• Journal of Power Electronics
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• 제13권6호
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• pp.928-938
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• 2013

This paper proposes a novel control method for a multi-output switched-resonant converter. Output voltage can be regulated against variations in the supply voltage and load by controlling the voltage of the resonant capacitor (pulse amplitude control). Precise control is possible when pulse amplitude control is combined with pulse number control. The converter is analyzed, and design considerations are explained by using examples. Control implementation is described and load regulation and ripples are analyzed by simulation and hardware results. The topology is modified to obtain an additional negative output without any additional hardware other than a diode. The analysis of such a triple output converter with two positive outputs and one negative output is conducted and confirmed. The topology and control scheme are scalable to any number of outputs.

• Bulletin of the Korean Mathematical Society
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• 제34권2호
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• pp.211-223
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• 1997

Lehmann [13] introduced the concept of positive(negative) dependence together with some other dependence concepts. Since then, a great numerous multivariate inequalities have been obtained. For a references of available results, see Karlin and Rinott [12], Ebrahimi and Ghosh [8] and Sampson [14]. Whereas a number of dependence notions exist for multivariate processes (see Friday [10]), recently, Ebrahimi [7] introduced some new dependence concepts of the hitting times of stochastic processes.

• Bulletin of the Korean Mathematical Society
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• 제45권2호
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• pp.277-283
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• 2008

The paper deals with the values at the negative integers of a certain Dirichlet series related to the Riemann zeta function and with the expression of these values in terms of Bernoulli numbers.

• Journal of Electrical Engineering and Technology
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• 제1권4호
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• pp.423-426
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• 2006

Distance relays achieve selective tripping by measurement of all short circuit fault conditions inside set reaches. The direction of the fault, forward or reverse is commonly determined with a dedicated measurement to ensure selectivity under all conditions. For the direction decision (measurement) a number of alternatives are available. This paper describes a loop selective direction measurement and illustrates by means of a typical fault why this is superior to a non loop selective direction measurement such as that based on negative sequence quantities.

• Journal of Families and Better Life
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• 제35권1호
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• pp.31-44
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• 2017

The purpose of this study was to examine the relationship between toddler's negative emotionality, parenting behavior, and the moderating roles of mother's personality. The participants in this study consisted of 221 mothers of toddlers (aged from 18 to 35months) in Seoul. The participants completed questionnaires on toddler's negative emotionality, their personality and parenting behavior. The collected data were mainly analyzed by descriptive statistics, t-test, one-way ANOVA, Duncan test, Pearson's correlation and the multiple regression analysis. The main findings of this study were as follows. First, there was a significant difference in the negative parenting behavior according to the mother's educational level. Second, relations between individual variables and parenting behavior were analyzed. As a result, number of children, mother's age, toddler's negative emotionality, and mother's personality were significantly correlated with parenting behavior. Third, through the analysis of the moderating effect of the mother's personality on the relationship between the toddler's negative emotionality and parenting behavior, it was found that interactions between the mother's neuroticism and the toddlers' negative emotionality affected the mother's warm parenting behavior. And interactions between the mother's extraversion and the toddlers's negative emotionality affected the mother's rejection parenting behavior. The results of this study provide basic data to support mothers' positive parenting behavior.

• Journal of dental hygiene science
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• 제24권1호
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• pp.22-28
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• 2024

Background: Particulate matter (PM) has been extensively observed due to its negative association with human health. Previous research revealed the possible negative effect of air pollutant exposure on oral health. However, the predictive model between air pollutant exposure and the prevalence of periodontitis has not been observed yet. Therefore, this study aims to propose a predictive model for the number of patients with periodontitis exposed to PM and atmospheric factors in South Korea using deep learning. Methods: This study is a retrospective cohort study utilizing secondary data from the Korean Statistical Information Service and the Health Insurance Review and Assessment database for air pollution and the number of patients with periodontitis, respectively. Data from 2015 to 2022 were collected and consolidated every month, organized by region. Following data matching and management, the deep neural networks (DNN) model was applied, and the mean absolute percentage error (MAPE) value was calculated to ensure the accuracy of the model. Results: As we evaluated the DNN model with MAPE, the multivariate model of air pollution including exposure to PM_2.5, PM₁₀, and other atmospheric factors predict approximately 85% of the number of patients with periodontitis. The MAPE value ranged from 12.85 to 17.10 (mean±standard deviation=14.12±1.30), indicating a commendable level of accuracy. Conclusion: In this study, the predictive model for the number of patients with periodontitis is developed based on air pollution, including exposure to PM_2.5, PM₁₀, and other atmospheric factors. Additionally, various relevant factors are incorporated into the developed predictive model to elucidate specific causal relationships. It is anticipated that future research will lead to the development of a more accurate model for predicting the number of patients with periodontitis.

