• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.1
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• pp.28-35
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• 1983

Quantitative analysis have been carried out on the micro-cracks on the surface and into the depth of unnotched smooth mild steel specimen under cyclic stains by rotating bending fatigue tests. Some of the results are; (1) Cracks initiate at the early stage of fatigue life N$_{I}$/ N$_{f}$=10 to 20%, and propagate during the rest of fatigue life. (2) Coalescence of highly crowded small fatigue cracks of random distribution seems to induce the final fracture at higher stress level. (3) The curves of crack initiation and the equal crack length on the graph of stress versus number of cycles are parallel to the S-N curve. (3) The curves of crack initiation and the equal crack length on the graph of stress versus number of cycles are parallel to the S-N curve. (4) The distributions of micro-surface crack length and depth show the composite Weibull distributions which are approximated to two straight lines separated by the value of transient region between stage I and stage II crack.k.k.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.2
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• pp.15-22
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• 1998

The effects of shot peening an the fatigue strength are studied in this paper. Applying the multistage shot peening on the material. the relation between the residual stress and fatigue strength compressive is investigated. Observing tensile strength elongation. reduction of area. hardness. and roughness. the results can be summarized as follows ; 1.The change of mechanical properties is small before and after the shot peening is carried out. The change of hardness is also small in high hardness material. 2.The surface roughness does not affect the fatigue strength. but the surface roughness is improved by multi-stage shot peening. 3.The fatigue strength of multi-stage shot peening material is 756MPa and is 1.78 times higher than that of un-peened material. 4.The maximum compressive residual strength of multi-stage shot peening material is -792MPa the fatigue strength seems to be improved by residual stress.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.5
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• pp.805-816
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• 2015

In the present study, external restraints imposed normal to the plate during the cooling stage were determined to be effective for reduction of the angular distortion of butt-welded or fillet-welded plate. A welding analysis model under external force during the cooling stage was idealized as a prismatic member subjected to pure bending. The external restraint was represented by vertical force on both sides of the work piece and bending stress forms in the transverse direction. The additional bending stress distribution across the plate thickness was reflected in the improved inherent strain model, and a set of inherent strain charts with different levels of bending stress were newly calculated. From an elastic linear FE analysis using the inherent strain values taken from the chart and comparing them with those from a 3D thermal elasto-plastic FE analysis, welding deformation can be calculated.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.62-62
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• 2022

Among annual precipitation in Korea (1306.3 mm), 54% of it falls intensively in summer, and only about 12.4% falls in April and May, when the water requirement of wheat is the highest. Korean wheat also could be damaged by soil water excess stress as frozen soil thaws after winter (late Feb-Mar). This study was conducted to evaluate effect of soil water stress on yield and quality of Korean wheat cultivar 'Saegeumgang'. Soil water treatments consisted of 4 treatments; water excess treatment in tilling stage (3.23-3.30), drought treatment in ripening stage (Apr-Jun), irrigation treatment in ripening stage (5.10) and standard condition. There was no significant difference between the treatment conditions for culm length, and the number of spike number was the highest in the order of irrigation in the ripening period (951)> standard cultivation (876)> excess water treatment in the tilling stage (752)> drought treatment in the ripening stage (767/m²). Test weight and Thousand grain weight were 548g/L and 22. lg respectively, which were lower than other treatments, and there was no significant difference between the other treatments. Abortive grain was 5.4kg/10a which was lower than other treatment, and there was no significant difference between the other treatment than other treatments. In drought treatment, protein content was 11.9% which is the highest among all treatments, and SDS-sedimentation value was 27.2ml under drought treatment which was very low compared to other treatments. Therefore, wheat yield and spike number were decreased in excess water condition at tilling stage and drought condition at ripening stage. Furthermore, wheat quality became deteriorate in drought condition at ripening stage.

• Biomolecules & Therapeutics
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• v.27 no.4
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• pp.386-394
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• 2019

Trypanosoma cruzi infection results in debilitating cardiomyopathy, which is a major cause of mortality and morbidity in the endemic regions of Chagas disease (CD). The pathogenesis of Chagasic cardiomyopathy (CCM) has been intensely studied as a chronic inflammatory disease until recent observations reporting the role of cardio-metabolic dysfunctions. In particular, we demonstrated accumulation of lipid droplets and impaired cardiac lipid metabolism in the hearts of cardiomyopathic mice and patients, and their association with impaired mitochondrial functions and endoplasmic reticulum (ER) stress in CD mice. In the present study, we examined whether treating infected mice with an ER stress inhibitor can modify the pathogenesis of cardiomyopathy during chronic stages of infection. T. cruzi infected mice were treated with an ER stress inhibitor 2-Aminopurine (2AP) during the indeterminate stage and evaluated for cardiac pathophysiology during the subsequent chronic stage. Our study demonstrates that inhibition of ER stress improves cardiac pathology caused by T. cruzi infection by reducing ER stress and downstream signaling of phosphorylated eukaryotic initiation factor ($P-elF2{\alpha}$) in the hearts of chronically infected mice. Importantly, cardiac ultrasound imaging showed amelioration of ventricular enlargement, suggesting that inhibition of ER stress may be a valuable strategy to combat the progression of cardiomyopathy in Chagas patients.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.276-287
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• 1990

In this paper research result of transient thermal stress analysis of power plant turbine rotors for life prediction under severs operating conditions is presented. Galerkin's recurrence scheme is used for numerical solution of discretized FEM equation of transient heat conduction equation. Boundary conditions for the equation and operating conditions are intensively investigated for accurate life prediction of turbine rotors in operation. A computer program for on-site application is developed and tested. Distribution of thermal stress in turbine rotors during various operating condition is analyzed with the program and it is found that the peak thermal stress appears during cold stage conditions at the first stage of high pressure rotors.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1366-1377
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• 2020

