• Phonetics and Speech Sciences
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• v.5 no.1
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• pp.3-10
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• 2013

This study proposes a method to measure mental fatigue using speech technology, which has not been used in previous research and is easier than existing complex and difficult methods. It aims at establishing a relationship between the human voice and mental fatigue based on experiments to measure the influence of mental fatigue on the human voice. Two monotonous tasks of simple calculation such as finding the sum of three one digit numbers were used to measure the feeling of monotony and two sets of subjective questionnaires were used to measure mental fatigue. While thirty subjects perform the experiment, responses to the questionnaire and speech data were collected. Speech features related to speech source and the vocal tract filter were extracted from the speech data. According to the results, speech parameters deeply related to mental fatigue are a mean and standard deviation of fundamental frequency, jitter, and shimmer. This study shows that speech technology is a useful method for measuring mental fatigue.

• Phonetics and Speech Sciences
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• v.8 no.4
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• pp.9-14
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• 2016

This study investigated the patterns of coda deletion in spontaneous Seoul Korean speech. More specifically, the current study focused on three factors in promoting coda deletion, namely, word position, consonant type, and morpheme type. The results revealed that, first, coda deletion frequently occurred when affixes were attached to the ends of words, rather than in affixes in word-internal positions or in roots. Second, alveolar consonants [n] and [l] in the coda positions of high-frequency affixes [nɨn] and [lɨl] were most likely to be deleted. Additionally, regarding affix reduction in the word-final position, all subjects seemed to depend on this articulatory strategy to a similar degree. In sum, the current study found that affixes without primary semantic content in spontaneous speech tend to undergo the process of reduction, favoring the occurrence of specific pronunciation variants.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.1
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• pp.20-26
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• 2013

Image noise reduction in the frequency domain by thresholding is simple, but quite effective. Wavelet domain thresholding has been an active area of research but relatively little work has been published on DCT domain denoising. A novel method for determining the hard threshold for the DCT domain denoising is proposed. The low amplitude DCT coefficients are discarded until the cumulative sum of the discarded signal energy is comparable to that of noise in each DCT block. Cycle spinning is also applied to reduce block artifacts. The proposed method is quite effective and simple enough to be used in portable devices.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.445-454
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• 2006

We describe a solution to the Ornstein-Uhlenbeck equation $\frac{dI}{dt}-\frac{1}{\tau}$I(t)=cV(t) where V(t) is a constant multiple of a Gaussian white noise. Our solution is based on a discrete set of Gaussian white noise obtained by taking sample points from a sum of single frequency harmonics that have random amplitudes, random frequencies, and random phases. Hence, it is different from the solution by the standard random walk using random numbers generated by the Box-Mueller algorithm. We prove that the power of the signal has the additive property, from which we derive that the Lyapunov characteristic exponent for our solution is positive. This compares with the solution by other methods where the noise is kept to be in an error range so that its Lyapunov exponent is negative.

• Journal of applied mathematics & informatics
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• v.26 no.5_6
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• pp.973-981
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• 2008

In this paper we focus on a type of Unimodular polynomial pair used for digital systems and present some new properties of them which lead us to estimation of their autocorrelation coefficients and the moments of a Rudin-Shapiro polynomial product. Some new results on the Rudin-shapiro sequences will be presented in the last section. Main Facts: For positive integers M and n with $M\;<\;2^n$ - 1, consider the $2^n$ - M numbers ${\epsilon}_k$ ($M\;{\leq}\;k\;{\leq}\;2^n$ - 1) which form a collection of Rudin-Shapiro coefficients. We verify that $|{\sum}_{k=M}^{2^{n-1}}\;{{\epsilon}_k}e^{ikt}|$ is dominated by $(2+\sqrt{2})\;\sqrt {2^n-M}-{\sqrt{2}}$.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.281-283
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• 1999

This topic presents an inductor short turn testing. From the rudimentary principles, the quality factor(Q) decreases due to inductor short turn. Frequency response varies because of the variation of circuit inductance and resistance. In general, short turn circuit testing is performed by comparing the ratio of an inductance and resistance of inductor in that particular circuit. An alternative method can be done by considering the response of second order circuit which can give both dynamic and static testing, whereas static testing give an error results not more than 2 turns. For dynamic testing, the result is more accurate, which can test fur the short turn number form 1 turn onward.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1735-1738
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• 2003

영상은 주파수 분포로 볼 때, 크게 에지 영역과 평탄 영역으로 구분할 수 있다. 또한 각 영역 안에서도 다양한 주파수 분포를 가지고 있다. 기존의 가중치 합(weighted-sum)기반의 방법으로는 다양한 주파수 변화를 포괄하기가 어렵고, 특히 고주파 성분을 효과적으로 보전할 수 없다. 이런 문제를 해결하기 위해서 본 논문에서는 영상의 국부 영역의 주파수 특성에 기반을 둔 deinterlacing 방법을 제안한다. 제안 방법에서는 우선 영상을 에지 영역과 평탄 영역으로 구분하였다. 그런 다음, 각 영역에 대해 신경 회로망을 할당하였다. 또한 각 영역에 대해서 저주파 성분과 고주파 성분으로 모듈화된 신경 회로망을 사용하여 각 영역 안에서의 주파수 특성의 변화에 잘 반응할 수 있게 하였다. 모의 실험에서 제안 알고리즘은 단일 신경 회로망의 경우나 기존의 다른 알고리즘들보다 개선된 성능을 보여주었다

• The Journal of the Acoustical Society of Korea
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• v.15 no.2
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• pp.101-104
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• 1996

The pressure field for the Pekeris model which is consisted of a surface layer of fresh water overlying a thick (essentially semi-infinite) bottom layer of coarse sand is investigated experimentally in a anechoic tank scaled down 1/1,000. The water depth and frequency have been controlled so that the continuous mode integrand has not a resonance close to cut-off, and the experimental results relatively well agree with the theory which is represented as the sum of the discrete modes over a range about 10 times the water depth.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.129-133
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• 2012

Coordinated multi-point transmission (CoMP) is a candidate technique for next generation cellular communications systems. One of the primary elements discussed in LTE-Advanced technology is CoMP, which can improve cell edge user data rate as well as spectral efficiency due to multiple input multiple output - orthogonal frequency division multiplex (MIMO-OFDM). We consider a system with multiple cells in which base stations coordinate with each other by sharing user channel state information (CSI), which mitigates inter cell interference (ICI), especially for users located at the cell edge. We introduce a new user scheduling method of ICI cancellation and the loss reduction of effective channel gain during the beamforming process, the proposed method improves the system sum rate, when compared to the conventional method by an average of 0.55bps/Hz in different number of total users per cell. It also outperforms the conventional method by approximately 0.38bps/Hz using different SNRs.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.567-570
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• 1997

In a conventional digital beamformer received signal were sampled at least Nyquist rate of its maximum frequency. But it is wide band signal and its coherent sum must be obtained, the sampling clock of about $8f_o$ and $16f_o$ is necessary or high quality images. This paper described how image qualities are varied according to sampling clock. Mainly, we compared the SDF(Sampled Delay Focusing) that had maximum precision of $8f_o$ with $16f_o$ sampling system and analyze its characteristics.