• Title/Summary/Keyword: Vertical speed

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Vertical Limb Stiffness Increased with Gait Speed in the Elderly (노인군 보행 속도 증가에 따른 하지 강성 증가)

  • Hong, Hyun-Hwa;Park, Su-Kyung
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.6
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    • pp.687-693
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    • 2011
  • Spring-mass models have been widely accepted to explain the basic dynamics of human gait. Researchers found that the leg stiffness increased with gait speed to increase energy efficiency. However, the difference of leg stiffness change with gait speed between the young and the elderly has not been verified yet. In this study, we calculated the lower limb stiffness of the elderly using walking model with an axial spring. Vertical stiffness was defined as the ratio of the vertical force change to the vertical displacement change. Seven young and eight elderly subjects participated to the test. The subjects walked on a 12 meter long, 1 meter wide walkway at four different gait speeds, ranging from their self-selected speed to maximum speed randomly. Kinetic and kinematic data were collected using three force plates and motion capture cameras, respectively. The vertical stiffness of the two groups increased as a function of walking speed. Maximum walking speed of the elderly was slower than that of the young, yet the walking speed correlated well with the optimal stiffness that maximizes propulsion energy in both groups. The results may imply that human may use apparent limb stiffness to optimize energy based on spring-like leg mechanics.

The Effect of Change in Gait Speed on Vertical Force of the Cane and Distribution of Affected Foot in the Persons with Chronic Stroke (보행속도의 변화가 만성 뇌졸중 환자 지팡이의 수직력과 마비측 발의 체중지지에 미치는 영향)

  • Jung, Kyoung-Sim;Seo, Hyun-Du;Lee, Kwan-Woo;Chung, Yi-Jung
    • Journal of the Korean Society of Physical Medicine
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    • v.7 no.2
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    • pp.223-230
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    • 2012
  • Purpose : The purpose of this study was to analyze weight bearing of cane and affected foot at different speeds during walking. Methods : Thirteen subjects (6 males, 7 females) with stroke enrolled in the study. A foot sensor and an instrumented cane were integrated to analyze the vertical peak force on the affected foot and the cane. Results : The applied vertical peak force on the cane were $12.02{\pm}4.80%$ (slow speed), $7.97{\pm}3.95%$ (comfortable speed), and $6.86{\pm}3.30%$ (fast speed) body weight, respectively. The results indicated significantly lower vertical peak force on the affected foot in the low speed walking condition when compared to the fast walking (p<.05) and the comfortable walking (p<.05) conditions. The correlations between TUG and vertical peak force on the cane and affected foot were .71, and -.70 (p<.01). There was a higher correlation between the vertical peak force on the cane and affected foot were -.87(p<.01). Conclusion : In conclusion, slower walking speed applied greater vertical peak force on the cane. On the contray, slower walking speed applied less vertical peak force on the affected foot. Further studies, duration of force should be measured at different speeds during walking in lower and higher functioning hemiparetic subjects, as its use may mask underlying gait impairment.

Development of a Quality Check Algorithm for the WISE Pulsed Doppler Wind Lidar (WISE 펄스 도플러 윈드라이다 품질관리 알고리즘 개발)

  • Park, Moon-Soo;Choi, Min-Hyeok
    • Atmosphere
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    • v.26 no.3
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    • pp.461-471
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    • 2016
  • A quality check algorithm for the Weather Information Service Engine pulsed Doppler wind lidar is developed from a view point of spatial and temporal consistencies of observed wind speed. Threshold values for quality check are determined by statistical analysis on the standard deviation of 3-component of wind speed obtained by a wind lidar, and the vertical gradient of horizontal wind speed obtained by a radiosonde system. The algorithm includes carrier-to-noise ratio (CNR) check, data availability check, and vertical gradient of horizontal wind speed check. That is, data sets whose CNR is less than -29 dB, data availability is less than 90%, or vertical gradient of horizontal wind speed is less than $-0.028s^{-1}$ or larger than $0.032s^{-1}$ are classified as 'doubtful', and flagged. The developed quality check algorithm is applied to data obtained at Bucheon station for the period from 1 to 30 September 2015. It is found that the number of 'doubtful' data shows maxima around 2000 m high, but the ratio of 'doubtful' to height-total data increases with increasing height due to atmospheric boundary height, cloud, or rainfall, etc. It is also found that the quality check by data availability is more effective than those by carrier to noise ratio or vertical gradient of horizontal wind speed to remove an erroneous noise data.

