• Journal of Communications and Networks
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• v.5 no.1
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• pp.19-24
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• 2003

A new code, LS code, was proposed for the IMT-2000 CDMA system. The code has special properties during a specific time interval: 1) perfect autocorrelation, and 2) perfect crosscorrelation. Perfect autocorrelation means maximum autocorrelation for zero time-offset and zero autocorrelation for all other times during a specific time interval. Moreover, perfect crosscorrelation means that the crosscorrelation has zero value during a certain time, you can remove all the MAI within that time. However, the detailed properties of LS code and its exact generation method have been previously unknown. Therefore, we investigate the LS code in regards to its exact generating method, properties, and performances in this paper.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.221-224
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• 2001

A new code: LS code was proposed for IMT-2000 CDMA system. The code has special properties during a certain time of interval: 1) perfect autocorrelation 2) perfect crosscorrelation. The perfect autocorrelation means that the autocorrelation has nMaximum for zero time-offset and zero for other times during a certain time. Moreover the perfect crosscorrelation means that the crosscorrelation has zero during a time of interest. In the LAS-DMA system, the LS code is only used in the spreading of data bits in contrast to the conventional CDMA system. Therefore the LS code pair setting and allocation order should be dealt with carefully considering the special properties of LS code. This paper is intended as an investigation of the setting LS code pair and the sequential allocation method. Firstly, the optimum LS code pair set is proposed in order to minimize PAPR. Secondly, the sequential allocation method is studied to either minimize PAPR or expand IFW.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.1
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• pp.47-52
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• 2010

For cryptographic systems, nonlinearity is crucial since most linear systems are easily decipherable. C.Bracken, Z.Zhaetc., propose the APN(Almost Perfect Nonlinear) functions with the properties similar to those of the bent functions with perfect nonlinearity. We design two kinds of new code sequence generating algorithms using the above APN functions. And we find that the out of phase ${\tau}\;{\neq}\;0$, autocorrelation functions, $R_{ii}(\tau)$ and the crosscorrelation functions, $R_{ik}(\tau)$ of the binary code sequences generated by two new algorithms over GF(2), have three values of {-1, $-1-2^{n/2}$, $-1+2^{n/2}$}. We also find that the out of phase ${\tau}\;{\neq}\;0$, autocorrelation functions, $R_{p,ii}(\tau)$ and the crosscorrelation functions, $R_{p,ik}(\tau)$ of the nonbinary code sequences generated by the modified algorithms over GF(p), $p\;{\geq}\;3$, have also three values of {$-1+p^{n-1}$, $-1-p^{(n-1)/2}+p^{n-1}$, $-1+p^{(n-1)/2}p^{n-1}$}. We show that these code sequences have the characteristics of the correlation functions similar to those of Gold code sequences.

• Journal of Soil and Groundwater Environment
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• v.15 no.6
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• pp.1-8
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• 2010

The groundwater level distribution and characteristics of responses to rainfall were examined in the Haean basin of Yangu that has a single stream exit to the east. The groundwater levels showed a circular or elliptical distribution converging the center of the basin with different hydraulic gradients in the north and south regions. The waterlevel elevations exhibited a perfect correlation with topographic elevation ($r^2=0.99$) while the depth to water showed a rather weak correlation ($r^2=0.49$). The water table fluctuation (WTF) method yielded recharge ratios of 6.1~12.65% ($S_y=0.02$) and 15.2~28.5% ($S_y=0.05$). The waterlevels of HG3 well, which is much proximal to a stream, were weakly auto-correlated but they were highly sensitive to direct infiltration from the rainfall event. The shorter regulation times of the HG3 represented a quicker dissipation of the input stress (rainfall).

• The Korean Journal of Applied Statistics
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• v.33 no.2
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• pp.185-201
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• 2020

Scenario population projection reflects the high probability of future realization and ease of statistical interpretation. Statistics Korea (2019) also presents the results of 30 combinations, including special scenarios, as official statistics. However, deterministic population projections provide limited information about future uncertainties with several limitations that are not probabilistic. The deterministic population projections are scenario-based estimates and show a perfect autocorrelation of three factors (birth, death, movement) of population variation over time. Therefore, international organizations UN, the Max Planck Population Research Institute (MPIDR) of Germany and the Vienna Population Research Institute (VID) of Austria have suggested stochastic based population estimates. In addition, some National Statistics Offices have also adopted this method to provide information along with the scenario results. This paper calculates the demographics of Korea based on a probabilistic or stochastic basis and then draws the pros and cons and show implications of the scenario (deterministic) population projections.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.3-9
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• 2013

This paper proposes a selective-weighted energy detection (S-WED) and a synchronization algorithm appropriate for it in IR-UWB system. Energy detectors that are practical in terms of implementation are employed widely for noncoherent reception in IR-UWB systems. However, they show low performance due to using the energy samples captured at symbol rate. For this reason, weighted energy detectors are developed to improve the performance of EDs. Hence, for WED, not only synchronization but also the weight coefficients are needed to be obtained prior to data detection. Meanwhile, the optimal weighting coefficients of WEDs are known to be energy values. Therefore, synchronization and the weighting coefficients can be obtained simultaneously. This paper proposes an S-WED and a simple synchronization algorithm for it in which sub-intervals having energies under a certain level are excluded in energy accumulation resulting in a simpler WED with a bit performance increase in low SNR region. The proposed algorithm is verified through simulations using the preamble symbol and channel models defined in the IEEE 802.15.4a.