• BioChip Journal
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• v.12 no.4
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• pp.294-303
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• 2018

Shear stress occurs in flowing liquids, especially at the interface of a flowing liquid and a stationary solid phase. Thus, it occurs inside the artery system of the human body, where it is responsible for a number of biological functions. The shear stress level generally remains less than $70dyne/cm^2$ in the whole circulatory system, but in the stenotic arteries, which are constricted by 95%, a shear stress greater than $1,000dyne/cm^2$ can be reached. Methods of researching the effects of shear stress on cells are of large interest to understand these processes. Here, we show the development of a microfluidic device for generating shear stress gradients. The performance of the shear stress gradient generator was theoretically simulated prior to experiments. Through simple manipulations of the liquid flow, the shape and magnitude of the shear stress gradients can be manipulated. Our microfluidic device consisted of five portions divided by arrays of micropillars. The generated shear stress gradient has five distinct levels at 8.38, 6.55, 4.42, 2.97, and $2.24dyne/cm^2$. Thereafter, an application of the microfluidic device was demonstrated testing the effect of shear stress on human umbilical vein endothelial cells.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.3
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• pp.163-172
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• 2020

Purpose : The purpose of this study was to investigate economic anxiety, self-efficacy, and financial stress levels in middle-aged male and identify factors affecting financial stress and provide baseline data for the development of nursing interventions to reduce financial stress in middle-aged male. Methods : Participants were 91 middle-aged male who live in Seoul and Gyeonggi Province. The data collection period was from April 1, 2020, to May 1. In this study, the questionnaire of economic anxiety, self-efficiency, financial stress was used. The data were analyzed by average, standard deviation, minimum, maximum correlation and regression using SPSS version 21.0. Results : In this study, the financial stress of middle-aged male affected economic anxiety with significant results (β=.628, p<.001). The absolute model's explanatory power was 36.8 % (adjusted R2=.368), indicating that economic anxiety affects financial stress levels in middle-aged male (F=27.151, p<.001). Conclusion : This study shows that economic anxiety affects financial stress. Based on the research results, basic data for the development and application of nursing programs to reduce financial stress were presented in consideration of the economic anxiety of middle-aged males. Therefore, there is a need for mediation to help middle-aged men positively recognize real-life situations and changes in society. Such mediation involves the development and application of educational and counseling programs that can reduce financial stress and economic anxiety in middle-aged men.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.22 no.4
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• pp.236-245
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• 2011

Objectives : The objective of this study was to evaluate the relationship of the parenting stress with their children's characteristics for typically developing preschool children. Methods : Parents of 38 preschool children (mean age : 4.4${\pm}$0.7 years, 22 boys) completed the Korean Parenting Stress Index, the Korean Child Behavior Checklist, the Conners Parent and Teacher Rating Scale-Abbreviated form (CPRS and CTRS), the Junior Temperament and Character Inventory, the Children's Sleep Habit Questionnaire and the Social Responsiveness Scale. All 38 children performed the Comprehensive Attention Test (CAT). Results : The children's inattentive and hyperactive problems, as measured by the CBCL, CPRS and CAT, had positive correlation with parenting stress. Both internalizing and externalizing behavioral problems were associated with parenting stress. Of the child's temperament dimensions, Novelty Seeking and Harm Avoidance were positively correlated with parenting stress, but Persistence and Cooperativeness were negatively correlated with parenting stress. Sleep anxiety and other sleep characteristics showed a correlation with parenting stress. Social Motivation and Communication were also positively related to parenting stress. Conclusion : Our results suggest that parenting stress could be related to the children's cognition, emotion, behavioral characteristics, sleep habits and social development. These results could assist in the development of interventions to improve the parental well-being in typically developing preschool children.

• Journal of Families and Better Life
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• v.29 no.4
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• pp.217-232
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• 2011

The main purpose of this study was to examine the mediating roles of mothers' psychological well-being and support/control in the relationship between maternal child-related stress and adolescents' school adjustment. Participants were 389 3rd grade middle school students and their mothers. Mothers completed questionnaires about child-related stress and psychological well-being. Adolescents completed scales of maternal controlling/supportive parenting and school adjustment. Results indicated that a direct effect of mothers' child-related stress on adolescents' school adjustment was not significant. However, mothers' psychological well-being and support/control mediated the relations between child-related stress and adolescents' school adjustment. A higher level of child-related stress in mothers was associated with a lower level of psychological well-being, followed by a lower level of adolescents' school adjustment. Mothers who reported a higher level of child-related stress tended to be less supportive and more controlling, which led to a lower level of school adjustment. These findings suggest the need for considering both maternal characteristics and parenting in explaining adolescents' school adjustment.

