• The Journal of Korean Physical Therapy
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• v.16 no.2
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• pp.22-32
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• 2004

The purpose of this study was to examine the effect of ankle-foot orthosis and lumbosacral orthosis on movement patterns used to rise from the supine position to erect stance. Thirty-two healthy adults participated. Subjects were videotaped while rising from a supine position on a floor mat. Each subject performed 10 trials each of three condition;general condition, right ankle-foot orthosis, lumbosacral orthosis. subjects rose most commonly using a symmetrical push pattern of the upper extremities, a symmetrical squat pattern in the lower extremities, a symmetrical in the trunk under each of three conditions. Changes in the incidence of movement patterns occurred in lower extremities of the ankle-foot orthosis and lumbosacral orthosis condition and trunk of the ankle-foot orthosis condition. From a dynamic pattern theory perspective, ankle motion is a control variable for the supine position to erect standing movement.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1709-1712
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• 2008

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 14mm 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, 15kg, 20kg 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.

• Proceedings of the ESK Conference
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• 1995.10a
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• pp.156-163
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• 1995

An experimental protocol was developed and tested in this study in order to quantify the motor control capability of the trunk movement for both healthy subjects and low-back pain (LBP) patients. Information processing capacity (bits/second) (Fitts, 1954) and dynamic motor perfor- mance such as flexion/extension velocity and acceleration were measured as motor control parameters under the controlled range of motion (ROM). In this study, the original experimental propocol (Kim et al., 1993, 1994) was re-designed to reduce the length of the test via a series of statistical analyses for clinical application. The accuracy of the shortened protocol was statistically examined and indicated no difference conpared to the original protocol in terms of evaluating information processing capacity. This protocol was also tested among ten healthy subjects and ten LBP patients for validation purpose. The results showed that the information processing capacity was not significantly diffenent between two groups due to the large variation although there was an apparent mean difference. Average movement time showed a significant increase in LBP patients com- pared to healthy subjects. In conclusion, it was found that the new short experimental protocol could quantify the motor control capability of neuromuscular system of the trunk and also showed the applicability to patient population.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3092-3094
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• 1999

This paper deals with the gait generation of Biped Walking Robot (IWR-III) to have a continuous walking pattern like human. For this, trajectory planning with the consideration of kick action is done in each walking step, and the coordinate transformation is done for simplifying the kinematics. The trunk moves continuously for all walking time and moves toward Z-axis. Balancing motion is acquired by FDM(Finite Difference Method) during the walking. By combining 4-types of pre-defined steps, multi-step walking is done. Using numerical simulator, dynamic analysis and system stability is confirmed. Walking motion is visualized by 3D-Graphic simulator. As a result, the motion of balancing joints can be reduced by the trunk ahead effect during kick action, and impactless smooth walking is implemented by the experiment.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.97-104
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• 2014

Automobile trunk latches enable trunks to be opened and closed by a latch mechanism, which can be selectively positioned between a locked condition and an open condition. To maintain structural and electronic performance of the trunk latch, the latch needs to endure impact load that occurs in its open and close motion, and a dynamic mechanism needs to be electronically controled by a contact switch connected with a small DC motor. A base plate, which is the most important component relating to the structural safety, commonly uses a high stiffness material SAPH440-P with high manufacturing cost. In this paper, through structural analysis and optimization, production cost is significantly reduced by replacing SAPH440-P used in some region of the base plate with engineering plastic PBT GF 20%. The optimized contact switch reduces difference between distributed pressures of its two legs, which leads to improve the electronic performance of the trunk latch.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.765-768
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• 2000

Linearization of the biped dynamic equations and design of linear controller for the linearized equations are studied in this paper. The biped robot with inverted pendulum type trunk, used to stabilize the dynamic balancing of the biped robot during dynamic walking period, is modelled with 14 DOF and simulated. Despite of well defined linear control theories so far, the linear control methods was limited to the applications for a walking robot, because they have been inherently strong nonlinear properties, such as a modeling parameter uncertainties, external forces as noise, inertial and Coriolis terms by three dimensional modeling and so on. To linearize the nonlinear equations of motion of biped robot on MIMO and time varying linear equations of motion, 1st order Taylor series is used to formulate the linear equation. And a 2nd order numerical perturbation method Is used to approximate partial differential equations. Using the linearized equations of motion, a linear controller is designed by pole placement method with feed forward compensation. Using the obtained linearized equations and linear controller, the continuous walking simulation is performed.

