• Title/Summary/Keyword: Numerical Analysis

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Error Analysis of Muskingum-Cunge Flood Routing Method (Muskingum-Cunge 홍수추적 방법의 오차해석)

  • Kim, Dae-Geun;Seo, Il-Won
    • Journal of Korea Water Resources Association
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    • v.36 no.5
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    • pp.751-760
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    • 2003
  • Error analysis of finite difference equation on the Muskingum-Cunge flood routing method with free time and space weighting factor was carried out. The error analysis shows that the numerical solution of the Muskingum-Cunge method becomes diverged with time when the sum of time weighting factor and space weighting factor is greater than 1.0. Numerical diffusion increases when the sum of time weighting factor and space weighting factor decreases. Numerical diffusion and numerical oscillation increase when the grid resolution is coarse. Numerical experiments and field applications show that the Muskingum-Cunge method with free space weighting factor is more effective for simulating the flood routing with great peak diminution than conventional Muskingum-Cunge method with fixed space weighting factor, 0.5.

2-D Consolidation Numerical Analysis of Multi_Layered Soils (II) (다층 지반의 2차원 압밀 수치해석 II)

  • 류권일;김팔규;구기욱;남상규
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.665-672
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    • 2000
  • The problems of discontinuous layer interface are very important in the algorithm and programming for the analysis of multi-layered consolidation using a numerical analysis, finite difference method(F.D,M.). Better results can be obtained by the process for discontinuous layer interface, since it can help consolidation analysis to model the actual ground Explicit method is simple for analysis algorithm and convenient for use except for applying the operator Crank-Nicolson method represents implicit method, which have different analysis method according to weighting factor. This method uses different algorithm according to dimension. And, this paper uses alternative direction implicit method. The purpose of this paper provides an efficient computer algorithm based on numerical analysis using finite difference method which account for multi-layered soils with confined aquifer to determine the degree of consolidation and excess pore pressures relative to time and positions more realistically.

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A Numerical Analysis of Hydraulic Hammer Compaction (유압식 햄머다짐의 수치해석적 연구)

  • 박인준;박양수;김수일
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.03b
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    • pp.183-190
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    • 2000
  • Effective range of Hydraulic Hammer Compaction was studied by numerical analysis instead of empirical method. Numerical analyses were carried out with commercial FEM code, ABAQUS, and verified by comparing the numerical results with field tests of Hydraulic Hammer Compaction. Most of material properties were evaluated by data from laboratory and in-situ tests. Vertical effective range was estimated by distribution curve of plastic strain energy dissipated through soil layers under dynamic load and these results were in good agreement with field tests. Based on verification, the effects of governing properties of Hydraulic Hammer Compaction such as number of hit can be determined by numerical analyses. In addition, vertical effective range can also be determined by Menard's empirical equation using the external work at converging time of plastic strain energy in numerical analysis. This implies that the minimum energy of Hydraulic Hammer Compaction for improvement can be determined by Menard's equation.

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Experimental Data Analysis using Computational Numerical Analysis on the Response of One-way Reinforced Concrete Slab under Blast Loading (전산수치해석을 이용한 일방향 철근콘크리트 부재의 폭발 실험결과 분석)

  • Ji, Hun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.19 no.4
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    • pp.424-434
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    • 2016
  • A few blast experiments are conducted to investigate the behavior of one-way reinforced concrete(RC) slabs under blast loading. Reflected blast characteristics as well as displacements and damage patterns of RC slabs are measured. Numerical models are also established in the software ANSYS AUTODYN to reproduce the experiments on RC slabs. The numerical models are distinguished from each other by different boundary conditions at the edges of RC slabs, which are assumed to reproduce displacements and damage patterns resulted from the experiments. The boundary condition of the experimental tests is estimated from the numerical simulation results. From the numerical simulation results, the boundary condition should be improved in order to measure the accurate maximum displacement in the experimental tests.

