• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 한국전산구조공학회 1996년도 봄 학술발표회 논문집
• /
• pp.119-126
• /
• 1996

In this paper, a method of substructural identification is presented for the estimation of localized structural parameters. for this purpose, an auto-regressive and moving average with stochastic input (ARMAX) model is derived for the substructure to process the measurement data impaired by noises. The sequential prediction error method is used fer the estimation of unknown localized parameters. Using the substructural method, the number of unknown parameters can be reduced and the convergence and accuracy of estimation can be improved. For some substructures, the effect of the input excitation is expressed in terms of the responses at the inferences with the main structure, and substructural identification may be carried out without measuring the actual input excitation to the whole structure. Example analysis is carried out for idealized structural models of a multistory building and a truss bridge. The results indicate that the present method is effective and efficient for local damage estimation of complex structures.

• Journal of the Korean earth science society
• /
• 제26권2호
• /
• pp.114-128
• /
• 2005

Fuzzy information representation of multi-source spatial data is applied to landslide hazard mapping. Information representation based on frequency ratio and non-parametric density estimation is used to construct fuzzy membership functions. Of particular interest is the representation of continuous data for preventing loss of information. The non-parametric density estimation method applied here is a Parzen window estimation that can directly use continuous data without any categorization procedure. The effect of the new continuous data representation method on the final integrated result is evaluated by a validation procedure. To illustrate the proposed scheme, a case study from Jangheung, Korea for landslide hazard mapping is presented. Analysis of the results indicates that the proposed methodology considerably improves prediction capabilities, as compared with the case in traditional continuous data representation.

• The Transactions of the Korean Institute of Power Electronics
• /
• 제24권2호
• /
• pp.92-98
• /
• 2019

Accurate estimation of motor parameters is required in some motor control applications. For example, the value of stator resistance is required for stator flux-oriented control mostly used in doubly fed induction generator systems. Stator resistance is not a constant value and continuously changes due to the rise in temperature during motor operation. Estimation errors degrade the control performance. Hence, this study proposes a simple stator resistance estimation method. In this scheme, the differential components of voltage and current values are used to eliminate the dead-time effect, and Kalman filter algorithm is applied to reduce the error according to measurement noise. Simulation and experimental results obtained with a permanent magnet motor show the validity of the proposed algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• 제33권10A호
• /
• pp.941-948
• /
• 2008

In this paper, the effect of unobtainable channel frequency response (CFR) inside virtual subcarreiers on DFT-based channel estimation is derived and introduced numerically because the CFRs cause the leakage to the estimated channel and degrade the estimation performance. In addition, the performance of DFT-based channel estimation is analyzed with respect to the number of virtual subcarriers, pilot spacing and the number of unobtainable CFRs at equi-distance subcarriers inside virtual subcarriers.

• Journal of Power Electronics
• /
• 제16권1호
• /
• pp.1-8
• /
• 2016

Dead time is typically incorporated in voltage source inverter systems to prevent short circuit cases. However, dead time causes an error between the output voltage and reference voltage. Hence, voltage equation-based algorithms, such as motor parameter estimation and back electromotive force (EMF)-based sensorless algorithms, are prone to estimation errors. Several dead-time compensation methods have been developed to reduce output voltage errors. However, voltage errors are still common in zero current crossing areas, and an effect of the error is much worse in a low speed region. Therefore, employing voltage equation-based algorithms in low speed regions is difficult. This study analyzes the conventional dead-time compensation method and output voltage errors in low speed operation areas. A current shaping method that can reduce output voltage errors is also proposed. Experimental results prove that the proposed method reduces voltage errors and improves the accuracy of the parameter estimation method and the performance of the back EMF-based sensorless algorithm.

• Journal of information and communication convergence engineering
• /
• 제16권1호
• /
• pp.17-22
• /
• 2018

In massive multiple-input multiple-output (MIMO) systems, linear channel estimation algorithms are widely applied owing to their simple structures. However, they may cause pilot contamination, which affects the subsequent data detection performance. Therefore, herein, for an uplink multicell massive multiuser MIMO system, we consider using an alternating projection (AP) for channel estimation to eliminate the effect of pilot contamination and improve the performance of data detection in terms of the bit error rates as well. Even though the AP is nonlinear, it iteratively searches the best solution in only one dimension, and the computational complexity is thus modest. We have analyzed the mean square error with respect to the signal-to-interference ratios for both the cooperative and non-cooperative multicell scenarios. From the simulation results, we observed that the channel estimation results via the AP benefit the following signal detection more than that via the least squares for both the cooperative and non-cooperative multicell scenarios.

• Proceedings of the KSME Conference
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.653-658
• /
• 2000

A driving load estimation method for intelligent cruise control(ICC) vehicles has been proposed in this paper. The driving load is one of the most important factors of perturbations in vehicle control and can affect the control performance critically. The Effect of the control with driving load estimation on vehicle-to-vehicle distance control has been presented and investigated via computer simulations and vehicle tests. The results show that the control with driving load estimation can provide ICC system with a good acceleration tracking performance. In addition, the results show that driving load estimation can compensate not only variation of driving load but also the modeling errors.

• MALSORI
• /
• 제67호
• /
• pp.121-133
• /
• 2008

To estimate directions of multi-sound sources, we consider an approach based on zero crossings which provided more robust results to diffuse noise than the conventional cross-correlation-based method [6][7]. In reverberant environments, the performance of source direction estimation can be improved by using signal components through direct paths from sources to microphones. Since a cepstral prefiltering technique [8] removes the effect of reverberation, we propose a source direction estimation method which can find out intervals of the direct-path components by comparing original and cepstral-prefiltered envelopes. Simulations demonstrate that the proposed method can improve the performance of source direction estimation in reverberant environments.

• Proceedings of the Korea Contents Association Conference
• /
• 한국콘텐츠학회 2007년도 추계 종합학술대회 논문집
• /
• pp.724-726
• /
• 2007

Many enterprises make use of 'mecenat action' for positive image ensuring to company and harmony within organization members. Also, at the same time the research has continued estimating of efficiency about that area. but that estimations get accomplished inclusive and abstractive, and then estimation of significant effect isn't sufficient. In this study we consider that many enterprises practice culture and art education program, and related that analyze the estimation of effect in 'mecenat action'. Stand on this analysis we attempts to extract factor, having representation character with making standard for estimation of education effect. That is a implication that relation education programs are prepared many enterprises, In future study, we will need to make standard and select methods about effect estimation, add measurable index that reliability can increase.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• 제34권12C호
• /
• pp.1208-1215
• /
• 2009

In OFDM systems, mobile channel degrades the system performance seriously. Therefore, channel estimation technique is required to compensate for the degradation from the channel effects. However, conventional channel estimations in frequency domain induce ICI which is induced from Doppler frequency. In addition, a linear interpolation method causes inaccurate channel estimation. In order to minimize the effect of the interference and interpolation error, the proposed method combines LS method and Kalman filtering algorithm. Channel impulse response is adaptively tracked by Kalman filtering based on the information from LS estimator. Simulation results are presented to verify the performance of the proposed channel estimation over mobile channel environment. Simulation results show that the proposed method can effectively compensate for channel degradation.