• 대한인간공학회지
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• 제34권2호
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• pp.135-143
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• 2015

Objective: The purposes of this study are to investigate ergonomic problems and to propose their improving measures in office environment of big general hospitals. Background: Office tasks have varying risk factors of work-related musculoskeletal disorders (WMSDs). The first symptom resulted from the office work was recognized as an occupational disease in Korea in 1986. Although the symptoms have increased since its first recognition, there has been few study on the effect of office work environment settings. Method: First, the author took pictures of working scenes performed in three big university hospitals. Next, the pictures were analyzed in view point of ergonomics. Based on the analysis, their improving measures were proposed for reducing work stress. Results: The results showed that most physical office environment settings such as dimensions of tables/desks and chairs, leg room, thigh, knee and foot clearances, and chairs used did not satisfy the ergonomically recommended design guidelines. In addition, some clerks placed personal belongings under their desks, put monitors in high position and did not lean against the backrest of chairs in seated tasks, which resulted in poor working postures of leg, back, neck etc. It is recommended that the hospital management should provide their clerks with ergonomically designed office furniture and continuously perform ergonomics training program for raising clerks' recognition for office ergonomics. Conclusion: Most office environment settings investigated in this study were not in good condition in view point of ergonomic design for the settings. Application: It would be useful as basic data for establishing ergonomically good office environment in hospitals.

• 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.

• 한국안전학회지
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• 제26권1호
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• pp.49-57
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• 2011

A questionnaire study was carried out to understand the status of performing the risk assessment of work-related musculoskeletal disorders(WMDSs), which is the employers' legal responsibility when the employees are involved in doing tasks with risk factors. Employers or managers from 340 companies and the representative employees from 250 companies participated in the survey. According to the participated employers and employees, 35.0~46.2% of companies had performed the first risk assessment before the end of 2005. However, it is presumed that the real condition might not be as much as the result, because most companies were very reluctant to took part in the survey. It was found that the type of business and size of the company are the main factors affecting the performance of the risk assessment in terms of the performing ratio, method, and so on. The participants were positive in the thought that the assessment would be helpful in preventing msuculoskeletal disorders, while there was a little difference between the employers and employees in the thought that the assessment would be helpful in finding the injuries in the early stage. It was found that it is necessary to modify and improve the definition and criteria of the tasks to be examined in the assessment.

• 한국안전학회지
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• 제23권5호
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• pp.119-124
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• 2008

Many automobile assembly workers often do several cycles of tasks continuously, i.e., without breaks, to get a longer break. This is not recommended since the dose of fatigue increases exponetially with time and it takes much longer time to recover. In this study, a laboratory experiment was conducted to investigate the effect of work/rest schedules on workload of a repetitive upper-limb task. Eleven male subjects participated in the experiment, in which simulated screw driving tasks were carried out repetitively with 3 different work/rest schedules: standard breaks(1 cycle of work at a time, 60 20-s breaks), medium breaks(5 cycles of work at a time, 12 100-s breaks), and long breaks(10 cycles of work at a time, 6 200-s breaks). The result showed that medium- and long-breaks schedules significantly increased the level of perceived discomfort and %HRR as compared to the standard-break schedule. The subjects' preference was not statistically different among work/rest schedules, which might be caused from the absolutely low level of workload of the experimental tasks. From the results, it is recommended to have frequent and shorter breaks rather than infrequent and longer breaks to decrease the level of physical workload. A more expanded studies, however, should be carried out to provide more practical safety guidelines on the work practice of continuous working without breaks among automobile assembly workers.

• 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.

• 한국산업보건학회지
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• 제16권2호
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• pp.183-192
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• 2006

Predicting energy expenditure (EE) is important to prevent work-related musculoskeletal disorders (WMSDs). The problem to predict EE is that the standard of EE is based on western data. The authors checked average EE by job categories to provide basic data for suggesting proper work intensity for Korean workers. This study was conducted from 2003 to 2005. Study subjects were recruited from 4 car parts assembly plant, 2 car assembly plant, 2 Heavy machine manufacturing plant and 2 shipyards. Total study subjects were 515 male workers. To estimate VO2max, sub-maximal test was conducted to measure VO275%max by bicycle ergometer (Combi Co, Aerobike 75XL II). Heartbeats were recorded with heartbeat recorder (Polar Electro Co, Finland, S810) during work. EE of work was calculated by recorded heartbeat and individual regression equation which was derived from sub-maximal test. Subjects were classified into 4 industry and 8 work posture, 23 job task categories. Mean EEs (S.D.) according to industry classification (kcal/min) were 4.9 (0.7), 4.8 (0.7), 4.9 (0.7), 5.0 (0.9), and 4.0 (0.5) for Car Part manufacture, Car Assembly, Ship Building, Heavy Machinery Manufacture, and Hospital Office, respectively. The results suggest that Korean male workers of exceeding to the NIOSH criteria will be needed to plan for job rescheduling to maintain $worker^{\circ}$Øs health. Further study to establish Korean work intensity standard would be needed.

