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SOLUTIONS OF A CLASS OF COUPLED SYSTEMS OF FUZZY DELAY DIFFERENTIAL EQUATIONS

  • Wu, Yu-ting;Lan, Heng-you;Zhang, Fan
    • Nonlinear Functional Analysis and Applications
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    • v.26 no.3
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    • pp.513-530
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    • 2021

  • The purpose of this paper is to introduce and study a class of coupled systems of fuzzy delay differential equations involving fuzzy initial values and fuzzy source functions of triangular type. We assume that these initial values and source functions are triangular fuzzy functions and define solutions of the coupled systems as a triangular fuzzy function matrix consisting of real functional matrices. The method of triangular fuzzy function, fractional steps and fuzzy terms separation are used to solve the problems. Furthermore, we prove existence and uniqueness of solution for the considered systems, and then a solution algorithm is proposed. Finally, we present an example to illustrate our main results and give some work that can be done later.

  • https://doi.org/10.22771/nfaa.2021.26.03.05 인용 PDF KSCI

FORMULATION OF NEAR AND FAR ACOUSTIC FIELD FROM AN INCOMPRESSIBLE FLOW FLRCTUATION AROUND THE RIGID WALL

  • Ryu, Ki-Wahn;Lee, Duck-Joo
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1996.06a
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    • pp.59-62
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    • 1996

  • A numerical study of a two-dimensional acoustic field is carride ort for a spinning vortex pair located neat a wall to investigate the effect of the wall from the spinning quadrupole source in unsteady vortical flows. Based on the known incompressible flow field, the perturbed compressible acoustic terms derived from the Euler equations are calculated. Non-reflecting boundary conditions on the free field and the solid boundary conditions are developed for a generalized curvilinear coordinates system to investigate the effect of a curced wall. It is concluded that the sound generated by the quadrupole sources of unsteady vortical flows in the presence of a flat wall or a circular cylinder can be calculated by using the source terms of hydrodynamic flow fluctuations in both near and far acoustic fields simultaneously.

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A Study on Color Reproduction and Flatness of the LED Light Source in Broadcasting Lighting (방송조명에서 LED광원의 색 재현성과 평탄도 연구)

  • Kim, Young-Jin;Park, Gooman
    • Journal of Broadcast Engineering
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    • v.21 no.4
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    • pp.538-551
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    • 2016

  • At the on-site of broadcasting production, the light source of tungsten halogen has been used as a primary light source for representing video images. Although tungsten halogen light has drawn attention in terms of the color reproducibility which is more similar to the sun light than that of other light sources, meanwhile it had problems in energy efficiency. Recently, the LED light source with high efficiency and long lifetime of the energy source has started getting attention as a substitute light source at the broadcast field. Because of the unique light emission principles, compared with tungsten halogen, LED light source has different characteristics in the quality of the light projected from the light source and color reproduction of the video image through a camera. These characteristics cause the delayed introduction of the LED as the broadcast light source. In this study we measured the quality characteristics of the flatness of the color reproduction and light of the LED light source and will present the experimental data whether it is suitable as the broadcasting light source compared to a reference light source of tungsten halogen. In addition, we suggested the future challenges and standards which are needed to expand usage of LED as a broadcast light source.

  • https://doi.org/10.5909/JBE.2016.21.4.538 인용 PDF KSCI KPUBS HTML

Combining CFD/FEM/BEM/SEA to Predict Interior Vehicle Wind Noise - Validation Case CAA German Working Group (자동차 유동기인 실내소음 예측을 위한 CFD/FEM/BEM/SEA 의 조합 및 검증 - CAA German Working Group)

  • Blanchet, D.;Golota, A.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.800-811
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    • 2014

  • Recent developments in the prediction of the contribution of windnoise to the interior SPL have opened a realm of new possibilities in terms of i) how the convective and acoustic sources terms can be identified, ii) how the interaction between the source terms and the side glass can be described and finally iii) how the transfer path from the sources to the interior of the vehicle can be modelled. This work discusses in details these three aspects of wind noise simulation and recommends appropriate methods to deliver required results at the right time based on i) simulation and experimental data availability, ii) design stage at which a decision must be made and iii) time available to deliver these results. Several simulation methods are used to represent the physical phenomena involved such as CFD, FEM, BEM, FE/SEA Coupled and SEA. Furthermore, a 1D and 2D wavenumber transformation is used to extract key parameters such as the convective and the acoustic component of the turbulent flow from CFD and/or experimental data whenever available. This work focuses on the validation of the wind noise source characterization method and the vibro-acoustic models on which the wind noise sources are applied.

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Combining CFD/FEM/BEM/SEA to Predict Interior Vehicle Wind Noise - Validation Case Hyundai BMT4 (자동차 유동기인 실내소음 예측을 위한 CFD/FEM/BEM/SEA 의 조합 및 검증 - 현대자동차 BMT4)

  • Blanchet, D.;Golota, A.;Almenar, R.;Lim, J.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.563-564
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    • 2014

  • Recent developments in the prediction of the contribution of windnoise to the interior SPL have opened a realm of new possibilities in terms of i) how the convective and acoustic sources terms can be identified, ii) how the interaction between the source terms and the side glass can be described and finally iii) how the transfer path from the sources to the interior of the vehicle can be modelled. This work discusses several simulation methods that can be used to represent the physical phenomena involved such as CFD, FEM, BEM, FE/SEA Coupled and SEA. This work focuses on the validation of the wind noise source characterization method and the vibro-acoustic models on which the wind noise sources are applied in the framework of a benchmark proposed by Hyundai Motors Corporation.

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