• Wind and Structures
• /
• v.28 no.4
• /
• pp.203-213
• /
• 2019

The topography and geomorphology are complex and changeable in western China, so the railway transition section is common. To investigate the aerodynamic effect of the subgrade-tunnel transition section, including a cutting-tunnel transition section, an embankment-tunnel transition section and two typical scenarios for rail infrastructures, is selected as research objects. In this paper, models of standard cutting, embankment and CRH2 high-speed train with the scale of 1:20 were established in wind tunnel tests. The wind speed profiles above the railway and the aerodynamic forces of the vehicles at different positions along the railway were measured by using Cobra probe and dynamometric balance respectively. The test results show: The influence range of cutting-tunnel transition section is larger than that of the embankment-tunnel transition section, and the maximum impact height exceeds 320mm (corresponding to 6.4m in full scale). The wind speed profile at the railway junction is greatly affected by the tunnel. Under the condition of the double track, the side force coefficient on the leeward side is negative. For embankment-tunnel transition section, the lift force coefficient of the vehicle is positive which is unsafe for operation when the vehicle is at the railway line junction.

• Journal of the Korean Society of Safety
• /
• v.34 no.1
• /
• pp.45-52
• /
• 2019

Accident analysis models were developed to improve the construction site safety and case studies was conducted. In 2016, 86% of fatality accidents occurred due to simple unsafe acts. Structure related accidents are less frequent than the non structure related causes, but the number of casualties per accident is two times higher than non structure one. In the view of risk perception, efforts should be given to reduce accidents caused by low frequency - high consequence structure related causes. In case of structure related accident, structural safety inspection and management (including quality), ground condition management / inspection technology, and provision of risk information delivery system in case of non structure related accident were proposed as a solution. In analysis of relationship between safety related stakeholder, the main problem were the lack of knowledge of controller and player, loss of control due to duplicated controls, lack of communication system of risk information, and relative position error of controller and player.

• Journal of the Korean Society of Safety
• /
• v.36 no.2
• /
• pp.18-25
• /
• 2021

Specialty contractor facilities, which involve a combination of welding and commissioning, face a high risk of serious accidents such as fire, explosion, and suffocation associated with welding work, nitrogen, and argon use. In such facilities, the organizational safety culture has considerable impact on the frequency of accidents. In this study, a safety culture evaluation was conducted on specialty contractors. NOSACQ-50, a standardized survey method on safety culture, was selected as an assessment tool to evaluate the safety culture in specialized construction companies that could not afford to invest heavily in safety. The self-administered questionnaire survey was conducted with 201 workers of four construction companies and the results were analyzed. It was found that in companies with low safety culture, the occurrence of irrationality was 66.0%, while in companies with high safety culture, the occurrence of irrationality was 42.6%. Thus, the difference in the occurrence of irrationality by safety culture was statistically significant. The difference in safety culture level according to the experience of occurrence of irrationality was also significant. It was also found that the higher the belief in safety management authorization, safety responsibilities of managers, worker safety priorities, and safety system effects, the lower the probability of irrationality.

• Korean Journal of Construction Engineering and Management
• /
• v.19 no.6
• /
• pp.55-64
• /
• 2018

In spite of many previous studies conducted to prevent safety accidents at construction sites, the frequency of safety accidents has not decreased. And recently, a lot of research has been done to analyze the causes of the accidents resulting from the personal characteristics and behaviors of managers or workers, and eliminate them. However, despite these efforts, safety accidents occur consistently as managers and workers shift their responsibilities for the safety accidents onto someone other than themselves. Therefore, in order to prevent safety accidents, this study investigated the consciousness of shifting responsibility among managers and workers and analyzed the correlation between factors influencing the consciousness of shifting responsibility. In addition, it proposed the quantitative levels of the consciousness of shifting responsibility based on the survey of managers and workers. The results of this study demonstrated that managers tend to the shift responsibility onto workers, whereas workers the shift responsibility onto managers. It was additionally demonstrated that there is a correlation between the consciousness of shifting responsibility and the factors influencing it. The findings of this study are expected to improve the safety awareness among managers and workers and make contributions in the theoretical and practical aspects of construction safety management.

• Korean Security Journal
• /
• no.16
• /
• pp.321-338
• /
• 2008

Soongrae-Mun Fire shows safety problem in Korea intimately. People have pressed for the responsibility of persons in charge and have asked for improvement measure whenever Fire accident occur, but similar accidents occur again without any improvement. This research is to provide improvement. measure on the base of the analysis of the cause of Soongrae-Mun fire to prevent similar accident, also to help private security company do effective security job. This research is approached from a security point of view. A lot of accidents occur by direct cause such as people's unsafe action and unsafe condition. but it is very difficult to remove the facts of direct cause, so the facts of indirect cause should be analyzed together. Drew-up of security related legislation should be included when the establishment of fire fighting related legislation is examined, also technical improvement should be examined with legislation. security company should be concerned about securing of expertise and reinvestment for the improvement of expertise to overcome limitations of private security such as job boundary, capability and responsibility. Also private security company should try to service for public benefit and to examine practical compensation for loss occurred by mistake of security company.