• International Journal of Control, Automation, and Systems
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• v.4 no.3
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• pp.325-332
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• 2006

The dynamic responses of human standing postural control were investigated when subjects were exposed to long-term horizontal vibration. It was hypothesized that the motion of standing posture complexity mainly occurs in the mid-sagittal plane. The motor-driven support platform was designed as a source of vibration. The AC Servo-controlled motors produced anterior/posterior (AP) motion. The platform acceleration and the trunk angular velocity were used as the input and the output of the system, respectively. A method was proposed to identify the complexity of the standing posture dynamics. That is, during AP platform motion, the subject's knee, hip and neck were tightly constrained by fixing assembly, so the lower extremity, trunk and head of the subject's body were individually immovable. Through this method, it was assumed that the ankle joint rotation mainly contributed to maintaining their body balance. Four subjects took part in this study. During the experiment, the random vibration was generated at a magnitude of $0.44m/s^2$, and the duration of each trial was 40 seconds. Measured data were estimated by the coherence function and the frequency response function for analyzing the dynamic behavior of standing control over a frequency range from 0.2 to 3 Hz. Significant coherence values were found above 0.5 Hz. The estimation of frequency response function revealed the dominant resonance frequencies between 0.60 Hz and 0.68 Hz. On the basis of our results illustrated here, the linear model of standing postural control was further concluded.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.552-554
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• 1998

This paper deals with the gait generation of IWR-III using a kick action to have a walking pattern like human. For this, trajectory planning with the consideration of kick action is done in each walking step, and the coordinate transformation is done for simplifying the kinematics. Balancing motion is analyzed by FDM during the walking, By combining 4-types of pre-defined steps, multi-step walking is done. Using numerical simulator, dynamic analysis, ZMP analysis and system stability is confirmed. Walking motion is visualized by 3D- graphic simulator. As a result, trunk ahead motion effect and impactless smooth walking is implemented by experiment. Finally walking with kick action is implemented the IWR-III system.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.905-913
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• 2018

The purpose of this study is to investigate the difference of muscle activity according to application of a foam roller during pilates. The 8 male subjects were selected and quadruped position, bridge, and core control movement of pilates were randomly assigned to 9 movements on a static mat motion, static foam-roller motion, and dynamic foam-roller actions. This program was conducted once at intervals of 1 week. The muscle activity of erector spinae, rectus abdominis, external oblique, gluteus medius, rectus femoris, and biceps femoris were measured and the collected data was analyzed by one-way ANOVA. First, in the quadruped, the rectus abdominis and external oblique, rectus femoris of the dynamic foam-roller actions showed higher muscle activity than the static mat motion and the static foam-roller motion(p <.001), gluteus medius muscle activity was also significantly higher (p <.05). biceps femoris were significantly higher in static foam-roller motions than in static mat-motion and dynamic foam-roller actions(p <.05). Second, biceps femoris muscle activity was highest in dynamic foam-roller actions than static mat-motion and static foam-roller motions during bridge(p <.001). Third, in the sitting core control, the rectus abdominis and gluteus medius of the dynamic foam-roller actions showed higher muscle activity than the static mat motion and the static foam-roller motion(p <.001). and activity of erector spinae muscle was also significantly higher (p <.01). external oblique were significantly higher in static mat-motion than in static foam-roller motions and dynamic foam-roller actions(p <.05). Considering the muscle activity during pilates exercise, it would be more effective to apply the method and difficulty.

• Journal of the Ergonomics Society of Korea
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• v.14 no.2
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• pp.1-14
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• 1995

Neuromuscular difference between normal subjects and low-back pain patients has been identified in terms of neural excitation signal measured by Electromyography (EMG) under the dynamic flexion/extension trunk motion. Ten healthy subjects and ten low-back pain patients were recruited for this study. New parameters and normalization technique were introduced to quantify the muscle excitation pattern among the flexor-extensor pairs of muscles : rectus abdominis (RA)-erector spinae (ES at L1 and L5 level), external oblique (EO)-internal oblique (IO), rectus femoris (quadricep : QUD)-biceps femoris( hamstring : HAM), and tibialis anterior (TA)-gastrocnemius (GAS). Results indicated that the temporal EMG pattern such as peak timing difference between the hip flexor (QUD) and extensor (HAM) and the duration of coexcitation between ES at L5 and RA muscle pairs showed a statistically significant difference between normal subjects and low-back pain patients. Improtantly, this study presented a new technique to identify the dynamic muscle excitation pattern that canb be least affected by EMG-length-velocity relationship. Further study can performed to validate this method for clinical application to quantitatively identify the low-back pain patients in the future.