• Smart Structures and Systems
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• v.20 no.4
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• pp.473-481
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• 2017

This study suggests a simple, convenient and non-destructive method for investigation of the Young's modulus detection in stepped shafts which only utilizes the first-order resonant frequency in flexural mode and dimensions of structures. The method is based on the impulse excitation technique (IET) to pick up the fundamental resonant frequencies. The standard Young's modulus detection formulas for rectangular and circular cross-sections are well investigated in literatures. However, the Young's modulus of stepped shafts can not be directly detected using the formula for a beam with rectangular or circular cross-section. A response surface method (RSM) is introduced to design numerical simulation experiments to build up experimental formula to detect Young's modulus of stepped shafts. The numerical simulation performed by finite element method (FEM) to obtain enough simulation data for RSM analysis. After analysis and calculation, the relationship of flexural resonant frequencies, dimensions of stepped shafts and Young's modulus is obtained. Numerical simulations and experimental investigations show that the IET method can be used to investigate Young's modulus in stepped shafts, and the FEM simulation and RSM based IET formula proposed in this paper is applicable to calculate the Young's modulus in stepped shaft. The method can be further developed to detect mechanical parameters of more complicated structures using the combination of FEM simulation and RSM.

• Journal of the Korean Home Economics Association
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• v.36 no.5
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• pp.17-27
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• 1998

The need for periodic investigation on human growth rate and somatotypes has been increased because the scientific development and environmental factors have effected a lot on them recently. This study aimed to investigate the changes of the 638 female somatotypes in the age of 18-54 obtained by direct and indirect measurement. The measurement data were divided into 4 groups early young women age group (18-54), late young women age group (25-34), early middle age group (35-44), late middle age group (45-54) and compared each other based on each group by age. The results obtained from this study were as follows: 1. According to Mollison Curve based on the early young women, items of depth decreased overall and pp.P. length & shoulder length increased as the age increased. The circumference, breadth and thickness tended to increase, especially waist girth and thickness of waist increased markedly. The data showed that the increase rate of thickness was higher than that of breadth. 2. Gradual somatotype changes were observed by overlapping projection drawings obtained by direct measurement. Compared with the young women, the middle aged showed lower should point depth and hip line & crotch depth line were lengthened significantly. No significant difference was observed in overlapping of the early young women and the late young women' figure, neither was in early middle aged and the late middle aged. 3. By overlapping the side view of the young women group (18-37) and middle aged group (35-54), no significant postural characteristics were found, while the back tended to bend forward and the abdomen and hip appeared to get fat.

• Korean Journal of Child Studies
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• v.32 no.3
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• pp.121-142
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• 2011

This study explores the structural relationships between personal factors (young children's self-esteem and language ability) and environmental factors (mother's acculturation, parenting, and teacher's multi-cultural education attitude) on young children's adjustment to early childhood educational institution in multi-cultural families. 150 young children in multi-cultural families of aged 3, 4, and 5, their mothers, and 108 classroom teachers participated in this study. The results of this investigation reveal the following : (1) Mother's integrative acculturation significantly affected mother's parenting. (2) The relationship between mother's acculturation and young children's adjustment to early childhood educational institution in multi-cultural families are significantly mediated by mother's parenting and the young children's self-esteem. (3) Young children's language ability in multi-cultural families significantly affected their degree of adjustment to early childhood educational institution.

• Korean Journal of Childcare and Education
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• v.12 no.5
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• pp.17-45
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• 2016

This study aimed to investigate the effect of a young children's happiness program in relation with the Nuri curriculum on young children's happiness and self-esteem. Study subjects included 37 children aged 5 (experimental group 20, comparative group 17) enrolled in A day care center and D day care center located in K district, Seoul. As for the research procedure, an experiment was conducted 48 times in 18 weeks, and the experimental group carried out the children's happiness program linked with the Nuri curriculum. In contrast, the comparative group conducted general activities focusing on the subjects according to the Nuri curriculum. Study results show that there was a significant difference amongst 9 sub-domains related to young children's happiness (health, emotion, immersion, recognition and achievement, parent-child relationship, teacher-child relationship, peer relationship, spirituality, life satisfaction) and 3 sub-domains related to self-esteem (start and spirit of independence, sociality emotionality, academic achievement). Results of this study prove that the children's happiness program in relation with the Nuri curriculum is effective for increasing young children's happiness and self-esteem, and could be used as preliminary data for the possibility of a happiness program in early childhood education settings and happiness education in the future.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.203-210
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• 2012

Traffic accident risk of young drivers(less than 25) is reported to have 8 times as high as that of middle aged drivers(between 30 and 49). Despite the rise of traffic accident risk, few have been attempted to take a look into driving characteristics of young drivers. The purpose of this paper is to analyze age-specific risks of young driver by means of database of insurance and vehicle inspection, thereby collecting data such as age, vehicle mileage, injuries and so on. We conducted Data-Mining(CART) and Portfolio analysis according to age groups(every 10 years). The conclusions which can be drawn from this empirical study are as follows: (1) Despite the fact that young drivers have low vehicle mileage, the rate of fatality is relatively high. (2) Being concerned of vehicle mileage, 24,000km of driving experience is thought to be critical in differing in fatality rate. Having annual average mileage fewer than 24,169 km, accident frequency is relatively lower than that exceeding 24,169 km(1,571 cases). Backed upon these, some recommendations about driver's license system for young driver to improve are given.

