• Journal of the Korea Safety Management & Science
• /
• v.26 no.2
• /
• pp.87-92
• /
• 2024

This study aims to compare six observational methods for assessing arm- and hand-intensive tasks, based on literature review. The comparison was conducted in viewpoints of body regions, force/external load, motion repetition, other factors including static posture, coupling, duration/break, pace, temperature, precision task, and final risk or exposure level. The number of risk factors assessed was more, and assessment procedure was more complex than the observational methods for assessing whole-body postural loads such as Ovako Working Posture Analysis System(OWAS), Rapid Upper Limb Assessment(RULA), and Rapid Entire Body Assessment(REBA). Due to these, the intra- and inter-reliabilities were not high. A past study showed that while Hand Arm Risk Assessment Method(HARM) identified the smallest proportion of the work tasks as high risk, Strain Index(SI) and Quick Exposure Check(QEC) hand/wrist were the most rigorous with classifying most work tasks as high risk. This study showed that depending on the observational technique compared, the evaluation factors, risk or exposure level, and evaluation results were different, making it necessary to select a technique appropriate for the characteristics of the work being assessed.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.24 no.3
• /
• pp.371-382
• /
• 2014

Objectives: This study was undertaken in order to examine how musculoskeletal disorder(MSD) symptoms were affected by particular factors and then to explore control strategies to prevent MSDs in general hospital nurses. Materials: This, as part of a large study, was conducted using a set of information on literature review, questionnaire survey and focus group interview. It obtained prevalence and factors of MSD symptoms and examined how MSD symptoms were distributed and affected by the factors in nurses working at 15 general hospitals across Korea. The factors were personal factors, work organization, nursing tasks, physical factors and psychosocial factors. Results: A total of 501 nurses were determined as subjects. The highest MSD symptom prevalence was 61% for the shoulder, among body parts, followed by leg/feet(55%), low back(51%), neck(42%), wrist(38%), and elbow(21%). Prevalence for the whole body was 80%. Odds ratios ranged from 0.4 to 22.4 in logistic regression analyses. The symptoms were significantly attributed to factor variables such as body mass index, current health status, daily work time, nursing task, pooled-physical factors, ergonomic factors, work load, interpersonal conflict, and job insecurity. Conclusions: Two or more factor variables were significant, depending on body part, for MSD systems in the general hospital nurses. It was noticeable that physical factors, such as pooled-physical factors, ergonomic factors or work load, were selectively significant for MSD symptoms in all body parts, indicating that such information should be used for prevention of MSDs in the hospital sector.

• Nuclear Engineering and Technology
• /
• v.49 no.3
• /
• pp.476-483
• /
• 2017

The decay heat that is produced by nuclear reactor spent fuel must be cooled in a spent fuel storage pool. A wickless heat pipe or a vertical two-phase closed thermosyphon (TPCT) is used to remove this decay heat. The objective of this research is to investigate the thermal performance of a prototype model for a large-scale vertical TPCT as a passive cooling system for a nuclear research reactor spent fuel storage pool. An experimental investigation and numerical simulation using RELAP5/MOD 3.2 were used to investigate the TPCT thermal performance. The effects of the initial pressure, filling ratio, and heat load were analyzed. Demineralized water was used as the TPCT working fluid. The cooled water was circulated in the water jacket as a cooling system. The experimental results show that the best thermal performance was obtained at a thermal resistance of $0.22^{\circ}C/W$, the lowest initial pressure, a filling ratio of 60%, and a high evaporator heat load. The simulation model that was experimentally validated showed a pattern and trend line similar to those of the experiment and can be used to predict the heat transfer phenomena of TPCT with varying inputs.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.18 no.4
• /
• pp.16-25
• /
• 2019

