• The KSFM Journal of Fluid Machinery
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• v.15 no.3
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• pp.25-31
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• 2012

A computational study on the improvement of the pressure loss of intake system, which is located at engine manifold of the combat vehicle, has been conducted using a finite-volume-based, Reynolds-Averaged Navier-Stokes (RANS) solver. The computational result of the pressure loss through the air cleaner is in good agreement with equivalent experimental data. A parametric study was done for improving of the pressure loss of intake system over the baseline case. The effects of five primary parameters such as the height of inlet, the width of interconnection pipe, the shape of drain chamber and the diameter of filter housing were considered in this study. Consequently, this computational investigation can contribute to finding an optimal guideline for the idea of improvement in the pressure loss of intake system.

• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.76-80
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• 2000

Electrochemical oxidation of ethanol has been studied at nickel and $RuO_2-modified$ nickel electrodes in 1 M KOH using electrochemical impedance spectroscopy. Equivalent circuits have been worked out from simulation of impedance data to model oxidation of ethanol as well as the passivation of the electrode. The charge-transfer resistances for oxidation of these electrodes became smaller in the presence of ethanol than in its absence. The nickel substrate facilitated ethanol oxidation at $RuO_2-modified$ nickel electrodes. We also describe the Performance of nanosized electrocatalysts of the same composition in comparison to those of the bulk electrodes. The nanosized electrodes were obtained by electrode-positing the alloy from complexed form of these metal ions with fourth and fifth generation polyamidoamine dendrimers.

• Journal of Broadcast Engineering
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• v.16 no.5
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• pp.824-833
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• 2011

In this paper, using the Rec. ITU-R P.1546 explaining a propagation prediction model in the VHF and UHF bands, we propose the analytical methodology for calculating the service distance and field strength for analogue and digital TV receivers. From the derived formulation of the receiver field strength, some computation results are presented and discussed in terms of the equivalent level of service caused by analogue to digital TV conversion. The suggested method is also applicable to the analysis of frequency coordination or compatibility from unwanted signal in VHF and UHF bands.

• Journal of Broadcast Engineering
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• v.8 no.1
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• pp.11-18
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• 2003

In this paper, we introduce a novel signal quality enhancement algorithm with a perceptual interference analysis and perceptual convolutional noise suppression. A perceptual convolutional noise is reflected in the audible disturbance that can still be recognized after the additional noise suppression and tonality change which is caused by the noise energy excitation. The enhancement system is organized with a perceptual additional noise suppression part and a perceptual convolutional noise suppression part. Experimental results show that these two parts have an equivalent quality enhancement performance.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.11a
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• pp.115-116
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• 2009

In this study, near-infrared absorbing dyes, namely, new rigidified heptamethine cyanine dyes were synthesized and investigated their properties. The cyanine dyes have been synthesized by a condensation reaction between a quanternary salt containing as activated methyl group and an unsaturated bisaldehyde or its equivalent. We were investigated the synthesis of new rigidified heptamethine cyanine and related the compounds with near infrared absorption. The full spectroscopic characterization of all cyanine were described. Absorption properties in the near-infrared region may cause these dyes to the potential used in bio-probe, optical recording media materials.

• Geomechanics and Engineering
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• v.21 no.1
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• pp.85-93
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• 2020

In this article, the generalized thermoelastic theory with fractional derivative is presented to estimate the variation of temperature, the components of stress, the components of displacement and the changes in volume fraction field in two-dimensional porous media. Easily, the exact solutions in the Laplace domain are obtained. By using Laplace and Fourier transformations with the eigenvalues method, the physical quantities are obtained analytically. The numerical results for all the physical quantities considered are implemented and presented graphically. The results display that the present model with the fractional derivative is reduced to the Lord and Shulman (LS) and the classical dynamical coupled (CT) theories when the fractional parameter is equivalent to one and the delay time is equal to zero and respectively.

