• The Transactions of the Korean Institute of Electrical Engineers D
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• 제52권9호
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• pp.547-553
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• 2003

In this paper, we designed the PC-based analyzer of the power spectral density that could estimate the heart rate variability from time series data of R-R interval. The power spectral density estimated that it applied the autoregressive model to the measured electrocardiogram during a short period. Also, the characteristics of the designed analyzer are that it could process of the signal filtering, the generation and recomposition of time series and the feature extraction at the same time. Especially the analyzer reconstructed which applied the lowpass filter of the time series composed by the linear interpolation so as to enhance the signal-to-noise feature. We could estimate the power spectral density that confirmed a variety of power peak with low frequency range and high frequency rang of autonomic nerve by the heart rate variability.

• Korean Journal of Optics and Photonics
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• 제13권6호
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• pp.501-505
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• 2002

We have numerically analysed the effects of the light sourer spectral power distortion in an optical CDMA system using PN codes and FBGI for ultra-fast multi-access optical networks. The interference between two CDMA channels decreases with an increase in the code length and the .simultaneous access number is equal to the code length in the region of 0 to 15% spectral power distortion. As a result, the spectral power distortion with optical spectrum is very important in designing the optical CDMA systems.

• ETRI Journal
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• 제31권3호
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• pp.292-297
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• 2009

The power spectral density of a signal can be estimated most accurately by using a window with a narrow bandwidth and large sidelobe attenuation. Conventional windows generally control these characteristics by only one parameter, so there is a trade-off problem: if the bandwidth is reduced, the sidelobe attenuation is also reduced. To overcome this problem, we propose using a Butterworth window with two control parameters for power spectral density estimation and analyze its characteristics. Simulation results demonstrate that the sidelobe attenuation and the 3 dB bandwidth can be controlled independently. Thus, the trade-off problem between resolution and spectral leakage in the estimated power spectral density can be overcome.

• Progress in Medical Physics
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• 제6권2호
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• pp.103-109
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• 1995

Power spectral analysis of spontaneous heart rate fluctuations were assessed by use of autooic blocking agents and changes in posture. The total power spectral range of interest is divided amongst the various experiments so that each respiratory pattern contributes a spectral ratio of interval to respiration only over a group of frequencies for which the specific respiratory pattern has substantial, and roughly constant, spectral magnitudes. System hardware is consisted ECG preamplifier, respiratory fluctuation detect, interval time generator and IBC 486PC. High frequency fluctuation, at the respiratiory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Power spectral analysis is a powerful nonivsve tool for quantitying autonomic nervous system activity.

• Journal of Korea Multimedia Society
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• 제18권12호
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• pp.1439-1444
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• 2015

Measuring spectral reflectance can be regarded as obtaining inherent color parameters, and spectral reflectance has been used in image processing. Model-based spectrum recovering, one of the method for obtaining spectral reflectance, uses ordinary camera with multiple illuminations. Conventional model-based methods allow to recover spectral reflectance efficiently by using only a few parameters, however it requires some parameters such as power spectrum of illuminations and spectrum sensitivity of camera. In this paper, we propose an enhanced model-based spectrum recovering method without pre-measured parameters: power spectrum of illuminations and spectrum sensitivity of camera. Instead of measuring each parameters, spectral reflectance can be efficiently recovered by estimating and using the spectrum characteristic matrix which contains spectrum parameters: basis function, power spectrum of illumination, and spectrum sensitivity of camera. The spectrum characteristic matrix can be easily estimated using captured images from scenes with color checker under multiple illuminations. Additionally, we suggest fast recovering method preserving positive constraint of spectrum by nonnegative basis function of spectral reflectance. Results of our method showed accurately reconstructed spectral reflectance and fast constrained estimation with unmeasured camera and illumination. As our method could be conducted conveniently, measuring spectral reflectance is expected to be widely used.

• ETRI Journal
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• 제33권1호
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• pp.1-5
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• 2011

Downlink transmit power allocation schemes are proposed for soft fractional frequency reuse (FFR) in loose and tightly coordinated systems. The transmit powers are allocated so that the loss of spectral efficiency from the soft FFR is minimized, and the required cell edge user throughput is guaranteed. The effect of the soft FFR on spectral efficiency is evaluated depending on the power allocation schemes and the number of subbands. Results show that the loss of spectral efficiency from the soft FFR can be reduced by configuring an appropriate number of subbands in the loosely coordinated systems. In tightly coordinated systems, results show that the loss of spectral efficiency can be minimized regardless of the number of subbands due to its fast coordination.

• Journal of the Institute of Electronics and Information Engineers
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• 제50권1호
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• pp.117-123
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• 2013

By calculating the spectral efficiency of symmetric balance incomplete block design(BIBD) codes satisfying BER=$10^{-9}$, it can be found that ideal BIBD code design with m=2 and various q's is effective when effective power is high($P_{sr}=-10$ dBm). But BIBD code design with q > 2 and various m's can be effective when effective power is low($P_{sr}=-25$ dBm).

• Current Optics and Photonics
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• 제7권6호
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• pp.665-672
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• 2023

This study focuses on investigating the impact of the spectral linewidth of a seed laser in a master-oscillator power amplifier (MOPA) configuration on stimulated Brillouin scattering and the beam quality of the output diffracted by a grating. To conduct the study, a distributed feedback (DFB) laser is modulated in a pseudorandom binary sequence (PRBS) and amplified by a two-stage Yb-doped fiber amplifier to achieve an output power of over 1 kW. The spectral linewidth of the seed laser is systematically varied from 1 to 12 GHz in the frequency domain by varying the PRBS modulation parameters. The experimental results reveal a tradeoff between suppressing stimulated Brillouin scattering and enhancing beam quality with increased spectral linewidth. Therefore, the study provides valuable insights into optimizing spectral beam combining to achieve high beam quality and scalable power upgrade in fiber lasers.

• Journal of the Institute of Convergence Signal Processing
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• 제2권2호
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• pp.39-46
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• 2001

In this paper we propose a new method that can be estimation the spectral power distribution of the light source from three-band images. the light source is estimated by dividing the reflected spectral power distribution of the maximum achromatic region(L(λ)) by the corresponding surface reflectance(Ο(λ)). In order to obtain reflected spectral power distribution of the maximum achromatic region from three-bend images, a modified gray world assumption algorithm is adapted. And the maximum surface reflectance is estimated using the principal component analysis method along with achromatic population. The achromatic population is created from a set of given Munsell color chips whose chroma vector is less than threshold. Cumulative contribution ratio of principal components from the first to the third for classified achromatic population was about 99.75%. The reconstruction of illumination spectral power distribution by using achromatic population and three-band digital images captured under various light source was examined, and evaluated by RMSE between the original and reconstructed illumination spectral power distribution. This work was supported by grant No (2000-1-30200-005-3) from the Basic Research Program of the Korea Science & Engineering Foundation.

• Journal of the Ergonomics Society of Korea
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• 제29권5호
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• pp.741-750
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• 2010

The objective of this paper is to study if the EEG spectral relative power would be a reasonable measure of expertise level. EEG electrodes were placed on the locations of Fp1, Fp2, F3, F4, T3, T4, O1, O2 while 5 subjects were playing 4 kinds of game on PC. EEG spectral relative power was significantly related with expertise level on the locations of Fp1, T3, T4, O1, O2. And the results showed that the $\theta$ and $\alpha$ activities were decreased, while $\beta$ and $\gamma$ activities were increased. The results indicated that the EEG spectral relative power would be applicable as a quantitative measure of expertise level.