• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.245-255
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• 2021

This study is an empirical study on how factors such as social factor, entertainment factor on the Wechat social media platform affect users' flow and addiction to use. Researchers thought that despite the increasing addiction of social media Wechat users, existing social media research is limited to service quality and satisfaction, so research on user flow and addiction is necessary. Therefore, the researchers try to through empirical analysis, the WeChat use to addiction path to social factor (social interactivity, payable) and entertainment factor (entertainment, life relevance), examine how WeChat user experience affects the use intention and satisfaction, and determine its role in the user's WeChat addiction and flow, and tested. The results of this study are expected to provide a new theoretical basis for future research on addiction use of social media.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.8-15
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• 2004

Since the vehicle is regarded as the third living space, the comfortable conditions are required in the passenger compartment. For this reason, customers are concerned about the filtering performances and the importance of filter media has been greatly placed. Therefore the dust holding capacity, the efficiency of these filter media (dry paper, wet paper, non-woven) and the configuration of air filter for vehicle were measured in this study. The following results were obtained on the basis of air filter test. It shows that the thickness and poresize of filter media should be lower for the higher efficiency. The measurement result shows that the performance of round shape filters are higher than the square shape filters. The dust holding capacity of the wet paper and the non-woven paper is higher than the dry paper. As a result, this research can provide an important design parameter and product guidance of the intake air filter for vehicular engine.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.67.1-67.1
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• 2010

Understanding the nature of MHD turbulence is of fundamental importance in astrophysics. The results of these studies can be used to develop the star formation theory. While most of previous studies have considered turbulence in uniform media, the stratification of media can play an important role. We performed three-dimensional numerical simulations of isothermal, compressible, MHD turbulence with different plasma beta's and different flow Mach numbers in stratified media to study the effects of stratification on turbulence. We found Statistics of turbulent flow in stratified media is different from in uniform media. In this talk, we present the statistical properties of the MHD turbulence, such as the PDF, power spectrum, and structure function.

• Journal of ILASS-Korea
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• v.24 no.3
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• pp.122-129
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• 2019

Flow uniformity in aftertreatment system is an important factor in determining uniform catalytic reaction and filtration. In this study, variety types of DOC-DPF system design were analyzed to increase flow uniformity. For this analysis, ANSYS Fluent was used with porous media setup for DOC and DPF. Turbulent flow was modeled by standard $k-{\varepsilon}$ model excepting porous media. Uniformity index was utilized to evaluate the flow uniformity quantitatively. Reference design showed low velocity region because two large vortex were generated before baffle. When radius of DOC-DPF system was increased, exhaust pressure acting on the inlet decreases and velocity distribution was shifted to one side. When inlet pipe was set to axial center of DOC-DPF system velocity distribution was symmetric. However, flow was not dissipated until the front end of DOC and showed higher uniformity index. When the volume of DOC was reduced while fixed volume of entire DOC-DPF system and baffle plate is located downstream of the DOC-DPF system, there was improvement in uniformity index.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.20 no.3
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• pp.243-259
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• 2016

The Richards equation for water movement in unsaturated soil is highly nonlinear partial differential equations which are not solvable analytically unless unrealistic and oversimplifying assumptions are made regarding the attributes, dynamics, and properties of the physical systems. Therefore, conventionally, numerical solutions are the only feasible procedures to model flow in partially saturated porous media. The standard Finite element numerical technique is usually coupled with an Euler time discretizations scheme. Except for the fully explicit forward method, any other Euler time-marching algorithm generates nonlinear algebraic equations which should be solved using iterative procedures such as Newton and Picard iterations. In this study, lumped mass and distributed mass in the frame of Picard and Newton iterative techniques were evaluated to determine the most efficient method to solve the Richards equation with finite element model. The accuracy and computational efficiency of the scheme and of the Picard and Newton models are assessed for three test problems simulating one-dimensional flow processes in unsaturated porous media. Results demonstrated that, the conventional mass distributed finite element method suffers from numerical oscillations at the wetting front, especially for very dry initial conditions. Even though small mesh sizes are applied for all the test problems, it is shown that the traditional mass-distributed scheme can still generate an incorrect response due to the highly nonlinear properties of water flow in unsaturated soil and cause numerical oscillation. On the other hand, non oscillatory solutions are obtained and non-physics solutions for these problems are evaded by using the mass-lumped finite element method.

