• Title/Summary/Keyword: Burger 모델

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Creep Behavior of Unconsolidated Rock with Mathematical Concept Solution (수학적 개념 해를 적용한 미고결 암석의 Creep거동 해석)

  • Jang, Myoung-Hwan
    • Tunnel and Underground Space
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    • v.28 no.1
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    • pp.25-37
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    • 2018
  • Burger's model was used to analyze creep characteristics of unconsolidated rock. Burger's model should determine four physical parameters from two pairs of data. In this study, physical parameters of Burger's model were determined by applying mathematical concept solution. Creep was accelerated for three years using the determined physical parameters of the Burger's model for unconsolidated rocks. As a result, the creep behavior showed a continuous deformation behavior without convergence. Therefore, in this mine, it is analyzed that the application of U-Beam is more appropriate than roofbolt in terms of stability.

Creep Characteristics of Mudstone According to Stress Level and Water Content (응력수준 및 함수비에 따른 이암의 Creep 특성에 관한 연구)

  • Lee, Younghuy;Jeong, Ghangbok
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.3
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    • pp.39-51
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    • 2012
  • The time-dependent characteristics of mudstone in this study were analyzed by performing creep tests for the mudstone in Pohang. The creep tests were conducted on various boundary conditions to observe the time-dependent behavior of mudstone and the results were compared with values predicted by established visco-elastic model and empirical equations. As a result of analysis for empirical equations proposed by Griggs(1936), Cottrell(1952) and Singh(1975), the creep constants generally tend to increase as increasing the stress level and water content. Moreover, the values predicted by Singh's equation were well fitted for the test results. Therefore, it is expected to be reasonable that creep behavior of mudstone is analyzed using Singh's equation. As a result of analysis for a Burger's model, the predicted values were well fitted for the test results. Therefore, it is expected be reasonable that the creep behavior of mudstone by a rheological model is analyzed using Burger's model.

Linearized Rheological Models of Fruits (과실(果實)의 리올러지 선형화(線型化) 모델(模型))

  • Park, J.M.;Kim, M.S.
    • Journal of Biosystems Engineering
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    • v.19 no.2
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    • pp.138-147
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    • 1994
  • The stress relaxation and creep characteristics of fruits have usually been fit to an exponential expression based on a generalized Maxwell model and Burger's model. It is known that two to three terms in the expansion of those models are necessary to obtain a satisfactory fit to the rheological characteristics of fruits. Since four to six constants appear in the models, it is very difficult to determine their physical meaning according to the experimental conditions and levels. Therefore in order to ease the comparison of data, this study was conducted to develop the linearized rheological model of the fruit from the previous studies of stress relaxation and creep characteristics of fruits. Stress relaxation and creep characteristics were able to normalize and presented in the linear form of $t/S(t)=K_1+k_2t$ and $t/C(t)={K_1}^{\prime}+{K_2}^{\prime}t$, respectively. It was possible to compare the effects of experimental conditions and levels much easier from the linearized models developed in this study than from the generalized Maxwell model and Burger's model.

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A numerical investigation on the oblique shock wave/vortex interaction (경사충격파와 와류간의 상호작용에 관한 수치적 연구)

  • Moon, Seong-Mok;Kim, Chong-Am;Rho, Oh-Hyun;Hong, Seung-Kyu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.8
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    • pp.20-28
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    • 2004
  • For the prediction on the onset of oblique shock wave-induced vortex breakdown, computational studies on the Oblique Shock wave/Vortex Interaction (OSVI) are conducted and compared with both experimental results and analytic mode1. A Shock-stable numerical scheme, the Roe scheme with Mach number-based function (RoeM), and a two-equation eddy viscosity-transport approach arc used for three-dimensional turbulent flow computations. The computational configuration is identical to available experiment, and we attempt to ascertain the effect of parameters such as a vortex strength, streamwise velocity deficit, and shock strength at a freestream Mach number of 2.49. Numerical simulations using the k-w SST turbulence model and suitably modeled vortex profiles are able to accurately reproduce many fine features through a direct comparison with experimental observations. The present computational approach to determine the criterion on the onset of oblique shock wave-induced vortex breakdown is found to be in good agreement with both the experimental result and the analytic prediction.

Characteristics of Creep Deformation Behavior of Granite under Uniaxial Compression (단축압축하중을 받는 대전 화강암의 크립 변형거동 특성에 관한 연구)

  • 홍지수;전석원
    • Tunnel and Underground Space
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    • v.14 no.1
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    • pp.69-77
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    • 2004
  • Investigation of the time-dependent behavior of rock and the associated mechanisms are of key interest in long-term stability analysis of many engineering applications. In this study, creep tests were performed on Daejeon granite samples of 25.4mm diameter under uniaxial compression at varying stress levels. The effect of moisture was investigated by testing both air-dried and fully water-saturated samples. The creep behavior of Daejeon granite exhibited three distinctive stages of primary, secondary and tertiary creep. The ultimate strength of granite under a constant stress decreased considerably with time. Saturation and immersion of the test specimen in water markedly increased the total creep strain as well as the secondary creep rate. The experimental creep curves are fitted to Burger's model as well as two other empirical models suggested by previous researchers. A number of the parameters determined for each model are dependent on stress and influenced by the presence of water. Based on the experimental results, an empirical relation between the applied stress and the time-dependent strain is established separately for each air-dried and fully water-saturated Daejeon granite.

