A Computer-based Finger-tapping System for Evaluating Movement of the Affected Hand Following Stroke: A Pilot Study

Son, Jongsang,Ko, A Ra,Lee, Young Hee,Kim, Youngho 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.11

The objective of this study was to develop a computer-based finger-tapping system and to investigate whether the system is effective for evaluating motor function by performing pilot tests of the effects of three interventions, transcranial direct current stimulation (tDCS), peripheral sensory stimulation (PSS), and PSS combined with tDCS (PSS + tDCS), on the movement of the affected hand in stroke patients. The developed system consists of two parts, the finger-tapping input system and finger-tapping analysis software. The finger-tapping input system can detect the states of four buttons and transmit these states to the finger-tapping analysis software, which measures the reaction time. Three stroke patients participated in an experimental session to test the effects of each intervention on motor performance. Each session included three blocks for the determination of (1) baseline of motor performance (Base), (2) the motor performance after each form of stimulation (Pre), and (3) the motor performance following motor training and rest (Post). The results showed that the mean response times for all blocks (Base, Pre, and Post) did not differ significantly with tDCS and PSS, but significant decreases were found between Base and Post and between Pre and Post. In addition, there was no significant difference among the interventions at Pre; however, PSS + tDCS facilitated considerably greater training effects than tDCS or PSS at Post. The developed system was able to evaluate motor function through motor training after a combination of PSS and tDCS. In the near future, we plan to apply the developed system to more patients with relatively good motor function to extend our findings to a general outcome, and expect that these results could be used to design an appropriate rehabilitative approach.

발뒤꿈치들기 시 근력 추정을 위한 혼합 정적 최적화

손종상(Jongsang Son),손량희(Ryanghee Sohn),김영호(Youngho Kim) Korean Society for Precision Engineering 2009 한국정밀공학회지 Vol.26 No.3

Determination of Optimal Riding Positions using Muscle Co-Contraction on Upper Extremity during Manual Standing Wheelchair Propulsion

Ryu, Jeseong,Son, Jongsang,Kim, Sungjoong,Kim, Jongman,Ahn, Soonjae,Kim, Youngho Korean Society for Precision Engineering 2018 International Journal of Precision Engineering and Vol.19 No.4

A newly designed standing wheelchair that moves even while standing posture has been developed to improve the health and the quality of life for wheelchair users. However, this standing wheelchair has hand rims separate from the wheels, likely affecting the biomechanical characteristics and the efficiency of propulsion. Thus, this study aimed to propose a method to determine the optimal riding position by evaluating muscle activation during manual standing wheelchair propulsion. Ten elderly male subjects were asked to propel the hand rims with nine different seat (while sitting) and footrest (while standing) positions. During the experiments, kinematic data were obtained using a 3D motion capture system and sEMG measurement system, respectively. Simultaneously, surface electromyography signals were recorded from eleven muscles on the right side of the trunk and the upper extremity to evaluate relative iEMG and muscle co-contraction ratio. The muscle co-contraction ratio was higher at positions (upward and backward directions) distant from the hand rim and lower at positions (downward and forward directions) close to the hand rim. These results indicate that decreased distance from the hand rim enhances joint stability and decreases muscle co-contraction. These results also showed a good similarity with our previous study using energy expenditure method.

Consistency of the Optimized Bandwidth in Filter-based Fatigue Index

Kim, Jungyoon,Son, Jongsang,Kim, Youngho Korean Society for Precision Engineering 2014 International Journal of Precision Engineering and Vol.15 No.11

In this study, we evaluated the cut-off frequency of the filter-based fatigue index using surface electromyography (EMG) signals from different upper and lower extremity muscles under different exercise conditions. Twenty seven subjects participated in isotonic knee extension exercises, fourteen subjects in isotonic elbow flexion and isokinetic knee extension exercises, and twenty subjects in isometric knee extension, isotonic ankle dorsiflexion, and isotonic elbow extension exercises. EMG signals were obtained from right rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps brachii (BB), triceps brachii (TC), and tibialis anterior (TA) muscles during exercises. The filter-based fatigue index was compared with sEMG-based fatigue indices such as mean root-mean-square (RMS) values, median frequency, Dimitrov spectral index, and Gonzalez-Izal wavelet index. Results showed that optimized cut-off values for all muscles and all exercises approximated to 350 Hz. This implies that the cut-off frequency of 350 Hz is appropriate for general use, showing better determination coefficient with biomechanical fatigues such as joint torques and powers than the other fatigue indices in different muscles during different exercises.

