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Jeong-woo Seo

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Noel B. Salazar

KU Leuven

Sebahattin Devecioglu

University of Firat

Cristina Jönsson

University of the West Indies- Cave Hill (Barbados)

University of Algarve

University of Eastern Finland

Sergio Lambertucci

Universidad Nacional del Comahue

Anna Carr (ex Thompson/Thompson-Carr)

University of Otago

Dr. Eluvathingal Antony Jayson

Kerala Forest Research Institute

University of Bath

Malte Steinbrink

Universität Passau

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Papers by Jeong-woo Seo

Development and Application of a Stability Index Estimation Algorithm Based on Machine Learning for Elderly Balance Ability Diagnosis in Daily Life

Bioengineering, Aug 8, 2023

Background: The stability index estimation algorithm was derived and applied to develop and imple... more Background: The stability index estimation algorithm was derived and applied to develop and implement a balance ability diagnosis system that can be used in daily life. Methods: The system integrated an approach based on sensory function interaction, called the clinical test of sensory interaction with balance. A capacitance and resistance sensing type force mat was fabricated, and a stability index prediction algorithm was developed and applied using the center of pressure variables. The stability index prediction algorithm derived a center of pressure variable for 103 elderly people by Nintendo Wii Balance Board to predict the stability index of the balance system (Biodex SD), and the accuracy of this approach was confirmed. Results: As a result of testing with the test set, the linear regression model confirmed that the r-value ranged between 0.943 and 0.983. To confirm the similarity between the WBB and the flexible force mat, each measured center of pressure value was inputted and calculated in the developed regression model, and the result of the correlation coefficient validation confirmed an r-value of 0.96. Conclusion: The system developed in this study will be applicable to daily life in the home in the form of a floor mat.

Sensory Interaction and Balancing Ability Evaluation of the Elderly Using a Simplified Force Plate System

Sensors, Nov 17, 2022

The Wii balance board (WBB) is a simplified force plate system used to evaluate the balancing abi... more The Wii balance board (WBB) is a simplified force plate system used to evaluate the balancing ability of the elderly via a sensory interaction task to confirm a significant standing balance index. The accuracy of this system has been verified in previous studies. In this study, an instrumented and modified clinical test of sensory interaction on balance (i-mCTSIB) was performed on 84 elderly subjects, and the variables for center of pressure (CoP) were calculated using WBB for each task condition. The results indicate that the visual condition has a significant effect on the sway proprioceptive sensory variables with a foam condition as their complexity increases. In addition, the correlation between the variable and Berg Balance Scale was not confirmed since CTSIB is a sensory interaction on balance ability. Therefore, WBB can be used to evaluate balancing ability based on sensory interactions consisting of the surface condition.

The necessity of developing a Gait Meridian muscle model

Integrative Medicine Research

Development of Gait Measurement System Combined with IMU and Loadcell Insole: A Pilot Study

Journal of the Korean Society for Precision Engineering

Comparison of Muscle Frequency Characteristics According to Saddle Height during Cycle Pedaling

Fall prediction model for the elderly using postural sway

2017 IEEE International Conference on Bioinformatics and Biomedicine (BIBM), 2017

Purpose of this study was to develop a fall prediction model based on various variables with line... more Purpose of this study was to develop a fall prediction model based on various variables with linear and nonlinear analysis using postural sway. The included variables in the regression model were Sample Entropy, Largest Lyapunov exponent and Hurst exponent in anterior-posterior direction, which are nonlinear variables. Accuracy of this regression model for fall prediction was 81.9%.

A Preliminary Study of Age-Specific Differences in Balance, Muscle Strength, and Postural Sway for the Risk of Falling

Journal of Mechanics in Medicine and Biology, 2017

Fall is the main cause of activity decline for the elderly. In general, it has been known to be c... more Fall is the main cause of activity decline for the elderly. In general, it has been known to be closely related to decline in muscle strength and physical balance. The age profile of the elderly has a very wide range from 60 to 90 or more. Therefore, this study was to determine age-specific risk factors for falling in elderly individuals. Elderly females were included either in the old group ([Formula: see text]75 years; [Formula: see text], with 11 fallers and 24 nonfallers) or the older group ([Formula: see text]75 years; [Formula: see text], with 14 fallers and 22 nonfallers). The following were assessed and compared between the age-based groups and between fall-based subgroups (fallers and nonfallers within a given age group): height, weight, mental state, balance on the Berg balance scale (BBS), muscle strength of nine muscle groups, and 20 variables of postural sway. The two age-based groups differed significantly in terms of height, weight, balance, and postural sway (total s...

