• Journal of the Korean Mathematical Society
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• v.61 no.4
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• pp.797-836
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• 2024

We consider the following strongly damped wave equation on ℝ³ with memory u_tt - αΔu_t - βΔu + λu - ∫₀^∞ κ'(s)∆u(t - s)ds + f(x, u) + g(x, u_t) = h, where a quite general memory kernel and the nonlinearity f exhibit a critical growth. Existence, uniqueness and continuous dependence results are provided as well as the existence of regular global and exponential attractors of finite fractal dimension.

• Korean Journal of Poultry Science
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• v.46 no.2
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• pp.127-136
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• 2019

Three strains of infectious bronchitis viruses (IBVs), designated VNUA3, VNUA8 and VNUA11, were isolated from diseased/infected chickens in Hanoi, Thainguyen, and Haiphong provinces of Vietnam. These birds had received a live IBV vaccination but still suffered from infectious bronchitis. VNUA3, VNUA8 and VNUA11 harbor cleavage sites (RRTGR, HRRRR, and HRRKR, respectively) within the S protein. A BLASTN search revealed that the S gene of VNUA3, VNUA8, and VNUA11 showed the highest nucleotide identity with those of IBV strains CK/Italy/I2022/13, CK/CH/LHLJ/08-6, and GX-NN120084, respectively. Phylogenetic analyses based on the S gene nucleotide sequences revealed that VNUA3, VNUA8 and VNUA11 clustered with Q1-like, QX-like and TC07-2-like genotypes, respectively, and were closely related to reference IBV strains from China. However, the Vietnam IBVs showed high divergence from vaccine strains 4/91 and Ma5, which are used in the Vietnamese farms from which the isolates were obtained. Taken together, these results indicate that at least three genotypes of IBV are circulating among chickens in North Vietnam. This is the first report of the molecular epidemiology of IBV in Vietnam.

• Journal of Navigation and Port Research
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• v.40 no.5
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• pp.305-310
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• 2016

The sea-port in Northern Vietnam accounts for around one third of the total country's cargo throughput and for many decades has been playing an important role in the logistics system of the country. 11 container terminals currently operate in Northern Vietnam, concentrating in Haiphong city and Quang Ninh province. Despite the increasing demand, the competition among these container terminals has become increasingly more critical. In recent years, massive investments from both government and operators have been made to improve the capability of the local sea-port's logistics infrastructure. This critically needed comprehensive research evaluates the impact of the current logistics infrastructure condition on the competitiveness of terminals and quantitatively compares the competencies of these terminals. In order to meet such requirements, the paper first summarizes the indicators of the logistics infrastructures of the sea ports before developing and testing hypotheses to reveal the correlation between the given factors and the annual throughput of container terminals in the region. Factor analysis will then be applied to score the logistics infrastructure competency of each container terminal. A significant gap between logistics infrastructures among all container terminals was not observed and the competitiveness between container terminals is mostly driven by traditional activities including cargo handling and storage. According to the results, strategic thinking will be needed to contribute to related organizations for better decisions in investment, management, and operation.

• Bulletin of the Korean Mathematical Society
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• v.61 no.1
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• pp.161-193
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• 2024

In this paper, we consider the asymptotic behavior of solutions for the partly dissipative reaction diffusion systems of the FitzHugh-Nagumo type with hereditary memory and a very large class of nonlinearities, which have no restriction on the upper growth of the nonlinearity. We first prove the existence and uniqueness of weak solutions to the initial boundary value problem for the above-mentioned model. Next, we investigate the existence of a uniform attractor of this problem, where the time-dependent forcing term h ∈ L²_b(ℝ; H^-1(ℝ^N)) is the only translation bounded instead of translation compact. Finally, we prove the regularity of the uniform attractor A, i.e., A is a bounded subset of H²(ℝ^N) × H¹(ℝ^N) × L²_µ(ℝ⁺, H²(ℝ^N)). The results in this paper will extend and improve some previously obtained results, which have not been studied before in the case of non-autonomous, exponential growth nonlinearity and contain memory kernels.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.336-345
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• 2010

GS E&C was awarded the contract for the construction of Hanoi - Hai Phong Expressway Package EX-7 from Station Km 72+000 to Station Km 81+300 in December 2008. This project is the $7^{th}$ contract package of the 105.5 km long expressway near Hai Phong city, which includes a FCM-styled bridge along with high embankments over soft ground. For these high embankments, there is a need to treat the soft soil for improving the overall stability during construction and for reducing the post-construction settlement of the expressway. The Designer of this project had adopted four (4) different types of ground improvement techniques to treat the soft ground, including the prefabricated vertical drains (PVD), sand drains (SD), pack drains (PD, or sometimes called packed sand drains), and sand compaction piles (SCP). The main focus of soft soil treatment should be paid attention to the residual settlement after construction. In current design, however, it appeared that the secondary compression (or creep) of the improved soil layer and the consolidation settlement of the lower untreated compressible soil layer have been neglected in the estimation of the post-construction settlement. These uncalculated residual settlements may not only unsatisfy the design criteria but also raise serious problems during service period of this expressway. In this paper, the subsoil condition and current design were reviewed focusing on the employed soft soil treatment method and expected residual settlement.