• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.65-70
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• 2001

In this study, CT specimens were prepared from spring steel(SUP9) processed shot peening which was room temperature, low temperature and high temperature experiment. And we got the following characteristics from fatigue crack growth test carried out in the environment of room, low temperature and high temperature at $25^{\circ}C$, -3$0^{\circ}C$, -5$0^{\circ}C$, -7$0^{\circ}C$, -10$0^{\circ}C$ and 5$0^{\circ}C$, 10$0^{\circ}C$ , 15$0^{\circ}C$, 18$0^{\circ}C$ and in the range of stress ratio of 0.05 by means of opening mode displacement. The threshold stress intensity factor range $\DeltaK_{th}$ in the early stage of fatigue crack growth (Region I ) and stress intensity factor range ΔK in the stable of fatigue crack growth (Region II) was decreased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature and high temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.5
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• pp.651-661
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• 2008

The mother's obesity-related stress and it's association with obesity, food intake, and physical activity in both mothers and their children were determined. Based on self-reports from 470 mothers, obesity stress of mothers were scored by using a five-point Likert scale; only low and high stress scores were used in this study. The perceptions of mothers' weights and their children's weights, mothers' Body Mass Indices (BMI), and preschoolers' Weight-Length Indices (WLI)(%) were also determined. The obesity stress of mothers was significantly associated with the mothers' BMI (high stress: $23.5{\pm}2.4$ vs. low stress: $19.6{\pm}1.7$, p<0.05), but not with their children's obesity. Mothers with a high obesity stress reported a higher percentage of family history of obesity (62.1% vs. 38.3%, p<0.001) than mothers with low obesity stress. Compared to mothers with low obesity stress, mothers with high stress had lower correct-perceptions about their weights (p<0.05) but higher correct-perceptions for their children's weights. Almost 54.5% of mothers with high stress reported watching television 2 or more extra hours per day, compared with 32.2% of mothers with low stress (p<0.05). More children of mothers with high stress had long hours of daily TV viewing than children of mothers with low stress (36.0% vs. 15.3%, $X^2=10.491$, p<0.05). Mothers with high stress reported lower intake of protein-rich foods (p=0.01) and vegetables (p=0.039), but a higher intake of snacks (p=0.009), compared to mothers with low stress. More children of mothers with high stress reported eating high fat snacks or high sugar snacks everyday, but this was not statistically significant. In conclusion, high obesity stress in mothers were greatly associated with their BMI and their inactive life style, including long TV viewing hours per day and unbalanced food intakes, which can lead their children becoming inactive and obese. Special attention is recommended for overstressed mothers and their children, especially those who enjoy long hours of TV viewing.

• Journal of Animal Science and Technology
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• v.60 no.4
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• pp.7.1-7.5
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• 2018

Background: Mice are widely accepted research models of great clinical significance. Maintenance of laboratory mice breed is an essential aspect for performing research activities in various fields of science. Infanticide is one of the prominent causes of litter loss during maintenance of laboratory mice stock. The present study is an effort to monitor the effect of change in ambient temperature of female mice below the normal range on cannibalism and infanticide during early postparturition phase. Adult female Swiss albino mice have been divided into two groups of control and treatment. On the day of litter group one was maintained under controlled temperature conditions (minimum $20^{\circ}C$ to maximum $23^{\circ}C$) throughout, while female mice belong to group two have been exposed to variation of room temperature (maximum $15^{\circ}C$ to minimum $10^{\circ}C$ for two nights and one day) until 36 h postparturition. Results: The effects of temperature changes were observed on the infanticide behaviour of dams along with the survival of pups in early postparturition phase till 36 h after delivery. The significant statistical difference (P < 0.05) was reported in infanticide behaviour of dams when control and treatment group was compared. It is observed that decrement in surrounding temperature promotes decrement in the ambient body temperature of dams during early postparturition. It is proposed that alteration of hypothalamic homeostasis due to temperature change induces cannibalism and infanticide behaviour. Lack of thermoregulation during early postparturition creates the sense of insecurity, in-satiety, anxiety and stress. Conclusions: Authors strongly recommend the maintenance of body and surrounding temperature to prevent infanticidal behaviour and cannibalism within Swiss albino mice population. Further investigations are advisable to authenticate the active behavioural and biochemical pathway behind the phenomena.

• Journal of the Korean society of biological therapies in psychiatry
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• v.24 no.3
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• pp.230-238
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• 2018

