• Journal of the Ergonomics Society of Korea
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• v.22 no.1
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• pp.57-67
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• 2003

The resonance behaviour needs be understood to identify the mechanisms responsible for the dynamic characteristics of human body, to allow for the non-linearity when predicting the influence of seating dynamics. and to predict the adverse effects caused by various magnitudes of vibration. However, there are currently no known studies on the effect of vibration magnitude on the transmissibility to thoracic or lumbar spine of the seated person. despite low back pain(LBP) being the most common ailment associated with whole-body vibration. The objective of this paper is to develop a proper mathematical human model for LBP and musculoskeletal injury of the crew in a maritime vehicle. In this study, 7 degree-of-freedom including 2 non-rigid mass representing wobbling visceral and intestine mass, is proposed. Also. when compared with previously published experimental results, the model response was found to be well-matching. When exposed to various of vertical vibration, the human model shows appreciable non-linearity in its biodynamic responses. The relationships of resonance for LBP and musculoskeletal injury during whole-body vibration are also explained.

• Journal of Korean Medical classics
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• v.28 no.1
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• pp.35-53
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• 2015

Objectives : In order to find how reference books of Yi Xue Ru Men reflect the classification and criterion for low back pain(LBP). Methods : From reference books of Yi Xue Ru Men, select the texts on classification and criterion for LBP. Results : According to the causes of LBP, Chao Yuan Fang(巢元方) in Sui Dynasty assorted to 5 types of LBP at the very first. Chen Wu Ze(陳無擇) in Song Dynasty made 7 divisions by external, internal, and non-external, non-internal causes. According to the pulse of LBP, Yan Yong He(嚴用和) first categorized 4 groups, Zhu Zhen Heng(朱震亨) added another 4 groups. Aside from this standard, Zhu(朱震亨) adopted the cause standard. Depending on Yunqi(運氣), Lou Ying(樓英) classified 5 types. But his classification had been not adopted by any TCM books. According to symptom of 6 varieties(六變), Zhang Jie Bin(張介賓) assorted external(表), internal(裏), deficiency(虛), sufficiency(實), cold(寒) and heat(熱), add 2 groups besides them. But his categorization did not reflect Yi Xue Ru Men. Li Chan(李梴), the author of this book chose causes and pulse classification standards that Zhu Zhen Heng had adopt. Conclusions : In the side of classification and criterion for LBP, Li Chan first divided 2 group, external and internal injury. After it he subdivided both groups to 10 subgroup. His classification is similar to Chen(陳無擇)'s, but actually followed the classification for external and internal injury that was invented by Li Dong Yuan(李東垣).

• Journal of Preventive Medicine and Public Health
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• v.27 no.2 s.46
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• pp.299-312
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• 1994

This survey was performed to obtain the basic information for the prevention and management of occupational low back injury (LBI). The subjects of this survey were 952 workers (male, 892 ; female, 60) who had taken occupational LBI in some industries of Pusan area from January 1 to December 31, 1991. Observation period was 2.6 years from the beginning to the end of medical treatment. The obtained results were summarized as follows ; 1. The proportion of LBI workers was 15.9% of the workers who had taken any occpational injuries and 0.32% of all workers in this surveyed area. 2. 8.0% of the workers had taken LBI on the 1st day of employment and 55.2% of the workers were within one year, 91.4% of the workers were within 10 years according to cumulative frequency distribution. 3. Handling of heavy objects was the most common cause of LBI (32.0%) and fall down (26.9%) and slip down (16.3%) were the next in order. 4. The most common causes of both lumbar sprain and HNP were handling of heavy objects and that of lumbar fracture was fall down. 5. The mean duration for medical treatment of LBI workers was 143 days. 6. The total direct compensation cost for LBI workers was 6,736 million Won and the proportion of medical, resting, disability compensation costs were 25.0%, 37.0%, 38.0 % respectively. 7. The percentages of retreated workers and disabled workers were 11.9% (113 persons) and 22.9% (218 persons) of total LBI workers respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.182-194
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• 1999

