• 국제학술발표논문집
• /
• The 9th International Conference on Construction Engineering and Project Management
• /
• pp.728-735
• /
• 2022

Roofers get exposed to increased risk of knee musculoskeletal disorders (MSDs) at different phases of a sloped shingle installation task. As different phases are associated with different risk levels, this study explored the application of machine learning for automated classification of seven phases in a shingle installation task using knee kinematics and roof slope information. An optical motion capture system was used to collect knee kinematics data from nine subjects who mimicked shingle installation on a slope-adjustable wooden platform. Four features were used in building a phase classification model. They were three knee joint rotation angles (i.e., flexion, abduction-adduction, and internal-external rotation) of the subjects, and the roof slope at which they operated. Three ensemble machine learning algorithms (i.e., random forests, decision trees, and k-nearest neighbors) were used for training and prediction. The simulations indicate that the k-nearest neighbor classifier provided the best performance, with an overall accuracy of 92.62%, demonstrating the considerable potential of machine learning methods in detecting shingle installation phases from workers knee joint rotation and roof slope information. This knowledge, with further investigation, may facilitate knee MSD risk identification among roofers and intervention development.

• 한국산업보건학회지
• /
• 제18권2호
• /
• pp.141-148
• /
• 2008

To prevent musculoskeletal disorders(MSD) for dental hygiene students, who will potentially be at high risk of developing MSD while performing oral prophylaxis practice, an MSD prevention education program was designed and was offered to a group of dental hygiene students to find whether the program is effective. Before the program started and three months after the program ended, changes in the students' posture were filmed to observe them. The final subjects for analysis included 30 students in the experimental group and 41 students in the control group. To verify differences between the experimental and the control groups, repeated measures ANOVA was carried out before and after the program. After the education program, the experimental group's RULA scores for neck, left upper arm, right forearm, and wrist, RULA A score on both left and right side, RULA B score on left side, and total RULA score were significantly lowered during the operation on the upper jaw, compared with that of the control group. And, during the operation on the lower jaw, the experimental group's RULA A score, RULA B score, and total RULA score were very significantly lowered. The results of this study suggest the MSD prevention education program is effective in preventing the disorder. Thus, the program can be utilized as an education program for preventing MSDs during dental hygiene students' oral prophylaxis practice and clinical practice.

• 한국안전학회지
• /
• 제31권4호
• /
• pp.111-119
• /
• 2016

This study aimed to analyze postures that were frequently conducted in manufacturing industry. To find grip strength and muscle activities of each posture, Maximum Voluntary Contraction (MVC) and ElectroMyoGraphy (EMG) were measured. Based on the results of this study, the most appropriate posture could be suggested and used as a basic information for preventing musculoskeletal disorders. Most work-related musculoskeletal disorders have been occurred in the fields of manufacturing industry. According to previous studies, it was reported that the rate of musculoskeletal diseases of upper extremity was higher than that of other body parts. Accordingly, there were many studies about discomfort and grip strength of upper extremity. However, these studies dealt with single selection of wrist, elbow and shoulder. So, it was insufficient for comprehensive studies about upper extremity. And in order to improve the work posture, the physiological changes being generated by the combination of wrist, elbow and shoulder postures should be observed and analyzed. In order to conduct this study, thirty university students who had no records of MSDs involved were recruited. Independent variables were postures of wrist(pronation, neutral, supination), postures of elbow(flexion $45^{\circ}$, $90^{\circ}$) and postures of shoulder(flexion $0^{\circ}$, $90^{\circ}$). And dependent variables were MVC values and EMG values. Jamar dynamometer and TeleMyo 2400T G2 was used to measure MVC and EMG. MVC and EMG for 12 postures were measured for three second and for three times. Experiment was performed randomly. A 10 minutes rest period was provided after each t. To measure muscle load, the EMG signals of eight muscles (Biceps, Medial triceps, Lateral triceps, Brachioradialis, Extensor carpi ulnaris, Extensor carpi radialis, Flexor carpi ulnaris and Flexor carpi radialis) were evaluated. MVC values and EMG values were analyzed using Minitab ver. 14. The results showed that MVC value was the highest at shoulder $0^{\circ}$, elbow $45^{\circ}$ and wrist supination. In case of wrist postures, MVC of supination is the highest. In case of elbow and shoulder postures, MVC of flexion $45^{\circ}$ and $0^{\circ}$ was the highest. It was found that there were interaction between wrist and elbow posture under shoulder flexion and between shoulder and wrist under elbow flexion $45^{\circ}$. In case of the angle of shoulder $0^{\circ}$, elbow $45^{\circ}$ and wrist supination, the EMG values of four muscles(Medial Triceps, Extensor carpi ulnaris, Extensor carpi radialis, Flexor carpi ulnaris) were the highest. Based on this study, it is worth to note that the combination postures of upper extremity have a large impact on the MVC and EMG. The optimal condition upper extremity was shoulder flexion $0^{\circ}$, elbow flexion $45^{\circ}$ and wrist supination for preventing work-related musculoskeletal disease.

