• Title, Summary, Keyword: Inhomogeneous

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Simulation of Inhomogeneous Texture through the Thickness Direction during Hot Rolling Deformation in Strip Cast Al-5wt%Mg Alloy (박판 주조된 Al-5 wt%Mg 합금의 열간압연 시 두께방향 불균일 집합조직 시뮬레이션)

  • Song, Young-Sik;Kim, Byoung-Jin;Kim, Hyoung-Wook;Kang, Seok-Bong;Choi, Shi-Hoon
    • Korean Journal of Metals and Materials
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    • v.46 no.3
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    • pp.135-143
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    • 2008
  • The inhomogeneous texture through the thickness direction can be developed during hot rolling deformation in aluminum alloy. In this study, the inhomogeneous texture evolution through the thickness direction during hot rolling deformation in Al-5 wt%Mg alloy produced by a new strip casting technology was measured experimentally. Macrotexture measurement was conducted using X-ray diffractometer. A finite element analysis with ABAQUS/StandardTM and rate sensitive polycrystal model were used to predict the evolution of hot rolling texture. The experimental results of Al-5 wt%Mg alloy were compared with calculated results. The shear texture components tend to be increased at the surface region of the hot-rolled specimen. It is found that triclinic sample symmetry is more accurate assumption for texture analysis and simulation in the surface region of hot-rolled aluminum alloy.

Evaluation of Planning Dose Accuracy in Case of Radiation Treatment on Inhomogeneous Organ Structure (불균질부 방사선치료 시 계획 선량의 정확성 평가)

  • Kim, Chan Yong;Lee, Jae Hee;Kwak, Yong Kook;Ha, Min Yong
    • The Journal of Korean Society for Radiation Therapy
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    • v.25 no.2
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    • pp.137-143
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    • 2013
  • Purpose: We are to find out the difference of calculated dose of treatment planning system (TPS) and measured dose in case of inhomogeneous organ structure. Materials and Methods: Inhomogeneous phantom is made with solid water phantom and cork plate. CT image of inhomogeneous phantom is acquired. Treatment plan is made with TPS (Pinnacle3 9.2. Royal Philips Electronics, Netherlands) and calculated dose of point of interest is acquired. Treatment plan was delivered in the inhomogeneous phantom by ARTISTE (Siemens AG, Germany) measured dose of each point of interest is obtained with Gafchromic EBT2 film (International Specialty Products, US) in the gap between solid water phantom or cork plate. To simulate lung cancer radiation treatment, artificial tumor target of paraffin is inserted in the cork volume of inhomogeneous phantom. Calculated dose and measured dose are acquired as above. Results: In case of inhomogeneous phantom experiment, dose difference of calculated dose and measured dose is about -8.5% at solid water phantom-cork gap and about -7% lower in measured dose at cork-solid water phantom gap. In case of inhomogeneous phantom inserted paraffin target experiment, dose difference is about 5% lower in measured dose at cork-paraffin gap. There is no significant difference at same material gap in both experiments. Conclusion: Radiation dose at the gap between two organs with different electron density is significantly lower than calculated dose with TPS. Therefore, we must be aware of dose calculation error in TPS and great care is suggested in case of radiation treatment planning on inhomogeneous organ structure.

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Non-uniform Failure in Superplastic Ti-6Al-4V Alloy (초소성 Ti-6Al-4V 합금에서의 불균일 파손)

  • 김태원
    • Transactions of Materials Processing
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    • v.9 no.6
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    • pp.663-669
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    • 2000
  • A material model has been presented, at the continuum level, for the representation of superplastic deformation coupled with microstructural evolution. The model presented enables the effects of the spatial variation of distributions of grain size to be predicted at the process level. The model has been tested under conditions of both homogeneous and inhomogeneous stress and strain by carrying out detailed comparison of predicted distributions of grain size and their evolutions with experimentally obtained data. Experimental measurements have shown the extent of the spatial variation of the distribution of grain size that exists in the titanium alloy, Ti-6Al-4V. It is shown that whilst not large, the variations in grain size distributions are sufficient to lead to the development of inhomogeneous deformation in test pieces, which ultimately result in localisation of strain and failure.

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Combustion Characteristics of Methane-Air Mixture in a Constant Volume Combustion Chamber(2) : Inhomogeneous Charge (정적연소기에서의 메탄-공기 혼합기의 연소특성(2) : 비균질급기)

  • 최승환;전충환;장영준
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.4
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    • pp.29-36
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    • 2003
  • A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at spark plug and the combustion characteristics of inhomogeneous charge methane-air mixture under several parameters. The flow characteristics such as mean velocity and turbulence intensity was analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer was used to investigate the effect of initial charge pressure, excess air ratio and ignition times on combustion pressure and combustion duration. Mean velocity and turbulence intensity had the maximum value at 200 or 300ms and then decreased to beneath 0.05m/s gradually at 3 seconds. Second mixture is accompanied by an increase in the combustion rate, and that the higher the mass which is added in the second stage injection, the faster the burn rate.

