• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2031-2036
• /
• 2011

To leading subway technology Advanced Urban Transit System is developed by national research and development. Next-generation trains equipped with direct driving permanent magnet traction motor and individually controlled propulsion system. Electromagnetic properties of the Next-Generation Train from four perspectives will be discussed. The first is closely related to human hazards that affect the 60Hz low frequency electromagnetic field. The Second is inductive noise that affect railroad signal system. The third is conductive noise that affect communication line near railroad. The 4th is radiation noise that may affect electronic equipment near the railroad tracks.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.6
• /
• pp.717-725
• /
• 2004

A power generation systems are proposed to convert ambient mechanical vibration into electrical energy using cantilever-type piezoelectric materials. The vibration-based power device can be used for self-powered systems without batteries. This paper presents the theoretical analysis for the coupled equations of piezoelectric and structural motions and investigates the dynamic characteristics of the self-power system using transfer function method. The theoretical model is verified by the finite element analysis of the resonance frequency, the dynamic response of the structure and the sensor sensibility. Experimental results measured using a prototype system agree with the theoretical predictions. The system is shown to produce 34.5 ㎼ in average. Finally, we perform the optimal design for system variables to maximize output power.

• Proceedings of the KIEE Conference
• /
• 1990.11a
• /
• pp.45-48
• /
• 1990

This paper deals with the control strategy for constant voltage, constant frequency (CVCF) generation of doubly-fed Induction generator. As induction machine is a nonlinear and multivariable machine, so, the influential factors for CVCF generation of induction generator are the magnitude of output voltage, load current and its power factor, slip of the machine, etc. To get appropriate control scheme and to research the effect of its parameters, the control equation of induction machine is derived and tested. The derived condition is very useful for the CVCF control of the machine and for determing the characteristics of the system. The simulation results show that magnetizing reactance and rotor resistance is a very important parameter in this control system.

• 한국연소학회:학술대회논문집
• /
• 2004.06a
• /
• pp.27-33
• /
• 2004

The Noise generation mechanisms of propane laminar premixed flames on a slot burner have been studied experimentally. The sound levels and frequencies were measured for various mixture flow rates (velocities) and equivalence ratios. The primary frequency of self-induced noise increases with the mean velocity of mixture as $f{\;}{\propto}{\;}U_f^{1.144}$ and the measured noise level increases with the mixture flow rate and equivalence ratio as $p{\;}{\propto}{\;}U_f^{1.7}$$F^{8.2}$. The nature of flame oscillation and the noise generation mechanisms are also investigated using a high speed CCD camera and a DSRL camera. The repetition of sudden extinction at the tip of flame is evident and the repetition rates are identical to the primary frequencies obtained from the FFT analysis of sound pressure signals. CH chemiluminescence intensities of the oscillating flames were also measured by PMT with a 431 nm(10 FWHM) band pass filter and compared to the pressure signals.

• Proceedings of the KIEE Conference
• /
• 1999.07c
• /
• pp.1070-1072
• /
• 1999

Automatic Generation Control(AGC) is a control system whose objectives are to hold system frequency close to a specified nominal value and to maintain each unit's generation at the most economic value. It has been used to control the output of a generator by the control signal of the generator, but it is not appropriate to apply to generators which adopt the distributed control system. In this paper a method for improving the AGC operation is proposed, and the different response of each generator and various types of control systems of generators are considered. The interface among Remote Terminal Detector(RTU) and control systems and the direct delivery of the data between EMS and DCS also are proposed in the paper.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.291-293
• /
• 2003

This paper deals with a thrust generation of flapping-airfoil by dynamic stall. From many other previous research results, phase angle $ between pitching and plunging mode of flapping motion must be 90 deg. to satisfy maximum propulsive efficiency. In this case, leading edge vortex is relatively small. This phenomenon is related dynamic stall. So preventing leading edge vortex induced by dynamic stall guarantees maximum propulsive efficiency. But, in this paper we insist the leading edge vortex yields quite a positive influence on thrust generation and propulsive efficiency. In order to certify our opinion, pitching and plunging motions were calculated with the parameter of amplitude and frequency by using the unsteady, incompressible Navier-Stokes flow solver with a two-equation turbulence model. For more efficient computation, it is parallelized by MPI programming method.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.11 no.4
• /
• pp.31-36
• /
• 2001

A spin coater is a machine to coat wafer or LCD display with thin film. Vibration in the spin coater may be one of main troubles in the coating process. In this paper, we focus on the difference between two spin coaters. Vibration sources are identified by experimental approach and are compared to find the difference between the two spin coaters. Also, the particle concentration is observed by laser particle counter (LPC) for the two spin coaters, when the spin coaxers are working. It is also considered whether the defect rate is proportional to the particle concentration. The result shows that particle generation in the coating process is related to excessive vibration of the spin coater shaft and the particles influence the defect rate of the thin film product.

• Proceedings of the KIPE Conference
• /
• 2003.11a
• /
• pp.99-103
• /
• 2003

Recently, a fuel cell with low voltage and high current of electronic output characteristics is remarkable for new generation system. It needs both a dc-dc boost converter and do-ac inverter to be used in domestic power. Therefore, this paper presents do-dc boost converter with ZVS for fuel cell generation system This topology has several advantages, which are ZVS characteristics of all of main and auxiliary switches, reduction of reactor component size because of high frequency switching, and low rated voltage stress of the switches. In this paper, theoretical analysis, operation principle, and design procedures are presented. And simulation results from Pspice are presented to validate the theoretical analysis.

• Journal of Power Electronics
• /
• v.16 no.2
• /
• pp.748-759
• /
• 2016

The microgrid concept is a promising approach for injecting clean, renewable, and reliable electricity into power systems. It can operate in both the grid-connected and the islanding mode. This paper addresses the two main challenges associated with the operation of a microgrid i.e. control and protection. A control strategy for inverter based distributed generation (DG) and an energy storage system (ESS) are proposed to control both the voltage and frequency during islanding operation. The protection scheme is proposed to protect the lines, DG and ESS. Further, the control scheme and the protection scheme are coordinated to avoid nuisance tripping of the DG, ESS and loads. The feasibility of the proposed method is verified by simulation and experimental results.

• Proceedings of the KIEE Conference
• /
• 2002.11b
• /
• pp.59-61
• /
• 2002

This paper describes how travelling waves measured at an end of a transmission line can be used for fault location. In this paper a FIR filter which makes' high frequency components much more prominent is proposed. Consequently. the algorithm can distinguishes correlation peaks. A series of simulation studies using EMTP verified that the proposed algorithm can calculate an accurate fault distance in spite of effects of various errors.