• The Journal of Engineering Geology
• /
• v.22 no.1
• /
• pp.27-37
• /
• 2012

To investigate the effect of aquifer disturbance on hydraulic properties while well drilling at unconsolidated aquifer, the following tests were conducted: the surge block and air-surging methods, which are well development methods used after well drilling; and step-drawdown tests and constant-rate pumping tests, which are used to assess changes in the aquifer after well drilling and development. The result of step-drawdown tests indicated that drawdown for a pumping-rate of $700m^3/day$ was 21.62 m after well development, decreasing 4.39 m from 26.01 m after well drilling. The skin factor used to identify the well properties decreased from 7.92 after well drilling to 5.04 after well development, respectively, which shows the improvement of well. Constant-rate pumping tests revealed a small increase in aquifer transmissivity after well development at MW-2, -3, and -4, centering around pumping well, from $1.684{\times}10^{-3}{\sim}4.490{\times}10^{-3}m^2/sec$ to $4.002{\times}10^{-3}{\sim}4.939{\times}10^{-3}m^2/sec$. MW-1, however, showed decline in hydraulic conductivity from $1.018{\times}10^{-2}m^2/sec$ to $6.988{\times}10^{-3}m^2/sec$, which was caused by a small decrease of aquifer permeability around monitoring well MW-1 due to latent factor of air interception and clogging in aquifer during surging. This finding indicates that fine particles have an effect on hydraulic properties at unconsolidated aquifers during well drilling; therefore, we consider that well drilling and development have an effect on hydraulic properties.

• Sleep Medicine and Psychophysiology
• /
• v.22 no.2
• /
• pp.64-69
• /
• 2015

Objectives: We investigated whether sleep behaviors, severity of insomnia and circadian typology are associated with quality of life among Gyeongsang National University (GNU) medical students. Methods: Questionnaires were distributed to 46 fourth-year students of GNU Medical School. The hospital anxiety-depression scale, insomnia severity index (ISI), morningness-eveningness questionnaire (MEQ) and WHO Quality of Life-BREF (WHOQOL-BREF) were used. Results: Quality of life in terms of physical health was associated with age, weekday total sleep time (TST), weekend TST, catch up sleep, depression, ISI score, and MEQ score. Quality of life in terms of psychological health was correlated to weekday and weekend TST, anxiety, ISI score and MEQ score. Sex, weekday TST, depression, and ISI score were revealed to influence the social aspect of quality of life, and weekday and weekend TST, and ISI score were associated with quality of life in terms of environment. Multiple regression analysis showed that better sleep quality predicted to a higher quality of life in terms of physical, psychological and environmental health, and eveningness was associated with a better quality of life in terms of physical and psychological health. Conclusion: It is concluded that physical, psychological, and environmental aspects of quality of life were associated with quality of sleep and that physical and psychological aspects of quality of life were related to eveningness in GNU medical students. Therefore, it is equally important to treat emotional problem as well as improve sleep quality.

• Korean Journal of Psychosomatic Medicine
• /
• v.26 no.2
• /
• pp.102-111
• /
• 2018

Objectives : This study aimed to investigate the relationship between personality characteristics of medical students at their admission and the level of depression, anxiety, and resilience at their third year. Methods : Self-reported questionnaires were conducted to the students at the beginning of the first year and the third year. When the students in their first year, they performed the personality assessment inventory, the Beck depression inventory, and the Beck anxiety inventory. When they were in the third year, the students answered the composite Scale of morningness and Conner-Davidson resilience scale-10 in addition to the BDI and BAI. Multiple linear regression analyses were performed to identify predictors of the level of depression, anxiety, and resilience. Results : Of the subscales of depression in the PAI, the physiological depression (${\beta}=-0.285$, p=0.049) associated with increase in the depression from the first to the third year. Among the anxiety-related disorder subscale in the PAI phobia (${\beta}=0.119$, p=0.022) and traumatic stress (${\beta}=0.375$, p=0.007) associated with the level of depression at third grade. Somatization (${\beta}=0.631$, p<0.001) in the PAI associated with the level of anxiety at third year. The anxiety (${\beta}=-0.531$, p<0.001) in the PAI was positive associated with the resilience at third grade. Conclusions : This study showed that certain personality characteristics at admission had significant relationships with the level of depression, anxiety, and resilience at the third grade medical students.

• Journal of Intelligence and Information Systems
• /
• v.28 no.3
• /
• pp.105-117
• /
• 2022

This study analyzes the effects between stock returns and interest rate spread, difference between long-term and short-term interest rate through the polynomial linear regression analysis. The existing research concentrated on the business forecast through the interest rate spread focusing on the US market. The previous studies verified the interest rate spread based on the leading indicators of business forecast by moderating the period of long-term/short-term interest rates and analyzing the degree of leading. After the 7th reform of composite indices of business indicators in Korea of 2006, the interest rate spread was included in the items of composing the business leading indicators, which is utilized till today. Nevertheless, there are a few research on stock returns of each industry and interest rate spread in domestic stock market. Therefore, this study analyzed the stock returns of each industry and interest rate spread targeting Korean stock market. This study selected the long-term/short-term interest rates with high causality through the regression analysis, and then understood the correlations with each leading period and industry. To overcome the limitation of the simple linear regression analysis, polynomial linear regression analysis is used, which raised explanatory power. As a result, the high causality was verified when using differences between returns of corporate bond(AA-) without guarantee for three years by leading six months and call rate returns as interest rate spread. In addition, analyzing the stock returns of each industry, the relation between the relevant interest rate spread and returns of the automobile industry was the closest. This study is significant in the aspect of verifying the causality of interest rate spread, business forecast, and stock returns in Korea. Even though it could be limited to forecast the stock price by using only the interest rate spread, it would be working as a strong factor when it is properly utilized with other various factors.

• Journal of Wetlands Research
• /
• v.25 no.3
• /
• pp.205-212
• /
• 2023

This study was attempted to find out how the ecological niche and interspecies relationship of Quercus aliena and Q. serrata, which are the main constituents of potential natural vegetation along the riverside of mountains in Korea, under climate change conditions. To this end, soil moisture and soil nutrients were treated with 4 grad ients under climate change conditions with elevated CO₂ and temperature, plants we re harvested at the end of the growing season, growth responses of traits were measured, ecological niche breadth and overlap were calculated, and it was compared with that of the control group(ambient condition). In addition, the relationship between the two species was analyzed by principal component analysis using trait values. As a result, the ecological niche breadth of Q. aliena was wider than that of Q. serrata under the moisture environment conditions under climate change. Under nutrient conditions, the ecological niche of the two species were similar. In addition, the ecological overlap for soil moisture of Q. aliena and Q. serrata was wider than the soil nutrient gradient under climate change. The species with traits in which the increase in ecological niche breadth due to climate change occurred more than the decrease was Q. aliena in both water and nutrient gradients. And in the responses of the population level, due to climate change, the adaptability of Q. aliena was higher than that of Q. serrata under the soil moisture condition, but the two species were similar under the nutrient condition. These results mean that the competition between the two species occurs more severely in the water environment under climate change conditions, and at that time, Q. aliena has higher adaptability than Q. serrata.