• Korean Journal of Culture and Social Issue
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• v.12 no.3
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• pp.23-47
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• 2006

The purpose of this research is to study the relation between the change of driver's driving confidence level in the age categories and driving behavior. To survey the driving confidence level, we used the 'Driving Confidence Scale' questionnaire and surveyed the drive career, mileage, driving days, violation of traffic regulation (drunk driving, overspeed), traffic accident experience (assaulter, sufferer) together. The subjects of investigation were from 19-year-old to 80-year-old and 1,055 persons were participated in the research totally. To examinethe structure of driving confidence level, we executed the factor analysis. We compared the driving confidence level in the age categories (under 29-year-old, 30~39, 40~49, 50~64, over 65-year-old) and studied the relation between driving confidence level and driving behavior. Driving confidence level was composed of 4 factors such as 'insensibility to situation', 'unsafe driving', 'careless concentration' and 'self-efficacy of driving', and there was decreasing tendency for driving confidence level and overall driving behavior according to increasing age. Driving confidence level had the interrelation with age range, assaulting accident, suffered accident, driving period, drunk driving, overspeed, driving career and so on. We examined the difference of driving confidence level and driving behavior by dividing the participated drivers' groups into the traffic accident experienced group, drunk driving group and overspeed driving group, and there was a significant difference on driving confidence level and driving behavior between the group who had not experienced the violation of traffic regulation or traffic accident and another group who had experienced the violation of traffic regulation or traffic accident.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.131-139
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• 1993

Low cycle fatigue characteristics of cast aluminum alloy A356 with a yield strength and ultimate strength of 229 and 283 MPa respectively was evaluated using smooth axial specimen under strain controlled condition. Reversals to failure ranged from 16 to 107. The cast aluminum alloy exhibited cyclically strain-gardening behavior. The results of low cycle fatigue tests indicated that the conventional low cycle fatigue tests indicated that the conventional low cycle fatigue life model was not a satisfactory representation of the data. This occurred because the elastic strain-life curve was not-log-log linear and this phenomena caused a nonconservative and unsafe fatigue life prediction at both extremes of long and short lives. A linear log-log total strain-life model and a bilinear log-log elastic strain-life model were proposed in order to improve the representation of data compared to the conventional low cycle fatigue life model. Both proposed fatigue life models were statistically analyzed using F tests and successfully satisfied. However, the low cycle fatigue life model generated by the bilinear log-log elastic strain-life equation yielded a discontinuous curve with nonconservatism in the region of discontinuity. Among the models examined, the linear log-log total strain-life model provided the best representation of the low cycle fatigue data. Low cycle fatigue life prediction method based on the local strain approach could conveniently incorporated both proposed fatigue life models.

• Women's Health Nursing
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• v.14 no.3
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• pp.205-212
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• 2008

Purpose: The purpose of this study was to survey the health behaviors related to reproductive health, reproductive health history, and sexual behaviors of college students in local areas. Method: With a survey design, 792 college students from C and D areas were recruited to assess health behaviors such as smoking and alcohol drinking, as well as history of reproductive health and sexual behaviors. The data were collected by a self-administered questionnaire from November to December, 2007. Result: Mean age of the students was 20.8(SD=1.96) and gender distribution was 29.2% for male and 70.8% for female. Unhealthy behaviors were alcohol drinking, smoking, excessive weight loss, and irregular exercise; unsafe sex practices were experience of sexual intercourse with multiple sex partners and history of sexually transmitted disease (STD). Male students had more alcohol drinking (p=.04), smoking(p<.001), excessive weight loss(p=.01), experience of sexual intercourse with multiple sex partners(p<.001), history of STD(p=.025) compared to females. On the other hands, female students participated in regular exercise less than males(p<.001). Conclusion: College students seem to perform unhealthy behaviors related to reproductive health and less effective way of safe sex practices. Therefore, a planned education program for reproductive health promotion operated by college level is needed to assess and improve the level of reproductive health in college students.

