• Journal of IKEEE
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• v.26 no.4
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• pp.693-704
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• 2022

5G service uses mid-band (n78) than existing mobile communication frequencies, so it is necessary to improve 5G coverage by utilizing low-band frequencies below 2 GHz. To this end, the application of Dynamic Spectrum Sharing technology of LTE and 5G-NR system using most of the low-band frequencies is required. In this paper, signaling overhead factors for DSS application and RF issues for terminal implementation are derived, and signaling overhead ratios from the respective perspectives of 5G-NR and LTE for the 1.8GHz band (50MHz width) that can utilize wide-bandwidth among low-band frequencies are estimated. Also handset RF issues were analyzed. Based on the analysis results, if DSS technology using low band is applied, it is expected that excellent 5G service quality can be provided due to 5G coverage improvement when LTE traffic quickly migrates to 5G-NR.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.4
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• pp.181-188
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• 2006

The purpose of this study is to predict the defibrillation success of a ventricular Fibrillation ECG signal using time-frequency analysis. During CPR, coronary perfusion pressure and electrocardiogram were measured. Parameters extracted from time-frequency domain were served as predictor of resuscitation success. Time frequency distribution(TFD) of ECG signals was estimated from the smoothed pseudo Wigner-Ville distribution(SPWVD). Median frequency, peak frequency, 1/f slope, frequency band ratios$(2{\sim}4Hz,\;4{\sim}6Hz,\;6{\sim}8Hz,\;8{\sim}10Hz,\;10{\sim}12Hz,\;12{\sim}15Hz)$ were extracted from each TFD as function of time. Paired t-test was used to determine the differences in ROSC and non-ROSC groups. In the statistical results, we selected four significant parameters - median frequency, 1/f slope, $2{\sim}4Hz$ band ratio, $8{\sim}10Hz$ band ratio. We made an attempt to predict defibrillation success by combining features extracted from time frequency distribution. Independent t-test was used to determine the differences ROSC and non-ROSC groups. Consequently, we selected four significant parameters-median frequency, 1/f slope, $2{\sim}4Hz$ band ratio, $8{\sim}10Hz$ band ratio. The relationship between coronary perfusion pressure and ECG parameters was analyzed with linear regression analysis. R-square value was 55%. 1/f slope and $8{\sim}10Hz$ band ratio had the significant relationship with coronary perfusion pressure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.712-718
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• 2004

We report 1.6 Tb/s (160${\times}$10 Gb/s) WDM transmission over 2,000 km of single mode fiber using distributed hybrid(distributed Raman amplifier＋Erbium-doped fiber amplifier) optical amplifiers. After transmission over 2,000 km of single mode fiber, average optical signal to noise ratios of C/L-band were 20.5 dB, 21.9 dB, respectively. The minimum Q-factors of each band were 14.65 dB (BER=5.8e-8) in C-band, 13.75 dB (BER=5.0e-7) in L-band without forward error correction. We performed 1.6 Tb/s error-free transmission over 2,000 km of single mode fiber using Reed-Solomon (255, 239) forward error correction code.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.4
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• pp.299-307
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• 2011

The offshore plants such as FPSO are subjected to combination loading of environmental conditions (swell, wave, wind and current). Therefore the fatigue damage is occurred in the operation time because the units encounter the environmental phenomena and the structural configurations are complicated. This paper is a research for frequency domain fatigue analysis of wide-band random loading focused on accuracy of fatigue damage estimation regarding the proposed methods. We selected ideal bi-modal spectrum. And comparison between time-domain fatigue analysis and frequency-domain fatigue analyses are conducted through the fatigue damage ratio. Fatigue damage ratios according to Vanmarcke's bandwidth parameter are founded for wide-band. Considering safety, we recommend that Jiao-Moan and Tovo-Benasciutti methods are optimal way at the fatigue design for wide-band response. But, it is important that these methods based on frequency-domain unstably change the accuracy according to the material parameter of S-N curve. This study will be background and guidance for the new frequency-domain fatigue analysis development in the future.

• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.388-395
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• 2009

To investigate the flexural behavior of RC beams strengthened with glass fiber sheets, 1 control beam and 8 strengthened beams (4 NU-beams without U-shaped band and 4 U-beams with U-shaped band) are tested. The variables of experiment are composed of the number of glass fiber sheets and the existence of U-shaped band, etc. The maximum load was increased by 48% and 34%, and the flexural rigidity by 920% and 880% for NU-beam and U-beam, respectively, compared with those of the control beam. The ductility ratios were 1.43$\sim$2.60 for NU-beam and U-beam. The experimental results showed that the strengthening system with U-shaped band controls the premature debonding and provides a more ductile failure mode than the strengthening system without U-shaped band. It can be found from the load-deflection curves that as the number of fiber sheets is increased, the maximum strength and the flexural rigidity is increased. The experimental results are compared with the analytical results of nonlinear flexural behaviors for strengthened RC beam. The experimental and analytical results were well agreed.