• Korean Journal of Comparative Education
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• v.24 no.3
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• pp.127-156
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• 2014

This study was inspired by the issue that the fundamentals of education have been overlooked, as today's smart education policies established in the knowledge-based information society of the 21st century have only focused on building digital environment and its efficiency. To carry out the study, the media education of Germany, which is equivalent of Korea's smart education, was analyzed to obtain implications for Korea's smart education. In Germany, the media education has been managed by the country ever since the information society has begun. Since 2009, the media education has become a requirement for all schools in every state. Thus, the current media education policy of each state has been analyzed, which revealed the following common characteristics. 1) The media education is closely linked to existing curriculum and education, rather than being conducted separately with different standards. 2) The media education is being conducted in a democratic manner by actively reflecting the exemplary cases of school teachers, rather than following the instructions and guidelines from the government. 3) The media education deals with the character and identity of young students, based on their basic understanding of information society, which are essential for a successful life in the upcoming society. Unlike the first and second implication linked to the method and procedure of media education policy, the third implication is the basic purpose of media education, which is also the key implication of this study. The media education policy of Germany, which is being conducted with its own educational philosophy, offers significant implications for Korea's smart education policy. In Korea, the education only revolves around device-based environment innovation or content development. It should be noted that the purpose of smart education is developing smart individuals who can bring better, happier, and more successful society - rather than establishing a smart environment. Therefore, the focus of discussion on Korea's smart education that revolves around environment, infrastructure, device utilization, and contents development should be changed to the character and identity of students, which are required in the future smart era. That's when 'human-based' educational revolution, instead of 'device-based' classroom revolution can begin.

• Korean journal of communication and information
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• v.41
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• pp.145-180
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• 2008

This study tries to test time reallocation hypothesis proposed by Lee(2005) that claims the time use pattern as a whole has changed as new media is introduced-in this case, internet-in our daily lift. It has been pointed out that researches, confined to study whether time use for traditional media is displaced by a new media, have such a limitation as 'media isolationism' and resulted in incoherent conclusions. In order to verify time reallocation hypothesis, which explains the influence of internet use on daily activities with broad perspectives, this research employed two different methods. First, this study analyzed the differences of time use patterns of daily activities and media use behaviors between internet users and non-users by using t-test. Second, logistic regression was used to confirm that the difference of time use pattern between internet users and non-users in many daily activities. The results show that time use pattern for daily activities has reorganized In the most of the age groups. Especially, in the young age groups, time reallocation by internet appeared more obvious than the equivalent old age groups.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.229-238
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• 2017

This study started to deduce a permeability relationship that can consider the geometric features of various porous media under different flow regimes. With reference to the previous works of Kozeny and Carman, the conventional Darcy-Weisbach relation (Darcy's friction flow equation) was reviewed and expanded for porous flow analysis. Based on the capillary model, this relation was transformed to the friction equivalent permeability (FEP) definition. The validity of the FEP definition was confirmed by means of comparison with the Kozeny-Carman equation. Hereby, it was shown that the FEP definition is the generalized form of the Kozeny-Carman equation, which is confined to laminar flow through a circular capillary. In conclusion, the FEP definition as a new permeability estimation method was successfully developed by expanding the Darcy-Weisbach relation for porous flow analyses.

• Tunnel and Underground Space
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• v.8 no.4
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• pp.275-286
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• 1998

The effective permeability and the representative element volume(REV) of fracture network model were evaluated based on the parameters such as permeability tensor, principal permeability and the direction of principal permeability. The effective permeability ranges between the harmonic mean and the arithmetic mean of the local permeabilities of subdivided blocks. From the numerical experiments, which were for investigating the influence of model volume on the variation of flux for the cubic models, it was found that the variation of flux became reduced as the model volume approached REV. The variation of groundwater flux into the tunnel in the fracture network model was mainly dependent on the ratio of the tunnel length to model size rather than REV. And it was found that groundwater flux into the tunnel was not completely consistent between the fracture network model and the equivalent porous media model, especially when the ratio of the tunnel length to model size is small.