• Journal of the Ergonomics Society of Korea
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• v.27 no.3
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• pp.81-92
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• 2008

Musculoskeletal disorder (MSD) problems have been increasingly reported in hospital sector but the problems were not addressed with respect to holistic aspects of the target population in Korea. Often, it is required to understand how MSD symptoms are associated with factors such as personal, work environmental and psychosocial stressors. To examine features of association between sets of MSD symptoms and the factors, a questionnaire survey was conducted in a university hospital. A 140-item questionnaire was developed and used for collecting information including factors (e.g., job/occupation, task/activity, job stress) and MSD symptoms. A total of 1,091 workers (male 23.7% and female 76.3%) were finally determined for data analyses. Prevalence rate for the whole body was 72% and, among body parts, the highest was 48.7% for the shoulder, followed by 34.6%(the low back), 32.7%(the leg/foot), 27.9%(the neck), 26.7%(the wrist) and 12%(the elbow). The symptoms were significantly different by job/occupational variable in each of all body parts except the neck. The symptoms were very significantly different by task/activity variables in each of all body parts while those symptoms were significantly different by psychosocial variables, depending on body part and gender. In the logistic regression analyses performed for MSD symptoms by body part and each of 3 factors, odds ratio values varied, ranging from 0.7 to 3.3. The controls for reducing the symptoms were discussed on the basis of the findings. The results show that the MSD symptoms can remarkably vary by the factors and, in particular, can be highly differential for the task/activity factor. This study suggests that MSD symptom features be examined by using various factors and then a higher differential factor be primarily utilized for controling MSD symptoms in general industry including hospital settings.

• Physical Therapy Rehabilitation Science
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• v.9 no.2
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• pp.74-81
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• 2020

Objective: To prevent low back pain, an objective evaluation tool to evaluate pelvic mobility and exercise to improve the flexibility of the lumbar region is needed. The purpose of this study was to compare the results of pelvic mobility measurements using the Wii Balance Board (WBB) and Sensbalance Therapy Cushion (STC), evaluate the usefulness of the STC as a tool for measuring pelvic mobility. Design: Cross-sectional study. Methods: Fifty healthy subjects participated in this study. The subjects performed pelvic mobility range, proprioception, reaction time and reach of the arm using the STC. The pelvic movement parameter was measured two times to determine the intra-rater reliability. To measure the correlation between lumbar muscle tension and pelvic mobility, Myovision was used to measure tension of L4, L5 level erector spinae muscle. Correlations between measured variables were checked to determine the validity of the pelvic mobility assessment tool. Results: STC showed high test-retest reliability in pelvic tilt measurement and reaching task [intraclass correlation coefficients (3,1)=0.804-0.915]. The relationship between WBB and STC showed a significant positive correlation with the pelvic tilt and reaching task (p<0.05). Posterior tilt and erector spinae activation (Lt. L5) showed a significant negative correlation (p<0.05). Left, right tilt and erector spinae activation (L5) showed a significant negative correlation (p<0.05). Conclusions: This study confirmed the advantages of the STC and found efficiency as an objective measuring device of pelvic mobility.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.1-23
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• 1998

Work-related Low Back Pain(LBP) is one of tile most important Issues in the field of industrial safety and health. Particularly, manual lifting is known as a major cause of work-related LBP and impairment. Total number of 163 manual lifting tasks in motor assembly processes were investigated. The 1981 and the 1994 equations developed by National Institute for Occupational Safety and Health(NIOSH) were applied to evaluate potential hazards of lifting-related LBP. Comparisons between the 19R I and 1994 NIOSH criteria were made. The relationships between the NIOSH criteria and lifting-related LBP were also analyzed. The results of this study are as follows: 1. The values of Action Limit(AL) by the NIOSH 1981 lifting equation. Recommended Weight Limit(RWL) by the 1994 equation and the weight of the load handled at each manual lifting task were shown log-normal distributions. 2. LI'(the weight of tile load/AL) and LI(the weight of the load/RWL) were calculated estimate the physical stress imposed by each individual lifting task. As a result. 76.7% of the total LI' value exceeded 1 and 12.9% exceeded 3, and 84.7% of the total LI values exceeded 1 and 20.9% exceeded 3. 3. Bus 2 Department showed the highest rate of LI'>1 and LI>1 and Bus 1 Department showed the highest rate of LI'>3 and LI>3 4. In general, the RWLs by the 1994 equation were found lower than the ALs by the 1981 equation. It is assumed to he resulted from the fact that the 1994 equation includes methods evaluating asymmetrical lifting tasks and lifts of objects with less then optimal hand-container couplings, and also covers a larger range of work durations and lifting frequencies than the 1981 equation. 5. Significant correlations were found between LI' and incidence of LBP (R=0.734, p<0.05). LI and incidence of LBP(R=0.671. p<0.10) and load-weights and incidence of LBP(R=0.797, p<0.05). 6. Control measures are required to achieve the value of LI less than 1 for some tasks having high LI values. Engineering control is highly recommended for some tasks having the value of LI above 3.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.3
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• pp.176-182
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• 2005