• Journal of Preventive Medicine and Public Health
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• 제32권1호
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• pp.48-59
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• 1999

본 연구는 Rapid Upper Limb Assessment(RULA)를 이용하여 자동차 조립작 업에 대한 인간공학적 작업평가를 하고, 이 결과와 작업관련 상지 근골격계 질환의 자각증상율 및 작업특성 변수들의 연관성을 분석함으로써, RULA결과가 관련 신체부위의 통증이나 불편함으로 보고되는 근골격계 부하의 좋은 지표가 될 수 있는지, RULA평가체계를 이용하여 작업 위험도가 적합한지 여부를 평가할 수 있는가를 보고자 하였다. 자동차 제조업 작업자 314명을 대상으로 근골격계질환 자각증상설문과 RULA를 이용한 작업평가를 하였으며, 다음과 같은 결과를 얻었다. 1. NIOSH의 작업관련 근골격계 질환의 감시기준(surveillence criteria)에 따라 자각증상을 조사한 결과, 연구대상자 중 목 32.8%, 어깨 26.4%, 팔 10.5%, 손 29.3%, 허리 41.4%였으며, 한가지 이상 의 증상을 보이는 경우는 62.4%의 분포를 보였다. 2. 품질관리부에 비해 조립부서 작업자 틀이 전체 증상과 어깨, 허리, 팔 및 손부 위 증상에서 더 높은 유증상률을 보였다(p<0.05). 3. 부서별 RULA를 이용한 작업평가 결과, 서브/조립반과 의장반의 공정이 높은 위험점수를 보였다. 전체 조립부서에 대한 평가결과 적합한 작업은 3.02%였고, 62.8%가 부적합한 작업으로 작업전환이나 중재조치가 필요한 경우였다. 자각증상과 RULA를 이용한 작업평가 결과를 비교한 결과 RULA점수가 클수록 자각증상율이 높음을 보였다.(p<0.05) 4. RULA평가지표와 자각증상사이의 관련성을 보기 위하여, RULA지표와 기타 작업관련요인들을 독립변수로, 자각증상유무를 종속변수로 하여 다중 로지스틱 회귀분석을 실시하였다. 최종적으로 증상유무를 가장 잘 설명하는 회귀모형에 대한 분석결과는 다음과 같다. 모든 증상군에 대해서는 반복작업(OR 2.183), 진동공구 사용(OR 2.775)과 총 위험도 점수(OR 2.250); 목 부위 증상군에서는 상완의 자세점수(OR 1.786), 상완 및 손부 위의 총점수(OR 1.634) ; 어깨 증상군은 상지의 근사용(OR 3.076), 상완 및 손부 위의 총점수(OR 1.798); 어깨와 목 부위를 합한 증상군은 상완 및 손부위의 총점 수(OR 1.715)와 상지의 근사용 점수(OR 2.057); 팔 증상군에서는 상지의 근사용 점수(OR 10.662) ; 손 부위 증상군에 대해서는 손목의 자세/손목 비틀림 지표 (OR 2.068)와 상지의 근사용 점수(OR 2.215); 허리부위 증상군에서는 하지의 근사용 점수(OR 2.601)가 통계적으로 유의한 지표였다.(p<0.05) 이상의 결과에서 작업관련 상지근골격계 자각증상과 RULA 점수사이에는 연관성이 있음이 관찰되었다. 이는 RULA가 직업성 질환을 유발할 수 있는 근골격계 부하에 폭로된 작업자들을 평가하는, 일차적인 작업 위험도 평가도구(Screening tool)로서 쓰일 수 있음을 말해준다. 다만 향후 RULA 사용에 있어서 상지(upper limb)와 허리부위(back)의 평가를 구분하고, 기타 다른 작업관련 요인들에 대한 평가체계를 보완하는 것이 필요하다.

• 한국시뮬레이션학회논문지
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• 제15권3호
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• pp.93-101
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• 2006

근래에 작업자의 근골격계 질환이 산업현장의 주요한 논제로 등장하였다. 이러한 문제를 줄이기 위하여 다양한 방법들이 사용되고 있는데 그 중의 하나가 제품설계, 치구설계, 작업장 설계를 할 때 작업자의 안전을 최대한 확보하도록 설계단계에서 개선을 하는 것이다. 최근에 급속히 발전하고 있는 3D 시뮬레이션 기술을 사용하면 작업장을 설계하는 단계에서 제품 및 치구의 3D 도면을 이용하여 가상의 작업공간을 구축한 후 작업자의 작업 자세를 사전에 검증해 볼 수 있기 때문에 작업장 구축 후 발생할 수 있는 많은 문제점들을 사전에 검증하여 설계실패비용을 최소화할 수 있다. 본 논문은 3D 작업자 시뮬레이션을 이용하여 굴삭기 공장의 특정한 공정을 대상으로 개선 및 최적화를 하기위한 연구다. 먼저 CATIA를 이용하여 제품과 치구 등 작업장 구축을 위한 3D 모델을 개발하였다. 그리고 IGRIP, DPM. Human 등의 개발도구를 복합적으로 이용하여 작업장에서의 작업내용을 시뮬레이션 할 수 있는 모델을 개발한 후 작업 자세에 대한 분석을 수행하였다. 분석결과는 작업장을 개선하는데 이용하였다.