• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.748-750
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• 1999

In this study, a speech enhancement is presented based on the utilization of well-known auditory mechanism, noise masking. The speech enhancement approach adopted here is to derive an modifier that achieves audible noise suppression. This modification selectively affects the perceptually significant spectral values, and is therefore less prone to introduction of unwanted distortions than methods that affect the complete STSA and produces more enhanced results at low SNR as well as at high SNR. The speech enhancement method adopted here needs exact estimation of the minimum specteal value per critical band because it uses only the minimum spectral value per critical band. For this, the method adopted here uses the modified spectral subtraction that is more flexible than power spectral subtraction. So, the result in experiment represented better SNR than before.

• Journal of Communications and Networks
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• 제16권6호
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• pp.600-612
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• 2014

In this paper, we consider the problem of spectrum sensing for advanced television systems committee (ATSC) digital television (DTV) signal detection. To exploit the cyclostationarity of the ATSC DTV signals, we employ spectral correlation density (SCD) as the decision statistic and propose an optimal detection algorithm. The major difficulty is in obtaining the probability distribution functions of the SCD. To overcome the difficulty, we probabilistically model the pilot frequency location and employ Gaussian approximation for the SCD distribution. Then, we obtain a practically implementable detection algorithm that outperforms the industry leading systems by 2-3 dB. We also propose various techniques that greatly reduce the system complexity with performance degradation by only a few tenths of decibels. Finally, we show how robust the system is to the estimation errors of the noise power spectral density level and the probability distribution of the pilot frequency location.

• 한국인쇄학회:학술대회논문집
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• 한국인쇄학회 1998년도 추계 논문 발표회 논문집
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• pp.16-21
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• 1998

Spectral reflrectance of the object should be mesured to predict the color of object under various illuminants. The spectral reflectance can be represented in a multidemensional space; Generally we can obtain only three-channel data from input device such as CCD camera, color scanner etc. The estimation from three dimernsional to multidimension can be achieved using principal components of spectral reflectance. In this paper, A method to predict the spectral reflectance of skin color taken by 3-channel input device is discribed. To confirm this method, we simulate color represent under various illuminants about yellow, white and colored women face.

• 한국정보통신학회논문지
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• 제14권4호
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• pp.959-966
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• 2010

정량적 초음파 분석(Quantitative Ultrasound Analysis)은 반향된 초음파 신호의 짧은 시간 간격의 주파수 성분을 추출하여 개별 초음파 지수의 값을 예측한다. 따라서 반향 신호의 정확한 주파수 특성 추출은 분석의 정확도와 정밀도 향상에 기본이 된다. 본 논문에서는 초음파 지수의 정량적인 예측 및 분석에 이용할 수 있는, 짧은 시간 간격의 반향 신호의 주파수 특성 추출 방법을 제안한다. 제안된 알고리듬은 인접한 반향 초음파 신호간의 위상 차이를 보상하고, 동일 반향 깊이를 가지는 작은 영역의 신호를 가중치 평균함으로써 보다 정확한 주파수 특성을 추출한다. 컴퓨터 모의 실험을 통한 수치 분석 결과, 제안된 알고리듬은 일반적인 주파수 추출 알고리듬보다 정확한 예측 결과를 보였으며, 예측 결과의 정밀도도 10% 이상 향상되었다.

• 대한전자공학회논문지SP
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• 제38권4호
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• pp.392-400
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• 2001

본 논문에서는 단일 영상에 포함된 광원의 분광분포를 추정하는 광원추정 알고리즘을 제안한다. 제안된 광원 추정 방법은 두 단계로 이루어져 있다. 첫째, 변형된 회색계 가정(modified gray world assumption)을 이용하여 부분적으로 광원의 영향을 배제한 후 밝으면서도 무채색에 가까운 최대 무채색 영역을 찾아 그 영역의 표면 분광 반사율을 구한다. 이때 최대 무채색 영역의 표면 분광 반사율은 1269개의 Munsell 색 표본에 대하여 주성분 분석 방법을 이용하여 추정하였다. 둘째, 주어진 Munsell 색 표본과 대표 광원의 조합으로 반사광의 모집단을 만들었다. 다음 최대 무채색 영역의 각 화소와 반사광 모집단과의 색차를 비교하여 최대 무채색 영역과 색차가 가장 적은 반사광 표본을 선택하고 이를 최대 무채색 영역에 대한 반사광의 분광분포로 정의한다. 최종적으로 최저 무채색 영역의 반사광 분광분포를 해당하는 표면 분광반사율로 나누어줌으로써 영상에 포함된 광원의 분광분포를 추정한다. 제안한 알고리듬의 성능을 평가하기 위하여 유색 광원에 조명된 영상에 대한 광원 추정 실험을 하였으며 기존의 방법과 추정된 광원의 분광 분포 비교 및 색차 비교를 통해 그 타당성을 검증하였다.

