• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.771-782
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• 2017

This paper describes the development of a wearable robot to assist ankle power for the elderly. Previously developed wearable robots have generally used motors and gears to assist muscle power during walking. However, the combination of motor and reduction gear is heavy and has limitations on the simultaneous control of stiffness and torque due to the friction of the gear reducer unlike human muscles. Therefore, in this study, Mckibben pneumatic muscle, which is lighter, safer, and more powerful than an electric motor with gear, was used to assist ankle joint. Antagonistic actuation using a pair of pneumatic muscles assisted the power of the soleus muscles and tibialis anterior muscles used for the pitching motion of the ankle joint, and the model parameters of the antagonistic actuator were experimentally derived using a muscle test platform. To recognize the wearer's walking intention, foot load and ankle torque were calculated by measuring the pressure and the center of pressure of the foot using force and linear displacement sensors, and the stiffness and the torque of the pneumatic muscle joint were then controlled by the calculated ankle torque and foot load. Finally, the performance of the developed ankle power assistive robot was experimentally verified by measuring EMG signals during walking experiments on a treadmill.

• Journal of Yeungnam Medical Science
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• v.7 no.1
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• pp.29-37
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• 1990

The effects of insulin and exercise on glucose uptake of skeletal muscle were investigated in soleus muscle isolated from low dose streptozotocin induced diabetic rats in vitro. Glucose uptake was assessed by measuring $^3H$-methylglucose uptake in vitro. Basal glucose uptake in diabetes was reduced by approximately one-third of the control value($5.6{\pm}0.73{\mu}Mol$/g/20min. in diabetes versus $8.4{\pm}0.77$ in control, P<0.01). There was also a significant decrease(P<0.01) in glucose uptake of diabetes at physiologic insulin concentration ($200{\mu}IU$/ml) by 40% ($6.1{\pm}1.20$ versus $10.0{\pm}0.81$). Furthermore, maximal insulin($20000{\mu}IU$/ml)-stimulated glucose uptake was 36% lower in diabetes as compared with control($7.3{\pm}1.29$ versus $11.4{\pm}1.29$, P<0.01). In contrast, exercise(1.0km/hr, treadmill running for 45min.) effect on glucose uptake was so dramatic in diabetes that glucose uptake at basal state was 8.4+1.09 and insulin stimulated-glucose uptake were $10.2{\pm}1.47$ and $11.9{\pm}1.64$, in 200 and $20000{\mu}IU$/ml added insulin, respectively. These results suggest that insulin insensitivity develops in skeletal muscle after 2 weeks of streptozotocin-induced diabetes, but these insensitivity was recovered significantly by single session of running exercise.

• Korean Journal of Applied Biomechanics
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• v.31 no.4
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• pp.241-248
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• 2021

Objective: The purpose of this study was to investigate the difference in muscle strength, kinematics, and kinetics between injured and non-injured sides of the leg after Achilles Tendon Rupture surgery during walking and running. Method: The subjects (n=11; age = 30.63 ± 5.69 yrs; height = 172.00 ± 4.47 cm; mass = 77.00 ± 11.34 kg; time lapse from surgery = 29.81 ± 10.27 months) who experienced Achilles Tendon Rupture (ATR) surgery participated in this study. The walking and running trials were collected using infrared cameras (Oqus 300, Qualisys, Sweden, 100 Hz) on instrumented treadmill (Bertec, U.S.A., 1,000 Hz) and analyzed by using QTM (Qualisys Track Manager Ver. 2.15; Qualisys, U.S.A). The measured data were processed using Visual 3D (C-motion Inc., U.S.A.). The cutoff frequencies were set as 6 Hz and 12 Hz for walking and running kinematics respectively, while 100 Hz was used for force plate data. Results: In ATR group, muscle strength there were no difference between affected and unaffected sides (p> .05). In kinematic analysis, subjects showed greater ROM of knee joint flexion-extension in affected side compared to that of unaffected side during walking while smaller ROM of ankle dorsi-plantar and peak knee flexion were observed during running (p< .05). In kinetic analysis, subjects showed lower knee extension moment (running at 2.2 m/s) and positive ankle plantar-flexion power (running at 2.2 m/s, 3.3 m/s) in affected side compared to that of unaffected side (p< .05). This lower positive ankle joint power during a propulsive phase of running is related to slower ankle joint velocity in affected side of the subjects (p< .05). Conclusion: This study aimed to investigate the functional evaluation of the individuals after Achilles tendon rupture surgery through biomechanical analysis during walking and running trials. Based on the findings, greater reduction in dynamic joint function (i.e. lower positive ankle joint power) was found in the affected side of the leg compared to the unaffected side during running while there were no meaningful differences in ankle muscle strength and walking biomechanics. Therefore, before returning to daily life and sports activities, biomechanical analysis using more dynamic movements such as running and jumping trials followed by current clinical evaluations would be helpful in preventing Achilles tendon re-rupture or secondary injury.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.303-309
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• 2021

