• 한국안전학회지
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• 제12권4호
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• pp.3-8
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• 1997

This paper shows a performance estimation of windowing a single tone with added Gaussian noise and uniform noise. Signal-to-noise ratio can be determined by the ratio of the output noisy signal variance to the input noisy signal variance of a window. Standard deviation of noise is reduced by windowing Signal-to-noise ratio of the noisy signal is reduced by the windowing operation. Thus, performance of window function can be determined by this filtering operation that improved the signal-to-noise ratio.

• International Journal of Control, Automation, and Systems
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• 제6권6호
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• pp.818-827
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• 2008

In this paper, we propose a new noise estimation and reduction algorithm for stationary and nonstationary noisy environments. This approach uses an algorithm that classifies the speech and noise signal contributions in time-frequency bins. It relies on the ratio of the normalized standard deviation of the noisy power spectrum in time-frequency bins to its average. If the ratio is greater than an adaptive estimator, speech is considered to be present. The propose method uses an auto control parameter for an adaptive estimator to work well in highly nonstationary noisy environments. The auto control parameter is controlled by a linear function using a posteriori signal to noise ratio(SNR) according to the increase or the decrease of the noise level. The estimated clean speech power spectrum is obtained by a modified gain function and the updated noisy power spectrum of the time-frequency bin. This new algorithm has the advantages of much more simplicity and light computational load for estimating the stationary and nonstationary noise environments. The proposed algorithm is superior to conventional methods. To evaluate the algorithm's performance, we test it using the NOIZEUS database, and use the segment signal-to-noise ratio(SNR) and ITU-T P.835 as evaluation criteria.

• 한국조경학회지
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• 제31권2호
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• pp.48-57
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• 2003

The objective of this study is to review and verify whether the functions and effect of roadside trees generally hewn in theory are actually realized in urban roads and how well they are performed if the function and effect are realized. The study was conducted with a focus on 3 functions and effects including roadside tree's urban landscape improvement function (green area visibility ratio), effect of introducing green area within a city, and urban green network building function. The major study results are as follows: First, the average green area visibility ratio of 41 study areas is currently about 25.90%. The green area visibility ratio of commercial area within downtown was lowest among 5 road types. It showed that it is possible to raise the average green area visibility ratio up to 32.49% through roadside tree management and additional plantation. Second, in a section between Paldal Mountain and Suwon City Hall where there is no forest fragments and parks at all, a green area of 4,826 roadside trees represented 2.4% of total area and served as the only linear green area. Third, an analysis of 15 cities in Kyonggi province showed that urban forests are concentrated in outskirts. The suey showed that because forest fragments and parks exist in a form of points in urban areas, roadside trees are the only green areas that link each other and build a network.

• 대한후두음성언어의학회지
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• 제23권2호
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• pp.129-132
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• 2012

Background and Objectives : MPT is directly related to degree of glottal closure. So it is widely used in the assessment of glottal closure with unilateral vocal fold paralysis. But MPT could be influenced not only by glottal closure but also by pulmonary function. So MPT might not reflect glottal closure in UVFP with decreased pulmonary function. The purpose of the study is to evaluate usefulness of MPT and ratio of /s/ time to /z/ time before and after injection laryngoplasty in UVCP with decreased pulmonary function. Materials and Methods : This study involved 34 patients with unilateral vocal fold paralysis : with decreased pulmonary function in group A (n=15) : with normal pulmonary function in group B (n=19). All patients underwent injection laryngoplasty. Paramters of perceptual analysis, acoustic analysis, aerodynamic analysis, videostroboscopy were compared between two groups. Results : Breathness and asthenic scale, G scale of perceptual analysis were significantly improved in both groups. Glottal gap index were significantly decreased after injection in both groups. In aerodynamic analysis, MPT was improved after injection laryngoplasty in both groups, but S/Z ratio was improved only in group B. In correlation analysis, /s/ time was not correlated with pulmonary function. Conclusion : S/Z ratio reflects neither the pulmonary function nor the glottal clousure properly. MPT is more useful indicator than S/Z ratio to evaluate vocal fold paralysis even with decreased pulmonary function.

• Journal of the Korean Data and Information Science Society
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• 제21권4호
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• pp.709-717
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• 2010

연관성 규칙 마이닝은 각 항목들 간의 관련성을 찾아내는 데 활용되며, 지지도, 신뢰도, 향상도 등의 연관성 측도를 기반으로 두 항목간의 관계를 수치화함으로써 의미 있는 규칙을 찾아낸다. 본 논문에서는 조건부 확률 증분비를 이용한 연관성 순위 결정 함수를 제안하고자 한다. 특히 항목 집합간의 고유한 연관성 정도를 제대로 반영하기 위해 조건부 확률 증분비를 이용하여 연관성 순위 결정 함수를 제안하여 3개의 연관기준값들 중 어느 하나라도 기준 이상이 되는 규칙의 순위를 매겨 필요한 연관성 규칙만을 생성할 수 있도록 한다. 모의실험을 해본 결과, 본 논문에서 제안한 함수는 기존의 함수와는 달리 특정 연관 기준값의 영향을 받지 않으며, 최저 연관성 기준값들의 범위와는 관계없이 항상 -1과 1 사이의 값을 가진다는 사실을 확인할 수 있었다. 또한 조건부 확률 증분비를 이용한 연관순위결정 함수는 대체적으로 연관성 측도들과 최저 연관기준값들간의 차이를 잘 반영하고 있는 것으로 나타났다.

