• Title/Summary/Keyword: displacement of center of pressure

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Effects of Eight-week Pilates Training on Elderly People's Dynamic and Static Balance Abilities

  • Choi, Jung-Hyun
    • Journal of the Korean Society of Physical Medicine
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    • v.9 no.3
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    • pp.325-331
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    • 2014
  • PURPOSE: Improving elderly people's balance ability through pilates which may be easily applied in ordinary life is considered an important intervention method for elderly people. Therefore, this study examines the effects of pilates training on elderly people's static and dynamic balance abilities and provides clinical data to improve this ability. METHODS: The pilates program was applied to 19 elderly subjects three times per week for 8 weeks. Their training level took into consideration their age and was set so that the rating scales of perceived exertion became 13 to 14. Prior to the initiation of the experiment, the subjects had an adaptation period in order to practice the order and motions of pilates. After the adaptation period, the subjects received training. The program was conducted three times per week, for eight weeks. Their dynamic balance ability was observed through the timed up and go (TUG) test and tandem walk test (TWT), and their static balance ability was evaluated by the center of pressure (COP) area, medial-lateral displacement, and anterior-posterior displacement. RESULTS: The results of the TUG test and TWT and evaluations of the COP area and medial-lateral displacement were significantly different after the pilates exercise program compared to those before the program began. CONCLUSION: The results show that an 8-week pilates exercise program is an effective method to increase elderly people's static and dynamic balance abilities. In addition, the application result of the pilates exercise program will provide useful information for future research on elderly people's balance ability.

Experimental Analysis of Corbel Part Behaviour in Inground LNG Storage Tank (지하식 저장탱크 Corbel부 실험적 거동 분석)

  • Yoon I.S.;Kim J.K.;Kim Y.K.;Kim J.H.
    • Journal of the Korean Institute of Gas
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    • v.10 no.1 s.30
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    • pp.56-60
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    • 2006
  • The connection part (corbel) between bottom slab and side wall in inground LNG storage tank has hinge conditions partly fixed by using anchor bars to reduce stress concentration. The corbel deforms in both radial and vertical directions under load conditions of the LNG tank such as LNG temperature, hydraulic pressure, etc. Membrane is an important part from the viewpoint of design because the deformation of the corbel is transformed directly to the membrane and superposed with other deformations. Behavior of the corbel has been investigated through various sensors to measure temperature, load and displacement. And the test data have been compared with finite element results analysis to propose a more reasonable design of LNG storage tank.

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A Study on the Characteristic of Contact Pressure for CPB (Cold Pad Batch) Padder Roll Controlled by Hydraulic Single Cell (단일 유압 Cell로 제어되는 CPB(Cold Pad Batch)용 패더롤의 접촉압력 특성 연구)

  • Cho, Kyung-Chul;Lee, Eun-Ha;Jo, Soon-Ok;Park, Si-Woo;Hwang, Youn-Sung;Kim, Soo-Youn
    • Textile Coloration and Finishing
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    • v.29 no.2
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    • pp.86-96
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    • 2017
  • To make uniform pressure distributed over the contact surface was necessary to cold pad batch dyeing machine. In this study, to confirm characteristic of flexibility and the contact pressure distribution through experimental analysis of padder roll were controlled by hydraulic cell. When there were no load pressure only inner pressure, the value of displacement in the center of padder were greater than the end of the padder. The results of this study showed that the padder had the optimum value of inner pressure for uniform contact pressure distribution. Measuring the contact pressure in a padder system were driven by using a pre-scale film. Uniform contact pressure distribution of cell padder were a linearly with load pressure and inner pressure. When the load pressure was less than 8 tons, the inner pressure for the uniform contact pressure was 1~4 bar. The padder roll performance curves proposed in this study were available for practical production environments and various roll designs.

