• 한국운동역학회지
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• 제24권4호
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• pp.399-415
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• 2014

The aim of this study was to investigate the effect of resistance training with and without whole-body vibration(WBV) on the biomechanical properties of the plantarflexor in the elderly women (>60 yrs., n=35). Thirty-five volunteers were randomly assigned to a resistance training with WBV group (RVT, n=14), a resistance training without WBV (RT, n=11), and a non-training control group (CON, n=10). The RVT and the RT groups participated in the training sessions three times a week for 8 weeks, followed by a 4-week detraining period. The CON group was instructed to refrain from any type of resistance training. To assess strength and activation of the plantarflexor muscles, maximum isometric ankle plantarflexion torque and muscle activation of the triceps surae muscles were measured using dynamometry, twitch interpolation technique and electromyography at four different ankle joint angles. Also, the lower extremity function was assessed by vertical jumping. The measurements were performed prior to, 2 and 8 weeks after the training and after a 4-week detraining period. Following the 8-week training sessions, an increase in the isometric plantarflexion strength was found to be greater for the RVT compared with the RT group (p<.05). Muscle inhibition was significantly decreased after training than before training only for the RVT (p<.05). Following the detraining period, a decrease in isometric plantarflexors strength and a increases in muscle inhibition were significantly less in the RVT compared with the RT group. In conclusion, the exercise with WBV is a feasible training modality for the elderly and seems to have a boosting effect when used with conventional resistance training.

• 한국운동역학회지
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• 제25권3호
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• pp.343-351
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• 2015

Objective : The purpose of this study was to investigate the effects in the muscle function following 8-week dead-lift training with Whole-body Vibration(WBV) in rehabilitation for sports players. Method : Twenty young sports players. Each subjects were randomly assigned to a resistance training with Whole-body vibration group(TG, n=10), a resistance training without Whole-body vibration group(CG, N=10). The measurements which physical fitness test and joint torque test were performed before the randomization and after the 4-week and 8-week. The WBV group performed the dynamic Dead-lift exercise on a vibration platform during one minute. The CG group performed the equal training without vibration. The WBV and CON group repeated 5 set and trained two times weekly for 8-weeks. Paired t-test was used to test for differences between the groups at baseline and after 4-weeks and 8-Weeks. And independent t-test was used to test for differences between the groups at TG and CG. All analyses were executed using SPSS software 18.0. The level of significance was set at p<.050. Results : Following the 8-Weeks training sessions, an increase in the back-muscle strength was found to be greater for the TG compared with the CG group(p<.05). Muscle endurance was significantly decreased after training than before training only for the CG(p<.05). Isometric Hip/Lumber Extension/Flextion measurement was found to be significantly greater for the TG compared with the CG group(p<.05). The finding indicates that WBV effects as an efficient training stimulus to enhance muscle function by facilitating neural control trail. Following muscle activation in motor unit synchronization of the co-contraction of the muscles. Conclusion : The results imply that the WBV training may have enhanced muscle function in rehabilitation for sports players.

• 대한기계학회논문집A
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• 제34권8호
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• pp.1129-1136
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• 2010

체결클러치에 부착된 댐퍼스프링은 유체커플링에서 직결로 변환될 때 발생하는 엔진 토크의 진동을 흡수하는 역할을 한다. 본 연구에서는 체결클러치의 성능을 좌우하는 압축스프링 및 지지 판 구조물의 최적설계를 통해서 새로운 설계형상을 제안하였다. 체결클러치와 연결된 엔진, 변속기, 구동축 및 휠, 차체질량 등 주요 부품들을 다 포함하는 다물체 동역학모델을 구성하여 공진 회피에 필요한 스프링상수를 계산하였다. 또한 어닐링 모사법에 의한 스프링 최적설계코드를 개발한 후 스프링상수, 최대충격토크, 수축각도, 스프링개수, 피로강도 등을 입력하여 압축 스프링의 사양을 최적화하였다. 이들 스프링을 지지하는 3 가지의 판에 대해서 컴플라이언스를 최소화하고 체적비를 0.3 이하로 하는 위상최적화를 수행하여 새로운 형상을 제안하였다.

• 제어로봇시스템학회논문지
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• 제14권10호
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• pp.1029-1037
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• 2008

When a humanoid robot pushes an object with its force, it is essential to adequately control its posture so as to maximize the surplus torque far all joints. For such purpose, this study proposes a method to find an optimal posture of a humanoid robot using a genetic algorithm in such a way that the surplus torque for all joints is maximized. In this study, pushing motion of an 18-DOF humanoid robot is considered. When the robot takes a cooperative motion to push an object, the palms and soles are assumed to be fixed at the object and ground respectively, and are subjected to sense the reaction force from the object and the ground. Then, the torques for all joints are calculated and reflected to fitness function of the genetic algorithm. To verify the effectiveness of the proposed method, a number of simulations with different fitness functions are carried out. The simulation result shows that the proposed method can be adopted to find optimized posture in cooperative motion of a humanoid robot.