• 조명전기설비학회논문지
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• 제26권12호
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• pp.68-73
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• 2012

In this paper, the fault current limiting characteristics of a flux-lock type superconducting fault current limiter (SFCL) with peak current limiting function were analyzed through its short-circuit tests. The setting condition for the peak current limiting operation was derived from its electrical equivalent circuit, which was dependent on the inductance ratio between the third coil and the first coil. Through the analysis on the short-circuit tests for the flux-lock type SFCLs with the different inductance ratio between the third coil and the first coil, the setting value for the peak current limiting operation of the flux-lock type SFCL with peak current limiting function could be confirmed to be adjusted with the variation of the inductance ratio between the third coil and the first coil.

• 한국초전도ㆍ저온공학회논문지
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• 제21권3호
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• pp.1-5
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• 2019

The superconductor stability theories are consistently described by the integral formula. If the defined stability function is a simple decreasing function, it becomes a cryogenic stability condition. If the stability function has a maximum value and a minimum value, and the maximum value is less than 0, then it is a cold-end recovery condition. If the maximum value is more than 0, it can be shown that the unstable equilibrium temperature, that is, the MPZ (minimum propagation zone) temperature distribution can exist. The MPZ region is divided into two regions according to the current ratio. At the low current ratio, the maximum dimensionless temperature is greater than 1, and at the relatively high current ratio, the maximum dimensionless temperature is less than 1. In order to predict the minimum quench energy, the dimensionless energy was obtained for the MPZ temperature distribution. In particular, it was shown that the dimensionless energy can be obtained even when the MPZ maximum temperature is 1 or more.

• 한국정밀공학회지
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• 제15권12호
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• pp.97-105
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• 1998

The fiber oriented condition inside fiber reinforced composite material is a basic factor of mechanical properties of composite materials. It is very important to meausure the fiber orientation angle for the determination of molding conditions, mechanical characteristics, and the design of composite materials. In the work, the fiber orientation distribution of simulation figure plotted by PC is measured using image processing in order to examine the accuracy of intersection counting method. The fiber orientation function measured by intersection counting method using image processing is compared with the calculated fiber orientation function. The results show that the measured value of fiber orientation function using intersection counting method is lower than the calculated value, because the number of intersection between the scanning line and the fiber with smaller fiber aspect ratio is counted less than with larger fiber aspect ratio.

• Journal of Communications and Networks
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• 제18권1호
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• pp.19-26
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• 2016

In this paper, the performance of dual-hop multi-relay maximum ratio transmission (MRT) over Rayleigh flat fading channels is studied with both conventional (all relays participate the transmission) and opportunistic (best relay is selected to maximize the received signal-to-noise ratio (SNR)) relaying. Performance analysis starts with the derivation of the probability density function, cumulative distribution function and moment generating function of the SNR. Then, both approximate and asymptotic expressions of symbol error rate (SER) and outage probability are derived for arbitrary numbers of antennas and relays. With the help of asymptotic SER and outage probability, diversity and array gains are obtained. In addition, impact of imperfect channel estimations is investigated and optimum power allocation factors for source and relay are calculated. Our analytical findings are validated by numerical examples which indicate that multi-relay MRT can be a low complexity and reliable option in cooperative networks.

• 대한물리의학회지
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• 제14권1호
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• pp.25-33
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• 2019

PURPOSE: This study examined the effective impact of self and resistive and ultrasound-biofeedback diaphragm breathing on the pulmonary function and diaphragm thickening ratio of young adults. METHODS: Thirty normal adults were assigned randomly to three experimental groups (self- diaphragm breathing (n=9), resistive-diaphragm breathing (n=11), ultrasound-biofeedback diaphragm breathing (n=10)). Each group participated for 15 minutes for times with a two minute rest between two sets. The subjects were assessed using the pre- and post- diaphragm thickening ratio and the pulmonary function (forced vital capacity, forced expiratory volume at one second, maximal voluntary ventilation, and respiratory rate) on the thirty subjects. A paired t-test was to determine the difference between before and after the experiment in each group of diaphragm breathing before and after the exercises. One-way ANOVA was used to determine the differences between the groups. RESULTS: The forced vital capacity and maximal voluntary ventilation measurements revealed a significant difference in the resistive-diaphragm breathing group than the other two groups. On the other hand, there was no significant difference between the self-diaphragm breathing and ultrasound-biofeedback breathing groups. CONCLUSION: The resistive-diaphragm breathing group showed greater improvement in the pulmonary function than the other two groups. Therefore, resistive-diaphragm breathing will improve the pulmonary function on normal young adults.