• Title/Summary/Keyword: Asymmetry flow

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A Study on Asymmetry Design Represented in Modern Fashion (현대복식(現代服飾)에 나타난 비대칭(非對稱) 디자인 연구(硏究))

  • Choi, Kyung-Hee
    • Journal of Fashion Business
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    • v.5 no.3
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    • pp.129-143
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    • 2001
  • The purpose of this study is to pigeonhole theoretical notions of asymmetry and historical flow of asymmetry designed dresses, understand the trend of asymmetry design in modern fashion and find out its plastic character. The result of this study is as follows. The asymmetry is un-harmony artistic structure that unbalanced left and right in designing. The asymmetry fashion were seen that drapery dress of Egypt, Greece, Rome in ancient times and design by strong color contrast in heraldry and hose, accessory in the middle ages. In modern times, it was seen as complicated and mixed appearance by the influence of post-modernism. The asymmetry designs in modern fashion are shown varied styles by asymmetry of silhouette, detail, fabric, wearing method. The characters of these are a sense of de-construction, formative sense, and exaggeration The asymmetry design must be made by cutting, sewing, and high degree of technique through the latest skill and study.

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Localized Necking in a Round Tensile Bar for a HCP Material Considering Tension-compression Asymmetry in Plastic Flow (소성 비대칭성을 갖는 HCP 소재의 국부변형 및 네킹해석)

  • Yoon, J.H.;Lee, J.H.
    • Transactions of Materials Processing
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    • v.21 no.5
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    • pp.285-290
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    • 2012
  • In spite of progress in predicting ductile failure, the development of a macroscopic yield criterion to describe damage evolution in HCP (hexagonal close-packed) materials remains a challenge. HCP materials display strength differential effects (i.e., different behavior in tension versus compression) in their plastic response due to twinning. Cazacu and Stewart(2009) developed an analytical yield criterion for porous material containing randomly distributed spherical voids in an isotropic, incompressible matrix that shows tension-compression asymmetry. The goal of the calculations in this paper is to investigate the effect of the tension-compression asymmetry on necking induced by void nucleation, evolution and consolidation. In order to investigate the effect of the tension-compression asymmetry of the matrix on necking and fracture initiation, three isotropic materials A, B, and C were examined with different ratios of tension-compression asymmetry. The various types of material had BCC, FCC, and HCP crystal structures, respectively. The ratio between tension and compression in plastic flow significantly influences the fracture shape produced by damage propagation as well as affecting the localized neck.

Prediction of Asymmetric Turbulent Fluid Flow and Heat Transfer in the Parallel Plates (평행평판내 비대칭 난류유동과 열전달의 예측)

  • 오세경
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.3
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    • pp.303-310
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    • 1998
  • We report on the analytical results of examination of fully developed asymmetric flow and heat transfer between parallel plane plates. The asymmetry was introduced by roughening one of the plane while the other was left smooth. The integral method together with a turbulence model based on modified Prandtl's mixing length theory for the rough was used to determine the velocity distribution and friction. The temperature distrtibution is then predicted and heat transfer coefficients are calculated. The present paper shows that the heat transfer increases more than the friction factor for a given roughness structure. Generally the results show the strong effect of asymmetry on engineering parameters. Furthermore it is the roughness structure which influences the nature of asymmetry and heat transfer.

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Numerical Evaluation of Flow Nature at the Downstream of a Ball Valve Used for Gas Pipelines with Valve Opening Rates (개도율에 따른 가스파이프라인용 볼 밸브 후류유동의 수치평가)

  • KIM, CHUL-KYU;LEE, SANG-MOON;JANG, CHOON-MAN
    • Journal of Hydrogen and New Energy
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    • v.29 no.4
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    • pp.370-377
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    • 2018
  • Ball valve has been widely used in the field of high-pressure gas pipeline as an important component because of its low flow resistance and good leakage performance. The present paper focuses on the flow nature at the downstream of the ball valve used for gas pipelines according to valve opening rates. Steady 3-D RANS equations, SC/Tetra, have been introduced to analyze the flow characteristics inside the ball valve. Numerical boundary conditions at the inlet and outlet of the valve system are imposed by mass flow-rate and pressure, respectively. Velocity distributions obtained by numerical simulation are compared with respect to the valve opening rates of 30, 50, and 70%. Cavity distributions, asymmetry flow velocity and the flow stabilization point at each opening rate are also compared. When the valve opening rates are 30 and 50%, the flow stabilization requires the sufficient length of 10D or more due to the influence of the recirculation flow at the downstream of the valve.

Analysis of Influence for Breach Flow According to Asymmetry of Breach Cross-section (제방붕괴 형상의 비대칭성에 따른 붕괴흐름의 영향 분석)

  • Kim, Sooyoung;Choi, Seo-hye;Lee, Seung Oh
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.5
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    • pp.557-565
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    • 2016
  • The risk of collapse in hydraulic structures has become more elevated, due to the increased probability and scale of flooding caused by global warming and the resulting abnormal climatic conditions. When a levee, a typical hydraulic structure, breaks, an enormous breach flow pours into the floodplain and much flood damage then occurs. It is important to accurately calculate the breach discharge in order to predict this damage. In this study, the variation of the breach discharge with the asymmetry in the cross-section of the levee breach was analyzed. Through hydraulic experiments, the cross-section of the breach was analyzed during the collapse using the BASD (Bilateral ASymmetry Degree), which was developed to measure the degree of asymmetry. The relationship of the breach discharge was identified using the BASD. Additionally, the variation of the breach flow measured by the BASD was investigated through a 3-D numerical analysis under the same flow conditions as those in the experiment. It was found that the assumption of a rectangular breach cross-section, which is generally used for the estimation of the inundation area, can cause the breach discharge to be overestimated. According to the BASD, the breach flow is decreased by the interference effect in the breach section of the levee. If the breach flow is calculated while considering the BASD in the numerical analysis of the flooding, it is expected that the predicted inundation area can be estimated accurately.

