• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.43-48
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• 1992

In the area of speech vocoder systems, the MBE vocoder allows the high quality and low bit rate. In the MBE parameters detection, the dicision methods of V/UV region proposed until now are dependent highly to the other parameters, fundamental frequency and formant information. In this paper, thus, we propose a new V/UV detection method that uses a zero-crossing rate of flatten harmonices spectrum. This method can reduce the influences of the other parameters for the V/UV regions detection.

• Journal of Korean Society of Forest Science
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• v.88 no.4
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• pp.485-489
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• 1999

The germination percentages of Quercus hybrid seeds produced in 1994 using stored pollens were low. The survival rate and height growth within 2 years differed according to crossing combinations. The survival rate and growth of seedlings from hybrid seeds produced in 1991 and 1993 were investigated. The survival rates of five-year-old and three-year-old seedlings were from 71 to 100% and from 33 to 100%, respectively. The survival rates differed according to cross combinations. The mortality of seedlings increased in proportion to the increase of percentages of dwarf seedlings. The growth of five-year-old seedlings, of which mother tree was Q. aliena, was the best. The growth of seedlings produced by artificial crossing tended to be worse than that of natural crossing.

• ETRI Journal
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• v.29 no.3
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• pp.292-299
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• 2007

In this paper, we present a speech recognition system using a throat microphone. The use of this kind of microphone minimizes the impact of environmental noise. Due to the absence of high frequencies and the partial loss of formant frequencies, previous systems using throat microphones have shown a lower recognition rate than systems which use standard microphones. To develop a high performance automatic speech recognition (ASR) system using only a throat microphone, we propose two methods. First, based on Korean phonological feature theory and a detailed throat signal analysis, we show that it is possible to develop an ASR system using only a throat microphone, and propose conditions of the feature extraction algorithm. Second, we optimize the zero-crossing with peak amplitude (ZCPA) algorithm to guarantee the high performance of the ASR system using only a throat microphone. For ZCPA optimization, we propose an intensification of the formant frequencies and a selection of cochlear filters. Experimental results show that this system yields a performance improvement of about 4% and a reduction in time complexity of 25% when compared to the performance of a standard ZCPA algorithm on throat microphone signals.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.57-63
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• 2006

This paper deals with the physical properties and statistical analysis of waveform parameters of electric and magnetic folds radiated from lightning return strokes. The lightning electric and magnetic fields were detected by an plate-type electric field sensor and a loop-type magnetic field sensor respectively, and they were recorded by a data acquisition system having a resolution of 12bits, a sampling rate of 10[MS/s] and recording length of 10[ms]. As a result, a little difference between the parameters of electric and magnetic fields for positive and negative polarities was observed. The rise times of electric and magnetic fields were within the range of less than $13[{\mu}s]$ and the average values for positive and negative polarities were $4.1[{\mu}s]\;and\;4.2[{\mu}s]$, respectively. The average values of the zero-to zero crossing times were $65.2[{\mu}s]\;and\;67.0[{\mu}s]$, and the average depths of the dip to opposite polarity were 38.0[%] and 40.3[%], for positive and negative polarities, respectively.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.117-124
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• 2006

The modern convenient life formed by industrial development becomes lack of exercise and takes an interest in diet. Specially, professional walking shoes is developed as people take an interest in jogging, Those shoes, professional walking shoes or Dietshoes, increase exercise effects by change of heel types. Therefore, this study investigated motility effects by EMG experiment in order to measure Muscle Activities (MA) while wearing diet shoes (backless). Experiment was conducted by EMG measurement, from calf (gastrocnemius muscle), thigh (vastus muscle) and waist (erector spinae muscle), of 12 high school students. Exercise effects between the two shoes were analyzed by EMG (MF; Median Frequency, MPF; Mean Power Frequency, ZCR; Zero Crossing Rate). Results showed that the Dietshoes(MF: 48.21Hz, MPF: 65.0Hz, ZCR: 100.6Hz) had larger EMG value than that of Normal shoes(MF: 40.47Hz, MPF: 58.04Hz, ZCR: 82.09Hz). Also, in MA, the highest activities are showed in the calf, the second one is in waist, and last one is in thigh during gate. ANOVA between shoes in measurement parts showed significant effects in MF (gastrocnemius: p-value=.022, vastus laterals: p-value=.037, erector spinae: p-value=.082), MPF (gastrocnemius: p-value=.032, vastus laterals: p-value=.046, erector spinae: p-value=.090), and ZCR (gastrocnemius: p-value=.000, vastus laterals: p-value=.004, erector spinae: p-value=.134). And MA of Dietshoes is higher than that of Normal shoes, and decreasing rate of MA in Dietshoes is less than that of Normal shoes. Thus, this study validates exercise effects of Dietshoes.

• Journal of the Korean Statistical Society
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• v.36 no.2
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• pp.285-297
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• 2007

We consider the $P_{\lambda}^M-service$ policy for an M/G/1 queueing system in which the workload is monitored randomly at discrete points in time. If the level of the workload exceeds a threshold ${\lambda}$ when it is monitored, then the service rate is increased from 1 to M instantaneously and is kept as M until the workload reaches zero. By using level-crossing arguments, we obtain explicit expressions for the stationary distribution of the workload in the system.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.881-883
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• 1987

This paper decribes a new technique for the generation of excitation sources in LPC system. We synthesize a speech signal using several excitation sources, according to residual signal energy and ZCR(zero Crossing Rate). One of the excitation sources mix the double differentiated glottal wave form source and noise source. As a result, we got improved speech signal than that produced by conventional LPC system.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.12
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• pp.1663-1669
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• 1995

This paper is a study on the recognition of Korean proverb using neural network and Markov model. The neural network uses, at the stage of training neurons, features such as the rate of zero crossing, short-term energy and PLP-Cepstrum, covering a time of 300ms long. Markov models were generated by the recognized phoneme strings. The recognition of words and proverbs using Markov models have been carried out. Experimental results show that phoneme and word recognition rates are 81. 2%, 94.0% respectively for Korean proverb recognition experiments.

• The Journal of the Acoustical Society of Korea
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• v.32 no.5
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• pp.408-414
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• 2013

The famous filtered-x least mean square (FxLMS) algorithm for active noise control (ANC) systems may become unstable in non-stationary noise environment. To solve this problem, Sun's algorithm and Akhtar's algorithm are developed based on modifying the reference signal in update of FxLMS algorithm, but these two algorithms have dissatisfactory stability in dealing with sustaining impulsive noise. In proposed algorithm, probability estimation and zero-crossing rate (ZCR) control are used to improve the stability and performance, at the same time, an optimal parameter selection based on fuzzy system is utilized. Computer simulation results prove the proposed algorithm has faster convergence and better stability in non-stationary noise environment.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.5
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• pp.31-36
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• 2011

In this paper, Mel-Frequency Cepstral Coefficient (MFCC), Decorrelated Filter Bank (DFB), Octave-based Spectral Contrast (OSC), Zero-Crossing Rate (ZCR), and Spectral Contract/Roll-Off are combined as a set of multiple feature-vectors for the music genre classification system based on the Support Vector Machine (SVM) classifier. In the conventional system, feature vectors for the entire genre classes are normalized for the SVM model training and classification. However, in this paper, selected feature vectors that are compared based on the One-Against-One (OAO) SVM classifier are only used for normalization. Using OSC as a single feature-vector and the multiple feature-vectors, we obtain the genre classification rates of 60.8% and 77.4%, respectively, with the conventional normalization method. Using the proposed normalization method, we obtain the increased classification rates by 8.2% and 3.3% for OSC and the multiple feature-vectors, respectively.