Quick picking and heavy lifting are the most common problems in current workplaces. They can cause lumbar muscle damage. The operator then must spend energy, time, and money for recovery or rehabilitation. To solve this problem, we developed a passive-type assistive suit using air mesh material, elastic band, and wire. To determine the strength support effect of the passive-type assistive suit, electromyography (EMG) was performed for eight muscles and the maximum voluntary contraction (MVC) was analyzed when lifting weights of 0%, 15%, and 30% of the subject’s weight in a Semisquat motion. Results showed that MVC increased as the weight of the heavy object increased. However, its increase was not proportional to the decrease in MVC according to the presence or absence of assistive suits or the weight of the heavy object. The highest MVC was observed for the erector spinae muscle under all conditions. The greatest decrease in MVC according to working clothes was measured for the vastus lateralis muscle (lifting: 17.7±2.95%, lowering: 18.3±0.55%). These results show that lifting work performed while wearing a passive-type assistive suit using wires and elastic bands is effective in assisting muscle activity.
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EMG and Usability Assessment of Adjustable Stiffness Passive Waist-Assist Exoskeletons for Construction Workers Jung Sun Kang, Bo Ra Jeong, Eung-Pyo Hong, Bok Man Lim, Byung June Choi, Youn Baek Lee, Yun Hee Chang International Journal of Precision Engineering and Manufacturing.2025; 26(1): 227. CrossRef
The purpose of the study was to evaluate the lumbar mobility and flexibility by the vertical vibration stimulation. The subjects were 21 young adults were divided into vibration group (n = 7) that applied 30 Hz vibration stimulation to the lumbar, foam roller group (n = 7) that relaxes the lumbar muscles with a foam roller, and good morning exercise group (n = 7) that stimulates the lumbar spine with the good morning exercise. The muscle strength, EMG and the sit & reach test were measured, to evaluate the lumbar mobility and flexibility before and after exercise intervention in each group. Results showed increasing in the vibrating group in muscle strength and EMG, and the good morning group and the vibrating group in the Sit & Reach test. This can be developed as a new alternative to exercise therapy for spine rehabilitation.
Many of the workers are exposed to work that burdens the musculoskeletal system, and musculoskeletal diseases, such as low back pain, are increasing every year. Various muscle support systems, such as wearable robots, have been developed to prevent musculoskeletal diseases at industrial sites, but the system is bulky. Therefore, the total weight is high, it is inconvenient to wear, and the wearer cannot freely perform the activities when power is not supplied. In this paper, in order to compensate for the shortcomings of the hard-type wearable robot system, a soft-type wearable suit using an elastic band was manufactured so that it is light and portable, as it does not require an actuator. The experiment was conducted to verify the effect of muscle strength assistance through an experiment (Measurement of Maximum Waist Torque and Measurement of the Approximate Dose) on the effect of the soft wearable suit. In addition, by making two different types of elastic bands in the wearable suit, it was possible to classify the more effective types for the waist and lower extremities according to the elasticity by comparing the muscle strength assisting effect according to the elastic band.
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EMG and Usability Assessment of Adjustable Stiffness Passive Waist-Assist Exoskeletons for Construction Workers Jung Sun Kang, Bo Ra Jeong, Eung-Pyo Hong, Bok Man Lim, Byung June Choi, Youn Baek Lee, Yun Hee Chang International Journal of Precision Engineering and Manufacturing.2025; 26(1): 227. CrossRef
Development of lifting-assistive passive functional pants for construction works Jin Zhi Chen, Jeong Eun Yoon, Zi Ying Liu, Sung Kyu Lee, Sumin Helen Koo Textile Research Journal.2025;[Epub] CrossRef
Effects of the Wearable Assistive Suit on Muscle Activity during Lifting Tasks Kwang Hee Lee, Chul Un Hong, Mi Yu, Tae Kyu Kwon Journal of the Korean Society for Precision Engineering.2024; 41(1): 47. CrossRef
Design development and evaluation of arm movement-assistive suits for lifting and movement for industrial workers considering wearability Jiwon Chung, Jung Eun Yoon, Soah Park, Hyunbin Won, Suhyun Ha, Sumin Helen Koo International Journal of Industrial Ergonomics.2024; 103: 103616. CrossRef
Enhancing wearability: designing wearable suit platforms for industrial workers Jiwon Chung, Hyunbin Won, Hannah Lee, Soah Park, Hyewon Ahn, Suhyun Pyeon, Jeong Eun Yoon, Sumin Koo International Journal of Clothing Science and Technology.2024; 36(3): 526. CrossRef
The purpose of this study was to develop and verify the smart insole based FSR sensor for measurement and improvement of the muscle strength imbalance. We recruited 15 subjects with muscle strength difference over 20% and 15 subjects with muscle strength balance below 10%. We developed the human body load insole and integrated modules using FSR sensor. Subjects walked for 5 minutes at a slope of 0% and a speed of 3 km / h on a treadmill with a smart insole. We measured the real-time muscle activity and foot pressure according to the muscle strength imbalance during gait. FSR data of the developed smart insole showed that the insole had similar accuracy and efficacy as muscle activity and foot pressure. This is the interval in which the muscle imbalance shifts from the stance phase to the load reaction, and the weight support is the largest, and the center of gravity of the human body passes over the whole foot, which is considered to cause the greatest imbalance. This suggests that there is a direct or indirect correlation between muscle strength imbalance of the lower limb and the imbalance of the body weight distribution during gait.
