• Title/Summary/Keyword: Bed Elevation

Search Result 104, Processing Time 0.023 seconds

The Effect of a Bed-Backrest Elevation System Combined With Hip and Knee Flexion on Lower Extremity Body-Pressure Reduction

  • Kim, Min-Hee;Yoo, Won-Gyu;Yi, Chung-Hwi;Kim, Han-Sung;Kim, Su-Jin
    • Physical Therapy Korea
    • /
    • v.15 no.4
    • /
    • pp.59-63
    • /
    • 2008
  • Pressure sores are painful and needless complications of critical illness. and manifest as a localized area of ischemic necrosis of tissue caused by pressure. This study analyzed the bed-backrest elevation system combined with hip and knee flexion for lower extremity lower pressure reduction. Eight healthy adults aged 21 to 26 years were recruited. The Body Pressure Measurement Mat of the TekScan system was used to measure the location and magnitude of the peak pressures on the body bed interface. The SPSS statistical package was used to analyze the significance of differences between the general bed-backrest elevation system and the bed-backrest elevation system combined with hip and knee flexion using the paired t-test. The result showed that the body-pressure of the lower extremity was more significantly reduced for the bed-backrest elevation system combined with hip and knee flexion ($26.6{\pm}4.3$ mmHg) than a general bed-backrest elevation system ($37.3{\pm}5.2$ mmHg) (p<.05).

  • PDF

An Analysis of Long-Term Bed Elevation Changes to Estimate Total Scour Depth at Bridge Site (교량에서의 총세굴깊이 산정을 위한 장기하상변동분석)

  • Lee, Jae-Su
    • Journal of Korea Water Resources Association
    • /
    • v.30 no.6
    • /
    • pp.721-729
    • /
    • 1997
  • Total scour depth at a bridge is comprised of three components: long-term changes, contraction scour and local scour. Therefore, the analysis of long-term bed elevation changes is very important in the estimation of total scour depth at bridge sites. In this research, long-term bed elevation changes at the Namhan River Bridge are analysed using CHARIMA and HEC-6 models. The results show that, for 5-year steady normal stream flow, the bed elevation is aggreded by 45cm for CHARIMA model but degraded by 5cm for HEC-6 model. For 5-year unsteady flow, the bed elevation is changed greatly and it has a great influence on the estimation of total scour depth. Therefore, to make a proper estimation of total scour depth, not only contraction scour and local scour, but also long-term bed elevation changes should be estimated precisely.

  • PDF

PROPAGATION OF SURFACE WAVES ON IRREGULAR BED TOPOGRAPHY

  • WARKE A. S.;DAS S. K.;DEBNATH L.
    • Journal of applied mathematics & informatics
    • /
    • v.20 no.1_2
    • /
    • pp.197-208
    • /
    • 2006
  • This paper deals with the exact solution of surface gravity waves in an ocean with irregular bed topography. In order to obtain water surface elevation and run-up of infra-gravity waves when the bed is either wavy or exponential, closed form solutions are obtained. Numerical computations indicate that when solitary wave or sinusoidal wave conditions are applied at the boundary, water surface elevation attains near Gaussian profile.

FINITE ELEMENT MODELING FOR HYDRODYNAMIC AND SEDIMENT TRANSPORT ANALYSIS (II) : SEDIMENT TRANSPORT STUDY

  • Noh, Joon-Woon
    • Water Engineering Research
    • /
    • v.4 no.2
    • /
    • pp.99-109
    • /
    • 2003
  • Since bed elevation changes are mainly dependent on the flow velocity and corresponding shear stress, it is possible to predict bed elevation numerically using velocity components. For the scour analysis due to channel contraction, a bed load transport model is developed and applied to estimate scour depth around coffer dam in the Mississippi River. During Phase I of the Lock & Dam No. 26 replacement project, a coffer dam was constructed to reduce the flow area approximately by 50%. Flow velocity increases due to the flow area reduction yields significant lowering (erosion) of the channel bed elevation. The proposed numerical model solves the sediment continuity equation using the finite element method to evaluate scour process in the vicinity of the coffer dam

  • PDF

Bed Changes downstream the Singok Submerged Weir in the Han River Estuary - from 2009 to 2010 (한강 하구 신곡수중보 하류에서 하상변동 - 2009년부터 2010년까지)

  • Hwang, Seung-Yong;Lee, Samhee
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.38 no.6
    • /
    • pp.819-829
    • /
    • 2018
  • The bed change survey was carried out and its tendency was analyzed at the downstream of the Singok Submerged Weir in the Han River Estuary (HRE). In order to focus on the bed change in the low flow channel, we calculated the mean bed elevation based on the bankfull discharge. Thanks to the amount of bed changes calculated by using the 'averaged bed', we could compare the riverbeds of various periods with consistent criteria. In the HRE, revealed was the bed change cycle between degradation by flood and aggradation by tide at the non-flood season.