Relationship between Lower -Limb Joint Angle and Muscle Activity due to Saddle Height during Cycle Pedaling

Korean Journal of Sport Biomechanics, 2012

The purpose of this study was to investigate the effects of different saddle heights on lower-lim... more The purpose of this study was to investigate the effects of different saddle heights on lower-limb joint angle and muscle activity. Six elite cyclists(age: 32.2±5.2 years, height: 171.0±3.5 cm, weight: 79.7±5.6 kg, cycle career: 13±6.2 years) participated in three min. submaximal(90 rpm) pedaling tests with the same load and cadence based on saddle heights where subject's saddle height was determined by his knee flexion angle when the pedal crank was at the 6 o'clock position. Joint angles(hip, knee, ankle joints) and the activity of lower limb muscles(biceps femoris(BF), vastus lateralis(VL), tibialis anterior(TA) and gastrocnemius medial(GM)) were compared by measuring 3D motion and electromyography(EMG) data. Results showed that there were significant differences in minimum hip & knee joint angle and range of motion of hip and knee joint between saddle heights. Onset timing and integrated EMG of only BF among 4 muscles were significantly different between saddle heights. Especially there was a negative relationship between minimum hip joint angle and onset timing of BF in most subject, which means that onset timing of BF became fast as the degree of bending of the hip joint became larger by saddle height. Optimal pedaling will be possible through increased amount of muscle activation due to the appropriate burst onset timing by proper pedaling posture with adjusted saddle height.

Technical Note : Development of Electric Riding Machine for Cycle Fitting

Korean Journal of Sport Biomechanics, 2012

The purpose of this study was to develop an electric riding machine for cycle fitting to control ... more The purpose of this study was to develop an electric riding machine for cycle fitting to control riding posture easily, to measure frame size quantitatively, and to overcome disadvantages of the traditional systems. The electric riding machine consisted of actuator, load controller, and display & control unit. The actuator unit by BLDC(BrushLess Direct Current) motor drives the saddle height up and down, the crank forward and backward, the handlebar up and down, and the handlebar forward and backward. The load controller unit controls loads by Eddy current controller with electromagnet and aluminum circular plate. The display & control unit consisted of frame size controller and display panel which shows top tube length(485~663mm), head tube length(85~243mm), seat tube length(481~671mm), and seat tube angle(62.7~76.4˚). The range of frame size control for developed electric riding machine did not have difference compared to traditional commercial systems, but quantitative and precise control with 0.1 mm length and 0.1°angle was possible through digital measurement. Unlike traditional commercial systems, frame size control was possible during riding through motor driven method, thus fitting duration decreased. It is necessary for further improvement to have feedback from users. It is believed that developed electric riding machine can help to develop domestic fitting system.

Effects of Increased Saddle Height on Length and Activity Pattern of Vastus Lateralis and Biceps Femor is Muscle

Korean Journal of Sport Biomechanics, 2012

The purpose of this study was to investigate the effects of increased saddle height on the length... more The purpose of this study was to investigate the effects of increased saddle height on the length and activity pattern of vastus lateralis (VL) and biceps femoris (BF) muscle. To compare the effects of increased saddle height, Preferred (self-selected height of subject) and High saddle height (approximately 5% higher saddle height than self-selected) were used. Seven elite cyclists (career: 16.1±8.5 years) participated in 3 min. sub-maximal pedaling tests under the same cadence (90 RPM) and pedaling power (150 W). Hip and knee joint angles, and the length and activity of VL and BF were compared by measuring 3D motion and electromyography (EMG) data. Results showed that there were significant differences in peak extension timing of the hip joint angle and the range of motion of the hip and knee joint between different saddle heights. Although there were significant differences in muscle length of both muscles with increasing saddle height, the timing and amount of muscle activity differed only at the BF. These findings suggest that the timing and amount of bi-articular muscle activity (i.e. BF) can be altered by changing the saddle height. For practically applying these results, further study is necessary to evaluate the effects of various cadence and the pedaling power with various saddle heights.

Evaluation of Balance Ability of the Elderly Using Kinect Sensor

The Transactions of The Korean Institute of Electrical Engineers, 2017

Portable low-cost Kinect sensor was used to analyze standing balance ability of the elderly. Eigh... more Portable low-cost Kinect sensor was used to analyze standing balance ability of the elderly. Eighty subjects who can walk alone and have a normal cognitive level participated in this experiment. Based on Berg Balance scale (BBS) test with 52 points, subjects were divided into Healthy older (HO: 46 persons, BBS: 53.80 ± 1.19) and Impaired older (IO: 34 persons, BBS: 49.06 ± 2.03) group. Each subject performed 30 seconds four different standing balance tests (EO: Eyes Open, EC: Eyes Close, EOf: Eyes Open on foam, ECf: Eyes Close on foam). Five variables (Mean distance, Range of distance, Root mean square, Mean velocity, 95% ellipse area) were calculated from the hip joint center movement of Kinect sensor. Results showed that there were significant differences between groups for four different standing tests. Calculated variables from kinect sensor showed significant correlation with BBS score. Especially, mediolateral mean distance, mediolateral root mean square, mediolateral range of distance and 95% ellipse area showed discriminative ability for all tests. Mean values of variables of IO were higher than those of HO, which means the decreased balance ability in IO compared with HO. Therefore, it was possible to estimate simple balance assessment of the elderly using portable low-cost Kinect sensor.

