• Title/Summary/Keyword: 모사 재료

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Evaluation of Performance of Expansive Material for Restoration of Underground Cavity and Stress Release Zone (지하공동 및 이완영역 복구를 위한 팽창성 재료의 성능 평가)

  • Lee, Kicheol;Choi, Byeong-Hyun;Bak, Jongho;Kim, Dongwook
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.4
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    • pp.141-155
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    • 2018
  • Recently, the number of ground subsidence resulting from underground cavity has been increased. Accordingly, the importance of restoration of stress release zone around the underground cavity has been emphasized. The stress release zone is composed of low density soils having extremely low stiffness and degree of compaction, which can lead to additional cavity expansion and collapse of overlying ground. Therefore, in this study, the suitability of restoration method of underground cavity using expansive material for reinforcement of stress release zone around the cavity is verified. The basic physical properties and expansion characteristics of the expansive material were examined. The experiment equipment capable simulating of stress release zone was developed and is used to investigate the effect of expanding material on stress release zone. The stress release zone was simulated using the spring in numerical analysis. The factors of the volume ratio of the underground cavity to the expansion material, the degree of stress relaxation, and the shape of the cavity were varied in numerical simulations, and the behavior of stress release zone was analyzed based on the numerical analysis results. Analysis variables are factors that affect each other. Also, filling of underground cavity and capacity of restoration of stress release zone were confirmed when the expansive material was inserted into underground cavity.

Immunocytochemical Study on the Enteroendocrine Cells in the Gastrointestinal Tracts of the Korean Snakes (한국산 뱀목 위장관 점막이 장내분비세포에 대한 면역세포화학적 연구)

  • 진원주;조운복;최월봉
    • The Korean Journal of Zoology
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    • v.33 no.3
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    • pp.276-296
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    • 1990
  • This study attempts to investigate several enteroendocrine cells in the gastrointestinal epithelia of the Korean snakes (Dinodon rufozonatum rufozonotum Rhabdophis tigrina tigrina, Enhydris rufodorsata, Agkistrodon blomhoffii brevicaudus, Agkistrodon saxatilis, Agkistodon calginosus). For a light-microscopical examination of immunocytochemistry, the paraffin sections (5 $\mu$ m) of tissue specimens taken from the various parts of the gastrointestinal tract were stained immunocytochemically by PAP procedure with 10 antisera. The frequency of enteroendocrine cells per unit area (mm$^2$) of each mucosa were counted and the shapes of the cells were observed. In Dinodon rufozonatum rufozonatum, Rhobdophis tigrina tigrina, Enhydris rufodorsata, Agkistrodon saxatilis and Agkistrodon caliginosus, cholecystokinin (CCK)-8, gastrin, pancreatic polypeptide (PP) and serotonin cells were observed. But the freuqency of these immunoreactive cells differ trom each portion of gastrointestinal tracts of all species, respectively. In Agkistrodon blomhoffii brevicaudus, CCK-8, gastrin and serotonin cells were observed. CCK-8 and serotonin cells were found in whole gastrointestinal tracts and gastrin cells were observed in pylorus and mucosa of small intestine. The frequency of these cells was different from each portion. The shapes of CCK-8, gastrin, PP and serotonin cells were pyramidal or oval and closed type in stomach. A large number of these cells were spindle in shape and open type in small intestine and anterior pant of large intestine, whereas some cells were closed type. In posterior part of large intestine and rectum, these cells were oval in shape and closed type.

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Functionally Gradient Materials (FGMs) for Improved Thermo-mechanical Properties (열.기계적 특성 향상을 위한 경사기능 재료 (FGM))

  • 박성용;김진홍;김문철;박찬경
    • Journal of Powder Materials
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    • v.11 no.1
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    • pp.8-15
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    • 2004
  • The basic concept of functionally gradient materials (FGM) is to fabricate materials type having possibilities of applications in various fields by changing their intrinsic properties with continuous gradient. The present communication has reviewed the developments and applications of various FGMs designed for improved thermo-mechanical properties, in which the thermal protective and wear resistant materials are especially focused. Effects of thermo-mechanical properties and limits of FGMs designed for high temperature applications were mainly understood in terms of residual stress evolved from the design and fabrication. In addition, FGMs applied in structural parts were also introduced and discussed in terms of typical fabrication method for FGMs.

