• Title/Summary/Keyword: 분리해석법

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Fatigue Damage of Quasi-Isotropic Composite Laminates (의사등방성 복합재 적층판의 피로손상)

  • 김인권
    • Composites Research
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    • v.12 no.4
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    • pp.8-16
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    • 1999
  • In this study, when the applied directions of tensile loading is changed fatigue damage of quasi-isotropic composite laminates was discussed. Low cycle fatigue tests of $[0/-60/+60]_s$ laminates and $[+30/-30/90]_s$ laminates were carried out. Material systems used were AS4/Epoxy and AS4/PEEK. The fatigue damage of $[+30/-30/90]_s$ laminates differed from that of $[0/-60/+60]_s$ laminates. The position of delamination generated at AS4/Epoxy and AS4/PEEK $[+30/-30/90]_s$ laminates appeared differently according to the kind of matrix. Critical values of strain energy release rate were obtained by using the strain measured at the initiation of delamination. The experimental results agreed well with the results obtained by the proposed method for determining strain energy release rate.

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Design of Optical Polarizer using Three-channel Rib-type Couplers (세 채널 Rib형 결합기를 이용한 광 편파기 설계)

  • Hong, Kwon-Eui;Lee, Won-Seock;Ho, Kwang-Chun
    • Journal of IKEEE
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    • v.7 no.1 s.12
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    • pp.16-21
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    • 2003
  • A rigorous modal transmission-line theory (MTLT) based on effective dielectric method (EDM) is introduced and developed to analyze the polarization beam-splitting of optical rib-type directional coupler with three guiding layers. Furthermore, to confirm the validity of approach proposed in this paper, we compare our results with those ones of BeamPROP, which is a commercial software package used widely. Consequently, the numerical results reveal that the hybrid modes incident into a guiding channel of rib-type coupler are split well through upper and lower guiding channels in a polarization length.

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Suitability of Counter-current Model for Biogas Separation Processes using Cellulose Acetate Hollow Fiber Membrane (셀룰로오스 아세테이트 중공사 분리막을 이용한 바이오가스 분리에 대한 향류 흐름 모델의 적용성)

  • Jung, Sang-Chul;Kwon, Ki-Wook;Jeon, Mi-Jin;Jeon, Yong-Woo
    • Journal of the Korea Organic Resources Recycling Association
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    • v.28 no.4
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    • pp.43-52
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    • 2020
  • As the membrane gas separation technology grows, various models were developed by numerous researchers to describe the separation process. In this work, the counter-current model was compared thoroughly with experimental data. Experimentally, hollow fiber membrane using CA module was prepared for the separation of biogas. The pure gas permeation properties of membrane module for methane, nitrogen, oxygen, and carbon dioxide were measured. The permeance of CO2 and CH4 were 25.82 GPU and 0.65 GPU, respectively. The high CO2/CH4 selectivity of 39.7 was obtained. the separation test for three different simulated mixed gases were carried out after pure gas test, and the gas concentration of the permeate at various stage-cut were measured from CA membrane module. Results showed that the experimental data agreed with the numerical simulation. A mathematical model has implemented in this study for the separation of biogas using a membrane module. The finite difference method (FDM) is applied to calculate the membrane biogas separation behaviors. Futhermore, the counter-current model can be considered as a convenient model for biogas separation process.

Numerical Study on Inverse Analysis Based on Levenberg-Marquardt Method to Predict Mode-I Adhesive Behavior of Fiber Metal Laminate (섬유금속적층판의 모드 I 접합 거동 예측을 위한 Levenberg-Marquardt 기법 기반의 역해석 기법에 관한 수치적 연구)

