• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.1-9
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• 2023

Objective: This study identifies the difference among the heights of a chair's backrest (High, Mid, No), the biomechanical changes chair users undergo over time, and the variables that can measure musculoskeletal disorders, eventually providing information on the appropriate type of backrest. Method: Eleven healthy subjects in their 20s and 30s who had no experience with musculoskeletal disorders or surgical operations within the last 6 months participated in this study. Computer typing tasks were randomly designated and performed according to the type of chair backrest, and evaluation was performed for Flexion-Relaxation Ratio (FRR) analysis after the computer typing tasks. This study used eight infrared cameras (sampling rate: 100 Hz) and nine-channel electromyography (sampling rate: 1,000 Hz). ANOVA with repeated measures was conducted to verify the results, with the statistical significance level being α = .05. Results: Although there was no significant difference in craniovertebral angle (CVA), this study showed time and interaction effects depending on the height of the backrest (p<.05). When working without the backrest, the head-spine angle was lower compared to the chairs with backrest, based on the computer work. As for the head angle, the higher the back of the chair was, the less the head flexion and the body angle became, whereas the body flexion became less when there was a backrest. In addition, the body flexion increased over time in all types of backrests (p<.05). The muscle activity of the upper body tended to be high in the high backrest chair. On the other hand, a lower muscle activity was found with a low backrest. Conclusion: These results show that a chair is more ergonomic when the body angle is correctly set without bending and when it is supported by a low backrest. Accordingly, this study determines that the backrest affects shoulder and neck musculoskeletal disorders during typing and that medium-height backrest chairs can help prevent musculoskeletal disorders, contrary to the expectation that high-backrest chairs are preferable.

• International Journal of Control, Automation, and Systems
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• v.4 no.3
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• pp.325-332
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• 2006

The dynamic responses of human standing postural control were investigated when subjects were exposed to long-term horizontal vibration. It was hypothesized that the motion of standing posture complexity mainly occurs in the mid-sagittal plane. The motor-driven support platform was designed as a source of vibration. The AC Servo-controlled motors produced anterior/posterior (AP) motion. The platform acceleration and the trunk angular velocity were used as the input and the output of the system, respectively. A method was proposed to identify the complexity of the standing posture dynamics. That is, during AP platform motion, the subject's knee, hip and neck were tightly constrained by fixing assembly, so the lower extremity, trunk and head of the subject's body were individually immovable. Through this method, it was assumed that the ankle joint rotation mainly contributed to maintaining their body balance. Four subjects took part in this study. During the experiment, the random vibration was generated at a magnitude of $0.44m/s^2$, and the duration of each trial was 40 seconds. Measured data were estimated by the coherence function and the frequency response function for analyzing the dynamic behavior of standing control over a frequency range from 0.2 to 3 Hz. Significant coherence values were found above 0.5 Hz. The estimation of frequency response function revealed the dominant resonance frequencies between 0.60 Hz and 0.68 Hz. On the basis of our results illustrated here, the linear model of standing postural control was further concluded.

• Physical Therapy Korea
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• v.26 no.4
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• pp.1-9
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• 2019

Background: Cervical dysfunction is a common pathomechanical marker in individuals with forward head posture (FHP). To overcome the limitations of the isometric chin-tuck (ICT) exercise, dynamic neuromuscular stabilization (DNS), which emphasizes an entire spinal chain exercise, has recently shown promising clinical results. Objects: Purpose of this study was to compare the immediate effects between ICT and DNS techniques. Methods: 43 young subjects (mean age, $24.0{\pm}5.0$ years) were recruited. Group of subjects with FHP were measured under baseline, ICT, and DNS conditions. Outcome measures included sitting height, longus colli (LC) and sternocleidomastoid (SCM) muscle thickness and LC/SCM thickness ratio. One-way repeated measures ANOVA was used to compare the continuous dependent variables among FHP, ICT, and DNS conditions at p<.016. Results: Both ICT and DNS exercise conditions yielded significantly increased LC muscle thickness, LC/SCM thickness ratio and sitting height than did FHP condition (p<.0001, respectively). Sitting height was significantly greater in DNS exercise than in the ICT exercise (p<.0001). Conclusion: The present results demonstrated that sitting height was greater in the DNS exercise than in the ICT exercise, as well as both corrective postural training exercises were effective on LC/SCM muscle balance ratio when compared with the baseline FHP condition. Therefore, it is considered that DNS exercise can be the recommended exercise for people with FHP.