American Conference of Governmental Industrial Hygienists (ACGIH) adopted the Lifting Threshold Limit Values ($TLVs^{(R)}$) in 2005 as a guideline for protecting the workers from work-related low back and shoulder disorders associated with repetitive lifting tasks. The TLVs consist of three tables with recommended weight limits for lifting tasks and their determination procedures are simple. The TLVs sans the material weight/the recommended values (LITLVs) were obtained from 45 lifting tasks in ship engine manufacturing factories. These values were compared and correlated with the Recommended Weight Limits (RWLs) and lifting indices (LIs) determined by the Revised Lifting Equation (LE) of the National Institute for Occupational Safety and Health (NIOSH). The average ratio, LITLVs/LIs, was 0.8 (LITLVs: $1.3{\pm}0.8$, LIs: $1.6{\pm}0.7$). Thus, the TLVs underestimated the risk than the LE. The LITLVs were highly correlated with LIs (r=0.82). The predicted value of LITLVs when LIs=1 wa 0.76. Using the predicted TLVs the higher risk ones of a large number of tasks can be screened to be further investigated.

• Journal of the Ergonomics Society of Korea
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• v.29 no.3
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• pp.279-286
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• 2010

The purpose of this study was to compare the electromyographic(EMG) activities of trunk and hip muscles between right and left sides while subjects performed prolonged manual task in asymmetric and symmetric weight-bearing posture. Fifteen healthy male college students were recruited for this study. The subjects were asked to perform bimanual upper extremity task for 6 minutes in two different standing postures. In the symmetric weight-bearing posture, the subjects were standing with evenly distributed body weights to both legs. In the asymmetric weight-bearing posture, the subjects distributed about 90% of their body weight onto their preferred(supporting) leg and 10% of their body weight onto the opposite leg while they were standing. EMG activities of the right and left internal oblique, erector spinae, gluteus maximus, and gluteus medius were measured and normalized as % MVIC. Then the EMG data were statistically analyzed using paired t-tests. The EMG activities of all measured muscles were not significantly different between the right and left side in the symmetrical weight-bearing posture(p>0.05). However, the EMG of the supporting side internal oblique was significantly lower than the opposite side(p<0.05), and the EMG of the erector spinae, gluteus maximus, and gluteus medius were significantly greater on the supporting side(p<0.05). The results of this study support that unbalanced use of right and left muscle possibly causes the changes in muscle length which results in asymmetry of trunk and hip muscles. Furthermore, the uneven weight support onto right and left legs will cause a distortion of viscoelastic ligaments around hip and sacroiliac joints in the long run. Further studies to determine the effect of various manual tasks on the trunk and hip muscles as well as the effect of asymmetrical weight-bearing standing posture on hip and back muscle fatigue may be required.

• Fashion & Textile Research Journal
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• v.20 no.6
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• pp.704-712
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• 2018

This study analyzed working postures using the Ovako Working Posture Analysis System (OWAS) to improve work clothes for construction workers. A video taken at a construction work site was stopped at regular intervals and the postures of relevant body parts proposed by OWAS was recorded. Additionally, based on analysis of the working postures code, the level of work action for each postures was classified from stage I to IV. General workers frequently straightened or bent forward at the waist, and used their legs to stand, bend, or walk. Wood workers moved extensively from the waist, keeping their legs relatively straight and their arms held below their shoulders, repeatedly tapping with a hammer weighing less than 10.0kg. Rebar bending workers mainly bent forward at the waist, with both legs bent or standing with one leg bent. Rebar transport and fixing workers walked with the waist straight, and occasionally one or both hands held above the shoulders. Their work also involved holding a hook, which weigh less than 10.0kg, in their hands, and the difficult task of lifting and placing long rebars, which weigh from 10.0 to 20.0kg or more. Concrete pouring workers bent or twisted their back to the side. Therefore, this study suggests that design goals should be different when developing workwear for each type of worker.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.4
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• pp.541-550
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• 2012

