• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.4
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• pp.305-312
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• 2014

This paper discusses real-time peak shaving algorithms for a large-scale battery energy storage system (BESS). Although several transmission and distribution functions could be implemented for diverse purposes in BESS applications, this paper focuses on a real-time peak shaving algorithm for an energy time shift, considering wind power generation. In a high wind penetration environment, the effective load levels obtained by subtracting the wind generation from the load time series at each long-term cycle time unit are needed for efficient peak shaving. However, errors can exist in the forecast load and wind generation levels, and the real-time peak shaving operation might require a method for wind generation that includes comparatively large forecasting errors. To effectively deal with the errors of wind generation forecasting, this paper proposes a real-time peak shaving algorithm for threshold value-based peak shaving that considers fuzzy wind power generation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.4
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• pp.403-407
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• 2023

In this paper, in order to investigate the efficiency of solar power generation system operation, we have studied operation cases such as generation amount, utilization rate, and generation time, and the following conclusions were obtained. The amount of power generation in 2017 was 1,311.48 MWh, and the amount of power generation in 2018 was 1,226.03 MWh. In 2021, 1,184.28 MWh was generated, and 90.30% compared to 2017, and the amount of power generation decreased by 1.94% every year. The deterioration of photovoltaic modules could be seen as one cause of the decrease in power generation. 1,977.74 MWh was generated in the spring, and 1,621.77 MWh was generated in the summer. In addition, 1,478.87 MWh was generated in the fall, and 1,110.55 MWh was generated in the winter, showing a lot of power generation in the order of spring, summer, fall, and winter. From 2017 to 2022, the seasonal utilization rate, daily power generation time, and daily power generation were investigated, and it could be seen that the spring utilization rate varies from 19.29% to 16.99%. It could be seen that the daily generation time in winter decreased from 2.67 hours to 2.13 hours, and in spring it generated longer than spring from 4.63 hours to 4.08 hours. In addition, the daily power generation in winter also decreased from 2.67 MWh to 2.13 MWh, and in spring it decreased from 4.63 MWh to 4.08 MWh, but it could be seen that it is more than in winter.

• Journal of Family Resource Management and Policy Review
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• v.25 no.4
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• pp.71-86
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• 2021

The purpose of this study is to identify the influencing factors of married men's household labor time by generation to understand the changes in male participation in household labor. To this end, married men were classified into Baby Boomers, Generation X, and Generation Y, and the factors of participation in household labor for each generation were analyzed by applying the hypothesis of participation in household labor. As for the data, the original data of the National Statistical Office's "2019 Time Use Survey" were used. Multinomial logistic analysis was conducted to analyze the factors affecting married men's household labor time. As a result of the analysis, household labor time for Baby Boomers can be explained by the hypothesis of economic efficiency, gender role attitude, and the demand/response capability, while household labor time for Generation X can be explained by economic efficiency hypothesis, gender role attitude hypothesis, time-availability hypothesis, and demand/response capability hypothesis. It was found that the household labor time for Generation Y can be explained by the time-availability hypothesis and demand/response capability hypothesis. The fact that each generation has different factors of participation in household labor suggests that the characteristics of each generation should be considered in establishing policies to support the work and family balance for men.

• Korean Journal of Computational Design and Engineering
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• v.13 no.6
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• pp.450-458
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• 2008

Recently, Cartesian grid approach has been popular to generate grid meshes for complex geometries in CFD (Computational Fluid Dynamics) because it is based on the non-body-fitted technique. This paper presents a method of an octree generation and boundary cell clipping using section curves for fast octree generation and elimination of redundant intersections between boundary cells and triangles from 3D triangular mesh. The proposed octree generation method uses 2D Scan-Converting line algorithm, and the clipping is done by parameterization of vertices from section curves. Experimental results provide octree generation time as well as Cut-cell clipping time of several models. The result shows that the proposed octree generation is fast and has linear relationship between grid generation time and the number of cut-cells.

