• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.120-124
• /
• 1995

TCSC can not only increase power flow but also damp low frequency oscillation by controlling firing angles of thyristors. But, a model considering voltage, current firing angles is not derived. This paper used a small signal model considirng these variables which was derived in paper [1]. TCSC model is combined with swing equation. Being related to rotor angles and firing angles of thyristors, current and synchronizing torque coefficient is reformulated. Because firing angles of thyristors can be controlled only twice within one period, swing equation is transformed to discrete time model. It is shown that low frequency oscillation can be damped by controlling firing angles in one machine infinite bus power system.

• Journal of Positioning, Navigation, and Timing
• /
• v.9 no.2
• /
• pp.89-98
• /
• 2020

Prediction of clock behaviors is necessary to generate very high stable system time which is essential for a satellite navigation system. For the purpose, we applied the Auto-Regressive Integrated Moving Average (ARIMA) model to the prediction of two hydrogen masers' behaviors with respect to the rapid Coordinated Universal Time (UTCr). Using the packaged programming language R, we made an analysis and prediction of time series data of [UTCr - clocks]. The maximum variation width of the residuals which were obtained by the difference between the predicted and measured values, was 6.2 ns for 106 days. This variation width was just one-sixth of [UTCr-UTC (KRIS)] published by the BIPM for the same period. Since the two hydrogen masers were found to be strongly correlated, we applied the Vector Auto-Regressive Moving Average (VARMA) model for more accurate prediction. The result showed that the prediction accuarcy was improved by two times for one hydrogen maser.

• The Journal of Asian Finance, Economics and Business
• /
• v.8 no.2
• /
• pp.737-745
• /
• 2021

This study aims to determine whether there are differences in the average abnormal return, trading volume activity, and trading frequency activity in pharmaceutical stocks before and after the announcement of the first case of the coronavirus (COVID-19) in Indonesia. The sample was selected using a purposive sampling method and collected as many as nine pharmaceutical companies listed on the Indonesia Stock Exchange during 2019-2020. The data used in this study were secondary data in the form of daily data on stock closing prices, Composite Stock Price Index (IHSG), stock volume trading, number of shares outstanding, and stock trading frequency. This study was an event study with an observation period of 14 days, namely seven days before and seven days after the announcement of the coronavirus's first positive case in Indonesia. Hypothesis testing employed the paired sample t-test method. Based on the results, it was found that there was no difference in the average abnormal return of pharmaceutical stocks before and after the announcement of the first case of COVID-19. However, there was a difference in the average trading volume activity and the average trading frequency activity in pharmaceutical stocks before and after the announcement of the first case of COVID-19.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.20 no.4
• /
• pp.628-638
• /
• 2014

Purpose: This study identifies the relation among the essentials of fundamental nursing skills performance (EFNSP), work capability and stress from work experienced by new clinical nurses. Method: This is a cross-sectional descriptive study with a self-reported questionnaire. The subjects were 224 new clinical nurses employed by general hospitals having more than 400 beds. The data, collected from February 10 to March 7, 2014, were analyzed using descriptive statistics, t-tests, ANCOVA, Pearson's correlation analysis and hierarchical linear regression. Results: The highest frequency of EFNSP of new clinical nurses was vital sign measurement (4.74, ${\pm}.89$) and the lowest frequency of performance was Basic CPR & defibrillator application (1.81, ${\pm}.94$). There were significant positive correlations between frequency and confidence of EFNSP (r=.64, p<.001), frequency and work capability (r=.34, p<.001), and confidence of EFNSP and work capability (r=.48, p<.001), but negative correlation stress from work and work capability (r=-.17, p=.009). General characteristics, stress from work, frequency and confidence in EFNSP and stress from work explain 25.1% of work capability. Conclusion: This result suggests the importance of EFNSP education in nursing schools and availability of opportunities to practice EFNSP during the post-graduation waiting period until assignment to a hospital.