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

• Journal of Korea Water Resources Association
• /
• v.30 no.6
• /
• pp.691-698
• /
• 1997

The risk assessment model for dam and levee is applied to a river where two adjacent dams are located in the upstream of the watershed. "A" dam is proven to be safe with 200-year precipitation and unsafe with PMP condition, whereas "B" dam to be safe with 200-year precipitation and PMP condition. The computed risk considering the uncertainties of the runoff coefficient. initial water depth and relevant data of the dam and spillway turn out to be equivalent results in Monte-Carlo and AFOSM method. In levee risk model, this study addresses the uncertainty of water surface elevation by Manning's equation. Monte-Carlo simulation with the variations of Manning's roughness coefficient is calculated by assuming that it follows atriangular distribution. The model can be used for preparing flood risk maps, flood warning systems, and establishing nation's flood disaster protection plan.

• KCID journal
• /
• v.19 no.1
• /
• pp.64-76
• /
• 2012

Recently, it has been increased disaster of crops and agricultural facilities with climate change such as regional storm, typhoon. However agricultural facilities have unsafe design criteria of improving drainage corresponding to this change. This study has analyzed the impact that inundation area and magnitude of drainage-facility is decided based on fixed- and unfixed-duration precipitation by applying revised design criteria of drainage for climate change. The result was shown that 1-day and 2-days rainfall for 20-years return period has increased about 11.4%, 4.4% respectively by changing fixed- to unfixed duration. And the increase rate of design flood was 15.0%. The result was also shown that Inundation area was enlarged by 6.6% as well as increased inundation duration under same basic condition in designed rainfall between fixed- and unfixed-duration. According to the analysis, it is necessary for pump capacity in unfixed-duration to be increased by 70% for same effect with fixed-duration. Therefore, when computing method of probability precipitation is changed from fixed one to unfixed-duration by applying revised design criteria, there seems to be improving effect in drainage design. Because 1440-minutes rainfall for 20-years return period with unfixed-duration is more effective than 1-day rainfall for 30-years return period with fixed-duration. By applying unfixed-duration rainfall, capacity of drainage facilities need to be expanded to achieve the same effects (Inundation depth & duration) with fixed-duration rainfall. Further study is required for considering each condition of climate, topography and drainage by applying revised design criteria.

• Korean Journal of Construction Engineering and Management
• /
• v.7 no.4 s.32
• /
• pp.61-68
• /
• 2006

Safety is the most important issue in the construction industry. Especially, work-related disease is increasing and resulted in lack of young workers and high turnover due to its 3D industrial image. The main objective of this paper is to identify the relationship of WRMSD with hand tools used in the building construction industry. In order to reach to the goals, the survey and interviews with laborers are conducted. The data is analyzed in a statistical manner. One of the interesting findings from the research is that the carpenters and steelworkers are the principal trade group suffering from WRMSD due to unsafe working condition and method. The results of the research will be used as the basis for the ergonomic design of the better construction working condition and hand tools.

• Smart Structures and Systems
• /
• v.24 no.5
• /
• pp.669-681
• /
• 2019

Bridge collapses may deliver a huge impact on our society in a very negative way. Out of many reasons why bridges collapse, poor maintenance is becoming a main contributing factor to many recent collapses. Furthermore, the aging of bridges is able to make the situation much worse. In order to prevent this unwanted event, it is indispensable to conduct continuous bridge monitoring and timely maintenance. Visual inspection is the most widely used method, but it is heavily dependent on the experience of the inspectors. It is also time-consuming, labor-intensive, costly, disruptive, and even unsafe for the inspectors. In order to address its limitations, in recent years increasing interests have been paid to the use of unmanned aerial vehicles (UAVs), which is expected to make the inspection process safer, faster and more cost-effective. In addition, it can cover the area where it is too hard to reach by inspectors. However, this strategy is still in a primitive stage because there are many things to be addressed for real implementation. In this paper, a typical procedure of bridge inspection using UAVs consisting of three phases (i.e., pre-inspection, inspection, and post-inspection phases) and the detailed tasks by phase are described. Also, three major challenges, which are related to a UAV's flight, image data acquisition, and damage identification, respectively, are identified from a practical perspective (e.g., localization of a UAV under the bridge, high-quality image capture, etc.) and their possible solutions are discussed by examining recently developed or currently developing techniques such as the graph-based localization algorithm, and the image quality assessment and enhancement strategy. In particular, deep learning based algorithms such as R-CNN and Mask R-CNN for classifying, localizing and quantifying several damage types (e.g., cracks, corrosion, spalling, efflorescence, etc.) in an automatic manner are discussed. This strategy is based on a huge amount of image data obtained from unmanned inspection equipment consisting of the UAV and imaging devices (vision and IR cameras).