• 한국심리학회지 : 문화 및 사회문제
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• 제12권3호
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• pp.23-47
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• 2006

본 연구에서는 연령에 따른 운전자의 운전확신수준 변화가 운전행동에 미치는 영향을 살펴보았다. 운전확신수준을 측정하기 위해 운전확신수준 설문지를 사용하였으며, 조사대상자들의 운전경력, 주행거리, 운전일수, 법규위반(음주, 과속), 교통사고경험(가해, 피해)을 함께 조사하였다. 조사대상자는 만 19세부터 만 80세까지였으며 총 1,055명이 연구에 참여하였다. 운전확신수준의 구조를 알아보고자 요인분석을 실시하였다. 각 연령(29세이하, 30-39세, 40-49세, 50-64세, 65세이상)의 운전확신수준을 비교하고, 운전확신수준과 운전행동과의 관계를 알아보았다. 그 결과, 운전확신수준은 '상황둔감성', '불안전운전', '주의집중소홀', '운전자신감'의 네 요인으로 이루어져 있었으며, 연령의 증가와 함께 운전확신수준은 감소하는 경향을 보였다. 또한, 운전확신수준은 연령과 가해교통사고, 피해교통사고, 운전기간, 음주운전, 과속운전, 운전경력 등과 상관관계를 가지고 있었다. 연구에 참여한 운전자 집단을 음주운전집단, 과속운전집단으로 나누어 운전확신수준과 운전행동의 차이를 알아보았는데, 음주운전이나 과속운전 경험이 없었던 운전자 집단과 음주운전이나 과속운전을 경험한 운전자 집단의 운전확신수준과 운전행동이 유의한 차이를 보이는 것으로 나타났다.

• 한국자동차공학회논문집
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• 제1권1호
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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.

• 여성건강간호학회지
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• 제14권3호
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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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• 제54권5호
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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.

• 한국건설관리학회논문집
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• 제20권6호
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• pp.66-73
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• 2019

정부와 안전보건공단의 재해 절감을 위한 다양한 노력덕분에 산업과 건설업 전반에 걸쳐 재해 사고는 감소추세를 보이고 있다. 하지만 건설업에서의 추락재해는 감소하지 않고 오히려 증가하고 있다. 특히, 달비계에 의한 추락재해는 매년 발생빈도는 낮지만 발생 시 작업자의 사망과 직결한다는 측면에서 재해강도가 매우 크다고 할 수 있다. 국내 건설업에서의 달비계 작업환경은 매우 열악하다. 특히 소규모 건설현장에서의 달비계 작업자들은 안전에 대한 감독과 관리를 받을 수 있는 주체가 없다. 달비계 작업자들은 자신들이 직접 제작한 성능이 확인되지 않은 달비계를 가지고 불안전한 작업환경에 내몰리고 있다. 따라서 본 연구는 15년간 달비계에서 기인한 242건의 사고사례들을 분석하여 추락재해 발생 주요 원인 및 개선방안을 제시하였으며, 주요내용은 불안전한 행동에 의한 재해발생률이 높아서 작업대 안착 시, 안전난간을 넘어가는 과정, 몸의 불균형 등에서 사고가 많으며 설비개선 및 작업방법개선으로 해결이 요구된다. 또한, KOSHA Guide에서 제시하는 작업순서 상의 문제점으로 발생되는 재해는 없었으며, 다만 작업 순서를 따르지 않아 안전대를 안전대 걸이용 로프에 미설치 및 미부착에 의한 사망으로 이르는 재해가 다수 발생된 것으로 파악되어 작업방법의 개선에서 가장 중요한 사항은 수직구명줄 및 안전대의 설치 및 착용이 가장 중요한 사항으로 도출되었다.

• 전산구조공학
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• 제10권3호
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• pp.167-174
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• 1997

계가 혼돈거동을 나타낼 경우에는 변수들의 미소변화에 의해서도 계가 전혀 다른 거동을 나타낼 수 있기 때문에 비선형계의 설계 및 해석시에는 이를 고려해야 한다. 따라서 본 연구에서는 구형 쉘의 중앙에 충격하중이 수직방향으로 작용하는 경우, 쉘의 기하학적 비선형성과 재료적 비선형성으로부터 기인되는 혼돈거동을 해석하였다. 쉘의 탄소성거동을 유한요소법을 이용하여 구한 후 계의 거동을 변위-시간이력, 프앙카레 맵, phase diagram등의 표준적인 방법들을 이용하여 쉘의 혼돈거동을 규명하였다. 해석결과, 계는 혼돈거동을 나타내었으나 탄소성보의 경우와는 달리 초기조건의 미소변화에 대한 극도의 민감도는 나타나지 않았으며 시간에 대한 쉘의 거동특성도 크게 변하지 않았다. 프앙카레 맵은 한정된 영역에 결쳐서 점들이 분포되었기 때문에 계의 거동이 혼돈거동임을 보여 주고 있지만 혼돈계의 프앙카레 맵에서 나타나는 기하학적 구조는 나타나지 않았다. 에너지선도를 이용하여 쉘이 하중의 작용방향 또는 반대방향으로 불규칙적으로 snap-through되는 원인을 규명하였다.

• 한국건설관리학회논문집
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• 제5권3호
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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.

• 보건의료산업학회지
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• 제6권2호
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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.

• 산업경영시스템학회지
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• 제41권1호
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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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• 제47권6호
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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.