A Study on the Strength Safety of the Prestressed Concrete Outer Tank for a Membrane LNG Storage Tank (멤브레인식 LNG 저장탱크용 PC 외부탱크의 강도안전성에 관한 연구)

  • Kim, Chung-Kyun;Kim, Do-Hyun
    • Journal of the Korean Institute of Gas
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    • v.13 no.1
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    • pp.21-27
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    • 2009
  • This paper presents the numerical study on the strength safety of the prestressed concrete outer tank for a LNG storage tank, which is manufactured by sets of membrane panels with special corrugations. This study for a finite element analysis assumes that the membrane panel of the inner tank was fractured and the liquefied natural gas stored in the inner membrane tank was leaked to the prestressed concrete outer tank. The stress and displacement of the outer tank have been analyzed for five different loadings, which are originated by a hydrostatic pressure and a weight of a LNG, a temperature difference, a weight of the prestressed concrete and a boil-off gas pressure. The computed FEM results indicate that the PC outer tank with a storage capacity of 200,000$m^3$ has a good strength safety for a leaked LNG from the membrane inner tank, but the increased cryogenic loadings in which are originated by a leaked LNG decreases the strength safety of the PC structure. This may lead to the collapse of the outer storage tank.

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Relationship between Dimensionless Leg Stiffness and Kinetic Variables during Gait Performance, and its Modulation with Body Weight

  • Hyun, Seung Hyun;Ryew, Che Cheong
    • Korean Journal of Applied Biomechanics
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    • v.26 no.3
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    • pp.249-255
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    • 2016
  • Objective: This purpose of this study was to analyze the relationship between dimensionless leg stiffness and kinetic variables during gait performance, and its modulation with body weight. Method: The study sample consisted of 10 young women divided into 2 groups (Control, n=5 and Obese, n=5). Four camcorders (HDR-HC7/HDV 1080i, Sony Corp, Japan) and one force plate (AMTI., USA) were used to analyze the vertical ground reaction force (GRF) variables, center of pressure (COP), low limb joint angle, position of pelvis center and leg lengths during the stance phase of the gait cycle. Results: Our results revealed that the center of mass (COM) displacement velocity along the y-axis was significantly higher in the obese group than that in control subjects. Displacement in the position of the center of the pelvis center (Z-axis) was also significantly higher in the obese group than that in control subjects. In addition, the peak vertical force (PVF) and dimensionless leg stiffness were also significantly higher in the obese group. However, when normalized to the body weight, the PVF did not show a significant between-group difference. When normalized to the leg length, the PVF and stiffness were both lower in the obese group than in control subjects. Conclusion: In the context of performance, we concluded that increased dimensionless leg stiffness during the gait cycle is associated with increased velocity of COM, PVF, and the change in leg lengths (%).

Wind-induced dynamic response and its load estimation for structural frames of circular flat roofs with long spans

  • Uematsu, Yasushi;Yamada, Motohiko
    • Wind and Structures
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    • v.5 no.1
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    • pp.49-60
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    • 2002
  • This paper describes a simple method for evaluating the design wind loads for the structural frames of circular flat roofs with long spans. The dynamic response of several roof models were numerically analyzed in the time domain as well as in the frequency domain by using wind pressure data obtained from a wind tunnel experiment. The instantaneous displacement and bending moment of the roof were computed, and the maximum load effects were evaluated. The results indicate that the wind-induced oscillation of the roof is generally dominated by the first mode and the gust effect factor approach can be applied to the evaluation of the maximum load effects. That is, the design wind load can be represented by the time-averaged wind pressure multiplied by the gust effect factor for the first mode. Based on the experimental results for the first modal force, an empirical formula for the gust effect factor is provided as a function of the geometric and structural parameters of the roof and the turbulence intensity of the approach flow. The equivalent design pressure coefficients, which reproduce the maximum load effects, are also discussed. A simplified model of the pressure coefficient distribution is presented.

Analysis and research on teeth thermodynamic coupling contact of gear transmission system

  • Wang, Xigui;Wang, Yongmei;Zhao, Xuezeng;Li, Xinglin
    • Coupled systems mechanics
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    • v.4 no.3
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    • pp.237-249
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    • 2015
  • In the gear meshing process, gear temperature field concerns the meshing surface friction, the friction heat depends on the contact pressure, the contact pressure is affected by the elastic deformation of gears and the temperature field caused by the thermal deformation, so the temperature field, stress field and displacement field should be mutual coupling. It is necessary to consider in meshing gear pair in the operation process of thermodynamic coupling contact stress (TCCS) and thermodynamic coupling deformation (TCD), and based on thermodynamic coupling analysis (TCA) of gear teeth deformation.

