• 한국직업건강간호학회지
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• 제15권2호
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• pp.115-125
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• 2006

Purpose: This study analyzed the amount of stress and the different effects according to the working times(hours) of a week in two groups: more than 40 hours a week and less than 40 hours a week. Method: The study was conducted from November 1st 2005 to December 15th 2005. The purpose of the study has already been explained in the experiment objectives. 20 copies of evaluation forms were sent by mail to 50 different health sections of participating work sites. A total of 1,000 copies were sent out and 870 were sent back. Within the forms, sent back 120 copies had insufficient data, so 750 copies of evaluation forms were analyzed. Result: Working stress for under 40 hours of working time showed a total of 46.10 points and 47.18 for over 40 hours of working time. For over 40 hours, job demand and occupational climate was high and under 40 hours showed a high rate of job control. For under 40 hours of working time, the factors that caused stress were female, irregular diet habit, age of 30's, nonmanufacturing, and single. For over 40 hours of working time, the factors that causes stress were age of over 40, when the number of employees is 500~999, high rate of fatigue, when the position of the employee is higher then section chief, and when the work amount is high. Conclusion: The stress rate showed significantly higher in over 40 hours of working time. Therefore, adequate working hour distribution and health promotion programs are needed. The factors that cause stress in both under and over 40 hours of working time differed. Therefore, a distinguished program to control work stress for additional working time is needed.

• 한국보육지원학회지
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• 제18권2호
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• pp.105-124
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• 2022

Objective: This study investigated the double mediating effects of maternal and paternal parenting stress and the regularity of children's daily routines in the association between maternal and paternal parenting time and children's self-regulation. Methods: A total of 235 preschool children aged 4-5 years and their mothers and fathers participated in the study. Parenting time, parenting stress, and children's self-regulation were assessed using both mothers' and fathers' reports, but the regularity of daily routines was assessed using mothers' reports only. The data was analyzed using SEM in Mplus 8.2. Results: Mothers' and fathers' parenting stress appeared to have cross-spousal mediated effects of their parenting time on children's self-regulation. Higher levels of mothers' and fathers' parenting time predicted higher levels of children's self-regulation through only a lower level of mothers' parenting stress and a higher level of the regularity of daily routines. Conclusion/Implications: Findings indicated that parents' parenting time played a significant protective factor in reducing parenting stress and increasing the regularity of daily routines among family members. This cross-spousal influence on parenting process can inform the development of prevention programs and parenting education to promote self-regulation skills among preschool children.

• 대한간호학회지
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• 제34권7호
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• pp.1265-1276
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• 2004

Purpose: This study tries to explore mothers' stress patterns and the related factors influencing mothers' stress over time after giving birth to premature babies. Method: Eighty four mothers who had given birth to premature babies were selected from Hospitals in B city. Data was collected using a self-reporting questionnaire that the mothers' stress level. Result: The mothers' stress after giving birth to premature babies gradually diminished and the stress pattern of mothers changed over time. Mother's age, occupation, income level, gestational period of the measures baby, weight at birth, nutrition type, lactation mode, number of complications, and existence or non-existence of an operation were analyzed as the factors that affected the mother's stress. Conclusion: The stress pattern of mothers giving birth to premature babies changed overtime. Based on the study results, it is considered that the nursing intervention programs should be developed in order to reduce the stress of premature baby's mothers with time elapse.

• 대한가정학회지
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• 제49권9호
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• pp.121-130
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• 2011

The purpose of this study was to explore potential correlation between the amount of time children spent in child care centers and their daily stress levels. The subjects of this study were 165 children (aged 2~5) who attended a child care center in Seoul. Children were interviewed individually, and tested using 23 picture cards which describe a range of stressful situations. The results of this study were as follows: the children's age led to significant differences in their stress level. The age at which the children first entered the child care center had no significant impact on their stress level. However, the times spent in child care centers showed a significant correlation with stress. The longer time the child spent in the center, the higher the degree of stress they encountered.

• Journal of the Korean Wood Science and Technology
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• 제27권4호
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• pp.43-50
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• 1999

The safety-evaluation of ancient wood structures has been executed with only visual inspection. The application of NDE(nondestructive evaluation) is required because the visual inspection has many restrictions. Among many NDE techniques, the stress wave technique was used in this research. This study focused on evaluating the extent of decay in members of ancient structures, using stress wave nondestructive technique. For application of stress wave technique to ancient structures, the threshold time which divides members into categories according to degree of decay should be determined in advance. Stress wave timer (Metriguard Model 239A) was used in this study, specimens used in this research were the members obtained from six ancient structures. All specimens were identified as Hard Pine(Pinus densiflora S. et Z. or Pinus thunbergii P.) by microscope. Each member was tested with stress wave passing radially through the pith. In this study, the stress wave time of $12{\mu}s$/cm could distinguish between sound and decayed specimens with accuracy of 77.5 percent. Also, decayed specimens could be separated into moderate and severe categories by stress wave time of $20{\mu}s$/cm. Among the three decay location groups (exterior, mixed, interior), the exterior group could be classified into sound, moderate and severe decay with the greatest accuracy. Stress wave transit time was not sensitive to small decay pockets located in interior of the member.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.773-777
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• 1995

