• The Journal of Korean Physical Therapy
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• v.27 no.2
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• pp.89-95
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• 2015

Purpose: The purpose of this study is to determine the effects of visual information on movement time and each angular velocity of trunk and lower extremity joints while healthy adults are in sitting and squat motion. Methods: Participants consisted of 20 healthy male and female adults; movement time and each angular velocity of trunk, pelvis, hip, knee and ankle of sitting and squat motion according to common vision, visual task and visual block were analyzed using a three dimensional motion analysis system. Results: Each angular velocity of the trunk, pelvis, hip, knee and ankle in phase 2 of the sitting showed significant difference according to the types of visual information (p<0.05). Movement time and each angular velocity of pelvis and hip in phase 2 of squat motion showed significant difference according to the types of visual information (p<0.05). According to the common vision, each angular velocity of knee and ankle in phase 1 was significantly fast in sitting (p<0.05). According to the common vision, each angular velocity of trunk, pelvis, hip, knee, and ankle in phase 2 was significantly fast in sitting (p<0.05). Conclusion: Visual information affects the angular velocity of the motion in a simple action such as sitting, and that in more complicated squat motion affects both the angular velocity and the movement time. In addition, according to the common vision, visual task and visual block, as angular velocities of all joints were faster in sitting than squat motion.

• The Journal of Korean Physical Therapy
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• v.34 no.2
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• pp.63-67
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• 2022

Purpose: The purpose of this study was to investigate the effect of assistance tools such as gym balls, wedges, and straps on lower extremity muscle activity and the increase in the range of motion made possible by the use of these tools. The subjects were divided into two groups: a group capable of deep-squatting (PS) and the second finding it impossible or having difficulty in performing such squats (IS). Methods: Twenty-three subjects participated in this study. Surface electromyography was used to measure the muscle activation of the rectus femoris (RF), vastus medialis (VM), and tibialis anterior (TA) muscles during deep squats, normal squats (NS), gym ball squats (GS), wedge squats (WS), and strap squats (SS). A motion analysis system was used to measure the range of motion of the knee joint during each of these exercises. Results: There was a significant difference in the RF muscle activity between the possible squat (PS) and the impossible squat (IS) groups in the GS, and there were significant differences in the RF and TA muscle activity between the groups in the WS. Both the PS group and the IS group showed a significant difference in the TA muscle activity depending on the tool used. There were also significant differences in the range of motion of the knee joints between the intervention methods using NS and those using the tools. Conclusion: In both groups, the muscle activity of the TA muscles was lower when GS, WS, and SS were performed compared to NS. In addition, compared to NS, the range of motion of the knee joint increased when the three tools were used. This study shows that the activity of the RF, VM, and TA muscles decreased and the range of motion of the knee joint increased during deep squats for both the PS and IS groups when tools were used.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.355-361
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• 2020

The squat is an exercise that can effectively improve the muscle strength of the lower body, which can be performed in a variety of places without restrictions on places including homes. However, injuries due to incorrect motion or excessive angles are frequently occurring. In this study, we developed a single sensor-based squat angle measurement system that can inform the squat angle according to the correct motion during the squat exercise. The sensor module, including the acceleration sensor and the gyro sensor, is attached to the user's thigh. The squat angle was calculated using the complementary filter complementing the pros and cons of acceleration and gyro sensor. It was found that the calculated squat angle showed the proper correlation compared to the squat angle measured by a goniometer, and the influence of the coefficient of the complementary filter on the accuracy was evaluated.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.755-761
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• 2020

