• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권11호
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• pp.568-574
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• 2001

This paper describes a current fed high frequency resonant inverter can be used as the power supply for wax-sealing. This circuit configuration is composed of conventional two unit inverter of single ended current find type in parallel. The proposed inverter can realize ZVS operation by using resonant capacitor to ZVS capacitor and has merits not only reduction of switch current distribution but also extension of load range in comparison with the conventional single-ended current fed high frequency resonant inverter. This analysis of proposed circuit uses normalized parameter and characteristic estimation which is needed in each step before design is generally described according to normalized frequency($\mu$), normalized resistance(λ) and parameters. On the basis of characteristic values, a method of the circuit design is presented. Also, the theoretical analysis is proved through experiment and this proposed circuit shows that it can be practically used as the power supply system for wax-sealing and DC-DC converter.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권12호
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• pp.4567-4583
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• 2021

This study proposes an analytical approximation algorithm based on extreme value theory (EVT) for the inverse of the power of the incomplete Gamma function. First, the Gumbel function is used to approximate the power of the incomplete Gamma function, and the corresponding inverse problem is transformed into the inversion of an exponential function. Then, using the tail equivalence theorem, the normalized coefficient of the general Weibull distribution function is employed to replace the normalized coefficient of the random variable following a Gamma distribution, and the approximate closed form solution is obtained. The effects of equation parameters on the algorithm performance are evaluated through simulation analysis under various conditions, and the performance of this algorithm is compared to those of the Newton iterative algorithm and other existing approximate analytical algorithms. The proposed algorithm exhibits good approximation performance under appropriate parameter settings. Finally, the performance of this method is evaluated by calculating the thresholds of space-time block coding and space-frequency block coding pattern recognition in multiple-input and multiple-output orthogonal frequency division multiplexing. The analytical approximation method can be applied to other related situations involving the maximum statistics of independent and identically distributed random variables following Gamma distributions.

• Journal of Communications and Networks
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• 제9권1호
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• pp.18-27
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• 2007

The conventional normalized least mean square (NLMS) algorithm is the most widely used for adaptive identification within a non-stationary input context. The convergence of the NLMS algorithm is independent of environmental changes. However, its steady state performance is impaired during input sequences with low dynamics. In this paper, we propose a new NLMS algorithm which is, in the steady state, insensitive to the time variations of the input dynamics. The square soot (SR)-NLMS algorithm is based on a normalization of the LMS adaptive filter input by the Euclidean norm of the tap-input. The tap-input power of the SR-NLMS adaptive filter is then equal to one even during sequences with low dynamics. Therefore, the amplification of the observation noise power by the tap-input power is cancelled in the misadjustment time evolution. The harmful effect of the low dynamics input sequences, on the steady state performance of the LMS adaptive filter are then reduced. In addition, the square root normalized input is more stationary than the base input. Therefore, the robustness of LMS adaptive filter with respect to the input non stationarity is enhanced. A performance analysis of the first- and the second-order statistic behavior of the proposed SR-NLMS adaptive filter is carried out. In particular, an analytical expression of the step size ensuring stability and mean convergence is derived. In addition, the results of an experimental study demonstrating the good performance of the SR-NLMS algorithm are given. A comparison of these results with those obtained from a standard NLMS algorithm, is performed. It is shown that, within a non-stationary input context, the SR-NLMS algorithm exhibits better performance than the NLMS algorithm.

• 한국콘텐츠학회논문지
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• 제6권12호
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• pp.89-95
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• 2006

독립성분분석을 사용한 암묵신호분리의 성능은 잔향이 존재하는 환경에서 잔류 누설 성분 (cross-talk) 때문에 현저히 저하된다. 본 논문에서는 잔류 누설 성분을 제거하기 위한 후처리 방법을 제안한다. 제안하는 방법은 주파수 영역에서의 변형된 NLMS(normalized least mean square) 필터를 사용하며 필터의 역할은 잔류 누설 성분을 유발하는 누설 경로를 추정하는 데 있다. 특정 채널에서 잔류하는 누설 성분은 상대 채널의 직접 성분에 해당되므로 관측되는 상대 채널의 입력신호를 이용하여 누설 경로를 추정할 수 있다. 변형된 NLMS 필터는 필터 입력 신호의 전력과 추정 오차 신호의 전력을 함께 고려하여 정규화한다. 특정 채널의 직접 신호 성분은 적응 필터에서 잡음처럼 동작하여 결국 적응필터가 오조정되기 때문에 제안하는 방법을 통해 적응필터의 오조정을 방지할 수 있다. 음성 신호를 사용한 컴퓨터 시뮬레이션 결과를 통해 제안하는 방법이 후처리를 사용하지 않은 경우에 비해 잡음 제거 성능(NRR)이 약 3dB 정도 개선되는 것을 확인 할 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.593-596
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• 1992

An evaluation method for the effective length of electromagnet - which bas U-shape in frontview and trapezoidal in side view - is presented. Using 2D FEM, 2 analysing models are introduced for calculating effective length of the magnet ; the front model is using the normalized equi-pole face area of the magnet and the side model using the normalized equi-magnetic circuit. The ratio of the effective length to the length of bottom plate (core) comes out 1.25 - 1.30. In addition, 3D FEM analysis has been done and a proto-type test model is manufactured to verify the analysing method. The ratio by the experiment appears 1.2, which is reasonably in good agreement with the suggested numerical results.