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Design and manufacturing of a smart insole Seung Joo Lee, Chae Young Park, In Hwan Lee Sensors and Actuators A: Physical.2026; 397: 117225. CrossRef
Functional evaluation of air insoles and methodology for determining the optimal thickness according to weight group Seungnam Min, Murali Subramaniyam, Heeran Lee International Journal of Industrial Ergonomics.2024; 101: 103582. CrossRef
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STUDY ON VISION-BASED MULTIDIRECTIONAL POSTURE AND MOTION ANALYSIS SYSTEM DEVELOPMENT WOO SUK CHONG, MI YEON SHIN, CHANG HO YU Journal of Mechanics in Medicine and Biology.2019; 19(08): 1940059. CrossRef
This study was undertaken to develop a bed-type cycling system of lower limbs for rehabilitation. This system consists of two modes of cycling: active and passive. Different velocity and loads are provided for improving the muscle function recovery and increasing the muscular strength. To analyze the muscle activity pattern, we measured muscular activity of lower limbs in the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), medial gastrocnemius (MG), and soleus (SOL), while cycling in the supine position, and based on the pedaling direction. A total of 18 young and 23 elderly, healthy subjects participated in this study. Muscle activity of MG muscles was significantly different in the two age groups. This study could provide the reference data to develop cycling exercises for lower limbs during rehabilitation of the elderly patients.
Weight bearing is effective during rehabilitation of gait, in the elderly and disabled people. Various training devices using weight bearing function were developed along with treadmill walking; however, no device has been developed in conjunction to walking on the ground. Here, we designed a rail type frame of a gait rehabilitation system for body-weight support (BWS) function, and analyzed its mechanical safety in the static weight bearing condition of a vertical axis. Computational simulations were performed to analyze structure of the driving parts, which are connected with a rail and driving rollers and the lower plate of the BWS. Structural analyses showed the drivers and BWS were safe, when simulated at 135kg weight under static conditions. Thus, this rail type rehabilitation system can be used for gait training of the elderly and disabled.
In this paper, capture motion and visual information from a virtual reality luge simulator to analyze muscular activity in the lower limbs. The Luge Simulator consists of a motion platform with a pneumatic module for weight distribution. We recruited luge athletes and healthy subjects and made real-time surface EMG measurements to estimate the muscular activity in the lower limbs according to the motion protocol of a simulator, and a test was conducted for each subject. The results indicated that the rectus femoris had the highest muscular activity according to the level of the slope and velocity of the luge. The soleus muscle showed a high level of activity during a turn in the luge according to the direction. We found that the development of a virtual reality sports simulator based on physical reaction results could bring positive effects to optimize reality and human cenesthesia.
The purpose of this study was to verify the effect on improvement of muscle strength unbalance according to load deviation protocol during whole body vibration exercise. Seventeen female volunteers (age 22±3 years, height 160±4.9 cm, weight 49±.8 kg) participated in this experiment. The subjects performed squat exercise in WBV platform. Exercise were performed five set a day including 15 time a set, three days a week, and during 4 weeks. Vibration stimulus was 25Hz as frequency and intensity was dominant leg 1mm and non-dominant leg 4mm. The results in WBV group showed that the differences of peak torque in 16% were getting decreasing significantly after 4 weeks from 16.2% to 5.2%. This result means that WBV with load deviation protocol could provide muscle strength exercise for muscle strength balance. Our study found out that WBV of load deviation protocol could provide muscle strength exercise for improving muscle imbalance.
