김동현 교수

The flow-field around the rotor blades of an FOWT may be significantly influenced by the six rigid-body motions of the floating platform via the blade–wake interaction. Therefore, the accurate prediction of unsteady aerodynamic load which is calculated by many conventional numerical approaches is still questionable for an FOWT. In this study, the periodic pitching motion of the rotating turbine blades due to the floating platform motion is considered to investigate the effects of vortex–wake–bla

The objective of this study is to illustrate the unsteady aerodynamic effects of a floating offshore wind turbine experiencing the prescribed pitching motion of a supporting floating platform as a sine function. The three-dimensional, unsteady Reynolds Averaged Navier-Stokes equations with the shear-stress transport (SST) k-ω turbulence model were applied. Moreover, an overset grid approach was used to model the rigid body motion of a wind turbine blade. The current simulation results are compar

Nonlinear aeroelastic computations are presented for a sweptback wing with underpylon/finned-store in the transonic and supersonic flow regions, where strong shock wave interactions exist. A modal-based coupled nonlinear aeroelastic analysis system with the matched-point concept has been developed using the high-speed parallel processing technique. Advanced numerical techniques such as computational structural dynamics and computational fluid dynamics are used. It is expected to provide accurate

This work was basically supported by the National Research Laboratory (NRL) program of Korea Ministry of Science and Technology, and also by the research project with Korea Aerospace Industry. The authors would like to acknowledge the supports.

We have developed new band to band tunneling (BTBT) model, which captures band structure information, all possible transitions between different valleys, energy quantization and quantized density of states (DOS). Minimum standby off-state currents (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF,MIN</sub> ) are investigated in double gate (DG) MOSFETs with various high mobility materials, like GaAs, InAs, Ge and strained Si/Ge (s-Si/s-Ge) usin

A 135 GHz <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Gm</i> -boosted down-conversion active mixer adopting dual baluns has been developed in this work. Fabricated with a 0.18- μm SiGe BiCMOS technology, the mixer exhibits a differential-mode conversion gain of 11.5 dB at RF frequency of 134.7 GHz for a fixed LO frequency and power of 134 GHz and 10 dBm, respectively. The mixer also shows a <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:x

This paper provides the analysis and comparison of carrier-based PWM methods for 3-level inverter. Up to now, there were few papers dealing with harmonic characteristics of various modulation indexes in the 3-level inverter. Therefore, the PWM methods for the 3-level inverter need be analyzed and compared. The current harmonics of a 3-level inverter is compared with those of conventional 2-level inverter by the analysis of harmonic voltage vector, and the harmonic currents for various modulators