• Human Ecology Research
• /
• v.59 no.2
• /
• pp.233-243
• /
• 2021

This study examined the longitudinal effects of media usage by early school-age children and of maternal parenting stress on children's school adjustment. The study focused on the mediating effect of executive function difficulty. Longitudinal data to examine the hypothetical model were drawn from the eighth (2015) through tenth (2017) waves of the Panel Study of Korean Children (PSKC) collected by the Korea Institute of Child Care and Education (KICCE). A total of 581 children (293 boys and 288 girls) and their mothers were included. Confirmatory factor analysis, structural equation model, and bootstrapping analysis were applied using SPSS 25.0 and Amos 26.0. The results are as follows. First, no significant correlation was found between early school-age children's media usage and maternal parenting stress. Second, neither media usage by early school-age children nor maternal parenting stress were found to directly affect children's school adjustment. Third, media usage by early school-age children and maternal parenting stress were shown to indirectly affect children's school adjustment via executive function difficulties. In other words, higher levels of media usage by early school-age children and maternal parenting stress during the first grade lead to greater executive function difficulties after a year, which, in turn, lead to a lower level of school adjustment in the third grade. This study indicates the need to develop practical support for the psychological wellbeing of mothers while they are performing their role as a parent and for children in maintaining suitable levels of media usage during early childhood.

• Communications of Mathematical Education
• /
• v.35 no.1
• /
• pp.97-118
• /
• 2021

Since the characteristics of teachers that affect mathematics academic achievement are constantly changing and affecting mathematics achievement, longitudinal studies that can predict and analyze growth are needed. This study used data from middle and high school students from 2013(first year of middle school) to 2017(second year of high school) of the Seoul Education Longitudibal Study(SELS). By classifying the longitudinal changes in mathematics academic achievement into similar subgroups, the direct influence of teachers' characteristics(professionalism, expectations, academic feedback) perceived by students on the longitudinal changes in mathematics academic achievement was examined. As a result of the study, it was found that the characteristics of mathematics teachers(professional performance, expectation, and academic feedback) in group 1(343 students), which included the top 14.5% of students, did not directly affect longitudinal changes in mathematics academic achievement. Students in the middle 2nd group(745, 32.2%) had academic feedback from the mathematics teacher, and the 2nd group(1225 students) in the lower 53%, which included most of the students, showed that the expectations of the mathematics teacher were the longitudinal mathematics achievement. The change has been shown to have a direct effect. This suggests that support for teaching and learning should also reflect this, as the direct influence of teachers' professionalism, expectations, and academic feedback on longitudinal changes in mathematics academic achievement is different according to the characteristics and dispositions of students.

• Journal of Korean Academy of Nursing
• /
• v.33 no.5
• /
• pp.562-569
• /
• 2003

Purpose: The purpose of this longitudinal prospective study was to assess changes in fatigue and quality of life for a 6-week course of radiotherapy. Method: A descriptive and longitudinal design was used to this study. Twenty-three subjects receiving radiotherapy from a radiotherapy clinic of a general hospital completed the questionnaires. Fatigue was measured using Lee's scale(1999) and quality of life using Yang's scale(2002) weekly for 6 weeks. Result: Fatigue significantly increased(F=6.043, p=.000), and quality of life significantly decreased (F=3.938, p=.003) and physical symptoms also significantly increased(F=2.432, p=.039) during a 6-week radiotherapy. Multiple regression analysis revealed that fatigue at the first week and physical symptoms at the 6th week were the significant affecting variables(60.1% of the variance) on fatigue. And 63.2% of the variance in quality of life was explained by quality of life and fatigue at the first week and body weight change for 6 weeks radiotherapy. Conclusion: Based on these results, the fatigue and quality of life at the beginning time of radiotherapy have a lasting impact throughout the course of treatment. It suggests that nurses provide patients with information about the occurrence of fatigue during radiotherapy and the practical methods of intervening physical symptoms.

• Women's Health Nursing
• /
• v.8 no.1
• /
• pp.55-68
• /
• 2002

While the survival rate of preterm infants and employment rates of mothers with infants have been dramatically increasing, little is known about the impact of maternal employment and having premature infants on maternal health recovery after delivery. The purpose of this longitudinal study was to examine differences in postpartum health by mother's employment and infant's prematurity over time during the first 3 months postpartum. The study used a longitudinal design and was secondary data analysis from a large study. A convenience sample of 132 mothers was recruited with mothers who had fullterm or preterm infants through the postpartum unit. They were followed up for 3 times (at 1-2 days, 6 weeks, and 3 months) during the first 3 months postpartum period. Level of fatigue and hysical symptoms were indicators for postpartum physical health; Positive affect and negative affect were assessed for postpartum mental health, and role functional status after childbirth was for role performance. Finding indicated that health indicators changed significantly over time but there was no main or interaction effect for maternal employment status. There were main effects of infant's prematurity on positive affect, negative affect, and role functional status (self-care and social and community activities). This study enhanced the understanding of postpartum health of mothers with preterm infants as well as those with fullterm infants during the postpartum period.