• Physical Therapy Korea
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• v.5 no.2
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• pp.65-80
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• 1998

Parents of handicapped children are experiencing difficulties in their children's care, social isolation, change of life style and lirnited leisure time. Because the parents should take care of the children's daily life, they have lots of psychological and physical stress. Chronic stress of parents puts stress to the other family members and affects the development of children with handicap. The purpose of this study were to identify the level of stress in each of parents of children with motor problem, the characteristics of the children and general information related with the children, and to analyse the stress by reasons. Specially organized questionnaire were used for an investigation method. "Test of stress in mother who has children with chronic illness" by Kim Hee-soon were modified and used. The questionnaire answered by 43 mothers and 35 fathers were analyzed. Data analysis includes frequency analysis, Pearson correlation coefficients, paired-samples t-test and MANOV A by SPSSWIN. The results were as follows: 1) Degree of handicap was most moderate (46.5%), level of motor development was most pull to walk (34.9%), and combined handicap was 69.8%. 2) Sexual distribution represented that 51.2% male and 48.8% female. The cost of physical therapy was 69.8% in no more than 100,000 won. 3) The mean of age, for the mother was 32.8 years and 35.3 years. Level of motor development that mother and father expect was 88.4%, 83% walk alone. 4) Both mother and father experienced stress in other of Part II (changes in father was the illness status of the child and difficulty in taking care of child), Part III (prognosis of the child's condition), Part I (social-personal relationships and the responsibility of the care givers). In the total score of stress, mother's stress is indicated higher level than father's stress. 5) There was no correlationship between characteristics and stress of mother and father. 6) There was no statistically significant difference between characteristics and related general information of children with handicap and stress of mother and father. As a results, the mother of children with handicap are experiencing more stress than the father. Both of parents have the most difficulties in the changes in the illness status of the child and difficulty in taking care of child. This study can be used as resources of education, therapy and counselling for children with handicap and their parents. This study, also, can be used to encourage the quality of Iife for the children with handicapped and their family.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.844-852
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• 2014

PBX simulant is known to exhibit highly nonlinear behaviors of deformation such as the stress softening, hysteresis under cyclic loading, residual strain after unloading, and aging. This paper proposes a new pseudo-elastic model for PBX simulant considering stress softening and residual strain. Uniaxial loading and unloading tests at quasi-static states were carried out in order to obtain the mechanical properties of the PBX simulants. And then the Dorfmann-Ogden model is modified to make it consistent with the test result of PBX simulants. Prediction with the new model shows a good correspondence to the experimental data demonstrating that the model properly describes stress softening and residual strain of PBX simulants.

• Plant Biotechnology Reports
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• v.4 no.4
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• pp.243-251
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• 2010

Nitric oxide (NO) has been shown to be involved in diverse physiological processes in microbes, animals and plants. In this study, the involvement of NO in the development and possible roles in oxidative stress protection of Chinese cabbage (Brassica rapa subsp. pekinensis cv. Samrack-ulgari) seedlings were investigated. Exogenous application of sodium nitroprusside (SNP) retarded root elongation, while increasing lateral root formation of Chinese cabbage. Plants showed no signs of external stress due to SNP application in true leaves. Cotyledons of 3-week-old Chinese cabbage plants were found to be highly sensitive to SNP application. Treated cotyledons displayed rapid tissue collapse and associated cell death. Although SNP application reduced root growth under normal growth conditions, it also enhanced methyl viologen (MV)-mediated oxidative stress tolerance. Analysis of SNP application to Chinese cabbage leaf disks, revealed SNP-induced tolerance against oxidative stresses by MV and $H_2O_2$, and evidence includes prevention of chlorophyll loss, superoxide anion (${O_2}^-$) accumulation and lipid peroxidation. This report supports a role for nitric oxide in modulating early seedling development, programmed cell death and stress tolerance in Chinese cabbage.

