• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.375-377
• /
• 1999

It is necessary to obtain the high performance of the inverter system that control the output current of inverters. The dead time causes detrimental effects to the control performance of the inverter system. So we need to compensate the dead time effects. And the dead time minimization switching method can be considered as the best way to avoid the dead time effects fundamentally. In this paper, a new dead time minimization switching strategy is proposed. According to the proposed method, very short dead time is adopted in only once when the current polarity is changing. And the adopted dead time is equal to the applied dead time or shorter than it. As the proposed method can be done with the porlarity information of the reference current. it is easy to avoid some problems in comparison with the case that the real current is used to get the polarity changing time; level detection difficulty, noise problem and so on.

• Human Ecology Research
• /
• v.53 no.1
• /
• pp.1-16
• /
• 2015

This study aims to examine the effects of high school students' time management behaviors on their satisfaction with educational consumption and school life. Three hundred seventy-six high school students in Seoul participated in this investigation. The SPSS ver. 19.0 program was adopted for the descriptive analysis, factor analysis, Cronbach's ${\alpha}$, and multiple regression analysis. The results of the present study can be summarized as follows: first, the levels of time management behavior, satisfaction with educational consumption at school, and satisfaction with school life were relatively high. Second, an analysis of the relative influence on satisfaction with educational consumption revealed that the students' time management behavior was the most influential factor, followed by academic achievement. As the levels of time management behavior and academic achievement were high, the level of satisfaction with educational consumption was high. Finally, an analysis of the relative influence of satisfaction with school life also revealed that the students' time management behavior was the most influential factor, followed by academic achievement. Based on the findings, that is, the effects of high school students' time management behavior and other involved variables on their satisfaction with educational consumption and school life, a future study can present specific ways to enhance the level of satisfaction with educational consumption and school life.

• Journal of Haehwa Medicine
• /
• v.16 no.2
• /
• pp.303-310
• /
• 2007

The purpose of this study is to investigate the anti-coagulant effects of Polygoni Mutiflori Radix extracts. The results were as follows : 1. This study show that Polygoni Mutiflori Radix extracts have Anti-coagulant significant effects on Prothrombin time in vitro test. 2. This study show that Polygoni Mutiflori Radix extracts have Anti-coagulant significant effects on Activated Partial Thromboplastin Time vitro test.

• Korean Journal of Child Studies
• /
• v.31 no.6
• /
• pp.1-13
• /
• 2010

This study examined the time-dependent effects of changes in private education on the trajectories of academic achievement among early adolescents. Five-wave data was employed from the KYPS; the participants being 2844 (1524 boys, 1320 girls). All were 4th graders in 2004 and became 8th graders in 2008. Latent growth curve model indicated that academic achievement significantly decreased over the five time points, but there were significant individual differences as well. Participants who reported higher initial levels of academic achievement tended to decrease in academic achievement more slowly over time compared to participants who reported lower levels of initial academic achievement. The effects of private education on academic achievement were at their most powerful when participants were in the 4th grade. Private educational experiences among 6th graders had relatively less influence upon the academic achievement of 7th graders.

• Safety and Health at Work
• /
• v.14 no.1
• /
• pp.100-106
• /
• 2023

Background: Our study aimed to investigate the mediating role of work-family conflict (WFC) on the relationship between long commutes and workers' anxiety and insomnia. Methods: Our study measured the two dimensions of WFC, time-related, and strain-related, which were considered multiple mediators. The mediating effect of WFC on anxiety and insomnia was investigated by decomposing the total effect into a direct effect (long commuting time → anxiety or insomnia) and an indirect effect (long commuting time → WFC → anxiety or insomnia). The combined indirect effect (joint indirect effect) of strain-related WFC and time-related WFC was estimated. The effects were presented as odds ratios and 95% confidence intervals (CIs). Results: The direct effect of 120 min or longer of commuting time was 1.39 (95% CI: 1.17-1.65) times increase in the odds of anxiety and 1.64 (95% CI: 1.41-1.90) times increase in the odds of insomnia than those whose commuting time was less than 60 min. In the case of indirect effects, those whose commuting time was 120 min or longer had 1.13 times higher odds of anxiety (95% CI: 1.07-1.18) and 1.12 times higher odds of insomnia (95% CI: 1.07-1.17) via WFC. The joint indirect effects accounted for 26.4% and 18.5% of the total effect on anxiety and insomnia, respectively. The longer the commuting time, the stronger both direct and indirect effects. Conclusions: Our findings highlight the mediating effect of WFC on the relationship between long commuting times and workers' anxiety and insomnia.

