• 제어로봇시스템학회논문지
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• 제16권7호
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• pp.688-694
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• 2010

This paper presents a gravity compensator for the manipulator of a service robot. The manipulator of a service robot is operated with low velocity for the safety reason in most cases. In this situation gravitational torques generated by the mass of links are often much greater than dynamic torques for motion. A gravity compensator can counterbalance the gravitational torques, thereby enabling to utilize relatively low power motors. In this paper the gravity compensation for the roll-pitch rotation is considered which is often used for the shoulder joints of the manipulator of a service robot or humanoid robot. A gimbals is implemented and two 1-dof gravity compensators are equipped at the base. One compensates the gravitational torque at the roll joint and another provides the compensational torque for the gimbals. Various analyses showed that the proposed compensator can counterbalance the gravitational torques of 87% at the pitch joint and 50% at the roll joint. It is verified from dynamic simulations that the proposed compensator effectively counterbalances the gravitational torques.

• 대한기계학회논문집A
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• 제33권7호
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• pp.693-699
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• 2009

This paper shows mechanical properties and behaviors of macro- and micro-structures on friction stir welded specimen with 6061-T6 aluminum alloy plate. It apparently results in defect-free weld zone jointed at welding conditions like the traverse speed of 267mm/min, tool rotation speed of 2500rpm, pin inserted depth of 4.5mm and tilting angle of $2^{\circ}$ with tool dimensions such as tool pin diameter of 5mm, shoulder diameter of 15mm and pin length of 4.5mm. The tensile stress ${\sigma}_T=228MPa$ and the yield point ${\sigma}Y=141MPa$ are obtained at the condition of traverse speed of 267mm/min and tool rotation speed of 2500rpm. With the constant rotation speed, the higher traverse speed become, the higher tensile stress and yielding point become. Vickers hardness for welding zone profile were also presented.

• 한국정밀공학회지
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• 제25권1호
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• pp.145-150
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• 2008

One of the unresolved questions in articular cartilage biomechanics is the magnitude of the dynamic modulus and tissue compressive strains under physiological loading conditions. The objective of this study was to characterize the dynamic modulus and compressive strain magnitudes of bovine articular cartilage at physiological compressive stress level and loading frequency. Four bovine calf shoulder joints (ages 2-4 months) were loaded in Instron testing system under load control, with a load amplitude up to 800 N and loading frequency of 1 Hz, resulting in peak engineering stress amplitude of ${\sim}5.8\;MPa$. The corresponding peak deformation of the articular layer reached ${\sim}27%$ of its thickness. The effective dynamic modulus determined from the slope of stress versus strain curve was ${\sim}23\;MPa$, and the phase angle difference between the applied stress and measured strain which is equivalent to the area of the hystresis loop in the stress-strain response was ${\sim}8.3^{\circ}$. These results are representative of the functional properties of articular cartilage in a physiological loading environment. This study provides novel experimental findings on the physiological strain magnitudes and dynamic modulus achieved in intact articular layers under cyclical loading conditions.

• 한국의류학회지
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• 제36권11호
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• pp.1186-1196
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• 2012

This study investigated the garments of middle-aged women undergoing menopause and their satisfaction with them. Data were collected through a survey of 288 middle-aged women and analyzed using SPSS 17.0. As a result (in terms of degree of symptoms) backache, arthralgia, muscular pain and heat sensation were indicated as significantly more outstanding in the menopause group rather than the menopausal transition group. As a countermeasure to physiological symptoms, a change of temperature (warming or cooling) was applied for backache and arthralgia as well as taking medicine for stomachaches and muscular pain. Body parts suffering from heat sensations were the face, back neck, chest center, waist and hip. Body parts suffering from arthralgia and muscular pain were the shoulder and hip joints. The most significant purchasing factor for menopausal women was the fit of outerwear and antibiosis in underwear; however, women not undergoing menopause selected comfortableness when moving as the most important factor. In terms of body shaping and thermoregulation function, the satisfaction degree in underwear was significantly different between the two groups. Menopausal women wanted functional underwear that provided functions such as thermoregulation, absorption of secretions, and antibiosis.

• Safety and Health at Work
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• 제13권3호
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• pp.315-325
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• 2022

Background: Firefighters are required to carry self-contained breathing apparatus (SCBA), which increases the risk of musculoskeletal disorders. This study assessed the newly recruited firefighters' internal forces and potential musculoskeletal disorders when carrying SCBA. The effects of SCBA strap lengths were also evaluated. Methods: Kinematic parameters of twelve male subjects running in a control condition with no SCBA equipped and three varying-strapped SCBAs were measured using 3D inertial motion capture. Subsequently, motion data and predicted ground reaction force were inputted for subject-specific musculoskeletal modeling to estimate joint and muscle forces. Results: The knee was exposed to the highest internal force when carrying SCBA, followed by the rectus femoris and hip, while the shoulder had the lowest force compared to the no-SCBA condition. Our model also revealed that adjusting SCBA straps length was an efficient strategy to influence the force that occurred at the lumbar spine, hip, and knee regions. Grey relation analysis indicated that the deviation of the center of mass, step length, and knee flexion-extension angle could be used as the predictor of musculoskeletal disorders. Conclusion: The finding suggested that the training of the newly recruits focuses on the coordinated movement of muscle and joints in the lower limb. The strap lengths around 98-105 cm were also recommended. The findings are expected to provide injury interventions to enhance the occupational health and safety of the newly recruited firefighters.