• Journal of Plant Biotechnology
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• v.38 no.3
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• pp.215-220
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• 2011

This study was conducted to investigate how to enhance resistance to oxidative stress in petunia progeny obtained by a crossing between transgenic plants, MnSOD (SOD2) ($T_4$) and NDPK2 ($T_2$), to develop transgenic petunia much more resistant to environmental stress. At the treatment of MV 200 ${\mu}M$, the progeny was significantly less damaged than its parental plants (SOD2- or NDPK2-transgenic lines) as well as wild type plants, implying its resistance to oxidative stress was enhanced compare to that of SOD2- or NDPK2- transgenic plants. In an expression of 11 quantitative traits, the progeny remained similar to control plants, although it infrequently displayed slightly longer or wider than either parental or wild type plants. In the expression of 6 qualitative traits, there was no significant difference between parental or non-transgenic control plants.

• Journal of Korean Academy of Nursing Administration
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• v.7 no.2
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• pp.349-359
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• 2001

This study was attempted to provide the basic data concerning development of stress management program for hospital nurses, and to focused on the analysis of job stress and social support according to the types of behavior pattern. The subjects were 296 staff nurses at a general hospital in Seoul. Data were collected with self-reported questionnaires and analyzed by SPSS-PC+ 8.0 win for descriptive analysis and ANOVA analysis. The results of this study indicated that; 1) The perceived job stress was negatively correlated with social support and was positively correlated with TABP. 2) The score of the perceived job stress was higher in TABP nurses than TBBP. The TABP nurses usually perceived more support from peers than from supervisors These results showed that the staff nurses who supported from supervisor felt less stress, and the score of the perceived job stress was higher in TABP nurses than in TBBP. So the differences in social support and job stress according to the types of behavior pattern must be considered significantly in development of the staff nurses' stress management program. Also it was needed to develop the strategies that TABP nurses was effectively supported by the supervisor.

• Restorative Dentistry and Endodontics
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• v.25 no.1
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• pp.91-108
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• 2000

Most of cervical abrasion and erosion lesions show gingival margin where the cavosurface angle is on cementum or dentin. Composite resin restoration of cervical lesion shrink toward enamel margin due to polymerization contraction. This shrinkage has clinical problem such as microleakage and secondary caries. Several methods to diminish contraction stress of composite resin restoration, such as modifying cavity form and building up restorations in several increments have been attempted. The purpose of this study was to compare polymerization contraction stress of composite resin in Class V cavity subjected to cavity forms and placement methods. In this study, finite element model of 5 types of Class V cavity was developed on computer tomogram of maxillary central incisor. The types are : 1) Box cavity 2) Box cavity with incisal bevel 3) V shape cavity 4) V shape cavity with incisal bevel 5) Saucer shape cavity. The placement methods are 1) Incisal first oblique incremental curing 2) Bulk curing. An FEM based program for light activated polymerization is not available. For simulation of curing dynamics, time dependent transient thermal conduction analysis was conducted on each cavity and each placement method. For simulation of polymerization shrinkage, thermal stress analysis was performed with each cavity and each placement method. The time-temperature dependent volume shrinkage rate, elastic modulus, and Poisson's ratio were determined in thermal conduction data. The results were as follows : 1. With all five Class V cavifies, the highest Von Mises stress at the composite-tooth interface occurred at gingival margin. 2. With box cavity, V shape cavity and saucer cavity, Von Mises stress at gingival margin of V shape cavity was lower than the others. And that of box cavity was lower than that of saucer cavity. 3. Preparing bevel at incisal cavosurface margin decreased the rate of stress development in early polymerization stage. 4. Preparing bevel at incisal cavosurface margin of V shape cavity increased the Von Mises stress at gingival margin, but decreased at incisal margin. 5. At incisal margin, stress development by bulk curing method was rapid at early stage. Stress development by first increment of incremental curing method was also rapid but lower than that by bulk curing method, however after second increment curing final stress was the same for two placement methods. 6. At gingival margin, stress development by incremental curing method was suddenly rapid at early stage of second increment curing, but final stress was the same for two placement methods.