• Proceedings of the KSR Conference
• /
• 2009.05b
• /
• pp.259-264
• /
• 2009

This paper proposes a real-time estimation of the boost inductance in a single-phase AC/DC parallel PWM converter for high-speed EMU. The estimation procedure of the boost inductance is only based on the variation of input current and the input AC voltage measurement. The estimated boost inductance is optimized by the least square method. This estimation technique can improve the performance of current controller and reduce the harmonics of the input current in the feed-forward controller. The validity of proposed technique is verified through the MATLAB SIMULINK simulation results.

• The Korean Journal of Applied Statistics
• /
• v.14 no.1
• /
• pp.13-24
• /
• 2001

In this paper, we investigated mean estimation methods in two-phase sampling. Under the fixed expected cost we reviewed the optimal sample sizes, minimum variances and approximate unbiased variance estimators for usual ratio estimator, stratified sample mean with proportional allocation and Rao's allocation of the second phase sample. Also we proposed combined ratio estimator, which uses both ratio estimation and stratification and derived optimal sample size, minimum variance and unbiased variance estimator. Through a limited simulation study, we compared estimators by design effects and came to know that ratio estimator is more efficient than stratified sample mean in some cases and inefficient in the other cases, but combined ratio estimator is more efficient than others in most cases.

• Journal of the Korean Data and Information Science Society
• /
• v.23 no.6
• /
• pp.1085-1091
• /
• 2012

Phase I clinical trials are designed to identify an appropriate dose; the maximum tolerated dose, which assures safety of a new drug by evaluating the toxicity at each dose-level. The adjusted maximum tolerated dose estimation is presented by stopping rule in phase I clinical trial on this research. The suggested maximum tolerated dose estimation is compared to the standard method3 and NM method using a Monte Carlo simulation study.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.1A
• /
• pp.51-57
• /
• 2002

In this paper, a simple interpolation technique in a frequency domain is proposed for the discrete Fourier transform(DFT) algorithm. Frequency and phase resolution capabilities of the DFT algorithm can be significantly improved by the proposed interpolation technique without increase of a DFT size(the number of points for the DFT). The new technique uses a diving point in amplitude and phase spectrums. As an application, the technique can be used for joint estimation of fine frequency and phase offsets in burst mode digital transmission. Simulation results show that the joint estimator using the technique is robust to estimation errors.

• The Journal of the Acoustical Society of Korea
• /
• v.43 no.4
• /
• pp.406-413
• /
• 2024

The proposed method uses Generalized Cross Correlation - Phase Transform (GCC-PHAT) method with nonlinear preprocessing and a frequency domain low-pass filter. In this paper, by reinterpreting the calculation process of GCC-PHAT as DFT, we derive that there is an effective frequency band used for time delay estimation in GCC-PHAT, and by using only the effective band using a low-pass filter, the noise component is reduced and it improvesthe time delay performance in impulsive noise environments. By comparing the proposed method with the traditional GCC-PHAT in an impulsive noise environment, we show that the GCC-PHAT becomes more robust to the impulsive noise.

• Proceedings of the KIEE Conference
• /
• 1992.07a
• /
• pp.377-380
• /
• 1992

This paper proposes a novel direct adaptive pole placement control algorithm which can be applied to continuous time nonminimum phase systems. The algorithm is based on Lyapunov's direct method. By introducing an auxiliary signal, a minimal error model is constructed in state space. Using the error model an estimation law is obtained via Lyapunov's second stability theorem. The global stability of the overall system is established.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.11 no.3
• /
• pp.211-216
• /
• 1986

This paper presents theoretical analysis and experimental results on an improved interference rejection circuit in the presence of continuous wave interference at center frequency, particularly in a wide-band communication systems. This circuit is based upon a phase locked loop for estimating the CW interference phase and the MSE technique to minimize the estimation error. Therefore, the introduced rejection circuit that minimized the estimated phase error outperforms the rejection circuit with phase estimation only. As a result of experiment, we confirm that this proposed rejection circuit gives a high degree of interference rejection performances when the input J/S is large.

• Journal of Advanced Navigation Technology
• /
• v.11 no.2
• /
• pp.170-176
• /
• 2007

In this paper, we improve performance for system when the carrier recovery signal is not perfect in the multipath mobile wireless communication fast fading channel based on DS-CDMA system. In the case, we use the phase estimation, diversity and adaptive FEC code technique in order to overcome this carrier phase error and mobile wireless fading. As a results in DS-CDMA system, we know that the appropriate use of diversity and adaptive FEC code technique reduced considerably performance degradation due to phase error.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.4
• /
• pp.324-329
• /
• 2017

The phase controlled rectifier using thyristor is suitable for the high capacity and low-cost system. However, the rectifier output voltage drop is influenced by the grid inductance effect. Supposing the commutation area voltage and current are analyzed, the grid inductance can be estimated using the proposed algorithm. This paper presents the grid inductance estimation method for improved commutation compensation control of the phase controlled rectifier, and the proposed control algorithm effectiveness is verified by simulation.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.5
• /
• pp.680-688
• /
• 1986

In order to obtain the optimal estimation method of fracture toughness of dual phase steel in which martensitic phase encapsulated islands of ferritic phase, the stretched zone (SZ) method and the R-curve method of the JSME S 001 was discussed. The results obtained are as follows. (1) The $J_{IC}$ values estimated by the SZ method are overestimated as compared with those by the R-curve method. (2) The $J_{IC}$ by the R-curve method decreases with the increase of the ferrite grain size and the martensite hardness. (3) The overestimation of $J_{IC}$ by the SZ method is due to the continuous plastic blunting of ferrite after the formation of stable crack which affects the critical stretched zone width.