• Title/Summary/Keyword: 비정상흐름장

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Numerical Analysis of the Turbine Rotor Flow with the Unsteady Passing Wake from a Stator (정익에서 발생한 비정상 후류를 지나는 터빈 동익 유동장 수치해석)

  • Lee, Eun-Seok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.4
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    • pp.275-280
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    • 2007
  • A turbine stage consists of stators and rotors. The stator provides the required inlet flow conditions so that the rotor can produce the necessary power. Passing wakes generated from the trailing edge of the stator make an interaction with the rotor. In the present study, this flow mechanism is investigated using the numerical analysis. In case of a large gap distance between the stator and rotor, the flow can be solved independently. First, only the stator flow field is solved. Second, the rotor flow field is solved including the passing wake characteristics obtained from the stator analysis. The passing wake experiences the shearing as it approaches to the rotor blade leading edge. And it is chopped when it strikes the rotor blade. After that, the chopped wakes becomes the prolongation as it travels downstream. The flow according to the variation of the gap distance is also studied. Pressure jumps due to the passing wakes result in the pressure and lift loss and it gets stronger with the closer gap distance.

A Study about Internal Control Deficient Company Forecasting and Characteristics - Based on listed and unlisted companies - (내부통제 취약기업 예측과 특성에 관한 연구 - 상장기업군과 비상장기업군 중심으로 -)

  • Yoo, Kil-Hyun;Kim, Dae-Lyong
    • Journal of Digital Convergence
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    • v.15 no.2
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    • pp.121-133
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    • 2017
  • The propose of study is to examine the characteristics of companies with high possibility to form an internal control weakness using forecasting model. This study use the actual listed/unlisted companies' data from K_financial institution. The first conclusion is that discriminant model is more valid than logit model to predict internal control weak companies. A discriminant model for predicting the vulnerability of internal control has high classification accuracy and has low the Type II error that is incorrectly classifying vulnerable companies to normal companies. The second conclusion is that the characteristic of weak internal control companies have a low credit rating, low asset soundness assessment, high delinquency rates, lower operating cash flow, high debt ratios, and minus operating profit to the net sales ratio. As not only a case of listed companies but unlisted companies which did not occur in previous studies are extended in this study, research results including the forecasting model can be used as a predictive tool of financial institutions predicting companies with high potential internal control weakness to prevent asset losses.