• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.732-739
• /
• 2005

The determination of sound pressure radiated from periodic plate structures is fundamental in the estimation of noise level in aircraft fuselages or ship hull structures. As a robust approach to this problem, here a very general and comprehensive analytical model is developed for predicting the sound radiated by a vibrating plate stiffened by periodically spaced orthogonal symmetrical beams subjected to a sinusoidally time varying point load. In this these, we experiment with the numerical analysis using the space harmonic series and the SYSNOISE for measuring the vibration mode and character of response caused by sound radiation with adding the harmonic point force in the thin isotropic plate supported by the rectangular lattice reinforcement. We used the reinforcements, beams of open type section like the style of 'ㄷ' letter; the space of the beams were chosen to be 0.2m, 0.3m, 0.4m. We studied the behavior of sound pressure levels, analysis of vibration mode between support points, connection between frequency function and sound pressure levels, and connection between position function and sound pressure levels.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.60 no.4
• /
• pp.181-185
• /
• 2011

Due to the increasing of nonlinear loads such as converters and inverters connected to the electric power distribution system, and extensive application of harmonic generation sources with power electronic devices, disturbance of the electric power system and its influences on industries have been continuously increasing. Thus, it is difficult to construct accurate load model for active and reactive power in environments with harmonics. In this research, we develop current harmonics estimation method based on Extreme Learning Machine (ELM) with fast learning procedure for residential loads. Using data sets acquired from various residential loads, the proposed method has been intensively tested. As the experimental results, we confirm that the proposed method makes it possible to effective estimate current harmonics for various input voltage.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.12
• /
• pp.2370-2378
• /
• 2009

The enhanced phase angle estimation algorithm is essential to supply the power stably under synchronizing with grid source. In this paper, we are proposed the novel phase angle estimation algorithm and verified the validity of proposed method as simulation with PSIM and experiments. We sort the harmonics element using high-pass filter(HPF) that have the cut-off frequency below basic element and make reverse d-q transformation. So, it can be restored the harmonics element at stationary axis, and we can get the fundamental voltage element of AC grid. Proposed PLL method have a rapid responsibility and a large margin at controller design than conventional method because it have a small phase delay and a sufficient controller gain margin. And, it can reduce the error of voltage rms value and axis transformation according to robust PLL algorithm against the harmonic and phase unbalance.

• Journal of Biomedical Engineering Research
• /
• v.9 no.1
• /
• pp.101-108
• /
• 1988

In this paper the power spectrum of background EEG is estimated by the LMS PHD based on least mean square. At the power spectrum estimatiom, the stocastic process of background EEG is assumed to consist of the nonharmonic sinusoid and the white noise. In the LMS PHD the model parameters are obtained by the least mean square at optimal order which is obtained from the fact that the eigenvalue's fluctuation of autocorrelation matrix of the normal back-ground EEG is smaller at some order than at other order when the power spectrum of background EEG is esitmated by PHD. The optimal order of this model is the 6-th order when the eigenvalue's fluctuation of autocorrelation matrix of background EEG is considered. The estimation results are with compared the results from the Maximum Entropy Spectral Estimation and Pisarenko Harmonic Decomposition. From the comparison results. The LMS PHD is possible to estimate the power spectrum of background EEG.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.9
• /
• pp.1269-1274
• /
• 2012

In this paper, the iron loss was calculated using estimated iron loss coefficient at 650W Interior Permanent Magnet Synchronous Motor(IPMSM) and 250W IPMSM. The iron loss coefficients was estimated different according to electrical steel material used to stator and rotor core in motor. Aspect of The rotating flux field and alternating flux field was confirmed by magnetic field behavior and harmonic analysis in stator core, the iron loss was calculated using flux density by Finite Element Method(FEM) and estimated coefficients by iron loss coefficient estimation proposed in this paper. The iron loss experiment was performed for verified to iron loss calculation, and the iron loss coefficients were verified by comparison of iron loss calculation value and experimental value.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.4
• /
• pp.294-297
• /
• 2021