  • Park, Eu-Tteum;Lee, Youngheon;Kim, Jeong;Kang, Beom-Soo;Song, Woojin
    • Composites Research
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    • v.31 no.5
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    • pp.177-185
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    • 2018
  • Fiber metal laminate (FML) is a type of hybrid composites which consist of metallic and fiber-reinforced plastic sheets. As the FML has a drawback of the delamination that is a failure of the interfacial adhesive layer, the nominal stresses and the energy release rates should be determined to identify the delamination behavior. However, it is difficult to derive the nominal stresses and the energy release rates since the operating temperature of the equipment is restricted. For this reason, the objective of this paper is to predict the mode-I nominal stress and the mode-I energy release rate of the adhesive layer using the inverse analysis based on the Levenberg-Marquardt method. First, the mode-I nominal stress was assumed as the tensile strength of the adhesive layer, and the mode-I energy release rate was obtained from the double cantilever beam test. Next, the finite element method was applied to predict the mode-I delamination behavior. Finally, the mode-I nominal stress and the mode-I energy release rate were predicted by the inverse analysis. In addition, the convergence of the parameters was validated by trying to input two cases of the initial parameters. Consequently, it is noted that the inverse analysis can predict the mode-I delamination behavior, and the two input parameters were converged to similar values.

A Study on Long-Term Seepage Behaviour of Fill Dam by the Monitoring Data Analysis (계측자료 분석에 의한 필댐의 장기 침투거동 연구)

  • Chung, Kyujung;Lee, Song
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.9
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    • pp.15-25
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    • 2010
  • The main objective of this study was to offer informations about long-term seepage behavioral characteristics and to find a leakage safety management method for Juam Dam and Imha Dam, a central cored rockfill dams in Korea by the evaluating the automatically monitored leakage data. In the water leakage monitoring of fill dam, the generation of abnormal water leakage is difficult to directly detect due to the effect of outside factors such as the component of rainfall inherent in the observation value. Therefore, conventionally estimation methods of water leakage quantity were applied by multiple regression analysis considering reservoir water level, rainfall, etc.. However, the estimated error of rainfall component is relatively big in these method. This paper identifies the seepage characteristic of each dams which is not directly affected by rainfall through the hydrograph separation analysis and 3 dimensional analytical method, and thinks a leakage management method. It was noticed that two dams had site specific seepage behaviour features and were in stable state with the decreasing leakage quantity. It was also found that hydrograph separation method might be applicable to leakage safety management method.

A Study on the Separation of $CO_2$from Flue Gas by Chemical Absorption (화학흡수법에 의한 연소폐가스 중 지구온난화 가스 $CO_2$분리에 관한 연구)

  • 안성우;김영국;송호철;박진원
    • Journal of Energy Engineering
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    • v.6 no.2
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    • pp.203-211
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    • 1997
  • This study is on the separation of Global warming effect gas, CO$_2$by chemical absorption from mixture of CO$_2$-N$_2$which was modeled after flue gas of fire power plant. Investigation of optimum condition for absorbent was carried out by using sparged vessel apparatus. Through packed tower experiments, applicabilities of two absorption models were tested by comparing experimental results with theoretical values. Absorbent used in the experiments was Monoethanolamine (MEA) and gas mixture was made in the mole composition of 15% CO$_2$and 85% N$_2$. Through estimations of CO$_2$loading and CO$_2$removal efficiency, optimum concentration of absorbent was found in the range of 4-5 M. To find a rate of absorption, an enhancement factor was introduced. Values of rate of absorption were calculated by Film model and Higbie model, respectively. Higbie model showed good agreement with experimental results. Therefore, this models is considered to be applicable to the CO$_2$separation process for flue gas from fire power plant.

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A Design of Chemical Analysis for the CD-R Recording Layer's Nano-structure and Composition Analysis (CD-R 기록층의 나노구조 및 성분 분석을 위한 화학분석 설계 사례)

  • Cho, Namjun
    • The Journal of Korean Institute for Practical Engineering Education
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    • v.4 no.2
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    • pp.84-90
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    • 2012
  • It is described that the total analysis of CD-R, a digital recording media, including the planning and performing chemical analysis of cross sectional structure of recording layer, dye composition and chemical structure as an example of design for chemical analysis. Since chemical analysis of unknown sample is often involved the complicated process requiring many experiences and knowledge, students feel difficulties in planning the procedure of chemical analysis and selecting analytical methods. Thus, an example of chemical analysis is provided here to help student understanding the hole procedure of CD-R analysis. In this study, SEM is used to determine the cross sectional structure of PC substrate and recoding layer of CD-R. The dyes in recording layer is dissolved with solvent and separated with using TLC, analyzed with using UV-Vis absorption spectrometer. Then, the chemical structure of each component is determined with using GC-MS, NMR and mass spectrometer.

