• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.2
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• pp.101-106
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• 2006

The optimum design of turbine blade at minimized fatigue life can be derived by the statistical fatigue analysis in this study, The optimum value of positions in the axes of X and Y at turbine blade can be found by design of experiments on the condition that the value of fillet radius is fixed to minimize the fatigue life. The degree of uncertainty about process at the factors in the axes of X and Y can be calculated by six sigma analysis. The optimum value of fillet radius is determined by utilizing the robust design at uncertain condition. It is concluded that maximum von Mises stress can decreased by 20% and the fatigue life can be double.

• Journal of Welding and Joining
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• v.28 no.4
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• pp.49-54
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• 2010

Stainless steel sheets are widely used as the structural material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the GMAW (gas metal arc welding). For fatigue design of GMA welded joints such as fillet and plug, ring type joint, it is important to obtain optimum design factor information on GMA welded joints. in this paper, analysis approach for fatigue test using design of experiment are evaluated optimum factor in GMA welded joint type and geometrical parameters of materials. Using these results, that factors applied to fundamental information for fatigue design.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.132.2-132.2
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• 2005

• Proceedings of the Korea Society of Design Studies Conference
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• 2001.10a
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• pp.43.2-43
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• 2001

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.242-249
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• 1999

Spot welding is very important and useful technology in fabrication of an automobile body structure. Because fatigue strength of the spot welding point is however considerably lower than parent metal due to stress concentration at the nugget edge, accurate stress analysis and fatigue stength evaluation of spot welded lap joint are very important to valuate the reliability and durability of automobile body structure and to establish a criterion of long life fatigue design. Many invetigators have studied so far onsystematic fatigue strength evaluation with various methods. It is however necessary to verify their reliability and abailability for practical application to fatigue design of spot welded structure, Thus,in this study, fatigue strength evaluation methods of spot welded lap joint. which are the maximum principal stress method. the fracture and availability with the Weibull probability distribution. From the results, it was found that reliability and availability withe the Weibull probaility distribution. From the results, it was found that reliability and availability of the suggest fatigue strength estimation methods methods were higher than $\Delta$P-$N_f$ relation. However, among them , reliability of the maximum pricipal stress method was the highest.

• Asian Oncology Nursing
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• v.5 no.2
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• pp.87-96
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• 2005

Purpose: The purpose of this study was to identify the relationship between fatigue and nutritional status in gastric cancer Design. A correlational and crossectional study design was used. Method: Fatigue was measured using the Revised Piper Fatigue Scale. The parameters for nutritional status consisted of BMI, Hb, Hct, total protein, albumin and lymphocyte count. Result: The mean score of fatigue was $94.31{\pm}22.08(mean\;average\;4.48{\pm}1.00)$. The subdimensional scores of fatigue revealed $34.15{\pm}8.76$ for behavior/severity, $22.00{\pm}7.93$ for cognitive/mood, $21.67{\pm}5.56$ for sensory, and $20.81{\pm}6.69$ for affective. And the level of BMI, Hb, & Hct were under the normal ranges. In the ancillary analysis, there was a significant difference on the fatigue scores by the groups of present diet(F=3.343, P=.026). Age, types of treatments, period after diagnosis and weight change were related to nutritional status. There was a significant negative correlation between fatigue and nutritional status(r=-.371, P=.004). Conclusion: Considering the relationship between fatigue and nutritional status, nurses can identify the risk group most vulnerable to fatigue and malnourishment in order to provide appropriate interventions for them.

• Journal of the Korean Society of Safety
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• v.34 no.5
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• pp.1-6
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• 2019

The mobile elevated work platforms(MEWPs) consist of work platform, extending structure, and car, and it is a facility to move persons to working positions. MEWPs are useful but composed complex pieces of equipments, and accidents are caused by equipment defects. Among them, accidents caused by fracture of the bolts fixing the extension structure and the turntable are increasing. In this study, fatigue failure and fatigue life of a turntable fixing bolt subjected to irregular fatigue load were analyzed by FEA. For this purpose, finite element modeling is proposed and structural analysis and fatigue analysis are performed simultaneously for fixing bolts. As a result of the structural analysis, it was confirmed that there is no risk of permanent deformation because the maximum stress acting on the fixing bolt is lower than the yield strength, and fatigue analysis was confirmed that the fatigue life is less than the design standard. The fatigue analysis results of this study can be effectively used for the design and the documentary assessment of the safety certification of the MEWPs by examining the fatigue life of the turntable fixing bolt.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.6
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• pp.67-73
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• 2022

Industrial inverters are used in a variety of fields for electric power supply. They may be exposed to vibration and heat once they are installed. This study focused on a framework of accelerated life testing of an industrial inverter considering fatigue damage as the primary source of deterioration. Instead of analyzing detailed failure mechanisms and the product's vulnerability to them, the potential of fatigue failure is considered using the fatigue damage spectrum calculated from the environmental vibration signals. The acceleration and temperature data were gathered using field measurement and spectral analysis was conducted to calculate the vibration signal's power spectral density (PSD). The fatigue damage spectrum is then calculated from the input PSD data and is used to design an accelerated fatigue life testing. The PSD for the shaker table test is derived that has the equivalent fatigue damage to the original input signal. The tests were performed considering the combined effect of random vibration and elevated temperature, and the product passed all the planned tests. It was successfully demonstrated that the inverter used in this study could survive environmental vibration up to its guarantee period. The fatigue damage spectrum can effectively be used to design accelerated fatigue life testing.

• Journal of Ocean Engineering and Technology
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• v.33 no.1
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• pp.33-41
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• 2019

Estimating fatigue damage is a very important issue in the design of ships. The springing and whipping response, which is the hydro-elastic response of the ship, can increase the fatigue damage of the ship. So, these phenomena should be considered in the design stage. However, the current studies on the the application of springing and whipping responses at the design stage are not sufficient. So, in this study, a prediction method was developed using fluid-structural interaction analysis to assess of the fatigue damage induced by springing and whipping. The stress transfer function (Stress RAO) was obtained by using the 3D FE model in the frequency domain, and the fatigue damage, including linear springing, was estimated by using the wide band damage model. We also used the 1D beam model to develop a method to estimate the fatigue damage, including nonlinear springing and whipping by the vertical bending moment in the short-term sea state. This method can be applied to structural members where fatigue strength is weak to vertical bending moments, such as longitudinal stiffeners. The methodology we developed was applied to 325K VLOC, and we analyzed the effect of the springing and whipping phenomena on the existing design.

• Women's Health Nursing
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• v.10 no.3
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• pp.235-243
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• 2004

Purpose: The purpose of this study was to measure the effects of aroma inhalation on fatigue and quality of sleep of postpartum mothers. Method: The study design was a non-equivalent control group pre-post design. 51 Postpartum mothers were assigned either to a control group or to an experimental group that was exposed to aromas through inhalation for 6 days. Subjects in the experimental group were instructed to wear a necklace filled with Lavender and Eucalyptus oil from 2:00 PM to 8:00 PM every day. Fatigue was measured using the Rhoten Fatigue Scale. Sleep duration, night arousal frequency and sleep satisfaction were used to assess the quality of sleep. Result: There was a significant difference in the score of fatigue following the treatment between the experimental and control groups (t=-2.79 p=.00). However, there was no significant difference in sleep duration, frequency of night arousal and sleep satisfaction following aroma inhalation between two groups. Conclusion: This intervention appears to be effective in reducing the fatigue in postpartum mothers.