Postural stability can reduce the likelihood of critical slip and fall accidents in workplaces. The present study aimed to analyze the effect of shoes type on the ability of postural control during quiet standing. The effect of workload on the body balance was also of primary concern. Thirteen healthy male undergraduate students participated voluntarily in the experimental study. Standing on a force plate with wearing slippers, sports shoes, or safety shoes, two-axis coordinate on subjects’ center of pressures (COP) was obtained in the two levels, rest and workload. For the workload level, subjects performed treadmill exercise to reach the predetermined level of physical workload. By converting the position coordinates of COPs, the postural sway length in both anterior-posterior (AP) axis and medio-lateral (ML) axis was assessed. ANOVA results showed that, in AP direction, wearing slippers significantly increased the postural sway length compared to wearing sports shoes or safety shoes. No significant difference in the mean sway length in AP axis was observed between sports shoes and safety shoes. In ML direction, both the workload and the shoes type did not significantly affect the mean length of postural sway. However, the postural sway length increased marginally with the slippers especially during the workload condition. This study explains wearing slippers may interfere with the ability of postural control during quiet standing. Physical workload decreases the ability of postural stability further.

This study tried to identify the problems associated with the posture to be analyzed and tried to suggest guidelines for MSDs(Musculoskeletal Disorders) evaluation based on working posture. A total of 50 jobs from 3 different types of industries(electronics, hospitals, automobiles) were used for MSDs evaluation study which was done by 6 observers. Two indexes were applied to identify the problem in this study which were percentage of agreement and counter-time-error rate. Specifically, ‘counter-time-error rate’ represented a degree of consistency in terms of selecting the posture to be analyzed time after time. Main results of the study were as follows; 1) The average percentage of agreement for representative posture for whole body was relatively higher than that for representative postures for individual body parts, 2) The counter-time-error rate(%) has been reduced as the evaluation process has repeated for the same job. 3) The counter-time-error rate(%) for electronics, hospitals, and automobiles were 63.4%, 61.2%, and 67.3% respectively. 4) The counter-time-error rate(%) for the job with the work cycle of 0.5 to 2 minutes were lower than that of the jobs with the work cycles less than 0.5 minute or greater than 2 minute. 5) The work cycles and the number of trials had significant effects on counter-time-error rate while the types of industries did not have significant effects on counter-time-error rate. Some guidelines could be prepared from the results of the study. Probably, there should have an extension in terms of form and matter for this study in order to have more practical output.

This study tried to develop a basis for quantitative index of working postures associated with WMSDs (Work-related Musculoskeletal Disorders) that could overcome realistic restriction during application of typical checklists for WMSDs evaluation. The baseline data(for a total of 603 jbs) for this study was obtained from automobile manufacturing company. Specifically, data for back posture was analyzed in this study to have a better and more objective method in terms of job relevance than typical methods such as OWAS, RULA, and REBA. Major statistical tools were clustering, logistic regression and so on. The main results in this study could be summarized as follows; 1) The relationship between working posture and WMSDs symptom at back was statistically significant based on the results from logistic regression, 2) Based on clustering analysis, three levels for WMSDs risk at back were produced for flexion as follows: low risk(< 18.5°), medium risk(18.5°～ 36.0°), high risk(> 36.0°), 3) The sensitivities on risk levels of back flexion was 93.8% while the specificities on risk levels of back flexion was 99.1%. The results showed that the data associated with back postures in this study could provide a good basis for job evaluation of WMSDs at back. Specifically, this evaluation methodology was different from the methods usually used at WMSDs study since it tried to be based on direct job relevance from real working situation. Further evaluation for other body parts as well as back would provide more stability and reliability in WMSDs evaluation study.

