• ETRI Journal
• /
• v.40 no.5
• /
• pp.582-591
• /
• 2018

In this paper, we present a performance analysis of large-scale multi-input multi-output (MIMO) systems for wireless backhaul networks. We focus on fully connected N nodes in a wireless meshed and multi-hop network topology. We also consider a large number of antennas at both the receiver and transmitter. We investigate the transmission schemes to support fully connected N nodes for half-duplex and full-duplex transmission, analyze the achievable ergodic sum rate among N nodes, and propose a closed-form expression of the achievable ergodic sum rate for each scheme. Furthermore, we present numerical evaluation results and compare the resuts with closed-form expressions.

• Proceedings of the IEEK Conference
• /
• 2007.07a
• /
• pp.83-84
• /
• 2007

Multiple-input multiple-output (MIMO) systems can achieve the increasing of performances by using an adaptive power allocation. The related previous work limited the transmit antenna number because orthogonal space-time block codes (OSTBCs) yield full transmit rate only for two transmit antennas. We extend a robust system under imperfect channel estimation for four transmission antennas with maintaining a full transmission rate.

• Journal of the Korean Mathematical Society
• /
• v.58 no.1
• /
• pp.45-67
• /
• 2021

In this paper, a mathematical dynamical system involving both deterministic (with or without delay) and stochastic "SIR" epidemic model with nonlinear incidence rate in a continuous reactor is considered. A profound qualitative analysis is given. It is proved that, for both deterministic models, if ��d > 1, then the endemic equilibrium is globally asymptotically stable. However, if ��d ≤ 1, then the disease-free equilibrium is globally asymptotically stable. Concerning the stochastic model, the Feller's test combined with the canonical probability method were used in order to conclude on the long-time dynamics of the stochastic model. The results improve and extend the results obtained for the deterministic model in its both forms. It is proved that if ��s > 1, the disease is stochastically permanent with full probability. However, if ��s ≤ 1, then the disease dies out with full probability. Finally, some numerical tests are done in order to validate the obtained results.

• International Journal of Korean Welding Society
• /
• v.1 no.1
• /
• pp.44-50
• /
• 2001

A genetic algorithm was applied to the arc welding process as to determine the near-optimal settings of welding process parameters that produce the good weld quality. This method searches for optimal settings of welding parameters through the systematic experiments without the need for a model between the input and output variables. It has an advantage of being capable to find the optimal conditions with a fewer number of experiments rather than conventional full factorial designs. A genetic algorithm was applied to the optimization of the weld bead geometry. In the optimization problem, the input variables were wire feed rate, welding voltage, and welding speed. The output variables were the bead height bead width, and penetration. The number of levels for each input variable is 16, 16, and 8, respectively. Therefore, according to the conventional full factorial design, in order to find the optimal welding conditions,2048 experiments must be performed. The genetic algorithm, however, found the near optimal welding conditions in less than 40 experiments.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.21 no.1
• /
• pp.35-41
• /
• 1988

In order to set up a predictive model for effective spat collection of sea mussel Mytilus edulis , the survival rate and time required at each developmental stage of drifting larvae were surveyed during the period from March 14 to July 20 in 1987 at the Naesan Ri, Jinhae Bay, the southern part of Korea. The advent of D - shape larvae ca. $120\times90um$ um long had three peaks in that area: April 15, May 13 and June 7. Umbo shape larvae ca.$188\times162{\mu}m$ and full grown larvae ca. $289\times280{\mu}m$ long also showed three peaks: April 27. May 24 and June 20 for the former, and May 10, June 5 and June 30 for the latter. Eleven to thirteen days were required for D - shape larvae to develop to umbo - shape larvae. The instantaneous death rate was 0.1300 and the daily survival rate 0.8781 at this intermorphological stage. The turnover time of umbo to full grown larvae varied from ten to thirteen days with a instantaneous death rate of 0.1520, daily survival rate of 0.8590, and mean survival rate of $16.89\%$. Twenty - three to twenty - five days were required for each group of the D - shape larvae to reach a full grown stage, and their mean survival rate was $3.55\%$ during this developmental period.

