• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1149-1154
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• 2017

To obtain good recognition performance of speech recognition system under background noise, it is very important to select appropriate feature parameters of speech. The feature parameter used in this paper is Mel frequency cepstral coefficient (MFCC) with the human auditory characteristics applied to Wiener filter method. That is, the feature parameter proposed in this paper is a new method to extract the parameter of clean speech signal after removing background noise. The proposed method implements the speaker recognition by inputting the proposed modified MFCC feature parameter into a multi-layer perceptron network. In this experiments, the speaker independent recognition experiments were performed using the MFCC feature parameter of the 14th order. The average recognition rates of the speaker independent in the case of the noisy speech added white noise are 94.48%, which is an effective result. Comparing the proposed method with the existing methods, the performance of the proposed speaker recognition is improved by using the modified MFCC feature parameter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.469-472
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• 2005

This paper propose about effective speech feature parameter that have robust character in effect of noise in realizing speech recognition system. Established MFCC that is the basic parameter used to ASR(Automatic Speech Recognition) and DCTCs that use DCT in basic parameter. Also, proposed delta-Cepstrum and delta-delta-Cepstrum parameter that reconstruct Cepstrum to have information for variation of speech. And compared recognition performance in using HMM. For dimension reduction of each parameter LDA algorithm apply and compared recognition. Results are presented reduced dimension delta-delta-Cepstrum parameter in using LDA recognition performance that improve more than existent parameter in noise environment of various condition.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.4
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• pp.1-7
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• 2007

Flow rate is one of the important variables for precise motion control and detection of the faults and fluid loss in many hydraulic components and systems. But in many cases, it is not easy to measure it directly. The orifice area of a servo valve by which the fluid flows is one of key factors to monitor the flow rate. In this paper, we have constructed an estimation algorithm for the effective orifice area by using the model of a servo valve cylinder control system and Kalman filter algorithm. Without geometry information about the servo valve, it is shown that the effective orifice area can be estimated by using only displacement and pressure data corrupted with noise. And the effect of the biased sensor data and system parameter errors on the estimation results are discussed. The paper reveals that sensor calibration is important in accurate estimation and plausible parameter data such as oil bulk modulus and actuator volume are acceptable for the estimation without any error. The estimation algorithm can be used as an useful tool for detecting leakage, monitoring malfunction and/or degradation of the system performance.

• Computers and Concrete
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• v.23 no.2
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• pp.145-153
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• 2019

Adaptive schemes are constructed in this paper for modeling the effective chloride diffusion coefficient of cement-based materials (paste and concrete). Based on the polarization approximations for the effective conductivity of isotropic multicomponent materials, we develop some fitting procedures to include more information about the materials, to improve the accuracy of the scheme. The variable reference parameter of the approximation involves a few free scalars, which are determined through the available numerical or experimental values of the macroscopic chloride diffusion coefficient of cement paste or concrete at some volume proportions of the component materials. The various factors that affect the chloride diffusivity of cement-based material (porous material structure, uncertainty of value of the chloride diffusion coefficient in water-saturated pore spaces, etc.) may be accounted to make the predictions more accurate. Illustrations of applications are provided in a number of examples to show the usefulness of the approach.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.827-832
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• 2018

Research on effective dose analysis of actual conditions of use based on large data is scarce. In this study, the exposure conditions of Chest X-Ray examinations used by 324 medical institutions in Korea were calculated and evaluated using computer simulations. As a result of the experiment, the effective dose in the low energy parameter bands was 0.024 mSv, followed by spleen, adrenal glands, and lung. The effective dose in the high-energy exposure parameter band was 0.123 mSv, followed by height, spleen and adrenal glands. The effective dose was 0.017 mSv when the optimal conditions considered the quality and exposure proposed in Park's study were used. The results of the study will be a reference for chest X-rays and will help reduce patient exposure.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.205-215
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• 2015

Common mode (CM) conducted interference are predicted and compared with experiments in a motor drive system of Electric vehicles in this study. The prediction model considers each part as an equivalent circuit model which is represented by lumped parameters and proposes the parameter extraction method. For the modeling of the inverter, a concentrated and equivalent method is used to process synthetically the CM interference source and the stray capacitance. For the parameter extraction in the power line model, a computation method that combines analytical method and finite element method is used. The modeling of the motor is based on measured date of the impedance and vector fitting technique. It is shown that the parasitic currents and interference voltage in the system can be simulated in the different parts of the prediction model in the conducted frequency range (150 kHz-30 MHz). Experiments have successfully confirmed that the approach is effective.

• Journal of Biomedical Engineering Research
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• v.22 no.3
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• pp.269-273
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• 2001

Proper determination of pacing threshold is important for patient safety and pacemaker longevity. In general, cardiac muscle contractions caused by pacing pulses are verified by observing the morphology of surface ECG displayed on a monitor. In this study, a method of automatic pacing threshold determination based on morphological difference between intrinsic and paced ECGs was developed. First, characteristics of intrinsic ECG and paced ECG were analyzed in time and frequency domain and a proper discrimination parameter was extracted. Then, the automatic capture verification method based on the parameter was developed and applied to 23 pacemaker patients. The selected parameter was the area of ventricular depolarization wave during 80ms after pacing stimulus. It was found that the method was reliable and effective in identifying paced ECG and, thereby, determing a proper pacing threshold.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.273-277
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• 2007

In case of the Hydraulic Turbine Dynamo operating for Waterpower Generation, it makes very huge and loud noises, and it influences bad effect physically as same as mentally to those people who are working inside of power plant, and brings the decline of an effective working efficiency. However, its evaluation method or measure about such noise reflects merely its physical attribute which is sensuous Loudness of the Noise itself, since the accumulation effect of Noise or the meaning connected with psychological response did not reflect, it is the actual state that a rational evaluation is unable to expect. Consequently, this Study has attempted to evaluate the Noise of Hydraulic Turbine Dynamo by analyzing the sound quality using Zwicker‘s Psychological Acoustic Parameter, after classification by its positions of the Noise occurring at Hydraulic Turbine Dynamo.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.1
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• pp.14-20
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• 1996

This paper presents a self tuning method of a velocity type PID controller for minimum or non-minimum phase systems with time delays. The velocity type PID control structure is determined in the process of minimizing the variance of the auxilliary output, and self tuning effect is achieved through the recursive least square algorithm at the parameter estimation stage and also through the Robbins-Monro algorithm at the stage of optimizing a design parameter. This method is simple and effective compared with other existing methods[1,2]. Numerical examples are included to illustrate the procedure and to show the performance of the control system.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.157-178
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• 2001

In this paper, the nonlinear control of high precision pointing stabilization system using feedback-linearization design methodology based on system parameter identification is discussed. Modern nonlinear servomechanism theory is adapted to cope with the hard nonlinearities inherent in the turret system. The mathematical models of electrical turret driving system to develop a high performance control algorithm are derived, and the parameter estimation algorithm identifying the unknown system parameters such as vicious and coulomb frictions, stiffness and inertia is developed. Through computer simulation and experiments, it is shown that pointing and tracking accuracy and stabilization against the wideband stochastic disturbance induced by vehicle running on the bump course are improved. Therefore, it is considered the proposed nonlinear control technique is effective in counteracting the nonlinearities and disturbances.