• Safety and Health at Work
• /
• v.6 no.2
• /
• pp.134-138
• /
• 2015

Background: Noise-induced hearing loss (NIHL) is a major preventable occupational health problem with 250 million people worldwide known to have disabling impairment of moderate to greater severity. The aims of the study are to estimate the prevalence of NIHL in the police force; and study its association with age, sex, duration of service (years), smoking and alcohol habits, use of hearing protective devices, as well as preexisting chronic diseases. Methods: A cross-sectional study was conducted on 543 police personnel who had undergone periodic medical examination over a 12-month period. The diagnostic criteria for NIHL were (1) history of occupational noise exposure, (2) bilateral hearing loss, (3) hearing loss of ${\geq}25dBA$ at 4,000 Hz in two consecutive audiograms, and (4) no significant medical history affecting hearing. Severity of NIHL was based on the World Health Organization grading. Results: Males (74.8%) made up the majority of the police force. The mean age for police personnel was $35.55{\pm}9.57years$, and the mean duration of service was $14.75{\pm}9.39years$. Compliance with the usage of hearing protective devices was seen in 64.4%. The prevalence of NIHL in this study population was 34.2%, with a higher prevalence in males (37.7%) than in females (23.9%). The study also showed strong associations between NIHL and male sex (odds ratio, 1.9; P < 0.05), and hypertension (odds ratio, 3.3; P < 0.001). Overall, 93% were found to have mild NIHL, 3.5% had moderate NIHL, and 3.5% had severe NIHL. No police personnel were found to have profound hearing loss. Conclusion: The prevalence of NIHL in this study is high compared to other similar studies among police personnel. This study shows that increasing age, male, presence of hypertension, diabetes, and longer duration of service are significant associated factors for NIHL. Preventative strategies include health surveillance, implementation of a hearing conservation program, and legislation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.2
• /
• pp.634-643
• /
• 2010

In this study, both an experimental test and a time history analysis with 3D modeling were performed to verify the structural analysis model in a 2-span two girder bridge of high speed railway, which was under constructed according to the ballast load of track structure. In the basis of the structural analysis model, the analysis of construction step was carried out to investigate the reduction effect of moment in middle support of the bridge which has initial prestressing force according to camber control. The initial prestressing force of proper level was calculated, and then the reduction of moment for economical bridge section was studied. Finally, a bridge analysis method was presented for an economical and efficient design in steel composite bridge.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.7 no.2
• /
• pp.289-297
• /
• 1997

Work-related low back pain(below LBP) is one of the major cause of morbidity, disability, limitation of activity and economic loss. Therefore the work-related LBP is one of the major issue in the field of industrial safety and health. This study was performed for detecting the risk factors and proposing the effective control programs of work-related LBP. The subjects were male workers employed at the welding and metal factory. The data was collected by self-reported questionnaire, interview and checking abdomen muscular and grasping power for two days on October, 1993. The contents of questionnaire were as follow: the experience of LBP, general characteristics, physical characteristics, employment status, type of work and working environment. The number of cases was 104 with a history of work-related LBP, so the prevalence of work-related LBP was 35.0%, and the number of controls was 140 without any history of LBP. As a result, marital status, educational level, abdomen muscular power, tenure, category of job, satisfaction of job, working posture, satisfaction for table and chair and lifting materials showed a statistical significance between the case and control groups. 284 Lifting jobs were quantified by NIOSH lifting equation method and ergonomic computer modelling methods. There were no significant differences in the action limit and disc compression force between group with LBP and without LBP. But in the lifting frequency and cumulative disc compression force there were significant differences. Therefore work-related LBP should be prevented by the ergonomic and environmental control.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.22 no.5
• /
• pp.299-309
• /
• 2018

Now that problems with force-based seismic design have been clearly identified, design is inclined toward displacement-based methods. One such widely used method is Direct-Displacement-Based Design (DDBD). Yet, one of the shortcomings of DDBD is considering higher-mode amplification of story shear, moments, and displacements using equations obtained from limited parametric studies of regular planar frames. In this paper, a different approach to account for higher-mode effects is proposed. This approach determines the lateral secant stiffness of the building frames that fulfill the allowable inter-story drift without exceeding the desired story displacements. Using the stiffness, an elastic response spectrum analysis is carried out to determine elastic higher-mode force effects. These force effects are then combined with DDBD-obtained first-mode force effects using the appropriate modal superposition method so that design can be performed. The proposed design procedure is verified using Nonlinear Time History Analysis (NTHA) of twelve planar frames in four categories accounting for mass and stiffness irregularity along the height. In general, the NTHA response outputs compared well with the allowable limits of the performance objective. Thus, it fulfills the aim of minimizing the use of NTHA for planar frame buildings, thereby saving computational resources and effort.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.6
• /
• pp.503-511
• /
• 2004

In this study, for estimating responses of a controlled structure and determining the maximum control force of velocity-dependent damping devices, three estimation models such as Fourier envelope convex model, probability model, and Newmark design spectrum are used. For this purpose, a procedure is proposed for estimating actual velocity using pseudo-velocity and this procedure considers the effects of damping ratio increased by the damping device. Time history results indicate that actual velocity should be used for estimating accurate maximum control force of damping device and Newmark design spectrum modified by the proposed equation gives the best estimation results for over all period structures.