A Study on Integrated Control and Safety Management Systems for LNG Membrane Storage Tank (멤브레인식 LNG 저장탱크용 통합제어안전관리시스템에 대한 연구)

  • Kim, Chung-Kyun
    • Journal of the Korean Institute of Gas
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    • v.14 no.2
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    • pp.40-46
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    • 2010
  • In this study, the integrated control and safety management system for a super-large LNG membrane storage tank has been presented based on the investigation and analysis of measuring equipments and safety analysis system for a conventional LNG membrane storage tank. The integrated control and safety management system, which may increase a safety and efficiency of a super-large LNG membrane storage tank, added additional pressure gauges and new displacement/force sensors at the steel anchor between an inner tank and a prestressed concrete structure. The displacement and force sensors may provide clues of a membrane panel failure and a LNG leakage from the inner tank. The conventional leak sensor may not provide proper information on the membrane panel fracture even though LNG is leaked until the leak detector, which is placed at the insulation area behind an inner tank, send a warning signal. Thus, the new integrated control and safety management system is to collect and analyze the temperature, pressure, displacement, force and LNG density, which are related to the tank system safety and leakage control from the inner tank. The digital data are also measured from measurement systems such as displacement and force of a membrane panel safety, LNG level and density, cool-down process, leakage, and pressure controls.

A Study on the Characteristics of Carbon Dioxide Emissions from Gasoline Passenger Cars (국내 휘발유 승용차의 CO2 배출 현황)

  • Lyu, Young-Sook;Ryu, Jung-Ho;Jung, Sung-Woon;Jeon, Min-Seon;Kim, Dae-Wook;Eom, Myung-Do;Kim, Jong-Choon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.2
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    • pp.58-64
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    • 2007
  • As the concerns regarding global worming were increased, the pressure of greenhouse gas(GHG) emission reduction on mobile source was also increased. Carbon dioxides contribute over 90% of total GHG emission and the mobile source occupies about 20% of this $CO_2$ emission. Therefore automotive exhaust is suspected to be one of the major reasons of the rapid increase in greenhouse effect gases in ambient air. In this study, in order to investigate $CO_2$ emission characteristics from gasoline passenger cars(PC), which is the most dominant vehicle type in Korea, 106 vehicles were tested on the chassis dynamometer. $CO_2$ emissions and fuel efficiency were measured. The emission characteristics by displacement, gross vehicle weight, vehicle speed and CVS-75/vehicle speed mode were discussed. Test modes were vehicle speed modes and CVS-75 mode that have been used to develop emission factors and to regulate for light-duty vehicle in Korea. It was found that $CO_2$ emissions showed higher large displacement, heavy gross vehicle weight, low vehicle speed and CVS-75 mode than small displacement, light gross vehicle weight, high vehicle speed and vehicle speed mode, respectively. From these results, correlation between $CO_2$ emission and fuel efficiency was also determined. The results of this study will contribute to domestic greenhouse gas emissions calculation and making the national policy for climate change.

Design of a Smart Safety Measurement System Using Bluetooth Beacon Sensor Nodes (블루투스 비콘 센서 노드를 활용한 스마트 안전 계측 시스템 설계)

  • Park, Young-soo;Park, Chang-jin;Cho, Sun-hee;Park, Kyoung-yong;Kim, Min-sun;Seo, Jeongwook
    • Journal of Advanced Navigation Technology
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    • v.21 no.1
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    • pp.126-131
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    • 2017
  • This paper designs a smart safety measurement system with Bluetooth beacon sensor nodes that can provide risk detection and evacuation/countermeasure services. The Bluetooth beacon sensor nodes is easily able to be attached to old building wall or construction or civil structure with potential danger. The proposed smart safety measurement system transmits various sensor data such as acceleration, gyroscope, geomagnetic, pressure, altitude, temperature, humidity at the spot where Bluetooth beacon sensor nodes are installed, and we can use them for risk perception, prediction, and warning services. To verify the effectiveness of the proposed system, we performed filed tests which showed that measured displacement values of precast retaining walls were within the permitted displacement value of 38.5 mm.