• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1291-1295
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• 2004

This paper proposed a new approach for endpoint detection of isolated speech, which proves to significantly improve the endpoint detection performance. The proposed algorithm relies on the root mean square energy (rms energy), zero crossing rate and spectral characteristics of the speech signal where the Euclidean distance measure is adopted using cepstral coefficients to accurately detect the endpoint of isolated speech. The algorithm offers better performance than traditional energy-based algorithm. The vocabulary for the experiment includes English digit from one to nine. These experimental results were conducted by 360 utterances from a male speaker. Experimental results show that the accuracy of the algorithm is quite acceptable. Moreover, the computation overload of this algorithm is low since the cepstral coefficients parameters will be used in feature extraction later of speech recognition procedure.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.235-236
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• 2016

본 논문에서는 400Hz 항공기용 3상 4선식 인버터의 전압 제어에 대해 연구하였다. 시스템에서 불평형이 발생하면 중성선 전류가 증가하며 이에 따라 출력전압 불균형 및 왜곡 증가 등 시스템에 심각한 문제를 발생시킨다. 전압의 크기를 제어해주는 RMS 제어의 경우 불평형 발생 시 전압의 크기는 정상적으로 제어가 가능하지만, THD가 상승하여 전력의 품질이 저하될 수 있다. 다른 제어 방식인 비례 공진(PR) 제어는 순시적으로 제어를 함으로써 전압의 크기뿐만 아니라 위상차 및 THD 감소 등의 향상된 전력 품질을 기대할 수 있다. 두 제어방법의 비교는 시뮬레이션 및 실험을 통해 수행하였으며, 두 제어방법 불평형 발생 시 모두 전압의 크기 오차가 3% 이하로 정상적으로 제어하는 것을 확인하였고, THD는 RMS 제어에 비하여 PR 제어의 결과가 2% 감소하는 것을 확인하였다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.9
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• pp.953-959
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• 1992

As the TC(time-current) curve corresponding to symmetrical time invariant RMS value has been traditionally chosen and used for setting the relay, it has caused the misoperation errors on relay coordination because of CT secondary current being actually an asymmetrical time varying RMS value. In this paper, an algorithm for calculating the relay operating time is developed to study the asymmetrical effect using the step-by-step method. We represent the relay operating time errors between with and without DC offset versus PSM(plug setting multiplier), TMS(time multiplier setting) and X/R ratio. And also we present the correction factor. Finally we confirm the validity of this technique through the case study.

• Journal of Broadcast Engineering
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• v.5 no.2
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• pp.273-280
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• 2000

Channel characteristics between the outdoor transmitter far away from the building and receivers inside the building are explored theoretically using ray tracing technique. In this paper, 29 receivers are located on the single floor of the building to observe the variation of channel properties depending on receiver location. For each receiver, amplitudes and phases of ail the possible rays form the transmitter to the receiver are traced to obtain impulse response. Statistical results for rms delay spread and power delay profiles for representative receiver location are given.

• Speech Sciences
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• v.11 no.1
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• pp.55-64
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• 2004

This study was to determine the effects of a massage and oro-facial exercise program on spastic dysarthric patients' lip muscle function using an electromyogram (EMG). Three subjects with Spastic Dysarthria participated in the study. The surface electrodes were positioned on the Levator Labii Superior Muscle (LLSM), Depressor Labii Inferior Muscle (DLIM), and Orbicularis Oris Muscle (OOM). To examine lip muscle function improvement, the EMG signals were analyzed in terms of RMS (Root Mean Square) values and Median Frequency. In addition, the diadochokinetic movements and the rate of sentence reading were measured. The results revealed that the RMS values were decreased and the Median Frequency moved to a high frequency area. Diadochokinesis and sentence reading rates were improved.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.10
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• pp.41-47
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• 2008

This study aims to obtain machining characteristics during AFM (Atomic force Microscope) machining of silicon wafers and to monitor the machining states using acoustic emission. As in micro scale machining, two distinct regimes of deformation, i. e. ploughing regime and cutting regime were observed. First, the transition between the two regimes are investigated by analyzing the "pile-up" during machining. As far as in process monitoring is concerned, in the ploughing repime, no chips have been formed and related AE RMS values are relatively low, In the mean time, in the cutting regime, the RMS values are significantly higher than the ploughing regime, with apparent chip formation. From the results, we found out that the proposed scheme can be used for the monitoring of nanomachining, especially for the characterization of nanocutting mode transition.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.1910-1920
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• 1993

An experimental study to investigate the unconventional chip formation called triangulation of chip in cutting with a SPRT (self-propelled rotary tool) is performed using acoustic emission (AE) signal analysis. In doing that, a quantitative model of the AE RMS signal in triangulation with a SPRT is first developed. The predicted results from this model show good correlation between the AE RMS signal and the general characteristics of triangular chip formation. Then, effects of various process parameters such as cutting conditions (cutting speed, depth of cut, oblique angle and normal rake angle) and the work material properties on the chip formation in cutting with a SPRT are explored. Special attention is paid to the work material properties which are found to have significant effects on triangulation.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1183-1184
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• 2011

In case of the power conversion converter for driving the Lighting control system, the input voltage widens from $90V_{rms}$ to $264V_{rms}$. Among various methods, LLC half-bridge converter has wide input regulation range and limited switching frequency control range and ZVS is possible for even non-loaded case. Also, the converter can be applied for Universal Lighting control system. In this paper, the transformer design is studied. The efficiency measured is up to 90%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.7
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• pp.549-555
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• 2008

Analytical method to analyze the tolerance effect on the vehicle ride comfort is suggested in this paper. Ride comfort is one of the most important performance indices which decide the vehicle design quality. In general, the ride comfort is affected by the variations of parameters of a vehicle model. Therefore, the effects of the parameters on the ride comfort need to be evaluated statistically based on the whole-body vibration of the vehicle. In this paper, weighted RMS values of the acceleration PSD of a seat position are used to define the ride comfort. The equations of motion and the sensitivity equations are derived based on a 5-DOF vehicle model. By employing the sensitivity information of the acceleration at the seat position, the tolerance effect on the vehicle ride comfort could be effectively analyzed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.3
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• pp.148-151
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• 2013

A new direction of arrival estimation method using effects of model errors and sensitivity analysis is proposed. Since a desired signal is obtained after interference rejection through correction effects of model error, the effect of channel interference on the estimation is significantly reduced. Through simulation, we show that the proposed method offers significantly improved estimation resolution and accuracy relative to existing method.