• Geomechanics and Engineering
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• v.32 no.5
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• pp.475-482
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• 2023

This paper studies the effect of the relaxation time on a two-dimensional thermoelastic medium which has a doubly porous structure in the presence of diffusion and gravity. The normal mode analysis is used to obtain the analytic expressions of the physical quantities, which we take the solution form in the exponential image. We have discussed a homogeneous thermoelastic half-space with double porosity with the effect of diffusion and gravity. The equations of generalized thermoelastic material with double porosity structure with one relaxation time have been developed. Moreover, the expressions of many physical quantities are explained. The general solutions, under specific boundary conditions of the problem, were found in some detail. In addition, numerical results are computed.

• KIEAE Journal
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• v.15 no.2
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• pp.123-131
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• 2015

Purpose : Improvement of indoor thermal comfort and reduction of the energy consumption in building can be obtained by applying a double skin facade system. In order to achieve effectively this purpose, design team would have to perform easy and appropriate performance analysis for making better design decision during the design process. Method : This paper focus on the natural ventilation performance of a multi-story type double skin facade with main causes which are pressure difference according to the wind and temperature difference between indoor and outdoor (Buoyancy Effect). Using this main causes, the natural ventilation ratio of wind effect-to-buoyancy effect in cavity of multi-story type double skin facade were analyzed through the performance analysis results of CFD (Computational Fluid Dynamics) simulation. Result : When the wind velocity was 2m/s, the ventilation rate in the cavity was highest. If wind velocity was slower than 2m/s wind velocity, buoyancy effect has more influence on the ventilation rate in the cavity, and if wind velocity was faster than 2m/s wind velocity, wind effect has more influence on the ventilation rate in the cavity.

• Human Ecology Research
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• v.61 no.3
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• pp.459-474
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• 2023

This study aimed to examine the effect of parentification on the smartphone dependency of upper elementary school children in double-income families and to verify whether ambivalence over emotional expression and loneliness sequentially mediates the relationship between parentification and smartphone dependency. The participants were 311 upper-elementary school students (4th to 6th graders; 126 boys, 40.5%) in doubleincome households residing in Seoul, Gyeong-gi, and Incheon. The data were collected through an online self-report questionnaire completed by the participants and were analyzed using SPSS 26.0 and Mplus 8.7 software. The results can be summarized as follows. Firstly, the direct effect of parentification on the smartphone dependency of the children from double-income families was statistically insignificant. Secondly, ambivalence over emotional expression mediated the effect of parentification on smartphone dependency, while loneliness did not. Lastly, parentification influenced smartphone dependency through the sequential mediating channel of ambivalence over emotional expression and loneliness. In conclusion, these findings indicate that interventions for smartphone-overdependent children from double-income families should place emphasis on children's psychological difficulties attributed to parentification. Specifically, this study highlights the importance of alleviating the levels of ambivalence over emotional expression and loneliness to address the issue of children's smartphone dependency in double-income families, suggesting possible involvement and support at both household and societal levels.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.51-51
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• 2010

We have proposed a new configuration for the improvement of neutron yield without the application of external ion sources in an inertial electrostatic confinement (IEC) device. The application of a double grid cathode to the IEC device is expected to generate a higher ion current than a single grid cathode. This paper verifies the effect of the double grid cathode by both fluid and particle simulation. Through the fluid simulation the optimal shape and applied voltage of the double grid cathode is determined, and through the particle simulation the usefulness of that is confirmed.

• Journal of the Optical Society of Korea
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• v.20 no.3
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• pp.427-430
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• 2016

The effect of the liquid density difference on interface shape of a double-liquid lens is analyzed in detail. The expressions of interface shape of two liquids with liquid density difference are analyzed and fitted with “even asphere”. The imaging analysis of the aspheric interface shape of a double-liquid lens is presented. The results show that the density difference of two liquids can cause the interface to be an aspheric surface, which can improve the image quality of a double-liquid lens. The result provides a new selection for the related further research and a wider application field for liquid lenses.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.289-300
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• 2019

We have conducted a preliminary numerical analysis to understand the effects of double-diffusive convection on the molar flux at the crystal region during the growth of mercurous bromide ($Hg_2Br_2$) crystals in 1 g and microgravity (${\mu}g$) conditions. It was found that the total molar fluxes decay first-order exponentially with the aspect ratio (AR, transport length-to-width), $1{\leq}AR{\leq}10$. With increasing the aspect ratio of the horizontal enclosure from AR = 1 up to Ar = 10, the convection flow field shifts to the advective-diffusion mode and the flow structures become stable. Therefore, altering the aspect ratio of the enclosure allows one to control the effect of the double diffusive natural convection. Moreover, microgravity environments less than $10^{-2}g$ make the effect of double-diffusive natural convection much reduced so that the convection mode could be switched over the advective-diffusion mode.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.300-301
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• 2004

Effect of refractive index difference between core and cladding on the characteristics of a vertical directional coupler using double sided deep ridge waveguide structure is investigated.

• Atmosphere
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• v.17 no.3
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• pp.231-240
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• 2007

The flow regimes of continuously stratified flow over a double mountain and the effects of a double mountain on wave breaking, upstream blocking, and severe downslope windstorms are investigated using a mesoscale numerical model (ARPS). According to the occurrence or non-occurrence of wave breaking and upstream blocking, three different flow regimes are identified over a double mountain. Higher critical Froude numbers are required for wave breaking and upstream blocking initiation for a double mountain than for an isolated mountain. This means that the nonlinearity and blocking effect for a double mountain is larger than that for an isolated mountain. As the separation distance between two mountains decreases, the degree of flow nonlinearity increases, while the blocking effect decreases. A rapid increase of the surface horizontal velocity downwind of each mountain near the critical mountain height for wave breaking initiation indicates that severe downslope windstorms are enhanced by wave breaking. For the flow with wave breaking, the numerically calculated surface drag is much larger than theoretically calculated one because the region with the maximum negative perturbation pressure moves from the top to the downwind slope of each mountain as the internal jump propagating downwind occurs.

• Advances in materials Research
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• v.7 no.3
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• pp.195-201
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• 2018

High Strength low alloy steels containing various levels of C, Nb and Mn were used and for each of which, a simulated double thermal cycle was applied with the same first peak temperature and different second peak temperatures to produce HAZ microstructure corresponding to multi-pass weld. Effect of double cycle second temperature on the microstructure was observed and compared with single cycle results obtained from previous works, it was found that the percentage of martensite austenite constituent (MA) increases by Nb addition for all steels with the same Mn content and the increase in Mn content at the same Nb content shows an increase in MA area fraction as well. MA area fraction obtained for the double cycle is larger than that obtained for the single cycle for all steels used which imply that MA will have great role in the brittle fracture initiation for double cycle and the inter-pass temperature should be controlled for medium and high-carbon Mn steel to avoid large area fraction of MA. The beneficial effects of Niobium obtained in single pass weld were not observed for the double cycle or multi pass welds.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.630-635
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• 2008

A dynamic model has been developed to investigate the operability of a single and double-effect solar energy assisted parallel type absorption chiller. In the study, main components and fluid transport mechanism have been modeled. Flow discharge coefficients of the valves and the pumps were optimized for the double-effect mode with solar-heated water circulated. The model was run for the single mode with solar energy supply only and the solar/gas driving double effect mode. And the cases of the double mode with and without the solar energy were compared. From the simulation results, it was found that the present configuration of the chiller is not capable of regulating solution flow rates according to variable solar energy input. And the single mode utilizing the solar energy only is not practical. It is suggested to operate the system in the double mode and the flow rate control system adaptive to variable solar energy input has to be developed.