• Transactions of Materials Processing
• /
• v.15 no.4 s.85
• /
• pp.295-303
• /
• 2006

Optimization is carried out to determine process parameters which reduce the amount of springback and improve shape accuracy of a deep drawn product in sheet metal forming process. The study uses the amount of stress deviation along the thickness direction in the deep drawn product as an indicator of springback instead of springback simulation. The scheme incorporates with an explicit elasto-plastic finite element method for calculation of the final shape and the stress deviation The optimization method adopts the response surface method in order to seek for the optimum condition of process parameters such as the blank holding force and the draw-bead force. The present scheme is applied to design of the variable blank holding force in an U-draw bending process and the application is further extend ε d to the design of draw-bead force in a front side member formed with advanced high strength steel (AHSS) sheets of DP60. Results show that design of process parameter is well performed to decrease the stress deviation through the thickness and to reduce the amount of springback. The present analysis provides a guideline in a design stage for controlling the springback based on the finite element simulation of the complicated parts.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2006.06a
• /
• pp.61-67
• /
• 2006

Optimization is carried out to determine process parameters which reduce the amount of springback and improve shape accuracy of a deep drawn product in sheet metal forming process. The study uses the amount of stress deviation along the thickness direction in the deep drawn product as an indicator of springback instead of springback simulation. The scheme incorporates with an explicit elasto-plastic finite element method for calculation of the final shape and the stress deviation. The optimization method adopts the response surface method in order to seek for the optimum condition of the draw-bead force. The present scheme is applied to the design of draw-bead force in a front side member formed with advanced high strength steel (AHSS) sheets of DP60. Results show that design of process parameter is well performed to decrease the stress deviation through the thickness and to reduce the amount of springback. The present analysis provides a guideline in a design stage for controlling the springback based on the finite element simulation of the complicated parts.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.3 no.2
• /
• pp.247-258
• /
• 1996

This study explored the variables to influence the stress of the family caregivers providing care for the hospitalized elderly The subjects for this study were 104 family caregivers selected from the caregivers in the in patient departments of two major medical centers in Jeonju city. Data were collected from December 18th to 27th, 1995 using a Liker Scale Questionaire and interview. Data analyses included percentage, mean, standard deviation, t and F-test. Results were following : 1. The mean of this sample is 21.48, and the standard deviation is ${\pm}5.64$ in the perceived stress. The major variables to influence on the stress of caregivere for the hospitalized elderly were the stay (16-24hrs/day) in hospital(F=7.99, p=0.006), no other helpers(t=-2.56, P=.012), percieving severely on illness(F=3.90, P=.0232) perceiving moderately on physical health status(F=6.20, P=.0029). 2. Regarding the perceived social support of the family caregivers, the higher support the group perceived the lower stress(F=3.54, P=.0326).

• Journal of Welding and Joining
• /
• v.32 no.1
• /
• pp.61-65
• /
• 2014

The purpose of this study is to evaluate the applicability of the element stress to establish S-N design curve for the welded lap joint with thin plates below 2mm thickness. In order to do it, the extensive fatigue tests of the welded lap joints with INVAR alloy were performed. With the results, the deign S-N curves for the lap-weld were established by using the reference stresses such as the nominal stress range at the weld throat area, hot spot stress range and element stress range, and compared with regard to the standard deviation. The standard deviation of S-N curves with element stress range was less than that of S-N curves with other reference stresses. In addition, FEA results show the amount of the element stress is less sensitive to mesh size. Based on the results, it can be concluded that the element stress is to be used as the reference stress for the design S-N curves of the welded lap joint.

• Structural Engineering and Mechanics
• /
• v.33 no.1
• /
• pp.67-77
• /
• 2009

The soil response calculation is described, by which, threw the fictive path of stress, the stress-deformation diagrams are determined, considering the nonlinear soil behavior. The calculation are lead incrementally, by which is shown that in the presented soil model (modified Cam Clay), considering the influence of overconsolidated soil pressure OCR, the number of calculation steps may, but not necessarily, have a sufficient influence on the value of failure load and definite soil deformation. The simplicity and the practicalness of the procedure, the enables modeling the complex relations in soil.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.09a
• /
• pp.777-777
• /
• 2005

• Journal of the Ergonomics Society of Korea
• /
• v.19 no.2
• /
• pp.15-31
• /
• 2000

The aim was to evaluate the prevailing ergonomic and psychosocial conditions regarding low back injury in an automobile assembly system. This study consisted of two parts. In the first part of the study, analytic biomechanical model and NIOSH guidelines were applied to evaluate risk levels of low back injury for automobile assembly jobs. Total of 246 workers were analysed. There were 20 jobs having greater back compressive forces than 300kg at L5/S1. Also, there were 44 jobs over Action Limit with respect to 1981 NIOSH guidelines. This might in part be explained by the ergonomic conditions of the company analysed generally being good, with a relatively low duration of 'combined' extreme work posture. The relationship between psychosocial factors and low back injury was examined in the second part of the study. It has recently been recognized that overall reaction to working conditions was influenced by a range of factors, some of which were physical and some psychosocial. The psychosocial environment surrounding the work place may contribute to the perception of risk and eventual ill-health. A battery of questionnaires concerning the psychosocial stress based on PWI(Psychosocial Well-being Index) and musculoskeletal pain symptoms at low back was completed by 246 workers at the same plant. Results showed that 207 out 246 workers experienced the symptoms and 27 workers were diagnosed as patients. Two groups(low stressed, high stressed) based on PWI score had no significant relationships with both symptoms and results of diagnosis. However, sensitivities for symptoms and diagnosis by PWI were 91.3% and 92.6% respectively. Finally, relationships between physical work load and psychosocial stress were analysed. Specifically, some postural factors {vertical deviation angle of forearm, horizontal deviation angle of upperarm, vertical deviation angle of thigh, etc) were highly correlated with psychosocial stress. The results illustrated that PWI scores were associated with some physical workloads. However, psychosocial stress levels couldn't be well related with the pain symptom as well as the actual incidence of low back injury since pain or discomfort regarding low back injury were more complex than that of other musculoskeletal disorders.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.5
• /
• pp.774-781
• /
• 2013

