• Journal of computational fluids engineering
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• v.14 no.4
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• pp.13-22
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• 2009

A two-phase (gas and liquid) flow analysis solver, named CUPID, has been developed for a realistic simulation of transient two-phase flows in light water nuclear reactor components. In the CUPID solver, a two-fluid three-field model is adopted and the governing equations are solved on unstructured grids for flow analyses in complicated geometries. For the numerical solution scheme, the semi-implicit method of the RELAP5 code, which has been proved to be very stable and accurate for most practical applications of nuclear thermal hydraulics, was used with some modifications for an application to unstructured non-staggered grids. This paper is concerned with the effects of interpolation schemes on the simulation of two-phase flows. In order to stabilize a numerical solution and assure a high numerical accuracy, the second-order upwind scheme is implemented into the CUPID code in the present paper. Some numerical tests have been performed with the implemented scheme and the comparison results between the second-order and first-order upwind schemes are introduced in the present paper. The comparison results among the two interpolation schemes and either the exact solutions or the mesh convergence studies showed the reduced numerical diffusion with the second-order scheme.

• Structural Engineering and Mechanics
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• v.57 no.2
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• pp.295-313
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• 2016

In this study, the three-dimensional finite element method is used to determine the stress intensity factor in Mode I and Mixed mode of a centered crack in an aluminum specimen repaired by a composite patch using contour integral. Various mesh densities were used to achieve convergence of the results. The effect of adhesive joint thickness, patch thickness, patch-specimen interface and layer sequence on the SIF was highlighted. The results obtained show that the patch-specimen contact surface is the best indicator of the deceleration of crack propagation, and hence of SIF reduction. Thus, the reduction in rigidity of the patch especially at adhesive layer-patch interface, allows the lowering of shear and normal stresses in the adhesive joint. The choice of the orientation of the adhesive layer-patch contact is important in the evolution of the shear and peel stresses. The patch will be more beneficial and effective while using the cross-layer on the contact surface.

• Journal of information and communication convergence engineering
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• v.11 no.3
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• pp.153-166
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• 2013

A hierarchical time division multiple access (HTDMA) medium access control (MAC) protocol is proposed for clustered mobile underwater acoustic networks. HTDMA consists of two TDMA scheduling protocols (i.e., TDMA1 and TDMA2) in order to accommodate mobile underwater nodes (UNs). TDMA1 is executed among surface stations (e.g., buoys) using terrestrial wireless communication in order to share mobility information obtained from UNs which move cluster to cluster. TDMA2 is executed among UNs, which send data to their surface station as a cluster head in one cluster. By sharing mobility information, a surface station can instantaneously determine the number of time slots in a TDMA2 frame up to as many as the number of UNs which is currently residing in its cluster. This can enhance delay and channel utilization performance by avoiding the occurrence of idle time slots. We analytically investigate the delay of HTDMA, and compare it with that of wellknown contention-free and contention-based MAC protocols, which are TDMA and Slotted-ALOHA, respectively. It is shown that HTDMA remarkably decreases delay, compared with TDMA and Slotted-ALOHA.

• Journal of Industrial Convergence
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• v.2 no.2
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• pp.47-68
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• 2004

The term "social marketing" was first introduced in 1971 to describe the use of marketing principles and techniques to advance a social cause, idea, or behavior. Social Marketing is a strategy for changing behavior. It utilizes concepts of market segmentation, consumer research, product concept development and testing, directed communication, facilitation, incentives, and exchange theory to maximize the target adopters' response. Social marketing requires knowledge of each target-adopter group, including its 1. social demographic characteristics, 2. psychological profile and 3. behavioral characteristics. To know the target adopters in these three related ways enables social marketer to make more accurate predictions. In addition to differentiating among and selecting target adopter groups, the social marketer will identify influence-holding groups, or influentials, who can affect a program's success. Great changes and opportunities exist to produce changes in the ways that individuals and groups think and behave and in meeting human needs. The balance of the scales of social change, we hope, will shift away from the use of force and violence to the use of persuasion and voluntary action. I trust that this dissertation will be useful highlighting the strategies and means of peaceful, planned social change designed to elevate the quality of life.

• Tribology and Lubricants
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• v.35 no.2
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• pp.106-113
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• 2019

We investigated the application of tetrahedral amorphous carbon (ta-C) coatings to fabricate a glass lens manufactured using a glass molding process (GMP). In this work, ta-C coatings with different thickness (50, 100, 150 and 200 nm) were deposited on a tungsten carbide (WC-Co) mold using the X-bend filter of a filtered cathode vacuum arc. The effects of thickness on mechanical and tribological properties of the coating were studied. These ta-C coatings were characterized by atomic force microscopy, scanning electron microscopy, nano-indentation measurements, Raman spectrometry, Rockwell-C tests, scratch tests and ball on disc tribometer tests. The nano-indentation measurements showed that hardness increased with an increase in coating thickness. In addition, the G-peak position in the Raman spectra analysis was right shifted from 1520 to $1586cm^{-1}$, indicating that the $sp^3$ content increased with increasing thickness of ta-C coatings. The scratch test showed that, compared to other coatings, the 100-nm-thick ta-C coating displayed excellent adhesion strength without delamination. The friction test was carried out in a nitrogen environment using a ball-on-disk tribometer. The 100-nm-thick ta-C coating showed a low friction coefficient of 0.078. When this coating was applied to a GMP, the life time, i.e., shot counts, dramatically increased up to 2,500 counts, in comparison with Ir-Re coating.

