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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Ergonomics Society of Korea
Journal Basic Information
Journal DOI :
The Ergonomics Society of Korea
Editor in Chief :
Volume & Issues
Volume 30, Issue 6 - Dec 2011
Volume 30, Issue 5 - Oct 2011
Volume 30, Issue 4 - Aug 2011
Volume 30, Issue 3 - Jun 2011
Volume 30, Issue 2 - Apr 2011
Volume 30, Issue 1 - Feb 2011
Selecting the target year
Reproducibility of Electromyography Signal Amplitude during Repetitive Dynamic Contraction
Mo, Seung-Min ; Kwag, Jong-Seon ; Jung, Myung-Chul ;
Journal of the Ergonomics Society of Korea, volume 30, issue 6, 2011, Pages 689~694
DOI : 10.5143/JESK.2011.30.6.689
Objective: The aim of this study is to evaluate the fluctuation of signal amplitude during repetitive dynamic contraction based on surface electromyography(EMG). Background: The most previous studies were considered isometric muscle contraction and they were difference to smoothing window length by moving average filter. In practical, the human movement is dynamic state. Dynamic EMG signal which indicated as the nonstationary pattern should be analyzed differently compared with the static EMG signal. Method: Ten male subjects participated in this experiment, and EMG signal was recorded by biceps brachii, anterior/posterior deltoid, and upper/lower trapezius muscles. The subject was performed to repetitive right horizontal lifting task during ten cycles. This study was considered three independent variables(muscle, amplitude processing technique, and smoothing window length) as the within-subject experimental design. This study was estimated muscular activation by means of the linear envelope technique(LE). The dependent variable was set coefficient of variation(CV) of LE for each cycle. Results: The ANOVA results showed that the main and interaction effects between the amplitude processing technique and smoothing window length were significant difference. The CV value of peak LE was higher than mean LE. According to increase the smoothing window length, this study shows that the CV trend of peak LE was decreased. However, the CV of mean LE was analyzed constant fluctuation trend regardless of the smoothing window length. Conclusion: Based on these results, we expected that using the mean LE and 300ms window length increased reproducibility and signal noise ratio during repetitive dynamic muscle contraction. Application: These results can be used to provide fundamental information for repetitive dynamic EMG signal processing.
The Effects of Coordinated Upper-limb Postures of Back, Shoulder, and Elbow Flexion Angles on the Subjective Discomfort Rating, Heart Rate, and Muscle Activities
Kong, Yong-Ku ; Lee, Soo-Jin ; Lee, Kyung-Suk ; Seo, Min-Tae ;
Journal of the Ergonomics Society of Korea, volume 30, issue 6, 2011, Pages 695~703
DOI : 10.5143/JESK.2011.30.6.695
Objective: This study was to investigate the effects of coordinated upper-limb body postures on the subjective discomfort rating, heart rate, and muscle activities. Background: Although generally many checklists such as OWAS, RULA, and REBA were applied to evaluate various body postures, the body postures were might be overestimated or underestimated because each body part(i.e., back, shoulder, and elbow etc.) was evaluated separately, and then added all rates of individual body parts to assess an overall risk level for the body posture in these methodologies. Methods: A total of 20 participants maintained 14 postures which were combinations of back, shoulder, and elbow flexion angles and then muscle activities, subjective discomfort, and heart rates were collected every three minute during a sustained 15 minute and 0.5kg weight holding task. Four muscle groups were investigated: erector spine, anterior deltoid, upper trapezius, triceps brachii. Results: Results showed that subjective discomfort was the lowest when the angle of back and shoulder were both
, while the body posture with
of back angle and
shoulder angle was rated as the most subjective discomfort posture. In general, the subjective discomfort ratings increased as back and shoulder flexion angles increased. It was noted that, however, the subjective discomfort of body posture with a
back angle and
shoulder flexion angle was lower than that of body posture with a
shoulder flexion angle. The research findings of heart rates and muscle activities showed similar results for the analyses of subjective discomfort ratings. Conclusions: The possible limitations of the current ergonomics evaluation techniques which assessing a body posture with summing all body part score after individually analyzed in this study. Based on the analyses of subjective discomfort, heart rate, and muscle activities, it was recommended that a use of effects of coordinated upper-limb body postures would be considered when one evaluates work-load for various working postures. Application: These findings can be used for developing a more accurate assessment checklist for working posture as well as preventing musculoskeletal disorders of workers in workplaces.