This study examined the changes in the cardiopulmonary functions of stroke patients by adjusting the s heart rate during walking training. This study was conducted on 20 chronic stroke patients. The experimental group conducted walking training by varying the walking speed according to the change in heart rate on the treadmill. In contrast, the control group conducted walking training by the subjective speed of the subject. The walking training was conducted for 32 minutes, three times a week, for a total of six weeks. The changes after the intervention of the subjects were determined by measuring the VC, ERV, IRV, FVC, FEV1, and PEF. The study revealed interactions between the groups and timing in the VC, ERV, and IRV(p<.05). There were no interactions between the groups and timing in FEV1, FVC, and PEF. The main effects showed no significant differences between the groups (p>.05) but showed significant differences between periods (p<.05). These results suggest that the cardiopulmonary function was improved significantly when the training was conducted by changing the pace of the heart rate in the walking process, leading to significant changes in the cardiopulmonary function.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.417-424
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• 2018

The purpose of this study was to examine how combined exercise and acaiberry intake make effects on insulin and glycated hemoglobin of middle-aged women. The middle-aged women in their 40s and 50s were classified into three groups - group A which only had acaiberry intake, group B which both had acaiberry intake and combined exercise, and group C which only underwent the combined exercise. The combined exercise was held three times a week for 8 weeks, each for 60 minutes including warming up and cooling down. The aerobic exercise was carried out for 20 minutes with a treadmill walk with HRmax 50-60% and the resistance movement was carried out for 20 minutes with a strength of 50-60% based on 1RM. The participants were told to have the acaiberry drink before breakfast and dinner, by melting 5g of acaiberry powder to water. 2-way RGRM ANOVA was carried out to process the data for comparing each groups. In conclusion, the 8-weeks of combined exercise and acaiberry ingestion therapy did not improve the insulin and glycated hemoglobin. It is more likely to show clear changes in both elements with longer treatments and controlling the amount of ingestion and exercise intensity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.94-101
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• 2019

Most of the existing rail structures have undergone a lot of aging since a considerable period of time has passed from completion. In particular, among existing railway bridges, many of the plate girder bridges are older bridges that have lived 40 to 60 years or more. Since the treadmill is directly connected to the girder without the ballast, the running load of the vehicle is directly transmitted to the bridge. Therefore, the shock and noise applied to the bridge are larger than those of the ballast bridge, and the dynamic shock and vibration are also relatively large. Therefore, it is very urgent to develop appropriate maintenance, repair and reinforcement technology for existing steel plate bridge. In this study, the authors introduced the characteristics of embedded rail (ERS) developed for improving the performance of the existing plate girder bridge and the techniques solving the vibration and noise problems. In order to evaluate the vibration and noise reduction performance of ERS, a non-ballast plate girder bridge with 5m length of sleepers installed and a plate girder bridge with ERS were fabricated. And, then, the vibration response generated under the same excitation condition was measured and analyzed. Also, the radiated noise analysis was performed using the vibration response data obtained from the experiment as the input data of the acoustic analysis model. As a result of experiments and analyses, it was confirmed that the plate girder bridge's vibration using ERS was reduced by 15.0~18.8dB and the average noise was reduced by 7.7dB(A) more than the non-ballast bridge.

• Journal of the Korean Applied Science and Technology
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• v.36 no.3
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• pp.804-812
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• 2019

The purpose of this study was to investigate the effects of different types of exercise training on neurodegeneration and cognitive function in mice with impaired glucose tolerance (IGT). Thirty-six male C57BL/6 mice were randomly assigned to the control (CO, n = 9) and impaired glucose tolerance (IGT, n = 27) groups. The IGT group consumed 45% high fat diet for 4 weeks and received 40 mg/kg of streptozotocin twice in the lower abdomen to induce IGT. After the IGT induction period, the IGT group was subdivided into IGT + sedentary (IGT, n = 9), IGT + endurance exercise (IGTE, n = 9), and IGT + resistance exercise (IGTR, n = 9). The IGTE and IGTR groups performed treadmill and ladder climbing exercises 5 times per week for 8 weeks, respectively. Fasting glucose and glycated hemoglobin (HbA1c) levels were significantly higher in IGT group than in CO, IGTE, and IGTR groups (p < 0.05). HOMA-IR was significantly higher in IGT group than CO group (p < 0.05). Hippocampal catalase (CAT) was significantly lower in IGT group than in CO group (p < 0.05), while beta-amyloid ($A{\beta}$) was significantly higher in IGT group than in CO group (p < 0.05). Hippocampal tau was significantly higher in IGT group than in CO, IGTE, and IGTR groups (p < 0.05). The Y-maze test performance for cognitive function was significantly lower in IGT group than in CO, IGTE, and IGTR groups (p <0.05). These results suggest that IGT induces neurodegeneration and negatively affects cognitive function, while regular exercise may be effective in alleviating neurodegeneration and cognitive decline regardless of exercise type.