• 대한안전경영과학회지
• /
• 제17권3호
• /
• pp.133-141
• /
• 2015

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.

• 대한안전경영과학회:학술대회논문집
• /
• 대한안전경영과학회 2011년도 춘계학술대회
• /
• pp.319-328
• /
• 2011

작업관련성 근골격계질환을 효율적으로 예방하기 위한 제일 중요한 요소는 관련위험 요인들에 대한 정확한 평가이다. 그러나 대부분의 근골격계질환 관련 위험도 평가도구들은 주관적평가의 가능성에 대한 지적을 많이 받아왔다. 본 연구에서는 이와 같은 지적에 대한 좀 더 체계적인 분석을 위하여 주요 평가도구들(OWAS, RULA, REBA)에 대한 일종의 민감도 분석을 수행하였다. 분석은 다음과 같이 크게 두 가지 관점에서 진행되었다; 1) 숙련자와 비숙련자에 의한 평가결과에 대한 비교, 2) 평가 시점에 따른 평가 결과의 일관성에 대한 비교. 본 연구의 주요 결과는 다음과 같다; 1) RULA와 REBA의 경우, 숙련자와 비숙련자 간에 평가결과의 차이는 통계적으로 유의 하였다. 반면에 OWAS의 경우에는 숙련자와 비숙련자간에 평가결과에 있어서 통계적으로 유의한 차이를 보이지 않는 것으로 나타났다, 2) 적용된 모든 평가도구들은 그 결과에 있어서 평가 시점에 따라 통계적으로 유의한 차이가 있는 것으로 나타났다. 본 연구에서는 연구 목적에 따른 1차 결과를 제시하였다. 이 결과를 토대로 하여 향 후 형식이나 내용면에 있어서 좀 더 확장된 개념의 연구의 수행을 통하여 평가도구를 사용하는데 있어서 체계적이고 실용적인 지침을 도출해 내리라고 판단된다.

• 한국안전학회지
• /
• 제23권2호
• /
• pp.30-36
• /
• 2008

This paper suggests the best work conditions, including short break time and number of mouse clicks on a computer, to prevent MSDs(Musculoskeletal Disorders) on VDT(Visual Display Terminal) work. Discomfort measures are calculated according to the Borg's CR-10 Scale. The short break time conditions are grouped into 7, 15, and 30 seconds after every 10-minute work period and the number of mouse clicks are divided into 10 clicks/min, 20clicks/min, and 30clicks/min. The result of the ANOVA on the shift value of subjective discomfort shows the following: 1) Regarding the break time and the number of mouse clicks, there are statistical differences between the measured values for the neck and the wrist(p<0.05). 2) Regarding the number of mouse clicks, there are statistical differences between the measured values for the shoulder and the forearm(p<0.1). 3) Regarding the break time and the number of mouse clicks, there are no statistical differences between the measures values for the eyes, upper arms and back(p<0.1).

