• 대한물리의학회지
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• 제15권3호
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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.

• 한국멀티미디어학회논문지
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• 제18권11호
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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.

• 제어로봇시스템학회논문지
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• 제2권1호
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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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• 제7권4호
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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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• 제6권6호
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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.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.517-521
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• 2009

본 연구에서는 연소실의 축방향 압력과 속도변화를 도출할 수 있는 비정상 내탄도 해석모델을 개발하고 이를 바탕으로 산화제 변화에 따른 연소실 압력분포 변화를 해석할 수 있다. 개발 모델 검증을 위하여 연소실 전후단의 압력을 측정한 실험결과와 해석결과를 비교하여 실험과 해석결과가 유사함을 확인하였다. 하류방향으로 산화제 유량이 변하고 이는 연소실 압력 및 후퇴율, 연소가스 유속의 변화에 영향을 미침을 고찰하였다.

• 대한기계학회논문집
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• 제7권4호
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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.

• 한국운동역학회지
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• 제13권2호
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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.

• 한국수자원학회논문집
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• 제42권11호
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• pp.897-909
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• 2009

본 연구에서는 지리정보체계(GIS)의 격자 기반 GIUH 모형을 이용하여 배수경로의 이질성에 따른 지표면 유동과 하천망 유동의 상대적 기여도를 정량적으로 평가하였다. 대상유역은 국제수문개발계획(IHP)의 평창강, 보청천 및 위천 유역의 17개 소유역을 선정하였다. 각 대상유역에 대해 지표면과 하천의 배수경로길이에 대한 평균과 분산을 추정-분석하였다. 또한 관측 수문사상과 결합하여 GIUH 모형의 동적매개변수인 특성 유속을 지표면과 하천에 대해 산정하였다. 산정된 경로길이와 특성유속을 통해 유하시간의 분포, 즉 순간단위도의 평균 및 분산을 추정하여 배수경로의 이질성에 따른 각각의 기여도를 평가 하였다. 연구 결과 순간단위도의 형상을 결정하는 분산의 영향은 중소규모 유역(500 $km^2$이내)에서 지표면의 영향이 지배적이었다. 따라서 소규모 유역에서 GIUH 적용 시 지표면의 유동을 중요하게 고려해야 할 것이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1995년도 가을 학술발표회 논문집
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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.