The purpose of this study was to confirm the effect of the Havruta-based teaching and learning method on the academic self-efficacy, critical thinking tendency, learning satisfaction, and academic stress of nursing students. This study was conducted with 90 2nd graders of nursing department with one-group pretest-posttest design. The Havruta-based instructional design consists of five stages: the 1 stage is the pre-learning stage, the 2 stage is the introduction and development stage, the 3 stage is the organization of the class content, the 4 stage is the question and teaching stage, and the 5 stage is organized and integrated. Four weeks of Havruta-based teaching and learning method was applied. The data were analyzed by SPSS 25.0. The general characteristics of the subjects were frequency and percentage, and The dependent variable for measuring the effect of experimental treatment was analyzed by paired t-test. As a result of the study, the application of the Havruta-based teaching and learning method showed statistically significant results on academic self-efficacy(t=-3.711, p<.000), learning satisfaction(t=-2.580, p=.012), and academic stress(t=6.500, p<.000). The Havruta-based teaching and learning method has been confirmed to be an effective teaching method that increases the subject's academic self-efficacy, learning satisfaction, and lowers academic stress, so it can be applied to other major subjects in the future.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.119-119
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• 2017

Growth related to morphological and proteome response under waterlogging stress in sorghum has not yet been elucidated. Understanding how plants respond to waterlogging, the present study was conducted in seedlings leaf of the Nam-pung chal cultivar. Regarding 3-leaf stage of sorghum, stem length and plant height were slightly decreased in the treatments during ten days of waterlogging, and chlorophyll contents were also significantly different from 7 days of waterlogging treatment. The results observed from the present study were considered to be influenced by the waterlogging stress more in the $5^{th}$ leaf stage of the growth period of the sorghum, and as the waterlogging treatment progressed, the waterlogging stress gradually influenced the growth difference between the control and the treatment respectively. Using 2-DE method, a total of 74 differentially expressed protein spots were analyzed using LTQ-FT-ICR MS. Of these proteins, 45 proteins were up-regulated in the treatment group, and 32 proteins were down-regulated. Analysis of LTQ-FI-ICR MS showed that about 50% of the proteins involved in carbohydrate metabolic process, metabolic process, and cellular metabolic compound salvage were affected by stress. Malate dehydrogenase protein and Glyceraldehyde-3-phosphate dehydrogenase protein related to carbohydrate metabolic process increased the level of protein expression in both 3 and 5-leaf stage under waterlogging stress. The increased abundance of these proteins may play an active role in response to waterlogging stress. These results provide new insights into the morphological alteration and modulation of differentially expressed proteins in sorghum cultivar.

• Korean Journal of Adult Nursing
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• v.13 no.2
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• pp.317-326
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• 2001

The purpose of this study was to identify correlation of stress, coping patterns and physical symptoms in cancer patient's caregiver. The stress was measured by VAS(Visual Analogue Scale). The coping methods were measured using the modified Ways of Coping Questionnaire by Yang (1998) and the actual physical symptoms were investigated. The phases of patient illness consisted of 1st (initial) stage, and 2nd (recurred) stage and 3rd (terminal) stage based on literature (Lewandowski & Jones, 1988). The data were collected by a survey conducted from March to July, 2000 and which included 196 cancer patients' caregivers from two hospitals in Seoul. The data were analyzed using paired t-test, unpaired t-test, ANOVA, Scheffe test and Pearson correlation coefficient. The results were as follows: 1. The average of caregivers' stress scores was 62.5. Problem-focused coping methods were significantly used more than emotion-focused coping methods by the cancer patients' caregiver. The mean number of caregivers' physical symptom was 1.03. 2. There were significantly high level of stress in women, those who were more than 60 years old, those who had a low education level, those who had no job, those who are patients' wives' and those who are terminal patients' caregiver. There were significantly low levels of coping in women, those who were more than 60 years old, those who had low education levels, those who had no job and those who are patients' wives. There were significantly higher number of physical symptoms in women, and those who have no job. 3. Caregivers' stress was significantly correlated to problem-focused coping methods (r=-.21, p=.006), and physical symptom (r=-.28, p=.0001). In conclusion, attempts to develop nursing interventions for cancer patients' caregiver in women, those who are more than 60 years old, with a low education level, have no job, and are cancer patients' wives could have an improvement on positive coping methods and provide relaxation from stress in the patients' experience.

• Women's Health Nursing
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• v.6 no.4
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• pp.493-505
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• 2000

The purpose of this study was to contribute to maternal nursing in the early postpartum stage and neonate nursing. Data were collected through self-report questionaires which were constructed to include perception of the newborn scale, parental role stress scale and anxiety scale. The subjects consisted of 81 mothers of preterm babies at seven hospitals in Seoul and Kyoungki-Do, from July 15 to September 30, 2000. Data were analysed by SPSS/PC using frequency, percentage, mean, standard deviation, ANOVA, t-test and Pearson correlation coefficient. The results were summarized as follows ; 1. The mean of perception of the newborn in the early postpartum stage was 1.35. The mean of parental role stress was 10.78. The mean of anxiety of mother was 39.74. 2. There were significant positive correlation between parental role stress and anxiety of mothers. 3. There were not significant influencing general characteristics to perception of the newborn and parental role stress. General characteristics related to the level of anxiety were economic status, expectation of pregnancy, birthing order, newborn weight. The above findings indicated that the level of parental role stress and anxiety of preterm birth mothers were correlated. Therefore nursing intervention for reducing parental role stress and anxiety should be provided for preterm birth mothers.