• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.42-49
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• 2016

This study was analyed V-bending in order to analyze the spring-back phenomenon in the roll forming process. The material of forming sheet used in the roll forming process is high tension steel and the product name of sheet material is POSTEN 60. The most important variable is the number of roll passes (3-Pass, 4-Pass, 5-Pass, 6-Pass and 10-Pass) and other roll forming process variables were fixed. To determine the characteristics of the tension and compression, the forming sheet was analyzed by dividing the layer (Upper and Bottom) in the thickness direction from the center line. The results of FEM simulation analysis was derived to von-mises stress equivalent strain, and the spring-back value was calculated according to the final forming shape. The more number of the roll pass, von-mises stress and equivalent strain value of forming sheet were lowed. Also, spring-back values tended to decrease. The results of this study can be utilized for prediction and trend of spring-back value in the roll forming process applied to high tension steel sheet. So, development time and cost of the roll forming process is expected to be reduced.

• Korean Journal of Occupational Health Nursing
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• v.15 no.2
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• pp.115-125
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• 2006

Purpose: This study analyzed the amount of stress and the different effects according to the working times(hours) of a week in two groups: more than 40 hours a week and less than 40 hours a week. Method: The study was conducted from November 1st 2005 to December 15th 2005. The purpose of the study has already been explained in the experiment objectives. 20 copies of evaluation forms were sent by mail to 50 different health sections of participating work sites. A total of 1,000 copies were sent out and 870 were sent back. Within the forms, sent back 120 copies had insufficient data, so 750 copies of evaluation forms were analyzed. Result: Working stress for under 40 hours of working time showed a total of 46.10 points and 47.18 for over 40 hours of working time. For over 40 hours, job demand and occupational climate was high and under 40 hours showed a high rate of job control. For under 40 hours of working time, the factors that caused stress were female, irregular diet habit, age of 30's, nonmanufacturing, and single. For over 40 hours of working time, the factors that causes stress were age of over 40, when the number of employees is 500~999, high rate of fatigue, when the position of the employee is higher then section chief, and when the work amount is high. Conclusion: The stress rate showed significantly higher in over 40 hours of working time. Therefore, adequate working hour distribution and health promotion programs are needed. The factors that cause stress in both under and over 40 hours of working time differed. Therefore, a distinguished program to control work stress for additional working time is needed.

• Journal of muscle and joint health
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• v.16 no.1
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• pp.13-25
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• 2009

Purpose: The purpose of this study was to investigate the relationships between job stress and work-related musculo-skeletal symptoms among nurses working in general hospitals. Method: A descriptive correlational research design was utilized. The participants were 438 nurses currently working in 4 general hospitals. Data were collected from Jan 2007 to Feb 2007, with Korean Occupational Stress Scale(KOSS)-basic form, KOSHA code H-30 and a questionnaire for general characteristics. Descriptive statistics, t-test, ANOVA, multiple logistic regression analyses were utilized. Result: Most participants(90.4%) complained of work-related musculo-skeletal symptoms. However, symptomatic nurses satisfying NIOSH screening criteria(symptomatic nurses) were 66.9%(293 persons). The most complained body part was back(39.5%). shoulder(37.7%), leg and foot(36.5%), wrist and hand(21.7%), neck(18.7%), and arm(9.8%). The mean of total score of occupational stress was 51.11. In multiple logistic regression analyses, age, working posture and total score of occupational stress showed significant associations with back symptoms. Exercise and total score of occupational stress were significantly related with shoulder symptoms. Hours of daily house keeping and working posture were related with leg and foot symptoms. Marital status and working posture were related with wrist and hand symptoms. Working posture only showed significant relations with neck symptom. Marital status, hours of daily house keeping, shift work, working posture, and total score of occupational stress were related with the symptoms in the arm. In conclusion, job stress of nurses might be related with work-related musculo-skeletal symptoms.

• Tunnel and Underground Space
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• v.8 no.1
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• pp.46-52
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• 1998

The author conducted new back analysis method using monitoring data to a landslide which occurred around portal. In this case, because the tunnel being located under the sliding plane of the landslide, calculated value from the ordinary back analysis in which considered only stress release by the tunnel excavation didn't fit the measured value. Then, in the new method, a body force as the movement of the landslide mass was added to the ordinary back analysis and good results were obtained. Furthermore, the author carried out stability analysis of the landslide with the data of the back analysis and examined the loosened area and decreasing og the sliding plane strength due to the tunnel excavation.

• Transactions of Materials Processing
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• v.14 no.9 s.81
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• pp.751-755
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• 2005

This paper is concerned with spring back after sheet forming of bulk amorphous alloys in the super cooled liquid state. The temperature-dependence and strain-rate dependence of Newtonian/non-Newtonian viscosities as well as the stress overshoot/undershoot behavior of amorphous alloys are reflected in the thermo-mechanical Finite Element simulations. Hemispherical deep drawing operations are simulated for various forming conditions such as punch velocity, die comer radius, friction, blank holder force, clearance and initial funning temperature. Here, spring back by an instantaneous elastic unloading was followed by thermal deformation during cooling, and two modes of spring back are examined in detail. It could be concluded that the superior sheet formability of an amorphous alloy can be obtained by taking the proper forming conditions for loading/unloading.

• International Journal of Human Ecology
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• v.10 no.1
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• pp.87-98
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• 2009

This study examines the socio-cultural readjustment of the Korean students returning from overseas study at an early age. For this study 259 returnee students from elementary through high school completed a questionnaire which covered aspects such as school adjustment and re-acculturative stress in relationship to gender, grade, number of parents accompanying the students overseas, length of overseas stay, age of return, length of stay in Korea, and the acculturative stress experienced in a host culture. The findings indicate that re-acculturative stress level of returnee students is higher than the level of the acculturative stress, and that the two are positively related. Hierarchical multiple regression analyses reveal the grade and acculturative stress of returnee students as a significant predictor of school adjustment. The length of overseas stay and acculturative stress significantly predicted the re-acculturative stress level. The acculturative stress significantly affected both school adjustment and re-acculturative stress of returnee students back in Korea.