The purpose of this paper is to suggest the strategical lifting postures able to alleviate imbalanced EMG amplitude leading to an increase in low back muscle fatigue while lifting asymmetric load dynamically. Eleven male subjects are required to lift symm

This study was performed to design and develop an ergonomic equipment for strawberry sorting and packing in agricultural working environments. Potential risk of work related musculo-skeletal disorders associated with farm workers performing strawberry sor

This study tried to focus on nontraditional job that has not been studied in terms of the subjects associated with MSDs(Musculoskeletal Disorders). Specifically, dental procedure was the job to be analyzed in this study. An alternative method as well as a traditional method for viewing teeth while performing simulated dental procedures. Four graduated students did both methods(direct view and indirect view) as the subjects in this study. The method based on indirect view used a video camera and monitor to view the teeth. The experiment was conducted five times for each subject. The major findings in this study were as follows; 1) Job speed was increased with the repetitions for both methods, 2) Difference of Neck flexion between direct and indirect methods was statistically siginificant(Neck flexion for indirect method was dramatically decreased), 3) Difference of job speed between direct and indirect methods was statistically significant(Job speed for direct method was faster than that of indirect method), 4) Difference of error rate between direct and indirect methods was statistically significant(error rate for direct method was lower than that of indirect method), 5) Even though indirect method did not provide better performance in terms of job speed and error rate yet, it seemed to need a trade-off between two methods in the future since indirect method provided better working postures than that of direct method.

The psychosocial stress and musculoskeletal disorders(MSDs) have been one of major health problems for hospital workers. This study tried to understand the relationship between symptoms associated with MSDs and risk factors such as working posture, job stress, psychosocial stress and fatigue. A total number of 655 hospital workers participated in this study. Specifically, REBA was applied for evaluating working posture and a checklist prepared by KOSHA(Korean Occupational Safety and Health Agency) was used for symptom survey. A questionnaire from KOSHA was also used for collecting data associated with job stress, psychosocial stress and fatigue. All these data were formulated and modeled by path analysis which was one of major statistical tools in this study. Specifically, path analysis for the data we collected came up with several major findings. As a result, as for body part(neck), (waist) and (arms) the degree of risk of work posture measured with the use of job stress(KOSS), psycho-social stress(PWI-SF) and REBA is significantly more affected by fatigue than muscular skeletal disease related consciousness symptom. However, regarding bod(wrist), the degree of risk of work posture measured with the use of job stress(KOSS) and REBA is directly affected by muscular skeletal disease related consciousness symptom. This study is meaningful in that the study clarified the causal relations of the degree of risk of work posture, degree of fatigue, and muscular skeletal disease related consciousness symptoms by each body part measured with the use of work stress(KOSS), psycho-social stress(PWI-SF) and REBA.

Work-related musculoskeletal disorder has been associated with long hours of computer work and prolonged periods of static posture. In clinical settings, postural correction is a common treatment approach for individuals with neck, shoulder, and back pain. This study was designed to identify the effect of Forward Head Posture Correctional Device during computer work. Twelve healthy adults (mean age, 27.4 yrs; mean height, 165.0cm mean weight, 65.8 kg) participated in the study. They had no medical history of neurological or surgical problems with their upper extremity. The subjects were asked to perform Head Forward Posture under the guidance of physical therapists and the measured angles were analyzed using a 3-D motion analysis system. Markers were placed on the C7 spinous process, tragus of the ear and forward head angle was between the line from the tragus to the C7 line and the Y-axis at the C7. The statistical significance of difference between, "without" and "with" correctional device was tested by paired t-test. A level of significance was set at α=.05. In comparison of the computer work between "without" and "with" correctional device, Forward Head Angle was showed significant difference (p<.05). In conclusion, the range of Forward Head Angle was significantly decreased during computer work with the correctional device. Further research is needed to understand the nature of motor control problems in deep muscles in patients with neck, shoulder, and back pain.

