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Performance of MC-CDM Systems With MMSEC Over Rayleigh Fading Channels
Yusung Lee,Namshik Kim,Hyuncheol Park IEEE 2010 IEEE Transactions on Vehicular Technology VT Vol.59 No.6
<P>In this paper, we investigate the performance of multicarrier code-division multiplexing (MC-CDM) systems with minimum mean square error combining (MMSEC) over a Rayleigh fading channel. An approximated expression on the symbol error rate (SER) for MMSEC is derived. The approximated expression provides an accurate approximation of the true SER, particularly for systems with higher modulation and a small spreading factor. Through the derived error performances, we also calculate the achievable diversity order. MC-CDM systems with MMSEC achieve the same asymptotical diversity order of 1, regardless of the spreading factor. Within practical signal-to-noise ratio (SNR) ranges, the effective diversity order is further increased as a larger spreading factor is used. The derived analytical expressions are verified by numerical and simulation results.</P>
BER Performance of Downlink MC-CDMA with ORC in Nakagami-<i>m</i> Fading Channel
LEE, Yusung,KIM, Namshik,PARK, Hyuncheol The Institute of Electronics, Information and Comm 2009 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.92 No.4
<P>In this letter, we derive an exact bit error rate (BER) expression for downlink multi-carrier code division multiple access (MC-CDMA) systems with orthogonal restoring combining (ORC) in Nakagami-<I>m</I> fading channel. A simple approximated expression is also provided. For uncoded and coded MC-CDMA systems, the BER expressions are calculated based on the moment generating function (MGF) of the combined fading random variable. The derived analytic expressions are verified by simulation results.</P>
Kim, Yusung,Noh, Seungtak,Cho, Gu Young,Park, Taehyun,Lee, Yoon Ho,Yu, Wonjong,Lee, Yeageun,Tanveer, Waqas Hassan,Cha, Suk Won Korean Society for Precision Engineering 2016 International Journal of Precision Engineering and Vol.17 No.8
Thin film solid oxide fuel cells with nickel oxide - gadolinia doped ceria anodes deposited by sputtering were operated at <TEX>$500^{\circ}C$</TEX>. The fuel cells each have 750 nm - yttria-stabilized zirconia electrolytes and 200 nm - platinum cathodes. The thicknesses of the anodes are 240 nm, 320 nm, and 400 nm. The cell with the 320-nm-thick anode showed the highest maximum power density among all cells. Through electrochemical impedance spectroscopy, the anodic activation resistance and the ohmic resistance were calculated. The anodic activation loss decreased with an increase in the anode thickness. Therefore, the cell with the 400-nm-thick anode showed the lowest activation polarization resistance. Additionally, the ohmic resistance, the sum of various electronic/ionic resistances, was lowest when using the 320-nm-thick anode. The electronic resistance and the ionic resistance of the anode were found to exist in a trade-off relationship owing to the current-collecting method of the anode.
An efficient CP compensation for SC-FDE with insufficient CP symbols
Hankil Lee,Yusung Lee,Hyuncheol Park IEEE 2010 IEEE communications letters Vol.14 No.6
<P>In this letter, we propose a method to mitigate interferences for single carrier frequency domain equalization (SC-FDE) with insufficient cyclic prefix (CP) symbols. The resultant channel matrices are not circulant due to some missing symbols. Unlike OFDM, however, the reconstruction of missing symbols using the estimated symbols is not effective. We propose that these missing symbols may be filled with the symbols in the following received block when the channel is static over the consecutive blocks. Since this method does not require estimation of symbols, the precision of detection can be enhanced. The improvement in the performance of this method is still limited since interferences are not completely removed. An iterative interference cancellation method is used to remove the residual interferences. The performance of proposed method is verified by simulations.</P>
Jin, Yusung,Lee, Dongkyu,Lee, Sangkyu,Moon, Wonkyu,Jeon, Sangmin American Chemical Society 2011 ANALYTICAL CHEMISTRY - Vol.83 No.18
<P>We investigated the adsorption and desorption of CO<SUB>2</SUB> on activated carbon using piezoelectric microcantilevers. After coating the free end of a cantilever with activated carbon, variations in the resonance frequency of the cantilever were measured as a function of CO<SUB>2</SUB> pressure, which is related to mass changes due to the adsorption or desorption of CO<SUB>2</SUB>. The pressure-dependent viscous damping effects were compensated in the calculation of the CO<SUB>2</SUB> adsorption capacity of the activated carbon by comparing the frequency differences between the coated and uncoated cantilevers. The mass sensitivity of the piezoelectric cantilever was found to be better than 1 pg. The fractional coverage of CO<SUB>2</SUB> agreed with a Langmuir adsorption isotherm, indicating that a submonolayer of adsorbed CO<SUB>2</SUB> occurred on the surface of the activated carbon under the experimental conditions. The heat of adsorption was determined using the Clausius–Clapeyron relation and the fractional coverage of CO<SUB>2</SUB> at various temperatures and pressures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2011/ancham.2011.83.issue-18/ac201786n/production/images/medium/ac-2011-01786n_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ac201786n'>ACS Electronic Supporting Info</A></P>