• Korean Journal of Acupuncture
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• v.30 no.3
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• pp.171-177
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• 2013

Objectives : The purpose of this study is to investigate the mechanism of Cosmetic Acupuncture through reinterpretation of anatomy and physiology. Methods : The causes of wrinkle increases and rapid aging of facial skin were studied and the theoretical system of Cosmetic Acupuncture treatment was analyzed through anatomy and physiology reinterpretation. Results and Conclusions : An increase in wrinkles and rapid aging of facial skin is caused by xerosis. Skin condition represents the condition of subcutaneous muscle. The reason why skin becomes easily dry is the heat produced by craniofacial part. Craniofacial part always generates lot of physiological fever because of the muscles. This physiological fever is produced from the muscles that are responsible for maintaining skull suture, controlling the movement of temporomandibular joint, maintaining head and neck posture. Controlling this fever is the crux of Cosmetic Acupuncture mechanism. These muscles correspond to Foot Taeyang meridian-muscle, Foot Soyang meridian-muscle and Foot Yangmyung meridian-muscle. Cosmetic Acupuncture is effective for preventing facial skin from aging and wrinkle increase by mechanical stimulus on facial muscles, and for controlling craniofacial part meridian-muscle system producing the heat.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.9 no.2
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• pp.5-11
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• 2003

Thoracic outlet syndrome is actually a collection of syndromes brought about by abnormal compression of the neurovascular bundle by bony, ligamentous or muscular obstacles between the cervical spine and the lower border of the axilla. First of all a syndrome is defined as a group of signs and symptoms that collectively characterize or indicate a particular disease or abnormal condition. The neurovascular bundle which can suffer compression consists of the brachial plexus plus the C8 and T1 nerve roots and the subclavian artery and vein. The brachial plexus is the network of motor and sensory nerves which innervate the arm, the hand, and the region of the shoulder girdle. The vascular component of the bundle, the subclavian artery and vein transport blood to and from the arm. the hand. the shoulder girdle and the regions of the neck and head. The bony, ligamentous, and muscular obstacles all define the cervicoaxillary canal or the thoracic outlet and its course from the base of the neck to the axilla or arm pit. Look at the scheme of this region and it all becomes more easily understood. Compression occurs when the size and shape of the thoracic outlet is altered. The outlet can be altered by exercise, trauma, pregnancy, a congenital anomaly, an exostosis, postural weakness or changes. Thoracic outlet syndrome has been described as occurring in a diverse population. It is most often the result of poor or strenuous posture but can also result from trauma or constant muscle tension in the shoulder girdle. The first step to beginning any treatment begins with a trip to the doctor. Make a list of all of the symptoms which seem to be present even if the sensations are vague. Make a note of what activities and positions produce or alleviate the symptoms and the time of day when symptoms are worst. Also, note when the symptoms first appeared. This list is important and should also include any questions one may have.

• International Journal of Quality Innovation
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• v.9 no.1
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• pp.22-40
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• 2008

Unnatural working postures usually cause musculoskeletal problems for workers in work field, especially in traditional industry. Many analysis and survey methodologies have been developed to identify unnatural postures and disorder risks in workplaces. The Ovako Working Posture Analyzing System (OWAS) and Nordic Musculoskeletal Questionnaire (NMQ) are the representative methods and applied widely. This study applied the both tools to investigate the work field of a manufacturing factory of the water heater's case. We divided the manufacturing process into nine workshops, took the pictures of working motions by DV camera and analyzed the postures on OWAS. From the OW AS results, we could identify the risks level of musculoskeletal symptoms as four Action Categories (AC). And from the comparison of OWAS and NMQ results, we could provide the suggestions to improve the working methods and environment. From the results of OWAS, we found that the operators' head/neck and back were above AC3 in some workshops. If the situation continued in long period, the operators might have the risk to get musculoskeletal symptoms. From the investigation of NMQ, we also found that the percentage of aches on neck, shoulders and lower back were higher than other parts of body. The correlation between aches and jobs was more than 75%. So we provided some suggestions to improve: work rotation and adjustment of work surface/height to fit in with Ergonomics. Then the risks of musculoskeletal symptoms would be reduced.

• Journal of Korean Neurosurgical Society
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• v.61 no.2
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• pp.277-281
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• 2018

Objective : Craniovertebral junctional anomalies constitute a technical challenge. Surgical opening of atlantoaxial joint region is a complex procedure especially in patients with nuchal deformity like basilar invagination. This region has actually very complicated anatomical and functional characteristics, including multiple joints providing extension, flexion, and wide rotation. In fact, it is also a bottleneck region where bones, neural structures, and blood vessels are located. Stabilization surgery regarding this region should consider the fact that the area exposes excessive and life-long stress due to complex movements and human posture. Therefore, all options should be considered for surgical stabilization, and they could be interchanged during the surgery, if required. Methods : A 53-year-old male patient applied to outpatients' clinic with complaints of head and neck pain persisting for a long time. Physical examination was normal except increased deep tendon reflexes. The patient was on long-term corticosteroid due to an allergic disease. Magnetic resonance imaging and computed tomography findings indicated basilar invagination and atlantoaxial dislocation.The patient underwent C0-C3-C4 (lateral mass) and additional C0-C2 (translaminar) stabilization surgery. Results : In routine practice, the sites where rods are bound to occipital plates were placed as paramedian. Instead, we inserted lateral mass screw to the sites where occipital screws were inserted on the occipital plate, thereby creating a site where extra rod could be bound.When C2 translaminar screw is inserted, screw caps remain on the median plane, which makes them difficult to bind to contralateral system. These bind directly to occipital plate without any connection from this region to the contralateral system.Advantages of this technique include easy insertion of C2 translaminar screws, presence of increased screw sizes, and exclusion of pullout forces onto the screw from neck movements. Another advantage of the technique is the median placement of the rod; i.e., thick part of the occipital bone is in alignment with axial loading. Conclusion : We believe that this technique, which could be easily performed as adjuvant to classical stabilization surgery with no need for special screw and rod, may improve distraction force in patients with low bone density.

