Fingertip Force and Muscle Activation Patterns at Varying grasp Objects

Suji Park(Suji Park),Juhyun Park(Juhyun Park),Seyeon Oh(Seyeon Oh),Chaeyeon Heo(Chaeyeon Heo),Sieun Ho(Sieun Ho),Seonhong Hwang(Seonhong Hwang) 호서대학교 기초과학연구소 2022 기초과학연구 논문집 Vol.30 No.1

In this study, we tried to collect and analyze the kinetic and neurological information such as finger-tip forces and EMG for several representative (the most commonly used) grasp movements to explore their force and muscle activation patterns based on the newly defined grasp taxonomy. Ten able-bodied (five males, five females) volunteered to participate and they performed five different grasp tasks: holding a bottle (Bottle), turning a doorknob (Knob), cutting with a knife (Knife), brushing with a toothbrush (Toothbrush), holding a thick book (Book) after we attached five force sensitive resistor (FSR) sensors on the tip of fingers and four surface electromyogram (sEMG) electrodes on the lower arm of the subject’s dominant hand. Root Mean Square (RMS) and Mean Absolute Value (MAV) from the mean maximum values of sEMG(%) and fingertip force(kgf) of all ten subjects were extracted as features. The classification from the feature dataset using convolutional neural network (CNN) was applied and analyzed the results of accuracy and repeatability. The mean maximum values of EMG and fingertip forces during five different grasp tasks, and the MAV and RMS which were extracted features from the above were compared with task pairs. They showed significant differences in comparison of four pairs of tasks which were Bottle and Knife (p = 0.005 in both MAV and RMS), Bottle and Toothbrush (p = 0.005in both MAV and RMS), Bottle and Book (p = 0.013 in both MAV and RMS), Knob and Toothbrush (p = 0.047 in MAV and p = 0.028 in RMS). The classification accuracy of the Bottle grasp task was the largest at 60% (true positive predictive rate is 60% and false postive rate is 40%), while the other tasks showed an 30-40% of accuracy. Repeatability was 60% in the Bottle task and 50% in the Knob task, and those of the other tasks were ranged 30-40%. Overall, it is believed that the small number of samples in the study is the main reason of the low accuracy and repeatability of the classification. A total of nine variables (four sEMG and five forces) showed different significances in paired mean comparisons for five grasp tasks (graspping a bottle, turning a doorknob, cutting with a knife, brushing teeth with a toothbrush, holding a thick book). A comparison of the reduced variable from feature extraction also showed different classification accuracy for five grasp tasks.

Effects of Neuromuscular Electrical Stimulation Induced Eccentric Contraction Training on Muscle Activation and Thickness

Seonhong Hwang,Heewon Park,Minwoo Seon,Yuik Moon,Suhui An,Jongsang Son 호서대학교 기초과학연구소 2023 기초과학연구 논문집 Vol.31 No.1

In this study, we investigate the effects of neuromuscular electrical stimulation (NMES)-induced eccentric contraction training for two weeks on muscle strength, activation level, and muscle architecture in healthy people. Six non-disabled (4 male, 2 female) volunteered to participate. The ultrasonographic images and dorsiflexion forces were measured when subjects performed the full relaxation, maximum voluntary isometric contraction (MVIC), and NMES-induced maximum involuntary isometric contraction of their tibialis anterior muscles in both pre- and post-test. After a two-week training period, the changes in the mean maximum NMES force ratio increased from 72.5 % to 88.92 %. The changes in the TA thickness during MVIC decreased significantly from 0.22 cm to 0.11 cm. The NMES-induced eccentrical contraction training described here effectively increases muscle strength with less muscle thickness changes after two weeks of training. This training technique may have a role in neuromuscular rehabilitation.

충청남도 실내라돈 분포현황 및 지질과의 상관성 조사

김선홍(Seonhong Kim),유주희(Juhee Yoo),김가현(Gahyeon Kim),박보람(Boram Park),이정섭(Jungsub Lee),이종천(Jongchun Lee) 대한지질학회 2022 대한지질학회 학술대회 Vol.2022 No.10

Changes of gait characteristics in a child with femoral nerve injury: a 16-month follow-up case study

Hwang, Seonhong,Park, Jeong-Mee,Kim, Youngho De Gruyter 2016 Biomedizinische Technik. Biomedical engineering Vol.61 No.3

<P><B>Abstract</B></P><P>An 11-year-old child was able to walk independently even though he had injured his femoral nerve severely due to a penetrating wound in the medial thigh. In this study, gait analysis was conducted five times totally for 16 months to observe the characteristics of the gait parameters, which enabled him to walk independently. The cadence, walking speed, stride length, step length, stride time, step time, double limb support, and single limb support all improved after the third test (GA3). Insufficient knee flexion during the stance phase, that was the main problem of the subject, improved from 0.96° to the normal level of 17.01°. Although hip extension was also insufficient at the first test it subsequently improved and reached the normal range at the GA5. The peaks of the ground reaction force curve were low at the initial tests. However, these eventually improved and reached the reference values. The knee extensor moment during the stance phase increased markedly at the last test. Although the child lost his femoral nerve function, he was able to walk independently by compensating for the major function of the rectus femoris. In order to facilitate shock-absorption and move the feet forward, he reduced both gait speed and stride length, respectively. The results of this study are expected to provide insight into how clinicians set up their therapy goals, while considering compensations and changes over time.</P>

