• 한국항공우주학회지
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• 제46권3호
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• pp.244-250
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• 2018

다변측정감시시스템은 탑재 트랜스폰더에서 전송되는 신호를 지상에 설치된 여러 수신기에서 획득하고 각각의 수신기의 신호 획득시간의 차를 이용하여 표적의 위치를 계산한다. TDOA(Time Difference Of Arrival) 계산 방법을 이용하는 다변측정감시시스템의 위치 정확도에 가장 큰 영향을 주는 요소 중 하나는 신호 입력 시각 측정 시 발생하는 오차이다. 수신기에서 신호 입력 시각을 측정할 경우 수신기의 기준 클럭을 이용하여 입력 신호를 샘플링하고 동일한 샘플링 레이트를 가지는 기준 샘플(Reference Sample)을 Cross Correlation 기법에 적용한다. 따라서 신호 입력 시각의 정밀도는 기준 클럭에 비례한다. 본 논문에서는 기준 샘플과 이를 샘플링 레이트보다 작은 시간으로 기준 샘플을 지연시킨 다수의 샘플(DRS, Delayed Reference Sample)을 수신기의 입력신호와 Cross Correlation을 수행하여 신호 입력 시각을 보다 정밀하게 측정하기 위한 알고리즘을 제안하였다. 이를 검증하기 위해 Matlab을 이용하여 타겟에서 송출하는 트랜스폰더의 펄스 신호를 구현하였으며 시뮬레이션을 통해 제안한 DRS와 입력신호와의 Cross Correlation을 수행하였다. 이 결과로 부터 신호 입력 시각 정밀 측정의 성능을 분석하였다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1993년도 학술논문발표회 논문집 제12권 1호
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• pp.210-214
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• 1993

There are two general techniques to observe particle movements in fluid. One is the acoustic time domain correlation technique and another is the frequency domain Doppler-shift techniques. Both techniques were reviewed and mentioned their some merits and demerits in ocean wave and current observation. Some possible application of acoustic time domain correlation technique in ocean wind wave measurement was discussed.

• ETRI Journal
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• 제36권1호
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• pp.99-105
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• 2014

This paper presents a new locomotion mode recognition method based on a transformed correlation feature analysis using an electromyography (EMG) pattern. Each movement is recognized using six weighted subcorrelation filters, which are applied to the correlation feature analysis through the use of six time-domain features. The proposed method has a high recognition rate because it reflects the importance of the different features according to the movements and thereby enables one to recognize real-time EMG patterns, owing to the rapid execution of the correlation feature analysis. The experiment results show that the discriminating power of the proposed method is 85.89% (${\pm}2.5$) when walking on a level surface, 96.47% (${\pm}0.9$) when going up stairs, and 96.37% (${\pm}1.3$) when going down stairs for given normal movement data. This makes its accuracy and stability better than that found for the principal component analysis and linear discriminant analysis methods.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.447-450
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• 2004

This study was conducted to characterize groundwater and river-water fluctuations at a riverbank filtration site in Daesan-myeon adjacent to the Nakdong River, using time series analysis. Water levels from six observation wells from January 2003 to October 2003 were measured. The autocorrelation analysis indicates that the wells are divided into three groups: group 1 represents strong linearity and memory, group 2 intermediate linearity and memory, and group 3 weak linearity and memory. The analysis indicates that groundwater levels in different monitoring wells vary in response to river-water levels, groundwater withdrawal and seasonal rainfall. Cross-correlation was also divided into three groups. Group 1 shows the highest cross-correlation function (0.49 - 0.54) for a lag time of 0 hours, group 2 intermediate cross-correlation function (0.34 - 0.45), and group 3 the lowest cross-correlation function (0.23 - 0.25). Different cross-correlation functions among the 3 groups are interpreted as an effect of tile distance from the river to the pumping wells.

• 한국대기환경학회지
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• 제9권3호
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• pp.183-190
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• 1993

For the efficient control of photochemical smog materials, the researches on the change patterns of photochemical smog precursors are indispensable. In this study, a time-series analysis was performed for the auto-monitoring data of Kwanghwamun and Jamsil stations in 1990, and the change patterns of photochemical smog materials were studied. Especially, auto-correlation coefficients were analyzed to investigate the cyclic characteristics of pollutants in question and cross-correlation coefficients to investigate the correlations between pollutants adjusted for time lag and between $O_3$ and meteorological factors. Results of researches are as follows: First, in the case of NO and $NO_2$ intimately related to human activities, 12-hour cycle was prevalent. But $O_3$ showed 24-hour cycle. Second, NO showed a relatively high correlation with $O_3$ and usually developed into $O_3$ 5 to 7 hours later. Third, temperature, insolation intensity, and wind speed showed a positive correlation with $O_3$ while relative humidity a negative correlation.

