• Journal of Powder Materials
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• v.24 no.3
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• pp.229-234
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• 2017

We report on a simple and robust route to the spontaneous assembly of well-ordered magnetic nanoparticle superstructures by irreversible evaporation of a sessile single droplet of a mixture of a ferrofluid (FF) and a nonmagnetic fluid (NF). The resulting assembled superstructures are seen to form well-packed, vertically arranged columns with diameters of $5{\sim}0.7{\mu}m$, interparticle spacings of $9{\sim}2{\mu}m$, and heights of $1.3{\sim}3{\mu}m$ The assembled superstructures are strongly dependent on both the magnitude of magnetic field and the mixing ratio of the mixture. As the magnitude of the externally applied magnetic field and the mixing ratio of the mixture increase gradually, the size and interspacing of the magnetic nanoparticle aggregations decrease. Without an externally applied magnetic field, featureless patterns are observed for the ${\gamma}-Fe_3O_4$ nanoparticle aggregations. The proposed approach may lead to a versatile, cost-effective, fast, and scalable fabrication process based on the field-induced self-assembly of magnetic nanoparticles.

• Membrane Journal
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• v.3 no.3
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• pp.136-139
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• 1993

It is well known that the membrane permeation in pervaporation is governed by both the chemical nature of the membrane material and the physical structure of the membrane and also the separation can be achieved by differences in either solubility, size or shape. The solubility of the penerrant in the polymeric membrane can be described qualitively by applying the Hildebrand relation [1] which relates the energy of mixing of the penerrant and the polymer material. Froehling et al. have tried to predict the swelling behavior of polymers for the systems of polyvinylchloride(PVC)-toluene-methanol, PVC-trichloroethylene-nitromethane and PVC-n-butylacetate-nitromethane[2]. The former two systems which do not show the donor/acceptor interactions upon mixing showed the successful results[2]. In addition to this technique, there are several other possible approaches to predict the swelling behaviors of polymers, such as the surface thermodynamic approach[3, 4], the comparison of the membrane polarity with the solvent polarity in terms of Dimroth's solvent polarity value[5].

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.252-259
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• 2001

Computational study has been performed to observe the flow characteristics of combustion chamber for geometrical modification in municipal solid waste incinerator. A series of geometrical modification has been carried out as an attempt to reduce the size of recirculation zone, to obtain uniform flow field in the secondary combustion chamber and to improve the mixing of combustion gas. Two dimensional non-reacting turbulent flow has been studied as the first step to get such goals and the result of design optimization is presented. In addition, three dimensional non-reacting and reacting flow analyses were performed to verify the validity of two dimensional approach.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.181-189
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• 1998

A numerical study based on the three-dimensional Reynolds averaged Navier-Stokes equations is presented to analyze the transonic flowfield through two-stage axial compressor. Explicit four-step Runge-Kutta scheme is used for solution algorithm, and local time step and implicit residual averaging are introduced for enhancing the convergency. Artificial dissipation model is adopted to assure the stability of solution. The solver is coupled with Baldwin-Lomax model to describe turbulence. To avoid calculating the unsteady flow, a mixing process is modeled at a station between rotating and stationary blade rows. Results show a variety of important physical phenomena. Comparison of the flowfields with and without tip clearance shows that the effect is considerable in this flowfield. Comparisons with experimental data carried out to validate the calculational results show reasonable agreements. Some remedies are also suggested to improve the revealed problems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.614-615
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• 2010

The propellants distribution of an oxidizer rich preburner was predicted by a simplified physical approach. The Mixing head is composed of honeycomb array of 7 fuel injectors and 24 oxidizer injectors. The OF ratio of the mixing head is 15. As results, the OF ratio of the central area is about 9 and the OF ratio of the wall area is about 30.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1625-1630
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• 2018

The recent neutrino experiment results show a preference on normal mass ordering of neutrinos. The global efforts to search for neutrinoless double beta decays undergo a broad gap with the approach to the prediction in three-neutrino framework based on the normal ordering. Current research is to show that it is possible to find a neutrinoless double beta decay signal even with normal ordered neutrino masses. We propose the existence of light sterile neutrino as a solution to the higher effective mass of electron neutrino expected by experiments under operation. A few short-baseline oscillation experiments gave rise to exclusion bound to the mass of sterile neutrino and its mixing with the lightest neutrino. It is demonstrated that results of neutrinoless double beta decays can also narrow down the ranges of the mass and the mixing angle of sterile neutrino.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.1945-1954
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• 2020