Studies on the Rheological Property of Korean Noodles -II. Mechanical Model Parameters of Cooked and Stored Noodles- (한국 재래식 국수류의 유체 변형성에 관한 연구 -제 2 보 : 삶음시간과 저장기간에 따른 기계적 모델 상수들의 변화-)

  • Lee, Cherl-Ho;Kim, Cheol-Won
    • Korean Journal of Food Science and Technology
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    • v.15 no.3
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    • pp.295-301
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    • 1983
  • The mechanical models representing the theological property of traditional Korean noodles; i.e. wheat flour noodle and wheat-sweet potato starch noddle, were investigated from the data obtained by creep and creep recovery test using a tensile tester. The rheological behavior of the noodle products could be expressed by the 6-elements Voigt model. The instantaneous elasticity, retarded elasticity, retardation time, retarded viscosity and Newtonian viscosity of the noodle products were evaluated. With the increasing cooking time, 4-elements Burger's model was applicable to represent the mechanical behavior of wheat-sweet potato starch noodle.

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Determination of Shear Wave Velocity Profile Model Considering Uncertainty Caused by Spatial Variation of Material Property in Rockfill Zone of Fill Dam (물성치 변동성에 의한 불확실성이 고려된 국내 필댐 사력부를 위한 전단파 속도 주상도 모델)

  • Park, Hyung-Choon
    • Journal of the Korean Geotechnical Society
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    • v.35 no.2
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    • pp.29-36
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    • 2019
  • There always exist the spatial variations of material properties such as a shear wave velocity in a dam and between same type dams. These uncertainties cause those in evaluation of a shear wave velocity profile of a dam and should be considered in determining the shear wave velocity profile for a rockfill zone of a fill dam. In this paper, these uncertainties of a shear wave velocity in the rockfill zone of the fill dam in Korea are evaluated. And the shear wave velocity profile model considering these uncertainties in rockfillzone is proposed using the method based on Harmonic wavelet transform. The proposed shear wave velocity profile model is compared with Sawada-Takahashi model widely used for evaluation of a shear wave velocity profile of a rockfill zone of fill dams.

Creep behaviour of mudstone in the tertiary Duho Formation at Pohang basin (포항분지 제3기 두호층 이암의 크리프 거동)

  • 김광식;김교원
    • The Journal of Engineering Geology
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    • v.13 no.2
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    • pp.227-238
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    • 2003
  • Understanding of a creep behavior in rocks under a constant load, due to visco-elastic properties of rock, is an essential element to predict a long term ground deformation. In order to clarify the creep characteristics of the mudstone in Duho formation at Pohang basin, deposited during Tertiary, a series of laboratory tests including physical properties, unconfined compressive strength and uniaxial creep tests, was performed. The mudstone showed a higher creep potential due to 26% of clay minerals such as illite and chlorite. The unconfined compressive strength of the rock was $462{\;}kg/\textrm{cm}^2$ in average, and four creep tests were performed under constant stress of 40 to 70 % of the strength. The creep constants in the empirical and theoretical equations were deduced from the time-strain curves obtained from the tests. Among the several equations, the empirical equation proposed by Griggs and theoretical equation of Burger’s model are appreciated as the best one to express the creep behavior of the mudstone. Instantaneous elastic strain was linearly increased with stress level but strain velocity during the first creep is decreased with a similar pattern by time lapse regardless the stress level.

Effects of the Addition of Starch, Salt and Soda Ash on the Mechanical Property of Naengmyon (전분, 식염 및 알카리 첨가제가 냉면의 기계적 성질에 미치는 영향)

  • Kwon, O-Hun;Lee, Cherl-Ho
    • Korean Journal of Food Science and Technology
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    • v.16 no.2
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    • pp.175-178
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    • 1984
  • The effects of the addition of starch, salt and soda ash to the dough for Naengmyon (wheat-sweet potato starch) on the mechanical property of Naengmyon noodle were evaluated by using creep test. The strain measurement was made by taking photograph with VTR system. The creep curve of noodle strand could be fitted to the 4 element Burgers model. The instantaneous elasticity and Newtonian viscosity of the noodle strand decreased by the addition of starch. The instantaneous elasticity decreased by the addition of salt up to 4%. The mechamical parameters of the noodle varied inconsistently by the addition of soda ash.

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