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Numerical Simulation of Dynamic Soil-pile-structure Interaction in Liquefiable Sand (액상화 가능한 지반에 근입된 지반-말뚝-구조물 동적 상호작용의 수치 모델링)

  • Kwon, Sun-Yong;Yoo, Min-Taek;Kim, Seok-Jung
    • Journal of the Korean Geotechnical Society
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    • v.34 no.7
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    • pp.29-38
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    • 2018
  • Three-dimensional continuum modeling of dynamic soil-pile-structure interaction embedded in a liquefiable sand was carried out. Finn model which can model liquefaction behavior using effective stress method was adopted to simulate development of pore water pressure according to shear deformation of soil directly in real time. Finn model was incorporated into Non-linear elastic, Mohr-Coulomb plastic model. Calibration of proposed modeling method was performed by comparing the results with those of the centrifuge tests performed by Wilson (1998). Excess pore pressure ratio, pile bending moment, pile head displacement-time history according to depth calculated by numerical analysis agreed reasonably well with the test results. Validation of the proposed modeling method was later performed using another test case, and good agreement between the computed and measured values was observed.

Dynamic Analysis of Offshore Structures Considering External Fluid-Structure Interaction (외부유체-구조물의 상호작용을 고려한 해양구조물의 동적해석)

  • Hwang, Chul-Sung;Paik, In-Yeol
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.1
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    • pp.271-281
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    • 2005
  • The effects of radiation damping is used to compensate the truncated boundary which is relatively close to the structure-fluid interface in the fluid element surrounding the submerged structures. An efficient ring element is presented to model the shell and fluid element which fully utilizes the characteristics of the axisymmetry. The computational model uses the technique which separate the meridional shape and circumferential wave mode and gets similar result with the exact solution in the eigenvalues and the earthquake analysis. The fluid-structure interaction techniques is developed in the finite element analysis of two dimensional problems using the relations between pressure, nodal unknown acceleration and added mass assuming the fluid to be invicid, incompressible and irrotational. The effectiveness and efficiency of the technique is demonstrated by analyzing the free vibration and seismic analysis using the added mass matrix considering the structural deformation effect.

Groundwater Flow Analysis around Hydraulic Excavation Damaged Zone (수리적 굴착손상영역에서의 지하수유동 특성에 관한 연구)

  • Park, Jong-Sung;Ryu, Dong-Woo;Ryu, Chang-Ha;Lee, Chung-In
    • Tunnel and Underground Space
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    • v.17 no.2 s.67
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    • pp.109-118
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    • 2007
  • The excavation damaged zone (EDZ) is an area around an excavation where in situ rock mass properties, stress condition. displacement. groundwater flow conditions have been altered due to the excavation. Various studies have been carried out on EDZ, but most studies have been focused on the mechanical bahavior of EDZ by in situ experiment. Even though the EDZ could potentially form a high permeable pathway of groundwater flow, only a few studies were performed on the analysis of groundwater flow in EDZ. In this study, the' hydraulic EDZ' was defined as the rock Lone adjacent to the excavation where the hydraulic aperture has been changed due to the excavation. And hydraulic EDZ (hydraulic aperture changed zone) estimated by two-dimensional DEM program was considered in three-dimensional DFN model. From this approach the groundwater flow characteristics corresponding to hydraulic aperture change were examined. Together. a parametric study was performed to examine the boundary conditions that frequently used in DFN analysis such as constant head or constant flux condition. According to the numerical analysis, hydraulic aperture change induced by the hydraulic-mechanical interaction becomes one of the most important factors Influencing the hydraulic behavior of jointed rock masses. And also from this study, we suggest the proper boundary condition in three-dimensional DFN model.