• Journal of Ocean Engineering and Technology
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• v.7 no.2
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• pp.103-113
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• 1993

X-ray diffraction analysis technique was used for the fatigue damage analysis and fatigue life prediction in Al 7075-T651 alloy. The tensile test, fatigue strength and fatigue crack propagation test with change of stress ratio were carried out. As a result, half-value breadth was increased with the plastic deformation in the specimen increasint at all test conditions. In particular, half-value breadth at the surface of the specimens fractured by fatigue was increased as stress intensity factor range and effective stress intensity factor range were increased. In addition, the good relationship between half-value breadty and diffraction pattern was shown.

• Journal of KSNVE
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• v.6 no.4
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• pp.447-456
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• 1996

Dynamic characteristics of the bell-type structure including acoustic effects and transient dynamic problems were analyzed numerically. Natural frequencies, mode shapes and transient dynamic analysis used the finite element method with 3-D general shell element. Mode shapes and stress distributions of transient dynamic analysis were expressed by computer graphics. The method using this study was evaluated by comparision of theoretical results at reference papers(14), (15) and the experimental test using Fast Fourier Transform analyzer. Vibrational modes governing acoustic characteristics of the typical bell-type structure depended on the first flexural mode(4-0 mode) and the second flexural mode(6-0 mode). Asymmetric effects by Dangiwas, acoustic holes gave rise to beat frequencies, and the Dangjwa was found to be most effective. When impact load acted on the bell, stress concentration occured at the rim part of bell. It was found that the bell type structure should be designed thickly at the rim part in order to prevent impact load from stress concentration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.66-72
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• 2006

Marine diesel engine production and refinements sought a continuous increase on mean effective pressure and thermal efficiency. These results in increased maximum combustion pressure within the cylinder and vibratory torque in crankshaft. As such, crankshaft should be designed and compacted within its fatigue strength. In this paper, the 8H25/33P($3,155ps{\times}900rpm$) engine for ship propulsion was selected as a case study, and tile strength analysis of its crankshaft is carried out by. simplified method recommended by IACS M53 and a detailed method with the crankshaft assumed as a continuous beam and bearing supported in its flexibility. The results of these two methods are compared with each other.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.285-292
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• 2003

The soft structure can make large space more effectively, and its construction is easy and simple as well. However, it is not easy to realize this in the actual space. Therefore, two works are needed to be done for effective and accurate construction of soft structures. First, making a working scenario to complete the final objective form; second revising construction errors occurred in the middle of the actual works. These works are called constructional analysis. At this time, geometric nonlinearity should be considered to reflect the sensitivity by the initial stress of flexible structures, constructional analysis comes down to a nonlinear problem after all. This study approaches nonlinear constructional analysis with the numerical method for adjusting stress of cable-dome structures which are a soft structure system, and then verifies it.

• Safety and Health at Work
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• v.6 no.1
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• pp.35-38
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• 2015

Background: Organizational changes that involve healthcare hospital departments and care services of health districts, and ongoing technological innovations and developments in society increasingly expose healthcare workers (HCWs) to work-related stress (WRS). Minimizing occupational exposure to stress requires effective risk stress assessment and management programs. Methods: The authors conducted an integrated analysis of stress sentinel indicators, an integrated analysis of objective stress factors of occupational context and content areas, and an integrated analysis between nurses and physicians of hospital departments and care services of health districts in accordance with a multidimensional validated tool developed in Italy by the National Network for the Prevention of Work-Related Psychosocial Disorders. The purpose of this retrospective observational study was to detect and analyze in different work settings the level of WRS resulting from organizational changes implemented by hospital healthcare departments and care services of health districts in a sample of their employees. Results: The findings of the study showed that hospital HCWs seemed to incur a medium level risk of WRS that was principally the result of work context factors. The implementation of improvement interventions focused on team development, safety training programs, and adopting an ethics code for HCWs, and it effectively and significantly reduced the level of WRS risk in the workplace. Conclusion: In this study HCW resulted to be exposed to occupational stress factors susceptible to reduction. Stress management programs aimed to improve work context factors associated with occupational stress are required to minimize the impact of WRS on workers.