• Journal of Sport and Applied Science
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• 제5권4호
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• pp.1-8
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• 2021

Purpose: Sarcopenia is defined as a decrease in muscle mass, strength, and function with age that affects overall body function. We aimed to investigate the effect of combined training on body composition, balance, and muscle function in sarcopenia elderly. Research design, data, and methodology: Twenty-eight sarcopenia elderly (age 74.9±4.5 years) were randomly assigned to an exercise, EG (n=14), or a control, CG (n=14), group. The EG performed an intervention consisting of combined exercise training (60-75 min) for a total of 12 weeks, three times a week. The CG maintained their usual daily lifestyle during the intervention period. We measured body weight, body mass index (BMI), % body fat, free fat mass, balance ability, peak torque in shoulder, knee, and lumbar joints normalized for bodyweight in one second. Results: The EG showed improved body composition (i.e., BMI, fat-free body mass, fat mass; all p < 0.031, η² > 0.179), balance (i.e., right and left of static and dynamic balance and fast 10 m walk; all p < 0.049, η² > 0.152), and muscular function (i.e., 90°/sec and 180°/sec peak power per kg bodyweight, 90°/sec average power per kg bodyweight, 180°/sec total work, and 180°/sec endurance ratio; all p < 0.045, η² > 0.158). Conclusions: Combined exercise training improves muscle mass and strength, body composition, balance, and muscle function in sarcopenia elderly.

• 대한정형도수물리치료학회지
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• 제29권3호
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• pp.13-22
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• 2023

Background: The purpose of this study was to investigate the effects of functional massage and stretching, applied to the elbow and shoulder joints, on pain, tenderness threshold, and grip strength. Methods: A total of 29 individuals were assigned to a single site (n=15) or multiple sites (n=14). Pain measured through the visual analogue scale (VAS), tenderness threshold (TTH), and grip strength (GI) were measured before and four weeks after the intervention. Results: After four weeks of treatment, visual analogue scale significantly decreased in both groups (p<.05), and the tenderness threshold and grip strength significantly increased in both groups (p<.05). There was also a significant difference between the two groups (p<.05). Conclusion: The reduction of visual analogue scale and the increase in the tenderness threshold and grip strength were more significant in the multi-site treatment group than in the single-site treatment group.

• 근관절건강학회지
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• 제31권1호
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• pp.1-11
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• 2024

Purpose: This study aimed to evaluate the effects of an arthritis self-management program on elderly women living alone in the community. Methods: This study recruited 36 individuals, who participated in the program once a week for six weeks at two community centers. The program consisted of muscle strengthening and flexibility exercises, health education on muscles and joints, and joint dance for aerobic exercise. The data collected were analyzed using the paired t-test and Wilcoxon rank test. Results: After six weeks, participants showed significant improvements in pain (t=3.03, p=.005), difficulties in activities of daily living (t=2.77, p=.010), health-related quality of life (t=-2.63, p=.014), flexibility of right shoulder (z=-2.42, p=.015), and balance (right leg, t=-2.63, p=.036; left leg, z=-2.36, p=.018). Conclusion: The results showed that the arthritis self-management program effectively improved outcomes for elderly women living alone. Thus, this program could be incorporated into various programs for elderly people living alone.

• Clinics in Shoulder and Elbow
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• 제9권2호
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• pp.189-195
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• 2006

Purpose: To analyze the result of the accurate open reduction of acromioclavicular (AC) joint and pin fixation, coracoclavicular (CC) screw fixation without CC ligament repair for AC joint injuries. Materials and Methods: Between January 2000 and December 2003, seventeen cases with at least one year follow-up among twenty-one cases underwent operation for AC-CC ligament injuries. A transverse incision approximately 5 cm in length was made over the clavicle, and the AC joint was reduced accurately. Under the image intensifier, a cannulated screw and washer were inserted for the CC ligament. Two Steinman pins were inserted for the AC joint and the AC ligament was repaired with nonabsorbable suture. Gentle passive range of motion was begun postoperative 2 weeks. The pins were removed at $6{\sim}8$ weeks and the screw was removed at $10{\sim}12$ weeks. The results were evaluated by a distance between AC and CC joints on plain films and ASES score at last follow-up. Results: At the last follow-up, there was no limitation of motion and average ASES score was 96($86{\sim}100$ points). There was no failure showing over 5 mm difference of distance compared to opposite side on the plain films. Seven cases had the skin damages and local infection due to pin migration and three cases showed the loosening of CC screw. Conclusion: We could have satisfactory results by accurate reduction of AC joint and simple pins and screw fixation for AC-CC ligament injuries.

• Clinics in Shoulder and Elbow
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• 제11권1호
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• pp.57-61
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• 2008

흉쇄 관절의 결핵성 관절염은 매우 드문 질환으로 임상 증상이 뚜렷하지 않기 때문에 진단이 늦어지는 경우가 많다. 흉쇄 관절 부위의 점진적으로 진행하는 동통이나 종창, 미열이 있으면서 결핵의 과거력이 있는 경우에 결핵성 관절염을 의심해야 하고 혈액 검사, 방사선 검사, 조직 검사를 통한 조기 진단이 중요하다. 흉쇄 관절 결핵 관절염의 경우 1년 이상의 항결핵제 투여가 필요하며 증상의 호전이 없거나 증상이 진행되어 흉쇄 관절의 관절 파괴 소견이 보이는 경우 수술적 치료가 필요하게 되는데 수술적 치료 시 흉쇄 관절의 늑쇄골 인대의 손상을 최소화하면서 과도한 변연 절제술로 인해 흉쇄 관절의 주위의 종격동, 늑막 등의 중요 구조물이 손상되는 것을 피해야 한다. 저자들은 경험한 2예의 흉쇄 관절 결핵 관절염에서 변연 절제술로 증상의 호전을 가져온 1예와 변연 절제술 후 종격동 농양, 삼출성 늑막염 등의 합병증이 발생된 1예를 함께 보고하고자 한다.