• International Journal of Fluid Machinery and Systems
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• v.4 no.2
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• pp.223-228
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• 2011

The performance characteristics of centrifugal pump were measured experimentally when running with tap water and drag-reducing surfactant (Octadecyl dimethyl amine oxide (OB-8)) solutions. Tests have been performed on five cases of surfactant solutions with different concentrations (0ppm (tap water), 200ppm, 500ppm, 900ppm and 1500ppm) and four different rotating speeds of pump (1500rpm, 2000rpm, 2500rpm and 2900rpm). Compared with tap water case, the experimental results show that the total pump heads for surfactant solution cases are higher. And the pump efficiency with surfactant solutions also increases, but the shaft power for surfactant solutions cases decreases compared to t hat for tap water. There exists an optimal temperature for surfactant solutions, which maximizes the pump efficiency.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.608-612
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• 2016

D-(+)-glucose (Glc) was added to the original Fricke polyvinyl alcohol-glutaraldehyde-xylenol orange (FPGX) hydrogel dosimeter system to make a more stable FPGX hydrogel three-dimensional dosimeter in this paper. Polyvinyl alcohol was used as a substrate, which was combined with Fricke solution. Various concentrations of Glc were tested with linear relevant fitting for optimal hydrogel production conditions. The effects of various formulations on the stability and sensitivity of dosimeters were evaluated. The results indicated that D-(+)-Glc, as a free radical scavenger, had a great effect on stabilizing the dose response related to absorbency and reducing the auto-oxidization of ferrous ions. A careful doping with Glc could slow down the color change of the dosimeter before and after radiation without any effect on the sensitivity of the dosimeter.

• Polymer(Korea)
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• v.31 no.5
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• pp.436-441
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• 2007

In this work, the multiwalled carbon nanotubes(MWNTs) were functionalized with sodium dodecylbenzene sulfonate(SDBS) and then MWNTs/Lyocell composite fibers were prepared. The properties of MWNTs, the functionlization on the surface of MWNTs and their dispersion in the cellulose matrix were characterized by TEM, SEM, WAXD and FT-IR. The results showed that SDBS has been coated successfully onto the surface of the MWNTs by functionlization. This can improve effectively the dispersion uniformity of MWNTs in NMMO aqueous solution and is helpful to prepare a spinnable spinning dope. Moreover, the resultant MWNTs/Lyocell composite fibers still have cellulose II crystal structure, and their tensile strength and initial modulus increased with the increasing draw ratio and reached the optimal value with adding 1 wt% MWNTs. The thermal stability of the composite fiber was also improved by the addition of the MWNTs.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.171-176
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• 2012

A novel chemiluminescence (CL) system was established for the determination of cytosine arabinoside (Ara-C) in pharmaceutical preparations. It was showed that a clear CL signal was observed when Eosin Y mixed with Fenton reagent. The CL intensity was decreased significantly when Ara-C was added to the reaction system and partially scavenged the hydroxyl radicals in the solution. The extent of decrease in the CL intensity had a good stoichiometrical relationship with the Ara-C concentration. Based on this, we developed a new method for the determination of Ara-C using a flow injection analysis (FIA) technique with CL detection. Under the optimal conditions, the linear range of Ara-C concentration was $6.0{\times}10^{-9}\sim1.0{\times}10^{-7}mol/L$ (R = 0.9982) with a detection limit of $7.6{\times}10^{-10}mol/L$ (S/N=3), the RSD was 5.6% for $6.0{\times}10^{-8}mol/L$ Ara-C (n = 11). The method was successfully applied to the determination of Ara-C in injection samples. The possible chemiluminescence reaction mechanism was discussed.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3259-3264
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• 2010

A label-free amperometric immunosensor has been proposed for the detection of myeloperoxidase (MPO) in human serum. To fabricate such an immunosensor, a composite film consisting of N,N-dimethylformamide (DMF), multiwall carbon nanotubes (MWCNTs) and 1-ethyl-3-methyl imidazolium tetrafluoroborate ($EMIMBF_4$) suspension was initially formed on a glassy carbon electrode (GCE). Then cerium dioxide ($CeO_2$) dispersed by chitosan was coated on the GCE. After that, MPO antibodies (anti-MPO) were attached onto the nano$CeO_2$ surface. With a noncompetitive immunoassay format, the antibody-antigen complex formed between the immobilized anti-MPO and MPO in sample solution. The immunosensor was characterized by cyclic voltammetry, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The factors influencing the performance of the immunosensor were studied in detail. Under optimal conditions, the current change before and after the immunoreaction was proportional to MPO concentration in the range of 5 to $300\;ng\;mL^{-1}$ with a detection limit of $0.2\;ng\;mL^{-1}$.