• Journal of information and communication convergence engineering
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• v.20 no.3
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• pp.143-152
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• 2022

The ongoing adoption of 5G will increase the data traffic, throughput, multimedia services, and power consumption for future wireless applications and services, including sensor and mobile networks. Multipath fading on wireless channels also reduces the system performance and increases energy consumption. To address these issues, device-to-device (D2D) and cooperative communications have been proposed. In this study, we propose two inter-clustering models using the relay selection method to improve system performance and increase energy efficiency in cooperative D2D networks. We develop two inter-clustering models and present their respective algorithms. Subsequently, we run a computer simulation to evaluate each model's outage probability (OP) performance, throughput, and energy efficiency. The simulation results show that inter-clustering model II has the lowest OP, highest throughput, and highest energy efficiency compared with inter-clustering model I and the conventional inter-clustering-based multirelay method. These results demonstrate that inter-clustering model II is well-suited for use in 5G overlay D2D and cellular communications.

• International journal of advanced smart convergence
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• v.11 no.4
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• pp.170-176
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• 2022

Given the critical importance of enhancing the level of ESG practices, the current research examines the impact of credit card users' pro-environmental characteristics (i.e., environmental self-accountability, eco-label involvement) on their satisfaction with credit card benefits related to green life. That is, this research investigates whether consumers' satisfaction with green credit card benefits varies depending on their environmental self-accountability and eco-label involvement. Specifically, we predict that (1) for consumers with high (vs. low) environmental self-accountability, their satisfaction with credit card benefits related to green life will be higher (hypothesis 1); and (2) when consumers have high (vs. low) eco-label involvement, they will be more likely to be satisfied with credit card benefits related to green life (hypothesis 2). An online survey (N = 293) was conducted to test the two hypotheses. In support of the hypotheses, the results indicate that (1) respondents who had high (vs. low) environmental self-accountability were more satisfied with credit card benefits related to green life, and (2) respondents with high eco-label involvement, as compared to those with low eco-label involvement, reported greater satisfaction with credit card benefits related to green life. We suggest an important insight into how credit card companies approaching ESG issues can increase their consumers' satisfaction with green credit card benefits, considering consumers' individual characteristics such as environmental self-accountability and eco-label involvement.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.2
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• pp.188-200
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• 2014

The IPCC 5th Assessment Report (Climate Change 2013: The Physical Science Basis) was accepted at the 36th Session of the IPCC on 26 September 2013 in Stockholm, Sweden. It consists of the full scientific and technical assessment undertaken by Working Group I. This comprehensive assessment of the physical aspects of climate change puts a focus on those elements that are relevant to understand past, document current, and project future of climate change. The assessment builds on the IPCC Fourth Assessment Report and the recent Special Report on Managing the Risk of Extreme Events and Disasters to Advance Climate Change Adaptation. The assessment covers the current knowledge of various processes within, and interactions among, climate system components, which determine the sensitivity and response of the system to changes in forcing, and they quantify the link between the changes in atmospheric constituents, and hence radiative forcing, and the consequent detection and attribution of climate change. Projections of changes in all climate system components are based on model simulations forced by a new set of scenarios. The report also provides a comprehensive assessment of past and future sea level change in a dedicated chapter. The primary purpose of this Technical Summary is to provide the link between the complete assessment of the multiple lines of independent evidence presented in the main report and the highly condensed summary prepared as Policy makers Summary. The Technical Summary thus serves as a starting point for those readers who seek the full information on more specific topics covered by this assessment. Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased. Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of $CO_2$ since 1750. Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system. Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions. The in-depth review for past, present and future of climate change is carried out on the basis of the IPCC 5th Assessment Report.

• Journal of the Korea Convergence Society
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• v.7 no.1
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• pp.97-104
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• 2016

This study was to examine relation of oral health knowledge and oral health behavior, targeting university students who major in health-related majors 198 students and health-unrelated majors 203 students. Oral health behavior by general characteristics appears most highest junior and senior sophomore, health-related major, regular dental check-up, dental education experience. 'It is effective in preventing bad breath brushing the tongue when brushing' of oral health knowledge reached 94.5% most highest. The health-related is high 'fluoride helps to prevent cavities.' 'Brushing tongue' of oral health behavior is most highest average 4.20. The health-related is high 'I know the brushing method that's right for me, and enforcement' and 'I am regular scaling for periodontal disease prevention'. To identify influence that general characteristics and oral health knowledge to oral health behavior, regression analysis result Y(oral health behavior)=2.692+0.377(regular dental check-up)+0.145(rental education experience)+ 0.215(method of oral health education)+0.045(oral health knowledge) was come out. Therefore, university students need to improve their oral health, structuring environment where information about oral health is reached out easily.

• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.119-124
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• 2019

Radiation therapy using flattening filter free beam can prevent beam attenuation caused by flattening filter and can improve treatment efficiency. However, accurate dose control is not established for nonuniform iso dose distributions. In this study, curved dosimeter based on photoconductive material $HgI_2$ was fabricated and its reproducibility and linearity were evaluated at 6 MV photon energy to verify its performance. In order to show the usefulness of the curved measurement, the signals measured on the flat substrate and the curved substrate were compared in the flattening filter free beam using the acrylic filter. As a result, the reproducibility of the unit cell dosimeter was evaluated as SE 0.613%, and the linearity was evaluated as R-sq 0.9999. The usability evaluation of the array curve dosimeter demonstrated its usefulness by indicating a curvature error rate of 11.073%p and a reduced error rate.