• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.6
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• pp.479-485
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• 2013

Recently, interest for wireless communication technology with improved security and low eavesdropping probability is increasing rapidly recognizing that information security is an important. Chaos signal can be used encode information efficiently due to irregular phenomena. Chaotic signal is very sensitive to the initial condition. Chaos signal is difficult to detect the signal if you do not know the initial conditions. Also, chaotic signal has robustness to multipath interference. In this paper, we evaluate the performance of correlation delay shift keying (CDSK) modulation with different chaotic map such as Tent map, Logistic map, Henon map, and Bernoulli shift map. Also, we analyze the BER performance depending on the selection of spreading factor (SF) in CDSK. Through the theoretical analyses and simulations, it is confirmed that Henon map has better BER performance than the other three chaotic maps when spreading factor is 70.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.577-583
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• 2014

Three major classes of retroviral restriction factors (APOBEC3G, Tetherin, and TRIM5${\alpha}$) have been identified in mammals. Restriction factors are cellular proteins that are able to limit viral replication by targeting specific steps of the viral life cycle. To evaluate which restriction factor is the most effective to inhibit the replication of porcine endogenous retroviruses (PERVs), the antiviral activity of each restriction factor was compared. In pseudotype assay, the antiviral activity of human tetherin against PERV pseudotype was slightly weaker than that of human APOBEC3G (hA3G). A combination of tetherin and hA3G was more potent than each individual restriction factor. We questioned whether a combination of tetherin and hA3G could also inhibit the spreading replication of PERV. In agreement with the pseudotype assay, two restriction factors inhibit infectious PERV replication in a spreading infection. In this study, hA3G could strongly inhibit the replication of PERV, but tetherin modestly restricted it. Based on these results, we concluded that a combination of tetherin and hA3G is the most effective way to restrict PERV. A combination of different restriction factors will encourage the development of a new approach to treat retroviral disease.

• The Journal of the Convergence on Culture Technology
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• v.3 no.4
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• pp.191-198
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• 2017

In this paper, we compare the transmission performance of Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiplexing (OFDM) under long duration multipath channel environments. This paper generates underwater channels through Bellhop based on the underwater environmental data of the west sea. BER performance of CDMA and OFDM are analyzed through various underwater channels based on the channels. Computer simulations result show that CDMA has better performance than OFDM when multipath delay time of underwater channel is shorter than spreading factor (SF). However, OFDM has better BER performance than CDMA as multi-path delay time increases.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.4
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• pp.43-51
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• 2007

Liquefaction-induced lateral spreading continues to be a major cause of damage to deep foundations. Currently there is a huge uncertainty associated with the maximum lateral pressures and forces applied by the liquefied soil to deep foundations. Furthermore, recent centrifuge and is shaking table tests of pile foundations indicate that the permeability of the liquefied sand is an extremely important and poorly understood factor. This article presents experimental results and analysis of one of the centrifuge tests that were conducted at the 150 g-ton RPI centrifuge to investigate the effect of soil permeability in the response of single piles and pile groups to lateral spreading.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.51-57
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• 2001

In order to estimate attenuation characteristics, nonparametric model is used. Evaluation of this model requires suites of average spectral amplitude data as a function of distance without adopting any assumed parametric forms. Values of Quality factor, Q were estimated for individual frequencies by matrix inversion of S wave amplitude spectra for 21 records of 8 small and intermediate earthquakes (2.7$(1/r)^{1/2}$. The best models for 1/Q values were found to be 0.000453+0.001851/f and 0.000451+0.009261/f, respectively. This results can be compared to the conventional functional form of Q=$af^{b}$ and be used to estimate source spectra and site response.

• The KIPS Transactions:PartD
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• v.13D no.3 s.106
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• pp.391-398
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• 2006

This paper verifies deployment algorithms in wireless sensor networks using SPIN, a widely used model checking tool. In this paper, two deployment algorithms, DSSA(Distributed Self Spreading Algorithm) and TBDA(Tree Based Deployment Algorithm), are verified to check their stability against oscillation as well as energy consumption that is an important factor in wireless sensor networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1833-1843
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• 1999

in this paper, we analyze the effects of PN sequence phase on the multiple access interference (MAI) of multi-media multi-rate DS/CDMA system with variable spreading gain (VGS) scheme, and furthermore derive the bit error rate (BER) equation for MAI users with different powers and spreading gains. In the sequel, we verify the influences of deterministic sequences on the bit error rate performance. As the results of the bit error rate of a desired user against interfering users with different spreading gains and different transmit powers, it is shown that the domain factor to determine the MAI component could be different according to the data transmission rate of a desired user. We also show that any kind of PN sequence phase does not yield considerable advantage, unless $E_b/N_o$ is considerably greater than 10dB, since below that value AWGN dominates. However, when the higher $E_b/N_o$, the performance of both MSQCC/CO and CO/MSQCC criterion give the better results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.591-593
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• 2019

LPWA has a small amount of data that can be transmitted at one time, but it can collect a very wide range of information, so it is suitable for gathering information of apartment meter or collecting data intermittently sent from industrial site. However, most of the application studies on LPWA are limited to outdoor, especially LOS environment, so it is difficult to collect information for application to apartment and industrial sites. In this paper, we have measured the communication coverage within the building, which is a NLOS environment, so that LPWA communication can be applied to apartments and industrial sites. For the experiment, LoRa module was created using sx1276, Class A was applied, and the spread factor was changed for each layer. As a result, in case of spreading factor 7 that shows increasing error and losses from the 7 floor, but the in case of spreading factor 12, the data could be seamlessly received even on the 9th floor without error and losses.

• Culinary science and hospitality research
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• v.23 no.2
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• pp.35-44
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• 2017

The purpose of the present study was to investigate the impact of experience factors on brand attitude and revisit intention in cakes specialty shop. The result showed that among experience factors in rice cake specialty shop, educational experience factor and aesthetic experience factor had influence on both brand attitude and revisit intention, and entertainment experience factor had only influence on revisit intention. Also, brand attitude had significant influence on revisit intention. It was confirmed that experience activities in marketing of traditional food such as rice cakes are significant marketing activities, and educational experience factor and aesthetic experience factor have high correlated each other. On the other hand, entertainment experience factor is in lack relatively, which is due to the complexity of the traditional food manufacturing, and future improvements about this needs to be required. This study was to identify marketing significance of experience factors in rice cake specialty shop and to verify the necessity and effectiveness for spreading vigorous marketing in a variety of traditional food fields through this opportunity.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.3
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• pp.178-185
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• 2013

Forest fires are expected to increase in severity and frequency under global climate change and thus better understanding of fire dynamics is critical for mitigation and adaptation. Researchers with different background, such as ecologists, physicists, and mathematical biologists, have developed various simulation models to reproduce forest fire spread dynamics. However, these models have limitations in the fire spreading because of the complicated factors such as fuel types, wind, and moisture. In this study, we suggested a simple model considering the wind effect and two different fuel types. The two fuels correspond to susceptible tree and resistant tree with different probabilities of transferring fire. The trees were randomly distributed in simulation space with a density ranging from 0.0 (low) to 1.0 (high). The susceptible tree had higher value of the probability than the resistant tree. Based on the number of burnt trees, we then carried out the sensitivity analysis to quantify how the forest fire patterns are affected by wind and tree density. The statistical analysis showed that the total tree density had greatest effect on the forest fire spreading and wind had the next greatest effect. The density of the susceptible tree was relatively lower factor affecting the forest fire. We believe that our model can be a useful tool to explore forest fire spreading patterns.