• International conference on construction engineering and project management
• /
• 2022.06a
• /
• pp.450-457
• /
• 2022

The construction industry is demanding, dynamic, and complex making it difficult for workers to recognize hazards. The nature of construction tasks exposes workers to several critical risk factors, such as a high rate of exertion and fatigue. Recent studies suggest that fatigue may impact hazard recognition in the construction industry. However, most studies rely on subjective measures when assessing the relationship between physical fatigue and hazard recognition, limiting such studies' efficacy. Thus, this study examined the relationship between physical fatigue and hazard recognition using a controlled experiment. Worker fatigue levels were captured using physiological data and a subjective exertion scale. The findings confirmed that physical exertion plays a significant role in hazard recognition skills (p < 0.05). This research contributes to theory and practice by providing a process for objectively assessing the influence of physical fatigue on worker safety and providing construction professionals with some critical insight needed to improve workplace safety.

• Safety and Health at Work
• /
• v.5 no.4
• /
• pp.191-197
• /
• 2014

Background: Disabling fatigue is common in the working age population. It is essential that occupational health (OH) professionals are up-to-date with the management of fatigue in order to reduce the impact of fatigue on workplace productivity. Our aim was to evaluate the impact of one-day workshops on OH professionals' knowledge of fatigue and chronic fatigue syndrome (CFS), and their confidence in diagnosing and managing these in a working population. Methods: Five interactive problem-based workshops were held in the United Kingdom. These workshops were developed and delivered by experts in the field. Questionnaires were self-administered immediately prior to, immediately after, and 4 months following each workshop. Questionnaires included measures of satisfaction, knowledge of fatigue and CFS, and confidence in diagnosing and managing fatigue. Open-ended questions were used to elicit feedback about the workshops. Results: General knowledge of fatigue increased significantly after training (with a 25% increase in the median score). Participants showed significantly higher levels of confidence in diagnosing and managing CFS (with a 62.5% increase in the median score), and high scores were maintained 4 months after the workshops. OH physicians scored higher on knowledge and confidence than nurses. Similarly, thematic analysis revealed that participants had increased knowledge and confidence after attending the workshops. Conclusion: Fatigue can lead to severe functional impairment with adverse workplace outcomes. One-day workshops can be effective in training OH professionals in how to diagnose and manage fatigue and CFS. Training may increase general knowledge of fatigue and confidence in fatigue management in an OH setting.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.9
• /
• pp.2271-2279
• /
• 1993

In the case of life prediction on the structures and machines after long service, it is natural to consider a degradation problems. Most of degradation data form practical structures are isolated data obtained at the time of periodical inspection or repair. From such data, it may be difficult to obtain the degradation curve available and necessary for life prediction. In this paper, for the purpose of obtaining a degradation curves, developed the simulate degradation method and fatigue test and Charpy impact test were conducted on the degraded, simulate degraded and recovered materials. Fatigue life prediction were conducted by using the relationship between fracture transition temperature (DBTT : vTrs) obtained from the Charpy impact test through the degradation process and fatigue crack growth constants of m and C obtained from the fatigue test.

• Journal of Environmental Health Sciences
• /
• v.36 no.5
• /
• pp.373-382
• /
• 2010

A number of recent studies have shown that occupational stress is closely associated with increased fatigue and decreased job satisfaction. This study was designed to assess stress in workers in the field of EIA (environment impact assessment) from July 2009 through september 2009, and questionnaires were uesd to analyze the stress scores and identify the primary factors influencing stress in this occupation. The number of respondents was 272 working in the Capital (Seoul and Kyunggido), Chungcheongdo, Jejudo area. A structured questionnaire was used to evaluate the participants' socio-demographics, job-related factors, health-related behaviors, occupational stress, reaction factor (self-perceived fatigue, job satisfaction) and buffer factor (social support). Occupational stress and self-perceived fatigue were assessed using the Korean Occupational Stress Scale-Short Form (KOSS-SF) and the Multidimensional Fatigue Scale (MFS), respectively. The analysis revealed a strong correlation between occupational stress, job satisfaction, and social support, with occupational stress being associated with an increased risk of fatigue and decreased job satisfaction. In the multiple regression analysis(stepwise), the main factors influencing occupational stress were found to be job satisfaction, supervisor, fatigue, working time, no. of personnel, career. The results of this study suggest that occupational stress is a determinant predictor of self perceived fatigue and job satisfaction. Thus, a strong recommendation is made for a stress management program for reduction of occupational stress, and for the development of relevant experts on the health and quality of life of environment impact assessment workers.