Numerical Simulation of Rehabilitated Flexural RC Member using High Performance Composite (균열제어 기능성 복합재료를 이용한 RC 휨 부재 보강수치해석)

  • 신승교;김태균;임윤묵
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.543-548
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    • 2003
  • In this study, a numerical model is developed using axial deformation link elements that can effectively predict the failure behavior of RC type structures. Using this mod 1, numerical analysis was performed to investigate the strengthening effect and failure behavior of structures repaired with a new material. High-Performance Cementitious Composites, which is characterized by its ductility with 5% strain-capacity is used as a repair material. To investigate the validity of developed numerical model, simulations of direct tension specimen and flexural specimen are performed and the results are compared with published ones. The similar analysis is performed for RC beam. Through this study, it is seen that predicted response has a good agreement with the experimental results. Using this verified numerical model, the strengthening effect of repaired with HPCC structure is analyzed through load-displacement curve and failure modes. Also, the same numerical analysis is performed in RC beam repaired with HPCC. The effect of HPCC ductility is estimated for the overall behavior of structures. Based on the results, the fundamental data are suggested for repaired structures with HPCC.

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A Study on the Error Analysis of the Numerical Solution using Inverse Method (역해석 기법을 이용한 수치해의 오차 분석 연구)

  • Yang, Sung-Wook;Lee, Sang-Chul
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.16 no.2
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    • pp.21-27
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    • 2008
  • An inverse method is introduced to construct the problem for the error analysis of the numerical solution of initial value problem. These problems constructed through this method have a known exact solution, even though analytical solutions are generally not obtainable. The process leading to the exact solution makes use of an initially available approximate numerical solution. A smooth interpolation of the approximate solution is forced to exactly satisfy the differential equation by analytically deriving a small forcing function to absorb all of the errors in the interpolated approximate solution. Using this special case exact solution, it is possible to investigate the relationship between global errors of a candidate numerical solution process and the associated tuning parameters for a given problem. Under the assumption that the original differential equation is well-posed with respect to the small perturbations, we thereby obtain valuable information about the optimal choice of the tuning parameters and the achievable accuracy of the numerical solution.

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Numerical Analysis an나bout Effects of Smear Zone in Vertical Drains on Consolidation (연직배수공법의 스미어존이 압밀에 미치는 영향에 관한 수치해석)

  • Yoo, Nam-Jae;Hong, Young-Kil;Woo, Young-Min;Jun, Sang-Hyun
    • Journal of Industrial Technology
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    • v.29 no.A
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    • pp.127-134
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    • 2009
  • In this paper, an numerical approach is performed to investigate the effects of smear zone, occurred by penetrating vertical drains, on consolidation behavior of soft clay deposits. Such a numerical analysis is applied to the field condition to confirm its applicability. Parametric numerical analyses is carried out to study influencing factors such as permeability in smear zone, boundary of smear zone and discharge capacity of vertical drains on the consolidation of soil. As results of analyses, for the given conditions of soil, degree of consolidation is getting faster with increase of permeability of vertical drain. Degree of consolidation is delayed with decrease of permeability of smear zone. As the ratio of drain width to smear zone increases, the degree of consolidation decreases. Proposed values of influencing factors by previous researchers is found to be reliable from results of numerical analyses with Cam-clay model.

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Numerical heat transfer analysis methodology for multiple materials with different heat transfer coefficient in unstructured grid for development of heat transfer analysis program for 3 dimensional structure of building (건물의 3차원 구조체에 대한 전열해석 프로그램 개발 중 서로 다른 열전도율을 갖는 복합재질 3차원 구조의 비정렬 격자에 대한 전산해석 방법)

