• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.3
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• pp.20-28
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• 2015

Performance parameters of solid rocket motor with multi axis pintle nozzles were analyzed theoretically and modeled. For figuring out the governed variable of dynamic characteristics of system, dynamic analysis was done by using established model. To present characteristics of this system, the model should include not only internal ballistics of propulsion unit but also actuating system to move pintle. For solid rocket motor with multi axis pintle nozzles, not only performance of steady state but also dynamic characteristic of transient state is important design parameter to precise thrust control. Therefore, response time of open-loop system was analyzed by using established model and requirement about response time was satisfied by controlling pressure.

• Clinical and Experimental Reproductive Medicine
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• v.48 no.4
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• pp.374-379
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• 2021

Objective: We aimed to evaluate associations between the ratio of serum estrone (E1) to estradiol (E2) and parameters related to serum glucose metabolism and insulin resistance in women with polycystic ovary syndrome (PCOS). Methods: In total, 133 women between the ages of 18 and 35 diagnosed with PCOS were enrolled in this study. All participants with PCOS underwent blood tests to determine hormonal and biochemical metabolic parameters and a standard 2-hour 75-g oral glucose tolerance test. They were divided into two groups according to the serum E1-to-E2 ratio: group 1 (E1/E2 ratio <2.0) and group 2 (E1/E2 ratio ≥2.0). Results: In the comparative analysis, the waist-to-hip ratio (WHR) was the only clinical variable that was significantly different between the two groups. Patients with a higher E1/E2 ratio showed higher fasting insulin levels, homeostasis model for insulin resistance, and postprandial glucose level at 2 hours (PPG2). In a correlation analysis, only PPG2 was significantly related to the serum E1/E2 ratio. However, after controlling for the confounding effects of body mass index (BMI) and WHR, fasting glucose was also significantly correlated with the serum E1/E2 ratio. Conclusion: Women with PCOS with a higher serum E1/E2 ratio were found to be more likely to show higher fasting insulin and postprandial glucose levels. Significant correlations were found between the serum E1/E2 ratio and both fasting and postprandial serum glucose levels after adjusting for BMI and WHR in women with PCOS.

• Journal of Preventive Medicine and Public Health
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• v.51 no.6
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• pp.320-325
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• 2018

Objectives: This pilot study tested the effectiveness of a brief alcohol-related intervention delivered by the social media app WeChat to teach about ethanol-induced facial flushing and increase the willingness of students who see another student flushing to suggest that he or she should reduce or stop drinking. In the context of Chinese drinking culture, it is sometimes socially difficult to refuse a drink, even when experiencing physical discomfort, such as flushing. Methods: Classrooms of students in a medical university in China were randomly assigned to the intervention or control group. Students in the intervention group were invited to view 3 alcohol education lessons on WeChat during a 2-week period. A pretest and posttest before and after the 2-week period assessed changes in students' willingness to intervene if they saw someone flush while drinking. Data were collected about students' alcohol use and their ratings of the lessons. Results: Mixed-design analysis of variance yielded a significant time-by-treatment interaction effect on the variable of willingness to suggest that a flushing person stop or slow down their drinking, and the change was significant between the intervention and control groups. One-way analysis of covariance yielded a significant treatment effect at the posttest, after controlling for the pretest score. Students rated the lessons above the midpoint of the scale for being informative, interesting, and useful. Conclusions: The pilot study showed that a brief alcohol-related intervention delivered by WeChat could produce a measurable positive change in the willingness of university students to suggest that a student who flushes should stop drinking. This pilot study also suggested improvements for future lessons and evaluation design.

