• Title/Summary/Keyword: Centrifugal model test

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Development of Horizontal Displacement Sensor for Rainfall-simulated Centrifugal Model Test (강우재현 원심모형실험에 적용하기 위한 수평변위 계측장치의 개발)

  • Lee, Chungwon;Park, Sungyong;Kim, Yongseong
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.12
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    • pp.71-77
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    • 2014
  • Heavy rainfall induces many disasters including slope failure and infrastructure collapse. In this point of view, rainfall-simulated centrifugal model test can be a reasonable tool to evaluate the stability of geotechnical structure. In order to obtain the displacements of a model in centrifugal model test, in general, LVDT and laser displacement sensor are used. However, when the rainfall is simulated, the LVDT has the problem of excessive infiltration into the model ground, and the laser displacement sensor provides the measuring result with inaccuracy due to the dispersion of the laser radiation. Hence, in this study, horizontal displacement sensor for rainfall-simulated centrifugal model test was developed. This sensor produced with a thin elastic steel plate and gave the accurate relationship between the displacement and the strain.

A Study on Pore Water Pressure Behavior of Fill Dam with Water Level Raising using Centrifugal Model Tests (원심모형실험에 의한 수위상승시 필댐의 간극수압 거동 연구)

  • Lee, Chung-Won;Chang, Dong-Su;Park, Sung-Yong;Kim, Ki-Sung;Kim, Yong-Seong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.55 no.2
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    • pp.87-95
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    • 2013
  • The aim of this study is to examine the behavior of reservoir fill dam with the water level raising by use of the centrifugal model test and the numerical simulation. In this study, LIQCA2D-SF based on the cyclic elasto-plastic constitutive model proposed by Oka et al. (1999) is applied for numerical simulation. In order to investigate the displacements and the pore water pressures in the fill dam due to the water level raising velocity, three model tests in centrifugal field of 50g for fill dams were conducted. A comparison between the test result and the simulation result has provided the influence on the displacement and the pore water pressure of the fill dam with increasing up of the water level.

Seismic Behavior of Deterioration Reservoir Embankment Using Dynamic Centrifugal Model Tests (동적원심모형실험에 의한 재개발 저수지의 동적 거동특성)

  • Park, Sung-Yong;Chang, Suk-Hyun;Lim, Hyun-Taek;Kim, Jung-Meyon;Kim, Yong-Seong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.58 no.3
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    • pp.91-100
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    • 2016
  • Recently, lots of damages have been lost because large magnitude earthquakes were occurred in the world. It has been increased the number of earthquakes in Korea. It needs improvement required for the repair of deteriorated reservoirs, reinforcement and raised reservoir coping with climate change and earthquake. This study aims to investigate the seismic behavior of deterioration reservoir levee using dynamic centrifugal model test. Therefore, two case tests in centrifugal field of 60 g, the result has provided the influence on the acceleration response, displacement, settlement and the pore water pressure of the reservoir with earthquakes. From the results larger displacement and acceleration response at the front side of reservoir embankment with poor-fabricated core in seismic condition may degrade overall stability. Reasonable reinforcement method of the raised reservoir embankment is required for ensuring long-term stability on earthquake.

Stability and Earth Pressure Distribution of Excavated Earth Retaining Wall by Centrifugal Model Tests (원심모형실험에 의한 굴착 흙막이벽의 안정 및 토압분포)

  • Kim, Y.C.;Lee, C.K.;Kim, H.J.;Ahn, K.K.;Lee, M.W.;Heo, Y.
    • Journal of the Korean Society of Safety
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    • v.12 no.3
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    • pp.139-146
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    • 1997
  • In this study, centrifugal model tests were performed to investigate the behavior of excavated earth retaining wall with the depth of excavation and different types of wall(aluminum, steel panel). Jumunjin standard sand was used for foundation soil. The raining method was adopted to form the required relative density of the model ground. The lateral earth pressure measured from tests were compared with estimated active earth pressure by Rankine's theory. The test results have shown that the earth pressure acting on the retaining wall and the rotation displacement of the wall are influenced by the depth of excavation and the type of wall. It was found from the test results that the deformation of the wall increases with the depth of excavation.

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Effects of Double Volute on Performance of A Centrifugal Pump (원심펌프의 성능에 대한 더블 볼류트의 영향)

  • Shim, Hyeon-Seok;Heo, Man-Woong;Kim, Kwang-Yong
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.1
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    • pp.37-44
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    • 2016
  • In this study, a parametric study of a centrifugal pump with double volute has been performed numerically using three-dimensional Reynolds-averaged Navier-Stokes equations. The shear stress transport model was selected as turbulence closure through turbulence model test. The finite volume method and unstructured grid system were used for the numerical analysis. The optimal grid system in the computational domain was determined through a grid dependency test. The expansion coefficient, circumferential and radial starting positions and length of divider were selected as the geometric parameters to be tested. And, the hydraulic efficiency and the radial thrust coefficient were considered as performance parameters. It was found that the radial thrust and hydrualic efficiency are more sensitive to the expansion angle and circumferential starting position of the divider than the other geometrical parameters.

