• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.11
• /
• pp.1420-1422
• /
• 2016

In order to guarantee the multiuser transmission performance of a chirp spread spectrum system, the cross-correlation coefficient (CCC) among multiple users should be carefully considered. In this paper, we propose a chirp rate allocation scheme for reducing the multiple access interference based on the cross-correlation coefficient. The simulation results show that the proposed scheme can improve the multiple access interference performance.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.11
• /
• pp.1417-1419
• /
• 2016

In order to improve the transmission performance of a chirp signal-based chirp spread spectrum system, the cross-correlation coefficient (CCC) should be carefully considered. In this paper, we derive the CCC for analyzing the transmission performance and propose the optimal chirp rate based on the analysis. The simulation results verify the mathematical derivations and show that the considered scheme can improve the performance by considering the CCC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.3
• /
• pp.403-409
• /
• 2000

In this paper, we measured and analyzed cross polarization discrimination(XPD), signal correlation coefficient($\rho$) and received signal level decrease, for the application of polarization diversity scheme in the up-link of microcell environments. We experimented in a dense building area, a dense residence area, a market area, a school area and etc at 1.9 GHz. Cross polarization discrimination (XPD) is about 6~11 dB, signal correlation coefficient($\rho$) is below 0.7 and received signal level decrease is smaller than 3 dB. The results of comparing polarization diversity with space diversity show that polarization diversity gain is about 2~5 dB higher in the various area. As a results, polarization diversity scheme is more effective than space diversity scheme in microcell environments.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.1102-1107
• /
• 2005

The analysis of the thermal boundary resistance is very important in the both cases of microscale and macroscale systems because it plays a role of thermal barrier against a heat flow. Especially, since fairly large heat energy is generated in microscale or nanoscale systems with electronic chips, the thermal boundary resistance is a key factor to guarantee the performance of those devices. In this study, the transfer of the oscillator's motion information with 2 degrees of freedom is investigated for clarifying the mechanism of a thermal boundary resistance. We found that the transfer of the oscillator's motion information is defined as a cross-correlation coefficient and the magnitude of it determines the temperature jump over a solid interface. That is, the temperature jump over an interface increases as the magnitude of a cross-correlation coefficient decreases and vice versa.

• Journal of the Korean earth science society
• /
• v.34 no.1
• /
• pp.1-12
• /
• 2013

To effectively remove chaff echoes, which are often misidentified as precipitation echoes on weather radars, this study examines the relationship between the radar reflectivity and each of dual polarimetric parameters. The dual polarimetric parameters are collected only for the echo areas identified as chaff echoes on the NIMR X-band dual polarization radar. Overall, the polarimetric parameters (i.e., reflectivity, differential reflectivity, cross correlation coefficient, standard deviation of differential reflectivity and specific differential phase) for chaff echoes have a wider range of values than those for precipitation echoes and the chaff filaments tend to be horizontally oriented to radar beams. There appears to be a considerable overlap in the cross correlation coefficient range of chaff and precipitation echoes since some precipitation echoes have cross correlation coefficient lower than 0.8. Therefore, although the cross correlation coefficient is known to be a good variable in identifying and separating chaff echoes from precipitation echoes, it is suggested that additional care should be taken when using the cross correlation coefficient solely in removing chaff echoes.

• Molecules and Cells
• /
• v.26 no.1
• /
• pp.87-92
• /
• 2008

We employed dual color Fluorescence Cross Correlation Spectroscopy (FCCS) to measure the interaction between PKA regulatory (RII) and catalytic subunits (CAT) in living cells. Elevation of intracellular cAMP with forskolin decreased the cross-correlation amplitude between RFP-fused RII (RII -mRFP) and GFP-fused CAT (CAT-EGFP) by 50%, indicating that cAMP elevation leads to dissociation of RII-CAT complexes. Moreover, diffusion coefficient analysis showed that the diffusion rate of CAT-EGFP was significantly increased, suggesting that the decreased RII-CAT association caused by cAMP generated free CAT subunits. Our study demonstrates that in vivo FCCS measurements and their quantitative analysis permit one not only to directly quantify protein-protein interactions but also to estimate changes in the intracellular cAMP concentration.