• Journal of Korea Trade
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• v.23 no.2
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• pp.59-75
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• 2019

Purpose - The International Maritime Organization (IMO) has promulgated strict regulations on emissions in the maritime shipping industry. LNG (Liquefied Natural Gas) is, therefore, recognized as the optimal fuel alternative solution. The aim of this study is to select the most suitable location for an LNG bunkering port. This is formulated as a multiple-criteria ranking problem regarding four candidate ports in South Korea: the ports of Busan, Gwangyang, Incheon, and Ulsan. Design/Methodology/approach - An analysis employing the Consistent Fuzzy Preference Relation (CFPR) methodology is carried out, and the multiple-criteria evaluation of various factors influencing the location selection, such as the average loading speed of LNG, the number of total ships, the distance of the bunkering shuttle, and the degree of safety is performed. Then, based on the combination of both the collected real data and experts' preferences, the final ranking of the four ports is formulated. Findings - The port of Busan ranks first, followed by the ports of Gwangyang and Ulsan, with the port of Incheon last on the list. Originality/value - The Korean government could proceed with a clear vision of the candidate ports' ranking in terms of the LNG bunkering terminal selection problem.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.8
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• pp.2490-2506
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• 2022

In Mobile Edge Computing (MEC), attackers can speculate and mine sensitive user information by eavesdropping wireless channel status and offloading usage pattern, leading to user privacy leakage. To solve this problem, this paper proposes a Privacy-preserving and Energy-efficient Offloading Algorithm (PEOA) based on Lyapunov optimization. In this method, a continuous Markov process offloading model with a buffer queue strategy is built first. Then the amount of privacy of offloading usage pattern in wireless channel is defined. Finally, by introducing the Lyapunov optimization, the problem of minimum average energy consumption in continuous state transition process with privacy constraints in the infinite time domain is transformed into the minimum value problem of each timeslot, which reduces the complexity of algorithms and helps obtain the optimal solution while maintaining low energy consumption. The experimental results show that, compared with other methods, PEOA can maintain the amount of privacy accumulation in the system near zero, while sustaining low average energy consumption costs. This makes it difficult for attackers to infer sensitive user information through offloading usage patterns, thus effectively protecting user privacy and safety.

• International conference on construction engineering and project management
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• 2017.10a
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• pp.42-51
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• 2017

Due to the high degree of mechanization and the good environmental benefits, the prefabricated buildings are being promoted in China. The construction site layout of the prefabricated buildings has important influence on its safety benefit. However, few scholars have studied the safety problem on it. Firstly, in order to give a follow-up study foreshadowing the characteristics of prefabricated buildings are analyzed, the research assumptions are given and three types of safety buffers are established. And then a mult-objective model for the prefabricated buildings site layout is presented: taking into account the limits of noise, the coverage of the tower crane and the possibility of exceeding boundaries and overlapping, the constraints are and designed established respectively; Based on the improved System Layout Planning (SLP) method, the efficiency\cost\safety interaction matrices among the facilities are also founded for objective function. For the sake of convenience, a hypothetical facility layout case of the prefabricated building is used, the optimal solution of that is obtained in MATLAB with particle swarm algorithm (PSO), which proves the effectiveness of the model presented in this paper.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.1
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• pp.211-232
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• 2024

In this paper, we consider the resource allocation and offloading decisions of device-to-device (D2D) cooperative UAV-assisted mobile edge computing (MEC) system, where the device with task request is served by unmanned aerial vehicle (UAV) equipped with MEC server and D2D device with idle resources. On the one hand, to ensure the fairness of time-delay sensitive devices, when UAV computing resources are relatively sufficient, an optimization model is established to minimize the maximum delay of device computing tasks. The original non-convex objective problem is decomposed into two subproblems, and the suboptimal solution of the optimization problem is obtained by alternate iteration of two subproblems. On the other hand, when the device only needs to complete the task within a tolerable delay, we consider the offloading priorities of task to minimize UAV computing resources. Then we build the model of joint offloading decision and power allocation optimization. Through theoretical analysis based on KKT conditions, we elicit the relationship between the amount of computing task data and the optimal resource allocation. The simulation results show that the D2D cooperation scheme proposed in this paper is effective in reducing the completion delay of computing tasks and saving UAV computing resources.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1164-1183
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• 2019

The rapid development of cloud computing and high requirements of operators requires strong support from the underlying Data Center Networks. Therefore, the effectiveness of using resources in the data center networks becomes a point of concern for operators and material for research. In this paper, we discuss the online virtual-cluster provision problem for multiple tenants with an aim to decide when and where the virtual cluster should be placed in a data center network. Our objective is maximizing the total revenue for the data center networks under the constraints. In order to solve this problem, this paper divides it into two parts: online multi-tenancy scheduling and virtual cluster placement. The first part aims to determine the scheduling orders for the multiple tenants, and the second part aims to determine the locations of virtual machines. We first approach the problem by using the variational inequality model and discuss the existence of the optimal solution. After that, we prove that provisioning virtual clusters for a multi-tenant data center network that maximizes revenue is NP-hard. Due to the complexity of this problem, an efficient heuristic algorithm OMS (Online Multi-tenancy Scheduling) is proposed to solve the online multi-tenancy scheduling problem. We further explore the virtual cluster placement problem based on the OMS and propose a novel algorithm during the virtual machine placement. We evaluate our algorithms through a series of simulations, and the simulations results demonstrate that OMS can significantly increase the efficiency and total revenue for the data centers.