• Korean Journal of Occupational Health Nursing
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• v.14 no.1
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• pp.44-55
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• 2005

Purpose: The purpose of this study was to describe the current status of work-related back pain among nurses in the U.S. Method: Literature review and website searching were conducted. Key words as 'nurse and back pain (or back injury)' were used in searching the Medline, NIOSHTIC-2and reference list of selected studies. Total studies were selected of which subjects were nurses working in the U.S., and published since 1970. Results: Though there was variation in the measurement among studies, the prevalence rate of back pain among nurses in the U.S. could be estimated about 50%. Risk factors were confirmed as the frequency of patient lifting, ward, nursing shortage, overtime, work shift, stress on physical demand, but age and work experiences showed the inconsistent relation. It has been well known that educational approach is not enough to prevent back pain. Intervention studies to apply the ergonomic approach using mechanical devices reported the effects, but the devices were less diverse than European countries or Canada. The study for lifting team was rare. Federal government developed only the guideline for nursing home that had no legal obligation. As a professional nursing organization, ANA has been trying to educate and advocate for "No lift policy" since 2003. Meanwhile, two trade unions of nurses made efforts to establish the law strengthening the responsibility of health care facilities. Conclusion: The research and policy development will be needed to prepare to rapid increase of back pain among Korean nurses.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.896-905
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• 2012

Recently, the application of the plastic material to automotive components and structures has steadily increased to satisfy demands on the saving of overall weight and the improvement of energy efficiency. The objective of this paper is to investigate the development of a bumper back-beam using a thermoplastic olefin (TPO). The bumper back-beam was designed to be manufactured from the injection molding process. In order to obtain a proper design of the bumper back-beam, three-dimensional finite element analyses were performed for various design alternatives. Stress-strain curves for different strain rates were measured by high speed tensile tests of the TPO to consider strain rate effects in the FEA. The influence of the sectional shape and the rib formation on the contact force-intrusion curves, the deflection and the energy absorption rate of the bumper back-beam was examined. From the results of the examination, a proper design of the bumper back-beam was acquired. The bumper back-beam consisting of TPO was fabricated from the injection moulding process and the vibration welding. Pendulum crash tests were carried out using the fabricated bumper back-beam. The results of the tests showed that the designed bumper back-beam can satisfy requirements of the federal motor vehicle safety standard (FMVSS). Through the comparison of the previously designed bumper back-beam with the newly designed bumper back beam, it was noted that the weight of the designed bumper back-beam is lighter than that of the previously designed bumper back beam by nearly 16 %. In addition, it was considered that the newly designed bumper back beam can improve recycling of the bumper back-beam.

• The Journal of Korean Physical Therapy
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• v.2 no.1
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• pp.65-74
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• 1990

This study was carried out to measure the degree of work-related stress and to identify factors influencing the excessive stress among clinical physical therapists. One thousand and five physical therapists surveyed nationwide met the established criteria for inclusion in the study. The respondents were an average age of 27.1 years, $34.5\%$ were married, and $61.2\%$ were female. Most of the respondent $(48.1\%)$ worked in local clinics. The average stress score was 50.9. Analysis-of-variance test demonstrated significant difference in the degree of stress among treatment facilities. There was a significant relationship between treatment facilities (general hospital, local hospital, clinic), number of patients treated per day, job satisfaction, low back pain and work-related stress, respectively. Work-related stress was unrelated to matters of sex, marital status, education. Hospital administrators, physical therapydirectors, directors, and individual therapists should work within their organizations to reduce work stress and its detrimental effects. Further research is necessary to investigate preventive measures to decrease the work-related stress.

• Physical Therapy Korea
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• v.17 no.1
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• pp.53-61
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• 2010

This study investigated the relationships between Work-related musculoskeletal disorders (WMSDs), contributing factors, and the occupational stress of physical therapists. Self-reported questionnaires were given to 180 physical therapists in Gangwon Province. Variables examined included the prevalence of pain sites related to WMSDs; pain intensity; pain pattern; and job stress, which is thought to involve the physical environment; job demand; insufficient job control; interpersonal conflict; job insecurity; organizational system; reward system; and occupational culture. Among physical therapists, work-related musculoskeletal pain commonly affected the low back (30.1%), shoulder (29.3%), and wrist (12.2%). The sites of work-related musculoskeletal pain treated medically were the low back (22.8%), shoulder (19.8%), neck (12.7%), and wrist (12.1%). "Repeating the same work constantly" was suggested to be the major cause of the pain. The younger therapists were significantly more likely to feel high job stress due to the physical environment (p<.05), job demand (p<.05), and organizational system (p<.01). Women were more likely to feel greater job stress related to job demand, insufficient job control, the organization system, and job rewards. Men were more likely to feel greater job stress related to job insecurity. Weak positive relationships were observed between work-related musculoskeletal pain and job stress, which is thought to involve the physical environment; job demand; insufficient job control; interpersonal conflict; job insecurity; organizational system; reward system; and occupational culture. Physical therapists appear to be at higher risk of WMSDs because 80.1% of the physical therapists studied experienced work-related musculoskeletal pain. To reduce the risk, we need intervention strategies such as preventive education, ergonomically designed medical equipment, a psychosocial approach to work conditions, improved mechanical conditions related to therapeutic patterns, and an institutional infrastructure with sufficient personnel and scheduling.