• Journal of Korean Academy of Nursing
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• v.33 no.3
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• pp.433-439
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• 2003

Purpose: The purpose of this study was to examine the relationship among subjective symptoms, depression, and stress coping behavior of university students. Method: The survey was carried out on a convenience sample of 298 university students. The questionnaire consisted of each scale for symptoms, depression, and stress coping behaviors. Data analysis procedure included the factor analysis for stress coping behaviors, and the correlation analysis describing a relationship among symptoms, depression, and stress coping behaviors. Result: There were significant correlations between depression and the three types of symptoms: general, psychological, and somatic symptom. Subjects using the negative-emotional-response coping and the self-control coping showed a more severe depression, and those using the problem-solvingㆍreappraisal coping and the positive-emotional-response coping showed a milder depression. Subjects using the negative-emotional-response coping complained of all 3 types of symptoms severely, and those using the positive-emotional-response coping complained of general symptoms mildly. Of five stress coping methods, the negative-emotional-response and the positive-emotional-response coping methods were related to both symptoms and depression significantly. Conclusion: This study suggests that the emotional-oriented coping method has more important role for university student’s depression and their subjective symptoms than the problem-oriented coping or social supports seeking coping. Further study needs to be conducted to help students effective coping mechanism for good mental health. Also it is necessary for university students to recognize that their symptoms are associated with depression.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.851_852
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• 2009

Shrink fitting which is assembling process to fix stator core on the motor frame is widely used at the mass production line of motors because of cost and productivity. This process produces compressive stress on a stator core, which causes negative effect for example, core and copper losses on motor performance. Magnetic properties of electrical steel are effected by both compressive and tensile and thermal stresses. Electromagnetic field analysis is considered one of the effective process since one can predict motor performance including core loss precisely. This method can consider non linear magnetic property with magnetic saturation which is typical electrical steel behavior. However this method is strongly depended on non linear magnetic data, one may have different calculation result whether considering mechanical stress or not. This study describes magnetic field analysis of a motor considering mechanical stress from shrink fitting. Analysis results are compared with each stress-free and stressed condition.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.599-608
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• 2002

Finite element analysis for the stress intensity factor (SIF) at the skin/stiffener structure with inclined central crack repaired by composite stiffened panels is developed. A numerical investigation was conducted to characterize the fracture behavior and crack growth behavior at the inclined crack. In order to investigate the crack growth direction, maximum tangential stress (MTS) criterion are used. Also, this paper is to study the performance of the effective bonded composite patch repair of a plate containing an inclined central through-crack. The main objective of this research is the validation of the inclined crack patching design. In this paper, the reduction of stress intensity factors at the crack-tip and prediction of crack growth direction are determined to evaluate the effects of various non-dimensional design parameter including; composite patch thickness and stiffener distance. We report the results of finite element analysis on the stiffener locations and crack slant angles and discuss them in this paper. The research on cracked structure subjected to mixed mode loading is accomplished and concludes that more work using a different approaches is necessary. The authors hope the present study will aid those who are responsible for the repair of damaged aircraft structures and also provide general repair guidelines.

• Journal of the Korean Home Economics Association
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• v.32 no.4
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• pp.57-71
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• 1994

The purpose of this research was to study the variables related to the stress and to provide the way of establishing better relationship between aged parents and adult offsprings and the way of effective care-giving. In order to achieve this purpose a survey was conducted by interview using questionaire. The collected data were analyzed by using frequency percentage mean standard deviation factor analysis Pearson's correlation analysis, ANOVA, and stepwise regression analysis. The results of this research were as follows: First The total points of daughter-in-laws' caregicing stress was 38.5 and daughter's caregiving stress was 27.3. Second There were meaningful differences according to living arrangement daughters-in-law age, old mothers' health status. And there were significant. interaction effects among variables of living arrangement and daughters-in-law' age, living arrangement and birth order birth order and old mothers' health status. living arrangement and daughters-in-law' age and old mothers' health status. Third There were meaningful differences according to living arrangement daughter's age. And there were significant interaction effects among variables of living arrangement and daughter's age, daughter's age and birth order, living arrangement and daughter's age and old mothers' health status, living arrangement and birth order and old mothers' health status. Fourth Among daughters-in-law' variables living arrangement age, old mothers' health status have influence on the care-giving stress. Among daughter's variables living arrangement, age, birth order have influence on the care-giving stress.

• Transactions of Materials Processing
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• v.25 no.3
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• pp.169-175
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• 2016

The hearth roll, which transfers the cold-rolled strip sheet in a Continuous Annealing Line (CAL), is always subjected to changes in the surface temperature and subsequently experiences thermal stress in service. These variations lead to the generation of thermal cracks on the hearth roll surface as well local plastic deformation. We performed finite element analysis to predict the thermal stress changes on the hearth roll surface and designed the collar shape of the hearth roll to minimize these thermal stresses. Results show that the hearth roll with a collar having an obtuse angle is much more effective than a hearth roll with collar having a right angle when the tangential stress, which is one of main causes leading to surface cracks, is compared for the various conditions. It was found that the tangential stress and the temperature on the surface of hearth roll can be reduced by 51.9% and 26℃ if the shape of roll on collar is re-designed.