Recently, due to labor shortages in rural areas within South Korea, the demand for upland-field machinery is growing. In addition, there is a lack of development of systematic performance testing of upland-field machinery. Thus, this study examined structural safety and drawbar pull based on soil properties, as a first step for systematic performance testing on the test bed. First, the properties of soil samples from 10 spots within the experimental site were examined. Second, the strain was measured and converted into stress on 8 points of an onion harvester that are likely to fail. More specifically, the chosen parts are linked to the power, along with the drawbar pull, using a 6-component load cell equipped between the tractor and the onion harvester. The water content of the soil ranged between 5.7%-7.5%, and the strength between 250-1171 kPa. The test soil was subsequently classified into loam soil based on the size distribution ratio of the sieved soil. The onion harvester can be considered as structurally safe based on the derived safety factor and the drawbar pull of 115-1194 kgf, according to the working speed based on agricultural fieldwork.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.4
• /
• pp.468-475
• /
• 2019

An end-line flame arrester allows free venting in combination with flame protection for vertical vent applications. End-line flame arresters are employed in various fields, especially in shipping. In flame arresters, springs are essential parts because the spring load and the spring's elasticity determine the hood opening moment. In addition, the spring has to work under a high-temperature condition because of the burning gas flame. Therefore, it is necessary to analyze the mechanical load and elasticity of the spring when the flame starts to appear. Based on simulations of the working process of a specific end-line flame arrester, a thermal and structural analysis of the spring is performed. A three-dimensional model of a burned spring is built using computational fluid dynamics (CFD) simulation. Results of the CFD analysis are input into a finite element method simulation to analyze the spring structure. The research team focused on three cases of spring loads: 43, 93, and 56 kg, correspondingly, at 150 mm of spring deflection. Consequently, the spring load was reduced by 10 kg after 5 min under a $1,000^{\circ}C$ heat condition. The simulation results can be used to predict and estimate the spring's load and elasticity at the burning time variation. Moreover, the obtained outcome can provide the industry with references to optimize the design of the spring as well as that of the flame arrester.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.11
• /
• pp.1667-1674
• /
• 2010

The fatigue life is estimated while determining the reliability of aircraft structures. In this study, the estimation of fatigue life was carried out on the basis of a cumulative damage theory; the working S-N curve and the equivalent stress on the engine support structure significantly affect the safety of the aircraft. The maximum stress observed was 1,080 MPa in the case of scissors link under crash load condition, and there was a 5% margin for the allowable stress corresponding to the temperature reduction factor. The maximum stress was 876 MPa, and the stress equation coefficient had a maximum value of 0.019 MPa/N in the case of scissors link under fatigue loads. In the results of the fatigue life analysis, the safety life in a fretting area of scissors link upper part was 416,667 flight hour, and other parts showed to infinite life. Therefore, it was demonstrated that the fatigue life requirement of aircraft engine support structure (scissors link, straight link) could be satisfied.

• Safety and Health at Work
• /
• v.11 no.4
• /
• pp.543-549
• /
• 2020

Background: The working conditions of bus drivers are difficult; they lead to occupational diseases and require careful study, particularly in Ukraine. The objective of the article is the description of occupational health risks of passenger bus drivers that lead to deteriorating health. Methods: The risk assessment was performed using a modified Risk Score method, which allowed determining the generalized level of danger to the driver's health. The hygienic hazards level was assessed as based on Stevenson's law, which was generalized later. Results: Based on the modification of the Risk Score method, it was possible to depart from expert assessments method of the risk level and calculate the general indicator based on the degree of dependence of the impact on the human body on its intensity, proposed by V. Minko. This allows objective determining of the impact of hygiene hazards on the health of the driver and to predict the occurrence of occupational diseases associated with the cardiovascular system, musculoskeletal system, and partial or complete disability due to the accumulation of emotional fatigue. The hazard assessment was carried out for three brands of passenger buses common in Ukraine, in which the driver is exposed to the dangers of fever, vibration, noise, harmful impurities in the bus cabin, and emotional load. Conclusion: The health of drivers in the cabins of passenger buses is most affected by hygiene hazards: fever, vibration, and emotional stress. The generalized level of risk is calculated by the modified method of Risk Score is 0.83; -0.99, -0.92 respectively.