목적 : 본 연구는 컴퓨터 사용시 발생하는 통증 유무 및 그 부위에 대해 알아보고, 컴퓨터 작업 자세 및 환경과 통증의 관계를 확인하고자 하였다.연구방법 : 연구대상자는 모대학교에 재학 중인 대학생 600명을 대상으로 설문 조사를 실시하였다. 설문지의 내용은 대상자의 일반적인 사항, 컴퓨터 사용 실태에 관한 항목(종류: 데스크 탑, 노트북, 이용 목적, 이용 장소, 이용 시간, 휴식 시간, 통증 정도, 통증 부위 등), 컴퓨터 작업대에 관한 항목(책상, 의자, 모니터, 키보드, 마우스)을 포함한 총 36문항으로 구성되어 있다. 컴퓨터 작업대에 관한 항목은 Ergonomics Working Group에서 개발한 Creating the ideal computer workstation: A step by step guide의 작업대 평가 부분을 번역, 수정한 것으로 컴퓨터 작업대에 관한 점수가 높을수록 통증을 유발시키는 위험이 높아진다는 것을 의미한다. 수거된 설문지는 총 414부였고, 결과분석은 불성실하게 응답한 설문지를 제외한 총 321부의 설문지 결과를 SPSS를 사용하여 빈도분석, 상관관계분석, independent t-test를 실시하였다.결과 : 컴퓨터 사용과 관련하여 통증을 느끼는 학생이 전체의 80.4%였고, 어깨/목(38.4%), 허리(28.5%), 손/손목(25.9%) 부위의 통증을 호소하였다. 통증과 유의한 상관관계를 보인 컴퓨터 작업대에 관한 항목은 모니터, 의자, 키보드였고, 통증유무에 대한 컴퓨터 작업자세 및 환경평가점수를 비교한 결과 통증이 있는 경우 컴퓨터 작업대에 관한 점수가 유의하게 높았다(p<.05).결론 : 본 연구를 통하여 컴퓨터 작업대 환경이 좋지 않을수록 근골격계 통증에 영향을 미치는 것을 알 수 있다. 컴퓨터를 빈번하게 다루는 학생 또는 사무직 근로자들에게 근골격계 예방을 위한 적절한 자세에 대한 교육 및 컴퓨터 사용 환경에 대한 인간공학적인 평가가 필요하다고 사료된다.

Observational methods to evaluate postural load have an intrinsic week point that is the problem of reliability in observing postures subjectively, although they have been widely used in assessing risk factors of work-related musculoskeletal disorders in the industry. In this study, observational reliability was discussed based on reviewing several previous studies. Practical guidelines was presented to reduce the observational errors when using video recording for the assessment of risk factors. In addition, previous studies on observational reliability were summarized and analyzed according to body parts to be observed, media for observation, objective measures, analysis, statistics, etc. It is expected that this basic study can be used to increase the applicability and accuracy of the observational methods.

본 연구는 컴퓨터 작업시 머리자세가 상부 승모근의 근전도 활성도에 미치는 영향에 대해 알아보기 위해 실시하였다. 대상자는 상지에 근골계질환이 없는 대학생 5명을 대상으로 하였으며, 표면근전도(MP100WS)를 이용하여 근 활성도를 측정하였다. 실험은 10분 동안 머리를 중립자세로 모니터를 보고 컴퓨터 작업을 수행하는 것과 문서걸이(copy holder)를 보기 위해 머리를 회전하고 컴퓨터 작업을 하는 두 가지 조건을 를 이용하여 비교 분석하였다. 머리를

최근 산업안전/보건분야에서 누적외상성질환(Cumulative Trauma Disorders： CTDs)과 직업성요통(Low Back Injury)과 같은 근골격계질환은 산업현장에서 어렵지 않게 발견할 수 있는 신종 산업재해의 일종이다. 특히 미국의 경우, 발생건수와 그로 인한 인적/물적 손실이 급격하게 증가되고 있는 것으로 나타나고 있다. 그러나 미국과 같이 근골격계질환의 폐해를 일찌감치 인식하고 그 해결방안을 연구해온 나라들에서는 현재 환자관리 및 인간공학적인 기준 등을 포함하는 예방지침들이 잘 정착되어 있는 실정이다. 우리나라의 경우에는 작업환경 등의 조건과 상황이 미국과 같은 구미 선전국과 비숫하고, 특히 제조업의 생산체계가 그런 나라들과 매우 유사하여 근골격계질환의 발생과 그로 인한 인적/물적 손실이 적지 않을 것이라고 예상할 수 있지만 아직까지 CTDs에 대한 전반적인 이해가 부족하고, 정확한 실태가 파악되지 못하였으며, 따라서 체계적인 관리 대책 또한 마련되어있지 않은 실정이다. 본 조사에서는 서울 근교의 수송기계관련 사업장의 작업들에 대한 작업자세에 중심을 둔 인간공학평가를 통하여 조사 작업의 근골격계질환에 대한 상대적인 위험도, 위험요인 등을 파악하고, 그에 따른 개선 대책의 방향을 제시하고자 하였다. 특히, 각 부위별 위험점수와 부위별 증상호소율의 상환분석결과, 작업자 개인적 수준에서는 통계적으로 유의한 차는 없는 것으로 분석되었으나, 부서별로 분석한 결과, 작업시 주로 사용하는 오른쪽 상지의 경우, 오른쪽 어깨, 팔꿈치, 손목 순으로 통계적으로 유의하게 관련이 있는 것으로 나타났다. 즉 증상호소율과 해당 신체부위의 위험도 점수는 서로 정적(positive)한 관계에 있는 것으로 나타났고, 상지 중 주로 사용하는 오른쪽 부담의 위험도 자세 점수와 증상호소는 비교적 높은 상관관계에 있는 것으로 나타났다. 따라서 이와 같은 인간공학적 분석결과는 향후 인간공학적인 개선대책의 개발 뿐만 아니라 의학쪽에서 근골격계질환을 접근하는 초기단계에서 매우 유용한 역할을 할 수 있으리라 생각된다.