• Journal of Wetlands Research
• /
• v.17 no.1
• /
• pp.80-90
• /
• 2015

Variability of precipitation pattern and intensity are increasing due to the urbanization and industrialization which induce increasing impervious area and the climate change. Therefore, more severe urban inundation and flood damage will be occurred by localized heavy precipitation event in the future. In this study, we analyze the future frequency based precipitation under climate change based on the regional frequency analysis. The observed precipitation data from 58 stations provided by Korea Meteorological Administration(KMA) are collected and the data period is more than 30 years. Then the frequency based precipitation for the observed data by regional frequency analysis are estimated. In order to remove the bias from the simulated precipitation by RCP scenarios, the quantile mapping method and outlier test are used. The regional frequency analysis using L-moment method(Hosking and Wallis, 1997) is performed and the future frequency based precipitation for 80, 100, and 200 years of return period are estimated. As a result, future frequency based precipitation in South Korea will be increased by 25 to 27 percent. Especially the result for Jeju Island shows that the increasing rate will be higher than other areas. Severe heavy precipitation could be more and more frequently occurred in the future due to the climate change and the runoff characteristics will be also changed by urbanization, industrialization, and climate change. Therefore, we need prepare flood prevention measures for our flood safety in the future.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.5
• /
• pp.341-350
• /
• 2018

A series of model tests was carried out to investigate the vortex-induced vibration (VIV) characteristics of a free hanging PVC pipe under forced oscillation conditions. The prescribed displacement with a period and amplitude was forced at the top of the riser. The motion of the riser along its length was measured with underwater cameras in three dimensions. The top-excited responses in the inline direction and vortex-induced vibration in the cross-flow direction were examined in the time and frequency domains. Multi-peak frequencies in the VIV were demonstrated to be strongly dependent upon the Keulegan-Carpenter number, corresponding with the results of Blevin. It was found that the Reynolds numbers (excitation period) was a critical parameter for the dominant VIV characteristics, even under the condition of using the same Keulegan-Carpenter number, under the top-excited condition. In the resonance at the nth natural frequency by the forced-motion induced VIV frequency, the riser responded with a large amplitude and forced frequency, dominantly in the VIV CF direction.

• Journal of Nutrition and Health
• /
• v.46 no.1
• /
• pp.26-33
• /
• 2013

The purpose of this study was to investigate the sodium intake of office workers using 24-hour urine analysis and to analyze the correlation matrix between variables. The sodium intake of the subjects (n = 137), based on a 24-hr sodium excretion period, was male (n = 56) 6072.4 mg and female (n = 81) 5,168.2 mg. Urinary sodium excretion showed significant positive correlation with BMI, frequency of eating out, expenditure of eating out, salty taste assessment and high-salt dietary behavior. Analysis of urinary sodium excretion showed significant positive correlation with intake frequencies of cabbage kimchi, broiled fish, feast noodle and rice with leaf wraps. Based on the results of multiple regression, urinary sodium excretion was found to be related to intake frequencies of cabbage kimchi, broiled fish, rice with leaf wraps and high score of high-salt dietary behavior.

