• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.12
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• pp.1366-1374
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• 2009

Anterior cruciate ligament(ACL) of human body experiences a large deformation. May during everyday when large deformation is repeated by various activities such as outdoor activity, ACL easily get damaged. In order to acknowledge the effect of the cyclic large deformation to ACL, the constitutive equations for ACL are derived from experiment data. The concept of the objective stress rate plays a important role wherever large deformation occurs. In order to obtain the objective stress rates the eigenprojection technique is used. A comparison is made for four different cases: Jaumann rate, Green-Naghdi rate, logarithmic rate and twirl tensor of Eulerian triad rate for an isotropic material subject to cyclic deformation, such as simple shear motion. Four different materials are studied to compare the behavior of the materials for ACL using different objective rates. Finally, more complicated model with fibers for soft tissues is used to calculate the behavior subjected to cyclic large deformation.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.497-502
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• 2004

This paper presents applications of the objective stress rates to stress update algorithms for transient shell dynamic analysis within the context of explicit time integration. The hypo elasto-plastic materials are assumed in establishing constitutive equations. The derivation of the objective stress rates are investigated by use of the Lie derivative. Comparison results are given between the Kirchhoff and Cauchy stress formulation. The Jacobian determination algorithm proposed in this paper is presented in association with the Belytschko-Lin-Tsay shell theory. Several numerical examples are demonstrated including contact and non-contact examples, by which proposed algorithms are compared with respect to the accuracy and effectiveness.

• Animal Bioscience
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• v.37 no.6
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• pp.1121-1129
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• 2024

Objective: Objective of the study was to reduce heat stress in Murrah buffaloes and maintain their milk production and other vital functions during heat stress. Methods: A total of 21 dyads of calf-mother Murrah buffalo were selected for the study and equally divided in 3 treatment groups. First treatment group was restricted calf contact (RCC), second treatment group was fence line calf contact (FCC) and third treatment groups fence line calf contact and heat stress protection (FCC-HSP [time-controlled fan-fogger system] in the shed). Present study was conducted from April to mid-September 2021. Results: Maximum temperature and temperature humidity index in FCC-HSP shed were significantly (p<0.05) lower than that in FCC and RCC shed. Higher (p<0.05) mean daily milk yield in both the treatment groups FCC (10.36±0.30) and FCC-HSP (10.97±0.31) than RCC (8.29±0.41) was recorded. Though no significant difference between FCC and FCC-HSP in daily milk yield but FCC-HSP yielded 600 gm more milk than FCC. Pulse rate (PR) and respiration rate (RR) were lowest in FCC-HSP followed by FCC and RCC, respectively. Cortisol and prolactin levels were lower (p<0.05) in FCC-HSP followed by FCC and RCC, respectively. Conclusion: Hence, FCC along with heat stress ameliorative measures helped the buffaloes to be free of stress and maintain milk yield during heat stress period of the year in tropical conditions.

• Animal Bioscience
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• v.37 no.1
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• pp.16-27
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• 2024

Objective: The objective of this study was to investigate the effect of heat stress on the growth traits and genetic parameters of Thai native chickens. Methods: A total of 16,487 records for growth traits of Thai native chickens between 2017 and 2022 were used in this study. Data included the body weight at birth, body weight at 4, 8, and 12 weeks of age (BW0, BW4, BW8, BW12), average daily gain during 0 to 4, 4 to 8, and 8 to 12 weeks of age (ADG0-4, ADG4-8, ADG8-12), absolute growth rate at birth, at 4, 8, and 12 weeks of age (AGR0, AGR4, AGR8, AGR12). The repeatability test day model used the reaction-norm procedure to analyze the threshold point of heat stress, rate of decline of growth traits, and genetic parameters. Results: At temperature and humidity index (THI) of 76, Thai native chickens began to lose their growth traits, which was the onset of heat stress in this study. The estimated heritability, genetic correlation between animal and heat stress effect, and correlations between the intercept and slope of the permanent environmental effects were 0.27, -0.85, and -0.83 for BW, 0.17, -0.81, and -0.95 for ADG, 0.25, -0.61, and -0.83 for AGR, respectively. Male chickens are more affected by heat stress than female chickens with a greater reduction of BW, ADG, and AGR, values equal to -9.30, -0.23, -15.21 (in males) and -6.04, -0.21, -10.10 (in females) gram per 1 level increase of THI from the THI of 76. Conclusion: The influence of thermal stress had a strong effect on the decline in growth traits and genetic parameters in Thai native chickens. This study indicated that genetic models used in conjunction with THI data are an effective method for the analysis and assessment of the effects of heat stress on the growth traits and genetics of native chickens.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.19 no.1
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• pp.35-45
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• 2015