Field Performance Test and Prediction of Power Consumption of a Centrifugal Chiller (현장에서 운전중인 터보냉동기의 성능 측정과 전력 소비량 예측)

  • Jang, Yeong-Su;Sin, Yeong-Gi;Kim, Yeong-Il;Baek, Yeong-Jin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.12
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    • pp.1730-1738
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    • 2001
  • This paper presents an overview of testing and analyzing field performance of a centrifugal chiller which has a rated capacity of 200 RT(703 kW). Field data of a chiller installed in the cleanroom research building of KIST has been collected far performance analysis. The operating data included start-up, shut-down, and quasi-static state where cooling capacity and compressor power consumption varied cyclically. It was found that the steady-state thermodynamic model could be applied to relate the cooling capacity and COP under quasi-static conditions. The results led to finding the required cooling load pattern and a possible energy saving method. This study provides a method of evaluating performance of a large capacity centrifugal chiller in which field test is necessary.

Numerical Simulation of Soil-Structure Interaction in Centrifuge Shaking Table System (지반-구조물 상호작용 원심모형시험에 대한 수치해석)

  • Kim, Dong-Kwan;Park, Hong-Gun;Kim, Dong-Soo;Lee, Sei-Hyun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09a
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    • pp.201-204
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    • 2010
  • Earthquake load to design a structure has been calculated from a fixed base SDOF model using amplified surface accelerations along soft soil layers. But the method dose not consider a soil-structure interaction. Centrifugal experiments that were consisted of soil, a shallow foundation and a structure were performed to find the effects of soil-structure interaction. The experiments showed that mass and stiffness of the foundation affected a response of the structure and nonlinear behavior of soil near the foundation. And a rocking displacement caused by overturning moment affected the response and increases a damping effect. In this study, the centrifugal experiment was simulated as a two dimensional finite element model. The finite element model was used for nonlinear time domain analysis of the OpenSees program. The numerical model accurately evaluated the behaviors of soil and the foundation, but the rocking effect and the behavior of structure were not described.

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Evaluation of Ground Deformation during Excavation of Vertical Shaft through Centrifuge Model Test (원심모형실험을 통한 원형 수직구 굴착 중 발생하는 지반 변형 평가)

  • Kim, Joonyoung
    • Journal of the Korean Geotechnical Society
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    • v.38 no.1
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    • pp.35-45
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    • 2022
  • When constructing a cylindrical vertical shaft through the open-cut method, the walls are generally designed to be temporary flexible walls that allow a certain level of displacement. The earth pressure applied to the flexible walls acts as an external force and its accurate estimation is essential for reasonable and economical structure design. The earth pressure applied to the flexible wall is closely interrelated to the plastic deformation of the surrounding ground. This study simulated a stepwise excavation for constructing a cylindrical vertical shaft through a centrifugal model test and evaluated the continuous deformation behaviors of the surrounding ground through digital image analysis.

Seismic Stability Evaluation of the Breakwater Using Dynamic Centrifugal Model Test (동적원심모형 시험을 이용한 지진 시 방파제의 내진안정성 검토)

  • Kim, Young-Jun;Jang, Dong-In;Kawk, Chang-Won;Park, Inn-Joon
    • Journal of the Korean Geotechnical Society
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    • v.37 no.6
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    • pp.39-50
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    • 2021
  • Recently, as the occurrence of earthquakes with a magnitude of 5.0 or higher in Korea increases, many studies and interests in seismic design are increasing. A lot of damage was caused by the Pohang earthquake in 2017, and port facilities such as a breakwater were also damaged. This study analyzed the dynamic behavior of the upright breakwater, an external facility, based on a centrifugal model experiment. A series of centrifugal model test was conducted by three different seismic waves such as Pohang Earthquake Wave, Artificial Wave I, and II. As a result, the dynamic behavior of upright breakwater was analyzed. The review showed that acceleration amplification tends to be suppressed as breakwater foundation ground increases support and stiffness through DCM reinforcement and riprap replacement.

Practical Modeling and PI Controller Design for Centrifugal Water Chillers (터보냉동기를 위한 실용적 모델링과 PI 제어기 설계)

  • Jeong, Seok-Kwon;Han, Sung-Joon;Jung, Young-Mi
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.4
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    • pp.187-194
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    • 2015
  • This paper describes the PI controller design based on a practical transfer function model for centrifugal water chillers. The rotational speed of a compressor and the opening angle of an electronic expansion valve were simultaneously regulated as manipulated variables to maintain temperature reference and to ensure high efficiency of the chiller. The COP according to the change in each variable was investigated by performing some static experiments, and it was reflected in the PI controller design to accomplish the high efficiency control. Especially, the practical transfer function model of the chiller was built based on the dynamic experimental data considering the strong inherent non-linearity and complexity of the chiller system. The validity of the designed PI controller was proven by some experimental results using the test facility and the results were also compared to the conventional evaporating pressure control results.