• Korean Parent-Child Health Journal
• /
• v.3 no.2
• /
• pp.25-40
• /
• 2000

The purpose of this study is to identify the sleep/activity patterns of neonates and to provide a baseline data in developing an effective maternal-child nursing intervention strategies. The subjects of this study were 57 normal newborn babies from birth to 4 weeks of age, who visited the Postpartum Care Center and two General Hospitals and One Local clinic in Taejon. The data were collected from October 28th, 1999 to April 28th, 2000. The instrument used in this study was NCASA developed by Barnard and validated by the Academic Society of Parent-Child Health. The data were analyzed with the SPSS PC+ 7.5 for window program using means, standard deviation, one-way ANOVA. The results of this study were as follows: 1. The mean amount of daytime sleep was 7.45 hours, nighttime sleep was 4.27 hours, and the total daily sleep was 11.72 hours. The mean amount of longest sleep period was 4.32 hours. The mean regularity of daytime sleep was 35.55%, the nighttime sleep was 44.82%, and the total daily sleep was 39.02%. The mean frequency of nighttime awakenings was 2.44 times. 2. The mean amount of daytime awake periods was 8.54 hours, the nighttime awake periods was 3.72 hours, and the daily total awake periods was 12.27 hours. The mean amount of the longest awake period was 3.98 hours. 3. The mean frequency of daytime feeding was 5.18 times, the nighttime feeding was 2.50 times, and the total daily feeding was 7.49. The mean of regularity of total daily feeding was 61.34%. 4. According to an analysis of sleep patterns based on newborn's age, there were some statistically significant differences noted in the following factors ; amount of nighttime sleep (F=7.65, p=.002), longest sleep period(F=5.84, P=.006). 5. According to an analysis of activity patterns based on newborn's age, there were some statistically significant differences noted in the following factors ; amount of nighttime activity (F=7.64, P=.002), longest activity period (F=4.34, P=.020), frequency of nighttime feeding(F=3.89, p=.029), frequency of total daily feeding(F=3.76, P=.033), and regularity of daily feeding(F=4.66, P=.016). In conclusion, the newborn baby slept more during the daytime than nighttime and more active during the daytime. And there were some irregular sleep/activity pattern noted during 1 to 2 weeks of newborn baby. The results of this study will contribute to maternal-child health nursing practice and nursing research, and provide an information to parents about what to expect their newborn baby.

• Women's Health Nursing
• /
• v.5 no.2
• /
• pp.204-221
• /
• 1999

Due to the ever increasing life-span of human beings, the average woman is living well into her 70's. Henceforth, they spend at least one-third of their life after menopause. Climacteric encompasses the time preceding, during, and proceeding menopause : a transitional period of shifting from the period of being fertile to the period of senescence. In other words, this is the time at which they lose the ability to reproduce. Menopause can influence a woman's sexual life immensely due to the physiological, social, and psychological changes that occur during that period. In korea, where some women still live according to Confucian Culture in terms of sexology, nurses can play a vital role in the dissemination of sexual facts to women. This study was designed to clarity the characteristic and satisfaction of sexual life. This was done according to the classification of three types of climacteric women : pre-meno-pausal, menopausal, and post-menopausal. I studied 159 climacteric women between the ages of 45 & 59, living in or around the vicinity of Taegu City. This study utilized the investigative tools for sexual life patterns which were constructed with field experts' consultation and reference review by the author. The sexual satisfaction was translated from DSFI. The climacteric symptoms were invented by Kupperman, This research is descriptive. The data was collected between July 15, 1998 and October 14, 1998. Statistical analysis was performed using ANOVA and Pearson Correlations, and was computed with the SPSS program. The results obtained are summarized as follows; The frequency of sexual activity was highest in pre-menopause and declined after menopause. The frequency of genital caressing declined after menopause. The difference between the frequency of masturbation and coital pain was not significant according to the classification set forth in this experiment. Congruently, the frequency of orgasms declined after menopause. The mean satisfaction of sexual life is 27.1 years. The range of expected score is 9-45 years of age. Satisfaction was highest in the pre-menopausal group and proved to be statistically significant. Some of the general characteristics that affected the satisfaction a woman's sexual life in the climacteric stage during this project were ; age, income, satisfaction in younger pre-menopausal and the large income group than the other experimental groups. The climacteric symptoms were conversely correlated with the satisfaction in one's sexual life.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2003.11a
• /
• pp.403-406
• /
• 2003

For small capacity rectifier circuits such as these for consumer electronics and appliances, capacitor input type rectifier circuits are generally used. Consequently, various harmonics generated within the power system become a serious problem. Various studies of this effect have been presented previously. However, most of these employ switching devices, such as FET and the like. The absence of switching devices mattes systems more tolerant to over-load and brings low radio noise benefits. We propose a power factor correction scheme using a LC resonant in commercial frequency without switching devices. In this method It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency, Hence, the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh orders are much reduced The result are confirmed by the theoretical and experimental implementations.