• Journal of Korean Academy of Medicine & Therapy Science
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• v.10 no.2
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• pp.21-30
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• 2018

Objective: The purpose of this study was to investigate questions and instructions for internal feedback effects on functional recovery and task performance while chronic stroke patients practised task-specific training. Method: Twenty-four chronic stroke patients were randomly divided into two groups; when patients performed same tasks, one was treated using questions and the other using instructions for internal feedback Both lasted 30 minutes, 5 times a week for 8 weeks. Outcome measures included Erasmus MC Modifications to the Nottingham Sensory Assessment (EmNSA), Measurement Properties of the Motor Evaluation Scale for Upper Extremity in Stroke patients (MESUPES), Chedoke Arm and Hand Activity Inventory (CAHAI), Korean version of Modified Barthel Index (K-MBI). Results: There were no significant differences between the two groups in EmNSA and K-MBI(p>.05). But, in MESUPES and CAHAI, there was significant difference between the two groups(p<.05). Conclusion: In this study, questions for internal feedback during task-specific training are more effective in improving upper extremity motor function and task performance than instructions for internal feedback.

• 전기의세계
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• v.13 no.4
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• pp.25-29
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• 1964

This paper shows that higher amplification can be achieved by applying load current on the internal feedback winding of the magnetic amplifier under test. Since the magnetic flux of the control winding and internal feedback winding saturate the core more fully, the permeability tends to zero and load current increases to the value more than that of ordinary magnetic amplifier without feedback.

• Bulletin of the Korean Mathematical Society
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• v.54 no.4
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• pp.1457-1470
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• 2017

In this paper, we consider the stabilization of the viscoelastic wave equation with variable coefficients in a bounded domain with smooth boundary, subject to linear dissipative internal feedback with a delay. Our stabilization result is mainly based on the use of the Riemannian geometry methods and Lyapunov functional techniques.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.3
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• pp.107-113
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• 2021

PURPOSE: Selective strengthening of the transverse abdominis muscle (TrA) during abdominal hollowing makes an important contribution to the stability and control of the spine. This study examined the effects of abdominal hollowing exercise (AHE) according to the visual feedback method on the external oblique, internal oblique, and transverse abdominis muscles. METHODS: Twenty healthy subjects were assigned randomly to an AHE with visual feedback from real-time ultrasound image (group A, n = 10), AHE with visual feedback with pressure biofeedback unit (group B, n = 10). Both groups underwent 20 min of AHE with visual feedback once daily, five days/week for two weeks. The changes in the muscle thickness of the TrA, internal oblique abdominal muscle (IO), and external oblique abdominal muscle (EO) were measured by ultrasonography. RESULTS: The thickness of TrA was changed significantly in both groups (p < .05). However, the lowest minimal detectable changes were achieved in Group A. The thickness of the IO and EO muscles in group A was changed significantly, but there were no significant changes in group B. CONCLUSION: Both visual feedback methods were effective for strengthening the TrA muscles selectively. Nevertheless, AHE with visual feedback using real-time ultrasound images may be more useful in trA muscle contraction.

• Physical Therapy Rehabilitation Science
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• v.1 no.1
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• pp.13-16
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• 2012

Objective: Electroencephalogram (EGG)-feedback is a training procedure aimed at altering brain activity, and is used as a treatment for disorders like attention. The purpose of this study was to determine the effects of external focus of attention by EGG-feedback on balance in young adults. Design: Cross-sectional study. Methods: Subject were students in Sahmyook University. Fifty young adults in their twenties and thirties. Subjects were performed both with and without external focus of attention by EEG-feedback on the posture of standing and tandem standing. Participants were educated effort to maintain static posture when they were under internal focus of attention. Good Balance System was used for measurement of postural consistency upon the following force platforms. Results: Body sway decreased significantly both normal standing and tandem standing with external focus of attention by EEG-feedback (p<0.05). Conclusions: The results demonstrate that the benefits of an external attentional focus are generalizable to young adults. The external focus of attention outperformed the internal focus of attention on the postural balance (p<0.05). It is showed that external focus of attention significant effects on balance by revoked automatic postural control of movement. Furthermore balance might be improved by training with an external focus. Further study is required to develop for training as a method of preventing fall in elderly peoples.

• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.40-41
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• 1993

생물 ㅏ반응기의 생산성을 높이기 위해서는 반응기내의 미생물 농도를 높이는 것이 필요하다. 미생물 농도를 높이기 위한 한 방법으로써 막을 이용한 미생물 재순환에 대한 많은 연구가 수행되어 왔다. 이러한 연구들은 발효조 밖에서 막을 이용하여 미생물을 분리하여 다시 발효조 내로 순환시키는 방법이 주를 이루어 왔으나 이들은 공정이 복잡하고 고분자 합성막을 이용한 경우 고온 멸균의 어려움이 있는등 산업화하는데 여러가지 문제점을 가지고 있었다.

• Proceedings of the Membrane Society of Korea Conference
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• 1991.04a
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• pp.19-22
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• 1991

생물 반응기내에 미생물 농도를 높이기 위한 한 방법으로써 막을 이용한 미생물 재순환에 대한 연구가 이루어져 왔다. 이러한 연구들은 발효조 밖에서 막을 이용하여 미생물을 분리하여 다시 발효조 내로 순환시키는 방법이 주를 이루었으나 이들은 공정이 복잡하고 고분자 합성막을 이용한 경우 고온 멸균의 어려움 등 산업화하는데 여러가지 문제점을 가지고 있었다.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.12
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• pp.1077-1082
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• 2005

In this paper, it is proposed that the method for constituting pressure control system controlled by Direct Drive Valve (DDV). The DDV has a pressure-feedback-loop itself. It can eliminate non-linearity and uncertainty oi hydraulic system such as uncertain discharge coefficient and change of bulk-modulus. However, the internal feedback-loop can not compensate them perfectly. And fixed gain of the DDV's internal feedback-loop is not proper to apply it through wide pressure range. The steady state error and nonlinear characteristic of transient behaviour is observed in the experiment. So another controller is needed for the desirable performance of the system. To compose the controller, the pressure control system controlled by DDV is modeled mathematically and the parameters of the model are identified using signal-compression method. Then sliding mode controller is designed based on mathematical model. Desirable performance of the pressure control system controlled by DDV is obtained.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.515-525
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• 2008

In this paper, the problem of delay-dependent stabilization for singular systems with multiple internal and external incommensurate constant point delays is investigated. The condition when a singular system subject to point delays is regular independent of time delays is given and it can be easily test with numerical or algebraic methods. Based on Lyapunov-Krasovskii functional approach and the descriptor integral-inequality lemma, a sufficient condition for delay-dependent stability is obtained. The main idea is to design multiple memoryless state feedback control laws such that the resulting closed-loop system is regular independent of time delays, impulse free, and asymptotically stable via solving a strict linear matrix inequality (LMI) problem. An explicit expression for the desired memoryless state feedback control laws is also given. Finally, a numerical example illustrates the effectiveness and the availability for the proposed method.

• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.9-15
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• 2019

In this paper, dynamic analysis of a nonlinear active vibration absorber is conducted with a time delay acceleration feedback to suppress the vibration of a nonlinear single degree of freedom primary system. The primary system consisting of linear and nonlinear cubic springs, mass, and damper is subjected to the multi-harmonic hard excitation with a parametric excitation. It is proposed to reduce the vibration of the primary system and the absorber by using a lead zirconate titanate (PZT) stack actuator in series with a spring in the absorber which configures as an active vibration absorber. The method of multiple scales (MMS) is used to obtain the approximate solution of the system under the internal resonance, subharmonic, superharmonic, and principal parametric resonance conditions simultaneously. Frequency and time responses of the system are investigated considering a delay in the feedback for the various parameters of the absorber configuration and controlling force.