Effects of Vertical Alignment of Leg on the Knee Trajectory and Pedal Force during Pedaling

Korean Journal of Sport Biomechanics, 2016

This study evaluated the vertical and horizontal forces in the frontal plane acting on a pedal du... more This study evaluated the vertical and horizontal forces in the frontal plane acting on a pedal due to the vertical alignment of the lower limbs. Method: Seven male subjects (age: 25.3 ± 0.8 years, height: 175.4 ± 4.7 cm, weight: 74.7 ± 14.2 kg, foot size: 262.9 ± 7.6 mm) participated in two 2-minute cycle pedaling tests, with the same load and cadence (60 revolutions per minute) across all subjects. The subject's saddle height was determined by the height when the knee was at 25 ° flexion when the pedal crank was at the 6 o'clock position (knee angle method). The horizontal force acting on the pedal, vertical force acting on the pedal in the frontal plane, ratio of the two forces, and knee range of motion in the frontal plane were calculated for four pedaling phases (phase 1: 330~30 °, phase 2: 30~150 °, phase 3: 150~210 °, phase 4: 210~330 °) and the complete pedaling cycle. The range of motion of the knee in the frontal plane was decreased, and the ratio of vertical force to horizontal force and overall pedal force in the complete cycle were increased after vertical alignment. The ratio of vertical force to horizontal force in the frontal plane may be used as an injury prevention index of the lower limb.

Reliability of the walking speed and gait dynamics variables while walking on a feedback-controlled treadmill

Journal of biomechanics, Jan 11, 2015

The purpose of this study is to identify the reliability of walking speed and gait dynamics measu... more The purpose of this study is to identify the reliability of walking speed and gait dynamics measured with a feedback-controlled treadmill and to assess the applicability of the treadmill to gait dynamics studies. The intraclass correlation coefficient (ICC) and the standard error of measurement (SEM) for the walking speed and the mean, variability (coefficient of variance, CV), and fractal dynamics (the scaling exponent α of detrended fluctuation analysis, DFA) of the stride time and stride length were used to evaluate the within-day and between-day reliability. Fifteen subjects walked on a feedback-controlled treadmill for three trials that were each more than 10min in length (within-day); this protocol was repeated on another day to identify the between-day reliability. The results showed that all variables were consistent for within-day and between-day reliability (ICC: 0.633-0.982, p<0.05; SEM: 0.02-0.43). The within- and between-day reliability of the walking speed and the m...

안면 움직임 분석을 통한 단음절 음성인식

The Transactions of The Korean Institute of Electrical Engineers, 2014

The purpose of this study was to extract accurate parameters of facial movement features using 3-... more The purpose of this study was to extract accurate parameters of facial movement features using 3-D motion capture system in speech recognition technology through lip-reading. Instead of using the features obtained through traditional camera image, the 3-D motion system was used to obtain quantitative data for actual facial movements, and to analyze 11 variables that exhibit particular patterns such as nose, lip, jaw and cheek movements in monosyllable vocalizations. Fourteen subjects, all in 20s of age, were asked to vocalize 11 types of Korean vowel monosyllables for three times with 36 reflective markers on their faces. The obtained facial movement data were then calculated into 11 parameters and presented as patterns for each monosyllable vocalization. The parameter patterns were performed through learning and recognizing process for each monosyllable with speech recognition algorithms with Hidden Markov Model (HMM) and Viterbi algorithm. The accuracy rate of 11 monosyllables recognition was 97.2%, which suggests the possibility of voice recognition of Korean language through quantitative facial movement analysis.

자전거 페달링 시 하지 정렬 평가를 위한 영상 시스템 개발

Korean Journal of Sport Biomechanics, 2012

Simple camera-based system for evaluation of lower limb alignment as a part of an automated cycli... more Simple camera-based system for evaluation of lower limb alignment as a part of an automated cycling fitting system was developed and verified in this study. Developed imaging system can evaluate lower limb alignment quantitatively during pedaling using a general camcorder and single marker attached on the knee. Threshold-based marker detection algorithm was proposed in this study. Experiment was carried out to compare the trajectory data from marker detection algorithm of the developed imaging system with the trajectory data from 3-D motion capture system. Results showed that average error between trajectories was 2.33 mm (0.92 %) in the vertical direction and 0.62 mm (1.86 %) in the medio-lateral direction. There existed significant correlation between two measured values (r=0.9996 in the vertical direction and r=0.9975 in the medio-lateral direction). It can be concluded that developed imaging system be applied to evaluate lower limb alignment which is an important factor for dynamic bicycle fitting.