• Structural Engineering and Mechanics
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• v.54 no.5
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• pp.855-875
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• 2015

Many novel materials exhibit a property of different elastic moduli in tension and compression. One such material is graphene, a wonder material, which has the highest strength yet measured. Investigations on buckling problems for structures with different moduli are scarce. To address this new problem, firstly, the nondimensional expression of the relation between offset of neutral axis and deflection curve is derived based on the phased integration method, and then using the energy method, load-deflection relation of the rod is determined; Secondly, based on the improved constitutive model for different moduli, large deformation finite element formulations are developed and combined with the arc-length method, finite element iterative program for rods with different moduli is established to obtain buckling critical loads; Thirdly, material mechanical properties tests of graphite, which is the raw material of graphene, are performed to measure the tensile and compressive elastic moduli, moreover, buckling tests are also conducted to investigate the buckling behavior of this kind of graphite rod. By comparing the calculation results of the energy method and finite element method with those of laboratory tests, the analytical model and finite element numerical model are demonstrated to be accurate and reliable. The results show that it may lead to unsafe results if the classic theory was still adopted to determine the buckling loads of those rods composed of a material having different moduli. The proposed models could provide a novel approach for further investigation of non-linear mechanical behavior for other structures with different moduli.

• Korean Journal of Construction Engineering and Management
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• v.20 no.6
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• pp.66-73
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• 2019

Thanks to various efforts to reduce disasters by the government and the Health and Safety Authority, disasters across industries and the construction industry show their reduction trend. However, the falling disasters in the construction industry have not decreased and increased on the contrary. Especially falling disaster caused by Hanging Scaffolding is the most critical disaster which shows low occurrence frequency but is directly connected to death of worker. The working environment for Hanging Scaffolding is poor in domestic construction site. In particular, the Hanging Scaffolding workers in small construction sites are not on the safety control and management by anyone for their works. They are driven to unsafe working condition with mostly uncertified facilities which are made by themselves. Therefore, this study is focused on searching falling disaster factors from the 242 disaster cases caused by Hanging Scaffolding Work in 15 years presented by KOSHA, and trying to provide suggestions for improvement. The improvement of the method of work requires facility improvement and work due to high accident rate caused by unsafe behavior. Analysis of the case of a disaster occurring over the past 15 years shows that no disaster occurred due to problems in the order of operations presented by KOSHA. However, it was found that many accidents resulted from death caused by safety belts not being installed or attached to ropes using safety belts without following the order of work. The most important aspect of improving the work method was the installation and wearing of lifeboats and safety belts.

• Computational Structural Engineering
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• v.10 no.3
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• pp.167-174
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• 1997

Engineers must be aware of possible sources of chaotic behavior. They may render conventional design predictions untrustworthy and potentially unsafe because of the sensitivity to initial conditions. Dynamic responses of a spherical shell subjected to impulsive loading which act on the center are analyzed using the finite element method. The chaotic responses are identified by the standard methods, such as displacement-time histories, Poincare maps, and phase diagrams. The responses are chaotic, but, not so sensitive to the initial conditions, and the characteristics of responses are not changed with time, in contrast to the case of the responses of beam. The Poincare points scattered in the limited area represent that the responses are chaotic, but do not show the geometric structures. The snap-through phenomena of the shell to the side of the direction of the load or of the opposite direction, is analysed by using the energy diagram.

• Korean Journal of Construction Engineering and Management
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• v.5 no.3 s.19
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• pp.71-78
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• 2004