Finite element analysis of the PZT 3203HD bimorph beam actuator based on material non-linear characteristics (박막형 압전재료 3203HD의 재료 비선형성을 고려한 바이모프 보 작동기의 비선형 유한 요소해석)

  • Jang, Sung-Hoon;Kim, Young-Sung;Lee, Sang-Ki;Park, Hoon-Cheol;Yoon, Kwang-Joon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.4
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    • pp.18-23
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    • 2004
  • In this paper, material non-linear behavior of PZT wafer(3203HD, CTS) under high electric field and stress is experimentally investigated and the non-linearity of the PZT wafer is numerically simulated. Empirical functions that can represent the non-linear behavior of the PZT wafer have been extracted based on the measured piezo-strain under stress. The functions are implemented in an incremental finite element formulation for material non-linear analysis. New definition of the piezoelectric constant and the incremental strain are incorporated into the finite element formulation for a better reproduction of the non-linear behavior. With the new definition of the in incremental piero-strain the measured non-linear behavior of the PZT wafer has been accurately reproduced even for high electric field. For validation of the measured non-linear characteristics and the proposed approach, a PZT bimorph beam actuator has been numerically and experimentally tested. The predicted actuation displacement, based on the material nonlinear finite element analysis, showed a good agreement with the measured one.

Study on the numerical model of complex permittivity of composites based on the percolation theory (퍼콜레이션 이론에 기초한 복합재료의 복소 유전율 모델에 대한 연구)

  • Kim, Jin-Bong;Lee, Sang-Kwan;Kim, Chun-Gon
    • Composites Research
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    • v.22 no.3
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    • pp.44-54
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    • 2009
  • In this paper, we proposed a numerical model the complex permittivity for the E-glass fabric/epoxy composite laminate containing electrical conductive carbon black. The model is based on the percolation theory and for the composites over than the percolation threshold and in higher frequency band in that the AC conductivity is fully proportional to the frequency. The measurement for the complex permittivity wasperformed at the frequency band of 0.5 GHz $\sim$ 18.0 GHz using a vector network analyzer with a 7 mm coaxial air line. The proposed model is composed of the numerical equations of the scaling law used in percolation theory and constants obtained from experiments to quantify the model itself. The model describes the complex permittivity as the function of frequency and filler concentration. The model was verified by being compared with the measurements.

Three Dimensional Analysis of Polymer Flow (고분자 유동의 3차원 해석)

  • 이석원;윤재륜
    • Proceedings of the Korean Fiber Society Conference
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    • 2003.04a
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    • pp.187-190
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    • 2003
  • 복잡한 형상을 지나는 고분자 유체의 유동 해석은 학문적인 관심 뿐만 아니라 고분자 가공 공정을 이해하는데 많은 도움을 주기 때문에 산업적으로도 그 중요성이 높다. 그러나, 기하학적 복잡성이나 재료 자체의 비선형성으로 인하여 해석적인 접근에 한계가 있기 때문에 다양한 수치 해석법을 이용한 유동 해석이 주를 이루고 있다. 특히 고분자 가공 공정의 수치 모사에 있어서는 수치 해석법을 적용하는데 있어서도 완전한 3차원 해석보다는 여러 가지 가정을 적용한 2차원 내지는 2.5차원 해석이 주를 이루고 있어서도 완전한 3차원 해석보다는 여러 가지 가정을 적용한 2차원 내지는 2.5차원 해석이 주를 이루고 있는 실정이다. (중략)

