• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.402-405
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• 1997

The analysis of heart sounds is a noninvasive diagnostic method useful to diagnose heart valve function. In this paper we compared the ability of spectral analysis method for prosthetic heart valve sounds. Phonocardiograms of prosthetic heart valve were analyzed in order to derive frequency domain feature suitable for the classification of the valve state. The FFT-based methods did not provide sufficient frequency resolution to completely characterize the spectrum of prosthetic heart valve sounds. A high resolution parametric methods were shown to give superior frequency resolution. In parametric methods, all methods provide a 1st & 2nd & 3rd frequency component. But Shank method provided a most dominant frequency peak.

• 천문학회보
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• 제36권2호
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• pp.154.1-154.1
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• 2011

IGRINS (Immersion Grating Infrared Spectrometer) is a cross-dispersed high resolution near-infrared spectrograph whose primary disperser is a silicon immersion grating (SIG) and cross-dispersers are two volume phase holographic gratings (VPHG). IGRINS covers the full ranges of H and K astronomical wavelength bands at a single exposure with the spectral resolution of 40,000. The overall layout of the IGRINS Cryostat is a $960{\times}600{\times}380$ cubic millimeter rectangular box and the whole optical train is sitting on an $880{\times}520{\times}50\;mm^3$ rectangular Optical Bench. The total volume of the instrument has been revolutionarily reduced and remained compact for the spectral coverage and sensitivity of a high resolution spectrograph in infrared. We, in this presentation, introduce the design models, the structural and thermal analysis results of the mechanics and cryogenics of IGRINS.

• 한국통신학회논문지
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• 제21권2호
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• pp.340-346
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• 1996

In this paper, we propose a ne weighted backward covariance matrix method to enhance the resolution for direction-of-arrival(DOA) estimation. The proposed method (MEVM:modified eigenvector method) is an enhanced covariance matrix method which is an extended form of the conventional covariance matrix. We analyze the effect of using the weighted forward-baskward covariance matrix on the performance of the eigenvector method(EVM). By comparing the perturbation angle of the noise-subspace, we show that the spectral estimate obtained using the proposed method is less distorted than the spectral estimate obtained using the conventional EVM. The simulation results show that the new method is more accurate and has better resolution than the conventional EVM under the same noise conditions.

• 대한원격탐사학회지
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• 제35권6_2호
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• pp.1095-1106
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• 2019

산불 피해는 복구, 보상 및 2차 피해 예방을 위해 빠르고 정확히 조사되어야 한다. 원격탐사 기반의 산불 피해강도 조사 방법으로 주로 산불 전과 후의 반사율 및 분광지수의 차이를 비교하고 있다. 최근 고해상도 위성영상 및 무인기 영상의 활용이 증가하고 있으나, 언제 어디에서 발생할지 예측할 수 없는 산불에 대한 발생 전 영상을 획득하는 것이 쉽지 않다. 본 연구에서는 산불 피해강도 분류에 있어 고해상도 영상과 감독분류 기법의 활용 가능성을 분석하고자 하였다. 산불 후에 촬영된 KOMPSAT-3A 영상과 무인기 다중분광영상에 반사율의 절대값을 이용하는 최대우도법과 반사율의 패턴을 이용하는 분광각매퍼의 두 가지 감독분류 기법을 적용하였다. 그 결과 분류 기법 측면에서 최대우도법이 분광각매퍼에 비해 높은 분류정확도를 보여주었으며, 이는 피해강도 등급 간에 분광반사율의 절대값은 다르지만 패턴이 유사한 등급들이 존재하기 때문인 것으로 판단된다. 공간해상도 측면에서 상대적으로 해상도가 높은 무인기 영상의 분류정확도가 위성영상보다 높게 나타났다. 그러나 무인기와 위성 영상 모두 분류정확도가 매우 높게 나타나고 있어 피해강도 분류에 활용 가능성이 높다고 할 수 있다. 따라서, 피해강도 분류에 있어 산불 후에 촬영된 고해상도 영상들을 이용할 수 있을 것으로 판단된다.