Discrimination of Three Emotions using Parameters of Autonomic Nervous System Response
Jang, Eun-Hye ; Park, Byoung-Jun ; Eum, Yeong-Ji ; Kim, Sang-Hyeob ; Sohn, Jin-Hun ;
Journal of the Ergonomics Society of Korea, volume 30, issue 6, 2011, Pages 705~713
DOI : 10.5143/JESK.2011.30.6.705
Objective: The aim of this study is to compare results of emotion recognition by several algorithms which classify three different emotional states(happiness, neutral, and surprise) using physiological features. Background: Recent emotion recognition studies have tried to detect human emotion by using physiological signals. It is important for emotion recognition to apply on human-computer interaction system for emotion detection. Method: 217 students participated in this experiment. While three kinds of emotional stimuli were presented to participants, ANS responses(EDA, SKT, ECG, RESP, and PPG) as physiological signals were measured in twice first one for 60 seconds as the baseline and 60 to 90 seconds during emotional states. The obtained signals from the session of the baseline and of the emotional states were equally analyzed for 30 seconds. Participants rated their own feelings to emotional stimuli on emotional assessment scale after presentation of emotional stimuli. The emotion classification was analyzed by Linear Discriminant Analysis(LDA, SPSS 15.0), Support Vector Machine (SVM), and Multilayer perceptron(MLP) using difference value which subtracts baseline from emotional state. Results: The emotional stimuli had 96% validity and 5.8 point efficiency on average. There were significant differences of ANS responses among three emotions by statistical analysis. The result of LDA showed that an accuracy of classification in three different emotions was 83.4%. And an accuracy of three emotions classification by SVM was 75.5% and 55.6% by MLP. Conclusion: This study confirmed that the three emotions can be better classified by LDA using various physiological features than SVM and MLP. Further study may need to get this result to get more stability and reliability, as comparing with the accuracy of emotions classification by using other algorithms. Application: This could help get better chances to recognize various human emotions by using physiological signals as well as be applied on human-computer interaction system for recognizing human emotions.
Development of Simple Articulated Human Models using Superquadrics for Dynamic Analysis
Lee, Hyun-Min ; Kim, Jay-Jung ; Chae, Je-Wook ;
Journal of the Ergonomics Society of Korea, volume 30, issue 6, 2011, Pages 715~725
DOI : 10.5143/JESK.2011.30.6.715
Objective: This study is aimed at developing Articulated Human Models(AHM) using superquadrics to improve the geometric accuracy of the body shape. Background: The previous work presents the AHM with geometrical simplification such as ellipsoids to improve analysis efficiency. However, because of the simplicity, their physical properties such as a center of mass and moment of inertia are computed with errors compared to their actual values. Method: This paper introduces a three steps method to present the AHM with superquadrics. First, a 3D whole body scan data are divided into 17 body segments according to body joints. Second, superquadric fitting is employed to minimize the Euclidean distance between body segments and superquadrics. Finally, Fee-Form Deformation is used to improve accuracy over superquadric fitting. Results: Our computational experiment shows that the superquadric models give better accuracy of dynamic analysis than that of ellipsoid ones. Conclusion: We generate the AHM composed of 17 superquadrics and 16 joints using superquadric fitting. Application: The AHM using superquadrics can be used as the base model for dynamics and ergonomics applications with better accuracy because it presents the human motion effectively.
