• Title/Summary/Keyword: transformation region

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A Simple Calculational Method by using Modified Von Mises Transformation applied to the Coaxial Turbulent Jet Mixing (유동함수를 이용한 난류제트혼합유동 계산에 관한 연구)

  • Choi Dong-Whan
    • Journal of the Korean Society of Propulsion Engineers
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    • v.9 no.2
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    • pp.97-104
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    • 2005
  • A simple but efficient grid generation technique by using the modified compressible form of stream function has been formulated. Transformation of a physical plane to a streamline plane, the Von Mises Transformation, has been widely used to solve the differential equations governing flow phenomena, however, limitation arises in low velocity region of boundary layer, mixing layer and wake region where the relatively large grid spacing is inevitable. Modified Von Mises Transformation with simple mathematical adjustment for the stream function is suggested and applied to solve the confined coaxial turbulent jet mixing with simple $\kappa-\epsilon$ turbulence model. Comparison with several experimental data of axial mean velocity, turbulent kinetic energy, and Reynolds shear stress distribution shows quite good agreement in the mixing layer except in the centerline where the turbulent kinetic energy distributions were somewhat under estimated. This formulation is strongly suggested to be utilized specially for free turbulent mixing layers in axisymmetric flow conditions such as the investigation of mixing behavior, jet noise production and reduction for Turbofan engines.

Molecular Dynamic Simulation of Nano Indentation and Phase Transformation (분자동역학을 이용한 나노 인덴테이션과 상변화 해석 연구)

  • 김동언;손영기;임성한;오수익
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.10a
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    • pp.339-346
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    • 2003
  • Molecular dynamic simulations of nano indentation on single-crystal silicon (100) surface were performed using diamond indentor. Silicon substrate and diamond indentor were modeled diamond structure with Tersoff potential model. Phase transformation of silicon, incipient plastic deformation, change of incident temperature distribution are investigated through the change of potential energy distribution, displacement-load diagram, the change of kinetic energy distribution and displacements of silicon atoms. Phase transformation is highly localized and consists of a high-density region surrounding the tip. Axial load linearly increased according to the indenting depth. Number of atoms with high kinetic energy increased at the interface between substrate and indentor tip.

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Effect of Pb Content on the Phase Transformation of Sputter-Deposited PZT Thin Film During RTA (PZT 박막의 급속열처리시 Pb 함량이 상변태에 미치는 영향)

  • 주재현;길덕신;주승기
    • Journal of the Korean Ceramic Society
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    • v.30 no.10
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    • pp.803-810
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    • 1993
  • PbxZr0.4Ti0.6O3 thin films were prepared by reactive co-sputtering and annealed by RTA(Rapid Thermal Annealing) process. Effect of Pb content in PbxZr0.4Ti0.6O3 films on the phase transformation was intensively studied. It has been found out that depending on the Pb content as well as RTA temperature, crystal structure of PbxZr0.4Ti0.6O3 films change greatly. It turned out that transformation temperature for perovskite can be lowered and the width of transition temperature region was reduced by increasing Pb content in the film. And the lattice was expanded with increasing Pb content. With increasing RTA temperature, as-deposited phase was transformed into perovskite through three different transformation paths depending on Pb content. It was confirmed that activation energies for nucleation of perovskite structure are much larger than those of its growth.

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A Study on the Prediction Modeling of Phase Transformation in the CGHAZ of Structural Steel Weld (구조용강 용접부 CGHAZ의 상변태 예측 Modeling에 관한 연구)

  • 조일영;이경종;이창희
    • Journal of Welding and Joining
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    • v.16 no.3
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    • pp.74-84
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    • 1998
  • The microstructures of the HAZ (Heat Affected Zone) are generally different from the base metal due to rapid thermal cycle during welding process. Particuraly, CGHAZ (Coarsened Grain Heat Affected Zone) near the fusion line is the most concerned region in which many metallurgical and mechanical discontinuities have been normally generated. A computer program by the numerical formularization of phase transformation during cooling with different rates was developed to generate the CCT diagram, and to predict microstructural (phase) changes in the CGHAZ. In order to verify simulated results, isothermal and continuous cooling transformation experiments were conducted. The simulated and experimental results showed that the developed computer model could successfully predict the room temperature microstructural changes (changes in volume fraction of phases) under various welding conditions (heat input & cooling rate $(Δt_{8/5})$).

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Bottle Label Segmentation Based on Multiple Gradient Information

  • Chen, Yanjuan;Park, Sang-Cheol;Na, In-Seop;Kim, Soo-Hyung;Lee, Myung-Eun
    • International Journal of Contents
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    • v.7 no.4
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    • pp.24-29
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    • 2011
  • In this paper, we propose a method to segment the bottle label in images taken by mobile phones using multi-gradient approaches. In order to segment the label region of interest-object, the saliency map method and Hough Transformation method are first applied to the original images to obtain the candidate region. The saliency map is used to detect the most salient area based on three kinds of features (color, orientation and illumination features). The Hough Transformation is a technique to isolated features of a particular shape within an image. Therefore, we utilize it to find the left and right border of the bottle. Next, we segment the label based on the gradient information obtained from the structure tensor method and edge method. The experimental results have shown that the proposed method is able to accurately segment the labels as the first step of product label recognition system.