• Journal of Life Science
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• v.29 no.8
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• pp.837-845
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• 2019

The purpose of this study was to analyze the effects of aerobic exercise and resveratrol supplementation on mitochondrial biogenesis in skeletal muscle of high-fat diet-induced obese mice. In this study, 4-wk-old C57BL/6 male mice were divided into four groups, with 10 animals in each group: a normal diet group (NC), high-fat diet group (HC), high-fat diet group with resveratrol supplementation (HRe), and high-fat diet GROUP with exercise (HE). Aerobic exercise was performed on a treadmill for 40~60 min/d at 10~14 m/min, 0% grade, 4 d/wk for 16 wk. Resveratrol (25 mg/kg bodyweight) was administrated once a day, 4 d/wk for 16 wk. There was a significance difference in COX-IV mRNA expression in the NC group versus that in the HC group (p<0.05). The expression of the SIRT-3, PGC-1a, and COX-IV mRNA genes in the HE group increased significantly as compared with the expression of these genes in the HC and HRe groups (p<0.05). These results indicated that high- fat diet-induced obesity did not affect mitochondria biogenesis gene expression in skeletal muscle. In contrast, aerobic exercise training increased the expression of mitochondria biogenesis gene expression in skeletal muscle in high-fat diet-induced obese mice. These findings suggested that aerobic exercise but not resveratrol supplementation had a positive effect on mitochondrial biogenesis in skeletal muscle in high-fat diet-induced obese mice.

• Journal of Life Science
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• v.29 no.5
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• pp.607-613
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• 2019

The purpose of this study was to investigate the effects of either chrysin or exercise on the inflammasome and thermogenic markers in the livers of high-fat fed mice. C57BL/6 mice were randomly assigned to four groups: normal diet control (NC; n=5), high-fat diet control (HC; n=5), high-fat diet with chrysin (Hch; n=5), and high-fat diet with moderate exercise (HME; n=5). The mice were fed a high-fat diet (60% of calories from fat) or normal diet (18% of calories from fat). Chrysin was supplemented orally as 50mg/kg/day dissolved in a 0.1ml solution of dimethyl sulfoxide. The exercised mice ran on a treadmill at 12-20 m/min for 30-60 min/day, 5 times/week, for 16 weeks. After the intervention, the epididymal fat and liver weights were significantly decreased in the HME group compared with HC and Hch groups. The adipocyte size was effectively decreased in the Hch and HME groups compared with the HC group. The inflammasome markers NLRP3, $IL-1{\beta}$, and caspase1 were significantly decreased in the Hch and HME groups compared with the HC group. The thermogenic markers $PGC-1{\alpha}$ and BMP7 were significantly lower in the HC than in the NC group. However, the HME group showed an increase in the thermogenic markers. In conclusion, chrysin and moderate exercise have positive effects on obese metabolic complications induced by high-fat diets by reducing inflammasome genes. However, chrysin supplementation had no effect on thermogenic gene expression. Moderate exercise would therefore seem to be more effective in controlling obesity-induced metabolic deregulation.

• 한국체육학회지인문사회과학편
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• v.58 no.4
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• pp.447-459
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• 2019

This study was conducted to investigate the differences between emotional responses and neurotransmitters in moderate-intensity continuous exercise (MICE) and high-intensity interval exercise (HIIE) in 30 low-active women. Both groups performed a designed acute treadmill exercise and repeated the same exercise three times at intervals of one week. MICE performed a 25-minute continuous exercise at 90% VT(ventilation threshold) after a 5-minute warm-up session at 50% VT and then cooled down for 5 minutes at 50% VT level. The HIIE was repeated 6 times for 2 minutes at 115% VT level, and the intermediate active recovery was repeated 4 times for 2 minutes at 85% VT level. The results of the statistical analysis are as follows. MICE was showed positive effect for feeling scale and PACES after exercise in the first experiment, but negative effect in the third experiment. Conversely, HIIE was showed negative effect for feeling scale and PACES after exercise in the first experiment, but positive effect in the third experiment. Neurotransmitters were significantly increased in all three groups after 10 minutes of exercise compared to before exercise. In summary, HIIE exercise may be a strategy to increase exercise compliance for low-active women.