Sensitivity Analysis of Bed Changes for Different Sediment Transport Formulas Using the HEC-6 Model - The Lower Nakdong River (HEC-6 모형을 이용한 유사량 공식에 따른 하상변동 민감도 분석 - 낙동강 하류를 대상으로)

  • Jeong, Won-Jun;Ji, Un;Yeo, Woon-Kwang
    • Journal of Environmental Science International
    • /
    • v.19 no.10
    • /
    • pp.1219-1227
    • /
    • 2010
  • In this study, the sensitivity analysis of bed changes due to the various sediment transport equations have been conducted for 80 km reach of the Lower Nakdong River using the HEC-6 which is one dimensional numerical model. The bed elevation changes according to the different sediment transport formulas were compared and analyzed quantitatively. As a result of the numerical simulation, the final bed elevation calculated by Engelund and Hansen(1967), Ackers and White(1973), and Yang(1979) formulas was similar to one another in configuration. The bed change simulated by Engelund and Hansen(1967) were greatest among them, for example, 5.5 m deposition and 2.9 m erosion for 100 years. Also, in the case of Toffaleti (1969) equation, the maximum bed deposition of 8.04 m after 100 years was induced at the 73 km location upstream of the Nakdong River Estuary Barrage. Meyer-Peter-M$\ddot{u}$ller(1948) and Wilcock(2001) formulas produced the deposition only at the upstream end and there was little bed change in the downstream area. The unreal bed configuration of continuously up and down pattern was simulated by Laursen(1958) transport equation.

Prediction and Historical Analysis of Long-term Bed Elevation Change in the Mankyung-gang River (만경강의 장기하상변동 예측 및 이력분석)

  • Kim, Seung Ki;Kim, Ji Sung;Kim, Kyu Ho;Choi, Sung-Uk
    • Ecology and Resilient Infrastructure
    • /
    • v.5 no.1
    • /
    • pp.25-34
    • /
    • 2018
  • This study presents prediction and historical analysis of the long-term bed elevation change in the Mankyung-gang River. The study area is a 25 km long reach including middle and lower courses of the Mankyung-gang River. HEC-RAS program was used for numerical predictions, and values of roughness coefficients were calibrated. Then, predictions were made in the two periods, seven years from 1986 to 1993 and twelve years from 1993 to 2005. Simulation results were compared with two sets of measured data for bed elevations. Four sediment transport formulas, namely MPM's, Toffaleti's, MPM-Toffaleti's, and Yang's formula, were tested. Simulation results showed that none of the four sediment transport formulas predicted the bed elevation change in the period of 1986 - 1993. This is related to the fact that dredging work was performed in the upstream reach in the period of 1986 - 1993, and sediment was deposited in this part severely later. However, it was found that MPM-Toffaleti's formula predicted properly the bed elevation change for the period of 1993 - 2005.

2D Finite Element Modeling of Bed Elevation Change in a Curved Channel (유한요소법을 이용한 만곡수로에서의 2차원 하상변동 수치모형)

  • Kim Tae Beom;Choi Sung-Uk;Min Kyung Duck
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2005.05b
    • /
    • pp.414-418
    • /
    • 2005
  • A finite element model is developed for the numerical simulation of bed elevation change in a curved channel. The SU/PG (Streamline-Upwind/Petrov-Galerkin) method is used to solve 2D shallow water equations and the BG (Bubnov-Galerkin) method is used for the Exner equation. For the time derivative terms, the Crank-Nicolson scheme is used. The developed model is a decoupled model in a sense that the bed elevation does not change simultaneously with the flow during the computational time step. The total load formula with is used for the sediment transport model. The slip conditions are described along the lateral boundaries. The effects of gravity force due to geometry change and the secondary flows in a curved channel are considered in the model. For the verification, the model is applied to two laboratory experiments. The first is $140^{\circ}$ bended channel data at Delft Hydraulics Laboratory and the second is $140^{\circ}$ bended channel data at Laboratory of Fluid Mechanics of the Delft University of Technology. The finite element grid is constructed with linear quadrilateral elements. It is found that the computed results are in good agreement with measured data, showing a point bar at the inner bank and a pool at the outer bank.

  • PDF

River Terraces and Geomorphic Development of Subi Basin, Yeongyang (하안단구와 수비분지의 지형발달)

  • Son, Myoung Won
    • Journal of The Geomorphological Association of Korea
    • /
    • v.24 no.2
    • /
    • pp.15-25
    • /
    • 2017
  • Subi basin is located at the crestline of Taebaek mountains. This paper aims to elucidate the geomorphic development of Subi basin through the analysis of river terraces built in Wangpi-cheon and Banbyeon-cheon. Wangpi-cheon flows northeastward from Subi basin, and Banbyeon-cheon flows southward at the west of Subi basin. Absolute age of terrace is measured by means of OSL methodology, long profile of Wangpi-cheon is made up with 10m interval contour line, and the elevation above river bed of high terraces is measured at the end part of terrace. The results are as follow: Firstly, high river terraces of Subi basin, Wangpi-cheon and Banbyeon-cheon are formed about 40 kyr(MIS 3) being interstadial stage of last glacial period. Secondly, the elevation above river bed of high terraces of Wangpi-cheon and Banbyeon-cheon tends to increase toward upstream. It means that the uplift of Taebaek Mountains influences considerably the formation of their terraces. Thirdly, the elevation above river bed of high terraces at the reach from Seomchon to Suha-ri of Wangpi-cheon tends to decrease toward upstream. This section is captured from Banbyeon-cheon flowing in the opposite direction. River piracy has occurred from the time of formation of Suha-ri high terrace to the time of formation of Hantee wind gap. Finally, for fluvial system of Wangpi-cheon to establish dynamic equilibrium, topographic axis will move toward Banbyeon-cheon.