• 대한인간공학회지
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• 제28권1호
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• pp.9-19
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• 2009

Repetitive movement, inadequate working posture, overuse of force, physical contact with sharp edge, vibration and temperature were well known risk factors of WMSDs (Work-related Musculoskeletal Disorders). Many researchers have investigated the relationship between inadequate working postures and incidences of WMSDs of the upper extremities, whereas relatively few researchers have tried to evaluate workload associated with the lower-body postures. The effects of lower-limb postures including various knee flexion angles on the subjective discomfort, heart rate and EMG of lower-limb muscles were investigated in this study. Thirty graduate students were asked to maintain thirteen different body postures, and heart rate and EMG data of five muscle groups (electro spine, biceps femoris, vastus medialis, gastrocnemius and tibialis anterior) from each posture were collected during fifteen minutes sustaining tasks. All participants were also asked to report their discomfort ratings of body parts. Results showed that high subjective discomfort ratings and heart rates were reported at the postures of knee angles of $60^{\circ}$ and $90^{\circ}$, whereas low discomfort ratings were founded at the postures of chair heights with 20cm, 40cm, and sitting with crossed legged. The change of median frequency for each muscle group during fifteen minutes tasks was investigated for each body posture to evaluate the relationship between muscle fatigue and body posture. It was found that the trends of changes of median frequency were different based on muscle group as well as lower-limb body posture from this study.

• 대한인간공학회지
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• 제26권2호
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• pp.35-44
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• 2007

Work-related musculoskeletal disorders (WMSDs) are a major problem in industries in which manual materials handling is performed by workers. To prevent these WMSDs, it is necessary to understand the muscular strength capability and use this knowledge to design job and selection and assignment of workers. Even though two-hands lifting activity of manual materials handling tasks are prevalent at the industrial site, many manual materials handling tasks which require the worker to perform one-hand lifting are also very common at the industrial site and forestry and farming. However, a few researches have been done for one-hand lifting activity of manual materials handling tasks. The objective of this study is to compare one-hand and two-hands lifting strength in terms of static and dynamic strength of the lifting activity for the ranging from the height of knuckle to elbow. It is shown in this study that the isometric lifting strength of one-hand is ranging from 54.7 to 63.3% of the one of two-hands. However, it is found that there is no significant difference between a person's isometric lifting strength for left-hand and right-hand. It is also shown that there is no significant difference between the peak force under the dynamic sub-maximal loading with one-hand and two-hands lifting activity. Similar results were obtained for the peak acceleration and peak velocity under the dynamic sub-maximal loading with one-hand and two-hands lifting activity. Isometric lifting strength at the height of knuckle was ranging from 2 to 3 times of the dynamic peak force during sub-maximal lifting. It is concluded that the dynamic peak forces under the sub-maximal loading are not highly correlated with the isometric lifting strength in similar postures.

• 대한인간공학회지
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• 제32권4호
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• pp.321-331
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• 2013

Objective: The aim of this study is to review the literatures on the regulation, standard and guideline for the human vibration in Korea and other countries. Background: This review can be used to prevent various diseases caused by the human vibration as a basis for the development of the policy. Results: In Korea, the general employers' duties related to human vibration are set forth the Health Measures(Article 24) in the Occupational Safety and Health Act. And then an employer shall take measures to protect the health of the workers concerned by improving other working conditions relating to working hours for the vibration prevention measures referred to in Article 24 of the Act. The European Union adopted a Directive in 2002 on minimum requirements for the health and safety of workers exposed to vibration. New Regulations on Vibration at Work will be introduced in Great Britain on 2005 to implement the Directive. In the U.S., both ANSI and ACGIH adopted the ISO standard for measurement and suggested exposure action and limit values. In Japan, the Ministry of Labor decided that the vibration syndrome among operators of rock drills and riveters etc. could be included in an occupational disease(1947). In addition, ISO standard was based on proposals and draft documents of many countries such as U.K, Japan and European, etc. Conclusion: In Korea, Occupational Safety and Health Act prevent vibration to health, but do not include exposure limits. It is therefore important to consider the new duties regarding to vibration risks added to the general duties.

