• 대한안전경영과학회지
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• 제26권2호
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• pp.87-92
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• 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.

• 한국산업보건학회지
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• 제24권3호
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• pp.371-382
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• 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
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• 제49권3호
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• pp.476-483
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• 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.

• 한국기계가공학회지
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• 제18권4호
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• pp.16-25
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• 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.

• 해양환경안전학회지
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• 제25권4호
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• pp.468-475
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• 2019

엔드라인 폭연방지기는 수직 환기장치에 폭연방지와 함께 대기방출을 하도록 한다. 엔드라인 폭연방지장치는 선박과 같은 산업현장의 다양한 분야에 적용된다. 폭연방지기에서 스프링은 스프링 부하와 스프링의 탄성이 후드 개방 모멘트를 결정하므로 필수 부품이다. 더욱이, 장치 내 스프링은 고온의 상태에서도 작동해야 한다. 따라서, 폭연이 나타나기 시작할 때 스프링의 기계적 하중과 탄성을 분석할 필요가 있다. 이 연구에서는 엔드라인 폭연방지기의 작동 프로세스의 시뮬레이션을 기반으로 열 및 구조해석을 수행하으며, 스프링의 3차원 모델은 CFD 시뮬레이션을 이용하였다. CFD 해석은 FEM 시뮬레이션 값을 입력하여 스프링 구조를 분석한다. 본 연구에서는 스프링 부하의 43 kg, 93 kg 및 56 kg 세 가지 경우 즉, 150 mm 스프링 디플렉션에 부합하도록 집중적으로 관찰하였다. 결과적으로, $1,000^{\circ}C$ 가열조건 하에서 5분 후에 스프링 부하가 10 kg 감소했다. 시뮬레이션 결과는 연소 시간 변화에 따라 스프링의 부하와 탄성을 예측하고 추정할 수 있었다. 또한, 연구의 결과는 폭연방지기의 제조자들에게 역화방지장치뿐만 아니라 스프링의 설계를 최적화하기 위한 참고 자료로 활용할 수 있다.

• 대한기계학회논문집A
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• 제34권11호
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• pp.1667-1674
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• 2010

항공기 구조는 신뢰성 보장을 위해 피로하중에 대한 수명예측이 중요한 분야로 고려되고 있다. 본 논문에서는 항공기 비행안전과 가장 밀접한 엔진 지지구조물을 대상으로 S-N 곡선과 등가응력을 이용하여 선형누적손상 이론을 적용한 피로수명 해석을 수행하였다. 내추락 하중 조건에서 정적강도 해석의 최대응력은 가위형 링크 부위에 1,080MPa를 나타내었으며, 이는 온도감소계수를 적용한 허용응력보다 약 5%의 여유를 가지고 있다. 피로하중 조건에서 최대응력은 가위형 링크 부위에 876MPa로 가장 높았으며, 이 때 응력방정식 계수도 0.019MPa/N으로 최대를 나타내었다. 피로수명 해석에 의한 안전수명은 가위형 링크 상단부에 있는 프레팅 영역이 416,667H이고, 다른 부위는 무한수명이 산출되어, 항공기 엔진 지지구조물(가위형 링크, 직선형 링크)은 피로수명 요구도를 충족하는 것으로 확인되었다.

• Safety and Health at Work
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• 제11권4호
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• pp.543-549
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• 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.

• 한국도시철도학회논문집
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• 제6권4호
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• pp.249-257
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• 2018

교통사상사고 원인 중 선로근접 및 무단통행으로 인한 사고가 많이 발생하고 있다. 운행선 근접공사 시 열차운행에 지장을 주지 않고, 작업자의 안전확보 및 작업효율을 높이기 위해 철도선로용 안전펜스가 사용되고 있다. 하지만 철도선로에 적용되는 레일저부형 안전펜스는 열차주행 시 안전펜스의 간섭여부를 확인할 필요가 있다. 본 연구에서는 철도선로용 안전펜스의 열차운행 시 지장여부를 확인하기 위하여 국내에서 운행되고 있는 열차들과 안전펜스 설치 시 이격간격을 분석하였다. 또한, 국내 열차종류별 열차 풍압에 대한 횡방향 하중조건을 산정하여 철도선로용 안전펜스의 설치간격에 따른 수치해석을 수행하였다. 본 연구를 통하여 철도선로용 안전펜스의 적정 이격거리는 차량한계로부터 200mm 이상을 확보하고, 열차풍압을 고려한 철도선로용 안전펜스의 적정 설치간격을 산정할 필요가 있음을 확인하였다.

• 한국안전학회지
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• 제24권6호
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• pp.136-143
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• 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.

• 대한인간공학회지
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• 제29권3호
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• pp.311-320
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• 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.