Development of simple camera-based system for lower limb alignment evaluation during cycling

Simple camera-based system for evaluation of lower limb alignment as a part of an automated cycli... more Simple camera-based system for evaluation of lower limb alignment as a part of an automated cycling fitting system was developed and verified in this study. Developed imaging system can evaluate lower limb alignment quantitatively during pedaling using a general camcorder and single marker attached on the knee. Threshold-based marker detection algorithm with YCbCr color space was proposed in this study. Experiment was carried out to compare trajectory data from marker detection algorithm of the developed imaging system with trajectory data from 3-D motion analysis system. Result showed that average error between trajectories was 1.8mm (0.57%) of range of motion (ROM) of 326 mm in the vertical direction and 2.3mm (6.16%) of ROM of 37 mm in the medio-lateral direction. There existed significant correlation between two measured values (r=1.00 in the vertical direction and r=0.926 in the medio-lateral direction). It can be concluded that developed imaging system be applied to evaluate l...

Development and Application of Stability Index estimation Algorithm based on Machine Learning for Elderly Balance Ability Diagnosis in Daily Life

Background: The Stability Index estimation algorithm was derived and applied to develop and imple... more Background: The Stability Index estimation algorithm was derived and applied to develop and implement a balance ability diagnosis system that can be used at daily life. Methods: The system integrated an approach based on sensory function interaction, called the clinical test of sensory interaction with balance (CTSIB). The piezo-resistive force mat was fabricated, and a Stability Index prediction algorithm was developed and applied using the center of pressure (CoP) variables. The Stability Index prediction algorithm derived a CoP variable for 103 elderly people by Nintendo Wii Balance Board (WBB) to predict the Stability Index of the Balance System (Biodex SD). And, the accuracy was confirmed through the correlation between the real and predicted value. Results: As a result of testing with the test-set, the linear regression model confirmed that the r value ranged between 0.943 to 0.983. To confirm the similarity between the WBB and flexible force mat, each measured CoP value was i...

Forward and inverse dynamic study during pedaling: Comparison between the young and the elderly

Technology and health care : official journal of the European Society for Engineering and Medicine, Jan 29, 2016

As it is not easy to investigate various variables that affect exercise efficacies and cause inju... more As it is not easy to investigate various variables that affect exercise efficacies and cause injuries while pedaling in the actual experiment, especially for the elderly, the musculoskeletal model simulation with a comparison of measured electromyography (EMG) data could be used to minimize experimental trials. The measured EMG data were compared with the muscle activities from the musculoskeletal model through forward (FD) and inverse dynamic (ID) analysis. EMG was measured from eight young adult (20's) and eight elderly (70's) in three minutes pedaling with a constant load and 40 revolutions per minute (RPM) cadence. The muscles used for the analysis were the VastusLateralis, Tibialis Anterior, Bicep Femoris, and Gastrocnemius Medial. Pearson's correlation coefficients of the muscle activity patterns, on-off set, and peak timing at the maximum muscle activity were calculated and compared. BIKE3D and GaitLowerExtremity model were used for the FD and ID simulation. There...

Differences In Stress And Total Deformation Due To Muscle Attachment To The Femur

To achieve accurate and precise results of finite element analysis (FEA) of bones, it is importan... more To achieve accurate and precise results of finite element analysis (FEA) of bones, it is important to represent the load/boundary conditions as identical as possible to the human body such as the bone properties, the type and force of the muscles, the contact force of the joints, and the location of the muscle attachment. In this study, the difference in the Von-Mises stress and the total deformation was compared by classifying them into Case 1, which shows the actual anatomical form of the muscle attached to the femur when the same muscle force was applied, and Case 2, which gives a simplified representation of the attached location. An inverse dynamical musculoskeletal model was simulated using data from an actual walking experiment to complement the accuracy of the muscular force, the input value of FEA. The FEA method using the results of the muscular force that were calculated through the simulation showed that the maximum Von-Mises stress and the maximum total deformation in C...

A Study On Human Musculoskeletal Model For Cycle Fitting: Comparison With Emg

It is difficult to study the effect of various variables on<br> cycle fitting through actua... more It is difficult to study the effect of various variables on<br> cycle fitting through actual experiment. To overcome such difficulty,<br> the forward dynamics of a musculoskeletal model was applied to cycle<br> fitting in this study. The measured EMG data weres compared with the<br> muscle activities of the musculoskeletal model through forward<br> dynamics. EMG data were measured from five cyclists who do not<br> have musculoskeletal diseases during three minutes pedaling with a<br> constant load (150 W) and cadence (90 RPM). The muscles used for<br> the analysis were the Vastus Lateralis (VL), Tibialis Anterior (TA),<br> Bicep Femoris (BF), and Gastrocnemius Medial (GM). Person's<br> correlation coefficients of the muscle activity patterns, the peak timing<br> of the maximum muscle activities, and the total muscle activities were<br> calculated and compared. BIKE3D model of AnyBody (Anybodytech,<br> ...