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Simulation of liquid crystal polymer injection molded parts with thin wall and multi holes (다공성 액정고분자 박판의 사출성형 전산모사)

  • 정만석;김성훈
    • Proceedings of the Korean Fiber Society Conference
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    • 2001.10a
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    • pp.287-290
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    • 2001
  • 최근 정보통신 산업의 급속한 발전으로 이동 통신용 단말기 및 반도체 칩 케리어 등의 플라스틱 부품의 초소형 경량화 요구가 증대되고 있다. 미세 사출성형용(micro injection molding) 박판의 사출을 위한 미세사출 성형 고분자 재료는 매우 우수한 용융 유동 특성을 가져야 하고, 반도체나 소형 엔지니어링 부품으로 사용하려면 높은 인장강도, 충격강도 및 치수안정성을 가져야 한다. (중략)

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Research of Vibration Analysis and Resonance Avoidance Design of Composite Quadcopter (복합재 쿼드콥터의 진동 특성 분석과 공진 회피에 대한 연구)

  • Kim, Sang-Ryul;Kim, Wie-Dae
    • Composites Research
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    • v.33 no.3
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    • pp.133-139
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    • 2020
  • In this research, the vibration characteristics of composite quadcopter are analyzed, and avoidance design and analysis are performed to avoid resonance. The full platform of a commercial quadcopter with composite rotor arm is analyzed to see the vibration characteristics using FEM program. The manufactured stacking sequences of rotor arm is used for analysis, and the natural frequencies are compared with experimental results and simple analytic model results. It is also confirmed that the natural frequency of the particular mode is included within the operation range of the motor. The resonance avoidance design is carried out by selecting three variables from the existing model: stacking sequence, rotor-arm pipe length, and pipe thickness.

A Study on Bending Behaviors of Laminated Composites using 2D Strain-based Failure Theory (2D 변형률 파손 이론을 이용한 복합재료의 굽힘 거동 해석)

  • Kim, Jin-Sung;Roh, Jin-Ho;Lee, Soo-Yong
    • Journal of Aerospace System Engineering
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    • v.11 no.5
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    • pp.13-19
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    • 2017
  • In this study, the bending analysis of composite laminates using the classical laminated theory is investigated. A piece-wise linear incremental approach is employed to describe the nonlinear mechanical behavior of the composite laminates, and a 2D strain-based interactive failure theory is employed to predict the ultimate flexural loads. The 3-point bending tests are performed for cross-ply and quasi-isotropic laminates. The analysis results with the failure theory are verified by comparing the analysis findings to the experimental outcome.

Numerical Assessment of Tensile Strain Capacity for X80 Line Pipe Using GTN Model (GTN 모델을 이용한 X80 라인파이프의 인장 변형성능 해석)

  • Yoon, Young-Cheol;Kim, Ki-Seok;Lee, Jae Hyuk;Cho, Woo-Yeon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.6
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    • pp.979-990
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    • 2016
  • This study presents a nonlinear finite element procedure involving a phenomenological model to validate the tensile strain capacity of the X80 line pipe developed for the strain-based design purpose. The procedure is based on the Gurson-Tvergaard-Needleman (GTN) model, which models nucleation, growth and coalescence of void volume fraction occurred inside a metal. In this study, the user-defined material module (UMAT) is implemented in the commercial finite element platform ABAQUS and is applied to the nonlinear damage analysis of steel specimens. Material parameters for the nonlinear damage analysis of base and weld metals are calibrated from numerical simulations for the tensile tests of round bar and full thickness specimens. They are then employed in the numerical simulations for SENT (Single Edge Notch Tension) test and CWPT (Curved Wide Plate Test) and in the simulations, the tensile strain capacities are naturally evaluated. Comparison of the numerical results with the experimental results and the conventional empirical formulae shows that the proposed numerical procedure can fairly well predict the tensile strain capacity of X80 line pipe. So, it is readily expected to be effectively applied to the strain-based design procedure.