• Journal of Nutrition and Health
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• v.31 no.9
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• pp.1404-1410
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• 1998

The purpose of this study was to investigate the effects of calcium intake levels on magnesium utilization in young and adult rats fed various levels of calcium(50, 100 or 200% of requirement) for 3 weeks. Feed intake, body weight gain, and feed efficiency ratios of the young group were significantly higher than those of the adult group. In calcium levels of tissues, serum calcium levels in young group were higher than in the adult group and kidney calcium levels in HCa(high-calcium group) were higher than in other groups. There was no significant difference in magnesium intake among age and diet groups. However, magnesium excretions through feces and urine in the adult group were higher than in the young group. Therefore, magnesium retention in the young group was higher than in the adult group. Especially in the young group, fecal magnesium excretion was increased with increasing levels of dietary calcium. Serum magnesium levels were lowest in YHCa(young 8t high-calcium) group, and there was no significant difference in liver and kidney levels among the calcium-diet groups. These results indicate that high calcium consumption promotes of fecal magnesium excretion and decreased magnesium retention rates in growing rats. Therefore, it is suggested that mineral interactions should be considered in the supplementation of dietary calcium intake for growth. (Korean J Nutrition 31(9) 1404-1410, 1998)

• Journal of Nutrition and Health
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• v.25 no.1
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• pp.32-41
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• 1992

A study was conducted to estimate Na intake in 30 young and 62 middle-aged female Koreans. For each subject, nondiscretionary Na intake was estimated from 2-day dietary records optimum gustation of salt was tested using beef broth with different salt concentra-tions. and 24-hour urinary Na excretion was measeured from pooled 2-day urine samples. Total daily Na intake was calculated from 24-hour urinary excretion and discretionary Na intake was calculated as difference between total and nondiscretionary Na intake was calculated as difference between total and nondiscretionary Na intake. Mean daily 24-hour urinary Na excretion of the young and middle-aged women was 184.6mEq and 224.6mEq. Mean values of optimum gustation of salt in young and middle-aged subjects were 0.431% and 0.489% The differences between the two groups were significant. Nodiscre-tionary Na intakes of the two groups were not significantly different, . Calculated total and discretionary Na intake of middle-aged women(245.1mEq) were significantly higher than young women(220.3mEq and 211.0mEq) were significantly higher than young women(210, 3mEq and 169, 7mEq) Percent of discretionary to total Na intake was 85.7% in middle-aged and 79.4% in young women. Age BMI urinary Na and K excretions optimum gustation of salt were signficantly correlated with blood pressure of the subjects. Results of the present study confirms the high level of sodium intake especia-lly of discretionary Na intake among Korean women.

• Korean Journal of Child Studies
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• v.33 no.5
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• pp.139-161
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• 2012

The purpose of this study was to analyze the relationships of mothers' parenting stress and young children's adjustment to the child care centers they attend. The subjects for this study comprised 401 young children from 1 to 4 years of age from 11 child care centers in C-si, Chungnam, and their mothers. The results of this study were as follows : First, there were no significant differences in the parenting stress of mothers related to whether they were working or not, the age of the children nor their gender Second, there were no significant differences in the adjustment of young children to their child care center related to their mothers' work status nor age of the children themselves. However, there was a significant difference in relation to the gender of the young children in that girls were better in their adjustment to the child care center than boys. Third, a negative correlation appeared between mothers' parenting stress and their young children's adjustment to the child care center in that the higher maternal parenting stress was, the greater the difficulties for their young children in their adjustment to the child care center. There were significant negatively correlations between most sub-factors of maternal parenting stress and the adjustment of those children to the child care center.

• International Journal of Human Ecology
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• v.8 no.2
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• pp.61-74
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• 2007

Adolescents from stepfamilies have been considered as at-risk group of mental and behavioral problems. This study aims to determine whether there is a group difference of emotional or behavior disturbance between young people in step and non-stepfamilies and whether risk factors linked to emotional and behavior symptoms of young people in stepfamilies are different from those of girls in non-stepfamilies. The study used 'the Mental Health of Children and Young People in Great Britain, 2004 (MHCYP 2004)'. In the MHCYP 2004, the Rutter Problem Behavior Questionnaire, the Strengths and Difficulties Questionnaire (SDQ), and Child Behavior Checklist (CBCL) were administered to parents, teachers, and children drawn from young people aged 5-17 living in private households in England, Scotland (including the Highlands and Islands) and Wales. The total of 2,471 samples of aged 13 through 17 from them were selected for this study. The selected data was analyzed using SPSS. The findings showed group differences in emotional and behavior symptoms between young people in step and non-stepfamilies: Young people from stepfamilies were more emotional and have behavioral disturbances than those from nonstepfamilies. The result also confirmed the different risk factors associated with emotional behavior problems. The study supports that professionals need to develop effective treatment and preventive approaches designed for young people in stepfamilies who may have different risk factors different from those in non-stepfamilies.

• Nuclear Engineering and Technology
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• v.41 no.3
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• pp.327-334
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• 2009

Elastic wave is one of the most useful tools for non-destructive tests in nuclear power plants. Since the elastic properties are indispensable for analyzing the behaviors of elastic waves, they should be predetermined within an acceptable accuracy. Nuclear power plants are exposed to harsh environmental conditions and hence the structures are degraded. It means that the Young's modulus becomes unreliable and in-situ measurement of Young's modulus is required from an engineering point of view. Young's modulus is estimated from the group velocity of propagating waves. Because the flexural wave of a plate is inherently dispersive, the group velocity is not clearly evaluated in temporal signal analysis. In order to overcome such ambiguity in estimation of group velocity, Wigner-Ville distribution as the time-frequency analysis technique was proposed and utilized. To verify the proposed method, experiments for steel and acryl plates were performed with accelerometers. The results show good estimation of the Young's modulus of two plates.