• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1229-1239
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• 1999

A computational study on unsteady compressible flows has been performed by adopting a low Reynolds number $k-{\omega}$ turbulence model in conjunction with dual time stepping scheme. An explicit four-stage Runge-Kutta scheme for the Navier-Stokes equations and an approximate factorization scheme for the $k-{\omega}$ turbulence model equations are used. Computational results obtained for blade surface pressure distributions in the process of rotor-stator interaction in a turbine stage are in good agreement with extant experimental data. The effects of the wake from the stator on the boundary-layer transition over the rotor blade surface are discussed by showing that high intensity turbulence of the stator wake induces an early transition.

• Journal of Ocean Engineering and Technology
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• v.30 no.2
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• pp.125-133
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• 2016

In this paper, we propose a vertical axis water turbine with dual blades. A parametric study was conducted using numerical analyses. First, a two-dimensional finite-volume analysis with a commercial code was used to find the pitch angle of the main blade under different tip speed ratio conditions. Second, we developed a potential-based panel method to find the best configuration of the inner blades. Experimental tests were conducted at the circulating water channel of Chungnam National University. Various configurations of the dual blades were considered, and their performances were comparatively investigated. The results showed that the turbine with movable dual blades produces a constant torque and tip speed ratio at various flow rates.

• Korean Institute of Interior Design Journal
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• v.24 no.1
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• pp.93-103
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• 2015

This study set out to figure out the tendencies of the staff members participating in the space design of Blade Runner and compare and analyze its set and location characteristics with its narrative based on Gilles Deleuze' Simulacrum, one of the basic theories of Post modernism, thus identifying the characteristics of postmodern space inherent in it. The findings were as follows: first, the spaces in a Late modernism tendency in Blade Runner seem to have been created by the cinematic imagination of Syd Mead and Douglas Trumbull rather than being influenced by the old Late modernism architecture. Second, the postmodern spaces of the movie were designed to depict a more realistic future by reinforcing the old ornamental elements or adding the mechanical aesthetics of Late modernism based on a prediction of future cities. Third, the characters representing Late modernism and Post modernism in the narrative of the movie embrace the tendencies of the parties objected by Model and Simulacrum in the scenes where they deny the tendencies of the spaces to which they belong, thus exhibiting a dual trend. Fourth, the dual narrative of Model and Simulacrum holds duality even in the space and architecture of the movie, which is the reason why the movie chose postmodern spaces reflecting historical contexts instead of inner spaces in the tendency of minimalism, which was in vogue when SF movies were made those days. Finally, the spaces of the movie can be categorized according to the Late modernism and Post modernism tendencies from the perspective of the 1980s and be understood to show the architecture and space of future Post modernism feasible through the layering of historicity, locality, and mechanical aesthetics from ancient Maya to a future city in Los Angeles, the background of the movie, from the perspective of 2019.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.667-668
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• 2012

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.1
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• pp.15-21
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• 2006

Parametric cycle analysis of a dual-spool, mixed exhaust turbofan engine with turbine blade cooling were described to investigate the effect of turbine blade cooling on the engine performance such as specific thrust and thrust specific fuel consumption. Coolant of low pressure turbine triggers high engine performance loss and cooling effect loss in high pressure turbine. Therefore low pressure turbine coolant should be much more considered for effective design.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1684-1689
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• 2003

This paper concerns the analytical modeling and dynamic analysis of advanced cantilevered blade structure implemented by a dual approach based on structural tailoring and viscoelastic materials technology. Whereas structural tailoring uses the directionality properties of advanced composite materials, the passive materials technology exploits the damping capabilities of viscoelastic material(VEM) embedded into the host structure. The structure is modeled as a composite thin-walled beam incorporating a number of nonclassical features such as transverse shear, secondary warping, anisotropy of constituent materials, and rotary inertias. The case of VEM spreaded over the entire span of the structure is considered. The displayed numerical results provide a comprehensive picture of the synergisitic implications of the application of both techniques, namely, the tailoring and damping technology on vibration response of thin-walled beam structure exposed to external time-dependent excitations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1087-1094
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• 2012

This study deals with structural analysis and testing under loading conditions calculated by computational fluid dynamics for a small composite blade that is utilized in a dual rotor wind turbine system. First, the aerodynamic forces were analyzed at the rated and cutout wind speed to identify the bending moment distribution along the blade length in previous research. Then, full-scale structural tests were conducted according to IEC 61400-2 to evaluate the structural integrity of the composite blade. These results were compared with finite element analysis to identify the accuracy of the structural analysis. Based on these results, it was revealed that the existing blade has a very high safety margin. Then, the layup of the composite blade was redesigned and analyzed using finite element analysis to achieve structural integrity and economic efficiency.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.7
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• pp.40-50
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• 2005

In this paper, preliminary results for performance prediction of a dual-rotor wind turbine generator system are presented. Blade element and momentum theories are used to model the aerodynamic forces and moments acting on the rotor blades, and multi-body dynamics approach is used to integrate the major components to represent the overall system. Not only the steady-state performance but the transient response characteristics are analyzed. Pitch control strategy to control the rotor speed and the generator output is proposed and its performance is verified through the nonlinear simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.5
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• pp.381-390
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• 2016

In this study, aeroacoustic characteristics of combined fan are investigated and noise was reduced by applying Serrated Trailing Edge which is known as the method to reduce fan noises. Unsteady CFD (Computational Fluid Dynamics) analysis was carried out using Lattice Boltzmann Method(LBM) to figure out the combined fan's aeroacoustics and experimental results was used to verify simulation results. Results show that different BPFs are generated at the each inner fan and outer fan on the different frequency while Blade Passing Frequency(BPF) of general fans is constant on the entire frequency range. Boundary vortex and vortex shedding are suppressed or dispersed by applying the Serrated Trailing Edge to the inner fan. Furthermore, broadband noise and fan's torque are reduced.

• Journal of Mechanical Science and Technology
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• v.20 no.8
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• pp.1139-1148
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• 2006

This paper addresses the analytical modeling and dynamic response of the advanced composite rotating blade modeled as thin-walled beams and incorporating viscoelastic material. The blade model incorporates non-classical features such as anisotropy, transverse shear, rotary inertia and includes the centrifugal and coriolis force fields. The dual technology including structural tailoring and passive damping technology is implemented in order to enhance the vibrational characteristics of the blade. Whereas structural tailoring methodology uses the directionality properties of advanced composite materials, the passive material technology exploits the damping capabilities of viscoelastic material (VEM) embedded into the host structure. The VEM layer damping treatment is modeled by using the Golla-Hughes-McTavish (GHM) method, which is employed to account for the frequency-dependent characteristics of the VEM. The case of VEM spread over the entire span of the structure is considered. The displayed numerical results provide a comprehensive picture of the synergistic implications of both techniques, namely, the tailoring and damping technology on the dynamic response of a rotating thin-walled b ε am exposed to external time-dependent excitations.