• 대한의용생체공학회:의공학회지
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• 제30권3호
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• pp.221-225
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• 2009

The purpose of this study was to investigate the biomechanical effects of an application of whole body vibration during strengthening exercise. Every participant performed four weeks exercise program using general leg-press versus vibrating leg-press. Participants did legpress exercise three sets of 25 repetitions with the load of 25 percent of 1RM during first week, three sets of 20 repetitions with 40 percent of 1RM during second week, three sets of 15 repetitions with 60 percents of 1RM during third week, and three sets of 15 repetitions with 80 percent of 1RM during last fourth week. The vibration(25Hz, 5mm) was applied only to the vibration exercise group. A three dimensional virtual lower extremity model for one of subject and virtual leg-press model were generated. The knee extensor muscle forces were analyzed using the virtual model and the knee joint torque(maximum extension torque) was measured using an isokinetic device. Calculated muscle forces were smaller in vibrating leg-press exercise than in general leg-press exercise. An increase of the maximum knee extension joint torque was 2.14 times larger approximately after the four week vibration leg-press exercise program was performed.

• 한국정밀공학회지
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• 제29권9호
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• pp.1026-1034
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• 2012

The purpose of this study was to verify the validation of effect on improvement of muscle strength unbalance according to exercise load deviation during rowing exercise. We performed evaluation of muscular activity and joint torque before the test. We recruited twenty subjects who one side's muscle strength is bigger in more 20% than other side. Subjects divided two groups. One is dominant left side and the other was dominant right side. Subjects performed rowing exercise in electric load deviation rowing equipment (Robo.gym, Humonic Co., Ltd., Daegu, Korea). Exercise performed four sets a day including 25 times a set, and three days a week. Measurements consist of evaluation of muscular activity and joint torque. Exercise load deviation adapted that different value of muscle strength in both arms multiplied 1RM% and added 1RM 50%. The results in adapted load deviation showed that the differences of maximal peak torque in 22.75% were getting increase significantly during exercise in 5.72%. This interpreted that rowing exercise with loading deviation types could provide muscle strength and muscular endurance exercise in same time for balance. Our study found out that loading deviation could provide muscle strength and muscular endurance exercise for improving muscle unbalance.

• 드라이브 ㆍ 컨트롤
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• 제17권1호
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• pp.44-50
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• 2020

For the requirement of accurate tracking control and the safety of physical human-robot interaction, torque control is basically desirable for humanoid robots. Because of the complexity of humanoid robot dynamics, the TDC (time-delay control) is practical because it does not require a dynamic model. However, there occurs a considerable error due to discontinuous non-linearities. To solve this problem, the TDC-FLC (fuzzy logic compensator) is applied to humanoid robots. The applied controller contains three factors: a TDE (time-delay estimation) factor, a desired error dynamic factor, and FLC to suppress the TDE error. The TDC-FLC is easy to execute because it does not require complicated humanoid dynamic calculations and the heuristic fuzzy control rules are intuitive. TDC-FLC is implemented on the whole body of a humanoid, not on biped legs even though it is performed by a virtual humanoid robot. The simulation results show the validity of the TDC-FLC for humanoid robots.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.661-666
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• 2004

The purpose of this study is to measure the rotational vibration, radial vibration, and axial vibration for the helical gear with the wide face width relative to the whole depth. For this purpose, the experimental apparatus is designed and manufactured. The gear vibration of each direction is measured by the accelerometers attached at the gear body. As a result, meshing frequency and second harmonic component are greatly contributed to the gear vibration. As the rotational speed is increased, meshing frequency component has the more significant peak than the second harmonic one. However, the doubled torque decreases the vibration magnitude on the contrary and changes order of the vibration magnitude in each direction.

• 로봇학회논문지
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• 제11권3호
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• pp.183-192
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• 2016

Generating motion of center of mass for biped robots is a challenging issue since biped robots can easily lose balance due to limited contact area between foot and ground. In this paper, we propose force control method to generate high-speed motion of the center of mass for horizontal direction without losing balancing condition. Contact consistent multi-body dynamics of the robot is used to calculate force for horizontal direction of the center of mass considering balance. The calculated force is applied for acceleration or deceleration of the center of mass to generate high speed motion. The linear inverted pendulum model is used to estimate motion of the center of mass and the estimated motion is used to select either maximum or minimum force to stop at goal position. The proposed method is verified by experiments using 12-DOF torque controlled human sized legged robot.

• 재활복지공학회논문지
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• 제7권1호
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• pp.1-11
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• 2013

본 연구에서는 실내용 승마운동기를 이용하여 승마운동이 젊은 성인남녀의 기초체력, 유연성 및 근기능 증진에 미치는 효과를 정량적으로 평가하고자 하였다. 피험자들은 신체 건강한 20대 남성 10명과 여성 10명을 대상으로 실시하였다. 운동은 방향별 15분씩, 총 45분을 수행하였으며 매주 3일씩 총 4주간 진행하였다. 또한 증진효과를 알아보기 위하여 피험자들에 대한 기초체력, 유연성 및 근기능 평가를 실시하였다. 실험결과, 운동 4주 후 피험자들의 기초체력, 유연성 및 근기능 능력이 모두 유의하게 증가하는 경향을 나타냈다. 이는 승마운동 시 3차원적이며 지속적인 움직임이 복부와 요추의 길항근에 원심성 운동효과를 유도하였으며 또한 유연한 움직임은 근반응성을 향상시켰다. 승마운동기는 전신운동효과에 매우 긍정적이며, 향후 고령자 및 장애인에게 효과가 있다고 판단된다.