Comparison of Gait Phase Detection Systems for Automatic FES Walking

Sunwoo Park,Sungjae Kang,Seonhong Hwang,Youngho Kim 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7

A simple, accurate gait phase detection is essential for the efficient application of the automatic FES walking system. Two different gait phase detection systems have been developed and compared in this study: one using a tilt sensor and the other using combinations of FSR sensors and a gyrosensor. Gait events were determined by the three-dimensional motion analysis system. The FSR-gyro sensor system, mounting four FSR sensors on the heel, 1<SUP>st</SUP> and 4<SUP>th</SUP> metatarsal heads and hallux and a gyrosensor on the heel, successfully detected various gait events including initial contact(IC), foot flat(FF), Heel off(HO) and Swing(SW). A miniaturized tilt sensor, mounted on the shank, also successfully detected IC and FO using the magnitude and the time duration of sensor signals. In addition, the tilt sensor system could detect the 1<SUP>st</SUP><SUP></SUP> TV and the 2<SUP>nd</SUP> TV, since the sensor generates offset voltage at the time of tibia vertical(TV). Even though the FSR-gyro sensor system might be more reliable for the gait phase detection, the simple tilt sensor system is not hindered by cables from the foot and could stimulate limbs at the same places where the detection is made.

분사형 초공동 수중운동체의 Planing 회피에 대한 연구

박종열(Jongyeol Park),김선홍(Seonhong Kim),김낙완(Nakwan Kim) 대한조선학회 2016 大韓造船學會 論文集 Vol.53 No.3

The Analysis of GRF during Golf Swing for the different Slope

Gonsung Moon,Hueseok Choi,Seonhong Hwang,Sunwoo Park,Jungyoon Kim,Youngho Kim 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7

The purpose of this study is to determine the characteristics of ground reaction force(GRF) in golf swing for the flat lie, the uphill lie and downhill lie of 10 degrees. Eight right-handed professional golfers were selected for the experiment and the 7 iron club was used. The GRF of the right foot was larger on the flat lie than the uphill lie in the lateral direction and the GRF of the left foot was larger on the flat lie than the uphill lie in medial direction. The GRF of both feet showed almost the same between flat lie and uphill lie on the anterior-posterior direction, but the GRF of both feet on the down hill lie was lower than the flat lie during the back swing phase in the both direction. The vertical GRF of the right foot was larger on the uphill lie than the flat lie, but it was larger in the flat lie than the downhill lie. The vertical GRF of the left foot was larger in the downhill lie than the flat lie, but it was larger in flat lie than uphill lie. The slopes would have negative effects to provide the angular momentum during back swing, restricting pelvic and trunk rotations, and to provide the precise timing and strong power during down swing.

A Comparison Study on Reinforcement Behaviors of Functional Fillers in Nitrile Rubber Composites

( Yoonjae Seong ),( Harim Lee ),( Seonhong Kim ),( Chang Hyun Yun ),( Changsin Park ),( Changwoon Nah ),( Gi-bbeum Lee ) 한국고무학회 2020 엘라스토머 및 콤포지트 Vol.55 No.4

To investigate the reinforcing effects of functional fillers in nitrile rubber (NBR) materials, high-structure carbon black (HS45), coated calcium carbonate (C-CaCO₃), silica (200MP), and multi-walled carbon nanotubes (MWCNTs) were used as functional filler, and carbon black (SRF) as a common filler were used for oil-resistant rubber. The curing and mechanical properties of HS45-, 200MP-, and MWCNT-filled NBR compounds were improved compared to those of the SRF-filled NBR compound. The reinforcing effect also increased with a decrease in the particle size of the fillers. The CCaCO₃- filled NBR compound exhibited no reinforcing effect with increasing filler concentration because of their large primary particle size (2 μm). The reinforcing behavior based on 100% modulus of the functional filler based NBR compounds was compared by using several predictive equation models. The reinforcing behavior of the C-CaCO3-filled NBR compound was in accordance with the Smallwood-Einstein equation whereas the 200MP- and MWCNT-filled NBR compounds fitted well with the modified Guth-Gold (m-Guth-Gold) equation. The SRF- and HS45-filled NBR compounds exhibited reinforcing behavior in accordance with the Guth-Gold and m-Guth-Gold equations, respectively, at a low filler content. However, the values of reinforcement parameter (100M_f/100M_u) of the SRF- and HS45-filled NBR compounds were higher than those determined by the predictive equation model at a high filler content. Because the chains of SRF composed of spherical filler particles are similarly changed to rod-like filler particles embedded in a rubber matrix and the reinforcement parameter rapidly increased with a high content of HS45, the higher-structured filler. The reinforcing effectiveness of the functional fillers was numerically evaluated on the basis of the effectiveness index (φ_SRF/φf) determined by the ratio of the volume fraction of the functional filler (φf) to that of the SRF filler (φSRF) at three unit of reinforcing parameter (100M_f/ 100M_u). On the basis of their effectiveness index, MWCNT-, 200MP-, and HS45-filled compounds showed higher reinforcing effectiveness of 420%, 70%, and 20% than that of SRF-filled compound, respectively whereas C-CaCO₃-filled compound exhibited lower reinforcing effectiveness of -50% than that of SRF-filled compound.

영상분석을 통한 버스운전자 부주의 유형

Kyung-ImChoi,Ju-Young Kim,Kwamgho Kim,Nayoung Shon,Jae Hoon Kim,Seonhong Park,Youngdal Oh 대한인간공학회 2016 대한인간공학회 학술대회논문집 Vol.2016 No.06