• Journal of Life Science
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• v.20 no.4
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• pp.549-554
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• 2010

Increased external rotation and decreased internal rotation have been noted to occur progressively in the throwing shoulders of baseball pitchers. The purpose of this study was to provide descriptive data for terminal range eccentric antagonist/concentric agonist shoulder muscle strength in collegiate baseball pitchers with humeral head retroversion diagnosed through MRI. The dominant and non-dominant shoulders of 9 asymptomatic baseball pitchers were tested through a range of 20 degrees of external rotation to 90 degrees of internal rotation using the Biodex system 3 isokinetic dynamometer at speeds of $90^{\circ}/s$ and $180^{\circ}/s$. Differences between the dominant and non-dominant shoulders were assessed using the paired samples t-test. Total range of motion, measured at $90^{\circ}$ of glenohumeral abduction, was $180.1^{\circ}$ for dominant shoulders and $183.7^{\circ}$ for non-dominant shoulders. Humeral head retroversion measured $47.6{\pm}6.1^{\circ}$ in dominant and $37.8{\pm}5.3^{\circ}$ in non-dominant extremities. The mean internal rotator concentric contraction (IR-Con) showed a significant difference compared to $31.5{\pm}5.1$ (Nm) in dominant and $38.7{\pm}5.2$ (Nm) in non-dominant shoulders at $180^{\circ}/s$ (p<0.05). The mean external rotator eccentric contraction (ER-Ecc) showed a significant difference compared to $20.3{\pm}4.7$ (Nm) in dominant and $25.1{\pm}3.7$ (Nm) in non-dominant shoulders at $90^{\circ}/s$ (p<0.05). There is a pattern of increased external rotation and decreased internal rotation in the dominant extremity that significantly correlates with an increase in humeral retroversion.

• Journal of the Ergonomics Society of Korea
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• v.25 no.2
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• pp.147-154
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• 2006

This study was conducted to evaluate the effect intentional contraction of abdominal muscles during lifting above shoulder on the muscles activities of the lower trunk and on the degree of lumbar extension. Fifteen healthy adult males were selected as test subjects. A 5kg weight was raised to the shoulder level, 20cm, and 40cm above the shoulder level. EMG activities of all muscles except the rectus abdominis were significantly greater when subjects were asked to contract their abdominal muscles intentionally during lifting(p<0.05). Degree of lumbar extension also significantly decreased with intentional abdominal contraction during the lifting. Also, degree of lumbar extension significantly increased with increase in lifting height(p<0.05). The results of this study show that intentional contraction of abdominal muscles during lifting above shoulder increases the EMG activities of external abdominis oblique, internal abdominis oblique, and erector spinae.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.4
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• pp.303-314
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• 2004

This study is intended to investigate the geotechnical behavior of jointed mass on tunnel excavation experimentally. Laboratory test were conducted in various conditions of distance from joint to tunnel and in-situ stress ratio ($K_0$). In case, the ground around the tunnel that has the joint angle $90^{\circ}$ generate the greatest influence in crown and far shoulder from joint. If the in-situ stress ratio is low, tangential stress of side wall that is opposite side of the joint is increased more than in crown. Otherwise in case, joint angle $45^{\circ}$, the generated compress stress is found out that left side of the tunnel of near the joint has influence on stability of the tunnel about 3 times than non-jointed rock.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.1
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• pp.13-20
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• 2021

Background: The serratus anterior and upper trapezius muscles act synergistically to allow for an appropriate scapulothoracic rhythm. However, a decrease in serratus anterior activation causes the upper trapezius to become overactivated, resulting in dysfunction. This study compared serratus anterior and upper trapezius muscle activity according to sling angle and compared serratus anterior strength between healthy adults and patients with shoulder instability. Methods: Twenty participants (10 healthy adults and 10 patients with shoulder instability) were included in this study. The participants had their arms extended at sling angles of 30°, 60°, and 90° in reach forward with shoulder flexion using goniometer. Serratus anterior strength was measured three times while the participants were supine. The outcome measures were surface electromyography amplitude of the upper trapezius and serratus anterior and serratus anterior strength. Results: The Wilcoxon signed-rank test indicated that the upper trapezius was significantly different between healthy group and shoulder instability group at a sling angle of 60°, and both the upper trapezius and serratus anterior exhibited significant differences at 90°. Moreover, a significant difference was noted in the muscle strength of the serratus anterior. Conclusion: Our results provide novel and promising clinical evidence that patients with shoulder instability have decreased serratus anterior activation and upper trapezius overactivation, resulting in muscle imbalance. In addition, there was a significant difference between the healthy group and shoulder instability group in the serratus anterior muscle strength