Occupant injury in rear end impact is rapidly becoming one of the most aggravating traffic safety problems with high human suffering and societal costs. Although rear end impact occurs at relatively low speed , it may cause permanent disability due to neck injuries resulting from an abrupt moment, shear force , and tension/compression force at the occipital condyles. The analysis is performed for a combined occupant-eat model response, using the SAFE(Safety Analysis for occupant crash Environment) computer program. The computational results are verified by those from sled tests. A parameter study is conducted for many physical and mechanical properties. Seat design has been performed based on the design of experiment process with respect to five parameters; seat-back upholstery stiffness, torsional stiffness of the seat-back. An orthogonal array is selected from the parameter study. A good design has been found from the analysis results based on the orthogonal array. The results show that reductions of stiffness in seat-back upholstery and joint are the most effective for preventing neck injuries.

• Journal of Korean Physical Therapy Science
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• v.29 no.4
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• pp.75-85
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• 2022

Background: The purpose of this study was to investigate the effect of intensively complex physical therapy program on pain, range of motion (ROM) and muscle function in traumatic low back injury by industrial accident. Design: Prospective study Methods: Eight patients with traumatic low back injury by industrial accident participated in this study. They were treated the intensively complex physical therapy program including daily 60 minutes therapist supervised physical therapy at 5 times a week and 30 minutes manual therapy at 5 times a week in 12 weeks. Evaluation was performed before the commencement of the training and again 4, 8 and 12 weeks. There were measured Numerical Rating Scale (NRS) for evaluating pain, ROM of trunk, and isometric muscle strength of trunk, core muscle endurance, neuromuscular control ability for evaluating muscle function. Results: NRS was significantly improved according to time (p<0.05). ROM of extension and rotation, isometric muscle strength of trunk and hip, core muscle endurance and neuromuscular control ability were significantly improved according to time (p<0.05). Conclusion: We could confirm the superiority effect of intensively complex physical therapy program on pain, ROM of trunk and muscle function in traumatic low back pain with industrial accident.

• Journal of Auto-vehicle Safety Association
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• v.4 no.2
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• pp.37-43
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• 2012

The purpose of this research is to obtain and analyze dynamic responses from human volunteers for the development of the human-like mechanical or mathematical model for Korean males in automotive rear collisions. This paper focused on the introduction to a low-speed rear impact sled test involving Korean male subjects, and the accumulation of the motion of head and neck. A total of 50 dynamic rear impact sled tests were performed with 50 human volunteers, who are 30-50 year-old males. Each subject can be involved in only one case to prevent any injury in which he was exposed to the impulse that was equivalent to a low-speed rear-end collision of cars at 5-8 km/h for change of velocity, so called, ${\Delta}V$. All subjects were examined by an orthopedist to qualify for the test through the medical check-up of their necks and low backs prior to the test. The impact device is the pendulum type, tuned to simulate the crash pulse of a real vehicle. All motions and impulses were captured and measured by motion capture systems and pressure sensors on the seat. Dynamic responses of head and T1 were analyzed in two cases(5 km/h, 8 km/h) to compare with the results in the previous studies. After the experiments, human subjects were examined to check up any change in the post medical analysis. As a result, there was no change in MRI and no injury reported. Six subjects experienced a minor stiffness on their back for no more than 2 days and got back to normal without any medical treatment.

• Journal of the Korean Society of Physical Medicine
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• v.6 no.3
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• pp.287-292
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• 2011

Purpose :The present study invesigated the effect of changes in transversus abdominis thickness using ultrasonography during a hip adductor contraction. Methods : This study was carred out in a volunteer sample of adults (N=30) without a history of low back pain or injury. In standing position, muscle thickness measurements of transversus abdominis(TrA) were measured using ultrasonography at rest and during a hip adducor contraction. Results : TrA thickness were influenced a hip adductor during a voluntary contraction in people without LBP. TrA showed significantly greater thickness changes on a hip adductor contraction.(p=0.000) Conclusion : The results from this study showed that the hip adductor contraction improves the ability to increase change in TrA thickness. These results can be a good evidence to prevent low back pain due to hip adductor weakness or genu varum deformity of knee osteoarthritis.

