• Journal of Applied Biological Chemistry
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• v.44 no.4
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• pp.159-162
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• 2001

Plant stress incurred by flooding was studied in terms of oxidative stress, using greened rice seedlings subjected to a complete submergence followed by re-exposure to air under illumination ($30W/m^2$). It appeared that shoot tissues of the seedlings suffered oxygen deficiency during the flooding treatment, pertinent to the general concept. Interestingly enough, however, membrane peroxidation in shoots was enhanced by the submergence, as assessed by the content of 2-thiobarbituric acid-reactive substances (TBARS), and the re-aeration resulted in a rapid reduction of TBARS content. Such pattern of response was also seen in the change in the steady state level of $H_2O_2$. In contrast, superoxide dismutase and glutathione reductase that are involved in the detoxifying processes of superoxide in plant cells were significantly activated only during the re-aeration. These results allowed us to suggest the followings as a working hypothesis. Photorespiration-linked production of $H_2O_2$ may largely contribute to the increase in $H_2O_2$ level as well as TBARS production in shoots during the submergence. An abrupt re-supply of $CO_2$ by the re-aeration brings the photosynthetic apparatus back to full operation, suppressing photorespiration and probably causing a momentary, excess formation of superoxide and its dismutation product through side reaction, which gives rise to activating substrate-inducible antioxidative enzymes.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.205-212
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• 2003

This paper may provide a basic design data for the safer car seat mechanism and the quality of the material used by finding out the passenger's dynamic behavior when protected by seat belt during collision. A computer simulation with finite element method is used to accomplish this objective. At first, a detailed geometric model of the seat is constructed using CAD program. The formation of a finite element from a geometric data of the seat is carried out using Hyper-Mesh that is the commercial software for mesh generation and post processing. In addition to seat modeling, the finite element model of seat belt and dummy is formed using the same software. Rear impact analysis is accomplished using Pam-Crash with crash pulse. The part of the recliner and right frame is under big stress in rear crash analysis because the acceleration force is exerted on the back of the seat by dummy. The stress condition of the part of the bracket is checked as well because it is considered as an important variable on the seat design. Front impact model which including dummy and seal belt is analyzed. A Part of anchor buckle of seat frame has high stress distribution because of retraction force due to forward motion of dummy at the moment of collision. On the basis of the analysis result, remodeling and reanalysis works had been repeatedly done until a satisfactory result is obtained.

• Geomechanics and Engineering
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• v.8 no.1
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• pp.1-15
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• 2015

This paper presents a series of conventional undrained triaxial compression tests conducted to determine the effect of both tire crumbs and cement addition on Narli sand specimens. The tire crumb contents and cement contents were 3%, 7%, 15%; and 1%, 3%, 5% by dry weight of the sand specimens respectively. Specimens were prepared at about 35% relative density, cured during overnight (about 17 hours) for artificially bonding under a 100 kPa effective stress (confining pressure of 500 kPa with a back pressure of 400 kPa), and then sheared. Deviatoric stress-axial strain, pore water pressure-axial strain behavior, and Young's modulus of the specimens at various mixture ratios of tire crumb/cement/sand were measured. Test results indicated that the addition of tire crumb to sand decreases Young's modulus, deviatoric stress and brittleness, and increase pore water pressure generation. The addition of cement to sand with tire crumbs increases deviatoric stress, Young's modulus, and changes its ductile behavior to a more brittle one. The results suggest that specimen formation in the way used here could reduce the tire disposal problem in not only economically, and environmentally, but also more effectively beneficial way for some geotechnical applications.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.11-16
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• 2008

In this paper, firstly we made of the rapid thermal processor equipment with the specifically useful structure to measure wafer stress. Secondly we made of the laser interferometry to inspect the wafer surface curvature based on the large deformation theory. And then the wafer surface fringe image was obtained by experiment, and the full field stress distribution of wafer surface comes into view by signal processing with thining and pitch mapping. After wafer was ground by 1mm and polished from the back side to get easily deformation, and it was heated by three to four times thermal treatments at about 1000 degree temperature. Finally the severe deformation between wafer before and after the heat treatment was shown.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1303-1309
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• 2003