• Journal of TMJ Balancing Medicine
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• v.13 no.sup
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• pp.27-33
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• 2023

The purpose of this study is to describe the effects of temporomandibular joint balancing therapy on a patient with a spinal accessory neuropathy. A patient reported sternocleidomastoid muscle and trapezius muscle weakness after self-massage. The patient was instructed to wear the Accurate Balancing Appliance (ABA) for at least 8 hours per day and maintain an upright posture. The patient received cervical spine manipulation on day 2, 4, and 6. The patient's progress was tracked based on the angle at which the head turned to the right from the midline when she lifted her head while lying down, as well as the muscle strength and pain in the right trapezius muscle. The patient recovered spontaneously after 7 days. The ABA and cervical spine manipulation assisted the patient in reducing fatigue and discomfort during daily activities.

• Journal of dental hygiene science
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• v.9 no.4
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• pp.413-418
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• 2009

This study was to investigate the muscoulosckeletla pain from 214 dental hygienist during treatment process in Ulsan and Kyungnam. The data collection was done from March to May in 2009 with questionnaire. The study results were as follows. In the participant's age characteristic, under 23 years old(34.1%) was majority, other participant age group were 24~26 years old(33.6%), 25~29 years old(20.6%), and over 30 years old(11.7%). Other participant characteristic were unmarried participant(86.4%), none religion(43.5%), and graduation from college(88.3%). In the participant's business characteristic, working place were dental clinic(57.5%), and dental hospital(42.5%), career was 1~2 years(42.5%) and a number of change job was once(45.1%). Salary were 1,300,000~1,490,000 won (33.6%), 1,500,000~1,990,000 won(29.9%), under 1,300,000 won(26.2%), 2,000,000~2,490,000 won(7.5%). A number of dental hygienist was over 20 person(85.9%) and the average dental hygienist was 15.6 person. A number of dentist were one person(28.5%), 2 person(22.4%), 4 person(19.2%) and the average dentist was 3.2 person. Dental hygienist's working hour was 8~9(49.5%), a large part of dental hygienist was assistance of general treatment(70.1%). Other results were 5 days/week working(60.3%), and night shift(49.1%). In an effect of musculoskeletal pain during working, neck pain was significantly influenced by body posture such as "head forward 15 degree or head round", "non balanced shoulders", "bend waist", "bend wrist", and "sit astraddle on a chair". Shoulders pain was significantly influenced by body posture such as "head forward over 15 degree", "bend waist", and "stand up straightly". Knee pain was significantly influenced by body posture such as "stand up straightly", and hip pain was influenced by "sit astraddle on chair".

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.8 no.2
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• pp.57-71
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• 2002

Cervical pain is a rapid increase that is owing to a flexion-extension whiplash injury, unappropriated posture, chronical repetition injury from abdominal position of head and neck, excessive repeating work, chronical deficiency of excercise. Because of that is bring about muscle unbalance, tightness of cervical extensor muscle, weakness of cervical deep flexor muscles, instability of cervical region and reduction of proprioceptive sensor. Recent the role of muscle is more emphasized for preservation of sine stabilization. And cognition of integrated muscular system, importance for the operation and relation is increased to maintain stability of the motor system and pertinent function. Therefore we are going to introduce the sling exercise and stabilization exercise method for advanced efficient of cervical and upper limb and for the muscle strengthening to importance cervical stabilization through neurological program as control the reaction of cervical stabilization. Sling exercise therapy(SET) concept consists of a system of diagnosis and treatment. The system of diagnosis involves testing the muscle's tolerance through progressive loading in open and close kinetic chains. The SET system contains elements such as relaxation, increasing the range of movement, traction, training the stabilizing musculature, sensory-motor exercises, training in open and close kinetic chains, dynamic training of the mobilizing musculature, cardiovascular exercise, group exercise, personal exercise at home Sensory-motor training is an essential element of the SET concept. The emphasis is on closed kinetic chain exercise on an unstable surface, there by achieving optimum stimulation of the sensory-motor apparatus.