• Progress in Medical Physics
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• v.21 no.1
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• pp.86-92
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• 2010

The purpose of this study was to measure curvature contour skin dose using radiochromic film and TLD for a conventional open field. We also attempted to quantify the degradation of skin sparing associated with use of immobilization devices for high energy photon beams and to calculate the skin dose with a help of Monte Carlo (MC) simulation. To simulate head-and-neck and shoulder treatment, a cylindrical solid water phantom 11 cm in diameter was irradiated with 6 MV x-rays using $40{\times}40\;cm^2$ field at 100 cm source axis distance (SAD) to the center of the phantom. Aquaplastic mesh mask was placed on the surface of the cylindrical phantom that mimicked relevant clinical situations. The skin dose profile was obtained by taking measurements from $0^{\circ}$ to $360^{\circ}$ around the circumference of the cylindrical phantom. The skin doses obtained from radiochromic film were found to be 47% of the maximum dose of $D_{max}$ at the $0^{\circ}$ beam entry position and 61% at the $90^{\circ}$ oblique beam position without the mask. Using the mask (1.5 mm), the skin dose received was 59% at $0^{\circ}$ incidence and 78% at $80^{\circ}$ incidence. Skin dose results were also gathered using thin thermoluminescent dosimeters (TLD). With the mask, the skin dose was 66% at $0^{\circ}$ incidence and 80% at $80^{\circ}$ incidence. This method with the mask revealed the similar pattern as film measurement. For the treatments of the head-and-neck and shoulder regions in which immobilization mask was used, skin doses at around tangential angle were nearly the same as the prescription dose. When a sloping skin contour is encountered, skin doses may be abated using thinner and more perforated immoblization devices which should still maintain immoblization.

• Journal of the Korean Society of Radiology
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• v.9 no.6
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• pp.331-335
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• 2015

Consideration of Glenohumeral joint's image with the Changed Body angle of the Glenohumeral joint's Oblique Position in Erect Position. Glenohumeral joint's of Grashey method is a shoulder oblique method available to view the shoulder joint. Grashey method projects AP view of the Glenohumeral joint's so that the Humerus head's subluxation or joint degeneration can be easily visualized. However in this view, the patients, erect position, have to keep their body obliquely. Oblique position is will be needed to get the good quality Glenohumeral joint's view. Therefore, we thought of examining a method which shows the Glenohumeral joint's well by angling the patient one side upward in erect position. For this study, total 20 subject with no history of neurological or psychiatric illness, were recruited for examinations. They consisted of 13 mails and 7 femails, Statistic group analysis was performed with ANOVA test. Score of the evaluation of the expects were $30^{\circ}$ at $0.40{\pm}0.499$, $35^{\circ}$ at $1.34{\pm}0.657$, $40^{\circ}$ at $1.84{\pm}0.573$, $45^{\circ}$ at $0.76{\pm}0.649$, and they were significant(P<0.05). The degree of $40^{\circ}$ views were shown to yield good quality shoulder oblique images.

• Archives of design research
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• v.12 no.3
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• pp.73-80
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• 1999

Many domestic users complain about severe pain to the waist, neck, and shoulder as well as work performance because the domestic chair design was developed with western anthropometry dimension and design criteria. Ergonomic design standards are needed for office chair design to reduce stress and poor physical posture for various user body types. In this study, we have suggested design dimensions recommended from previous studies and Korean anthropometry data. We also have reviewed users' preference dimension through measured subjects and analyzed differences between users' preference dimension and the previous design criteria to verify physical appropriateness. We evaluated general office chairs and adjustable chairs which can adjust to fit each person. we also analyzed how each design dimension was reached and affected the human body by evaluation of physical discomfort and comfort. We have found seat height is very important in a workstation. If the seat height is high, it effects the thigh. If width, height, and angle of the backrest are wrong, fatigue to the shoulder, neck, and waist, etc.. As a result of this experiment, we suggested that the height of a seat for Koreans be 425mm for the fixed type and 365-484mm for the adjustable type. Also other design recommendations were suggested in the thesis. In conclusion, our research will be very important in the database because it provides adjustable ranges to fit user's body types in the various design fields.