Objectives : Among adolescents, the proportion of daily smoking tends to increase with age, and does not return to the previous level. Therefore, we examined the factors associated with smoking frequency in a nationwide sample of Korean adolescents to help prevent the progression of smoking. Methods : Among 127,804 adolescents who participated in the 2016 and 2017 Korean Youth Risk Behavior Web-Based Survey, data from 7,781 adolescents who replied that they currently smoked were analyzed. According to the frequency of cigarette smoking, participants were classified into daily and non-daily smokers. Participants' socio-demographic characteristics, smoking behavior, and psychological problems including perceived stress, depressive mood, and suicidality were assessed. Results : There were 3,627(47.4%) daily smokers and 4,154(52.6%) non-daily smokers. Low parental educational level, and early smoking experience were positively associated with daily smoking. High academic achievement, and high socio-economic status were negatively associated with daily smoking. Daily smoking was positively associated with lower happiness, lower sleep satisfaction, and severe stress during the past 12 months. Factors affecting suicide attempts of smokers were sex, residential type, socioeconomic status, and early smoking experience. Conclusion : The results indicated that socially disadvantaged families, and smoking experience with young age influenced daily smoking among Korean adolescents. Daily smoking was associated with psychological problems including lower happiness, lower sleep satisfaction, and severe stress. Early smoking experience influenced suicidal attempts among Korean adolescent smokers. Early intervention for smoking cessation in this high-risk group may contribute to prevention of these psychiatric complications of smoking.

• Journal of Korean Biological Nursing Science
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• v.21 no.3
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• pp.178-187
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• 2019

Purpose: The purpose of this study was to investigate how college students' perceived stress, cognitive stress, and somatization affect their heart rate variability (HRV). Methods: This study is a cross-sectional survey research on 191 university students, registered at the G University. The perceived stress scale (PSS) and cognitive stress response scale, were used to assess level of stress. The somatization symptom scale of the Symptom Check List 90 (SCL-90), was used to assess level of somatization caused by stress. To assess heart rate variability (HRV), we conducted a five-minute test using a pulse wave analyzer, to analyze short-term HRV. Results: The SCL-90 somatization score had relatively high positive correlation (p< .001) with cognitive stress, but low positive correlation (p< .001) with perceived stress. Cognitive stress response had low negative correlation (p< .001) with 1nSDNN and 1nRMSSD among HRV parameters. Perceived stress was not correlated with HRV. Multiple regression analysis showed that variables of perceived stress, cognitive stress, and somatization symptoms, could not explain HRV. By contrast, one of the HRV indicators, 1nSDNN, was affected by age, gender, and aggressive-hostile thought, the latter being a subscale of the cognitive stress response scale. Conclusion: This study suggests that stress evaluation for people in early adulthood will be more effective, if the evaluation examines cognitive stress and heart rate variability.

• The Korean Journal of Ecology
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• v.19 no.2
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• pp.151-163
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• 1996

To investigate the early symptoms of light-chilling, alterations of chlorophyll fluorescence transients were monitored in cucumber (Cucumis sativus L. cv. Ilmichungjang) leaves. During 24 h chilling, decreases in (Fv)m/Fm, qE and qQ, and an increase in Fo were observed. The chilling effects were not recovered at room temperature, and a significant increase in Fo was observed during the recovery period. After 6 h chilling, ‘dip’(D) level of the transients became obscure, and the negative slope after ‘peak’(P) disappeared. The first derivative (dFv/dt) of the fast fluorescence rise curve was used to obtain more accurate information about the changes in the transients. The maximal rate of the fluorescence increase in the D-p rise curve (Fr) has been the most frequently used chilling stress indicator. However, a correct value of Fr could not be measured when the D level became obscure. This problem was overcome by introducing a new indicator, HFr (dFv/dt at Fv = 1/2 (Fv)m), and HFr gave very similar values to Fr. To monitor the changes in curvature around D level, another new parameter, ${\Delta}S$(D-Fr), was also introduced. These three parameters decreased very sensitively during light-chilling. In addition, increases in these parameters were observed during the first 2 h chilling, but this increase in Fr was also observed in pea leaf discs dark-chilled for 15 min, suggesting that this very early change is a common response to chilling in both pea and cucumber leaves. Quenching coefficients were also very sensitive to chilling, especially qE. Discussion on the usage of these parameters as chilling stress indicators is given in the text.

• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.61-70
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• 1996

In cementless total hip arthroplasty(THA), an initial stability of the femoral component is mandatory to achieve bony inyowth and secondary long term fixation. Primary stability of the femoral component can be obtained by minimizing the magnitude of relative micromotions at bone stem interface. An accurate evaluation of interf'ace micromotion and stress/strain fields in the bone-implant system may be relevant for better understanding of clinical situations and improving THA design. Recently finite element method(FEM) was introduced in'orthopaedic research field due to its unique capacity to evaluate stress in structure of complex shape, loading and material behavior. The authors developed the 3-dimensional finite element model of proximal femur with $Multilock^{TM}$ stem of 1179 blick elements to analyse the micromotions and mechanical behaviors at the bone-stem inteface in early post-operative period for the load simulating single leg stance. The results indicates that the values of relative motion for this well fit stem were $150{\mu}m$ in maximum $82{\mu}m$ in minimum and the largest relative motion was developed in medial region of Proximal femur and in anterior-posterior direction. The motion in the proximal bone was much greater than in the distal bone and the stress pattern showed high stress concentration on the cortex near the tip of the stem. These findings indicate that the loading on the hip joint in the early postoperative situation before achieving bony ingrowth could produce large micromotion of $150{\mu}m$ and clinicaly non-cemented THA patient should not be allowed weight bearing strictly early in the postoperative period.