A grid voltage estimation method for modular plug-in active power decoupling (APD) circuits is proposed in this study as direct replacements of electrolytic capacitors. Since modular plug-in APD circuits cannot have additional grid voltage sensors and should be operated independently without information exchange with the front-end converter, it is impossible to obtain the phase information of the grid directly. Therefore, the proposed method uses the second-order harmonic component of the DC-link voltage to estimate the grid voltage necessary to control the APD circuit. By employing the proposed method, the concept of modular plug-in APD circuits can be realized and implemented without direct detection of the grid voltage. The experimental results based on hardware-in-the-loop simulation (HILS) validate the effectiveness of the proposed control method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.263-268
• /
• 2000

In this paper, a new indirect feedback active noise control (ANC) scheme based on the fundamental frequency estimation is proposed for systems with a harmonic noise. When reference signals necessary for feedforward ANC configuration is difficult to obtain, the conventional ANC algorithms for multi-tonal noise do not measure the reference signals but generate them with the estimated frequencies. However, the beating phenomena, in which certain frequency components of the noise vanish intermittently, may make the adaptive frequency estimation difficult. The confusion in the estimated frequencies due to the beating phenomena makes the generated reference signals worthless. The proposed algorithm consists of two parts. The first part is a reference generator using the fundamental frequency estimation and the second one is the conventional feedforward control. We propose the fundamental frequency estimation algorithm using decision rules, which is insensitive to the beating phenomena. In addition, the proposed fundamental frequency estimation algorithm has good tracking capability and lower variance of frequency estimation error than that of the conventional cascade ANF method. We are also able to control all interested modes of the noise, even which cannot be estimated by the conventional frequency estimation method because of the poor SIN ratio. We verify the performance of the proposed ANC method through simulations for the measured cabin noise of a passenger ship and the measured time-varying engine booming noise of a passenger vehicle.

• Journal of KSNVE
• /
• v.10 no.6
• /
• pp.1059-1066
• /
• 2000

In this paper. a new indirect feedback active noise control (ANC) scheme barred on the fundamental frequency estimation is proposed for systems with a harmonic noise. When reference signals necessary for feedforward ANC configuration are difficult to obtain, the conventional ANC algorithms for multi-tonal noise do not measure the reference signals but generate them with the estimated frequencies.$^{(4)}$ However, the beating phenomena, in which certain frequency components of the noise vanish intermittently, may make the adaptive frequency estimation difficult. The confusion in the estimated frequencies due to the beating phenomena makes the generated reference signals worthless. The proposed algorithm consists of two parts. The first part is a reference generator using the fundamental frequency estimation and the second one is the conventional feedforward control. We propose the fundamental frequency estimation algorithm using decision rules. which is insensitive to the beating phenomena. In addition, the proposed fundamental frequency estimation algorithm has good tracking capability and lower variance of frequency estimation error than that of the conventional cascade ANF method.$^{(4)}$ We are also able to control all interested modes of the noise, even which cannot be estimated by the conventional frequency estimation method because of the poor S/N ratio. We verify the performance of the proposed ANC method through simulations for the measured cabin noise of a passenger ship and the measured time-varying engine booming noise of a passenger vehicle.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.6
• /
• pp.1345-1351
• /
• 2013

Variable iron loss as function of current phase angle of Interior Permanent Magnet Synchronous Motor(IPMSM) was calculated through Curve Fitting Method(CFM). Also, a magnetic flux density distribution of iron core according to current phase angle was analyzed, and an iron loss calculation was performed including harmonic distortion. The experiment was performed by production of non-magnetizing model for the separation of mechanical loss, and the iron loss was calculated by the measurement of input using power analyzer and output power using dynamometer. Some error was generated between experimental results and calculation value, but an iron loss diminution according to current phase angle followed a same pattern. So, errors were generated by measurement, vibration, noise, harmonic distortion loss, etc.

• Journal of the Korean Mathematical Society
• /
• v.37 no.1
• /
• pp.31-44
• /
• 2000

We study a free boundary problem satisfying Bernoulli type boundary condition along which the gradient of a piecewise harmonic solution jumps zero to a given constant value. In such problem, the free boundary splits the domain into two regions, the zero set and the harmonic region. Our main interest is to identify the global shape and the location of the zero set. In this paper, we find the lower and the upper bound of the zero set. In a convex domain, easier estimation of the upper bound and faster disk test technique are given to find a rough shape of the zero set. Also a simple proof on the convexity of zero set is given for a connected zero set in a convex domain.