• Journal of ILASS-Korea
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• v.6 no.3
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• pp.1-7
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• 2001

In this study, quantitative measurement of nitric oxide concentration distributions visualization were investigated in the laminar $CH_4/O_2N_2$ nixed flame by Planar laser-induced fluorescence(PLIF). The NO A-X (0,0) vibrational band around 226nm was excited using a XeCl excimer-pumped dye laser. Selecting an appropriate NO transition minimizes interference from Rayleigh scattering and $O_2$ fluorescence. The measurements were taken in $CH_4/O_2N_2$ premixed flame with equivalence ratios varying from $1.0{\sim}1.6$, and a fixed flow rate of 3slpm. NO was found to produce primarily between an inner premixed and an outer nonpremixed flame front, and total NO concentration is raised when equivalence ratios increase. These results suggest that prompt NO is likely to contribute to MO formation in $CH_4/O_2N_2$ premixed flame. Furthermore, this trend was well matched with previous works.

• Journal of ILASS-Korea
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• v.7 no.4
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• pp.42-49
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• 2002

In this study, quantitative measurement of nitric oxide concentration distributions were investigated in the laminar CH4/O2/N2 premixed flame by laser-induced fluorescence (LIF). The NO A-X (0,0) vibrational band around 226nm was excited using a XeCl excimer-pumped dye laser. Selecting an appropriate NO transition minimizes interference from Rayleigh scattering and O2 fluorescence. The measurements were taken in CH4/O2/N2 premixed flame with equivalence ratios varying from $1.0{\sim}1.6$, and a fixed flowrate of 5slpm. NO was found to produce primarily between an inner premixed and an outer nonpremixed flame front, and total NO concentration is raised when equivalence ratios increase. These results suggest that prompt NO is likely to contribute to NO formation in CH4/O2/N2 premixed flame. Furthermore, this trend was well matched with previous works.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.156-161
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• 2000

In this study, quantitative nitric oxide concentration distributions are investigated in the post-flame zone of laminar premixed $CH_4/O_2/N_2$, flames by laser-induced fluorescence (LIF). The measurements are taken in flames for different equivalence ratios varying from $0.8{\sim}1.4$, and flow rate is fixed as 5slpm. The NO A-X (0,0) vibrational band around 226 nm is excited using a XeCl excimer-pumped dye laser. Selecting an appropriate NO transition minimizes interferences from Rayleigh scattering and $O_2$ fluorescence. NO concentration is rised when equivalence ratios increase at different vertical distances form nozzle tip. In any case, the maximum NO concentration reaches the maximum in reaction zone.

• Korean Journal of Remote Sensing
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• v.23 no.1
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• pp.1-5
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• 2007

Relatively simplified method for determination of surface reflectance has been used by using the ratio between SWIR and VIS band reflectance over land surface. The surface reflectance ratios (SWIR/VIS) were estimated over land in Korea from Terra Moderate Resolution Imaging Spectre-radiometer (MODIS) L1 data. The ratios by using the minimum reflectance technique were lower than those by MODIS operational aerosol retrieval algorithm. Although the comparison between MODIS and sunphotometer Aerosol Optical Thickness (AOT) has a good correlation coefficient (R=0.84), slightly overestimated MODIS AOTs were shown with a slope of linear regression line of 0.89. The comparison between the ratio and AOT dearly exhibit that the error of MODIS AOT could be originated from the underestimated surface reflectances by MODIS operational algorithm.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3395-3399
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• 2011

Copper oxide thin films were synthesized by reactive radio frequency magnetron sputtering at different oxygen gas ratios. The chemical and physical properties of the thin films were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). XPS results revealed that the dominant oxidation states of Cu were $Cu^0$ and $Cu^+$ at 0% oxygen ratio. When the oxygen ratios increased above 5%, Cu was oxidized as CuO as detected by X-ray induced Auger electron spectroscopy and the $Cu(OH)_2$ phase was confirmed independent of the oxygen ratio. The valence band maxima were $1.19{\pm}0.09$ eV and an increase in the density of states was confirmed after formation of CuO. The thickness and roughness of copper oxide thin films decreased with increasing oxygen ratio. The crystallinity of the copper oxide films changed from cubic Cu through cubic $Cu_2O$ to monoclinic CuO with mean crystallite sizes of 8.8 nm (Cu) and 16.9 nm (CuO) at the 10% oxygen ratio level.