This thesis attempt to explore the shape of stress wave propagation of 3-dimensional stress field which is made in the process of time increment. A finite element code about 3-dimensional stress wave propagation is developed for investigating the changing shape of the fracture by the impact load. The Finite Element Code, which is the solution for the 3-dimensional stress wave analysis, based on Galerkins and Newmark- .betha. method at time increment step. The tensile stress and compressive stress become larger with the order of the middle, the upper and the opposite layers when the impact load is applied. In a while the shear stress become larger according to the order of the upper, the middle and the opposite layers when impact load applied.

• 한국강구조학회 논문집
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• 제8권4호통권29호
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• pp.19-29
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• 1996

In this paper, it is presumed that the stress time history was generated by simulation method and investigated compatibility in regard to the reappearance of stress time history. In this procedure, the identified frequency distribution of stress range of the steel railroad bridge varies with the rational values of cut off point and bar width. Thus, we show variable aspect of the equivalent stress range results from change of cut off point and bar width. In addition, we analyze the variable of RMC and RMS model due to the cut off point and bar width of the measured stress history which influencs the prediction of fatigue life in the steel railroad bridge. The simulated stress time history is carried out by the superposition method incorporating the vertical load with rotation moment obtained from the Hermition interpolation function, and compared with developing stress results from measured maxi mum stress. Through this study, we can estimate the remaining fatigue life from a safety point of view and comparative accuracy.

• International Journal of Reliability and Applications
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• 제18권2호
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• pp.21-44
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• 2017

Accelerated life tests (ALTs) are frequently used in manufacturing industries to evaluate the reliability of products within a reasonable amount of time and cost. Test units are subjected to elevated stresses which yield quick failures. Most of the previous works on designing ALT plans are focused on tests that involve a single stress. Many times more than one stress factor influence the product's functioning. This paper deals with the design of optimum modified ramp-stress ALT plan for Burr type XII distribution with Type-I censoring under two stress factors, viz., voltage and switching rate each at two levels- low and high. It is assumed that usage time to failure is power law function of switching rate, and voltage increases linearly with time according to modified ramp-stress scheme. The cumulative exposure model is used to incorporate the effect of changing stresses. The optimum plan is devised using D-optimality criterion wherein the ${\log}_{10}$ of the determinant of Fisher information matrix is maximized. The method developed has been explained using a numerical example and sensitivity carried out.

• 대한기계학회논문집A
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• 제24권1호
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• pp.156-162
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• 2000

Sensitized STS 304 stainless steel crack growth rate(CGR) in high temperature water was investigated under trapezoidal wave loading test using fracture mechanics techniques. The CGR, due to stress corrosion cracking(SCC), were systematically measured as a function of the stress intensity factor and stress. holding time under trapezoidal wave loading. In high temperature water, CGR was enhanced by a synergistic effects in combination with an aggressive environment and mechanical damage. The CGR, $(da/dN)_{env}$ was basically described as a summation of the environmentally assisted crack growth rate $(da/dN)_{SCC}$, $(da/dN)_{CF}$ and fatigue crack growth rate in air $(da/dN)air,. The CGR, $(da/dN)_{env}$, increased linearly with increasing stress holding time. The CGR, $(da/dN)_{SCC}$ decreased linearly with increasing stress holding time. Fracture surface mode varied from trans-granular cracking to inter-granular cracking with increasing stress holding time.

• Child Health Nursing Research
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• 제11권4호
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• pp.415-426
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• 2005

Purpose: The purpose of this study was to identify relations among the parenting stress, maternal sensitivity to infant cues, parenting environment of first-time mothers. Method: The participants were 194 first-time mothers of babies aged 1-6 months who visited well-baby clinics in 5 hospitals. The data were collected from April 15 to June 15, 2003. Results: The parenting stress level was moderate with a mean score of 2.4(range 1-5). The parent domain and parent-child relationship domain of the parenting stress scale were significantly correlated with maternal sensitivity to infant feeding cues (r=-.178, p<.05; r=-.197, p<.01). Parenting stress was significantly correlated with childrearing environment(r=-2.19, p<.01). Parenting stress and childrearing environment were significantly different according to the educational level of the mothers and their prenatal care. Conclusions: Nursing interventions to reduce parenting stress in first-time mothers are needed to improve maternal sensitivity to infant cues and childrearing environment which foster infant development.