• Earthquakes and Structures
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• 제5권4호
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• pp.439-459
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• 2013

Main objective of the present study is to determine the statistical properties and suitable probability distribution functions of spectral displacements from nonlinear static and nonlinear dynamic analysis within the frame work of Monte Carlo simulation for typical low rise and high rise RC framed buildings located in zone III and zone V and designed as per Indian seismic codes. Probabilistic analysis of spectral displacement is useful for strength assessment and loss estimation. To the author's knowledge, no study is reported in literature on comparison of spectral displacement including the uncertainties in capacity and demand in Indian context. In the present study, uncertainties in capacity of the building is modeled by choosing cross sectional dimensions of beams and columns, density and compressive strength of concrete, yield strength and elastic modulus of steel and, live load as random variables. Uncertainty in demand is modeled by choosing peak ground acceleration (PGA) as a random variable. Nonlinear static analysis (NSA) and nonlinear dynamic analysis (NDA) are carried out for typical low rise and high rise reinforced concrete framed buildings using IDARC 2D computer program with the random sample input parameters. Statistical properties are obtained for spectral displacements corresponding to performance point from NSA and maximum absolute roof displacement from NDA and suitable probability distribution functions viz., normal, Weibull, lognormal are examined for goodness-of-fit. From the hypothesis test for goodness-of-fit, lognormal function is found to be suitable to represent the statistical variation of spectral displacement obtained from NSA and NDA.

• 한국농공학회논문집
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• 제51권3호
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• pp.37-43
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• 2009

The objective of this study was to investigate the basic relationships between spectral reflectance and varying concentrations of sediment in surface waters. An experimental method for determining suspended sediment concentration (SSC) in the water by use of a spectroradiometer above the water surface, in visible and near-infrared (NIR) wavelengths, is applied. The main advantage of the method is the direct comparison of spectral reflectance and the SSC, but it requires an accurate knowledge of the water body and sediment. Therefore numerous spectroradiometric measurements are carried out in situ measurements, for SSC, ranging from zero to 100 percentage and two types of sediment applied in the water tank. The results indicate that the suspended sediment causes increasing spectral reflectance response in waters. We observed that spectral reflectance increases with SSC, first at the lower wavelengths (430-480 nm), then in the middle wavelengths (570-700 nm), and finally, in the NIR domain (800-820 nm); a characteristic maximum reflectance appears at 400-670 nm. Relationships between the wavelength, integral value, and the SSC were evaluated on the basis of the regression analysis. The regression curve for the relation between the wavelength, integral value, and the SSC were determined ($R^2$>0.98). Finally, the specular wavelength can be estimated to recognize the sediment and to improve SC estimation accuracy in the water.

• 한국음향학회지
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• 제36권1호
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• pp.64-69
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• 2017

본 논문에서는 PTT(Push-To-Talk) 기반의 무선 통신을 위한 진폭 및 위상 복원 기반의 단일 채널 음성 향상 방식을 제안한다. 제안한 방식은 신호의 진폭만을 대상으로 음성 향상을 진행했던 기존의 방식들과 달리, 음성 신호의 진폭과 위상을 분리하여 각각 향상시켜 다시 결합함으로써 더욱 양질의 음성을 제공한다. 본 논문에서 제안하는 방식의 성능을 평가하기 위해 동적 잡음 환경에서의 단계별 비교 실험을 실시하였으며, 실험 결과를 통해 제안한 방식이 다양한 잡음 환경에서 양질의 음성을 제공하는 것을 확인할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권7호
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• pp.2879-2890
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• 2020

In this paper, we study the estimation of angle, range and polarization parameters of a bistatic polarization sensitive frequency diverse array multiple-input multiple-output (PSFDA-MIMO) radar system. The application of polarization sensitive array in receiver is explored. A signal model of bistatic PSFDA-MIMO radar system is established. In order to utilize the multi-dimensional structure of array signals, the matched filtering radar data can be represented by a third-order tensor model. A joint estimation of the direction-of-departure (DOD), direction-of-arrival (DOA), range and polarization parameters based on parallel factor (PARAFAC) algorithm is proposed. The proposed algorithm does not need to search spectral peaks and singular value decomposition, and can obtain automatic pairing estimation. The method was compared with the existing methods, and the results show that the performance of the method is better. Therefore, the accuracy of the parameter estimation is further improved.

• 한국군사과학기술학회지
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• 제18권3호
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• pp.253-259
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• 2015

This paper introduces a signal processing technique for discrimination of missile target. In order to detect and discriminate the target, a seeker radar makes use of chirp waveform and stretch processing to generate high resolution range profiles(HRRPs). RELAX(relaxation) algorithm, which is one of the spectral estimation techniques, was used to find scattering centers of a missile from HRRP. From the information on the distribution of one-dimensional(1-D) scattering centers on a target, we can discriminate the target without noise.