This paper presents the static and dynamic measurements for the strength and motion characteristics as well as the improved procedures to assess strength of wheel loaders. Two scenarios for static measurement were decided by which cylinder was actuating. The dynamic measurement was performed for two types of motion, that is, simple reciprocation of the working devices and actual working motion including traveling, digging and dumping. The measured items were stresses, cylinder pressures and strokes. Stress induced by bucket working showed higher level than that by boom working. The measured cylinder speeds were relatively superior to the design speeds. Working stress histories were thought to be closer to static rather than dynamic. A fully assembled FE model was prepared for structural analysis. In this paper, a more simple method was suggested to avoid nonlinearity caused by heave of rear frame under digging forces. Also how brake affected on structural behavior and digging force was examined closely in relation with tire pressure. It was confirmed that the overall stress level of wheel loader during turning traveling with loaded bucket was far lower than the yield stress of material.

• Journal of muscle and joint health
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• v.24 no.3
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• pp.159-170
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• 2017

Purpose: The purposes of this study were to identify musculoskeletal symptoms and to investigate factors associated with musculoskeletal symptoms in small and medium sized hospital nurses. Methods: The data were collected from 206 nurses working in Jeonnam. We used self administration questionnaires of KOSHA GUIDE H-9-2012 for musculoskeletal symptoms, PWI-SF for psychosocial stress, KOSS for job stress, and HPLP-II for health behaviors. The collected data were analyzed using the $x^2$, t-test, and logistic regression analysis in SPSS Ver. 23.0. Results: Sixty-six percent of the subjects had musculoskeletal symptoms. The shoulder had the highest symptom at 38.3%, followed by lower back at 32.5%, and neck at 29.1%. The mean and standard deviation score of psychosocial stress were $24.06{\pm}6.01$, those of job stress were $2.38{\pm}0.23$, and those of health behaviors were $2.14{\pm}0.39$. The items that were significantly different according to musculoskeletal symptoms were career ($x^2=6.67$, p<.036), one week overtime ($x^2=7.27$, p<.026), subjective health status ($x^2=4.29$, p<.038), and psychosocial stress ($x^2=7.99$, p<.010). In logistic regression analysis, career, and psychosocial stress were found to affect musculoskeltal symptoms. Conclusion: It is necessary to conduct preventive intervention to reduce musculoskeletal symptoms according to career and psychosocial stress for small and medium sized hospital nurses.

• The Korean Journal of Pain
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• v.30 no.2
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• pp.126-133
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• 2017

Background: There are many mechanisms in which stress can lead to weight gain thus high a BMI. The endocrine and inflammatory pathway can directly increase abdominal adiposity. Another way in which stress leads to weight gain is through changes in health behaviors. The study aimed to investigate the prevalence of musculoskeletal disorders (MSDs) among healthy students of Ahlia University, and to determine the relationship between the development of MSDs and academic stressors and body mass index. Methods: Self-administered questionnaires were distributed to 94 students aged 18-26 years who were enrolled at various Ahlia University colleges and met other inclusion criteria. The students responded to the standardized Nordic musculoskeletal questionnaire and the modified College Student Stress Inventory regarding musculoskeletal symptoms and academic stressors. Height and weight measurements were also obtained to determine body mass index. Results: A total of 77.66% reported MSDs in one or more body part, with the prevalence being higher among women than among men. The 7-day prevalence of MSDs severe enough to interfere with activities of daily living was 60.64%, and 44.68% by female and male students, respectively. There was a significant relationship between academic stress and MSDs in the neck, shoulders, lower back, and hips, while the relationship between MSDs, and body mass index, academic stress, and grade point average was not significant. Conclusions: The prevalence of MSDs among Ahlia University students was found to be high. Apart from the positive correlation between academic stress and MSDs in certain body parts, other correlations were not significant.

