• Title/Summary/Keyword: Hydraulic structure

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Characteristics of a Double-Tube Structure for the Hydraulic WIM Sensor

  • Moon, Young-Soon;Son, Won-Ho;Choi, Sie-Young
    • Journal of Sensor Science and Technology
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    • v.23 no.1
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    • pp.19-23
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    • 2014
  • A new hydraulic tube structure for WIM sensor of a new generation is presented in this paper. The double-tube structure has been developed in order to improve the performance of the hydraulic load cell. The double-tube structure hydraulic element could be reduced by 46% in pressure changes according to temperature compared to a single-tube structure. In addition to the nonlinearity can be reduced by 67.19% at the same load condition. The hydraulic load cell shows an excellent linearity and measurement accuracy as the result of the static load test.

Experimental Study for Hydraulic Characteristics as the Permeable Underlayer Thickness of Rubble mound Structure (사석방파제 투수하부층 두께에 따른 사면상의 수리특성 실험연구)

  • 윤한삼;김종욱;류청로
    • Journal of Ocean Engineering and Technology
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    • v.16 no.3
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    • pp.40-45
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    • 2002
  • In this study, the effects on hydraulic characteristics are discussed as the permeable underlayer thickness of the rubble mound structure changes. A series of hydraulic experiments were performed and wave run-up, reflection and set-up were investigated. Result indicated that wave run-down was affected by the water out from the permeable underlayer during down-rush. As the thickness increased, relative wave run-up decreased.

VORTEX STRUCTURE IN THE SCOUR HOLE BY GATE OPENING OF HYDRAULIC STRUCTURE

  • Kim, Jin-Hong;Choe, Jae-Wan
    • Water Engineering Research
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    • v.1 no.1
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    • pp.83-92
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    • 2000
  • Jet flow can occur by gate opening at downstream of a hydraulic structure such as weir of drainage gate. If the stream bed is not hard or the bed protection is not sufficient, vortex erosion occurs and a resulting scour hole will be formed due to the high shear stress of the jet flow. Once the scour hole is formed, a vortex occurs in ti and this vortex causes additional erosion. If this erosion continues and reaches to the hydraulic structure, it can undermine the bottom of the hydraulic structure and this will lead to failure of the structure itself. Thus, it is necessary to define the physical features of the vortex structure in the scour hole for the design of the bed protection. This study presents the turbulent vortex structure in the scour hole by the gate opening of the hydraulic structure. Characteristics of vortex motion, circulation, vortex scale and vortex were analyzed through experiments. Experimental results of the vortex velocity were compared with theoretical ones. From these, circulation and vortex scale were obtained with known values of inflow depth, inflow velocity and scale of scour hole

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Use of the Quantitatively Transformed Field Soil Structure Description of the US National Pedon Characterization Database to Improve Soil Pedotransfer Function

  • Yoon, Sung-Won;Gimenez, Daniel;Nemes, Attila;Chun, Hyen-Chung;Zhang, Yong-Seon;Sonn, Yeon-Kyu;Kang, Seong-Soo;Kim, Myung-Sook;Kim, Yoo-Hak;Ha, Sang-Keun
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.5
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    • pp.944-958
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    • 2011
  • Soil hydraulic properties such as hydraulic conductivity or water retention which are costly to measure can be indirectly generated by soil pedotransfer function (PTF) using easily obtainable soil data. The field soil structure description which is routinely recorded could also be used in PTF as an input to reduce the uncertainty. The purposes of this study were to use qualitative morphological soil structure descriptions and soil structural index into PTF and to evaluate their contribution in the prediction of soil hydraulic properties. We transformed categorical morphological descriptions of soil structure into quantitative values using categorical principal component analysis (CATPCA). This approach was tested with a large data set from the US National Pedon Characterization database with the aid of a categorical regression tree analysis. Six different PTFs were used to predict the saturated hydraulic conductivity and those results were averaged to quantify the uncertainty. Quantified morphological description was successively used in multiple linear regression approach to predict the averaged ensemble saturated conductivity. The selected stepwise regression model with only the transformed morphological variables and structural index as predictors predicted the $K_{sat}$ with $r^2$ = 0.48 (p = 0.018), indicating the feasibility of CATPCA approach. In a regression tree analysis, soil structure index and soil texture turned out to be important factors in the prediction of the hydraulic properties. Among structural descriptions size class turned out to be an important grouping parameter in the regression tree. Bulk density, clay content, W33 and structural index explained clusters selected by a two step clustering technique, implying the morphologically described soil structural features are closely related to soil physical as well as hydraulic properties. Although this study provided relatively new method which related soil structure description to soil structure index, the same approach should be tested using a datasets containing the actual measurement of hydraulic properties. More insight on the predictive power of soil structure index to estimate hydraulic properties would be achieved by considering measured the saturated hydraulic conductivity and the soil water retention.