A Study on the Lower Body Somatotype Characteristics of 20~59 Aged Women by Age Groups
Lee, Mi-Sung ; Kim, So-Ra ;
Journal of the Ergonomics Society of Korea, volume 30, issue 6, 2011, Pages 727~737
DOI : 10.5143/JESK.2011.30.6.727
Objective: This study aimed to analyze somatotype characteristics of the women of 20's, 30's 40's and 50's and thus to provide the basis for developing pants patterns by the age groups. Background: Despite many previous researches for the somatotype characteristics of adult women, few studies have considered age groups. Method: The data of the
anthropometry by Size Korea were analyzed for the purpose. The 32 direct body measurements and the 32 indexes of 2,213 women aged 20~59 were analyzed. In order to compare somatotype characteristics among the age groups, an ANOVA and a Tukey test were used. Results: The women in 20's were the tallest among the age groups, and had the smallest waist circumference and hip circumference. Their waist breadths were also the narrowest. They had a slim and long body type but their calves were relatively thick. The 30's women were smaller, shorter with the height and length items than the 20's were. They were bigger, wider and deeper with the circumference, breadth and depth items than the 20's were and they were heavier. On the other hand, their hip circumference and crotch length were in the same group as the women in 20's. The crotch length(omphalion) of the 40's women was the longest among all the age groups and the crotch length(natural indentation) of the 40's women was in the same as the women in 50's. The women in 50's were the smallest and heaviest among all the age groups. The difference between their hip circumferences and waist circumferences was the smallest. They had an obese abdomen and sagged hips. Conclusions: The somatotype characteristics of the age groups were significantly different, and thus it is suggested to develop skirt and pants patterns for each age group. Application: The skirt and pants patterns for the somatotype characteristics of the women by age groups will be developed through the body feature data of this study.
Evaluation of Information Presentation Methods for a Wearable Braille Display
Jung, Ki-Hyo ; Lee, Min-Jeong ; Chang, Joon-Ho ; You, Hee-Cheon ;
Journal of the Ergonomics Society of Korea, volume 30, issue 6, 2011, Pages 739~747
DOI : 10.5143/JESK.2011.30.6.739
Objective: The present study evaluated information presentation methods applicable to a wearable Braille display in terms of performance and satisfaction measures. Background: A Braille display wearable at a finger can improve accessibility of information for the blind by presenting information in real time. Method: A Braille display with six pins operated by DC servomotors was developed to simulate four information presentation methods(active, stationary, simultaneous, and sequential methods). An evaluation experiment was conducted with 16 participants(8 normal and 8 blind participants) by using three objective measures(reaction time, RT, unit: sec; recognition time, CT, unit: sec; correct response percentage, CP) and two subjective measures(overall satisfaction, OS; perception easiness, PE) with a 7-point scale. Results: The average RTs and CTs of the active and stationary methods were significantly shorter than those of the simultaneous and sequential methods for the blind participants. Also, the average CPs, OSs, and PEs of the active and sequential methods were significantly higher than those of the stationary and simultaneous methods. Conclusion: The active and sequential methods were preferred to the other methods for the blind. Application: The performance characteristics identified in the present study for the four braille display methods can be utilized to develop an effective wearable Braille display system.
Prevention of Work-related Musculoskeletal Disorders in Grapes Pinching by Using Electro-motion Scissors Designed Ergonomically
Chae, Hye-Seon ; Kim, Sung-Cheol ; Kim, Kwan-Woo ; Lee, Kyung-Suk ; Kim, Hoy-Cher ; Park, Keun-Sang ;
Journal of the Ergonomics Society of Korea, volume 30, issue 6, 2011, Pages 749~755
DOI : 10.5143/JESK.2011.30.6.749
Objective: The purpose of this study is to assess the reducing effect of workload on developed electro-motion scissors. Methods: To achieve this, we measured the pressure distribution, Joint angle of fingers and JSI(Job Strain Index) for electro-motion scissors and hand-operated scissor in objective assessment and surveyed the uncomfortable degree in subjective assessment. Results: As a result, The peak of pressure in the electro-motion scissors was generally lower than the hand-operated scissors. JSI and overall joint angle of fingers for the electro-motion scissors were remarkably lower than the hand-operated scissors. Also, the subjective uncomfortable degree showed that the uncomfortable point of electro-motion scissors were generally lower than the hand operated scissors. Conclusion: The impact of reducing the work load as well as distributing the pressure around the hand by using electro-motion scissors during grapes pinching was confirmed.
