• Title/Summary/Keyword: Hydraulic Behavior

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Dynamic Analysis of the Valves installed in the swash plate type of Hydraulic Driving Motor (사판식 구동 모터에 장착된 밸브의 동적거동 해석)

  • Noh, D.K.;Jang, J.S.
    • Journal of Drive and Control
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    • v.9 no.4
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    • pp.62-69
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    • 2012
  • Recently, hydraulic motor is getting the spotlight. It is resulted from rapid civil engineering public works by a lot of developing countries around the world. In this study, we divided the valves which are affixed in the hydraulic motor into some parts, implemented them through computer simulation, verified validation of each component, and analyzed behavior adding driving condition. Through the analyzed results with general driving condition, we found the reason why behavior became unstable as the motor had started spinning. Through the analyzed results with tough driving condition, we verified that the valve works well with it's production purpose.

Developing Analysis Model of Hydraulic System for Dental Chair (치과용 유니트체어 유압구동 시스템 해석모델 개발)

  • Dae Kyung Noh;Dong Won Lee;Taek June Kim;Joo Sup Jang
    • Journal of Drive and Control
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    • v.20 no.1
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    • pp.27-33
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    • 2023
  • From the perspective of dental chair manufacturers, it is important to of localizing hydraulic system in order to secure market competitiveness. This study aims to develop the analysis model of a dental chair which overseas companies secure core technologies. The study follows the steps below. First, the component parts of the solenoid valve unit of a foreign leading company are analyzed and implemented in virtual environment. Second, dynamic behavior scenario is established based on solenoid valve signal chart provided by a foreign leading company. The analysis model is verified and its performance is analyzed using dynamic behavior according to each scenario. Third, a simulation is carried out to determine whether the cylinder velocity of designed hydraulic system surpasses 1cm/s as required by the design.

A Study on the Dynamic Characteristics of AGV driving device (Auto Guide Vehicle) (AGV 구동부의 동특성 해석)

  • 허형석;서용권
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2002.03a
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    • pp.235-239
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    • 2002
  • In this study, a AGV(Auto Guide Vehicle) is presented and the dynamic characteristics of AGV driving device is investigated. The design factors of hydraulic pump and motor is an important component for it's performance characteristics. the dynamic characteristics of hydraulic pump and motor is simulated by using commercial code AMESim. Simulation results show that each behavior can be predicted with changing the various parameters.

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Behavior of Geotextile Tube by Numerical Analysis (수치해석기법을 이용한 지오텍스타일 튜브의 거동분석)

  • 신은철;오영인;조인휘
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.385-392
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    • 2003
  • Traditional forms of river and coastal structures have become very expensive to build and maintain, because of the shortage of natural rock. Geotextile tubes hydraulically or mechanically filled with dredged materials have been applied in hydraulic and coastal engineering in recent years(shore protection structure, detached breakwater, groins and jetty). Recently, new preliminary design criteria supported by model and prototype tests, and some stability analysis calculations have been studied. In this study, the numerical analysis was performed to investigate the behavior of geotextile tube with various properties of geotextile and hydraulic pumping conditions. Numerical analysis was executed to compare with the results from the large-scale field model tests, and also compared the results of 2-D plane strain analysis and 3-D FEM analysis. A geotextile tube was modeled using the commercial finite element analysis program ABAQUS and the one-quarter of tube was modeled. Behavior of geotextile tube during the hydraulic pumping procedure was analyzed by comparing the large-scale field model test and numerical analysis. The shape variation and maximum tube height between the numerical analysis results and large-scale filed test results are turned out to be a good agreement.

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Modeling the wetting deformation behavior of rockfill dams

  • Guo, Wanli;Chen, Ge;Wu, Yingli;Wang, Junjie
    • Geomechanics and Engineering
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    • v.22 no.6
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    • pp.519-528
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    • 2020
  • A mathematical wetting model is usually used to predict the deformation of core wall rockfill dams induced by the wetting effect. In this paper, a series of wetting triaxial tests on a rockfill was conducted using a large-sized triaxial apparatus, and the wetting deformation behavior of the rockfill was studied. The wetting strains were found to be related to the confining pressure and shear stress levels, and two empirical equations, which are regarded as the proposed mathematical wetting model, were proposed to express these properties. The stress and deformation of a core wall rockfill dam was studied by using finite element analysis and the proposed wetting model. On the one hand, the simulations of the wetting model can estimate well the observed wetting strains of the upstream rockfill of the dam, which demonstrated that the proposed wetting model is applicable to express the wetting deformation behavior of the rockfill specimen. On the other hand, the simulated additional deformation of the dam induced by the wetting effect is thought to be reasonable according to practical engineering experience, which indicates the potential of the model in dam engineering.

Computational Design of Bifurcation: A Case Study of Darundi Khola Hydropower Project

  • Koirala, Ravi;Chitrakar, Sailesh;Neopane, Hari Prasad;Chhetri, Balendra;Thapa, Bhola
    • International Journal of Fluid Machinery and Systems
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    • v.10 no.1
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    • pp.1-8
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    • 2017
  • Bifurcation refers to wye division of penstock to divide the flow symmetrically or unsymmetrically into two units of turbine for maintaining economical, technical and geological substrates. Particularly, water shows irrelevant behavior when there is a sudden change in flow direction, which results into the transition of the static and dynamic behavior of the flow. Hence, special care and design considerations are required both hydraulically and structurally. The transition induced losses and extra stresses are major features to be examined. The research on design and analysis of bifurcation is one of the oldest topics related to R&D of hydro-mechanical components for hydropower plants. As far as the earlier approaches are concerned, the hydraulic designs were performed based on graphical data sheet, head loss considerations and the mechanical analysis through simplified beam approach. In this paper, the multi prospect approach for design of Bifurcation, incorporating the modern day's tools and technology is identified. The hydraulic design of bifurcation is a major function of dynamic characteristics of the flow, which is performed with CFD analysis for minimum losses and better hydraulic performances. Additionally, for the mechanical design, a simplified conventional design method as pre-estimation and Finite Element Method for a relevant result projections were used.