A Novel Short-Time Fourier Transform-Based Fall Detection Algorithm Using 3-Axis Accelerations

Shin, Isu,Son, Jongsang,Ahn, Soonjae,Ryu, Jeseong,Park, Sunwoo,Kim, Jongman,Cha, Baekdong,Choi, Eunkyoung,Kim, Youngho Hindawi Limited 2015 Mathematical problems in engineering Vol.2015 No.-

<P>The short-time Fourier transform- (STFT-) based algorithm was suggested to distinguish falls from various activities of daily living (ADLs). Forty male subjects volunteered in the experiments including three types of falls and four types of ADLs. An inertia sensor unit attached to the middle of two anterior superior iliac spines was used to measure the 3-axis accelerations at 100 Hz. The measured accelerations were transformed to signal vector magnitude values to be analyzed using STFT. The powers of low frequency components were extracted, and the fall detection was defined as whether the normalized power was less than the threshold (50% of the normal power). Most power was observed at the frequency band lower than 5 Hz in all activities, but the dramatic changes in the power were found only in falls. The specificity of 1–3 Hz frequency components was the best (100%), but the sensitivity was much smaller compared with 4 Hz component. The 4 Hz component showed the best fall detection with 96.9% sensitivity and 97.1% specificity. We believe that the suggested algorithm based on STFT would be useful in the fall detection and the classification from ADLs as well.</P>

3D Motion Analysis and Musculoskeletal Modeling on Changes in Muscle Length of Lower Limbs for Hemiplegic Walking

Sungjae Hwang,Jongsang Son,Yujin Shin,Jungmi Park,Youngho Kim 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7

Many studies have been unsuccessful to classify biomechanical characteristics of pathological gaits in hemiplegic patients using joint motions of the lower extremity. In this paper, we analyzed changes in muscle length of lower limbs for hemiplegic walking by using the 3D motion analysis and the musculoskeletal modeling to determine gait patterns. Twenty young healthy volunteers and three hemiplegic patients participated in this study. 3D motion analyses were performed by using six infra-red cameras and four force plates. The musculoskeletal model was made based on subjects' anthropometric data and 3D motion capture data. The musculoskeletal model included twelve major lower extremity muscles based on the modified Hill-type muscle model in each lower limb. Results showed that insufficient push-off was found during pre-swing in hemiplegic walking, without showing enough contraction of gastrocnemius and soleus. Excessive ankle dorsiflexion was also found due the contracture of tibialis anterior. Semimembranosus was shown to be tighter and thus knee flexion was larger during loading response than those in the normal subjects. Changes in muscle length of extensor muscles were also very similar to joint motions in the sagittal plane. These results could be very useful to classify and to characterize various abnormal gait patterns.

Experimental and numerical study of electrochemical nanomachining using an AFM cantilever tip

Lee, Gyudo,Jung, Huihun,Son, Jongsang,Nam, Kihwan,Kwon, Taeyun,Lim, Geunbae,Kim, Young Ho,Seo, Jongbum,Lee, Sang Woo,Yoon, Dae Sung IOP Pub 2010 Nanotechnology Vol.21 No.18

<P>We fabricated nanopatterns on Cu thin films via an electrochemical route using an atomic force microscope (AFM). Experimental results were compared with an equivalent electrochemical circuit model representing an electrochemical nanomachining (ECN) technique. In order to precisely construct the nanopatterns, an ultra-short pulse was applied onto the Cu film through the AFM cantilever tip. The line width of the nanopatterns (the lateral dimension) increased with increased pulse amplitude, on-time, and frequency. The tip velocity effect on the nanopattern line width was also investigated. The study described here provides important insight for fabricating nanopatterns precisely using electrochemical methods with an AFM cantilever tip. </P>