• Composites Research
• /
• v.13 no.1
• /
• pp.89-97
• /
• 2000

Fatigue damage detection and vibration sensing for a laminated composites and impact location detection for a steel beam have been carried out using optical fiber sensor. Intensity based optical fiber sensor is constructed by placing two cleaved fiber end in a hollow glass tube, and multiple reflection within the cavity is considered. Fatigue signals are measured by embedded optical fiber, surface mounted optical fiber sensor and strain gage simultaneously. For vibration sensing, optical fiber sensor is mounted on the carbon fiber composite beam and its response to free vibration and forced vibration is investigated. In impact location detection, two optical fiber sensors are used and the information obtained from two sensors is arrival time delay of vibration caused by impact. Impact location can be calculated from this time delay. The obtained results show that the intensity based optical fiber sensor provide reliable data during long-term fatigue loading, unlike strain gage which deteriorate during the early part of the fatigue test. Optical fiber sensor signals coincide with gap sensor in vibration sensing. The precise locations of impact can be detected within 4.1% error limit.

• Advances in concrete construction
• /
• v.12 no.5
• /
• pp.411-418
• /
• 2021

Roller compacted concrete (RCC) used in the island reef airport runway will be subjected to the coupling actions of the fatigue impacts and the salt spray cycles, which will accelerate the deterioration of runway concrete and even threaten the flight safety. A cyclic impact testing machine and a climatic chamber were used to simulate the low-velocity fatigue impact and the salt spray cycles, respectively. The physical properties, the microstructures and the porosity of RCC were investigated. The results show the flexural strength firstly increases and then decreases with the increase of the fatigue impacts and the salt spray cycles. However, the decrease in the flexural strength is significantly earlier than the compressive strength of RCC only subjected to the salt spray cycles. The chlorine, sulfur and magnesium elements significantly increase in the pores of RCC subjected to 30000 fatigue impacts and 300 salt spray cycles, which causes the decrease in the porosity of RCC. The coupling effects of the fatigue impacts and the salt spray cycles in the later period accelerates the deterioration of RCC.

• Journal of the Korean Society of Industry Convergence
• /
• v.7 no.2
• /
• pp.161-166
• /
• 2004

The impact factor of bridges is analyzed based on experimental data to examine the characteristics of the dynamic responses of bridges. The experimental impact factors are compared with the impact factor of Korean Highway Design Specification and Japan T-load in terms of the span length. According to the superstructural types of bridges, the variation of the impact factor is analyzed. When vehicles are passing on a bridge, the dynamic effect acts on the bridge impact factor more than at the time of design because of the velocity of vehicles, the surface roughness reduction due to the deterioration of the bridge deck pavement, and the disconnection of the bridge entrance and the expansion joint. Because the actual value is greater than the expected value at the time of design, the dynamic response of the bridge accelerates the deterioration of the bridge due to the accumulation of fatigue, and the bridge's life-time is shortened and can have an influence on the serviceability and safety of the bridge.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.6
• /
• pp.763-769
• /
• 2010

In recent times, there has been considerable interest in HIPS (High Impact Polystyrene) materials for their use in construction of office equipments, home electronics, housing for electronics appliances, packing containers, etc. However, these materials suffer from problems caused by fatigue fracture. Further, their strength is substantially affected by environmental conditions. Therefore, in this study, the effect of temperature was analyzed by performing a tensile test and a fatigue test. It was observed that the yield strength, the ultimate strength, and the fatigue life decreased relatively with an increase in temperature. Further, an S-N curve can be predicted by using the results of the tensile test and a micro-Vickers hardness test.

• Journal of Aerospace System Engineering
• /
• v.14 no.spc
• /
• pp.22-30
• /
• 2020

Composite rotor blades for rotorcraft have an intrinsic vulnerability to foreign object impact from its inherent structural characteristics of insufficient strength in the thickness direction, which may easily lead to internal structure damage. Therefore, defects and strength reducing effects caused by foreign object impact should be considered in fatigue evaluation of composite blades. For this purpose, the flaw tolerant safe-life and fail-safe concepts were adopted in fatigue evaluation since 1980s, and recently those concepts have been replaced by the damage tolerance concept. In this paper, the relevant standards for fatigue evaluation are analyzed focusing on fiber reinforced composite rotor blades used in rotorcraft. In addition, fatigue evaluation procedure of composite blades considering impact damages is proposed by reviewing the practices implemented through domestic development projects.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.8 s.179
• /
• pp.1910-1916
• /
• 2000

The five classes of the thermally aged CF8M specimen are prepared using an artificially accelerated aging method. Namely, after the specimens are held for 100, 300, 900, 1800, and 3600hrs at 430$^{\circ}C$ respectively, the specimens are water-cooled to room temperature. The impact energy variations are measures for both the aged and virgin specimens through the Charpy impact tests in addition to the microstructure observation, tensile, hardness and fatigue crack growth tests. From the present investigation the following results are obtained : 1) The difference among the thermally degraded specimens can be distinguished through their microstructures, 2) Hardness and tensile strength are increased to 300hrs, degradation specimen, while elongation and reduction area are decreased to 3600hrs degradation specimen, and impact energy is decreased to 1800hrs degradation specimen, 3) The FCG rates for thermally degraded specimens are larger than that of the virgin specimen.