본 연구는 저상작물의 농작업에서 농작업자들이 많이 취하고 있는 다양한 작업 자세들 중에서 근골격계 질환의 위험요인이라고 할 수 있는 작업 자세들이 작업부하에 미치는 영향을 생체역학적으로 분석하는데 그 목적이 있다. 본 연구에 동원된 피험자는 최근 1년 이내에 신체에 아무런 부상이 없는 건강한 성인 남자 10명 이었다. 농작업 현장에 나타나고 있는 불균형 자세를 대상으로 근전도 분석, 3D 영상분석 및 지면 반력 측정을 통하여 작업 부하를 분석한 결과는 다음과 같다. 본 연구에서 상대적분근전도를 분석결과, 작업 자세는 두장근, 승모근, 척추기립근, 대퇴직근의 적분 근전도의 크기에 통계적인 차이를 나타내지 않았다(p>0.05). 그러나 엎드려 자세에서 두장근, 승모근, 척추기립근의 근활성도가, 쪼그려 자세와 엎드려 자세에서는 대퇴직근의 근활성도가 높게 나타났다. 따라서 자세에 따른 관련 근육의 활성화 정도가 다르기 때문에 작업 자세에 따라서 관련 근육의 부담을 고려하여 작업 자세를 수시로 바꾸어야 한다고 사료된다. 또한 작업 시간이 경과함에 따른 상대 적분근전도는 쪼그려 자세와 엎드려 자세에서 증가하는 경향을 나타냈다. 평균주파수는 각 근육별 자세에 따라서 나타나는 반응이 약간 다르게 나타났으며, 특히 쪼그려 자세의 경우 본 연구의 모든 근육에서 평균주파수가 감소하는 경향을 나타내어서 장시간 작업을 할 때 인체 모든 부위에 작업 부담을 주는 가장 불균형한 작업 자세라고 할 수 있다. 각 관절모멘트 분석결과, 발목관절에서는 엎드려 자세, 무릎관절에서는 선 자세, 고관절에서는 엎드려 자세의 최대모멘트가 각각 가장 크게 나타났다. 따라서 자세에 따라서 각 관절별로 작업 부하가 다르기 때문에 근골격계의 질환을 예방하기 위해서는 작업장 환경을 개선해야 한다고 판단된다.

A mobile manipulator is a system with a robotic manipulator mounted on top of a mobile base. It has both indoor and outdoor applications for transporting or transferring materials. When a user gives commands, they are usually at high levels such as “move the object to the table,” or “tidy the room.” By intelligently decomposing these complex commands into several subtasks, the mobile manipulator can perform the tasks with a greater efficiency. One of the crucial subtasks for these commands is the pick‐and‐place task. For the mobile manipulator, selection of a good base position and orientation is essential to accomplishing this task. This paper presents an algorithm that determines one of the position and orientation of a mobile manipulator in order to complete the pickand‐ place task without human intervention. Its effectiveness are shown for a mobile manipulator with 9 degrees‐of‐freedom in simulations