Changes of Shoulder, Elbow, and Wrist Stiffness Matrix Post Stroke

Li-Qun Zhang,Jongsang Son,Hyung-Soon Park,Sang Hoon Kang,Yunju Lee,Yupeng Ren IEEE 2017 IEEE transactions on neural systems and rehabilita Vol.25 No.7

<P>Stroke affects multiple joints in the arm with stereotypical patterns of arm deformity involving the shoulder, elbow, wrist, and hand and with disrupted coordination of multiple joints in active movements. However, there is a lack of systematicmethods to evaluatemulti-joints and multi-degree of freedoms (DOF) neuro-mechanical changes, especially for complex systemswith three ormore joints/ DOFs involved. This paper used a novel systematic method to characterize dynamics and control of the shoulder, elbow, and wrist of the human arm individually and simultaneously, including the couplings across themultiple joints during controlled movements. A novel method was developed to decompose the complex system into manageable single-joint level for more reliable characterizations. The method was used in clinical studies to characterize the multi-joint changes associated with spastic impaired arm of 11 patients post stroke and 12 healthy controls. It was found that stroke survivors showed not only increased stiffness at the individual joints locally but also significantly higher couplings across the joints. The relative increases in couplings are often higher than that of the local joint stiffness. The multi-joint characterization provided a tool to characterize impairment of individual patients, which would allow more focused impairment-specific treatment. In general, the decomposition method can be used for even more complex systems, making characterization of intractable system dynamics of three or more joints/DOFs manageable.</P>

편향하중 조건 보행시 인체의 적응 작용에 대한 분석

김현동(Hyun Dong Kim),손종상(Jongsang Son),김한성(Han Sung Kim),김영호(Youngho Kim),임도형(Dohyung Lim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

The trunk is inclined to the loaded side when carrying an object as one of activities of daily living. As the reaction to this behavior the human body may be inclined to his/her trunk to unloaded side. The present study investigated the biomechanical effects of weight variation for sided load carriage during walking upon joint moments and muscle torques, through the tracker agent and joint driving dynamic analysis. To perform the experiment one male was selected as subject for the study. Gait analysis was performed by using a 3D motion analysis system. Thirty nine 14㎜ reflective markers, according to the plug-in marker set, were attached to the subject. We used BRG.LifeMOD(Biomechanics Research Group, Inc., USA), for skeletal modeling and inverse and joint driving dynamic simulation during one gait cycle. In walking with a sided load carriage, the subject modeled held the carriage with the right hand, which weighed 0, 5, 10, 15㎏, 20㎏ respectively. The result of this simulation showed that knee and hip in the coronal plane were inclined to the loaded side and loaded side had larger moments as the sided load carriage was increased. On the other hand thoracic and lumbar in the coronal plane had larger negative values as the sided loaded carriage was increased. The thoracic and lumbar in the transverse plane also had larger values as the sided load was increased. And the several muscles of loaded side were increased as increasing sided load. It could be concluded that human body is adopted to side loaded circumstances by showing more biologic force. These results could be very useful in analysis for delivery motion of daily life.

마비환자의 보행훈련을 위한 로봇형 보행훈련 시스템 개발

황성재(Sungjae Hwang),김정윤(Jungyoon Kim),손종상(Jongsang Son),손량희(Ryanghee Sohn),김영호(Youngho Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

In this study, we developed a robotic gait training system which induces the active gait training based on predefined continuous proper lower extremity joint movements for the paralysis. AC servo motors and linear actuators were used to control hip and knee joints of patients and the weight support system was used to support the patient's weight during the gait training. We also implemented a GUI program to set the gait training pattern with several training parameters and to confirm states of patients and the system through the visual feedback. The effectiveness of the gait training system will be determined by the long-term clinical experiments in the future. We expect that the developed robotic gait training system could be applied very practically to recover gait abilities for persons with gait disorder.