• New & Renewable Energy
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• v.16 no.3
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• pp.13-26
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• 2020

This study analyzed whether the diffusion of new and renewable energy contributed to mitigating emissions of various air pollutants, including particulate matter, using panel econometric models. The theoretical foundation of such econometric models is based on the Environmental Kuznets Curve (EKC) hypothesis, which assumes an inverted U-shaped relation between national income and environmental pollution, as originally proposed by Grossman and Krueger. We examined whether there are inverted U-, U-shaped, or N-shaped relations between national income and air pollution. We demonstrate that increases in new and renewable energy significantly mitigated emissions of CO, NO_X, and PM2.5. Additionally, we included NO_X, SO_X, PM10, and VOCs as secondary emission sources of PM2.5 and found that emission of PM10 resulted in the highest PM2.5 emissions, followed by NO_X and SO_X emissions. The impact of new and renewable energy on air pollution varied across regions. Increase of new and renewable energy in the Honam region significantly mitigated CO, NO_X, and TSP emissions, while that in the Youngnam and metropolitan areas did not significantly mitigate air pollution overall. There was a U-shaped relationship between air pollution and national income for CO, NO_X, PM2.5, and SO_X, while an inverted N-shape was observed for PM10.

• Journal of Korean Academy of Nursing
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• v.50 no.3
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• pp.349-368
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• 2020

Purpose: This study aimed to identify parental factors associated with smartphone overuse in preschoolers. Methods: A systematic review was conducted according to PRISMA guidelines. Relevant studies published in peer-reviewed journals from 2009 to June 2019 were identified through systematic search in 10 electronic databases (PubMed, CINAHL, Cochrane Central, EMBASE, Web of Science, NDSL, KISS, KMbase, KoreaMed, and RISS). Standardized effect sizes were calculated to quantify the associations of parental factors with smartphone overuse in preschoolers using meta-analysis. Results: A total of 30 cross-sectional studies involving 7,943 participants met the inclusion criteria. The following were negatively correlated with smartphone overuse in preschoolers: mother's parenting self-efficacy (r=-.35), mother-child attachment (r=-.28), mother's positive parenting behavior (r=-.28), mother's positive parenting attitude (r=-.25), and father's parenting involvement (r=-.15). Further, maternal factors such as smartphone addiction tendency (r=.41), parenting stress (r=.40), negative parenting behavior (r=.35), negative parenting attitude (r=.14), smartphone usage time (r=.26), employment status (r=.18), and age (r=.12) were positively correlated with smartphone overuse in preschoolers. Conclusion: Several parental factors influence smartphone overuse in preschoolers. These findings emphasize the need to assess and enhance the parental factors identified in this study to prevent smartphone overuse in preschoolers. Accordingly, we recommend the development of preventive interventions to strengthen parent-related protective factors and mitigate risk factors.

• Advances in concrete construction
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• v.9 no.3
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• pp.313-326
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• 2020

Glass fiber-reinforced polymer (GFRP) bars have been introduced as an effective alternative for the conventional steel reinforcement in concrete structures to mitigate the costly consequences of steel corrosion. However, despite the superior performance of these composite materials in terms of corrosion, the effect of replacing steel reinforcement with GFRP on the seismic performance of concrete structures is not fully covered yet. To address some of the key parameters in the seismic behavior of GFRP-reinforced concrete (RC) structures, two full-scale beam-column joints reinforced with GFRP bars and stirrups were constructed and tested under two phases of loading, each simulating a severe ground motion. The objective was to investigate the effect of damage due to earthquakes on the service and ultimate behavior of GFRP-RC moment-resisting frames. The main parameters under investigation were geometrical configuration (interior or exterior beam-column joint) and joint shear stress. The performance of the specimens was measured in terms of lateral load-drift response, energy dissipation, mode of failure and stress distribution. Moreover, the effect of concrete damage due to earthquake loading on the performance of beam-column joints under service loading was investigated and a modified damage index was proposed to quantify the magnitude of damage in GFRP-RC beam-column joints under dynamic loading. Test results indicated that the geometrical configuration significantly affects the level of concrete damage and energy dissipation. Moreover, the level of residual damage in GFRP-RC beam-column joints after undergoing lateral displacements was related to reinforcement ratio of the main beams.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.167-176
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• 2017

The purpose of this study was to examine the effect of subordinates' emotional labor on job burnout and job engagement, and verify whether job crafting moderates the relationships between emotional labor and job related attitudes. A total of 301 employees working at various companies in Korea participated in an on-line survey and the data were examined by statistical analysis. The results showed that surface acting positively affected job burnout. It was found that deep acting positively affected job engagement, while negatively affecting job burnout. The results also demonstrated that job crafting moderated the relationship between surface acting and job engagement. It is suggested that employees' proactive behaviors designed to relieve the stress of work can mitigate the negative effect of emotional behavior. On the basis of the results, the implications and future research directions were discussed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.3
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• pp.45-54
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• 2017

