• Title/Summary/Keyword: hydraulic impact pressure

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Performance Optimization of a Fully Hydraulic Breaker using Taguchi Method (Taguchi 방법을 이용한 순수 유압식 브레이커의 성능 최적화)

  • Kwak, K.S.;Chang, H.W.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.5 no.3
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    • pp.1-8
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    • 2008
  • The optimal design of a large-size fully hydraulic breaker is studied in this paper. Mathematical modeling of the breaker is established and verified by experiments. Through sensitivity analysis, the key design parameters of the breaker are selected, which mostly affect the performance of the breaker. Taguchi method is used to optimize the key design parameters in order to maximize the output power through simulation using AMESim. As a result, the impact energy is increased by 18.9% and the output power is increased by 12.4% compared with the current design. The pressure pulsation in the supply line is also reduced by the optimization.

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Evaluation of Residual Strength of CFRP Pressure Vessel After Low Velocity Impact (저속 충격 하중을 받은 탄소섬유강화 복합재 압력용기의 잔류강도 저하 평가)

  • Park, Jae-Beom;Kim, Dong-Ryun;Kim, Hyung-Geun;Hwang, Tae-Kyung
    • Composites Research
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    • v.21 no.3
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    • pp.9-17
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    • 2008
  • In this paper, the low velocity impact characteristics of filament winding CFRP pressure vessel was investigated using numerical and experimental methods. The cylinder part of CFRP vessel was impacted using triangular shape impactor which simulated the sharp edge of dropping tools and impact response behavior of CFRP was reviewed. The mechanical behavior, such as deformation and stress distribution, were also predicted by explicit finite element method and the validity of the model was investigated. For the quantitative evaluation of the residual strength of the pressure vessel after impact, a series of the ring specimens was cut from the impacted vessel and its burst pressure was measured by hydraulic pressure hoop tension test. As the results, the relationship between the residual strength degradation and the impact energy was successively obtained and a useful methodology to evaluate quantitatively the impact damage tolerance of CFRP pressure vessel was established.

Voltage Sags Impact on CAR and SOR of HANARO

  • Kim, Hyung-Kyoo;Jung, Hoan-Sung;Wu, Jong-Sup
    • Proceedings of the Korean Nuclear Society Conference
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    • 2004.10a
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    • pp.657-658
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    • 2004
  • The reactor protection system (RPS) of HANARO is a safety class system. The reactor is tripped by dropping four shut off rods (SOR). The SOR system consists of a SOR, hydraulic pump, hydraulic cylinder, solenoid valves and a power supply unit which has the AC coil contactor as a switching component. The hydraulic pump lifts up the SOR. The SOR drops by loss of the hydraulic pressure in the hydraulic circuit at the occurrence of voltage sags or interruptions. From this experiment, we knew that the magnitude of the voltage sag which impacts on this system is 70V, 500msec. The reactor regulation system (RRS) of HANARO has four CARs which are connected to the driver through a magnetic clutch. The CAR drops by loss of electromagnetic force of the magnetic clutch when the deeper voltage sags to lower than 10V, 500msec.

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An Experimental Study on Rectangular Box Sloshing (박스형 모델에 의한 슬로싱 하중에 관한 실험적 연구)

  • Jung, Dong-Woo;Chun, Soo-Sung;Park, Jun-Soo;Kwon, Sun-Hong;Jang, Taek-Soo
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2006.11a
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    • pp.386-391
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    • 2006
  • This study presents experimental results of sloshing phenomenon done on rectangular box. A simple harmonic excitation was done on the box. Two kinds of filling ratio, 20% and 30% of height, were tested. A total of 15 pressure sensors were installed to monitor the impact pressure. Each test was repeated for 20 times to ensure the repeatability. The high speed camera captured the flaw filed and the corresponding pressure were synchronize with video signal so that the video image can help the interpretation of the impact pressure. The two filling ratio made difference in the flaw characteristic and impact pressure. The use of high speed camera made it possible to understand the bubble generation mechanism. The pressure time histories were presented.

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Effect of variation of water retention characteristics due to leachate circulation in municipal solid waste on landfill stability

  • M. Sina Mousavi;Yuan Feng;Jongwan Eun;Boo Hyun Nam
    • Geomechanics and Engineering
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    • v.33 no.2
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    • pp.141-154
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    • 2023
  • This study investigated the effect of water retention characteristics between aged and fresh Municipal Solid Waste (MSW) on the stability of the landfill. A series of transient numerical modeling for the slope of an MSW landfill was performed considering the variation of water retention characteristics due to leachate circulation. Four different scenarios were considered in this analysis depending on how to obtain hydraulic conductivity and the aging degree of materials. Unsaturated hydraulic properties of the MSW used for the modeling were evaluated through modified hanging column tests. Different water retention properties and various landfill conditions, such as subgrade stiffness, leachate injection frequency, and gas and leachate collection system, were considered to investigate the pore water distribution and slope stability. The stability analyses related to the factor of safety showed that unsaturated properties under those varied conditions significantly impacted the slope stability, where the factor of safety decreased, ranging between 9.4 and 22%. The aged materials resulted in a higher factor of safety than fresh materials; however, after 1000 days, the factor of safety decreased by around 10.6% due to pore pressure buildup. The analysis results indicated that using fresh materials yielded higher factor of safety values. The landfill subgrade was found to have a significant impact on the factor of safety, which resulted in an average of 34% lower factor of safety in soft subgrades. The results also revealed that a failed leachate collection system (e.g., clogging) could result in landfill failure (factor of safety < 1) after around 298 days, while the leachate recirculation frequency has no critical impact on stability. In addition, the accumulation of gas pressure within the waste body resulted in factor of safety reductions as high as 24%. It is essential to consider factors related to the unsaturated hydraulic properties in designing a landfill to prevent landfill instability.

