• Journal of the Korean institute of surface engineering
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• v.56 no.1
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• pp.1-11
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• 2023

Lubricant-impregnated nanoporous surfaces (LIS), which is created by impregnating water-immiscible oil into nanoporous surface structure, have been explored considering wide range of application fields. Due to the lubricant impregnated in nanoporous structure, the surface shows extreme de-wetting with a high mobility of water droplets, so that various functionalities can be realized. The lubricant layer inhibits the contact of corrosive media to porous structure as well as metal substrate, thus the surface improves the corrosion resistance. The water on the surface freeze without any contact to solid porous structure, showing a low ice adhesion for de-icing an anti-icing. The extremely high mobility of water droplets on lubricant-impregnated porous surfaces also contributes the enhancement of condensation heat transfer as well as water harvesting from fog and moisture. Moreover, the bacteria adhesion on metal surface forming biofilms causing serious hygiene issues can be inhibited on the lubricantimpregnated surfaces. Despite of such superior functionalities, the lubricant-impregnated porous surface has a limitation of lubricant depletion by external flow of fluids. Therefore, extensive efforts to improve the durability of lubricant-impregnated surface are required for practical applications.

• Journal of the Korean Society of Clothing and Textiles
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• v.46 no.6
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• pp.963-986
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• 2022

This article surveys the fashion forecasting industry in Korean domestic markets. With the rise of new media and devices with high technology, the paradigm of fashion trends forecasting systems has dramatically changed. New perspectives of trend forecasting are required to understand the trend flow and consumer behavior of the MZ generation. The research questions are as follows: 1) Major trend forecasting companies studied the development of their strategies and new forecasting methods. 2) The consumers' needs in the domestic market were analyzed. The influence of the trend companies' forecasting on the market was investigated. The results are as follows: 1) International trend forecasting significantly affected the domestic market. The concordance rate between consumers' online searches about fashion trends was approximately 70.14%. The match rate by category is as follows: The highest rate, 85.06% is from pattern and print, color is 83.92%, the item is 80.39%, and style is 54.32%. 2) Specialized information such as the Pantone color chart is being widely consumed, leading to a trend among the masses. 3) The Korean-specific socio-cultural background has an impact on domestic trends.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.410-412
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• 2021

Recently, the amount of information and content has increased dramatically. Users can easily obtain recipe through various media. In addition, the water purifier market is growing without a downward trend and demand for more convenient and smart water purifiers are increasing. By using a smart water purifier with application, each individual can improve the quality of the dish by using a certain amount of water that each person prefers. A solenoid valve was used to allow only the amount of water set by individual to flow out and a solenoid valve and smartphones were linked using Bluetooth communication while using smartphone applications developed when setting the amount of water.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.959-965
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• 2024

The High Temperature Test Unit (HTTU) was an experimental set-up to conduct separate and integral effects tests of the Pebble Bed Modular Reactor (PBMR) core. The annular core consisted of a randomly packed bed of uniform spheres. Natural convection tests using both nitrogen and helium, and forced convection tests using nitrogen, were conducted. The maximum material temperature achieved during forced convection testing was 1200 ℃. This paper presents the numerical analysis of the flow and temperature distribution for a forced convection test using 3D CFD as well as a 1D systems-CFD computer code. Several modelling approaches are possible, ranging from a fully explicit to a semi-implicit method that relies on correlations of their associated phenomena. For the comparison between codes, the analysis was performed using a porous media approach, where the conduction and radiative heat transfer were lumped together as an effective thermal conductivity and the convective heat transfer was correlated between the solid and gas phases. The results from both codes were validated against the experimental measurements. Favourable results were obtained, in particular by the systems-CFD code with minimal computational and time requirements.

• Journal of Wetlands Research
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• v.14 no.1
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• pp.75-87
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• 2012

Hyporheic zone is a region beneath and alongside a stream, river, or lake bed, where there is mixing of shallow groundwater and surfacewater. Hyporheic exchange controls a variety of physical, biogeochemical and thermal processes, and provides unique ecotones in a aquatic ecosystem. Field and experimental observations, and modeling studies indicate that hyporheic exchange is mainly in response to pressure gradients driven by the geomorphological features of stream beds. In the reach scale of a stream, pool-riffle structures dominate the exchange patterns. Flow over a pool-riffle sequence develops recirculation zones and stagnation points, and this flow structures make irregular pressure gradient which is driving force of the hyporheic exchange. In this study, 3 D hydro-dynamic model solves the Reynolds-averaged Navier-Stokes equations for the surface water and Darcy's Law and the continuity equation for ground water. The two sets of equations are coupled via the pressure distribution along the interface. Simulation results show that recirculation zones and stagnation points in the pool-riffle structures dominantly control the upwelling and downwelling patterns. With decrease of recirculation zones, length of donwelling zone formed in front of riffles is reduced and position of maximum downwelling point moves downward. The numerical simulation could successfully predict the behavior of hyporheic exchange and contribute the field study, river management and restoration.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.149-156
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• 2020

Permeation grouting effectively enhances soil strength and decreases permeability of soil; however, the flow of grout is heavily affected by anisotropy of hydraulic conductivity in layers. Therefore, this study investigates the effect of permeability anisotropy on the effective radius of horizontal permeation grout using computational fluid dynamics (CFD). We modeled the horizontal permeation grout flow as a two-phase viscous fluid flow in porous media, and the model incorporated the chemical diffusion and the viscosity variation due to hardening. The numerical simulation reveals that the permeability anisotropy shapes the grout bulb to be elliptic and the dissolution-driven diffusion causes a gradual change in grout pore saturation at the edge of the grout bulb. For the grout pore saturations of 10%, 50% and 90%, the horizontal and vertical radii of grout bulb are estimated when the horizontal-to-vertical permeability ratio varies from 0.01 to 100, and the predictive model equations are suggested. This result contributes to more efficient design of injection strategy in formation layers with permeability anisotropy.