Objective The aim of this study was to investigate stress-related factors. Method: The subjects were 22,937 persons who had received health examination by Korean Medicine and submitted questionnaires for 8 months from March to November in 2011. The stress was measured by heart rate variability in an automobile manufacturing industry. We analyzed the relationship between stress and other factors including ages, smoke amount, drinking frequency, exercise frequency, occupational category, conjugal condition by multivariate analysis with SPSS ver. 19.0. Results: Comparing "normal" to "very bad" and "bad" level of stress, ages, drinking frequency, conjugal condition are not significant difference(p>0.05). But smoking amount and occupational category are significant difference(p<0.05). Whereas comparing "normal" to "very good" and "good" level of stress, ages, occupational category, conjugal condition, smoking amount, drinking frequency are not significant difference(p>0.05). Exercise is significant difference(p<0.05). Conclusion: The results of this study suggest that smoke is affected to stress negatively, whereas exercise is affected to stress positively.

• Journal of Oriental Neuropsychiatry
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• v.18 no.1
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• pp.111-122
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• 2007

Objective : Progressive muscle relaxation(PMR) therapy is the way of mind and body self-regulation which makes major muscles tension to be comfortable condition. It was considered to be important to check the level of relaxation in objective validity. Therefore, Heart rate variability(HRV) is the valuable measurement to investigate the effect of progressive muscle relaxation therapy on autonomic nerve system. Method : I studied 38 subjects. The subjects were measured HRV at first. And then, Using a CD player, the subjects listened to recorded PMR program for 15 minutes. After this progress, I rechecked HRV. Results : heart rate item of HRV was significantly decreased. Also, the numerical value of SDNN(standard deviation of all NN intervals) and SDSD(standard deviation of differences between adjacent NN intervals) items of HRV were showed significantly increased in all subjects after PMR. Conclusion : It indicated that PMR is efficient for inspiring resistance of the stress and a sense of stability, and PMR is a valuable method to reduce the mind stress and stiffness of body muscle.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.1
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• pp.69-81
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• 2019

Objective: The purpose of this study was to find out what kind of change in death rate when job stress is solved by calculating job stress relieve coefficient. Methods: This study used the data of the fourth working condition survey. Regression analysis was used to determine the relationship between health effects recognition and Death rate per 10,000 workers. After that the recognizing and non - recognizing groups were categorized by health effects recognition, and the differences between the two groups were confirmed by cross tabulation analysis. Results: Regress analysis P-value is 0.011 and $R^2$ is 0.979. Death rate per 10,000 worker increased with the increase in the number of non - health impact recognizing group. The relieve factors were (1) work culture(2.859) (2) physical environment(2.184), (3) improper reward (1,839), (4) relationship conflict(1.646), (5) job requirement(1.613), (6) job autonomy(1.354), (7) job instability(1.334), And (8) organizational system(1.201). The higher the relieve coefficient is, the higher the probability of belonging to the non - health impact recognizing group when there is no job stress factor. Conclusions: When job stress is resolved, there is a high probability that the health impact recognition is reduced, which can lead to an increase in death rate. but according to previous studies, Job stress can cause accidents by reducing the safety behavior of accidents. The job stress management plan should simultaneously consider reducing job stress and increasing health impact recognition.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.2
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• pp.263-269
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• 2018