• Journal of Drive and Control
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• v.19 no.1
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• pp.62-68
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• 2022

Considering the characteristics of industrial machines that lack vehicle-induced wind, forced convection by a cooling fan is mostly required. Therefore, numerical analysis of an engine room is usually performed to examine the cooling performance in the room. However, most engine rooms consist of a number of parts and components at specific positions, leading to high costs for numerical modeling and simulation. In this paper, a new methodology for three-dimensional computer-assisted design simplification was proposed, especially for the pile of components and parts at the engine room outlet. A porous media model and regression analysis were used to derive a meta-model for imitating the flow rate reduction at the outlet by the pile. The results showed that the fitted model was reasonable considering the coefficient of determination. The final numerical model of the engine room was then used to simulate the velocity distribution by changing the mass flow rate at the outlet. The results showed that both velocity distributions were significantly changed in each case and the meta-model was valid in imitating the flow rate reduction by some piles of components and parts.

• Journal of Digital Convergence
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• v.16 no.4
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• pp.313-319
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• 2018

This experimental research explores the effect of drone's moving image on media audience's flow, arousal of interest and emotional state. Most previous researchers of media image effect insisted that camera movement should be abstained in order to give audience the feeling that movement of figures is in the contents story itself. and camera movement also can disturb natural viewing of audience. For the purpose of finding the effect of drone's moving image on media audience's flow, arousal of interest and emotional state, 2 groups of subjects composed of 56 university students were exposed to 2 different video clips, one with moving drone's image, the other with hovering drone's image. After this experiment, Questions which were designed to measure audience's flow, arousal of interest and emotional state were asked and analysed. This research found that subjects exposed to moving drone's image felt more interested and more positive emotional state than subjects exposed to hovering drone's image. However meaningful effect of drone's moving image on audience's flow was not found.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.241-246
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• 2000

Gas hydrates are solid solutions when water molecules are linked through hydrogen bondin create host lattice cavities that can enclose a large variety of guest gas molecules. The natural hydrate crystal may exist at low temperature above the normal freezing point of water and pressure greater than about 30 bars. A lot of quantities of natural gas hydrates exists in the ear many production schemes are being studied. In the present investigation, depressurization method considered to predict the production of gas and the simulation of the two phase flow - gas and - in porous media is being carried out. The simulation show about the fluid flow in porous have a variety of applications in industry. Results provide the appearance of gas and water prod the pressure profile, the saturation of gas/ water/ hydrates profiles and the location of the pl front.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1668-1678
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• 1997

Numerical analyses were performed to investigate the characteristics of regenerator in oscillating flow by using moving boundary method and Darcy model. In this work, periodic adiabatic boundary condition was suggested as the boundary condition of adiabatic part so that the effects of the thermal inertia of the wall could be considered. In carrying out numerical analyses, two models were applied and compared. One called isotropic model has the same thermal conductivity in radial and axial directions within a porous media. The other called aeolotropic model has different conductivity in each directions. Isotropic model could not show the advantage of energy reduction which needs to maintain constant wall temperature difference between heater and cooler. But aeolotropic model could simulate the reduction of energy consumption.

• FLOWER RESEARCH JOURNAL
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• v.16 no.3
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• pp.205-210
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• 2008

Sedum kamtschaticum has been used as one of the native valuable plants for ornamental purpose. This experiment was conducted to find out the optimum media for pot cultured Sedum kamtschaticum using peatmoss and coir-based mixtures. Four mixtures such as peatmoss:perlite(5:5, v/v), peatmoss:perlite(7:3, v/v), coir:perlite(5:5, v/v), and coir:perlite(7:3, v/v) were used. Plants were irrigated with a Sonneveld solution in an ebb & flow system. The content of T-N, K, and Ca in the peatmoss-based media was higher than those of the coir-based media. The concentration of T-N, K, and Ca in the shoots of Sedum kamtschaticum increased when plants were cultured with peatmoss-based media. In the peatmoss-based media, plant growth, such as number of branches, leaf length and shoot fresh and dry weights, were significantly increased than those of plant grown in the coir-based media. As the results, the optimum media for pot cultured Sedum kamtschaticum in an ebb & flow system was considered to be the peatmoss-based mixtures.