Development and Application of a Stability Index Estimation Algorithm Based on Machine Learning for Elderly Balance Ability Diagnosis in Daily Life

Bioengineering, Aug 8, 2023

Background: The stability index estimation algorithm was derived and applied to develop and imple... more Background: The stability index estimation algorithm was derived and applied to develop and implement a balance ability diagnosis system that can be used in daily life. Methods: The system integrated an approach based on sensory function interaction, called the clinical test of sensory interaction with balance. A capacitance and resistance sensing type force mat was fabricated, and a stability index prediction algorithm was developed and applied using the center of pressure variables. The stability index prediction algorithm derived a center of pressure variable for 103 elderly people by Nintendo Wii Balance Board to predict the stability index of the balance system (Biodex SD), and the accuracy of this approach was confirmed. Results: As a result of testing with the test set, the linear regression model confirmed that the r-value ranged between 0.943 and 0.983. To confirm the similarity between the WBB and the flexible force mat, each measured center of pressure value was inputted and calculated in the developed regression model, and the result of the correlation coefficient validation confirmed an r-value of 0.96. Conclusion: The system developed in this study will be applicable to daily life in the home in the form of a floor mat.

Sensory Interaction and Balancing Ability Evaluation of the Elderly Using a Simplified Force Plate System

Sensors, Nov 17, 2022

The Wii balance board (WBB) is a simplified force plate system used to evaluate the balancing abi... more The Wii balance board (WBB) is a simplified force plate system used to evaluate the balancing ability of the elderly via a sensory interaction task to confirm a significant standing balance index. The accuracy of this system has been verified in previous studies. In this study, an instrumented and modified clinical test of sensory interaction on balance (i-mCTSIB) was performed on 84 elderly subjects, and the variables for center of pressure (CoP) were calculated using WBB for each task condition. The results indicate that the visual condition has a significant effect on the sway proprioceptive sensory variables with a foam condition as their complexity increases. In addition, the correlation between the variable and Berg Balance Scale was not confirmed since CTSIB is a sensory interaction on balance ability. Therefore, WBB can be used to evaluate balancing ability based on sensory interactions consisting of the surface condition.

The necessity of developing a Gait Meridian muscle model

Integrative Medicine Research

Development of Gait Measurement System Combined with IMU and Loadcell Insole: A Pilot Study

Journal of the Korean Society for Precision Engineering

Comparison of Muscle Frequency Characteristics According to Saddle Height during Cycle Pedaling

Fall prediction model for the elderly using postural sway

2017 IEEE International Conference on Bioinformatics and Biomedicine (BIBM), 2017

Purpose of this study was to develop a fall prediction model based on various variables with line... more Purpose of this study was to develop a fall prediction model based on various variables with linear and nonlinear analysis using postural sway. The included variables in the regression model were Sample Entropy, Largest Lyapunov exponent and Hurst exponent in anterior-posterior direction, which are nonlinear variables. Accuracy of this regression model for fall prediction was 81.9%.

A Preliminary Study of Age-Specific Differences in Balance, Muscle Strength, and Postural Sway for the Risk of Falling

Journal of Mechanics in Medicine and Biology, 2017

Fall is the main cause of activity decline for the elderly. In general, it has been known to be c... more Fall is the main cause of activity decline for the elderly. In general, it has been known to be closely related to decline in muscle strength and physical balance. The age profile of the elderly has a very wide range from 60 to 90 or more. Therefore, this study was to determine age-specific risk factors for falling in elderly individuals. Elderly females were included either in the old group ([Formula: see text]75 years; [Formula: see text], with 11 fallers and 24 nonfallers) or the older group ([Formula: see text]75 years; [Formula: see text], with 14 fallers and 22 nonfallers). The following were assessed and compared between the age-based groups and between fall-based subgroups (fallers and nonfallers within a given age group): height, weight, mental state, balance on the Berg balance scale (BBS), muscle strength of nine muscle groups, and 20 variables of postural sway. The two age-based groups differed significantly in terms of height, weight, balance, and postural sway (total s...