• Tunnel and Underground Space
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• v.16 no.4 s.63
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• pp.281-287
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• 2006

Intake of groundwater by tunneling in a mountainous area mostly results from groundwater flow through fractured parts of total rock mass. For reasonable analysis of this phenomenon the representative joint groups 1, 2, and 3 have been selected by previous investigations, geological/geophysical field tests and boring works. Three dimensional fractures were generated by the FracMan and MAFIC which is a three dimensional finite element model has been used to analyse a groundwater flow through fractured media. Monte Carlo simulation was applied to reduce the uncertainty of this study. The numerical results showed that the average and deviation of amounts of groundwater intaked into tunnel per unit length were $5.40{\times}10^{-1}$ and $3.04{\times}10^{-1}m^3/min/km$. It is concluded that tunnel would be stable on impact of groundwater environment by tunneling because of the lower value than $2.00{\sim}3.00m^3/min/km$ as previous and present standard on the application of tunnel construction.

• Journal of Korean Society on Water Environment
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• v.33 no.1
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• pp.1-7
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• 2017

Bioretention systems, an advance low impact development and green infrastructure approach were currently utilized in different parts of the world because it promotes biodiversity thereby mimicking and preserving the pre-developed state of an area. This study investigated and compared the capability of four bioretention systems to identify factors affecting the hydraulic capabilities and pollutant removal efficiencies of each system. The two bioretention type A referred as Type A-C and Type A-FC were planted with perennials such as Chrysanthemum and Fan columbine, respectively. On the other hand, the two type B bioretention systems referred as Type B-A and Type B-JM were planted with shrub plant species such as Azalea and Japanese Meadowsweet, respectively. Based on the results, TV, infiltration mechanism, filter media depth and plant species were identified as the factors affecting the difference in flow attenuation, retained volume and pollutant removal efficiency of Type A-C, Type A-FC, Type B-A and Type B-JM bioretention systems. The design of bioretention Type B-A and Type B-JM were advantageous considering greater volume retention, groundwater recharge, longer HRT and peak flow attenuation and greater pollutant removal efficiency. On the other hand, the design of bioretention Type A-C and Type A-FC was more appropriate for design considering reduced groundwater contamination.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.101-104
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• 2003

In this study based on the mass transfer theory, experiments for the evaporation rates depending on various conditions were carried out through the operation of the existing Natural Evaporation Facility in KAERI. Evaporation media were made of the cotton and polyester. Air circulation in the facility was forced by exhausting fans. The evaporation rate and the decontamination factor were calculated by the result of experiment. The evaporation rate increased as the flow rate of air supply, the feed rate of liquid waste, and the temperature of supplied air increased. As for the humidity of supplied air, the evaporation rate was getting higher as the humidity was getting lower. As the result of this study, operation conditions of the Natural Evaporation Facility are optimized as follows : The air temperature above $8^{\circ}C$, the air humidity below 70%, the air flow rate 1.14-1.47 m/sec, and the liquid waste feed rate $4.6{\ell}/hr\cdotm^2$. The decontamination factor and the radioactivity are $5.1{\times}10^3$and $4.7{\times}10^{-13}{\mu}Ci/\textrm{m}{\ell}$ respectively, at the above mentioned optimum operation conditions. The air factor in the Dalton's equation for evaporation was determined from results of experiment on the temperature, the humidity, and the flow rate of supplied air as following : $[\textit{Eh}=(0.018 + 0.0141\textitv) {\delta}textitH]$

• Journal of Korea Entertainment Industry Association
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• v.14 no.6
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• pp.91-107
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• 2020

The purpose of this study is to explore quantitatively the success factors of YouTube's music cover channel. Along the process, constructing and testing the measurement for music cover channel's characteristics. The research constructed the measurement items based on results of qualitative studies. To perform the purposes the study suggest a research model which integrated the Post Acceptance Model with five music cover channel's characteristics based on the recent case studies. The five characteristics were contents, video, creator, interactivity, and publicity. The characteristics were integrated with Post Acceptance Model. After testing reliability and validity the research model was revised then, the research hypothesis was tested. The research results show: first, it was found that the content characteristics did not meet the expected value of users. Second, among the five factors of channel characteristics presented in creator's characteristics have the largest effect on user's value perception Third, in the factor analysis process, the content factor and the video were loaded on the same factor thus integrated as one factor. Fourth, satisfaction and intention for continual usage were also loaded on the same factor thus integrated as one factor. The research results suggest that music cover channel operators need to enhance the creator's attraction, communication with user, and publicity in various ways.