  • Lee, Juhee;Jang, Jinwoo;Lee, Hyeonkyun;Lee, Youngjun;Lee, Kyusung
    • KIEAE Journal
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    • v.16 no.1
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    • pp.81-87
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    • 2016
  • Purpose: Heat transfers phenomena are described by the second order partial differential equation and its boundary conditions. In a three-dimensional structure of a building, the heat transfer phenomena generally include more than one material, and thus, become complicate. The analytic solutions are useful to understand heat transfer phenomena, but they can hardly be applied in engineering or design problems. Engineers and designers have generally been forced to use numerical methods providing reliable results. Finite volume methods with the unstructured grid system is only the suitable means of the analysis for the complex and arbitrary domains. Method: To obtain an numerical solution, a discretization method, which approximates the differential equations, and the interpolation methods for temperature and heat flux between two or more materials are required. The discretization methods are applied to small domains in space and time, and these numerical solutions form the descretized equations provide approximated solutions in both space and time. The accuracy of numerical solutions is dependent on the quality of discretizations and size of cells used. The higher accuracy, the higher numerical resources are required. The balance between the accuracy and difficulty of the numerical methods is critical for the success of the numerical analysis. A simple and easy interpolation methods among multiple materials are developed. The linear equations are solved with the BiCGSTAB being a effective matrix solver. Result: This study provides an overview of discretization methods, boundary interface, and matrix solver for the 3-dimensional numerical heat transfer including two materials.

A Intercomparison on the estimating shield TBM tunnel face pressure through analytical and numerical analysis (이론해와 수치해석적 검토를 통한 쉴드TBM 막장압 산정 결과 상호비교)

  • Jun, Gy-Chan;Kim, Dong-Hyun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.3
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    • pp.273-282
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    • 2016
  • This study estimates tunnel face pressure through existing 8 analytical equations and 3D numerical analysis, and compares and examines it. In general, the estimating tunnel face pressure of domestic shield TBM has been examined by a method according to analytical equation and empirical method, but numerical analysis is combined in a section passing complicated stratigraphic condition and special soil condition. Therefore, the researcher is to find a reliable method to examine of tunnel face pressure by confirming a correlation between tunnel face pressure estimated by equation and tunnel face pressure estimated by numerical analysis program. When tunnel face pressure is estimated, both analytical equation and numerical analysis were identically examined in soil conditions such as sandy soil and cohesive soil. In addition, existing analytical equation is used as equation, and 3D analysis copying construction process and shield tunnel as numerical analysis.

Base isolation performance of a cone-type friction pendulum bearing system

  • Jeon, Bub-Gyu;Chang, Sung-Jin;Kim, Sung-Wan;Kim, Nam-Sik
    • Structural Engineering and Mechanics
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    • v.53 no.2
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    • pp.227-248
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    • 2015
  • A CFPBS (Cone-type Friction Pendulum Bearing System) was developed to control the acceleration delivered to a structure to prevent the damage and degradation of critical communication equipment during earthquakes. This study evaluated the isolation performance of the CFPBS by numerical analysis. The CFPBS was manufactured in the shape of a cone differenced with the existing FPS (Friction Pendulum System), and a pattern was engraved on the friction surface. The natural frequencies of the CFPBS were evaluated from a free-vibration test with a seismic isolator system consisting of 4 CFPBS. To confirm the earthquake-resistant performance, a numerical analysis program was prepared using the equation of the CFPBS induced from the equations of motion. The equation reported by Tsai for the rolling-type seismic isolation bearings was proposed to design the equation of the CFPBS. Artificial seismic waves that satisfy the maximum earthquake scale of the Korean Building Code-Structural (KBC-2005) were created and verified to review the earthquake-resistant performance of the CFPBS by numerical analysis. The superstructural mass of the CFPBS and the skew angle of friction surface were considered for numerical analysis with El Centro NS, Kobe NS and artificial seismic waves. The CFPBS isolation performance evaluation was based on the numerical analysis results, and comparative analysis was performed between the results from numerical analysis and simplified theoretical equation under the same conditions. The validity of numerical analysis was verified from the shaking table test.