A Study on the Effect of the Inclined Structure on the Hydraulic Behavior Index within Sedimentation basin (경사 구조물이 침전지내 수리거동 Index에 미치는 영향)

  • Lim, Seong-Ho;Hwang, Jun-Sik;Park, No-Suk;Kim, Seong-Su;Lim, Kyung-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.5
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    • pp.517-526
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    • 2009
  • This research has been conducted to investigate the characteristics of hydraulic behavior within the PAC contactor, the rectangular shape sedimentation basin without inclined tube and the other one with inclined tube those are parts of demonstration plants(capacity : $2,000m^3/d$) in Korea Institute of Water and Environment. As results of tracer tests, the flow within PAC contactor was evaluated to divided into plug flow and dead space distinctly, and characteristics of dead space was close to that of CSTR(Complete/continuous Stirred Tank Reactor). Also, considering Reynolds number, Froude number, Morill, Modal, NCSTR Inex and plug flow/mixed flow fraction, in the case of the rectangular shape sedimentation basin without inclined tube, the characteristics of flow pattern was close to CSTR. On the other hand, in the case of the basin with inclined tube, the region of CSTR decreased precisely compared with the case of no-tube. Until now we have recognized that the inclined hydraulic structure just reduces the surface loading rate within a sedimentation basin. Actually besides, the inclined structure have an important effect on the hydraulic behavior within the basin.

Modeling and Control of a Hydraulic Semiactive Vibration Absorber (유압식 반능동 진동 흡수기의 모델링과 제어)

  • 모창기
    • Journal of KSNVE
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    • v.8 no.4
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    • pp.700-705
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    • 1998
  • Recent past work has demonstrated that hydraulic semiactive vibration absorbers hold the promise of providing an ideal means of mitigating structural vibration. This paper examines a factor that must be treated when designing a hydraulic semiactive vibration absorber for application to a full scale structure; fluid compressibility. An expanded and consistent dynamic model of the flow process is first established. A simple feedback control is then tested on a single degree of freedom laboratory structure to verify the findings.

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Experimental study for Hydraulic Characteristics as the Permeable underlayer width of Rubble Mound Structure (사석방파제 투수층 두께에 따른 사면상의 수리특성에 관한 실험연구)

  • 윤한삼;남인식;김종욱;류청로
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.05a
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    • pp.160-165
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    • 2001
  • In this study, the effects on hydraulic characteristics are discussed as the permeable underlayer width of the rubble mound structure changes. A series of hydraulic experiments were performed and wave run-up, reflection and set-up were investigated. Results indicated that wave run-down was affected by the water out from the permeable underlayer during down-rush. As the width increased, relative wave run-up decreased.

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Characteristics of Vortex Structure and Its Shear Velocity in a Scour Hole

  • 김진홍
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.34 no.E
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    • pp.45-59
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    • 1992
  • At downstream part of the hydraulic structures such as spiliway or drainage gate, jet flow can occur by gate opening. If stream bed is not hard or bed protection is not sufficient, scour hole will be formed due to high shear stress of the jet flow. We call this primary scour. Once the scour hole is formed, a vortex occurs in it and this vortex causes additional scour. We call this secondary scour. The primary scour proceeds to downstream together with flow direction but the secondary one proceeds to upstream direction opposite to it. If the secondary one continues and reaches to the hydraulic structure, it can undermine the bottom of hydraulic structure and this will lead to failure of structure itself. Thus, it is necessary to know the physical features of the vortex structure in a scour hole, which is the main mechanism of the secondary scour. This study deals with the characteristics of the vortex structure and its shear stress which causes the secondary scour.

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A Study on the Position Control of an Electro-Hydraulic Servomechanism Using Variable Structure System (가변구조를 이용한 전기-유압서보계의 위치제어에 관한 연구)

  • 허준영;권기수;하석홍;조겸래;이진걸
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.2
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    • pp.213-220
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    • 1989
  • This paper describes the application of the variable structure control(VSC) concept for the position control of an electro-hydraulic servomotor system. The basic philosopy of VSC is that the structure of the feedback control is altered as the state crosses discontinuity surfaces in the state space with the result that certain desirable properties are achieved. The switching of the control function yields total(or selective) invariance to system parameter variations and disturbances, and closed loop eigen value placement in time-varing and uncertain systems. The control scheme is derived, implemented and tested in the laboratory where analog controller have been used to control the representive servosystem. The control system schematics are given and simple results are shown for illustration. And the results of variable structure system for the electro-hydraulic servomotor were compared to that of the fixed structure system when load disturbance and system parameter variation exists.

Safety Verification of Gantry Cranes using Hydraulic Cylinders (유압실린더를 사용한 갠트리 크레인의 안전성 검증)

  • Ko, Seong-Hoon;Lee, Kwang-Hee;Lee, Chul-Hee
    • Journal of Drive and Control
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    • v.16 no.2
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    • pp.8-14
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    • 2019
  • A typical gantry crane is generally used to lift and transport objects in various workplaces. Most of the supporting structures in a gantry crane are fixed on the ground while the moving hoist is running overhead along the girder. There are some disadvantages to its long installation time and high installation cost. Therefore, a hydraulic based gantry crane was studied to solve the issues of typical gantry cranes. The supporting structure of the proposed gantry crane consisted of a hydraulic cylinder and telescopic boom. The dimension of the proposed gantry crane can be decreased due to its simplified structure. The analytical and theoretical methods were used to verify the structural stability of the proposed crane. The most severe load condition was considered for the analysis, and the stress and deflection of the structure are analyzed. The simulation results were as expected from the theoretical analysis. Finally, the structural and dynamic safety of the proposed hydraulic based gantry crane was validated. The obtained results can be used as guidelines in the design process of the hydraulic based gantry crane.