Kinematic Analysis of Yeo Motion at Horse Vaulting (도마 Yeo동작에 대한 운동학적 요인 분석)

  • Yeo, Hong-Chul
    • Korean Journal of Applied Biomechanics
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    • v.13 no.1
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    • pp.39-50
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    • 2003
  • The purpose of this experiment was to find out the stages of result of specific character for Horse Vaulting Yeo motion To put the Yeo movement in process, we needed a gymnastics athlete C height of 165cm, weight of 62kg, age of 32, personal history of 21 years, and tested the athlete 5 times of motion training, and picked out the 2 best motion and analyzed it. Athletic reason is vertical motion, time uses, horizontal motion, distance, speed, and analyzed many other reasons as a result, and finally ended up with this conclusion. 1. After the take off on the board horizontal speed gradually decreased However, reverse of that, it showed that vertical speed increased. 2. While contacting the Horse Vaulting, horizontal speed decreased and vertical speed kept on increasing. Taking off Com the Horse Vaulting, horizontal, showing short time of training, 3m vertical height is shown after using Yeo motion at the peak of second fly jump. 3. While contacting the Horse Vaulting, both arms were showing the flection shape Especially this is also while contacting the Horse Vaulting, left arm was showing $90^{\circ}$ angle, and this has happened between the process of transition period of fast horizontal speed to vertical speed. 4. While contacting the Horse Vaulting, perfect blocking of the left arm must be complete for the right arm to have the perfect blocking as well.

A Development of the Operating Speed Estimation Model of Truck on Four-lane Rural Highway (지방부 일반국도 4차로의 화물차 주행속도 예측모형 개발)

  • Park, Min Ho;Lee, Geun Hee
    • International Journal of Highway Engineering
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    • v.16 no.5
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    • pp.173-182
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    • 2014
  • PURPOSES : The purpose of the study is to a) explore the operating speed of trucks on rural highways affected by road geometry, and thereby b) develop a predictive model for the operating speed of trucks on rural highways. METHODS : Considering that most of the existing studies have focused on cars, the current study aimed to predict the operating speed of trucks by conducting linear regression analysis on the speed data of trucks operating on the linear-curved-linear portions of the road as a single set. RESULTS : The operating speed in the plane curve portion increased with the length of the curve, and decreased with a lower vertical grade and a smaller curve radius. In the straight plane portion, the operating speed increased with a larger curve radius(upstream), and decreased with an increase in the change of the vertical grade, depending on the length of the vertical curve. CONCLUSIONS : This study developed estimation models of truck for operational speed and evaluated the degree of safety for horizontal and vertical alignments simultaneous. In order to represent whole area of the rural highway, the models should be ew-analyzed with vast data related with road alignment factor in the near future.

A design of vertical axis wind power generating system combined with Darrieus-Savonius for adaptation of variable wind speed (다변풍속 적응형 Darrieus-Sauonius 초합 수직푹 풍력발전 시스템의 설계)

  • 서영택;오철수
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.2
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    • pp.185-192
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    • 1996
  • This paper presents a design of vertical axis Darrieus wind turbine combine with Savonius for wind-power generating system to be adapted for variable wind speed. The wind turbine consists of two troposkien- and four Savonius-blades. Darrieus turbine is designed with diameter 9.4[m], chord length 380[mm], tip speed ratio 5. Savonius turbine is designed with diameter 1.8[m], height 2[m], tip speed ratio 0.95. The design of turbine is laid for the main data of rated wind speed 10[m/s], turbine speed 101.4[rpm]. The generating power is estimated to maximum power 20[kW], and this is converted to commercial power line by means of three phase synchronous generator-inverter system. Generating system is designed for operation on VSVF(variable speed variable frequency) condition and constant voltage system.

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The Evaluation of Structural Stability of Corrugated Steel Plate Method applied in High-Speed Railway Vertical Tunnel Structures (고속철도 수직구 터널구조물에 적용된 파형강판공법의 구조적 안정성 검토)

  • Chung, Jee-Seung;Shin, Hwa-Cheol;Kim, Jin-Gu
    • Journal of the Korean Society of Safety
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    • v.31 no.2
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    • pp.64-69
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    • 2016
  • In this paper, structural analysis of High-Speed railway vertical tunnel structures was performed to verify the structural stability. The corrugated steel plate method was applied to the vertical tunnel structures for its simple construction method and low cost. The structural stability of Wall, Connection and Storage section was performed with LRFD and ASD design method at joint part, buckling, stress and plastic hinge. From the results, all of vertical tunnel structures shown the structural stability regardless of design method and structure types. So, the application of corrugated steel plate in vertical tunnel structures instead of cast-in-placed concrete was quite enough.