• Journal of The Korean Society For Urban Railway
• /
• v.6 no.4
• /
• pp.249-257
• /
• 2018

The number of deaths for railway traffic accidents is mainly caused by working close to the track, or when unauthorized passage pass through the track. The safety fences are being used to ensure safety for workers close to the track, and to improve the efficiency of the work, without interfering with the passage of trains. However, a safety fence for railway tracks needs to be examined to see if it will interfere with the passage of trains. The purpose of this study is to analyze the safe distance between train and safety fence developed in Korea. In addition, the lateral load condition of wind pressure by trains is estimated and numerical analysis is carried out according to the installation intervals of railway safety fences. It has been confirmed that the proper spacing between the train and the railway safety fence should be at least 200 mm from the vehicle limit, and that the proper spacing of railway safety fence must be calculated in consideration of the wind pressure by trains.

• Journal of the Korean Society of Safety
• /
• v.24 no.6
• /
• pp.136-143
• /
• 2009

The injuries as a result of fall accidents is the one of the most common kind of injuries in Korea, especially fall from height is the top most common kind for fatal injuries. Futhermore, the number of fall injuries in manufacturing industry has been steadily increasing from 2000 to 2007. In 2007 the number of fall fatal injuries increased 10.6 % in comparison with the number in 2006. These numbers are 6~17 times higher than those for foreign countries such as the U.K and the USA. So, it is needed to make a study to reduce these numbers for manufacturing industry. To get the goals, we did research as followings. First, this study analyzed statistics by industry, by fall height, by common agent and so on to gain an insight into real aspect of fall injuries. It showed that ladder is the commonly cited agent for manufacturing industry, and 3 risky activities ; the ladder work, the load/unload work, and the maintenance work. Secondly, this study made a survey of manufacturing workers for their understandings of the most 3 risky activities. It showed that 'tendency to work easily' and 'difficulty of applying measures due to inherent working conditions' are main reasons for workers not to implement the preventive measures against the fall accidents. Thirdly, this study tested the slip characteristics of ladder base and lungs. The tests were done based on ANSI standard and KS. In addition to the standard condition, this study performed slip tests in wet and sandy conditions and compared the results with the those of standard condition. It showed that friction coefficient is standard condition > wet condition > sandy condition, and the friction coefficient of ladder for sandy condition is measured to be reduced by 63.9% compared with that for standard condition. Finally, this study developed safety work models for using of portable ladders in consideration of the safety standards of foreign countries such as the U.K, the USA, and the Australia.

• Journal of the Ergonomics Society of Korea
• /
• v.29 no.3
• /
• pp.311-320
• /
• 2010

This study aimed to examine the development and characteristics of the workers with upper limb musculoskeletal symptoms and disorders and to analyze the upper limb musculoskeletal symptoms and disorders for its relationship with the individual socio-demographic characteristics. This study investigated the effect on the limitations of physical activities using standardized surveillance tool and clinical diagnosis. Musculoskeletal symptoms and the limitations of physical activities were examined. The clinical diagnosis of musculoskeletal disorders were carried out by physical examination, radiological examination and electromyography-electroneuronography for 22 workers in kitchen hood assembly process and 50 workers in toggle process of leather product manufacturing. The proportion of workers with musculoskeletal disorders was higher and the DASH score was also statistically higher in female and aged workers with longer working hours, longer household working hours, less leisure/hobby activity and higher physical load. Physical activities component score increased in the following order: workers in normal health, workers with musculoskeletal symptoms, and workers with musculoskeletal disorders as clinically diagnosed. Score for each DASH component increased in the following order: sports/performing arts ability, social activities, specific physical functional activities, work or other regular daily activities, work ability, psychological activities, insomnia and upper limb symptoms. The overall and each component DASH scores were higher in workers with symptoms of status praesens and of more severity, and receiving medical intervention. Musculoskeletal symptoms and disorders are associated with individual socio-demographic characteristics, and DASH score for physical activities of upper limb was higher in workers with musculoskeletal disorders. Musculoskeletal symptoms and disorders have a remarkable epidemiological significance for physical activities, social activities, work or other regular daily activities, upper limb symptoms and insomnia, where work ability, sports/performing arts ability and preventive measure is needed.