• 대한수의학회지
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• 제44권2호
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• pp.185-193
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• 2004

The effects of membrane lipid peroxidation and retinyl palmitate on rat liver microsomal functions were investigated in vitro. Rat liver homogenates exposed to oxygen tension for 0, 3, 6, 9 or12 hours and lipid peroxidation levels were evaluated by the measurements of fluorescence intensity, malondialdehyde (MDA) and retinyl palmitate. The fluorescence intensity of homogenates and microsomes were elevated and retinyl palmitate concentrations were decreased. But the concentration of MDA was not affected to exposure time. Therefore, fluorescence intensity and retinyl palmitate concentration were used to analyze the correlation between lipid peroxidation and microsomal functions. To investigate the liver microsomal functions, the microsome was isolated from rat liver homogenates exposed to oxygen. The concentration of cytochrome P450 and the activity of NADPH-cytochrome P450 reductase in liver microsomes were gradually decreased with increasing the exposure time. The correlation between fluorescence intensity of microsomes showed a very high inverse correlation of -0.97 and -0.93, respectively. The decrease of cytochrome P450 concentration was due to the regeneration of cytochrome P450 to cytochrome P420. Also, the activities of cytochrome P450-dependent aminopyrine demethylase and benzpyrene hydroxylase of liver microsomes were gradually decreased with increasing the exposure time. The correlation with fluorescence intensity of microsome showed a high inverse correlation of -0.97 and -0.91, respectively. The retinyl palmitate concentrations of rat liver homogenates were decreased with increasing the exposure time. The decrease of retinyl palmitate concentration was followed by a low concentration of cytochrome P450 and activity of NADPH-cytochrome P450 reductase. The correlation indicated high direct correlation of 0.92 and 0.93, respectively. The decrease of retinyl palmitate concentration was also accompanied by the reduction of aminopyrine demethylase and benzpyrene hydroxylase activities. The correlation was analyzed a high direct correlation of 0.90 and 0.85, respectively. In conclusion, these studies have shown that the membrane lipid peroxidation of rat liver microsome proportionally decreased microsomal enzyme activities in vitro experiments.

• 한국광학회지
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• 제19권1호
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• pp.1-8
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• 2008

샥-하트만(Shack-Hartmann) 파면 측정 센서는 여러 분야에서 다양하게 사용되고 있다. 특히 적응광학은 주요 응용분야 중 하나이다. 적응광학 시스템은 실시간으로 빠르게 동작되어야 하므로 고속 파면 측정이 필수적이다. 고속 파면 측정에서는 카메라의 노출시간이 매우 작기 때문에 파면 측정시에 광자 잡음(photon noise)와 판독 잡음(readout noise)등의 잡음의 영향을 크게 받는다. 따라서 잡음에 둔감한 고속 중심점 탐색 알고리즘이 요구된다. 본 논문에서는 잡음에 둔감한 고속 중심점 탐색 알고리즘으로 다중 해상도 상관관계법이 제안되었다. 이 방법은 고속 푸리에 변환(fast Fourier transform)을 이용한 상관관계법과 비교하여 다중 해상도 이미지를 이용함으로써 계산시간을 향상시켰다. 본 논문에서는 무게중심법(center of mass method)과 상관관계법(correlation method)과 다중해상도 상관관계법(multi-resolution correlation method)의 계산시간과 측정 정확도를 비교하기 위해 전산모사 방법이 사용되었다. 제안된 방법의 정확도는 기존의 상관관계법과 유사한 것을 확인하였다.

• Journal of Information Technology Applications and Management
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• 제24권1호
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• pp.157-167
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• 2017

This paper proposes a simple sound source localization (SSL) method based on signal energies comparison and partial cross correlation for TDOA computation. Many sound source localization methods include multiple TDOA computations in order to eliminate front-back confusion. Multiple TDOA computations however increase the methods' computation times which need to be as minimal as possible for real-time applications. Our aim in this paper is to achieve the same results of localization using fewer computations. Using three microphones, we first compare signal energies to predict which quadrant the sound source is in, and then we use partial cross correlation to estimate the TDOA value before computing the azimuth value. Also, we apply a threshold value to reinforce our prediction method. Our experimental results show that the proposed method has less computation time; spending approximately 30% less time than previous three microphone methods.

• 전기학회논문지
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• 제64권3호
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• pp.498-504
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• 2015

This paper proposed an Spread Spectrum Time Domain Reflectometry (SSTDR) using time-frequency correlation analysis in order to have more accurate fault determination and location detection than classical SSTDR despite increased signal attenuation due to the long distance to cable fault location. The proposed method was validated through comparison with classical SSTDR methods in open- and short-circuit fault detection experiments of low-voltage power cables. The experimental results showed that the proposed method can detect correlation coefficients at fault locations accurately despite reflected signal attenuation so that cable faults can be detected more accurately and clearly in comparison to existing methods.

• 한국정보처리학회논문지
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• 제6권2호
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• pp.459-466
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• 1999

I broadband ISDN every packet will show different result if it would be processed according to its usage by the server. That is, normal data won't show big differences if they would be processed at normal speed. But it will improve the quality of service to process some kinds of data - for example real time video or voice type data or some data for a bid to by something through the internet - more fast than the normal type data. solution for this problem was suggested - priority packets. But the analyses of them are under way. Son in this paper a switching system for an output queuing model in a single server was assumed and some packets were given priorities and analysed. And correlation, simulating real life situation, was given too. These packets were analysed through three cases, first packets having no correlation, second packets having only correlation and finally packets having priority three cases, first packets having no correlation, second packets having only correlation and finally packets having priority and correlation. The result showed that correlation doesn't affect the mean delay time and the high priority packets have improved mean delay time regardless of the arrival rate. Those packets were assumed to be fixed-sized like ATM fixed-sized cell and the contention strategy was assumed to be short bus contention method for the output queue, and the mean delay length and the maximum 버퍼 length not to lose any packets were analysed.