• 한국심리학회지 : 문화 및 사회문제
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• 제9권spc호
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• pp.107-122
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• 2003

본 논문에서는 근골격계질환, 특히 직업성요통에 관련되는 위험요인의 영향을 종합적으로 살펴보고자 하였다. 첫째로 물리적인 요인의 영향을 알아보기 위하여 해석적인 인체역학 모델과 NIOSH(National Institute for Occupational Safety & Health) Guidelines를 이용하여 자동차 조립작업의 직업성 요통관련 위험도를 평가하였다. 총 246 작업자에 대한 분석을 수행하였는데, 분석결과 총 20개의 작업에서 L5/S1에서의 압축력이 300kg이 넘었으며 44개의 작업은 NIOSH Guidelines에 의한 분석결과, 최저허용기준치(ACTION LIMIT)을 넘는 것으로 나타났다. 둘째로 사회심리적 요인과 직업성요통의 관계에 대해 분석하였다. 사회심리적 요인의 영향을 알아보기 위하여 증상과 PWI(Psychosocial Well-being Index)를 토대로 한 설문을 이용하여 246명 작업자 모두에게 설문조사를 실시하였다. 그 결과 207명의 작업자가 직업성 요통증상을 경험한 적이 있으며 특히 27명의 작업자는 유병자로 분류된 바 있는 사람들이었다. PWI 점수를 근거로 하여 나눈 두 집단(저스트레스군, 고 스트레스군)은 증상이나 진단결과에 있어서 통계적으로 유의한 차이를 보이지 않았다. 또한 사회심리적 스트레스와 작업강도와의 관계를 살펴보면 주로 작업자세요인과 사회심리적 스트레스가 유의한 관계를 가지는 것으로 나타났다. 마지막으로 직업성요통의 발생에 대하여 경로분석을 수행하였다. 분석결과 인구학적 요인, 사회심리적 요인, 작업특성 요인이 직업성 요통에 직접적으로 영향을 미쳤으며, 개인특성요인 즉, 작업경험, 흡연, 수면시간 등은 직업성요통에 직접적인 영향을 미치는 않은 것으로 나타났다. 그러나 개인특성요인은 직업성 요통에 유의한 영향을 미치는 사회심리적 요인과는 밀접한 관계를 가졌다. 향후 다양한 직종에서의 이와같은 경험적 연구결과가 축적되어 우리나라의 조직문화적 특성을 고려한 직업성 요통에 대한 위험모델에 구축되어야 한다고 사료된다.

• 한국산업보건학회지
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• 제15권2호
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• pp.104-113
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• 2005

A variety of ergonomic assessment methods of lifting tasks known as a major cause of work-related lower back pain have been used. But there is a limited information in choosing the most appropriate assessment method for a particular job and in finding out strengths and weakness of the methods. The purpose of this study was to assess and compare the ergonomic risks of lifting tasks in a marine diesel engine production industry by three lifting ergonomic assessment tools widely used: the National Institute for Occupational Safety and Health(NIOSH) Revised Lifting Equation(NLE), the Washington Administrative Code 296-62-0517(WAC), and the Snook Tables. Lifting index(weight of load/Recommended Weight Limit) of NLE($LI_{NLE}$) was above 1 at 34 tasks(75.6%) of a total number of 45 lifting tasks. LI of WAC($LI_{WAC}$) was above 1 at 11 tasks(24.4 %). LI of Snook Table($LI_{Snook}$) was above 1 at 29 tasks(64.4%). Thus, LI was high in orders of $LI_{NLE}$ > $LI_{Snook}$ > $LI_{WAC}$. There were significantly high correlations among three Lls(p<0.01). The correlation coefficients between $LI_{NLE}$and the other three Lls($LI_{WAC}$ and $LI_{Snook}$) were r=0.93 and r=0.88, respectively. The linear regression equations were y = 0.444x + 0.11(r=0.93) between $LI_{NLE}$ and $LI_{WAC}$, y = 0.93x + 0.008(r=0.88) between LI(NLE) and $LI_{Snook}$. The LI values by WAC was significantly lower than those by the other tools. The compared features, strength and limitation among these tools were described in this paper.