• Structural Engineering and Mechanics
• /
• v.77 no.6
• /
• pp.721-734
• /
• 2021

The seismic analysis of structures without applying the effects of soil can undermine functional objectives of structure so that it can affect all the desired purposes at the design and control stages of the structure. In this research, employing OpenSees and MATLAB software simultaneously and developing a definite three-dimensional finite element model of a high-rise concrete structure, designed using performance-based plastic design approach, the performance of Tuned Mass Damper (TMD) and Active Mass Damper (AMD) is both examined and compared. Moreover some less noted aspects such as nonlinear interaction of soil and structure, uplift, nonlinear behavior of structure and structural torsion have received more attention. For this purpose, the analysis of time history on the structural model has been performed under 22 far-field accelerogram records. Examining a full range of all structural seismic responses, including lateral displacement, acceleration, inter-story drift, lost plastic energy, number of plastic hinges, story shear force and uplift. The results indicate that TMD performs better than AMD except for lateral displacement and inter-story drift to control other structural responses. Because on the one hand, nonlinear structural parameters and soil-structure interaction have been added and on the other hand, the restriction on the control force applied that leads up to saturation phenomenon in the active control system affect the performance of AMD. Moreover, the control force applied by structural control system has created undesirable acceleration and shear force in the structure.

• Earthquakes and Structures
• /
• v.26 no.3
• /
• pp.229-237
• /
• 2024

This paper studied the subgrade spring stiffness and its influencing factors in the seismic deformation method of circular tunnel. Numerical calculations are performed for 3 influencing factors: stratum stiffness, tunnel diameter and burial depth. The results show that the stratum stiffness and tunnel diameter have great influence on the subgrade spring stiffness. The subgrade spring stiffness increases linearly with stratum stiffness increasement, and decreases with the tunnel diameter increasement. When the burial depth ratio (burial depth/tunnel diameter) exceeds to 5, the subgrade spring stiffness has little sensitivity to the burial depth. Then, a proposed formula of subgrade spring stiffness for the seismic deformation method of circular tunnel is proposed. Meanwhile, the internal force results of the seismic deformation method are larger than that of the dynamic time history method, but the internal force distributions of the two methods are consistent, that is, the structure exhibits elliptical deformation with the largest internal force at the conjugate 45° position of the circular tunnel. Therefore, the seismic deformation method based on the proposed formula can effectively reflect the deformation and internal force characteristics of the tunnel and has good applicability in engineering practice.

• Journal of the military operations research society of Korea
• /
• v.37 no.1
• /
• pp.27-38
• /
• 2011

Purpose that studies the war history is to prevent the war in the advance through instruction that is gotten by understanding the past war and in case of emergency, it is to win victory in the war from the enemy by doing not commit a same mistake like the past war. For these reasons, many studies about the war history have proceeded continuously in domestic and outside the country, and those are being carried out in present. However, most of studies of the war history have been analyzed only on qualitative analysis. In this study, we want to suggest quantitative analysis method using simulation with qualitative analysis. As an example of study, we quantitatively analyzed the importance of logistics support on the Moscow expedition of Napoleon. Also, on the basis of this, we found failure factor of logistics support of Napoleon force and through this, deduced instruction. There is meaning that this paper suggested quantitative analytical method in terms of study of the war history with qualitative analytical method.

• Journal of Korean Academy of Nursing Administration
• /
• v.8 no.3
• /
• pp.373-380
• /
• 2002

Purpose : The purpose of this study is to analyze the history of nursing and medicine as phenomena of knowledge/power from the viewpoint of Foucault. Method : The present study adopts the genealogical method by Foucault, which tries to unite languages and knowledge. Foucault who attempted to show that the basic ideas which people normally take to be permanent truths about human nature and society change in the course of history. Results : It has been emphasized that the development of modern health care has been due to the progressive efforts of medicine and to medical discoveries. Foucault examines the institutionalization of knowledge and the power exerted thereby, with special reference to the devices of social regulation and their function over the madness, the disease, the crime, and the sexuality. The concept of power is that it is exerted spontaneously in verbal behaviors of individuals through knowledge of everyday life such as definition of body or mind. Therefore as to the problem of knowledge/power, this study tries to understand the meaning of history of nursing and medicine through an analysis of the formation of text of history. In order to have authority in a power relation, the medical professional asserts that medical discourse is the most scientific knowledge. Conclusion : According to the above findings, it can be concluded that the body is also directly invested in a political field: power relations have an immediate hold upon it; they invest it, mark it, train it, torture it, force it to carry out tasks, to perform ceremonies, to emit signs. Therefore the devaluation of nursing care is reinforced by the medicine which has the legitimate authority through use of the political skills about the body.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.13 no.1
• /
• pp.35-43
• /
• 2009

Two types of piloti-type high-rise RC building structures having irregularity in the lower two stories were selected as prototypes, and nonlinear time history analysis was performed using OpenSees to verify the analysis technique and to investigate the seismic capacity of those buildings. One of the buildings studied had a symmetrical moment-resisting frame (BF), while the other had an infilled shear wall in only one of the exterior frames (ESW). A fiber model, consisting of concrete and reinforcing bar represented from the stress-strain relationship, was adapted and used to simulate the nonlinearity of members, and MVLEM (Multi Vertical Linear Element Model) was used to simulate the behavior of the wall. The analytical results simulate the behavior of piloti-type high-rise RC building structures well, including the stiffness and yield force of piloti stories, the rocking behavior of the upper structure and the variation of the axial stiffness of the column due to variation in loading condition. However, MVLEM has a limitation in simulating the abrupt increasing lateral stiffness of a wall, due to the torsional mode behavior of the building. The design force obtained from a nonlinear time history analysis was shown to be about $20{\sim}30%$ smaller than that obtained in the experiment. For this reason, further research is required to match the analytical results with real structures, in order to use nonlinear time history analysis in designing a piloti-type high-rise RC building.