In conventional method of supporting soil shuttering wall during excavation a system of struts and wales to provide cross-lot bracing is common in trench excavations and other excavations of limited width. This method, however, becomes difficult and costly to be adopted for large excavations since heavily braced structural systems are required. Another expensive and unsafe situations are expected when temporary struts must be removed for the construction of underground structures. This paper introduces innovative strut systems which can be used as permanent underground structures after its role as brace system to resist earth pressure during excavation phase. Underground structural system suggested from architect is checked against the soil lated pressures before the analysis of stresses developed from gravity loads. In this technology, named SPS(Struts as Permanent System), retaining wall is installed first and excavation proceeds until the first level of bracing is reached. Braces used as struts during excavation will serve as permanent girders when buildings are in operation. Simultaneous construction of underground and superstructure can proceeds when excavation ends with the last level of braces being installed. In this paper, construction sequence and the calculation concept are explained in detail with some photo illustrations. SPS technology was applied to three selected buildings. One of them was completed and two others are being constructed Many sensors were installed to monitor the behavior of retaining wall, braces as column in terms of stress change and displacement. Adjacent ground movement was also obtained. These projects demonstrate that SPS technology contributes to the speed as well as the economy involved in construction.

• The Korean Journal of Health Service Management
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• v.6 no.2
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• pp.211-217
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• 2012

To identify health behavior of Peptic ulcer patients among all employees in Korea and examine relevant factors to present basic data for improving Korean adult employees' health conditions and quality of living, 3,515 employees aged 20 to 69 were sampled from the group that responded to the question concerning the presence of Peptic ulcer in the fourth Korea National Health and Nutrition Examination Survey for the third year (2009). After logistic regression analysis was carried out to see the effects of working conditions, harmful factors, shift work, stress perception, and experience of depression on the presence of Peptic ulcer, it was found that unsafe or unpleasant working conditions led to higher risk of getting Peptic ulcer, that flexible workers were more likely to get Peptic ulcer, and that depression or stress perception exerted almost no effect on Peptic ulcer. With the increase in the number of flexible workers, increasingly more interest is taken in the effects of shift work on health; occupational Peptic ulcer tends to become chronic as compared with the condition in the general population and reappear even after recovery in many cases; therefore, it is necessary to take special management measures by estimating the number of those at a risk of getting Peptic ulcer and by finding out its risk factors.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.1
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• pp.94-101
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• 2018

With the development of industrial technology and science, production and manufacturing facilities have been enhanced and improved, and the importance of the safety of workers has also been regulated and limited by various safety management methods. As a way to secure the safety of the workers from the production facility, the fail-safe and fool-proof methods are now being applied. Any possible insecure behavior and unsafe conditions can be removed by adopting the standards and specifications that are now secure the safety of workers and equipment. This research analyzes EN ISO 13849-1 international and European standards during CE certification. In order to secure acceptable reduced risks, the risk assessment process of ISO 12100 and the processes for reducing its risk are applied. In the current ISO 13849-1 standard, the criteria for the required performance level PLr (Required Performance Level) for the applicable risk and safety functions through the risk assessment are subjective and not subdivided. Therefore, the evaluation criteria are likely to cause judge's judgement error due to qualitative judgement. This research focuses on evaluation and acceptable performance level setting for the safety circuit of the equipment. We propose an objective and specific evaluation criteria to secure safety, and the proposed evaluation criteria are applied to the case study of the safety circuit for the equipment. In order to secure the safety of the entire safety circuit, the improvement of the MTTFd and DC level related to the SRP/CS (Safety-Related Parts of Control Systems)' lifetime is required for the future research.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.712-718
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• 2015

Cast duplex stainless steels are susceptible to thermal aging during long-term service at temperatures ranging from $280^{\circ}C$ to $450^{\circ}C$. To analyze the effect of thermal aging on leak-before-break (LBB) behavior, three-dimensional finite element analysis models were built for circumferentially cracked pipes. Based on the elasticeplastic fracture mechanics theory, the detectable leakage crack length calculation and J-integral stability assessment diagram approach were carried out under different bending moments. The LBB curves and LBB assessment diagrams for unaged and thermally aged pipes were constructed. The results show that the detectable leakage crack length for thermally aged pipes increases with increasing bending moments, whereas the critical crack length decreases. The ligament instability line and critical crack length line for thermally aged pipes move downward and to the left, respectively, and unsafe LBB assessment results will be produced if thermal aging is not considered. If the applied bending moment is increased, the degree of safety decreases in the LBB assessment.