• Journal of dental hygiene science
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• v.19 no.3
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• pp.198-204
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• 2019

Background: Oxidative stress is a known to be associated with in the pathogenesis of many inflammatory diseases, including periodontitis. Ursolic acid is a pentacyclic triterpenoid with has antimicrobial, antioxidative, and anticancer properties. However, the role of ursolic acid in the regulating of osteogenesis remains undetermined. This study was aimed to elucidate the crucial osteogenic effects of ursolic acid and its ability to inhibit oxidative stress by targeting the immediate early response 3 (IER3)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Methods: Cell proliferation was determined using water-soluble tetrazolium salt assay, cell differentiation was evaluated by alkaline phosphatase (ALP) activity, and formation of calcium nodules was detected using alizarin red S stain. Generation of reactive oxygen species (ROS) was determined using by DCFH-DA fluorescence dye in hydrogen peroxide ($H_2O_2$)-treated MG-63 cells. Expression levels of IER3, Nrf2, and heme oxygenase-1 (HO-1) were analyzed using western blot analysis. Results: Our results showed that ursolic acid up-regulated the proliferation of osteoblasts without any cytotoxic effects, and promoted ALP activity and mineralization. $H_2O_2$-induced ROS generation was found to be significantly inhibited on treatment with ursolic acid. Furthermore, in $H_2O_2$-treated cells, the expression of the early response genes: IER3, Nrf2, and Nrf2-related phase II enzyme (HO-1) was enhanced in the presence of ursolic acid. Conclusion: The key findings of the present study elucidate the protective effects of ursolic acid against oxidative stress conditions in osteoblasts via the IER3/Nrf2 pathway. Thus, ursolic acid may be developed as a preventative and therapeutic agent for mineral homeostasis and inflammatory diseases caused due to oxidative injury.

• Journal of Preventive Medicine and Public Health
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• v.56 no.5
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• pp.413-421
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• 2023

Objectives: This study explored the effect of the coronavirus disease 2019 (COVID-19) pandemic on psychosocial stress in prime working-age individuals in Korea, focusing on gender inequalities. We hypothesized that the impact of COVID-19 on mental health would differ by age and gender, with younger women potentially demonstrating heightened vulnerability relative to men. Methods: The study involved data from the Korea Community Health Survey and included 319 592 adults aged 30 years to 49 years. We employed log-binomial regression analysis, controlling for variables including age, education, employment status, marital status, and the presence of children. The study period included 3 phases: the period prior to the COVID-19 outbreak (pre-COVID-19), the early pandemic, and the period following the introduction of vaccinations (post-vaccination). Results: The findings indicated that women were at a heightened risk of psychosocial stress during the early pandemic (relative risk [RR], 1.01; 95% confidence interval [CI], 0.98 to 1.05) and post-vaccination period (RR, 1.07; 95% CI, 1.04 to 1.10) compared to men. This pattern was prominent in urban women aged 30-34 years (pre-COVID-19: RR, 1.06; 95% CI, 1.02 to 1.10; early pandemic: RR, 1.16; 95% CI, 1.08 to 1.25; post-vaccination period, RR, 1.22; 95% CI, 1.14 to 1.31). Conclusions: The COVID-19 pandemic has exerted unequal impacts on psychosocial stress among prime working-age individuals in Korea, with women, particularly those in urban areas, experiencing a heightened risk. The findings highlight the importance of addressing gender-specific needs and implementing appropriate interventions to mitigate the psychosocial consequences of the pandemic.

• Korean Journal of Child Studies
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• v.37 no.4
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• pp.145-158
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• 2016

Objective: This study investigated the moderating effect of emotional dysregulation on the relationship between teacher efficacy and job stress among teachers in the Early Childhood Education and Care (ECEC). Methods: The participants included 586 ECEC teachers from 99 centers in Seoul, Gyeonggi-do, Daejeon, Chungcheong-do, Jeolla-do, and Gyeongsang-do. The data were analyzed through frequencies, percentages, and Pearson's correlations using SPSS 21.0 (IBM Co., Armonk, NY). To analyze the moderating effect, Ping's (1996) two-step approach was used via AMOS 20.0 (IBM Co., Armonk, NY). Results: The main findings are as follows. First, the mean scores of ECEC teacher efficacy and job stress showed above the average, and the mean score of emotional dysregulation was the nearly average. Second, fit statistics indicated that the proposed model, as revised, provided an acceptable fit to the sample data. This proposed model showed that the emotional dysregulation of teachers in ECEC had a moderating effect on the relationship between teacher efficacy and job stress. Conclusion: These findings imply that the ECEC teachers showed the higher level of self-trust and self-confidence than average regarding their own work, and suffered from the work overload. Also, the positive and supportive working environment would help the ECEC teachers to reduce their emotional dysregulation. In addition, there was a moderating effect of the ECEC teachers' emotional dysregulation on the relationship between teacher efficacy and job stress. These findings imply that the workshop or counselling programs need to be provided to teachers in order to help control their emotion dysregulation and reduce their job stress.