Relationship between Lower -Limb Joint Angle and Muscle Activity due to Saddle Height during Cycle Pedaling

Korean Journal of Sport Biomechanics, 2012

The purpose of this study was to investigate the effects of different saddle heights on lower-lim... more The purpose of this study was to investigate the effects of different saddle heights on lower-limb joint angle and muscle activity. Six elite cyclists(age: 32.2±5.2 years, height: 171.0±3.5 cm, weight: 79.7±5.6 kg, cycle career: 13±6.2 years) participated in three min. submaximal(90 rpm) pedaling tests with the same load and cadence based on saddle heights where subject's saddle height was determined by his knee flexion angle when the pedal crank was at the 6 o'clock position. Joint angles(hip, knee, ankle joints) and the activity of lower limb muscles(biceps femoris(BF), vastus lateralis(VL), tibialis anterior(TA) and gastrocnemius medial(GM)) were compared by measuring 3D motion and electromyography(EMG) data. Results showed that there were significant differences in minimum hip & knee joint angle and range of motion of hip and knee joint between saddle heights. Onset timing and integrated EMG of only BF among 4 muscles were significantly different between saddle heights. Especially there was a negative relationship between minimum hip joint angle and onset timing of BF in most subject, which means that onset timing of BF became fast as the degree of bending of the hip joint became larger by saddle height. Optimal pedaling will be possible through increased amount of muscle activation due to the appropriate burst onset timing by proper pedaling posture with adjusted saddle height.

Technical Note : Development of Electric Riding Machine for Cycle Fitting

Korean Journal of Sport Biomechanics, 2012

The purpose of this study was to develop an electric riding machine for cycle fitting to control ... more The purpose of this study was to develop an electric riding machine for cycle fitting to control riding posture easily, to measure frame size quantitatively, and to overcome disadvantages of the traditional systems. The electric riding machine consisted of actuator, load controller, and display & control unit. The actuator unit by BLDC(BrushLess Direct Current) motor drives the saddle height up and down, the crank forward and backward, the handlebar up and down, and the handlebar forward and backward. The load controller unit controls loads by Eddy current controller with electromagnet and aluminum circular plate. The display & control unit consisted of frame size controller and display panel which shows top tube length(485~663mm), head tube length(85~243mm), seat tube length(481~671mm), and seat tube angle(62.7~76.4˚). The range of frame size control for developed electric riding machine did not have difference compared to traditional commercial systems, but quantitative and precise control with 0.1 mm length and 0.1°angle was possible through digital measurement. Unlike traditional commercial systems, frame size control was possible during riding through motor driven method, thus fitting duration decreased. It is necessary for further improvement to have feedback from users. It is believed that developed electric riding machine can help to develop domestic fitting system.

Effects of Increased Saddle Height on Length and Activity Pattern of Vastus Lateralis and Biceps Femor is Muscle

Korean Journal of Sport Biomechanics, 2012

The purpose of this study was to investigate the effects of increased saddle height on the length... more The purpose of this study was to investigate the effects of increased saddle height on the length and activity pattern of vastus lateralis (VL) and biceps femoris (BF) muscle. To compare the effects of increased saddle height, Preferred (self-selected height of subject) and High saddle height (approximately 5% higher saddle height than self-selected) were used. Seven elite cyclists (career: 16.1±8.5 years) participated in 3 min. sub-maximal pedaling tests under the same cadence (90 RPM) and pedaling power (150 W). Hip and knee joint angles, and the length and activity of VL and BF were compared by measuring 3D motion and electromyography (EMG) data. Results showed that there were significant differences in peak extension timing of the hip joint angle and the range of motion of the hip and knee joint between different saddle heights. Although there were significant differences in muscle length of both muscles with increasing saddle height, the timing and amount of muscle activity differed only at the BF. These findings suggest that the timing and amount of bi-articular muscle activity (i.e. BF) can be altered by changing the saddle height. For practically applying these results, further study is necessary to evaluate the effects of various cadence and the pedaling power with various saddle heights.

Evaluation of Balance Ability of the Elderly Using Kinect Sensor

The Transactions of The Korean Institute of Electrical Engineers, 2017

Portable low-cost Kinect sensor was used to analyze standing balance ability of the elderly. Eigh... more Portable low-cost Kinect sensor was used to analyze standing balance ability of the elderly. Eighty subjects who can walk alone and have a normal cognitive level participated in this experiment. Based on Berg Balance scale (BBS) test with 52 points, subjects were divided into Healthy older (HO: 46 persons, BBS: 53.80 ± 1.19) and Impaired older (IO: 34 persons, BBS: 49.06 ± 2.03) group. Each subject performed 30 seconds four different standing balance tests (EO: Eyes Open, EC: Eyes Close, EOf: Eyes Open on foam, ECf: Eyes Close on foam). Five variables (Mean distance, Range of distance, Root mean square, Mean velocity, 95% ellipse area) were calculated from the hip joint center movement of Kinect sensor. Results showed that there were significant differences between groups for four different standing tests. Calculated variables from kinect sensor showed significant correlation with BBS score. Especially, mediolateral mean distance, mediolateral root mean square, mediolateral range of distance and 95% ellipse area showed discriminative ability for all tests. Mean values of variables of IO were higher than those of HO, which means the decreased balance ability in IO compared with HO. Therefore, it was possible to estimate simple balance assessment of the elderly using portable low-cost Kinect sensor.