Design of Continuous-Time System Using Bilinear Transformation (쌍선형 변환에 의한 연속 시간계의 설계)

  • Kim, Sang-Bong;An, Hwi-Ung
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.25 no.3
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    • pp.137-142
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    • 1989
  • A pole assignment problem in a specified region is solved using a bilinear transformation method. It is well known that the problem designing discrete-time system or vice versa is called redesign problem, But there is not so much study that is cyclic type of design, i.e. from continuous system to discrete system and from the latter to the former system. In this paper, the cyclic type of design for the continuous-time system is proposed using the bilinear transformation. In the view of a pole assignment method with poles in a specified region, it will be possible to design a regulator or a servo system considering damping ratio, stability degree and band with which are resulted to the characteristics of the closed-loop system.

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Continuous Cooling Transformation, Microstructure and Mechanical Properties of High-Strength Low-Alloy Steels Containing B and Cu (B과 Cu가 포함된 고강도 저합금강의 연속냉각 변태와 미세조직 및 기계적 특성)

  • Hwang, Byoungchul
    • Korean Journal of Materials Research
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    • v.23 no.9
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    • pp.525-530
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    • 2013
  • This study investigated the continuous cooling transformation, microstructure, and mechanical properties of highstrength low-alloy steels containing B and Cu. Continuous cooling transformation diagrams under non-deformed and deformed conditions were constructed by means of dilatometry, metallographic methods, and hardness data. Based on the continuous cooling transformation behaviors, six kinds of steel specimens with different B and Cu contents were fabricated by a thermomechanical control process comprising controlled rolling and accelerated cooling. Then, tensile and Charpy impact tests were conducted to examine the correlation of the microstructure with mechanical properties. Deformation in the austenite region promoted the formation of quasi-polygonal ferrite and granular bainite with a significant increase in transformation start temperatures. The mechanical test results indicate that the B-added steel specimens had higher strength and lower upper-shelf energy than the B-free steel specimens without deterioration in low-temperature toughness because their microstructures were mostly composed of lower bainite and lath martensite with a small amount of degenerate upper bainite. On the other hand, the increase of Cu content from 0.5 wt.% to 1.5 wt.% noticeably increased yield and tensile strengths by 100 MPa without loss of ductility, which may be attributed to the enhanced solid solution hardening and precipitation hardening resulting from veryfine Cu precipitates formed during accelerated cooling.

DNAJB9 Inhibits p53-Dependent Oncogene-Induced Senescence and Induces Cell Transformation

  • Lee, Hyeon Ju;Jung, Yu-Jin;Lee, Seungkoo;Kim, Jong-Il;Han, Jeong A.
    • Molecules and Cells
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    • v.43 no.4
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    • pp.397-407
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    • 2020
  • DNAJB9 is known to be a member of the molecular chaperone gene family, whose cellular function has not yet been fully characterized. Here, we investigated the cellular function of DNAJB9 under strong mitogenic signals. We found that DNAJB9 inhibits p53-dependent oncogene-induced senescence (OIS) and induces neoplastic transformation under oncogenic RAS activation in mouse primary fibroblasts. In addition, we observed that DNAJB9 interacts physically with p53 under oncogenic RAS activation and that the p53-interacting region of DNAJB9 is critical for the inhibition of p53-dependent OIS and induction of neoplastic transformation by DNAJB9. These results suggest that DNAJB9 induces cell transformation under strong mitogenic signals, which is attributable to the inhibition of p53-dependent OIS by physical interactions with p53. This study might contribute to our understanding of the cellular function of DNAJB9 and the molecular basis of cell transformation.

A study on the mechanical properties of austempered low-alloy ductile cast iron (오스템퍼링한 低合金 球狀黑鉛鑄鐵의 機械的 性質에 관한 硏究)

  • 강명순;박흥식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.6
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    • pp.1296-1302
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    • 1988
  • The study has been carried out under various experimental conditions to investigate mechanical properties by the transformation conditions of austempered low-alloy ductile cast iron. The amount of retained austenite and bainite after quenching was determined by the X-ray diffractometer and the point counting method and which the microstructure was investigated by the S.E.M. The mechanical properties of austempered low-alloy ductile cast iron can be varried over a comparatively wide range by changing the transformation conditions. During isothermal transformation of austenite in the bainite region, low-alloy ductile cast iron austempered at holding time of 40 minute has the maximum volume fraction(24%) of retained austenite in the cast iron matrix and which optimum values of mechanical properties correspond to the maximum amount of retained austenite, which falls with decreasing transformation temperature. The low values of both tensile strength and elongation in the initial stage of bainite transformation can be explained by premature fracture of tensile specimens and the tensile strength, hardness and elongation do not change considerably after a certain period. With a decreasing transformation temperature the tensile strength increase while the elongation decrease, especially the elongation has the maximum value at temperature $370^{\circ}C$.

A Theoretical Comparison of Two Possible Shape Memory Processes in Shape Memory Alloy Reinforced Metal Matrix Composite

  • Lee Jae Kon;Kim Gi Dae
    • Journal of Mechanical Science and Technology
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    • v.19 no.7
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    • pp.1460-1468
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    • 2005
  • Two possible shape memory processes, austenite to detwinned martensite transformation and twinned martensite to detwinned martensite transformation of a shape memory alloy have been modeled and examined. Eshelby's equivalent inclusion method with Mori-Tanaka's mean field theory is used for modeling of the shape memory processes of TiNi shape memory alloy reinforced aluminum matrix composite. The shape memory amount of shape memory alloy, plastic strain and residual stress in the matrix are computed and compared for the two processes. It is shown that the shape memory amount shows differences in a small prestrain region, but the plastic strain and the residual stress in the matrix show differences in the whole prestrain region. The shape memory process with initially martensitic state of the shape memory alloy would be favorable to the increase in the yield stress of the composite owing to the large compressive residual stress and plastic strain in the matrix.