Rotordynamic Forces Due to Rotor Sealing Gap in Turbines (비대칭 터빈 로터 실에 기인한 축 가진력)

  • Kim Woo June;Song Bum Ho;Song Seung Jin
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.545-548
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    • 2002
  • Turbines have been known to be particularly susceptible to flow-induced self-excited vibration. In such vibrations, direct damping and cross stiffness effects of aerodynamic forces determine rotordynamic stability. In axial turbines with eccentric shrouded rotors, the non-uniform sealing gap causes azimuthal non-uniformities in the seal gland pressure and the turbine torque which destabilize the rotor system. Previously, research efforts focused solely on either the seal flow or the unshrouded turbine passge flow. Recently, a model for flow in a turbine with a statically offset shrouded rotor has been developed and some stiffness predictions have been obtained. The model couples the seal flow to the passage flow and uses a small perturbation approach to determine nonaxiymmetric flow conditions. The model uses basic conservation laws. Input parameters include aerodynamic parameters (e.g. flow coefficient, reaction, and work coefficient); geometric parameters (e.g. sealing gap, depth of seal gland, seal pitch, annulus height); and a prescribed rotor offset. Thus, aerodynamic stiffness predictions have been obtained. However, aerodynamic damping (i.e. unsteady aerodynamic) effects caused by a whirling turbine has not yet been examined. Therefore, this paper presents a new unsteady model to predict the unsteady flow field due to a whirling shrouded rotor in turbines. From unsteady perturbations in velocity and pressure at various whirling frequencies, not only stiffness but also damping effects of aerodynamic forces can be obtained. Furthermore, relative contributions of seal gland pressure asymmetry and turbine torque asymmetry are presented.

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Numerical Investigation on Radiation Characteristics of Noise Propagating through Asymmetry Aero-Intake (비대칭 공기흡입구를 통해 전파하는 소음의 방사특성에 관한 수치적 연구)

  • Park, Yong-Hwan;Kim, Min-Woo;Lee, Kyu-Ho;Lee, Soo-Gab
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1476-1481
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    • 2007
  • Numerical investigation on radiation characteristics of discrete frequency noise from asymmetry aero-intakes was carried out. The near-field predictions were obtained by solving the linearized Euler equations with computational aeroacoustic techniques consisting of high order finite difference scheme, non-reflecting boundary conditions, oversetgrid techniques. For the prediction of far-field directivity pattern, the Kirchhoff integral method was applied. By comparing the directivities of noise radiating from the scarf and the scoop aero-intakes with that from an axisymmetric aero-intake, it is shown that noise reduction at downward peak radiation angle can be achieved. The scattering of the radiating acoustic wave by background mean flow shifts the peak lobe radiation angle toward ground and increases the amplitude of the acoustic pressure compared with the cases without mean flow effect.

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Quantitative Analysis of Regional Cerebral Blood Flow using $^{99m}Tc-HMPAO$ SPECT in Parkinson's Disease (파킨슨병에서 $^{99m}Tc-HMPAO$ SPECT를 이용한 국소뇌혈류의 정량적 분석)

  • Lee, Myung-Chul;Bae, Sang-Kyun;Lee, Myung-Hae;Chung, June-Key;Koh, Chang-Soon;Roh, Jae-Kyu;Myung, Ho-Jin
    • The Korean Journal of Nuclear Medicine
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    • v.26 no.2
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    • pp.251-256
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    • 1992
  • Regional cerebral blood flow were measured in 10 patients with Parkinson's disease and 12 normal persons using $^{99m}Tc-HMPAO$ SPECT. Reconstructed images were interpreted qualitatively and were compared with those findings of CT. For the quantitative analysis, six pairs of region of interest matched with the perfusion territories of large cerebral arteries and cerebellar hemisphere were determined. From the count values, indices showing the degree of asymmetry between right and left cerebral or cerebellar hemisphere, cerebral asymmetry index (ASI) and percent index of cerebellar asymmetry (PIA), and an index showing change of each region, region to cerebellum ratio (RCR) were obtained. ASI of normal persons and patients were $0.082{\pm}0.033$ and $0.108{\pm}0.062$, respectively and PIA were $-0.4{\pm}0.7%$ and $-0.7{\pm}1.0%$, respectively, which showed no statistically significant difference between normal persons and patients. Among 10 RCR's, those of both regions of basal ganglia and both regions of anterior cerebral artery were significantly reduced. We concluded that the most significant reduction of regional cerebral blood flow in patients with Parkinson's disease was observed in the regions of basal ganglia and in the regions of anterior cerebral artery, and the degree of change in hemispheric blood flow was similar in both hemisphere.

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