• Structural Engineering and Mechanics
• /
• v.72 no.5
• /
• pp.597-615
• /
• 2019

The paper studies the dispersion of the axisymmetric longitudinal wave propagating in the "hollow cylinder + surrounding medium" system with inhomogeneous initial stresses caused by the uniformly distributed radial compressional forces acting at infinity. Up to now in the world literature, there exist only a few investigations related to the wave dispersion in a hollow cylinder with inhomogeneous initial stresses. Therefore, this paper is one of the first attempts in this field in the sense of the development of investigations for the case where the cylinder is surrounded with an infinite medium. The three-dimensional linearized theory of elastic waves is used for describing the considered wave propagation problem and, for a solution to the corresponding mathematical problem, the discrete-analytical solution method is developed and employed. The corresponding dispersion equation is obtained and this equation is solved numerically and, as a result of this solution, the dispersion curves are constructed for the first and second modes. By analyzing these curves, the character of the influence of the inhomogeneous initial stresses on the dispersion curves is established. In particular, it is established that as a result of the inhomogeneity of the initial stresses both new dispersion curves and the "band gap" for the wave frequencies can appear.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05a
• /
• pp.538-541
• /
• 2006

PSC(Prestressed Concrete) box girder bridges have been widely applied in Korea. A number of these bridges have been built by the segmental construction method in the longitudinal direction and(or) vertically along the cross-sectional depth with MSS(Moving Scaffolding System). An actual 2-span continuous PSC box girder bridge of Kyeongbu high speed railway was selected and instrumented with 96 vibrating wire embedded type strain gauges and 2 thermocouples. The long-term behavior of the bridge was monitored through two major points located at mid-span of the first span and at the internal support. Data collection started just after the casting of the first segment (U section). Concrete strain and temperature data were gathered regularly by a data logger (CR10) during 600 days under and after construction. According to this measurement, the parabolic longitudinal strain distribution in the top slab at mid-span is shown. And also, the same distribution at the interior support is shown. The compressive strains at the cantilever region are larger than at the web position and the internal part in the top slab. Strain difference largely happened during the early construction period.

• Women's Health Nursing
• /
• v.12 no.1
• /
• pp.53-60
• /
• 2006

Purpose: This study aimed to explore changes in symptom distress and functional status in gynecologic cancer patients during the entire treatment cycles of chemotherapy. Methods: A prospective and longitudinal study with repeated measures was designed. Symptom Distress Scale and Karnofsky Performance Status Index were included in a daily log developed for self-administration. A total of 39 patients with a mean age of 48.4 years participated. Results: The levels of symptom distress and functional status changed significantly over the six cycles. Symptom distress kept increasing until its peak at the fourth cycle, while the functional status scored lowest at the first cycle, then it improved as the cycle repeated. In each cycle, symptom distress was marked higher during the first 6 days accompanying poor functional status. However, both changes did not recover completely until the end of each cycle. Conclusion: Nursing assessment and intervention need to be provided based on these changing patterns to help cancer patients cope and adjust successfully during the long treatment period. Further studies are needed to examine the impact of the major symptoms on psychological responses, quality of life, and outcomes of the cancer treatments.

• Journal of Nutrition and Health
• /
• v.32 no.1
• /
• pp.75-82
• /
• 1999

In order to investigate the longitudinal changes on zinc secretion of lactating women and zinc intake of breast-fed infants, we examined 20 lactating women(10 primipare and 10 multipare) and their infants during the first 90 days postpartum. We measured the consumed volume of human milk by test-weighing method and zinc concentration by atomic absorption spectophotometry after wet digestion. Weight gain of infants was -5.7, 54.1, 46.3, 42.0 and 32.3g/day at 7, 15, 30, 60 and 90 days postpartum, respectively. The secretion volume of human milk was 527, 608, 724, 841 and 798g/day respectively. The consumed volume of human milk of breast-fed infants was 432, 503, 603, 715 and 715g/day. The intake level of breast milk to secretion volume reached 85.0% in average. The zinc concentration of the milk was 4.29, 3.32, 2.52, 1.62 and 1.18mg/l, and the zinc intake of breast-fed infants was 1.80, 1.69, 1.45, 1.15 and 0.70mg/day. Zine intake per body weight of infants averaged 0.32mg/kg/day during the first 90 days postpartum. The average zinc intake of breast-fed infants was 1.36mg/day, which is 27.2% of the recommended daily allowance for 0-4-month-old infants.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.379-385
• /
• 2010

Mechanism of combustion frequencies occurring during combustion is experimentally investigated in a model combustor with V-gutter flameholder. The combustor has a long duct shape with a cross section area of $40{\times}40mm$. The v-gutter type flameholder with 10, 12, 14mm width is mounted at the side wall of combustor. CNG were used as fuel, and the fuel was injected transversely into air crossflow. It is found that combustion frequencies were considered as first longitudinal mode caused by combustor geometry. And it is found that flameholder length affects the flame holding range. Also, it is observed first longitudinal pressure oscillations make significant changes of flame structure.

• Steel and Composite Structures
• /
• v.27 no.4
• /
• pp.525-536
• /
• 2018

This paper focuses on the application of the first-order shear deformation theory (FSDT) to thermo-elastic static problems of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) cylindrical pressure vessels. A symmetric displacement field is considered as unknown function along the longitudinal direction, whereas a linear distribution is assumed along the thickness direction. The cylindrical pressure vessels are subjected to an inner and outer pressure under a temperature increase. Different patterns of reinforcement are applied as distribution of CNTs. The effective material properties of FG-CNTRC cylindrical pressure vessels are measured based on the rule of mixture, whereas the governing equations of the problem are here derived through the principle of virtual works. A large parametric investigation studies the effect of some significant parameters, such as the pattern and volume fraction of CNTs, on the longitudinal distribution of deformation, strain and stress components, as useful tool for practical engineering applications.