Application of Flow Network Models of SINDA/FLUIN $T^{TM}$ to a Nuclear Power Plant System Thermal Hydraulic Code

  • Chung, Ji-Bum;Park, Jong-Woon
    • Proceedings of the Korean Nuclear Society Conference
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    • 1998.05a
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    • pp.641-646
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    • 1998
  • In order to enhance the dynamic and interactive simulation capability of a system thermal hydraulic code for nuclear power plant, applicability of flow network models in SINDA/FLUIN $T^{™}$ has been tested by modeling feedwater system and coupling to DSNP which is one of a system thermal hydraulic simulation code for a pressurized heavy water reactor. The feedwater system is selected since it is one of the most important balance of plant systems with a potential to greatly affect the behavior of nuclear steam supply system. The flow network model of this feedwater system consists of condenser, condensate pumps, low and high pressure heaters, deaerator, feedwater pumps, and control valves. This complicated flow network is modeled and coupled to DSNP and it is tested for several normal and abnormal transient conditions such turbine load maneuvering, turbine trip, and loss of class IV power. The results show reasonable behavior of the coupled code and also gives a good dynamic and interactive simulation capabilities for the several mild transient conditions. It has been found that coupling system thermal hydraulic code with a flow network code is a proper way of upgrading simulation capability of DSNP to mature nuclear plant analyzer (NPA).

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Code development and preliminary validation for lead-cooled fast reactor thermal-hydraulic transient behavior

  • Chenglong Wang;Chen Wang;Wenxi Tian;Guanghui Su;Suizheng Qiu
    • Nuclear Engineering and Technology
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    • v.56 no.6
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    • pp.2332-2342
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    • 2024
  • Lead-cooled fast reactors (LFRs) have a wide range of application scenarios, which require the thermal-hydraulic characteristics of LFRs to be reliable. In the present paper, the Lead-cooled fast reactor Thermal-Hydraulic Analysis Code LETHAC was developed, including the models of pipe, heat exchanger, and pool. To verify the correctness of LETHAC, two experimental facilities and three experimental cases were selected, including GFT and PLOFA tests for NACIE-UP and Test-1 for CIRCE. The calculated results show the same and consistent trend with the experimental data, but there are some discrepancies. It can be found that LETHAC is suitable and reliable in predicting the transient behavior of lead-cooled system.

Improving HSPF Model's Hydraulic Accuracy with FTABLES Based on Surveyed Cross Sections (실측 하천 단면자료를 이용한 HSPF 유역모델의 수리정확도 개선)

  • Shin, Chang Min
    • Journal of Korean Society on Water Environment
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    • v.32 no.6
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    • pp.582-588
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    • 2016
  • The hydrological simulation program FORTRAN (HSPF) is a comprehensive watershed model that employs the hydraulic function table (FTABLE) (depth-area-volume-flow relationship) to represent the geometric and hydraulic properties of water bodies. The hydraulic representation of the HSPF model mainly depends on the accuracy of the FTABLES. These hydraulic representations determine the response time of water quality state variables and also control the scour, deposition, and transport of sediments in the water body. In general, FTABLES are automatically generated based on reach information such as mean depth, mean width, length, and slope along with a set of standard assumptions about the geometry and hydraulics of the channel, so these FTABLES are unable to accurately describe the geometry and hydraulic behavior of rivers and reservoirs. In order to compensate the weakness of HSPF for hydraulic modeling, we generated alternate method to improve the accuracy of FTABLES for rivers, using the surveyed cross sections and rating curves. The alternative method is based on the hydraulics simulated by HEC-RAS using the surveyed cross sections and rating curves, and it could significantly improve the accuracy of FTABLES. Although the alternate FTABLE greatly improved the hydraulic accuracy of the HSPF model, it had little effect on the hydrological simulation.

Factors affecting hydraulic anisotropy of soil

  • Nurly Gofar;Alfrendo Satyanaga;Gerarldo D. Aventian;Gulnur Pernebekova;Zhanat Argimbayeva;Sung-Woo Moon;Jong Kim
    • Geomechanics and Engineering
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    • v.36 no.4
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    • pp.343-353
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    • 2024
  • The hydraulic anisotropic behavior of unsaturated soil has not been fully explored in relation to the grain-size distribution. The present study conducted laboratory assessments to examine the hydraulic anisotropy condition of statically compacted specimens in various initial states. The investigation incorporated the concept of hydraulic anisotropy by employing two discrete forms of soil stratification: horizontal-layering (HL) and vertical-layering (VL). The examined soils comprised sandy silt and silty sand, exhibiting either unimodal or bimodal soil-water characteristic curve (SWCC). This study aimed to investigate the potential correlation between the hydraulic anisotropy ratio and soil properties. The present study established a correlation between the hydraulic anisotropy ratio and several soil parameters, including fine content, dry density, plastic limit, and liquid limit. The study results indicate a non-linear relationship between the percentage of fine and dry density in soils with unimodal and bimodal soil-water characteristic curve (SWCC) and hydraulic anisotropy ratio.