• Asia-Pacific Journal of Business
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• v.11 no.4
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• pp.205-224
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• 2020

Purpose - This study aimed to identify the effects of ownership structures on agency costs in internationally diversified firms listed on the KOSDAQ market. Design/methodology/approach - A total of 5,824 samples were finally selected and empirically analyzed for a total of nine years from 2011 to 2019, during which the International Accounting Standards had been mandatory for firms listed on the KOSDAQ market. Findings - The results of this study showed that the effects of ownership structures on the ratio of asset turnover are positive for the major share and foreign equity ratios of international diversified firms. Moreover, by selecting the ratio of entertainment expenses as a proxy for agency expenses, this study confirmed that the effects of the ownership structure of an international diversified entity on entertainment expenditure were determined to show a significantly negative relation to entertainment expenditure, thus indicating that the higher the ratio of major shareholders, the more appropriately control the expenditure of entertainment expenses through arbitrary private deviations of the management.Furthermore, considering the effect of the ownership structure on the expenditure of sales and administrative expenses as a proxy variable for agency costs, this study verified that the majority share ratio of international diversified firms was negative to the expenditure of sales and administrative expenses, confirming that the higher the share of major shareholders, the lower the selling and administrative costs, but insignificant.Finally, as a result of determining whether the ownership structure of an international diversified firm affects the holding of free cash, the majority share of this firm shows a significantly negative relation to the ratio of the holding of surplus cash, indicating that the higher the proportion of major shareholders, the more appropriately control the holding of the entity's free cash through arbitrary private deviance by the manager. Research implications or Originality - Major shareholders of an internationally diversified firm listed on the KOSDAQ market play a positive role in the firm's performance by properly controlling agency costs that may be incurred by the management.

• Journal of Family Relations
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• v.23 no.2
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• pp.133-155
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• 2018

Objectives: This study examined the differences in the intention of having a second child and the related factors among Chinese and Vietnamese migrant women from the perspective of adaptation theory. Methods: Data were drawn from the National Survey on Multi-Cultural Families in 2009 and 2015. Among the total 7,615 married migrant women (Korean-Chinese, Chinese-Han, Vietnamese), those within the age group 20-39 within the first 5 years of marriage who had one child were selected. A frequency analysis, chi-squared test, and logit regression analysis were performed. Results: Different ethnic groups had different reasons for having a second child and the related factors also differed between 2009 and 2015. In 2009, after controlling the related variables, the intention of Korean-Chinese and Chinese-Han married immigrant women to have a second child was higher than that of Vietnamese women, but no such difference was found in 2015. Participation in their local community, first marriage, the gender of the first child, and whether they were living with their parents-in-law were associated with the intention of migrant women having a second child in the 2009 analysis model but these factors were not significant in the 2015 analysis model. In the latter model, the household income, a variable related to economic conditions, has a positive effect on the intention of having a second child. Conclusions: The significance of this study supports adaptation theory by addressing the similarity in the childbirth intention between recently married immigrant women and Korean women.

• Asia-Pacific Journal of Business
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• v.10 no.3
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• pp.69-93
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• 2019

There is a growing interest in researching new leadership and efficient organizational management due to the changes and spread of Information Communications Technologies (ICT) related organizations. Therefore, the purpose of this study is to examine the effect of leadership on organization in ICT R & D, and to follow the relationship between coaching leadership, leader member exchange (LMX), emotional intelligence of leaders, and organizational effectiveness. In order to verify this research problem, a total of 310 people were surveyed from employees working in the ICT R & D field. Reliability analysis of the measuring tool was tested on 80 pilot surveys in advance, and the final 285 data were used for empirical analysis excluding 25 unsatisfactory responses. For analysis, SPSS 22.0 program and AMOS were used to analyze the reliability, validity, path analysis, and control effects of the measurement tools. The findings demonstrate empirically the positive relationship between LMX and organizational effectiveness on coaching leadership in ICT R & D. In addition, by empirically verifying the effect that the emotional intelligence of the leader regulates the relationship between LMX, organizational effectiveness, and coaching leadership, then emotional intelligence of the leader can be usefully applied in ICT R & D. Furthermore, the demand for more in-depth research on coaching leadership, LMX, and emotional intelligence of leaders, which positively affects organizational effectiveness, was identified as demand for ICT R & D is increasing and horizontal and interactive leadership is needed.