Electromagnetic Scattering Analysis from Inhomogeneous Material Scatterers (불균질 매질내에서의 전자파 산란 해석)

  • 김태용;김석재
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.3
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    • pp.478-484
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    • 2003
  • The electromagnetic wave scattering problems from inhomogeneous material bodies are considered. The formulation is made in terms of mixed potentials for the moment methods (MoM). The surfaces of a three-dimensional inhomogeneous scatterer of arbitrary shape are divide into triangular patches for descretization. Application of the boundary conditions leads to the coupled surface integral equations to be satisfied for the unknown surface equivalent electric and magnetic currents. The radar cross-section (RCS) for some structures is computed and the results are compared with the reported data.

A Study on the Fracture Resistance at the Crack Tip in Dual Phase Steel (복합조직강 의 균열선단 에서의 파괴저항 에 관한 연구)

  • 김정규;오재민;김형채
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.5
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    • pp.564-571
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    • 1985
  • The estimation of fracture toughness in inhomogeneous material is still insufficient because it is difficult to get information of fracture initiation at the crack tip. Therefore, martensite-ferrite dual phase steel was prepared for a model material and micro-fracture behavior was investigated in the region of pre-fatigue crack in order to understand the characteristic of fracture resistance in inhomogeneous materials. In the case of severely inhomogeneous state, micro-fracture appearance is not distributed homogenously so that the estimation of fracture toughness is hardly possible. On the other hand when the grain size is refined or the strength of martensite is lowered, micro-fracture appearance is distributed homogenously and fracture toughness remarkably increases.

Evaluation of Inhomogeneous Deformation and Stress Concentration In Polymer Composites Injection Weld by means of Thermoelastic Techniques

  • Lim, Jae-Kyoo;Kim, Yon-Jig
    • Journal of Mechanical Science and Technology
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    • v.15 no.12
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    • pp.1616-1622
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    • 2001
  • Fiber composite materials are widely used in aerospace industries due to their high specific strength and stiffness. Especially, the increasing use of polymer composite materials for injection of automobile components has led to a considerable interest in the application of stress pattern analysis by thermal emission to these composite materials. Therefore, in this study the microstructure of glass fiber orientation at the parent and weld line of polycarbonate is observed by a light transmission. And we also investigate a stress concentration model of a notch including short glass fibers. Especially the polymer injection weld reorients the fiber to suggest a new method for the evaluation of inhomogeneous deformation.

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Natural Frequencies for Inhomogeneous Beams by Differential Transformation (미분변환에 의한 비균질 보의 진동해석)

  • Mun, Kwon-Kyung;Jae, Shin-Yung;Ryu, Yung-Soon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.617-621
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    • 2001
  • This paper presents the application of the technique of differential transformation to find the vibration frequencies for inhomogeneous beams with one sliding support, the other clamped and the other pinned boundary conditions. Numerical calculations are carried out. The frequencies obtained from the differential-transformation solutions are compared to published results to demonstrate the accuracy and flexibility of the method.

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POISSON APPROXIMATION OF INDUCED SUBGRAPH COUNTS IN AN INHOMOGENEOUS RANDOM INTERSECTION GRAPH MODEL

  • Shang, Yilun
    • Bulletin of the Korean Mathematical Society
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    • v.56 no.5
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    • pp.1199-1210
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    • 2019
  • In this paper, we consider a class of inhomogeneous random intersection graphs by assigning random weight to each vertex and two vertices are adjacent if they choose some common elements. In the inhomogeneous random intersection graph model, vertices with larger weights are more likely to acquire many elements. We show the Poisson convergence of the number of induced copies of a fixed subgraph as the number of vertices n and the number of elements m, scaling as $m={\lfloor}{\beta}n^{\alpha}{\rfloor}$ (${\alpha},{\beta}>0$), tend to infinity.

Research of Foresight Knowledge by CMAC based Q-learning in Inhomogeneous Multi-Agent System

  • Hoshino, Yukinobu;Sakakura, Akira;Kamei, Katsuari
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • pp.280-283
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    • 2003
  • A purpose of our research is an acquisition of cooperative behaviors in inhomogeneous multi-agent system. In this research, we used the fire panic problem as an experiment environment. In Fire panic problem a fire exists in the environment, and follows in each steps of agent's behavior, and this fire spreads within the constant law. The purpose of the agent is to reach the goal established without touching the fire, which exists in the environment. The fire heat up by a few steps, which exists in the environment. The fire has unsureness to the agent. The agent has to avoid a fire, which is spreading in environment. The acquisition of the behavior to reach it to the goal is required. In this paper, we observe how agents escape from the fire cooperating with other agents. For this problem, we propose a unique CMAC based Q-learning system for inhomogeneous multi-agent system.

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