With rapid urbanization and reckless urban development in the 21st century, the urban environment has gradually gotten worse, and urban heat island effect has been dramatically intensified. Thus, the importance of street greenery that can mitigate the urban heat island effect has further been highlighted. In this regard, this study was aimed at selecting suitable plant species for street greenery to reduce the urban heat island effect. Towards this end, five roads located in Seocho-gu, Seoul were selected as study sites, and plant species composition and difference of surface temperature were compared and analyzed in relation to the light transmittance. The street with the greatest temperature difference is Bangbae-ro(Platanus occidentalis). On the other hand, the road with the lowest temperature difference is Nambusunhwan-doro(Metasequoia Glyptostroboides). The effect of temperature reduction was found to be associated with light transmittance.Bangbae-ro(Platanus occidentalis) with the lowest light transmittance showed the highest temperature difference and Nambusunhwan-doro(Metasequoia Glyptostroboides) with the highest light transmittance showed the lowest temperature difference. It is analyzed that there are most differences in temperature when the amount of lights coming in between the crown is small. The temperature reduction effect can be obtained by planting deciduous broad-leaved trees. Also species with dense crown and broad width of crown will be able to maximize the effect of temperature reduction. In future studies, it will be necessary to expand the other species of trees in the street, and analyze the germicidal trees and shrubs as well as the differences in the packaging materials.

• The Journal of the Korea Contents Association
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• v.15 no.7
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• pp.531-543
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• 2015

Benjamin, Lusht, and Shilling(1998) suggested that the level of deposit can be used as a tool to resolve the problem of adverse selection by the leaseholder under the circumstance of information asymmetry. In this respect, this research aims to verify how the level of deposit and monthly rent mitigate the problem of information asymmetry existing in the office market in Seoul. So far, the analysis of the office market in Seoul has been difficult due to the fixed rate of deposit and monthly rent. This research attempts to adopt the concept of occupancy cost, a global standard indicator that would replace the default risk of monthly payment for analyzing the market. As a result of a series of empirical analysis, the lessors tend to add about 9 percent of risk premium to the occupancy cost to hedge against the default risk of monthly payment. It allows for estimating at what extent one should reflect the leaseholder's default risk of monthly payment for operating deposit and monthly rent in the office building lease market.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.190-205
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• 2015

In this paper, the impact damage behavior of USN-150B carbon/epoxy composite laminates subjected to high velocity impact was studied experimentally and numerically. Square composite laminates stacked with $[45/0/-45/90]_{ns}$ quasi-symmetric and $[0/90]_{ns}$ cross-ply stacking sequences and a conical shape projectile with steel core, copper skin and lead filler were considered. First high-velocity impact tests were conducted under various test conditions. Three tests were repeated under the same impact condition. Projectile velocity before and after penetration were measured by infrared ray sensors and magnetic sensors. High-speed camera shots and C-Scan images were also taken to measure the projectile velocities and to obtain the information on the damage shapes of the projectile and the laminate specimens. Next, the numerical simulation was performed using explicit finite element code LS-DYNA. Both the projectile and the composite laminate were modeled using three-dimensional solid elements. Residual velocity history of the impact projectile and the failure shape and extents of the laminates were predicted and systematically examined. The results of this study can provide the understanding on the penetration process of laminated composites during ballistic impact, as well as the damage amount and modes. These were thought to be utilized to predict the decrease of mechanical properties and also to help mitigate impact damage of composite structures.

• Journal of Korea Water Resources Association
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• v.50 no.1
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• pp.1-15
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• 2017

Information on radar rainfall with high spatio-temporal resolution over large areas has been used to mitigate climate-related disasters such as flash floods. On the other hand, a well-known problem associated with the radar rainfall using the Marshall-Palmer relationship is the underestimation. In this study, we develop a new bias correction scheme based on the quantile regression method. This study employed a bivariate copula function method for the joint simulation between radar and ground gauge rainfall data to better characterize the error distribution. The proposed quantile regression based bias corrected rainfall showed a good agreement with that of observed. Moreover, the results of our case studies suggest that the copula function approach was useful to functionalize the error distribution of radar rainfall in an effective way.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.1
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• pp.70-79
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• 2017

This study proposes a method to quickly and accurately acquire distance information on direction signs. The proposed method is composed of the recognition of the sign, pre-processing to facilitate the acquisition of the road sign distance, and the acquisition of the distance data. The road sign recognition uses color detection including gamma correction in order to mitigate various noise issues. In order to facilitate the acquisition of distance data, this study applied tilt correction using linear factors, and resolution correction using Fourier transform. To acquire the distance data, morphological operation was used to highlight the area, along with labeling and template matching. By acquiring the distance information on the direction sign through such a processes, the proposed system can be output the distance remaining to the next junction. As a result, when the proposed method is applied to system it can process the data in real-time using the fast calculation speed, average speed was shown to be 0.46 second per frame, with accuracy of 0.65 in similarity value.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1410-1413
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• 2016

Array beamforming for anti-jamming means that jamming signals are superposed destructively, while superposing information signals constructively at a receiver. However, according to channel state variation, the anti-jamming performance of the beamforming can be degraded because of large beamwidth of the sidelobe and lower selectivity of the mainlobe. To mitigate this problem, we introduce a beamformed decoy signal which uses frequency band distinguished from the information signal to make the jammer concentrate its jamming power to a wrong target under limited feedback. In this paper, we show that the performance of the proposed scheme can approach that of optimal one with perfect feedback.