• Journal of the Korean Society of Safety
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• v.20 no.4 s.72
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• pp.148-153
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• 2005

Computer dominated jobs and industrial automation have rapidly created work-related musculoskeletal disorders(WMSDs) and WMSDS are expanding to employee of other general industry. Specific risk factors associated with WMSDs include repetitive motion, heavy lifting, forceful exertion, contact stress, vibration awkward posture and rapid hand and wrist movement. The purpose of this paper is to analyze the effects of the neck muscle workload according to posture(joint angle) and load weight. Seven male students participated in this study. To analyze neck muscle workload was studied on electromyographic(EMG) activity for sternocleidomastoid and trapezius, was subjectively rated using a Borg's CR-10 scale. ANOVA showed that the CR-10 ratings and most EMG root-mean-square (RMS) value were statistically significant improvement according to posture(joint angle) and load weight. The results of this study indicate the joint angle and weight of neck muscle workload to provide safe working conditions. To reduce the large number and severity of WMSDs employees have been experiencing, we need to redesign the job in workplace to identify and control hazards that are reasonably likely to be causing or contributing to the WMSDs.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.81-87
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• 2013

Crane operators usually work with their necks bent forward in a seating position for a long period. They have complained of their musculoskeletal stress at their necks. The objective of this study was to find the level of stress at the neck when crane operators bend their neck forward during their work. Experiments were conducted in the laboratory where subjects bent their necks forward for 1 minute and took a rest for 0.5 minute and repeated this performance for 60 minutes. Subjective evaluation using Borg's CR-10 scale and electromyography (EMG) were used to check the level of the stress at the neck. Subjects reported that the level of pain at the end of 60 min. experiment was close to the extreme pain(level 8.95). The EMG level(amplitude) increased 80% on the average and the center frequency of EMG shifted to the lower frequency level which indicated fatigue of neck muscles. Thus, it was found that there is quite much neck stress for crane operators when they maintain their neck posture of bending forward for a long time during their work. This information will be a basis in searching for an intervention measure for the crane operators' neck stress.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.2
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• pp.133-139
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• 2019

Purpose : This study aims to investigate the rating of perceived exertion (RPE) and muscle activity of the inspiratory primary and accessory muscle during breathing exercise with different air hole diameters of the inspiratory muscle trainer (IMT). Methods : The Borg's scale and surface electromyography (EMG) was used to collect data of the RPE and muscle activity of the inspiratory primary the external intercostal (EI) and diaphragm (DIA) and accessory muscles anterior scalene (AS), sternocleidomastoid (SCM), pectoralis major (PM), and upper trapezius (UT) muscles during breathing exercise with different air hole diameters (6 mm, 4 mm, and 2 mm) of the IMT in healthy young male subjects. Results : The RPE and muscle activities of the AS, SCM, and UT are increased significantly in accordance to the decreasing diameter of air hole of air tip in IMT. However, there are no differences in the muscle activities of the PM, EI, and DIA based on differences of diameters of air hole of air tip in IMT. Conclusion : The smaller the diametr of IMT air-hole, RPE and muscle activities of AS, SCM and UT were increased. Therefore, further study would be necessary to investigate the proper intensity and relaxation posture for the exercise protocol to strengthen the inspiratory primary muscles.

• Journal of Korean Academy of Medicine & Therapy Science
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• v.10 no.2
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• pp.73-80
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• 2018

Objective: We developed an ergonomic pruning shears that allows the user to freely adjust the width of the grip and conducted this study to examine the effects of the pruning shears on grip strength and the fatigue of the fingers. Method: The maximum grip strength was first measured with an digital dynamometer, and the maximum grip strength was measured again after the subjects repeated scissoring 100 times using general pruning shears or ergonomic pruning shears. Borg's CR-10 scale was used to measure subjective fatigue after using the two pruning shears. Results: When the grip strength values after using the two pruning shears were compared with each other the mean grip strength after using ergonomic pruning shears was 27.69 kg, which was higher than that after using general pruning shears, 25.73 kg (p<.05). The subjective fatigue when the two pruning shears were used was shown to be 3.6 points for general pruning shears and 1.73 points for ergonomic pruning shears (p<.05). Conclusion: After repeating scissoring 100 times, the fatigue of the fingers was lower when ergonomic pruning shears were used than when general pruning shears were used and grip strength was higher when ergonomic pruning shears were used than when general pruning shears were used.

