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PZT 액추에이터와 PVDF센서를 이용한 외팔보의 손상 진단에 관한 연구
권대규(Tae-Kyu Kwon),임숙정(Suk-Jeong Lim),유기호(Kee-Ho Yu),이성철(Seong-Cheol Lee) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.5
This paper presents the study on damage diagnosis of an intelligent cantilevered beams using PZT actuator and PVDF sensor. This study provides the theoretical and experimental verification to examine structural damage. Time domain analysis for the non-destructive detection of damage is presented by parameterized partial differential equations and Galerkin approximation techniques. The time histories of the vibration response of structure were used to identify the presence of damage. Furthermore, this systematic approach permits one to use the piezomaterials to both excite and sense the vibration of structures. We also carried out the experimental verification about reliability of theoretical methods for detecting the damage of a composite beam with PZT actuator and PVDF sensor. Experimental results are presented from tests on cantilevered composite beams which is damaged at different location and different dimensions. The results were compared with the simulation results. Good agreement between the results was found for the time shifts and amplitude difference in transients response of the cantilevered beam.
권대규(Tae-Kyu Kwon),박용군(Yong-Jun Piao),김동욱(Dong-Wook Kim),황지혜(Ji-Hye Hwang),김남균(Nam-Gyun Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
We investigated the training effect of postural control for the elderly adults using a training system for postural control that we developed. 15 healthy elderly subjects were in the training group. 15 were as the control group. The training group participated in the training 3 times a week for 8 weeks in 1 hour sessions. To confirm the training effect, we measured relevant parameters such as the time of timed up and go test, and the sway path of center of pressure before and that after the training. The results showed that this training system could successfully improve the postural control capability of the elderly adults. Moreover, the significant improvement in the postural capability of the elderly subjects suggested that elderly subjects could benefit more from the training using the system for the improvement of the ability of postural control.
MR 회전 브레이크를 이용한 하지 근력 증진용 헬스 자전거 개발
권대규(Tae-Kyu Kwon),김경(Kyung Kim),박용군(Young-Gyun Piao),허민,강승록(Seung-Rok Kang) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
In this study, a new bicycle ergometer system using the Magneto-Rheological(MR) rotary brake was developed to improve muscular strength for the rehabilitation of hemiplegia patients to reduce uneven pedaling characteristics. The friction load of the MR rotary brake is adjusted according to muscle strength of the subjects. The characteristic of muscular strength was studied with various friction loads of MR rotary brake. The friction load was occurred with the current, applied to the MR rotary brake. Experiments was composed of several cycling trials for various friction loads. In training programs involving muscle improvement, it is necessary to confirm muscle activity and fatigue. To measure the muscle activity and fatigue, EMG signals of rectus femoris (RF), biceps femoris (BF), tensor fasciae latae (TFL), vastus lateralis (VL), vastus medialis (VAS), gastrocnemius (GAS), tibialis anterior (TA) and soleus (SOL) muscles were collected with surface electromyography and analyzed into time and frequency domain. A series of experiments were carried out with and without the engagement of this real-time control mode of MR rotary brake at different pedaling rate to find out the effect of the real-time control mode. The characteristics of the pedaling for these specific conditions were analyzed based on the variations in angular velocities of the pedal unit. The results showed that the variations in the angular velocities were decreased by 42.9% with the control mode. The asymmetry of pedaling between dominant and non-dominant leg was 19.63% in non-control mode and 1.97% in the control mode. The characteristics of electromyography(EMG) in the lower limbs were also measured. The observation showed that Integrated EMG(IEMG) reduced with the control mode. Therefore, the new bicycle system using MR brake with the real time control of mechanical resistance was found to be effective in recovering the normal pedaling pattern by reducing unbalanced pedaling characteristics caused by disparity of muscular strength between affected and unaffected leg.
권대규(Tae-Kyu Kwon),김재준(Jae-Jun Kim),김경(Kyung Kim),이찬기(Chan-Ki Lee),김동원(Dong-Won Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Since driving include complicated actions that require a variety of ability and cause extreme concentration or strain, divers tend to feel tired easily. However, divers can't recognize fatigue degree by himself and accordingly the methods to measure quantitative fatigue degree exactly is quite difficult to be secured. In this study, the most efficient driving posture was suggested based on the analysis of quantitative muscular strength and fatigue degree according to posture. The driver whom we experimented included 9 commercial bus drivers. We also analyzed quantitative legs' muscular strength according be operating each pedal, left and right then we analyzed muscular strength and muscular fatigue degree according to driving pattern while driving commercial buses. And then we suggested the most efficient driving posture.