• The Journal of the Acoustical Society of Korea
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• 제27권1E호
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• pp.1-10
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• 2008

A noise suppression algorithm is proposed for nonstationary noisy environments. The proposed algorithm is different from the conventional approaches such as the spectral subtraction algorithm and the minimum statistics noise estimation algorithm in that it classifies speech and noise signals in time-frequency bins. It calculates the ratio of the variance of the noisy power spectrum in time-frequency bins to its normalized time-frequency average. If the ratio is greater than an adaptive threshold, speech is considered to be present. Our adaptive algorithm tracks the threshold and controls the trade-off between residual noise and distortion. 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 simplicity and light computational load for estimating the noise. This algorithm reduces the residual noise significantly, and is superior to the conventional methods.

• Journal of Acupuncture Research
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• 제22권6호
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• pp.173-180
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• 2005

Objectives : The purpose of this study was to assess the effect auricular acupuncture for acute mental stress using power spectrum analysis of the heart rate variability(HRV). Methods : 10 healthy volunteers participated in this study. After 5 minute rest, the first mental stress was provided for 5 minute. And then subjects rested for 15 minute. The second mental stress was provided for 5 minute. The acupoint, Shin-Mun point of the ear was stimulated for 15 minute. HRV was recorded before and after the first and second mental stress, and after auricular acupuncture stimulation. Results : After mental stress, normalized LF and LF/HF ratio is significantly increased. Before and after simple rest, normalized LF and normalized HF is significantly changed, but LF and LF/HF ratio is not significantly changed. On the other hand, before and after auricular acupuncture treatment, normalized LF, normalized HF is significantly changed, and also LF and LF/HF ratio is significantly decreased. Conclusion : The result suggest that auricular acupuncture can decrease more significantly in cardiac sympathetic activity due to mental stress than simple rest.

• 한국음향학회지
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• 제13권6호
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• pp.66-74
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• 1994

잔향음이 우세한 환경하에서 소나 시스템의 성능을 평가할 때 대부분의 음향 모델인 음압 준위(power level) 모델에 비해 수중 잔향음 신호 모의 모델은 매우 유용하게 이용된다. 본 논문에서는 소나 시험에 필요한 잔향음 신호(reverberation time series)를 모의하였다. 우선 주파수 영역에서 밴드의 폭이 변하고 가우시안 분포(Gaussian distribution)를 갖는 표준화된 스펙트럼(normalized spectrum)을 수신 시간 간격에 따라 구하였다. 두번째로, 기존의 음향 모델의 결과인 시간에 따른 잔향음 준위를 각각의 표준화된 스펙트럼의 준위와 합성하였다. 마지막으로 음원 신호의 스펙트럼과 잔향음 스펙트럼을 곱(product)하고 이 결과를 역푸리에 변환(inverse Fourier transform)을 이용하여 신호를 모의하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.225-230
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• 2000

This paper describes a double-ended current fed push-pull type high frequency resonant inverter used as the power supply for wax-sealing. The proposed inverter can realize ZVS operation by using resonant capacitor to ZVS capacitor and has some merits not only reduction of switch current distribution but also extension of load range compare to the conventional single-ended current fed push-pull type high frequency resonant inverter. This analysis of proposed circuit uses normalized parameter ad characteristic estimation which is needed in each step before design is generally described according to normalized frequency($\mu$), normalized resistance(λ) and parameters. It is also presented as an example of method of the circuit design based on estimation analysis values from theoretical analysis. The theoretical analysis is proved through experiment and this circuit shows that it can be used practically as the power supply system for wax-sealing and DC-DC converter.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.682-685
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• 2004

This paper investigated a method for classifying emotional states by using pulse wave signal. It focused on finding effective features for emotional state classification. The emptional states considered here consisted of interest and neutral. Classification experiments utilized 65 and 60 samples of interest and neutral states respectively. We have investigated 19 features derived from pulse wave signals by using both time domain and frequency domain analysis methods with 2 classifiers of minimum distance (normalized Euclidean distanece) and ${\kappa}$-Nearest Neighbour. The Leave-one-out cross validation was used as an evaluation mehtod. Based on experimental results, the most efficient features were a combination of 4 features consisting of (i) the mean of the first differences of the smoothed pulse rate time series signal, (ii) the mean of absolute values of the second differences of thel normalized interbeat intervals, (iii) the root mean square successive difference, and (iv) the power in high frequency range in normalized unit, which provided 80.8% average accuracy with ${\kappa}$-Nearest Neighbour classifier.