• Title/Summary/Keyword: OFO

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A Study on China's Intention to Switching to Shared Bike Platforms: Mechanisms of Trust and Distrust

  • Wenlong Lu;Yung Ho Suh;Sae Bom Lee
    • Journal of the Korea Society of Computer and Information
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    • v.28 no.7
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    • pp.179-187
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    • 2023
  • Consumer trust plays a crucial role in the development of the sharing economy. This study primarily focuses on the factors influencing consumer trust and examines the case of ofo, a former leader in China's bike-sharing industry. This paper analyzes the decline in consumer trust in ofo, which can be attributed to internal management issues and the near-bankruptcy situation. The "difficulty in refunds" issue faced by ofo since December 2018 has been growing continuously, and this study explores the factors influencing trust and distrust in this context. By considering product factors (quality), platform factors (payment security, privacy protection, reputation), and social factors (social norms, government regulation) as independent variables, the study analyzes the factors affecting consumer trust. The analysis results revealed that as consumers' distrust towards shared bikes increases, their switching intention also increases. The company's reputation and social norms were found to influence both trust and distrust, while government regulation was found to influence trust. The research findings provide insights relevant to sharing economy platforms and offer guidance for future studies.

Analysis of Spray Combustion for the Performance Prediction of Liquid Rocket Combustor (3차원 분무연소장 해석에 의한 액체추진기관 연소실 성능예측에 대한 연구)

  • 황용석;윤웅섭
    • Journal of the Korean Society of Propulsion Engineers
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    • v.3 no.3
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    • pp.31-39
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    • 1999
  • In this paper, numerical experiment is attempted to analyze and compare the combustion efficiency of the burning sprays due to OFO, FOF triplet / FOOF split doublet injectors. Preconditioned Wavier-Stokes equation system with low Reynolds number $\kappa$-$\varepsilon$ model for turbulence closure, is LU-SGS time-integrated. Spray processes are modeled by DSF analysis with experimentally determined injection characteristics. n-heptane/air global reaction model approximates the combustion for simplicity, and the influence of turbulence on the chemical reaction is included using eddy dissipation model. The results showed the FOF triplet injector of highest combustion efficiency, whereas the OFO type of poet performance. It was also observed that the droplet mean diameter and the average gas temperature due to the mixing efficiency, are the representative parameters for the performance design of combustion.

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The Comparison of Spray Characteristics between FOOF and FOF Injectors used in Liquid Rockets (액체로켓용 FOOF와 FOF 인젝터의 분무특성 비교)

  • 임병직;정기훈;윤영빈
    • Journal of the Korean Society of Propulsion Engineers
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    • v.7 no.2
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    • pp.1-6
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    • 2003
  • Triplet(FOF or OFO) injectors are commonly applied to liquid rockets which use LOX and hydrocarbon propellants. The FOF type injector has been known to have an advantage for the although to show lower combustion performance as compared by the OFO type. However, a large disparity between oxidizer and fuel orifice diameters of the FOF type injector may reduce both the combustion efficiency and stability so that as FOOF split triplet injector which splits a single oxidizer orifice into double orifices was designed. In the present study, spray characteristics of the FOOF injector were investigated and compared with those of the FOF injector undo. cold flow conditions. Mass distributions of oxidizer and fuel for both injectors were measured by using a PLLIF (Planar Liquid Laser Induced Fluorescence)technique, and each drop size was also measured by using an instantaneous photographic method. From the experimental results, we found out that FOOF shows more stable mixing efficiencies than the FOF. As for the drop size of both oxidizer and fuel, there was not a large difference between two injector types.

Turbulent Spray Combustion due to Triplet/Split Doublet Injectors (삼중/분리 충돌형 분사특성에 따른 난류 분무연소장 해석)

  • Hwang Yong-Sok;Yoon Woong-Sup
    • 한국전산유체공학회:학술대회논문집
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    • 1998.11a
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    • pp.211-219
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    • 1998
  • Propellants pressurized and fed into the combustion chamber undergoes the mechanical, chemical combustion processes. Along with their distinctive physical characteristics, propellant combustion is typically divided into the processes; injection, atomization, mixing, vaporization and chemical reaction. These processes assumed to happen in a serial manner are strongly coupled, thereby involves formidable physical complexities. In this study a numerical experiment is attempted to simulate the burning sprays due to OFO, FOF triplet / FOOF split doublet injectors. Based on Eulerian-Lagrangian frame, Navier-Stokes equation system for compressible flows is preconditioned with low Reynolds number $k-{\varepsilon}$ turbulent model and time-integrated by LU-SGS, and the sprays are described by DSF model with the characteristics initialized by experimentally determined spray characteristics. Simplified single global reaction model approximates heptane-air reaction. It was observed that FOOF split doublet injector shows better atmization with shortest residence and the FOF triplet injector produces better combustion performance.

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