• ETRI Journal
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• v.41 no.5
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• pp.574-584
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• 2019

A new Mirai variant found recently was equipped with a dynamic update ability, which increases the level of difficulty for DDoS mitigation. Continuous development of 5G technology and an increasing number of Internet of Things (IoT) devices connected to the network pose serious threats to cyber security. Therefore, researchers have tried to develop better DDoS mitigation systems. However, the majority of the existing models provide centralized solutions either by deploying the system with additional servers at the host site, on the cloud, or at third party locations, which may cause latency. Since Internet service providers (ISP) are links between the internet and users, deploying the defense system within the ISP domain is the panacea for delivering an efficient solution. To cope with the dynamic nature of the new DDoS attacks, we utilized an unsupervised artificial neural network to develop a hierarchical two-layered self-organizing map equipped with a twofold feature selection for DDoS mitigation within the ISP domain.

• Journal of Microbiology and Biotechnology
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• v.29 no.11
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• pp.1841-1851
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• 2019

Garcinol, a well-known medicinal phytochemical, was extracted and isolated from the dried fruit rinds of Garcinia quaesita Pierre. In this study, garcinol has successfully used to reduce silver ions to silver in order to synthesize garcinol-capped silver nanoparticles (G-AgNPs). The formation and the structure of G-AgNPs were confirmed by UV-visible spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The antimicrobial activity of garcinol and G-AgNPs were investigated by well diffusion assays, broth micro-dilution assays and time-kill kinetics studies against five microbial species, including Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Candida albicans (ATCC 10231) and clinically isolated methicillin-resistant Staphylococcus aureus (MRSA). The formation of G-AgNPs is a promising novel approach to enhancing the biological activeness of silver nanoparticles, and to increase the water solubility of garcinol which creates a broad range of therapeutic applications.

• Biomolecules & Therapeutics
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• v.27 no.6
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• pp.540-552
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• 2019

To determine the chemopreventive potential of alyssin and iberin, the in vitro anticancer activities and molecular targets of isothiocyanates (ITCs) were measured and compared to sulforaphane in hepatocellular carcinoma cell HepG2. The SR-FTIR spectra observed a similar pattern vis-a-vis the biomolecular alteration amongst the ITCs-treated cells suggesting a similar mode of action. All of the ITCs in this study cause cancer cell death through both apoptosis and necrosis in concentration dependent manner ($20-80{\mu}M$). We found no interactions of any of the ITCs studied with DNA. Notwithstanding, all of the ITCs studied increased intracellular reactive oxygen species (ROS) and suppressed tubulin polymerization, which led to cell-cycle arrest in the S and $G_2/M$ phase. Alyssin possessed the most potent anticancer ability; possibly due to its ability to increase intracellular ROS rather than tubulin depolymerization. Nevertheless, the structural influence of alkyl chain length on anticancer capabilities of ITCs remains inconclusive. The results of this study indicate an optional, potent ITC (viz., alyssin) because of its underlying mechanisms against hepatic cancer. As a consequence, further selection and development of effective chemotherapeutic ITCs is recommended.

• Natural Product Sciences
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• v.25 no.1
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• pp.11-15
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• 2019

Lauraceae is a family medicinal plant whose tubers possesses antimicrobial, and cytotoxic, such as antiparasitic and anti-inflammatory special effects and has been used for the medicine in the cure of hepatitis and rheumatism. The antimicrobial activities of bioactive compounds including one neolignan; kunstlerone (1) and two alkaloids include isocaryachine (2) and noratherosperminine (3) as well as crude hexane, methanol and dichloromethane extracts were evaluated. Additionally, the effect of compounds 1, 2 and 3 were evaluated on A549, PC-3, A375, HT-29 and WRL-68 cell lines. In conclusion, kunstlerone 1 showed moderate cytotoxicity against various cancer cell lines such as A549, PC-3, A375, HT-29 and WRL-68, respectively with $EC_{50}$ values of 28.02, 26.78, 33.78, 33.65 and $16.46{\mu}g/mL$. The crude methanol extract showed antigrowth activity against S. pyogenes II and B. cereus, with MICs of $256{\mu}g/mL$. The compounds kunstlerone (1), isocaryachine (2) and noratherosperminine (3) showed complete inhibition against P. shigelloides, with MIC ${\leq}60{\mu}g/mL$ compare to ampicillin, as a positive control, which showed antigrowth activity against P. shigelloides at MIC $10{\mu}g/mL$.

• Particle and aerosol research
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• v.15 no.3
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• pp.115-126
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• 2019

In this study, a serial methodology is presented for estimating the effective density of ambient sub-micron aerosol employing lab-made 1 stage low-pressure impactor of Hyun et al. (2015) and SMPS (Scanning Mobility Particle Sizer) together. The effective density from this methodology (Impactor+SMPS) was compared with another methodology (BAM+SMPS) for estimating the effective density employing BAM (Beta-Attenuation Monitor) and SMPS. As a result, the effective density obtained with impactor+SMPS ranged from $0.42g/cm^3$ to $2.36g/cm^3$, while the effective density obtained with BAM+SMPS ranged from $1.01g/cm^3$ to $1.72g/cm^3$. The difference between these results might be caused by the particle loss in the impactor.