Objective: Heat stress (HS) triggers oxidative stress and respiratory alkalosis in pigs. The objective of this experiment was to study whether a short-term supranutritional amount of dietary vitamin E (VE) can mitigate oxidative stress and respiratory alkalosis in heat-stressed pigs. Methods: A total of 24 pigs were given either a control diet (17 IU/kg VE) or a high VE (200 IU/kg VE; HiVE) diet for 14 d, then exposed to thermoneutral (TN; $20^{\circ}C$, 45% humidity) or HS ($35^{\circ}C$, 35% to 45% humidity, 8 h daily) conditions for 7 d. Respiration rate and rectal temperature were measured three times daily during the thermal exposure. Blood gas variables and oxidative stress markers were studied in blood samples collected on d 7. Results: Although HiVE diet did not affect the elevated rectal temperature or respiration rate observed during HS, it alleviated (all p<0.05 for diet${\times}$temperature) the loss of blood $CO_2$ partial pressure and bicarbonate, as well as the increase in blood pH in the heat-stressed pigs. The HS reduced (p = 0.003) plasma biological antioxidant potential (BAP) and tended to increase (p = 0.067) advanced oxidized protein products (AOPP) in the heat-stressed pigs, suggesting HS triggers oxidative stress. The HiVE diet did not affect plasma BAP or AOPP. Only under TN conditions the HiVE diet reduced the plasma reactive oxygen metabolites (p<0.05 for diet${\times}$temperature). Conclusion: A short-term supplementation with 200 IU/kg VE partially alleviated respiratory alkalosis but did not reduce oxidative stress in heat-stressed pigs.

• Physical Therapy Rehabilitation Science
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• v.13 no.1
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• pp.134-142
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• 2024

Objective: This study aimed to compare the subjective health status, physical activity index, and perceived stress rate of obese children with those of healthy children through propensity matching analysis and to use the results to help manage obese children. Design: Descriptive correlation study. Methods: This study conducted a secondary analysis using raw data from the National Health and Nutrition Examination Survey. Propensity matching (1:2) was conducted between obese and healthy adolescents. Results: The number of days of physical activity was 1.22 days for the obese adolescent group and 1.01 days for the non-obese adolescent group, which was higher in the obese group (p=0.003). The subjective health status was 3.43 and 3.81 in the obese and non-obese adolescent groups, respectively, showing a higher difference in the normal group (p<0.001). No statistical difference was observed in the perceived stress rate (p=0.871) or strength exercises (p=0.190) between the two groups. Conclusion: This study suggests the need for development measures to effectively improve youth physical activity, muscle-strengthening programs, stress management, and subjective health status in obese and normal groups.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.349-352
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• 2006

The plastic deformation of polycrystalline materials is induced by changes of the microstructure when the loading is beyond the critical state of stress. Constitutive models for the crystal plasticity have the common objective which relates microscopic single crystals in the crystallographic texture to the macroscopic continuum point. In this paper, a new consistent tangent stiffness for the anisotropic elasto-viscoplastic analysis of polycrystalline deformation is developed, which can be used in the finite element analysis for the slip-dominated large deformation of polycrystalline materials. In order to calculate the consistent tangent stiffness, the state function is defined based on the consistency condition between the elastic and plastic stress. The rate of shearing increment($\Delta{\gamma}^{\alpha}$) is calculated with satisfying the consistency condition. The consistency condition becomes zero when the trial resolved shear stress($\tau^{{\alpha}^*}$) becomes resolved shear stress($\tau^{\alpha}$) at every step. Iterative method is utilized to calculate the rate of shearing increment based on the implicit backward Euler method. The consistent tangent stiffness can be formulated by differentiating the rate of shearing increment with total strain increment after the instant rate of shearing increment converges. The proposed tangent stiffness is applied to the ABAQUS/Standard by implementing in the ABAQUS/UMAT.