• Journal of the Korean Society of Tobacco Science
• /
• v.3 no.1
• /
• pp.41-48
• /
• 1981

Dihaploid lines were derived from the anthers of the F, of single cross, "Va 115" x"SC 72" (Nicotiana tabacum L.). The path-analysis, correlation coefficient, and variation of characteristics among dihaploid families were evaluated. Dihaploid lines displayed much greater variation than their parents. The genetic correlation coefficient between yield and total alkaloids of dihaploids was significantly lower than that of conventional varieties and lines. In path-analysis which relates yield components to yield, number of leaves harvested and leaf width had a direct effect on yield. a direct effect on yield.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.2
• /
• pp.122-129
• /
• 2014

Identification of the whipping response out of the combined wave-vibration response of a flexible sea going vessel is one of the most interesting research topic from ship designer's point of view. In order to achieve this goal, a novel methodology based on the wavelet cross-correlation technique was proposed in this paper. The cross-correlation of the wavelet power spectrum averaged across the frequency axis was introduced to check the similarity between the combined wave-vibration response and impulse response. The calculated cross-correlation of the wavelet power spectrum was normalized by the auto-correlation of the each spectrum with zero time lag, eventually providing the cross-correlation coefficient that stays between 0 and 1, precisely indicating the existence of the impulse response buried in the combined wave-vibration response. Additionally, the weight function was introduced while calculating the cross-correlation of the two spectrums in order to filter out the signal of lower frequency so that the accuracy of the similarity check becomes as high as possible. The validity of the proposed methodology was checked through the application to the artificially generated ideal combined wave-vibration signal, together with the more realistic signal obtained by running 3D hydroelasticity program WISH-Flex. The correspondence of the identified whipping instances between the results, one from the proposed method and the other from the calculated slamming modal force, was excellent.

• Smart Structures and Systems
• /
• v.11 no.4
• /
• pp.349-364
• /
• 2013

Recently, researchers in the field of structural health monitoring (SHM) have been rigorously striving to replace the conventional NDE techniques with the smart material based SHM techniques, employing smart materials such as piezoelectric materials. For instance, the electromechanical impedance (EMI) technique employing piezo-impedance (lead zirconate titanate, PZT) transducer is known for its sensitivity in detecting local damage. For practical applications, various external factors such as fluctuations of temperature and loading, affecting the effectiveness of the EMI technique ought to be understood and compensated. This paper aims at investigating the damage monitoring capability of EMI technique in the presence of axial stress with fixed boundary condition. A compensation technique using effective frequency shift (EFS) by cross-correlation analysis was incorporated to compensate the effect of loading and boundary stiffening. Experimental tests were conducted by inducing damages on lab-sized aluminium beams in the presence of tensile and compressive forces. Two types of damages, crack propagation and bolts loosening were simulated. With EFS for compensation, both cross-correlation coefficient (CC) index and reduction in peak frequency were found to be efficient in characterizing damages in the presence of varying axial loading.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.3 no.4
• /
• pp.23-27
• /
• 2010

This paper performs emotion classification test to find out the best parameter of electroencyphalogram(EEG) signal. Linear predictor coefficients, band cross-correlation coefficients of fast Fourier transform(FFT) and autoregressive model spectra are used as the parameters of 10-channel EEG signal. A multi-layer neural network is used as the pattern classifier. Four emotions for relaxation, joy, sadness, irritation are induced by four university students of an acting circle. Electrode positions are Fp1, Fp2, F3, F4, T3, T4, P3, P4, O1, O2. As a result, the Linear predictor coefficients showed the best performance.