• Speech Sciences
• /
• v.7 no.3
• /
• pp.185-195
• /
• 2000

This paper seeks to compare the feature parameters used in speaker identification systems under noisy environments. The feature parameters compared are LP cepstrum (LPCC), Cepstral mean subtraction(CMS), Pole-filtered CMS(PFCMS), Adaptive component weighted cepstrum(ACW) and Postfilter cepstrum(PF). The GMM-based text independent speaker identification system is designed for this target. Some series of experiments show that the LPCC parameter is adequate for modelling the speaker in the matched environments between train and test stages. But in the mismatched training and testing conditions, modified parameters are preferable the LPCC. Especially CMS and PFCMS parameters are more effective for the microphone mismatching conditions while the ACW and PF parameters are good for more noisy mismatches.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.13 no.4
• /
• pp.340-351
• /
• 1988

Up to now, hybrid torque/position control of robot manipulator have been researched under the assumption that link mass and/or load are known. This paper proposes a torque and position control method under unknown mass of links or load of a robot manipulator and the method extend control in joint space to control in operational space. In the method, known parameters are used to estimate unknown parameter. We illustrate the theory with some simulations and show that the result is effective.

• Proceedings of the KIEE Conference
• /
• 1988.07a
• /
• pp.93-97
• /
• 1988

The sliding mode control is an effective method to establish robustness against parameter variations and disturbance. But, in sliding mode strategy, the control function is discontinuous on the hyperplane. Consequently, the control input chatters at high frequency. When we apply such a control to the induction motor drive system, that causes a torque ripple and current harmonics, which are harmful to the system. In this paper, we introduce a low pass filter between sliding mode control output and driver input to overcome that problem. The band-width of this filter is varied according to the error funtion to improve transient responses.

• Proceedings of the KIEE Conference
• /
• 1988.07a
• /
• pp.65-68
• /
• 1988

In this paper the application of variable structure control with sliding modes for improving the dynamic response and eliminating chattering of DC servo motor drive is presented. Sliding mode control is an effective means to keep a system insensitive to parameter variation and disturbances. In this method the control structure is changed discontinuously to farce the system dynamic to follow a predetermined trajectory. However the discontinuous change in control structure causes the controller input to chatter and gives non-zero steady state error. To overcome this problem, the discontinuous sign function is replaced by a proper continuous function, and presented through experiment.

• 전기의세계
• /
• v.18 no.1
• /
• pp.15-23
• /
• 1969

A lot of recent researches have shown that a Pseudo Random Binary Signal is a quite effective test signal to measure the impulse response of a plant. Generally speaking, however, such a response itself is not satisfactory to determine the appropriate control parameters or control inputs. Here, the author intends to estimate the unknown parameters of the First Order Plant with Dead Time by means of correlation method using M-sequence signal. The time constant T and the dead time L of the plant are eatimated with one tracking loop by automatically adjusting delay time .tau. of M-sequence signal according to variations of T and L. In this paper, a three level M-sequence signal is used as a test signal in order to avoid troublesome operations to calculate partial derivatives of a given performance index with respect to the parameters which are usually required in the Model Method. Several experiments with analogue computer using low pass filters as averaging circuits showed good results as expected.

• Proceedings of the KIEE Conference
• /
• 2001.07e
• /
• pp.58-61
• /
• 2001

The purpose of this paper is a fuzzy logic controller for XY positioning system. The overall control system consists of three parts, the position controller, the speed controller, the fuzzy logic controller. Precise tracking is achieved by fuzzy logic controller. In practice, such systems contain many uncertainties. Therefore, the XY positioning system must receive and evaluate the motion of all axis for a better contouring accuracy. Cross coupled controller utilizes all axis position error information simultaneously to produce accurate contours. However, the existing Cross coupled controllers cannot overcome friction, backlash and parameter variation. So, we propose a fuzzy logic controller of XY positioning system. Experimental results show that the proposed fuzzy logic controller is effective to improve the contouring accuracy of XY positioning system.

• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.972-974
• /
• 1997

Design & Operation of power system for meeting increase of electric Power demand is becoming more difficult and complex. One of reasons is increase of fault current. As one of the most effective methods for suppressing the fault current installation of SFCL is expected. These paper describes a method of fault analyses of power system with SFCLs, and also discusses determination of specification of SFCLs, effects of limiting the fault current due to SFCLs by use of the model system of two - bus electric power system with single transmission lines.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.17 no.1
• /
• pp.89-94
• /
• 2018

The electric power system design of the electric vehicle are required to improve the performance. The electric power system on the electric vehicle are consist of a battery, a pedal sensor, an electric motor and a controller. In this paper, Automotive manufacture's various electric vehicle models are investigated and analyzed. The mathematical models for the electric power system are studied, and then important variables are considered. Simulation and experimental test results show the model of the electric power system on the electric vehicle and design parameter decision are effective to the electric vehicle design.

• Journal of Magnetics
• /
• v.10 no.2
• /
• pp.71-75
• /
• 2005

An effective method, i.e., the solid atom method, is suggested to obtain the Coulomb interaction parameter, U, and the Hund exchange coupling constant, J, for use in the LDA+U calculation. The par~meters are obtained self-consistently during the LDA+U calculation. The method is applied to typical transition metal oxides and $MnB^{VI}(B^{VI}=S,Se,Te)$. The U values for the transition metal oxides have similar magnitude to previous calculations although they are obtained by a much simpler method. $MnB^{VI}s$ have been characterized as crossroads materials between charge transfer and band insulators by the LDA+U calculation.

• Nuclear Engineering and Technology
• /
• v.33 no.2
• /
• pp.156-165
• /
• 2001

A radiological safety assessment was performed for a hypothetical near-surface radioactive waste repository as a simple screening calculation to identify important nuclides and to provide insights on the data needs for a successful demonstration of compliance. Individual effective doses were calculated for a conservative ground water pathway scenario considering well drilling near the site boundary. Sensitivity of resulting ingestion dose to input parameter values was also analyzed using Monte Carlo sampling. Considering peak dose rate and assessment time scale, C-14 and T-129 were identified as important nuclides and U-235 and U-238 as potentially important nuclides. For C-14, the dose was most sensitive to Darcy velocity in aquifer The distribution coefficient showed high degree of sensitivity for I-129 release.