• International Journal of Human Ecology
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• v.16 no.2
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• pp.45-61
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• 2015

This study examines the effects of time spent with parents and peers on generational differences in children's externalizing behavior problems in immigrant families. Using the Child Development Supplement and Time Diaries from the Panel Study of Income Dynamics, we found that first and second generation children exhibited fewer externalizing behavior problems than did third generation children, despite their lower socioeconomic status. First and second generation children spent more time with either one or both parents, and less time with peers, on the weekend day than did third generation children. We found a marginal but beneficial effect of time spent with fathers on the weekday, but not on the weekend day. The implications are that time spent with fathers on weekdays differs from time spent with fathers on the weekend, and that promoting immigrant father involvement on the weekday through school or community programs could benefit immigrant children.

• Journal of Welding and Joining
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• v.21 no.1
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• pp.48-53
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• 2003

The object of this study is to examine the effect of short circuit time ratio (SCTR) and current rise delay time (Td) on the spatter generation at low and medium current range in $CO_2$ welding. The spatter was evaluated by the weight generated in the welding of bead-on-plate for 30 seconds (3 times). Td was varied by order of 0, 0.4, 0.8 and 1.2 msec. At each Td, the short circuit time ratio was varied by the output voltage of the welding power source. In the low current range, it was found that the optimum SCTR was 20~25%, and the minimum spatter generation weight was obtained in the case of Td=0.4msec and SCTR=22% even though the remarkable difference was not showed by the application of Td. In the medium current range, it was confirmed that the arc was stable though the SCTR was increased from 20% to 40% by the control of current wave. Spatter generation weight depended on the variation of Td, and the lowest value of spatter generation weight occurred at Td=0.8~1.2msec.

• Journal of Family Resource Management and Policy Review
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• v.27 no.4
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• pp.63-74
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• 2023

This study considered allocating and balancing time use as an important factor that determines the quality of life, and attempted to analyze the happiness of married women through the perspective of satisfaction with time use. We investigated the structure of time use, and analyzed the factors that affect happiness in the perspective of time use through the Time Use Survey data. Analyzing the happiness of married women, we found out that the level of happiness and the factors affecting happiness varied by generation. In the case of economically active women, the happiness of baby boomers and Generation X was mostly impacted by mandatory work hours, while the happiness of Generation Y was mostly impacted by the presence of care-dependent people. However, in the case of economically unactive women, the happiness of baby boomers and Generation X was mostly impacted by leisure and volunteering time that could be used freely, while the happiness of Generation Y was mostly impacted by the attitude toward gender roles. Therefore, through the perspective of time use, the happiness and the factors determining the happiness of married women differs by generation and economic activeness. This study has significant implications for the establishment of family policies for married women.

• Journal of Power Electronics
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• v.14 no.2
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• pp.249-256
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• 2014

A novel topology generation method for the no dead-time three-phase AC/DC converter is proposed in this study. With this method, a series of no dead time topologies are generated and their operation principles are analyzed. The classic three-phase bridge AC/DC converter can realize a bidirectional operation. However, dead-time should be inserted in the driving signals to avoid the shoot-through problem, which would cause additional harmonics. Compared with the bridge topology, the proposed topologies lack the shoot-through problem. Thus, dead time can be avoided. All of the no dead time three-phase AC/DC converters can realize bidirectional operation. The operating principles of the converters are analyzed in detail, and the corresponding control strategies are discussed. Comparisons of waveform distortion and efficiency among the converters are provided. Finally, 9 KW DSP-based principle prototypes are established and tested. Simulation and experimental results verify the theoretical analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1218-1222
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• 2008

We investigate the effect of rise time of a pulse bias voltage on atmospheric plasma generation. With the faster rise time of the pulse bias, the glow discharge appears to be more uniformly generated along the electrodes. I-V measurement confirms that higher loading power can be obtained using the faster rise time. A new understanding for atmospheric plasma generation at a micro-gap electrode is suggested.

• Journal of Electrochemical Science and Technology
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• v.13 no.3
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• pp.323-338
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• 2022

Heat generation and temperature of a battery is usually presented by an equation of current. This means that we need to adopt time domain calculation to obtain thermal characteristics of the battery. To avoid the complicated calculations using time domain, 'state of charge (SOC)' can be used as an independent variable. A SOC based calculation method is elucidated through the comparison between the calculated results and experimental results together. Experiments are carried for rapid resistive discharge of a large-capacitive lithium secondary battery to evaluate variations of cell potential, current and temperature. Calculations are performed based on open-circuit cell potential (SOC,T), internal resistance (SOC,T) and entropy (SOC) with specific heat capacity.