This study investigated the effect of whole-body vibration on muscle function and muscular reaction in the knee joint. We recruited thirty healthy subjects and divided them into a training group, who experienced whole-body vibration, and a control group, who did not. The training group performed whole-body vibration exercises for 30 min per day, 3 days a week, for 8 weeks. We measured knee joint torque to estimate muscle strength and reaction, using BIODEX System 3. Knee joint peak torque and total work performed increased significantly in the training group, and muscle acceleration time decreased. These results suggest that stimulation by whole-body vibration can improve muscle strength and reaction by improving muscle tone and increasing blood temperature and flow speed in muscular fiber. Our results also indicate that 4 weeks of exercise with whole-body vibration is required to improve the reaction response, and six weeks to improve strength.
The Interest in disease prevention and rehabilitation is increasing depending on increase of patients with spinal. This is being developed using the spine stabilization device is being studied. So far studies have only evaluated the effect on trunk stabilization exercises but analysis of human movement patterns for active movement and passive movement did not. We assessed the muscle activity of trunk and leg muscle during passive and active tilt mode on eight tilt directions at tilt angle of 30° using 3-D dynamic postural balance training system. We performed experimental study on the muscular activities of trunk muscle about rectus abdominis, external obliques, latissimus dorsi, erector spinae, and leg muscle about rectus femoris, Biceps femoris, Tibialis Anterior, gastrocnemius. As a result, muscle activation was different depending on the direction of movement and pattern. The results indicate that various patterns of spinal stabilization exercise system could be applied to an effective training of chronic low back pain patients.
In this study, we proposed the most efficient driving posture based on the analysis of quantitative muscular strength and fatigue degree according to posture. Since driving include complicated actions required by a variety of ability and cause by extremes concentration or strain, drivers tend to feel tired easily. However, drivers can"t recognize the fatigue degree by themselves. Moreover, the method for measuring the quantitative fatigue degree exactly is quite difficult to be secured. 9 professional bus drivers were participated. We analyzed the quantitative legs" muscular strength when operating each pedal. And then we also analyzed the muscular strength and muscular fatigue degree according to driving pattern during bus driving. Therefore, we suggested the most efficient driving posture.
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.
This study is to compare muscle strength between isotonic exercise and isotonic & isokinetic exercise. Participants are 12-man and 10-woman whom they are healthy without medical history in shoulder, elbow and lumbar joint. We performed experiment total 4-weeks that exercise 3-days a week each exercise pattern. We measured shoulder, elbow and lumbar joint torque with BIODEX and circumference of muscle in upper arms once a week. The result showed that isotonic & isokinetic exercise pattern significantly more improved joint torque in shoulder, elbow, lumbar than isotonic exercise pattern. Because that isotonic & isokinetic exercise pattern supplied muscle strengthen and caused muscle contraction. This exercise pattern can be used new exercise training method for major athlete and normal people. Also this pattern can be used rehabilitation treatment.
We investigated an early rehabilitation training system that increase the intensity of patient rehabilitation training to shorten the time it takes for patients to progress to a secondary rehabilitation training stage by allowing patients incapable of self-ambulation. It consisted of tilting bed, unstable platform using strong springs and training program for lower limb rehabilitation. We performed experimental study on the muscular activities of tibialis anterior(TA), soleus(SO), gastrocnemius(GA) in the lower extremities during training of straight line, circle, quardrangle pattern during tilting angle of 30°, 60°. The muscle activities were higher during tilting angle of 30° than 60°. In straight line pattern, the muscle activities were higher by SO, GA and TA during medio-lateral direction, however, by TA, SO and GA during anterio-posterior direction. In circle and quardrangle pattern, the muscle activities were higher by TA, SO and GA during clockwise and counterclockwise direction. The results indicate that the early rehabilitation training system could be applied to improve the lower extremity muscular strength for elderly and patients, especially, stroke.
In this paper, we estimated the effects of different color stimulation on the cognitive function of human quantitatively. For the stimulations we used color lights with 6 color filters such as red, yellow, green, blue, violet and white. The experiment was performed in a soundproof chamber. 50 young male and female subjects were participated in the experiment. To find the appropriate color cognitive function, the endogenous visuospatial attention task(EVAT) and one back working memory task(OWMT) were performed. The reaction time and accuracy degree were measured. The results showed that the reaction time of EVAT was the fastest and the accuracy degree of attention task was the highest in green environment. The reaction time of OWMT was the fastest in yellow and the accuracy degree of memory task was the highest in blue. For physiological parameters, we measured electrocardiogram(ECG) and HRV spectrum analysis, HF/LF color environment. These results can be used as an indicator in the design of color environment and clinical applications.
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