• The Journal of the Korea Contents Association
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• v.13 no.2
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• pp.348-358
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• 2013

This study aimed to investigate the effect of a lap board that was developed to prevent musculoskeletal disorders caused by the use of a computer mouse. Study participants were 10 college students in their 20s who did not have any musculoskeletal symptoms. We analyzed the difference in upper limb movements, electromyographic activity, task performance, and subjective discomfort between 2 conditions: use of a mouse with the lap board and use of a mouse placed on a desk. Results of behavior analysis showed that there was a significant difference between the 2 conditions in terms of the average angle of shoulder flexion, shoulder internal rotation, and forearm pronation(p< 0.05). However, electromyographic activity, task performance, and subjective discomfort showed no significant differences between the 2 conditions. When subjects used the mouse with the lap board, their upper extremity was located much closer to the torso than when they used the mouse placed on the desk. Six of 10 participating students preferred the lap board. We expect that advanced research on prevention of musculoskeletal disorders due to the use of the computer mouse will be conducted in the near future.

• Physical Therapy Korea
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• v.26 no.3
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• pp.1-10
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• 2019

Background: Winged scapular (WS) causes muscle imbalance with abnormal patterns when moving the arm. In particular, the over-activation of the upper trapezius (UT) and decrease in activity of the lower trapezius (LT) and serratus anterior (SA) produce abnormal scapulohumeral rhythm. Therefore, the SA requires special attention in all shoulder rehabilitation programs. In fact, many previous studies have been devoted to the SA muscle strength training needed for WS correction. Objects: The purpose of this study was to investigate the effect of shoulder girdle muscle and ratio according to the angle of shoulder abduction and external weight in supine position. Methods: Twenty three WS patients participated in this experiment. They performed scapular protraction exercise in supine position with the weights of 0 kg, 1 kg, 1.5 kg, and 2 kg at shoulder abduction angles of $0^{\circ}$, $30^{\circ}$, $60^{\circ}$, and $90^{\circ}$. The angle and weight applications were randomized. Surface electromyography (EMG) was used to collect the EMG data of the SA, pectoralis major (PM), and UT during the exercise. The ratio of PM/SA and UT/SA was confirmed. Two-way repeated analyses of variance were used to determine the statistical significance of SA, PM, and UT and the ratios of PM/SA and UT/SA. Results: There was a significant difference in SA according to angle (p<.05). Significant differences were also identified depending on the angle and weight (p<.05). The angle of abduction at $0^{\circ}$, $30^{\circ}$ and weight of 2 kg showed the highest SA activity. However, there was no significant difference between PM and UT (p>.05). There was a significant difference between PM/SA and UT/SA in ratio of muscle activity according to angle (p<.05). Significant differences were found at PM/SA angles of $30^{\circ}$, $60^{\circ}$ and $90^{\circ}$ (p<.05). For UT/SA, significant difference was only observed at $90^{\circ}$ (p<.05). Conclusion: Based on the results of this study, in order to strengthen the SA, it was found to be most effective to use 1 and 1.5 kg weights with abduction angles of $0^{\circ}$ and $30^{\circ}$ at shoulder protraction in supine position.

• Journal of the Korean GEO-environmental Society
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• v.9 no.7
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• pp.45-51
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• 2008

Triaxial compression tests on anisotropic rock specimens are carried out to investigate the failure strength characteristic of anisotropic rocks. The test core specimens were obtained in Daegu region. Test specimens are rock cores with the 7 different angles of bedding plane. The applied confining pressures were 5, 10, 20, 30, 40 MPa, and the rate of displacement was adopted 0.1%/min to fail the specimen within 5-15 min. The results were analyzed by using the failure criteria for anisotropic rocks proposed by Hoek & Brown (1980) and Jaeger (1960). The results of this study are summerised as follows: The results of inherent anisotropy show the shoulder type of anisotropy, and the effect of anisotropy is reduced as the confining pressure increases. The compressive strength of anisotropic rock shows the highest value at the ${\beta}$ (the angle of bedding plane) = $0^{\circ}$ and $90^{\circ}$ and the lowest value at $30^{\circ}$. The Hoek & Brown failure criterion for anisotropic rocks gives a relatively good agreement with the measured strength in all the range of ${\beta}$ angles, but the theory of Jaeger shows a reasonable agreement only in the range of ${\beta}=15^{\circ}$ and $45^{\circ}$.