Subchannel code is one of the effective simulation tools for thermal-hydraulic analysis in nuclear reactor core. In order to reduce the computational cost and improve the calculation efficiency, empirical correlation of turbulent mixing coefficient is employed to calculate the lateral mixing velocity between adjacent subchannels. However, correlations utilized currently are often fitted from data achieved in central channel of fuel assembly, which would simply neglect the wall effects. In this paper, the CFD approach based on spectral element method is employed to predict turbulent mixing phenomena through gaps in 3 × 3 bare tight lattice rod bundle and investigate the flow pulsation through gaps in different positions. Re = 5000,10000,20500 and P/D = 1.03 and 1.06 have been covered in the simulation cases. With a well verified mesh, lateral velocities at gap center between corner channel and wall channel (W-Co), wall channel and wall channel (W-W), wall channel and center channel (W-C) as well as center channel and center channel (C-C) are collected and compared with each other. The obvious turbulent mixing distributions are presented in the different channels of rod bundle. The peak frequency values at W-Co channel could have about 40%-50% reduction comparing with the C-C channel value and the turbulent mixing coefficient β could decrease around 25%. corrections for β should be performed in subchannel code at wall channel and corner channel for a reasonable prediction result. A preliminary analysis on fluctuation at channel gap has also performed. Eddy cascade should be considered carefully in detailed analysis for fluctuating in rod bundle.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.467-474
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• 2017

Each river confluence has the inherent hydraulic and mixing characteristics coming from its bathymetry and topography. It is necessary to make the measurement covering the spatial extent of studying area in order to catch these 2-dimensional intrinsic characteristics. This study focuses to investigate the hydraulic and mixing characteristics at the confluence of Nakdong and Geumho River, from field measurement of flow, water quality, and suspended particle distribution with ADCP (Riversurveyor M9), multi-parameter water quality sonde (YSI6600V2), and submersible system for in-situ observations of particle size distribution and volume concentration (LISST : Laser In-Situ Scattering & Transmissometry), respectively. From the results, it can be found that the field measurement of suspended particle and water quality distribution can be the useful approach to catch the hydraulic and mixing characteristics at a river confluence.

• International Journal of Computer Science & Network Security
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• v.22 no.9
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• pp.334-342
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• 2022

Nowadays, as we can notice on social media, most users choose to use more than one language in their online postings. Thus, social media analytics needs reviewing as code-switching analytics instead of traditional analytics. This paper aims to present evidence comparable to the accuracy of code-switching analytics techniques in analysing the mood state of social media users. We conducted a systematic literature review (SLR) to study the social media analytics that examined the effectiveness of code-switching analytics techniques. One primary question and three sub-questions have been raised for this purpose. The study investigates the computational models used to detect and measures emotional well-being. The study primarily focuses on online postings text, including the extended text analysis, analysing and predicting using past experiences, and classifying the mood upon analysis. We used thirty-two (32) papers for our evidence synthesis and identified four main task classifications that can be used potentially in code-switching analytics. The tasks include determining analytics algorithms, classification techniques, mood classes, and analytics flow. Results showed that CNN-BiLSTM was the machine learning algorithm that affected code-switching analytics accuracy the most with 83.21%. In addition, the analytics accuracy when using the code-mixing emotion corpus could enhance by about 20% compared to when performing with one language. Our meta-analyses showed that code-mixing emotion corpus was effective in improving the mood analytics accuracy level. This SLR result has pointed to two apparent gaps in the research field: i) lack of studies that focus on Malay-English code-mixing analytics and ii) lack of studies investigating various mood classes via the code-mixing approach.

• International Journal of Computer Science & Network Security
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• v.21 no.6
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• pp.127-136
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• 2021

In the systems and software modeling field, a conceptual model involves modeling with concepts to support development and design. An example of a conceptual model is a description developed using the Unified Modeling Language (UML). UML uses a model multiplicity formulation approach, wherein a number of models are used to represent alternative views. By contrast, a model singularity approach uses only a single integrated model. Each of these styles of modeling has its strengths and weaknesses. This paper introduces a partial solution to the issue of multiplicity vs. singularity in modeling by adopting UML use cases and class models into the conceptual thinging machine (TM) model. To apply use cases, we adopt the observation that a use-case diagram is a description that shows the internal structure of the part of the system represented by the use case in addition to being useful to people outside of the system. Additionally, the UML class diagram is recast in TM representation. Accordingly, we develop a TMUML model that embraces the TM specification of the UML class diagram and the internal structure extracted from the UML use case. TMUML modeling introduces some of the advantages that have made UML a popular modeling language to TM modeling. At the same time, this approach supplies UML with partial model singularity. The paper details experimentation with TMUML using examples from the literature. Our results indicate that mixing UML with other models could be a viable approach.