• Geomechanics and Engineering
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• v.37 no.1
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• pp.73-84
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• 2024

Owing to the high strength and abrasive characteristics of cobble-boulders, cutters are easily worn and damaged during shield tunneling, making construction inefficient. In the present work, the stress on the ripper and scraper on the cutterhead was analyzed by the PFC3D-FLAC3D coupling model of shield tunneling to get insight into the performance of the cutterhead for cutting underground cobble and boulders. The numerical calculation results revealed that the increase in trajectory radius leads to a rising stress on the cutters, and the stress on the front cutting surface is greater than that on the back of the cutters. Moreover, the correlation between cutter wear and stress is revealed based on field measurement data. The distribution of the cutter stress is consistent with the cutter wear and breakage characteristics in actual construction, in which more extensive cutter stress is exhibited, extreme cutter wear appears, and more cutter breakage occurs. Finally, the relationship between the cutterhead opening area's layout and cutter wear distribution was investigated, indicating that the cutter wear extent is the most severe in the region where the radial opening ratio dropped sharply.

• Nutrition Research and Practice
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• v.7 no.6
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• pp.430-438
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• 2013

Increased oxidative stress in obese diabetes may have causal effects on diabetic complications, including dyslipidemia. Lipopolysccharides (LPS) along with an atherogenic diet have been found to increase oxidative stress and insulin resistance. Cranberry has been recognized as having beneficial effects on diseases related to oxidative stress. Therefore, we employed obese diabetic animals treated with an atherogenic diet and LPS, with the aim of examining the effects of cranberry powder (CP) on diabetic related metabolic conditions, including lipid profiles, serum insulin and glucose, and biomarkers of oxidative stress. Forty C57BL/KsJ-db/db mice were divided into the following five groups: normal diet + saline, atherogenic diet + saline, atherogenic diet + LPS, atherogenic diet + 5% CP + LPS, and atherogenic diet + 10% CP + LPS. Consumption of an atherogenic diet resulted in elevation of serum total cholesterol and atherogenic index (AI) and reduction of high density lipoprotein (HDL)-cholesterol. However, with 10% CP, the increase in mean HDL-cholesterol level was close to that of the group with a normal diet, whereas AI was maintained at a higher level than that of the group with a normal diet. LPS induced elevated serum insulin level was lowered by greater than 60% with CP (P < 0.05), and mean serum glucose level was reduced by approximately 19% with 5% CP (P > 0.05). Mean activity of liver cytosolic glutathione peroxidase was significantly increased by LPS injection, however it was reduced back to the value without LPS when the diet was fortified with 10% CP (P < 0.05). In groups with CP, a reduction in mean levels of serum protein carbonyl tended to occur in a dose dependent manner. Particularly with 10% CP, a reduction of approximately 89% was observed (P > 0.05). Overall results suggest that fortification of the atherogenic diet with CP may have potential health benefits for obese diabetes with high oxidative stress, by modulation of physical conditions, including some biomarkers of oxidative stress.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.757-762
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• 2002

Many reports have been shown that the buoyancy, electromagnetic force, surface tension, and gas shear stress are the driving forces of weld pool circulation in arc welding. Among them, the surface tension of molten metal plays an important role in the flow in weld pool, which are clarified by the specially designed experiments with small particles as well as the numerical simulations. The surface tension is also related to the penetration in arc welding. Therefore, a quantitative evaluation of surface tension is demanded for the development of materials and arc process control. However, there are few available data published on the surface tension of molten metals, since it depends on the temperature and the composition of materials. In this study, a new method was proposed for the evaluation of surface tension and its temperature dependence, in which it is evaluated by the equilibrium condition of acting forces under a given surface geometry, especially back surface. When this method was applied to the water pool and to the back surface of molten pool in the stationary gas tungsten arc welding of thin plate, following results were obtained. In the evaluation of surface tension of water, it was shown that the back surface geometry was very sensitive to the evaluation of surface tension and the evaluated value coincided with the surface tension of water. In the measurement of molten pool in the stationary gas tungsten arc welding, it was also shown that the comparison between the surface tension and temperature distribution across the back surface gave the temperature dependent surface tension. Applying this method to the mild steel and stainless steel plates, the surface tension with negative gradient for temperature is obtained. The evaluated values are well matched with ones in the published papers.