• Journal of Sensor Science and Technology
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• v.30 no.2
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• pp.114-118
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• 2021

In this study, the sensitivity of an active pixel sensor (APS) was adjusted by employing a gate/body-tied (GBT) p-channel metal-oxide semiconductor field-effect transistor (PMOSFET)-type photodetector with a transfer gate. A GBT PMOSFET-type photodetector can amplify the photocurrent generated by light. Consequently, APSs that incorporate GBT PMOSFET-type photodetectors are more sensitive than those APSs that are based on p-n junctions. In this study, a transfer gate was added to the conventional GBT PMOSFET-type photodetector. Such a photodetector can adjust the sensitivity of the APS by controlling the amount of charge transmitted from the drain to the floating diffusion node according to the voltage of the transfer gate. The results obtained from conducted simulations and measurements corroborate that, the sensitivity of an APS, which incorporates a GBT PMOSFET-type photodetector with a built-in transfer gate, can be adjusted according to the voltage of the transfer gate. Furthermore, the chip was fabricated by employing the standard 0.35 ㎛ complementary metal-oxide semiconductor (CMOS) technology, and the variable sensitivity of the APS was thereby experimentally verified.

• The Journal of the Korea Contents Association
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• v.22 no.1
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• pp.545-556
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• 2022

This study aims to ensure that the help of family members and caregivers has a controlling effect in the process of restrictions on the Activities of Daily Living affecting depression in the elderly. Based on the 15th data of the Korea Welfare Panel, technical statistics, average difference analysis, correlation analysis, regression analysis, and control effect analysis were conducted on 4,214 senior citizens aged 65 or older. The results of the study are as follows. First, restrictions on the Activities of Daily Living has been shown to have a significant effect on depression in older people. Second, between restrictions on the Activities of Daily Living and depression of the elderly, the family's private help has been shown to function as a modulator to alleviate depression of the elderly. Third, between restrictions on the Activities of Daily Living and depression of the elderly, public help from caregivers does not function as an adjustment variable that alleviates depression of the elderly. Implications were derived and policy suggestions were presented based on these results.

• Journal of Korea Trade
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• v.24 no.1
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• pp.1-34
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• 2020

Purpose - In this study, we investigate determinants of hedging with derivatives and its effect on firm value and firm risk for Korean firms. Design/methodology - To avoid the endogeneity problem pointed out in previous studies, we use a two-stage analysis by using gains and losses from derivatives as instrument variable for hedging with derivatives. Findings - Our analysis on the determinants of hedging shows that firms that are more leveraged and less profitable, and with more growth opportunities are likely to hedge through derivatives. Additionally, large firms, firms less diversified into industry, and firms more diversified geographically are likely to use derivatives. Our two-stage analysis shows that indicators of hedging with derivatives have an insignificant effect on firm value, and the indicator of futures/forwards use and of swaps use have significant negative effect on firm value. Whereas, the extent of hedging with derivatives has positive effect on firm value for all types of foreign currency derivatives, which suggests that moderately low hedgers use derivatives inefficiently, but extensive hedgers use derivatives properly. With regard to firm risk, hedging with derivatives increases market-based risk, but decreases accounting-based risk. Thus, we conclude that Korean firms use derivatives to manage operational volatility rather than to manage market risk, and accounting-based risk reduction through hedging is not directly translated into higher firm value. Originality/value - This is not the first study to investigate hedging behavior of Korean firms, but the sample period that that this study analyzed is the longest and various method are used to control the endogeneity problem. We investigate not only total foreign currency derivatives but also by types of derivatives, including futures/forwards, options, and swaps.

• Journal of the Korean Society for Library and Information Science
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• v.57 no.1
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• pp.45-68
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• 2023

The purpose of this study is to longitudinally analyze impact factors on library use. One of library use indicators, the number of circulated books was statistically analyzed with latent growth model and growth mixture model. Library data from 2014 to 2019 were collected from the National Library Statistics System, and 846 public libraries were analyzed. As results, the number of circulated books were decreased, but it was tempered. Next, with controlling the factor affecting the dependent variable, the size of collection and the number of participants in reading programs provided by public libraries were statistically significant. Lastly, 5 classes were identified by applying the growth mixture model, and the number of librarians was significantly associated with trajectory class membership.