• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.13-15
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• 2000

This paper suggests the optimal dispatch method by MLF, that gives the appropriate price signal considering power flow and system losses under zonal pricing market. This price signal with MLF effects to dispatch merit order and customer price in the short term, and to connection point of new plant in the long term. In the case study, optimal MLF dispatch method applied to simplified Korean power system. The result shows reduction of loss and northward flow.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.12
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• pp.1137-1142
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• 2010

This paper studied the speech parameters less affected by the human emotion for the development of the robust speech recognition system. For this purpose, the effect of emotion on the speech recognition system and robust speech parameters of speech recognition system were studied using speech database containing various emotions. In this study, mel-cepstral coefficient, delta-cepstral coefficient, RASTA mel-cepstral coefficient and frequency warped mel-cepstral coefficient were used as feature parameters. And CMS (Cepstral Mean Subtraction) method were used as a signal bias removal technique. Experimental results showed that the HMM based speaker independent word recognizer using vocal tract length normalized mel-cepstral coefficient, its derivatives and CMS as a signal bias removal showed the best performance of 0.78% word error rate. This corresponds to about a 50% word error reduction as compare to the performance of baseline system using mel-cepstral coefficient, its derivatives and CMS.

• The Journal of the Acoustical Society of Korea
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• v.18 no.2
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• pp.40-47
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• 1999

Focusing is widely used to increase the resolution in ultrasound transmit field. It increases signal levels returning from the mainlobe direction and decreases those due to sidelobe directions. However, when the sidelobes cannot be completely canceled, the resulting image resolution is greatly deteriorated. This paper proposes a method of improving the resolution by scaling the received signal according to the difference between the mainlobe and sidelobe levels computed in the frequency domain by the use of Fourier transform. The proposed method is verified by computer simulation and experiments, and is shown to be highly effective in narrowing the mainlobe width and decreasing the sidelobe levels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.467-472
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• 2008

One of the maindisadvantages of Orthogonal Frequency Division Multiplexing (OFDM) is the Peak to Average Power Ratio (PAPR) problem. To reduce PAPR and improve the error performance of the OFDM signal over a fading channel, an OFDM system combining an Adaptive Symbol Selection Scheme (ASSS) and channel estimation can be used. Because of the side information of ASSS, however, the data rate decreases in the conventional ASSS OFDM system. In this letter, to overcome this impairment, we propose a technique to transmit side information by using pilot tones, and demonstrate that the proposed technique can give reasonable bit error rate (BER) performance.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.138-140
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• 1992

This paper represents how to reduce the computer time in small signal stability analysis by selecting the dominant oscillation modes with frequency of 0.5 to 1.2 Hz using the clustering technique. Clustering technique links the buses which are expected to be similar with zero-impedance lines and the voltage variations of these buses are regarded to be identical. The computer time was reduced remarkably with this technique and the effect of clustering will be powerful in the analysis of large-scale power systems.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1098-1102
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• 1990

We consider a method for enhancement of speech signal degraded by additive random noise with time-variant and/or colored natures. For enhancement of speech signal with such noise, it is effective to utilize the natures of speech and noise. The objective of enhancement of speech is to improve the overall quality and the articulation of speech degraded by the time-variant and/or colored random noise. In the proposed method the distribution model of speech spectrum is given as information to noise reduction system. The proposed system can improve about lOdB in SNR when the input SNR is 0 dB.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.857-865
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• 2010

Recently the demand of the driverless rolling stock is increasing with advancement of the stable communication technique and control technique. The automatic train operating system has advantages which takes low operating cost and is able to dispose elastically in demand. Beside it provides high safety and effectiveness because it will be able to control power, signal and communication system from Operation Control Center and the safety and effectiveness are high. The establishment of PSD, Platform Screen Door, is advanced in the goal which is passenger safety, fire protection, noise and dust reduction etc. When but, two advanced systems also have risks of operation delay and accident when two systems are not controlled smoothly. Thus, I'll introduce control method between onboard controller, door control unit in rolling stock and PSD controller to help system design.

• Journal of Korean Society for Quality Management
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• v.23 no.2
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• pp.28-42
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• 1995

For quality improvement, Taguchi emphasizes the reduction of variation of the quality characteristic, Taguchi has used the signal-to-noise ratios for achieving minimum dispersion of the quality characteristic with its location adjusted to some desired target value ${\tau}$ Lim(1994) proposes a reasonable SN ratio based on a linking relationship of the variance and mean through simple data analysis technique. In this paper we investigate the efficiency of those two SN ratios and variance stabilizing transformations through Monte Carlo Simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.736-741
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• 2004

In high-capacity disk drives with ever-growing track density, the allowable level of position error signal (PES) is becoming smaller and smaller. In order to achieve the high TPI disk drive, it is necessary to improve the writing accuracy during the STW(servo track writing) process through the reduction of TMR sources. Among the main contributors of the NRRO(Non-Repeatable Run-out) PES, the disk vibration and the HSA(head-stack assembly) vibration is considered to be one of the most significant factors. Also the most contributors of RRO(Repeatable Run- out) come from the contributors of NRRO which is written-in at the time of STW(servo track writing) process. In this paper, the experimental test result shows that the effect of NRRO on servo written-in RRO effectively can be reduced through a STW process under low dense medium condition such as semi-vacuum.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.435-438
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• 1997

One of the main techniques or diagnosing heart disease is by examining the electrocardiogram(ECG). Many studies on detecting the QRS complex, P, and T waves have been performed because meaningful information is contained in these parameters. However, the earlier detecting techniques can not effectively extract those parameters from the ECG that is severely contaminated by noise source such 60Hz powerline interference, motion artifact and baseline drift. in this paper, we performed the extracting parameters from and recovering the ECG signal using wavelet transform that has recently been applying to various fields.