• Korean Journal of Child Studies
• /
• v.35 no.1
• /
• pp.119-133
• /
• 2014

The purpose of this study is to examine the effects of time perspective, self-control and cellular phone addiction on academic procrastination, and to cellular phone addiction has any mediating effects in relation to the effects of adolescents' time perspective and self-control on academic procrastination. For this study, a survey was conducted with total 651 students in middle and high schools. Those who omitted responses or answered in ways which were otherwise invalid were excluded and finally, questionnaires responded to by 558 students were analyzed. Employing SPSS Win 12.0, average value, standard deviation, frequency analysis, Pearson's correlation analysis, stepwise multiple regression analysis, and simple linear regression analysis were used for the purposes of statistical analysis. In conclusion, first, explanations were made in order of future-oriented time perspective which is subordinate domain of view of time perspective, self-control, and cellular phone addiction. Second, it was found that cellular phone addiction has partially mediating effect on the relationships between future-oriented time perspective which is a subordinate area of adolescents' time perspective, and academic procrastination. Third, it was found that cellular phone addiction has partially mediating effect on the relationships between adolescents' self-control and academic procrastination.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.468-471
• /
• 1997

In this paper, we investigate the time-sampling effects on the digital implementation of singular perturbation based STT autopilot with excellent performance and propose a compensation method for the time-sampling effects. In digitization of analog STT autopilot, it is found that the stability margin of the fast dynamics is mostly affected to lead to rapid decrease. Under the this analysis, a composite digital controller with additional compensator for fast dynamics is proposed to improve the time-sampling effect and a simulation verifies the result.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.2
• /
• pp.322-329
• /
• 1995

Series of experimental work was performed to mold tensile specimens by using the injection molding machine Mold temperature, melt temperature and packing time were chosen as processing parameters for studying the effects of those conditions on the linear shrinkage of final product. Here, each processing variable was decided from the numerical simulation and resin manufacturer's suggested value. The effects of molding conditions on the linear shrinkage in flow direction of the resin were analyzed by measuring the parts 2, 10, 30 and 60 days after molding. As a result, the linear shrinkage increased with the higher mold and melt temperature, and the change of mold temperature has shown more influence. The linear shrinkage of polypropylene has been found to progress up to 30 day with the lapse of the time, and the amount of the linear shrinkage has shown to be between 2.14% and 2.75%. In addition, the effects of packing pressure on the weight has shown to be extremely significant up to freezing time, and proper packing time of the tensile specimen has been found to be 2.0 seconds.

• Herbal Formula Science
• /
• v.11 no.1
• /
• pp.161-170
• /
• 2003

This study was designed to elucidate the analgesic effects of Jakyakgamchotang and Radix paeinia, Radix Glycyrrhiziae which are the component of Jakyakgamchotang in mice. The analgesic effects were measured by the Whittle's method and hot plate method. The results were as follows ; After the administration of Jakyakgamchotang extrace, the frequency of writhing syndrome was significantly inhibited. After the administration of Radix paeinia extract, the frequency of writhing syndrome was significantly inhibited. After the administration of Radix Glycyrrhiziae extract, the frequency of writhing syndrome was significantly inhibited. After the administration of Jakyakgamchotang extrace, paw licking time and escape time were significantly prolonged. After the administration of Radix paeinia extract, paw licking time was significantly prolonged. After the administration of Radix Glycyrrhiziae extract, paw licking time was significantly prolonged. It is concluded that the analgesic effects of Jakyakgamchotang were found to be more effective than Radix paeinia and Radix Glycyrrhiziae.

• Journal of the Society of Naval Architects of Korea
• /
• v.47 no.2
• /
• pp.242-247
• /
• 2010

To consider effects of essential parameters of water impact pressure on dynamic structural responses of bow bottom structures, a parametric study for a ship bottom panel is carried out. The idealized pressure time history models were assumed by triangular and rectangular shapes in time domain. The main loading parameters are duration time and peak pressure value maintaining the same impulse value. The structural models for local bottom stiffened panels of a container ship are analysed. The natural frequency analysis and transient dynamic response analysis are performed using MSC/NASTRAN. Added mass effects of contacting water are considered and the pressure distributions are assumed to be uniform in the whole water contacting surface. The effects of loading parameters on the structural responses, especially maximum displacements, are considered. Besides the peak pressure value, effects of duration time correlated with natural frequencies are thought to be the important parameters.