Performance Optimization of a Gas-Assisted Hydraulic Breaker with Dual Stroke (가스보조식 이중행정 유압브레이커의 성능 최적화)

  • Ryoo, Taek-Jik;Chang, Hyo-Whan
    • Transactions of The Korea Fluid Power Systems Society
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    • v.7 no.1
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    • pp.11-19
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    • 2010
  • A gas-assisted hydraulic breaker uses both hydraulic and pneumatic energies and the appropriate balance between them mostly effects its performance. Mathematical modeling of the breaker is established and verified by experiment. Through sensitivity analysis using AMESim, the key design parameters are selected, which mostly affect the performance of the breaker. Taguchi method is used to optimize the key design parameters to maximize the output power for long and short strokes through simulation. As the result, the output power as well as the impact energy are increased significantly compared with the existing design. The pressure pulsation in the supply line is reduced to a tolerable level and the dynamic characteristics of the piston displacement is also improved by the optimization.

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Profile Analysis on Signal Measured Local Ice Load during Icebreaking in Arctic Sea (북극해에서의 쇄빙시 국부 빙하중 계측 신호에 대한 파형 분석)

  • Jeon, Young-Ju;Rim, Chae-Whan;Lee, Tak-Kee
    • Journal of Navigation and Port Research
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    • v.37 no.2
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    • pp.143-148
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    • 2013
  • The aim of this study is to investigate the characteristics on the profile of local ice load acting on side shell of port side in bow part due to broken ice during icebreaking of ships in ice covered waters. The first Korean icebreaking research vessel 'ARAON' had a sea ice field trial in the Arctic Sea during early August, 2010, and the signals due to local ice impact measured from several strain gauges installed at bow part were gathered. It is known that these data with structural response characteristics due to local ice impact have some different characteristics with a typical hydraulic impact pressure - time history. In this study, the time history on the measured signals was analyzed and the characteristic values were presented using non-dimensional parameters.

An Experimental Study on Compressibility Effect in Sloshing Phenomenon (압축성이 슬로싱 현상에 미치는 영향에 관한 실험적 연구)

  • Park, Jun-Soo;Kim, Hyun-Yi;Lee, Ki-Hyun;Kwon, Sun-Hong;Jeon, Soo-Sung;Jung, Byoung-Hoon
    • Journal of Ocean Engineering and Technology
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    • v.23 no.4
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    • pp.12-18
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    • 2009
  • The present study focused on the compressibility of partially filled fluids in a sloshing tank. Filling ratios ranging from 18% to 26% were used to find compressible impact on a vertical wall. The model test was for 1/25 scale of a 138 K LNGC cargo tank. To investigate the two dimensional phenomenon of sloshing, a longitudinal slice model was tested. A high speed camera was used to capture the flow field, as well as the air pocket deformation. The pressure time history synchronized with the video images revealed the entire compressible process. Three typical impact phenomena were observed: hydraulic jump, flip through, and plunging breaker. In particular, the pressure time history and flow pattern details for flip through and plunging breaker are presented.

Impact assessment for water pressure and turbidity occurrence by changes in water flow rate of large consumer at water distribution networks (상수도관망에서 대수용가의 유량변화에 따른 수압 및 탁도발생 영향평가)

  • Choi, Doo Yong;Kim, Ju-Hwan;Choi, Min-Ah;Kim, Do-Hwan
    • Journal of Korean Society of Water and Wastewater
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    • v.28 no.3
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    • pp.277-286
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    • 2014
  • Water discolouration and increased turbidity in the local water service distribution network occurred from hydraulic incidents such as drastic changes of flow and pressure at large consumer. Hydraulic incidents impose extra shear stresses on sediment layers in the network, leading to particle resuspension. Therefore, real time measuring instruments were installed for monitoring the variation of water flow, pressure, turbidity and particulates on a hydrant in front of the inlet point of large apartment complex. In this study, it is attempted to establish a more stable water supply plan and to reduce complaints from customers about water quality in a district metering area. To reduce red or black water, the water flow monitoring and control systems are desperately needed in the point of the larger consumers.

Simulation of Water Hammer Mitigation at Seobyun Pumping Station (서변 가압장에서 수격현상 완화에 대한 연구)

  • Kim, Sang Hyun;Park, Nam Sik;Jung, Bong Seog;Lee, Dong Hyun
    • Journal of Korean Society of Water and Wastewater
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    • v.13 no.2
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    • pp.95-104
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    • 1999
  • A simulation of water hammer, introduced by abruptly varied motion of a pumping machine, was performed at a one of typical pumping station in Korea. Impact of hydraulic structure such as check valve, pressure relief valve and air valve in mitigating water hammer effect was estimated gradually. Method of characteristic was employed for the effective calculation of discharge and head. The relationship between various hydraulic structures and flow was properly integrated on the base of the method of characteristic. The methodology in this approach can provide significant contribution in decision making procedure for the design of hydraulic structure at a typical pumping station in Korea.

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