A structural analysis was carried out for a 60 N.m class flexible disk coupling. Flexible disk couplings are used to transmit power between two shafts. When a flexible coupling is used, some amount of misalignments such as angle of deviation and end play can be allowed in assembling the shafts. However, the maximum allowable misalignment should be decided to guarantee the fatigue life. In this study, the effect of the angle of deviation and end play on the maximum stress was investigated. From the analysis results, it was shown that the angle of deviation has a greater effect on the maximum stress than the end play. Furthermore, the dimensions of the disk plate were optimized to realize a better design. From the optimization, the maximum stress could be reduced by up to 5.2%.

• Research in Community and Public Health Nursing
• /
• v.13 no.2
• /
• pp.354-362
• /
• 2002

Objectives: This study was conducted to examine the relationships among perceived life stress, self-esteem, and depression in middle-aged women. Methods: Data were collected from March 30 to May 25, 2000. The study subjects were 123 middle-aged women living in Pusan. The instruments used for this study were the Perceived Life Stress scale developed by Lee (1984), based on the original scale designed by Yu, et al. (1994), Self-esteem scale developed by Rho, et al. (1997), and the Depression scale developed by Ahn (1988). For data analysis, the SPSS PC+ was utilized, by which frequency and percentage, mean and standard deviation, t-test, ANOVA, Sheffe's test and Pearson's correlation coefficients were examined. The reliability of the instruments were tested by Cronbach's $\alpha$, showing the internal consistency of 0.7328 for the self-esteem scale. and 0.8987 for the depression scale. Results: 1) The results showed a relatively low perceived life stress score in the middle-aged women with a mean and standard deviation of 363.18 and 72.92 (range: .00 - 1877.38). 2) The results showed a relatively high self-esteem score in the middle-aged women with a mean and standard deviation of 29.77 and 5.06 (range: 10 - 40). 3) The results showed a relatively high depression score in the middle-aged women with a mean and standard deviation of 39.46 and 9.38 (range: 0 - 61). 4) There were no statistically significant differences in perceived life stress by demographic related factors. 5) There were statistically significant differences in self-esteem by health status (F=8.930, p= .000) and economic status (t=4.792, p= .010). 6) There were statistically significant differences in depression by age (F=3.770, p= .0261). education (F=4.850, p= .003) and regularity of menstrual cycle (F=13.180, p= .000). 7) There was no statistically significant correlation between perceived life stress, and self-esteem in the middle-aged women (r=-.077, p= .399). 8) There was no significant correlation between perceived life stress. and depression in the middle-aged women (r= .010, p= .916). 9) There was a significant negative correlation between self-esteem, and depression in the middle-aged women (r=- .359, p= .000). Conclusion: Higher self-esteem was related to a lower depression status. Therefore, it is necessary to elevate the level of self-esteem in order to reduce the level of depression in middle-aged Korean women.

• Journal of Korean Public Health Nursing
• /
• v.9 no.1
• /
• pp.44-58
• /
• 1995

This study was to investigated the relationship between health locus of control and health promoting behavior of College students. For this study, questionnaires were given to 300 students in the H University of Seoul and collected during the period from Nomber 17 to November 24, 1994. Health locus of control and health promoting behavior were measured by using the MHLC scale and a modified HPLP scale. Healthiness of life style is parameterized by self actualization, health responsibility, exercise, nutrition, stress management, and internal support. The data were analyzed using the statistics package SAS, yielding frequency, percentage, mean, standard deviation, t-test, ANOVA, Pearson's Correlation. The result of this analysis are as follows: 1. Among the components of health locus of control, internal health locus of control showed the highestscore (mean: 3. 12, standard deviation: 0.46). Powerful others health locus of control followed next with the mean of 2. 30 and the standard deviation of 0.44. Chance health locus of control showed the mean of 2.29, and the standard deviation of 0.43 2. The HPLP mean score and the standard deviation of practice of health promoting behavior were 2.51 and 0.31 respectively. 3. HPLP correlated positively with internal health locus of control (r= 0.20, p<.01) and powerful others locus of control (r= 0.21. p<.001). However, HPLP inversely correlated with chance locus of control (r=-0.13, p<.05) 4. The demographic variables representing sex (t= 2.26, p<.05), health status (F = 5.52, p<.01) showed connections to health promoting behavior. Therefore, nurses should consider health locus of control when they take care of College students to improve such health promoting behavior as self actualization, exercise, internal support, stress management, and health responsibility. Further research is required to discover factors influencing health promoting behavior of College students.