• Journal of Environmental Health Sciences
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• 제33권2호
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• pp.104-114
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• 2007

This study evaluated the airborne concentrations of bacteria, Gram-negative bacteria, and fungi in waiting rooms, wards, and outdoors, according to time and particle size between October 17 and November 28, 2003. The geometric mean number of airborne bacteria was highest in the morning. The more people there were, the higher was the total bacteria concentration. The concentration of fungi was also highest in the morning. Temperature and relative humidity affected the concentrations of fungi significantly (p<0.05). This study found relationships between microorganism concentrations and (actors such as time, place, temperature, humidity, ventilation, and number of people. Therefore, to manage the pollution resulting from airborne microorganisms, each time, place, and environmental factor should be examined periodically, and the number, size, and movement of airborne microorganisms should be evaluated.

• Journal of Information Technology Services
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• 제14권2호
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• pp.177-193
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• 2015

A great number of customers, who want to watch movies usually check out online reviews before choosing what to watch a movie. The most representative online media that customers consult are portal sites and SNS (Social Network Service). Although there have been numerous studies on online eWOM (e-Word of Mouth) and the effects of online media in businesses, it remains a question that which media is best for WOM (Word of Mouth) when selecting movies. This research examines customer's intention for consulting eWOM and for watching movies according to the number and tendency of online replies. We have compared portal sites and SNS about information of movie. The study shows that a large number of positive replies can affect the intention for WOM and choosing movies. Facebook has more influence than portal sites when choosing what to watch when replies consist of large and positive comments. However, there is no difference between the two types of media when they consist of negative comments.

• Journal of Korea Multimedia Society
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• 제23권1호
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• pp.93-101
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• 2020

Korea, as a leader of Internet and game sector in IT industry, has been playing an important role in increasing its industrial development. This country has won the first place in wireless broadband usage and contributed to Internet game industry development. This means that Korean use smartphones most. It is juveniles that use Internet and smartphones most among Korean who use teenage., the number of the teenagers who overuse smartphones or Internet has surpassed 200,000. The number of the adolescents who spend more time using smartphone and Internet is about 180,000 and the number of the teens who are over-dependent to smartphone having trouble living their lives is over 22,000. The SNS usage rate of the contents that teens are most likely to use has accounted for over 80 percent. Among teens, SNS is being considered as a major means that builds relationship due to smartphone technology and the prevalence of smartphones. However, the use of SNS among youths has two sides; one is positive, the other negative. Not only does SNS have a positive function that it keeps relationship but it also has a negative function that it can lead to smartphone addiction.

• Journal of the Korean Society of School Health
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• 제21권1호
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• pp.1-9
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• 2008

Purpose : To investigate the degree of apearance satisfaction, self-es teem and school maladjustment and the corelation among the three variables in elementary, middle and high school student. Method : The subject of this study was total 878 students of elementar y, midle, and high schol in Seoul. The data were collected through a sel f-administered questionaire f rom June, 18 to June, 29, 2007. Results : The mean of apearance satisfaction was 29.8. Apearance sati according to school, presence of parents, academic performance, and the number of friend. The mean of self-estem was 77.9. Self-esteem showed significant diferences according to grade, academic performance, and the number of friend. The mean of school maladjustment was 54.3. School maladjustment gender, academic performance, and the number of friend. In the corelation among three variables, there was a positive corelation betwen apearance satisfaction and self-esteem but there was a negative corelation betwen appearance satisfaction and school maladjustment, and also a negative corr multiple linear regresion analysis to investigate influencing factor on schol maladjustment, apearance satisfaction and self-estem were significant variables. Conclusion : We should make regular education program and provide students through school classes which help from their parents.