• Journal of the Korean Mathematical Society
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• v.56 no.6
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• pp.1529-1560
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• 2019

We are concerned with the following elliptic equations: $$(-{\Delta})^s_pu+V (x){\mid}u{\mid}^{p-2}u={\lambda}g(x,u){\text{ in }}{\mathbb{R}}^N$$, where $(-{\Delta})_p^s$ is the fractional p-Laplacian operator with 0 < s < 1 < p < $+{\infty}$, sp < N, the potential function $V:{\mathbb{R}}^N{\rightarrow}(0,{\infty})$ is a continuous potential function, and $g:{\mathbb{R}}^N{\times}{\mathbb{R}}{\rightarrow}{\mathbb{R}}$ satisfies a $Carath{\acute{e}}odory$ condition. We show the existence of at least one weak solution for the problem above without the Ambrosetti and Rabinowitz condition. Moreover, we give a positive interval of the parameter ${\lambda}$ for which the problem admits at least one nontrivial weak solution when the nonlinearity g has the subcritical growth condition.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.4
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• pp.1941-1960
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• 2019

Unmanned aerial vehicles (UAVs), acting as mobile base stations (BSs), can be deployed in the typical fifth-generation mobile communications (5G) scenarios for the purpose of substantially enhancing the radio coverage. Meanwhile, UAV aided underlay device-to-device (D2D) communication mode can be activated for further improving the capacity of the 5G networks. However, this UAV aided D2D communication system is more vulnerable to eavesdropping attacks, resulting in security risks. In this paper, the D2D receivers work in full-duplex (FD) mode, which improves the security of the network by enabling these legitimate users to receive their useful information and transmit jamming signal to the eavesdropper simultaneously (with the same frequency band). The security communication under the UAV coverage is evaluated, showing that the system's (security) capacity can be substantially improved by taking advantage of the flexible radio coverage of UAVs. Furthermore, the closed-form expressions for the coverage probabilities are derived, showing that the cellular users (CUs)' secure coverage probability in downlink transmission is mainly impacted by the following three factors: its communication area, the relative position with UAV, and its eavesdroppers. In addition, it is observed that the D2D users or DUs' secure coverage probability is relevant to state of the UAV. The system's secure capacity can be substantially improved by adaptively changing the UAV's position as well as coverage.

• Journal of Applied Biological Chemistry
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• v.62 no.3
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• pp.265-273
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• 2019

This study aimed to evaluate the anti-atherosclerotic and anti-hypertensive effects of six different plant extracts using a N(G)-nitro-L-arginine-methyl ester (L-NAME)-induced rat model of hypertension. All extracts were administered orally for six weeks. At the end of the study period blood pressure, blood flow, aortic histopathology, and hepatic endothelial nitric oxide synthase (eNOS) expression were measured. Subsequently, we also measured the levels of intracellular reactive oxygen species, nitric oxide (NO), and anti-inflammatory cytokines in vitro. Based on these screening results, we selected extracts of Cinnamomum cassia (C. cassia) and Salvia miltiorrhiza (S. miltiorrhiza) for further evaluation. C. cassia and S. miltiorrhiza extracts ameliorated hypertension and atherosclerosis in L-NAME-treated rats in a dose-dependent manner. In addition, a mixture of C. cassia and S. miltiorrhiza had an additive effect to reduce blood pressure, increase blood flow, and normalize aortic tissue. This mixture demonstrated anti-oxidative and anti-inflammatory activities in vitro. In conclusion, although further analysis of the therapeutic mechanism is required, the anti-hypertensive and anti-atherosclerotic effects of this mixture are likely mediated by increased eNOS expression, and its anti-oxidative and anti-inflammatory activities.

• Journal of Genetic Medicine
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• v.16 no.1
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• pp.31-38
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• 2019

Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a maternally inherited mitochondrial disorder of which m.3243A>G is the most commonly associated mutation, resulting in an inability to meet the energy requirements of various organs. MELAS poses a diagnostic challenge owing to its multiple organ involvement and great clinical variability due to its heteroplasmic nature. We report three cases from a family who were initially misdiagnosed with myasthenia gravis or undiagnosed. Although there is no optimal consensus treatment approach for patients with MELAS because of the disease's heterogeneity, our 21-year-long therapy regimen of ${\text\tiny{L}}-arginine$, ${\text\tiny{L}}-carnitine$, and coenzyme Q10 supplementation combined with dietary management appeared to provide noticeable protection from the symptoms and complications. Prompt early diagnosis is important, as optimal multidisciplinary management and early intervention may improve outcomes.

• Electronics and Telecommunications Trends
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• v.34 no.3
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• pp.75-85
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• 2019

The bandwidth of wireless communication is expected to grow exponentially due to the expansion of mobile devices and the increase of real-time and realistic multimedia services. Recently, the studies on terahertz band wireless communication have been actively conducted for the next generation communication after 5G wireless communication. The terahertz band, which is the unallocated frequency band, has been applied to the non-contact, non-destructive quality inspection industry such as the terahertz imaging and spectral systems through the development of terahertz generating and detecting components. This article briefly describes recent research trends on terahertz wireless communication technologies and introduces the details of photonics-based terahertz devices and systems that have been focused on the Terahertz Basic Research Section of Electronics and Telecommunication Research Institute.