• 대한인간공학회지
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• 제36권3호
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• pp.183-196
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• 2017

Objective: The purpose of this research was to assess the agreement between job physical risk factor analysis by ergonomists using ergonomic methods and physical examinations made by occupational physicians on the presence of musculoskeletal disorders of the upper extremities. Background: Ergonomics is the systematic application of principles concerned with the design of devices and working conditions for enhancing human capabilities and optimizing working and living conditions. Proper ergonomic design is necessary to prevent injuries and physical and emotional stress. The major types of ergonomic injuries and incidents are cumulative trauma disorders (CTDs), acute strains, sprains, and system failures. Minimization of use of excessive force and awkward postures can help to prevent such injuries Method: Initial data were collected as part of a larger study by the University of Utah Ergonomics and Safety program field data collection teams and medical data collection teams from the Rocky Mountain Center for Occupational and Environmental Health (RMCOEH). Subjects included 173 male and female workers, 83 at Beehive Clothing (a clothing plant), 74 at Autoliv (a plant making air bags for vehicles), and 16 at Deseret Meat (a meat-processing plant). Posture and effort levels were analyzed using a software program developed at the University of Utah (Utah Ergonomic Analysis Tool). The Ergonomic Epicondylitis Model (EEM) was developed to assess the risk of epicondylitis from observable job physical factors. The model considers five job risk factors: (1) intensity of exertion, (2) forearm rotation, (3) wrist posture, (4) elbow compression, and (5) speed of work. Qualitative ratings of these physical factors were determined during video analysis. Personal variables were also investigated to study their relationship with epicondylitis. Logistic regression models were used to determine the association between risk factors and symptoms of epicondyle pain. Results: Results of this study indicate that gender, smoking status, and BMI do have an effect on the risk of epicondylitis but there is not a statistically significant relationship between EEM and epicondylitis. Conclusion: This research studied the relationship between an Ergonomic Epicondylitis Model (EEM) and the occurrence of epicondylitis. The model was not predictive for epicondylitis. However, it is clear that epicondylitis was associated with some individual risk factors such as smoking status, gender, and BMI. Based on the results, future research may discover risk factors that seem to increase the risk of epicondylitis. Application: Although this research used a combination of questionnaire, ergonomic job analysis, and medical job analysis to specifically verify risk factors related to epicondylitis, there are limitations. This research did not have a very large sample size because only 173 subjects were available for this study. Also, it was conducted in only 3 facilities, a plant making air bags for vehicles, a meat-processing plant, and a clothing plant in Utah. If working conditions in other kinds of facilities are considered, results may improve. Therefore, future research should perform analysis with additional subjects in different kinds of facilities. Repetition and duration of a task were not considered as risk factors in this research. These two factors could be associated with epicondylitis so it could be important to include these factors in future research. Psychosocial data and workplace conditions (e.g., low temperature) were also noted during data collection, and could be used to further study the prevalence of epicondylitis. Univariate analysis methods could be used for each variable of EEM. This research was performed using multivariate analysis. Therefore, it was difficult to recognize the different effect of each variable. Basically, the difference between univariate and multivariate analysis is that univariate analysis deals with one predictor variable at a time, whereas multivariate analysis deals with multiple predictor variables combined in a predetermined manner. The univariate analysis could show how each variable is associated with epicondyle pain. This may allow more appropriate weighting factors to be determined and therefore improve the performance of the EEM.