Effects of Vertical Alignment of Leg on the Knee Trajectory and Pedal Force during Pedaling

Korean Journal of Sport Biomechanics, 2016

This study evaluated the vertical and horizontal forces in the frontal plane acting on a pedal du... more This study evaluated the vertical and horizontal forces in the frontal plane acting on a pedal due to the vertical alignment of the lower limbs. Method: Seven male subjects (age: 25.3 ± 0.8 years, height: 175.4 ± 4.7 cm, weight: 74.7 ± 14.2 kg, foot size: 262.9 ± 7.6 mm) participated in two 2-minute cycle pedaling tests, with the same load and cadence (60 revolutions per minute) across all subjects. The subject's saddle height was determined by the height when the knee was at 25 ° flexion when the pedal crank was at the 6 o'clock position (knee angle method). The horizontal force acting on the pedal, vertical force acting on the pedal in the frontal plane, ratio of the two forces, and knee range of motion in the frontal plane were calculated for four pedaling phases (phase 1: 330~30 °, phase 2: 30~150 °, phase 3: 150~210 °, phase 4: 210~330 °) and the complete pedaling cycle. The range of motion of the knee in the frontal plane was decreased, and the ratio of vertical force to horizontal force and overall pedal force in the complete cycle were increased after vertical alignment. The ratio of vertical force to horizontal force in the frontal plane may be used as an injury prevention index of the lower limb.

Reliability of the walking speed and gait dynamics variables while walking on a feedback-controlled treadmill

Journal of biomechanics, Jan 11, 2015

The purpose of this study is to identify the reliability of walking speed and gait dynamics measu... more The purpose of this study is to identify the reliability of walking speed and gait dynamics measured with a feedback-controlled treadmill and to assess the applicability of the treadmill to gait dynamics studies. The intraclass correlation coefficient (ICC) and the standard error of measurement (SEM) for the walking speed and the mean, variability (coefficient of variance, CV), and fractal dynamics (the scaling exponent α of detrended fluctuation analysis, DFA) of the stride time and stride length were used to evaluate the within-day and between-day reliability. Fifteen subjects walked on a feedback-controlled treadmill for three trials that were each more than 10min in length (within-day); this protocol was repeated on another day to identify the between-day reliability. The results showed that all variables were consistent for within-day and between-day reliability (ICC: 0.633-0.982, p<0.05; SEM: 0.02-0.43). The within- and between-day reliability of the walking speed and the m...

안면 움직임 분석을 통한 단음절 음성인식

The Transactions of The Korean Institute of Electrical Engineers, 2014

The purpose of this study was to extract accurate parameters of facial movement features using 3-... more The purpose of this study was to extract accurate parameters of facial movement features using 3-D motion capture system in speech recognition technology through lip-reading. Instead of using the features obtained through traditional camera image, the 3-D motion system was used to obtain quantitative data for actual facial movements, and to analyze 11 variables that exhibit particular patterns such as nose, lip, jaw and cheek movements in monosyllable vocalizations. Fourteen subjects, all in 20s of age, were asked to vocalize 11 types of Korean vowel monosyllables for three times with 36 reflective markers on their faces. The obtained facial movement data were then calculated into 11 parameters and presented as patterns for each monosyllable vocalization. The parameter patterns were performed through learning and recognizing process for each monosyllable with speech recognition algorithms with Hidden Markov Model (HMM) and Viterbi algorithm. The accuracy rate of 11 monosyllables recognition was 97.2%, which suggests the possibility of voice recognition of Korean language through quantitative facial movement analysis.

자전거 페달링 시 하지 정렬 평가를 위한 영상 시스템 개발

Korean Journal of Sport Biomechanics, 2012

Simple camera-based system for evaluation of lower limb alignment as a part of an automated cycli... more Simple camera-based system for evaluation of lower limb alignment as a part of an automated cycling fitting system was developed and verified in this study. Developed imaging system can evaluate lower limb alignment quantitatively during pedaling using a general camcorder and single marker attached on the knee. Threshold-based marker detection algorithm was proposed in this study. Experiment was carried out to compare the trajectory data from marker detection algorithm of the developed imaging system with the trajectory data from 3-D motion capture system. Results showed that average error between trajectories was 2.33 mm (0.92 %) in the vertical direction and 0.62 mm (1.86 %) in the medio-lateral direction. There existed significant correlation between two measured values (r=0.9996 in the vertical direction and r=0.9975 in the medio-lateral direction). It can be concluded that developed imaging system be applied to evaluate lower limb alignment which is an important factor for dynamic bicycle fitting.