The purpose of this study was to investigate the effects of balance board and whole-body vibration stimulator application on body muscle activities during static squat motion. Twenty adult males(age, 21.90±0.36 years; height, 174.30±1.09 cm; body mass, 66.50±1.00 kg; and BMI, 21.90±0.31 kg/㎡) were participated in this study as subjects. Three types' static squat motions were performed(basic static squat motion, BSSM; static squat motion with balance board, SSBB; static squat motion with whole-body vibration stimulator, SSVS). We measured the right side's body muscle activities of the rectus abdominis(RA), internal oblique(IO), external oblique(EO), rectus femoris(RF), vastus lateralis(VL), and vastus medialis(VM). The research findings were as follows. There was a significant higher RA, IO, and EO muscle activity of SSBB and SSVS(p=.001, p=.004, p=.000). And RF, VL, and VM muscle activities were greatest during SSVS(p=.000). These findings are expected to serve as references for static squat motion applications in training programs for body muscle strengthening.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.501-502
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.689-690
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• 2007

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.691-701
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• 2017

The barbell squat is a fundamental physical exercise for strengthening the lower body and core muscles. It is an integral part of training and conditioning programs in sports, rehabilitation, and fitness. In this paper, we proposed a virtual test framework for squat exercises using a Smith machine to simulate joint torques and muscle forces, based on an integrated product-human model and motion synthesis algorithms. We built a muscular skeletal human model with boundary conditions modeling the interactions between the human body and a machine or the ground. To validate the model, EMG, external forces, and squat motions were captured through physical experiments by varying the foot position. A regression-based motion synthesis algorithm was developed based on the captured squat motions to generate a new motion for a given foot position. The proposed approach is expected to reduce the need for physical experiments in the development of training programs.

• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.183-189
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• 2023

The propose of this study was to investigate the effects of squat exercise using a reformer on muscle strength, range of motion, and gait in hip joint replacement patients. This study was conducted on 20 patients hospitalized at a rehabilitation hospital in G City. As an intervention method, the experimental group performed squat exercises using a reformer, and the control group performed squat exercises, 7 times a week for 2 weeks. In the within-group comparison of the reformer group, there was a significant difference in hip flexion, extension, and abduction strength (p<0.05). There were significant differences within the group in the range of motion of hip extension and abduction and gait in the Reformer group (p<0.05). In comparison between groups, significant differences occurred in hip extension strength, hip extension, abduction range of motion, and gait (p<0.05).

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.363-367
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• 2009

The ship maneuverability is changed by the effects of the bank cushion and the squat in the restricted water area. It is difficult to test the ship maneuverability by the real ship in the restricted water area because of ship's safety. In this study, a numerical model ship was used to simulate the ship's motion and to get information about the bank cushion and the squat in the restricted water area. The less apart from the quay the ship ran, the more ship's heading changed. The greatest change of ship's heading was $22.37^{\circ}$ when a ratio of the length between ship and quay to ship's breadh(=D/B) was 0.2. The squat of the ship was greater in shallower water and at faster speed. The greatest squat was 0.29m when a ratio of water depth to ship's draft(H/d) was 1.25 and ship's speed was 8 knots, the reduced speed was found to be the most important factor in the shallow water area for safety of the ship.

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.107-114
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• 2011

Closed kinematic chain exercises such as squatting have been widely indicated for knee rehabilitation in patients with patellofemoral disorders such as osteoarthritis and patellofemoral pain. Patellofemoral disorders are thought to be associated with abnormal patellar kinematics. In addition, the Q-angle may be undervalued in patients with patellofemoral pain and a laterally displaced patella. The purpose of this study was to assess patellar kinematics and the Q-angle during double-leg semi-squat and wall-slide semi-squat exercises. In this study, 28 asymptomatic subjects(16 male, 12 female) were assessed. Patellar tilt, patellar spin, and Q-angle were recorded using a motion analysis system during double-leg semi-squat and wall-slide semi-squat exercises. The Q-angle and patellar tilt were significantly increased, whereas patellar spin was significantly decreased, at $45^{\circ}$ of knee flexion compared with $0^{\circ}$. No differences were observed for the Q-angle, patellar tilt, and patellar spin during double-leg semi-squat and wall-slide semi-squat exercises. However, a significant interaction was observed between squat type and knee angle for patellar spin. We found that the patella is laterally tilted during semi-squat exercises and that there was no difference in patellar tracking between knee flexion during double-leg semi-squat and wall-slide semi-squat exercises.