• Proceedings of the ESK Conference
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• 1997.10a
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• pp.160-167
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• 1997

The statistics of work related Low Back Pains(LBPs) in Korea and outside the countires have erviewed. Despite improved working enviroment with increased automation in industry, the LBPs hve been gradually increased and the workers compensation of such injuries has increased drama- tically. An epidemiological study indicated tha tthe LBPs is te major cause of injury, lost time and medical costs in many industrial workplace especially, a high occurrence rate of LBPs among construction and manufacturing workers. The objective of this study is to investigate problems involved with LBPs in Korea and outside the country for identifying its possible causal factors and characteristics. This study will thus contribute as a basic reference to the industries and ergonomic practitioners for preventing and managing LBPs.

• Journal of Acupuncture Research
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• v.40 no.3
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• pp.188-200
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• 2023

Laryngopharyngeal reflux (LPR) disease is a condition in which the stomach contents return to the larynx and pharynx via the esophagus, causing mucosal injury. While conventional treatments, such as proton pump inhibitors, have limitations, acupuncture has been shown to reduce LPR symptoms. However, its effectiveness has not been systematically assessed. This study aimed to systematically evaluate the effectiveness of acupuncture in treating LPR. We review 10 electronic databases with a consistent search strategy, and 2 independent reviewers screened the articles based on the inclusion and exclusion criteria. This study selected and analyzed 7 randomized controlled trials after the screening to assess primary outcomes, including reflux symptom index and reflux finding score, and secondary outcomes, including upper and lower esophageal sphincter pressure. The results revealed the statistically significant effectiveness of acupuncture in combination with conventional treatment in reducing LPR symptoms compared with conventional treatment alone. The most commonly used acupuncture points were CV22, ST36, and LR3. However, the meta-analysis demonstrated low reliability, as assessed using the GRADE Tool. Further research is needed to improve the evidence and draw clear conclusions regarding the clinical use of acupuncture for treating LPR.

• Safety and Health at Work
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• v.7 no.1
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• pp.49-54
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• 2016

Background: Prolonged sitting leads to low back discomfort and lumbopelvic muscle fatigue. This study examined the characteristics of body perceived discomfort and trunk muscle fatigue during 1 hour of sitting in three postures in office workers. Methods: Thirty workers sat for 1 hour in one of three sitting postures (i.e., upright, slumped, and forward leaning postures). Body discomfort was assessed using the Body Perceived Discomfort scale at the beginning and after 1 hour of sitting. Electromyographic (EMG) signals were recorded from superficial lumbar multifidus, iliocostalis lumborum pars thoracis, internal oblique (IO)/transversus abdominis (TrA), and rectus abdominis muscles during 1 hour of sitting. The median frequency (MDF) of the EMG power spectrum was calculated. Results: Regardless of the sitting posture, the Body Perceived Discomfort scores in the neck, shoulder, upper back, low back, and buttock significantly increased after 1 hour of sitting compared with baseline values ($t_{(9)}=-11.97$ to -2.69, p < 0.05). The MDF value of the EMG signal of rectus abdominis, iliocostalis lumborum pars thoracis, and multifidus muscles was unchanged over time in all three sitting postures. Only the right and left IO/TrA in the slumped sitting posture was significantly associated with decreased MDF over time (p = 0.019 to 0.041). Conclusion: Prolonged sitting led to increased body discomfort in the neck, shoulder, upper back, low back, and buttock. No sign of trunk muscle fatigue was detected over 1 hour of sitting in the upright and forward leaning postures. Prolonged slumped sitting may relate to IO/TrA muscle fatigue, which may compromise the stability of the spine, making it susceptible to injury.