• Fashion & Textile Research Journal
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• v.19 no.4
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• pp.504-514
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• 2017

Discomfort as well as muscular pain and musculoskeletal diseases occur in cases of stressed posture due to prolonged pressure. Therefore, the American Academy of Orthopaedic Surgeons (AAOS) and Pediatric Orthopaedic Society of North America (POSNA) recommend that bags that weigh no more than 15 - 20% of the wearer's weight. However, despite the prolonged pressure from using baby carriers, there are no recommendations and limited studies on how to protect wearers. Therefore, this study investigates subjective fatigue according to the usage of waist support and hip seat. Based on this, muscle fatigue and secondary subjective fatigue according to three types of currently commercial baby carriers (X-type, H-type, and H-hip type) were measured. Subjective comfortability was evaluated on a 5 point Likert-scale and subjective fatigue was evaluated on Borg's CR-10 scale. Objective muscle fatigue was also compared by measuring and analyzing electromyogram (EMG). The results of primary subjective fatigue showed statistically significant changes in the shoulders, waist, calves, and soles of the feet according to the usage of hip seats and waist support. Electromyogram measurements also showed less muscle fatigue at the upper trapezius muscle and thoracic erector spine muscle for the H-hip seat baby carrier, which has both waist support and hip seat, compared to an X-type baby carrier, which has neither. However, results of subjective fatigue showed opposite results at the waist despite having same results at the shoulders and beneath the shoulders. This show discrepancies between objective muscle fatigue and subjective fatigue; therefore, that both aspects must be taken into consideration when developing ergonomic baby carriers.

• Journal of Life Science
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• v.21 no.1
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• pp.9-14
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• 2011

Perceived exertion involves detection and interpretation of sensations arising from the body during physical exercise. Physiological variables such as heart rate and oxygen consumption positively correlate with ratings of perceived exertion (RPE). It is unknown whether the accuracy of predicting exercise intensity from RPE differs between men and women. Therefore, it was examined whether men or women could predict relative exercise intensity, determined by oxygen consumption, more accurately from RPE. Ten male and ten female young adult subjects aged 25.1${\pm}$3.52 yr volunteered to participate. RPE were determined by the Borg 15-category scale, and a standard Bruce treadmill protocol was used to perform graded exercise testing. There was no significant difference in slope means between males and females (p=0.501). No significant difference was observed when plotting rates of perceived exertion (RPE) vs. percentage of $VO_2$ max. The relative maximal oxygen consumptions ($VO_{2max,\;}_{rel}$) were 52.36${\pm}$7.35 ml/kg/min for males and 41.44${\pm}$6.71 ml/kg/min for females, respectively and there was a significantly high difference between the two groups in the relative $VO_{2max}$, as well as figures of 4.05${\pm}$0.36 l/min for males and 2.53${\pm}$0.39 l/min for females in the absolute $VO_{2max}$ in this study. There were no significant differences in slope, y-intercept, and standard error of estimate (SEE) between males and females. No significant difference with RPE according to exercise intensity was found between males and females. However, RPE was a useful predictor of exercise intensity in independent genders.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.1
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• pp.1-10
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• 2017

The difficulties in opening and closing a sport utility vehicle (SUV) tailgate is important aspect of JD (James David) power's Initial Quality Survey (IQS) assessment, and affective quality has a big impact on the the success of thesedays products. The purpose of this study is to evaluate the perceived difficulty and satisfaction of customers by the opening and closing of the tailgate and to grasp the relationship between them and the opening and closing reaction force. The mechanical force required to open and close 42 domestic and overseas SUV tailgates was measured with the help of an auto company. In the experiment, 100 male drivers in their 20s to 50s evaluated perceived difficulty and satisfaction with opening and closing the tailgate. The results of the analysis showed that perceived difficulty and satisfaction were statistically different depending on the vehicle, but did not depend on the personal characteristics of the participants. The perceived difficulty and satisfaction regression model of tailgate opening and closing was developed by mechanical force variables and had a relatively high adjusted $R^2$ ranging from 0.62 to 0.73. The models showed that the the initial close and open force, the difference between initial and maximum close force and the difference between initial and auto-fall angle should be small for the low perceived exertion and high satisfaction. In addition, the correlation analysis between IQS score of tailages and perceived difficulty and satisfaction showed that the IQS scores were more related to the perceived difficulty and satisfaction of closing than those of opening. The results of the study will be helpful to design and test mechanical open and close structure of SUV tailgates.