PURPOSE: The purpose of this study was compare quadriceps femoris muscle activity while performing wall slide squats of four methods. METHODS: Forty subjects, with no history of patellofemoral pain, quadriceps injury, or other knee injury volunteered for this study. Muscle activation of the vastus medialis obliquus, rectus femoris, vastus lateralis muscles were recorded while subjects performed 10 consecutive wall slide squats. Subjects performed the wall slide squats during four different methods: (1) basic wall slide squat, (2) keep back upright against fitness ball, (3) standing of unstable surface, (4) squeezing ball between both knees. Statistical analysis were accomplished by utilizing the one-way ANOVA(Bonferroni's post-hoc test) by SPSS 20.0 program. Significance level was set at p<.05. RESULTS: Muscle activations induced wall slide squats of four methods compared and results showed that there was significant difference only in vastus medialis obliquus and rectus femoris but there was no significant difference in vastus lateralis. The vastus medialis obliquus was significantly different only keep back upright against fitness ball at post-hoc test. The rectus femoris was significantly different keep back upright against fitness ball and standing of unstable surface at post-hoc test. CONCLUSION: Based on these results, we conclude that quadriceps femoris muscle activations are differenced by performing wall slide squats of four different methods in healthy subjects. These data suggest that for quadriceps muscle strengthening, exercise professionals can perform the wall slide squats by altering several task variables. Further research is needed to determine the exact mechanism by which quadriceps function is altered.

• Safety and Health at Work
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• v.6 no.4
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• pp.329-337
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• 2015

Background: The aim of this study is to examine the prevalence of musculoskeletal complaints in Swiss operating room (OR) nurses, and to investigate how work-family conflict, work interruptions, and influence at work are related to lumbar and cervical back pain. Methods: Participants in this correlational questionnaire study included 116 OR nurses from eight different hospitals in Switzerland. Results: We found that 66% of the OR staff suffered from musculoskeletal problems. The most prevalent musculoskeletal complaints were lumbar (52.7%) and cervical pain (38.4%). Furthermore, 20.5% reported pain in the mid spine region, 20.5% in the knees and legs, and 9.8% in the hands and feet. Multiple linear regression analyses showed that work-family conflict (p < 0.05) and interruptions (p < 0.05) significantly predicted lumbar and cervical pain in OR nurses, while influence at work (p < 0.05) only predicted lumbar pain. Conclusion: These results suggest that reducing the work-family conflict and interruptions at work, as well as offering opportunities to influence one's workplace, help to promote OR nurses' health.

• Journal of dental hygiene science
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• v.9 no.5
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• pp.545-550
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• 2009

This study set out to examine the knowledge about and preventive actions against musculoskeletal diseases among dental hygiene students according to the Health Belief Model, suggest a need for programs to promote health and prevent those diseases, and investigate their relations, A survey was taken among 83 sophomores and 114 juniors at the dental hygiene major of a college in Gyeonggi Province. Analyzed by using SAS 8.0 version. The findings are as follows: 1. The sophomores and juniors scored $22.50{\pm}2.37$ and $22.29{\pm}3.01$ points, respectively, on susceptibility of the Health Belief Model with significant differences between the two groups(P < 0.01). Significant differences were also found between the sophomores that scored $18.82{\pm}2.60$ points and the juniors that scored $18.64{\pm}2.77$ points on benefit(P < 0.05). 2. The juniors experienced a higher level of pain than the sophomores with statistical significance observed on the neck, shoulder, lower back, knee, foot, and ankle(P < 0.05). 3. Of the Health Belief Model, severity had significant positive correlations with 'Placing frequently used tools near the dental technician' and 'Trying to avoid repeating the same task and diversify tasks'(P < 0.01). And benefit was positively correlated with 'Trying to reduce the frequency of bending and stretching out during treatment, 'Trying not to lean much with the neck, back, arm, and wrist' and 'Trying to maintain the torso in the neutral position'(P < 0.01). The results suggest that there should be some instructions to help dental hygiene students practice the preventive actions against musculoskeletal diseases and further prevention programs against those diseases.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.442-448
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• 2011

It's a challenging task to design a high performance modulation for satellite and space communications due to the limited power and bandwidth resource. Constant envelope modulation is an attractive scheme to be used in such cases for their needlessness of input power back-off about 2~3 dB for avoidance of nonlinear distortion induced by high power amplifier. The envelope of Feher quadrature phase shift keying (FQPSK) has a least fluctuation of 0.18 dB (quasi constant envelope) and can be further improved. This paper improves FQPSK by defining a set of new waveform functions, which changes FQPSK to be a strictly constant envelope modulation. The performance of the FQPSK adopting new waveform is justified by analysis and simulation. The study results show that the novel FQPSK is immune to the impact of HPA and outperforms conventional FQPSK on bit error rate (BER) performance. The BER performance of this novel modulation is better than that of FQPSK by more than 0.5 dB at least and 2 dB at most.