Suggestion of Model Change Work Improvement by REBA and Therblig
Lee, Sung-Koon ; Park, Peom ;
Journal of the Ergonomics Society of Korea, volume 30, issue 6, 2011, Pages 757~764
DOI : 10.5143/JESK.2011.30.6.757
Objective: The aim of this study was to provide a method to improve the compliance and reduce the time by reducing the workload during the model change work. Background: The enterprises are constructing the small quantity batch production system by increasing the number of model change and reducing model-changing. However, the compliance is low because the work is strenuous and high skills are needed, so the system management is facing with many difficulties. Method: After classifying the model change work according to the purposes(preparation, change and adjustment) with the target of mascara filling machine, element tasks time were measured and the motion analysis(therblig symbol) and REBA analysis were performed. The study incorporated 3 independent variables as the number of motion, REBA score and the element time. The dependent variable is the type of element work as preparation, change and adjustment. The statistical test was performed by one-way ANOVA(
< 0.05). Results: For the preparation, the number of motions appeared in the order of Use(U), Transport Loaded(TL), and Position(P). The order appeared in change is Use(U), Release Load(RL), and Grasp (G). The adjustment appeared in the order of Position(P) and Use(U). The results of average motion time as the element work times divided by the number of motion appeared in the order of adjustment(1.85sec/motion), preparation(1.11sec/motion), and change(0.62sec/motion). The results of REBA showed that the average risk level of change and adjustment were medium, but 53.1% of change and 42.9% of adjustment were evaluated as high. Conclusion: Reducing the avoidance and improving the compliance of work could be expected if the job autonomy were improved by improving the working postures with high risk level. Application: It is expected to solve the problem of reducing the time of model change work in the small quantity batch production system. The future work is to carry out the improvement directions found in the results and compare the results after improvement.
An Exploration of Various Evaluation Methods to Improve Usability of Museum Mobile Device
Ahn, Mi-Lee ; Cha, Hyun-Jin ; Hwang, Yun-Ja ; Kim, Hee-Jin ;
Journal of the Ergonomics Society of Korea, volume 30, issue 6, 2011, Pages 765~773
DOI : 10.5143/JESK.2011.30.6.765
Objective: This study aims towards exploring a model of the HCI evaluation methods to improve the usability of mobile device, based on a case of a Mobile PDA system in a Museum context. Background: Mobile PDA systems in a Museum context is widely utilized for the educational purposes, but it is criticized for low usability that the device only play a role in textbooks on legs without any interactive educational activities. Therefore, the usability improvements on the mobile PDA system should be considered. Method 1: This model was developed with a combination of the expert review and the user testing, and with a combination of the qualitative and quantitative studies. In more details, first of all, a qualitative study was conducted as a combination of three different methods: 1) expert review with heuristics, 2) interviews with persons working in a museum, and 3) contextual enquiry. Results 1: The experts review provided with critical usability issues, and the semi-constructive interview helped to understand the background of the mobile device. Lastly, the contextual enquiry showed user experience problems and directions of improving the device from user's perspective. Method 2: Based on the results of the qualitative study, a questionnaire was designed. Results 2: The analysis of the quantitative study was conducted to generalize the problems, and prioritize the direction of improving the device within the limitation of the cost and time in a museum. Conclusion: This study has implications in developing an example of a HCI evaluation model to improve the user experience of the mobile device as well as finding problems and directions of how to improve the mobile PDA systems in the museum. Application: In fact, most of the studies related to the evaluation of the mobile device have been conducted in a laboratory context due to the cost and time. This paper, however, attempted to apply to various HCI research techniques from different constituents in real context.