• Journal of Korea Foresty Energy
• /
• v.22 no.3
• /
• pp.20-28
• /
• 2003

This study was subjected to compare seasonal changes of survival rate, relative growth rate, and chlorophyll contents of major oak tree species including Quercus acctissima, Quercus mongolica, Quercus serrata, Quercus varibilis seedlings grown in Quercus acctissima forest under different light intensities. Three light intensities were 81% of sunlight, 34% of sunlight and 21% of sunlight. In each treatment, 100 tree seedlings were planted and survival rate, growth rate, and chlorophyll contents were measured. The highest survival rate was Quercus acctissima in 73% seedlings compared with those subjected to the other tree seedlings in 45~66%. Lowest survival rate was Quercus vnriabilis seedlings in 41%. Oaks tree species of the height, the root collar diameters of the relative growth were better in the seedlings grown in 81% light intensities of full sun. But growth rates decreased rapidly in the shade treatment of 21% light intensities of full sun. Lowest chlorophyll contents(chlorophyll a, b and total) were shown at 21% light intensities of full sun, lowest light intensity treatment in this study This result is thought growth and chlorophyll contents associated with light intensity Also, Physiological characteristics has to be investigated in near future because photosynthesis and chlorophyll contents were strongly related to tree growth with long periods.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08b
• /
• pp.1089-1092
• /
• 2007

New display technologies including LCD and plasma panels and Digital Light Projection (DLP) systems all offer large screens and impressive picture quality. However, flat-panel displays require a sophisticated picture processing to let these panels perform at their optimum levels. This paper explains why motion compensating techniques combined with frame rate conversion and quasi-impulse driving reduces motion blur and film judder for flat panel displays and presents the IC and its system application using this technique.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.1
• /
• pp.139-146
• /
• 2017

The ISDB-T(Integrated Service Digital Broadcasting Terrestrial) can be used in the multipath and impulsive noise, also it provide good performance over mobile reception environment since it use the OFDM(Orthogonal Frequency Division Multiplexing) based transmission technology and time interleaving technology. One segment and full segment are divided according to the number of the assigned segment. And one-segment broadcasting receiver can design and implement without high levels of technology than the full-segment broadcasting receiver using 64QAM(64 Quadrature Amplitude Modulation) since it uses QPSK(Quadrature Phase Shift Keying) modulation/demodulation. However, it has a constraint in the display size and resolution due to data-rate limits. In this paper, we design and implementation of full-segment ISDB-T receiver module which support HD resolution for set-top box, digital TV, navigation. In experimental results, the implemented full-segment ISDB-T receiver module was satisfactory for all of the desired functions.

• Journal of the Korean Electrochemical Society
• /
• v.5 no.1
• /
• pp.13-16
• /
• 2002

The type of graphite(Gr)/ppy, fullerene$(full^-)$ electrode, ppy one modified with $(full^-)$, was prepared with the cell type of Gr/5mM ppy, 1mM $(full^-)$, 0.1M $TBABF_4$, CH3CN/Pt. The values of the ionic formation rate of the it at electrode materials such as Pt/ppy, Pt, Gr and Au were $93.6,\;7.0\times10^2,\;42.6\;and\;1.3\times10^2cms^{-1}$ respectively. The admittance values of the Grippy electrode and the modified Grippy, $(full^-)$ one were five times enhanced $1.7\times10^{-3}S\;to\;8.3\times10^{-3}\;S$ and capacitance values of electrical double layer of them were 174 times increased $2.4\times10^{-6}\;F\;to\;4.2\times10^{-5}\;F$ respectively.

• Journal of the Korean Electrochemical Society
• /
• v.7 no.1
• /
• pp.16-20
• /
• 2004

To electropolymerize Polypyrrole(ppy) film modified with fullerene $ions(full^-)$ the cell, Au/5 mM pyrrole, 1mM fullerene, 0.1M $TBABF_4,\;CH_2Cl_2/Pt$, was employed to Prepare the wafer-like type of $electrode/ppy(full^-)ppy(full^-){\ldots}$ electrodes. They were applied to deposit alkali metal ions with the cell of Au(quartz crystal analyzer; QCA)/ppy$(full^-)$, 0.01M metal ion(aq.)/Pt. The depositing rate constant of each ion for $Li^+,\;Na^+,\;K^+,\;Rb^+\;and\;Cs^+$, determined from the first order equation was $1.60\times10^{-8},\;3.13\times10^{-11},\;1.38\times10^{-9},\;2.71\times10^{-11}\;and\;2.98\times10^{-12}mo1.s^{-1}$ respectively. The calculated stoichiometry of the ions determined by quartz crystal microbalance(QCM) at the electrodes was $Li_7C_{60},\;Na_4C_{60},\;K_3C_{60},\;Rb_1C_{60}\;and\;Cs_1C_{60}$ respectively.