Mapping vertical bridge deformations to track geometry for high-speed railway

  • Gou, Hongye;Ran, Zhiwen;Yang, Longcheng;Bao, Yi;Pu, Qianhui
    • Steel and Composite Structures
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    • v.32 no.4
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    • pp.467-478
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    • 2019
  • Running safety and ride comfort of high speed railway largely depend on the track geometry that is dependent on the bridge deformation. This study presents a theoretical study on mapping the bridge vertical deformations to the change of track geometry. Analytical formulae are derived through the theoretical analysis to quantify the track geometry change, and validated against the finite element analysis and experimental data. Based on the theoretical formulae, parametric studies are conducted to evaluate the effects of key parameters on the track geometry of a high speed railway. The results show that the derived formulae provide reasonable prediction of the track geometry change under various bridge vertical deformations. The rail deflection increases with the magnitude of bridge pier settlement and vertical girder fault. Increasing the stiffness of the fasteners or mortar layer tends to cause a steep rail deformation curve, which is undesired for the running safety and ride comfort of high-speed railway.

Theoretical Review on the Vertical Geometric Design Standards for High-speed Roadway (초고속 주행환경에서의 종단경사 설계기준에 관한 기초연구)

  • Song, Mintae;Kang, Hoguen;Kim, Heungrae;Lee, Euijoon;Shin, Joonsoo;Kim, Jongwon
    • International Journal of Highway Engineering
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    • v.15 no.4
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    • pp.177-186
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    • 2013
  • PURPOSES: The purpose of this study theoretically reviews vertical grade deriving process in super high speed environment and compares overseas design criteria with Domestic Standardization also draws suitable vertical grade design criteria of high standard for Domestic Circumstances in Korea. METHODS : By researching domestic vehicle registration status, calculating typical vehicle, using Vissim which is traffic simulation program, Speed-distance curve of the vehicle is derived under each design speed condition. Through Speed-distance curve, estimating critical length of grade and considering critical length of grade, maximum longitudinal incline is proposed. RESULTS : The result of domestic vehicle registration status, the typical vehicle for deriving vertical grade is calculated based on gravity horsepower ratio 200 lb/hp. For calculating critical length of grade, according to change speed of uphill entry, speed-distance curve is derived by using Vissim. Critical length of grade is calculated based on design speed 20 km/h criteria which is point of retardation. Estimated critical length of grade is 808 m and based on this result, maximum longitudinal incline was confirmed in the design speed between 130km/h to 140km/h. CONCLUSIONS: The case of the typical vehicle(truck) which is gravity horsepower ratio 200 lb/hp, maximum longitudinal incline 2% is desirable at the super high speed environment in the design speed between 130km/h to 140km/h.

Effect of Exercise with Vertical Vibration on the Balance, Walking Speed, Muscle Strength and Falls Efficacy in the Elderly (수직 진동 운동이 노인의 균형, 보행속도, 근력 및 낙상효능감에 미치는 효과)

  • Park, Jin-Hwan;Kim, Young-Min
    • Journal of the Korean Society of Physical Medicine
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    • v.15 no.4
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    • pp.131-143
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    • 2020
  • PURPOSE: The purpose of this study was to determine if an exercise program with vertical vibration can improve balance, walking speed, muscle strength and falls efficacy in the healthy elderly. METHODS: A total of 28 elderly were randomly divided into two groups: vertical vibration exercise group (exercise with vertical vibration) (N = 14) and control group (exercise without vibration) (N = 14). The exercise program, comprising calf raise, deep-squat, semi-squat, front lunge, and leg abduction was conducted with or without vibration, respectively. Subjects in each group participated in the 30 minutes training program, 2 times per week for 6 weeks. In both groups, the balance evaluation system (BT4) was used to evaluate standing balance, and walking speed was measured using the 10MWT. The manual muscle test system was applied to evaluate the knee extensor and ankle planter flexor muscle strength of the subjects, whereas the Korean falls efficacy scale (K-FES) evaluated the falls efficacy. RESULTS: After intervention, the vertical vibration group showed significantly higher changes compared to the control group, in the parameters of standing balance (P < .05), 10MWT (P < .05), left knee extensor (P < .05), right knee extensor (P < .01), both ankle plantar flexors (P < .05), and K-FES (P < .05). CONCLUSION: The exercise program with vertical vibration has the potential to improve balance, walking speed, muscle power and falls efficacy in the elderly.