-Euler frame.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.517-521
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• 2009

A unsteady internal ballistic analysis model was proposed to take account for the variance of local variance of pressure and velocity along the grain surface of a hybrid rocket combustor. The model of concern in the study was fairly comparable with the test result. The local variation of the oxidizer mass flow rate along grain surface results in chamber pressure, regression rate, and gas velocity change along its flow direction.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.4
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• pp.451-460
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• 1983

Computational four-equation turbulence model is developed and is applied to predict twodimensional unsteady thermal surface discharge into a reservoir. Turbulent stresses and heat fluxes in the momentum and energy equations are determined from transport equations for the turbulent kinetic energy (R), isotropic rate of kinetic energy dissipation (.epsilon.), mean square temperature variance (theta. over bar $^{2}$), and rate of destruction of the temperature variance (.epsilon. $_{\theta}$). Computational results by four-equation model are favorably compared with those obtained by an extended two-equation model. Added advantage of the four-equation model is that it yields quantitative information about the ratio between the velocity time scale and the thermal time scale and more detailed information about turbulent structure. Predicted time scale ratio is within experimental observations by others. Although the mean velocity and temperature fields are similarly predicted by both models, it is found that the four-equation model is preferably candidate for prediction of highly buoyant turbulent flows.

• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.101-114
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• 2003

The purpose of this study was to examine the major kinematicak variance to Increase the club head velocity during the driver swing two PGA prp-golfers utilizing 3-dimensional Image analyzing linear velocity of the club-head during the impact quantiatively. To achive these purpose, two high speed camera in 120 field/s and one high-speed camera in 500 field/s were used in this study. The program made by Younghoo Kwon(1944) was used to analysis the digitalization of reference point, digitalization of joint venter, synchronization, calculation of 3-Dimensional coordinate by DLT method, and smoothing. Through this study, the conclusions are as follow. 1. During the drivel swing, in the percentile of the total time, two pro-golfer showed 0.925, 0.929 second from adress to top-swing, 0.236, 0.929 second from top-swing to impact. 2. During the driver swing, in the displacement of the center of the body, two pro-golfer showed 45.3, 45.23% from adress, 44.3, 44.24% front impact. 3. In the velocity variance, The maximum club-head velocity two pro-golfer showed 43.36, 43.24m/s respectively the down swing. The ball velocity showed 63.12, 63.06m/s. 4. In the rotational angle of the shoulder joint. two pro-golfer showed $-13.5,-13.53^{\circ}$, during the back swing respectively. Two subject adressed opening status og upper body. 5. In the rotational angle of the right knee angle showed $156.3,154.7^{\circ}$ from the adress.

• Journal of Korea Water Resources Association
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• v.42 no.11
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• pp.897-909
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• 2009

The relative contribution of between hillslope-flow and stream-flow by heterogeneity of drainage path are quantitatively assessed in the present study with GIUH model based on grid of GIS. Application watersheds are selected Pyeongchang, Bocheong and Wi river basin of IHP in Korea. The mean and variance of hillslope and stream length are estimated and analyzed in each watershed. And coupling with observation storm events, estimate hillslope and stream characteristic velocity which dynamic parameters of GIUH model. The mean and variance of distribution of travel time (i.e. IUH) calculate using estimated pass lengths and characteristic velocities. And the relative contributions are assessed by heterogeneity of drainage path. As a result, the effect of the variance that determine shape of IUH dominate with hillslope's effect in the small watershed area (within 500 $km^2$). Thus, GIUH in the small watershed area must consider hillslope-flow.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.10a
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• pp.242-249
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• 1995

In order to search more efficient structural control algorithm, several closed-loop algorithm are developed. Among those, feedback control algorithm using parameters as displacement velocity, and acceleration has been studied. In this paper, especially the characteristics of accleration feedback is studied as more efficient control algorithm than any others. Furthermore the fact that ATMD with acceleration feedback system further reduce the variance of structural displacement rather than with displacement or velocity feedback system will be examined and proved.