• Korean Journal of Applied Biomechanics
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• v.29 no.3
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• pp.197-204
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• 2019

Objective: The purpose of this study was to identify the effect of high-heels (HH) modification on metatarsal stress in female workers. Method: Seven females who work in clothing stores ($heights=160.4{\pm}3.9cm$; $weights=47.4{\pm}4.1kg$; $age=31.3{\pm}11.1yrs$; $HH\;wear\;career=8{\pm}6.5yrs$) wore two types of HH (original and modified). The modified HH had been grooved with 1.5 cm radius and 0.2 cm depth around the first metatarsal area inside of the shoes using the modified shoe-last. Participants were asked to walk for 15 minutes on a treadmill and to stand for 10 minutes with original and modified HH, respectively. Kinetics data were collected by the F-scan in-shoe system. After each test, participants were asked to rate their perceived exertion using the Borg's 15-grade RPE scale and interviewed about their feeling of HH. Nonparametric Wilcoxon signed-rank test and effect size (Cohen's d) were used to determine the difference of the variables of interest between the original and modified HH. Results: In the present study, modified HH of the peak contact pressure of 1st metatarsal (PCP) left, PCP right, pressure time integral (PTI) left, peak pressure gradient (PPG) left during standing and PPG right during walking are greater than original HH. And even it didn't show statistically significant, the average in all pressure values of modified HH showed bigger than original HH. It surmised to be related to awkward with modified HH. Even though they said to feel the comfortable cause of big space inside of HH in the interview, they seemed to be not enough time to adapt with new HH. So their walking and standing postures were unstable. Conclusion: Modified the fore-medial part of HH can reduce the stress in the first metatarsal head and big toe area during standing and walking.

• The Korean Journal of Rehabilitation Nursing
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• v.10 no.2
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• pp.108-115
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• 2007

Purpose: This study was to investigate the effects of respiratory rehabilitation training on the respiratory functions of hospitalized cervical spinal cord injury patients. Methods: One group pre and post test design was used. Subjects were 20 cervical spinal cord injury inpatients of the national rehabilitation center. Training program consisted of air cumulation training, manual assisted coughing training, and abdominal breathing. Trained rehabilitation nurse implemented 20 minutes program twice a day for 4 weeks. Respiratory function was measured as peak coughing flow rate, and perceived respiratory difficulty after activity on wheel chair for 30 minutes and during speaking and singing. Perceived respiratory difficulty was measured with modified Borg scale. Also content analysis was done with the result of open ended question about subjective feeling about training. All variables were measured 3 times before, 2weeks and 4 weeks after the program. Results: Peak coughing flow rate significantly improved after compared to before training. Also all three perceived respiratory difficulty variables decreased significantly after training. In the content analysis, 'it's easier to cough up phlegm' was the most frequent answered subjective feeling. 'Sound at speaking and coughing became louder', 'respiratory volume increased', and 'comfortable chest feeling' were frequent answered subjective feeling, in order. Conclusion: Although it is preliminary since no control group, respiratory rehabilitation training was found to be effective to improve respiratory function in terms of peak coughing flow rate, perceived respiratory difficulty, and subjective feeling. It is necessary further systemic research to investigate the effects of respiratory rehabilitation training.

• Journal of the Ergonomics Society of Korea
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• v.28 no.4
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• pp.35-49
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• 2009

This study investigated perceived discomforts and those reasons of the young and middle-aged, the aged, the disabled and the pregnant in various daily activities, and elicited universal design factors based on human capacities (physical, sensory, cognitive and affective). A total of eighty people (twenty subjects for each user group) participated in one-to-one interviews about thirty six items of daily activities. A degree of discomfort of the daily activities was measured using Borg's CR10 scale. As a result, the disabled and the pregnant complained about almost all of the daily activities, and their degrees of discomforts were significantly higher than those of the youth and middle-aged and the aged. However, the youth and middle-aged and the aged only complained about some specific items. The major reasons of discomforts were related to physical and affective capabilities in general, where the detailed reasons of each user group were comparatively different. Finally, the universal design factors were elicited for each daily activity item based on the results of each user group. This study can be used to understand the discomforts and characteristics of the aged, the disabled and the pregnant in the various daily activities. The universal design factors elicited can also be applied to design related products and facilities universally.