• 천문학회보
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• 제40권2호
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• pp.58.2-58.2
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• 2015

We present a library of high spectral resolution (R ~ 40,000) and high signal-to-noise ratio (S/N ~ 200) near-infrared spectra of ~50 late-type stars. The spectra of late-type stars were obtained with Immersion GRating INfrared Spectrograph (IGRINS) covering the full H and K band. The stars are mainly from MK standard stars which have well-defined spectral types and luminosity classes and cover wide ranges of effective temperatures and surface gravities. The spectra are corrected for telluric absorption lines and absolutely flux calibrated using the Two Micron All Sky Survey (2MASS) photometry. In this work, we present the preliminary results of spectroscopic diagnostics for stellar physical parameters. Our ultimate goal is to provide a library of near-infrared spectra of standard stars, which covers all spectral types and luminosity classes, with a high spectral resolution and high signal-to-noise ratio.

• 한국음향학회지
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• 제16권5호
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• pp.83-91
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• 1997

원자로의 구조적 건전성을 확보하고 사고를 미연에 방지하기 위해서 중성자 잡음 신호를 이용한 진동 감시에는 주기성 도표(periodogram), 평균주기성도표(averaged periodobram), Blackman-Tukey 스펙트럼 추정 등을 이용하고 있으나 본 논문에서는 통계적인 비편향성(unbaised), 일치성(consistency), 효율성(efficiency), 충족성(minimum lower bound)을 고려한 파라미터 모델링 방법 중 AR 모델을 이용하여 원자로 구조물의 최적의 파라미터를 추정하고 진동 감시에 필요한 스펙트럼 분석의 해상도를 높였다. 특히 논문에서는 차수 선정에서 AR 모델의 적절한 차수선정(order selection)을 위하여 자기상관의 lag value을 이용하였다. AR 방법중 Burg 방법이 원자로 구조물의 고유진동수를 추적하는데 가장 효과적이다.

• 응용통계연구
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• 제22권3호
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• pp.499-513
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• 2009

An economic signal in the real world usually reflects complex phenomena. One may have difficulty both extracting and interpreting information embedded in such a signal. A natural way to reduce complexity is to decompose the original signal into several simple components, and then analyze each component. Spectral analysis (Priestley, 1981) provides a tool to analyze such signals under the assumption that the time series is stationary. However when the signal is subject to non-stationary and nonlinear characteristics such as amplitude and frequency modulation along time scale, spectral analysis is not suitable. Huang et al. (1998b, 1999) proposed a data-adaptive decomposition method called empirical mode decomposition and then applied Hilbert spectral analysis to decomposed signals called intrinsic mode function. Huang et al. (1998b, 1999) named this two step procedure the Hilbert-Huang transform(HHT). Because of its robustness in the presence of nonlinearity and non-stationarity, HHT has been used in various fields. In this paper, we discuss the applications of the HHT and demonstrate its promising potential for non-stationary financial time series data provided through a Korean stock price index.

• 천문학회보
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• 제41권1호
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• pp.44.1-44.1
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• 2016

In this paper, we present a catalogue of the spectra of bright stars observed during the sky survey using the Far-Ultraviolet Imaging Spectrograph (FIMS), which was designed primarily to observe diffuse emissions. By carefully eliminating the contamination from the diffuse background, we obtain the spectra of 70 bright stars observed for the first time with a spectral resolution of $2-3{\AA}$ over the wavelength of $1370-1710{\AA}$. The far-ultraviolet spectra of an additional 139 stars are also extracted with a better spectral resolution and/or higher reliability than those of the previous observations. The stellar spectral type of the stars presented in the catalogue spans from O9 to A3. The method of spectral extraction of the bright stars is validated by comparing the spectra of 323 stars with those of the International Ultraviolet Explorer (IUE) observations.

• 전기전자학회논문지
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• 제10권2호통권19호
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• pp.116-122
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• 2006

We have built a grating-based, high-resolution, spectral line-by-line pulse shaper. By controlling individual spectral lines of a mode-locked laser output, we demonstrate the interesting functionalities of the pulse shaper for arbitrary waveform generation, such as width tunable pulse generation, phase controlled waveform generation, microwave waveform generation, etc.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.446-450
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• 1987

In this paper, overdetermined method is used for high resolution spectral estimation in case of short data record length. To reduce the computational effort and to obtain recursive form of estimation algorithm, we modify data matrix to have near-Toeplitz structure. Then, new recursive algorithm is derived in the form of fast Kalman algorithm. Two stage procedure is used for the estimation of ARMA parameters. First AR parameters are estimated by using overdetermined modified Yule-walker equation, and then MA parameters are implicitly estimated by estimating numerator spectral coefficients(NS).