Development of simple camera-based system for lower limb alignment evaluation during cycling

Simple camera-based system for evaluation of lower limb alignment as a part of an automated cycli... more Simple camera-based system for evaluation of lower limb alignment as a part of an automated cycling fitting system was developed and verified in this study. Developed imaging system can evaluate lower limb alignment quantitatively during pedaling using a general camcorder and single marker attached on the knee. Threshold-based marker detection algorithm with YCbCr color space was proposed in this study. Experiment was carried out to compare trajectory data from marker detection algorithm of the developed imaging system with trajectory data from 3-D motion analysis system. Result showed that average error between trajectories was 1.8mm (0.57%) of range of motion (ROM) of 326 mm in the vertical direction and 2.3mm (6.16%) of ROM of 37 mm in the medio-lateral direction. There existed significant correlation between two measured values (r=1.00 in the vertical direction and r=0.926 in the medio-lateral direction). It can be concluded that developed imaging system be applied to evaluate l...

Development and Application of Stability Index estimation Algorithm based on Machine Learning for Elderly Balance Ability Diagnosis in Daily Life

Background: The Stability Index estimation algorithm was derived and applied to develop and imple... more Background: The Stability Index estimation algorithm was derived and applied to develop and implement a balance ability diagnosis system that can be used at daily life. Methods: The system integrated an approach based on sensory function interaction, called the clinical test of sensory interaction with balance (CTSIB). The piezo-resistive force mat was fabricated, and a Stability Index prediction algorithm was developed and applied using the center of pressure (CoP) variables. The Stability Index prediction algorithm derived a CoP variable for 103 elderly people by Nintendo Wii Balance Board (WBB) to predict the Stability Index of the Balance System (Biodex SD). And, the accuracy was confirmed through the correlation between the real and predicted value. Results: As a result of testing with the test-set, the linear regression model confirmed that the r value ranged between 0.943 to 0.983. To confirm the similarity between the WBB and flexible force mat, each measured CoP value was i...

Forward and inverse dynamic study during pedaling: Comparison between the young and the elderly

Technology and health care : official journal of the European Society for Engineering and Medicine, Jan 29, 2016

As it is not easy to investigate various variables that affect exercise efficacies and cause inju... more As it is not easy to investigate various variables that affect exercise efficacies and cause injuries while pedaling in the actual experiment, especially for the elderly, the musculoskeletal model simulation with a comparison of measured electromyography (EMG) data could be used to minimize experimental trials. The measured EMG data were compared with the muscle activities from the musculoskeletal model through forward (FD) and inverse dynamic (ID) analysis. EMG was measured from eight young adult (20's) and eight elderly (70's) in three minutes pedaling with a constant load and 40 revolutions per minute (RPM) cadence. The muscles used for the analysis were the VastusLateralis, Tibialis Anterior, Bicep Femoris, and Gastrocnemius Medial. Pearson's correlation coefficients of the muscle activity patterns, on-off set, and peak timing at the maximum muscle activity were calculated and compared. BIKE3D and GaitLowerExtremity model were used for the FD and ID simulation. There...

Differences In Stress And Total Deformation Due To Muscle Attachment To The Femur

To achieve accurate and precise results of finite element analysis (FEA) of bones, it is importan... more To achieve accurate and precise results of finite element analysis (FEA) of bones, it is important to represent the load/boundary conditions as identical as possible to the human body such as the bone properties, the type and force of the muscles, the contact force of the joints, and the location of the muscle attachment. In this study, the difference in the Von-Mises stress and the total deformation was compared by classifying them into Case 1, which shows the actual anatomical form of the muscle attached to the femur when the same muscle force was applied, and Case 2, which gives a simplified representation of the attached location. An inverse dynamical musculoskeletal model was simulated using data from an actual walking experiment to complement the accuracy of the muscular force, the input value of FEA. The FEA method using the results of the muscular force that were calculated through the simulation showed that the maximum Von-Mises stress and the maximum total deformation in C...

A Study On Human Musculoskeletal Model For Cycle Fitting: Comparison With Emg

It is difficult to study the effect of various variables on<br> cycle fitting through actua... more It is difficult to study the effect of various variables on<br> cycle fitting through actual experiment. To overcome such difficulty,<br> the forward dynamics of a musculoskeletal model was applied to cycle<br> fitting in this study. The measured EMG data weres compared with the<br> muscle activities of the musculoskeletal model through forward<br> dynamics. EMG data were measured from five cyclists who do not<br> have musculoskeletal diseases during three minutes pedaling with a<br> constant load (150 W) and cadence (90 RPM). The muscles used for<br> the analysis were the Vastus Lateralis (VL), Tibialis Anterior (TA),<br> Bicep Femoris (BF), and Gastrocnemius Medial (GM). Person's<br> correlation coefficients of the muscle activity patterns, the peak timing<br> of the maximum muscle activities, and the total muscle activities were<br> calculated and compared. BIKE3D model of AnyBody (Anybodytech,<br> ...