• 대한인간공학회지
• /
• 제31권5호
• /
• pp.671-685
• /
• 2012

Objective: This study aims to investigate subjects in recuperation to identify the following factors with regard to work-related musculoskeletal diseases: diagnosis in the context of occupational and environmental medicine; assessment systems for judging work-relatedness; recuperation management; workplace management; prevention programs; and care after returning to work. This study intends to analyze differences between subjects and determine what characteristics of subjects account for the differences. Method: A survey was administered to 1,664 workers who were approved by the Korea Worker's Compensation & Welfare Service between 2003 and 2005 for recuperation due to work-related musculoskeletal diseases. The data of 229 subjects who responded the survey questionnaire related to recuperation were analysed. Results: According to the results, demographic, occupational, and musculoskeletal disease-related factors were significant. The demographic factors included gender, age, marital status, and region, while occupational factors included working period, work type, size of workplace, and industry type. The factors related to musculoskeletal diseases were the part of the body in pain, the tissues in pain, and the existence of dysfunction. The above factors were associated with statistically significant differences in the following areas: revealed symptom period, symptoms-diagnosis period, and application for recuperation approval periods; diagnosis and care institutes for recuperarion; the state of patients (body parts in pain, tissues in pain, and existence of dysfunction); return to work; and care after returning to work. Conclusion: The results of this study can serve as basic data in setting priorities for prevention programs for work-related musculoskeletal diseases and selecting target groups.

• 한국산업보건학회지
• /
• 제23권3호
• /
• pp.307-314
• /
• 2013

Objectives: The aim of this study was to determine the prevalence of symptoms relating to musculoskeletal disorders (MSDs) and investigate the risk factors among researchers at university laboratories. Methods: 209 researchers were included in this study, drawn from 27 laboratories at three universities in Korea. Checklists for MSD symptoms and risk factor assessment were utilized. Results: The symptoms checklist showed reliable results with Cohen's Kappa 0.33-0.56, percent agreement 81.0-96.8%, and correlation coefficient 0.41-0.63. The overall prevalence of MSD symptoms was 68.9%, while the prevalence in specific parts of body were as follows: shoulders (47.6%), lower back (46.9%), neck (46.9%), knees (25.4%), wrists (20.1%), elbows (13.6%). The symptom prevalence among women was higher than among men (OR 2.67, 95% CI 1.37-5.18). Daily exposure time was observed to be a significant risk factor for developing MSD symptoms (OR 2.14-6.07). Conclusions: This study suggested that repetitive pipetting and static work posture are the most significant risk factors for MSD symptoms among laboratory researchers.

• 대한인간공학회지
• /
• 제32권2호
• /
• pp.199-205
• /
• 2013

Objective: The aim of this study is to investigate the job rotation implementation at medium- or small-industries and to identify the viewpoint on job rotation as preventive activity of work-related musculoskeletal disorders(WMSDs). Background: Job rotation has been implemented in many industrial areas in order to prevent the WMSDs as one part of ergonomic program. Generally, the cases of implementation of ergonomic program or successful cases of job rotation were reported on the side of major or large company. Therefore, this study tried to inspect the current state of job rotation implementation at medium- or small-industries. Method: Survey was carried out for randomly contacted forty seven mangers responsible for safety. Survey contained the questionnaires on the general state of company, shift-work and job rotation. Results: The ratio of work-shift in medium- and small-industry was 34.0% and the ratio of job rotation was 19.1%. For manufacturing industry, the ratio was 37.9% and 17.2%, respectively. Conclusion: The implementation ratio of job rotation was relatively low considering the results of previous studies. Many managers appealed the quality decreasing of goods and the injuries of workers due to job rotation, though agreed to train the multi-functional worker and to prevent the WMSDs. Application: The results can be used for the fundamental data how the job rotation will be properly implemented in medium- and small-industry as an administrative control for MSDs.

• 대한안전경영과학회지
• /
• 제14권4호
• /
• pp.59-70
• /
• 2012

This study compared data regarding industrial accidents and awareness level for beauty product safety for four main parts of beauty industry such as hair-care, nail-care, skin-care, and make-up. Major risk factors in beauty industry are dust, musculoskeletal disorders, and organic solvent of beauty product in order of percentage. The specific types of industrial accidents in beauty industry are mainly associated with musculoskeletal system such as cuts, sprain, and varicose vein. They are mainly compensated by personal budget. The awareness levels of chemical and heavy metal containment for beauty product by beauty industry employee were 77.2% and 59.1% respectively. Most employee confirmed only important items of labelling requirement of beauty product. Also, most employee did not understand MSDS(Materila Safety Data) for chemicals used in beauty industry. Only 38.1% of beauty industry employee has had safety education while most employee (73.6%) realized that they needed safety education. Also, safety education supervised by KOSHA(Korea Occupational Safety and Health Agency) was the most preferred. This study would be good basis for safe and healthy working environment of beauty industry employee.