• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.33-37
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• 2004

To meet an increasing demand for high performance in gun dynamic plant, both a precise and a fast response positioning are strongly required for the gun servomechanism control. A mode switching control(MSC) system, which includes a fine stabilizing controller, fast positioning one and a switching function, is widely used to meet this requirement. Stabilization is performed through PID controller, while proximate time optimal servo(PTOS) is used for target designation. Because gun dynamic have large damping comparing to acceleration, PTOS algorithm with damping is newly derived. This paper adopts the initial value compensation method that improve the transient response after switching. Some simulation results are given to show the effectiveness of our scheme.

• Physical Therapy Korea
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• v.22 no.1
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• pp.49-57
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• 2015

The purpose of this study was to investigate the dynamic balance and activity of internal oblique muscle, multifidus muscle, gluteus maximus muscle, biceps femoris muscle during the Y balance test following the wearing of pelvic compression belt. Forty healthy adults were recruited for this test. The dynamic balance score was estimated as the following: (anterior+posteromdial+posterolateral)/($3{\times}leg$ length)${\times}100$. The electromyography signals were measured through %reference voluntary contraction, which was normalized by reference voluntary contraction of Y balance test without wearing the pelvic compression belt. The paired t-test was carried out to compare the dynamic balance score and the activity of the trunk and hip extensor with and without the wearing of pelvic compression belt. The dynamic balance score of the Y balance test when wearing pelvic compression belt was significantly than when measured without wearing the pelvic compression belt (p<.05). The muscle activity of the internal oblique and the multifidus was significantly decreased when wearing pelvic compression belt (p<.05). The muscle activity of the gluteus maximus was significantly increased when wearing pelvic compression belt (p<.05). However, there was no significant difference in hamstring muscle activity, with or without wearing the belt (p>.05). In conclusion, this study shows that the wearing of pelvic compression belt affects trunk muscle and hip extensor muscle activity related to the pelvic mobility and stability and increases dynamic balance and also contributes to the stabilization of the external pelvic stabilization.

• Journal of Korean Neurosurgical Society
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• v.58 no.1
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• pp.43-49
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• 2015

Objective : $Dynesys^{(R)}$ is one of the pedicle-based dynamic lumbar stabilization systems and good clinical outcome has been reported. However, the cylindrical spacer between the heads of the screws undergoes deformation during assembly of the system. The pre-strain probably change the angle of instrumented spine with time and oblique-shaped spacer may reduce the pre-strain. We analyzed patients with single-level stabilization with $Dynesys^{(R)}$ and simulated oblique-shaped spacer with finite element (FE) model analysis. Methods : Consecutive 14 patients, who underwent surgery for single-level lumbar spinal stenosis and were followed-up more than 24 months (M : F=6 : 8; age, $58.7{\pm}8.0$ years), were analyzed. Lumbar lordosis and segmental angle at the index level were compared between preoperation and postoperative month 24. The von Mises stresses on the obliquely-cut spacer ($5^{\circ}$, $10^{\circ}$, $15^{\circ}$, $20^{\circ}$, $25^{\circ}$, and $30^{\circ}$) were calculated under the compressive force of 400 N and 10 Nm of moment with validated FE model of the L4-5 spinal motion segment with segmental angle of $16^{\circ}$. Results : Lumbar lordosis was not changed, while segmental angle was changed significantly from $-8.1{\pm}7.2^{\circ}$ to $-5.9{\pm}6.7^{\circ}$ (p<0.01) at postoperative month 24. The maximum von Mises stresses were markedly decreased with increased angle of the spacer up to $20^{\circ}$. The stress on the spacer was uneven with cylindrical spacer but it became even with the $15^{\circ}$ oblique spacer. Conclusion : The decreased segmental lordosis may be partially related to the pre-strain of Dynesys. Further clinical and biomechanical studies are required for relevant use of the system.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.331-339
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• 2013

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 $30^{\circ}$ 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.

• Journal of Korean Neurosurgical Society
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• v.46 no.5
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• pp.431-436
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• 2009

Objective : This study examines whether functional motion is present at one or more years after Bioflex System placement. BioFlex System is a flexible rod system which has been used to preserve motion at the area of implantation. There has not been a scientific study showing how much motion is preserved after implantation. Methods : A total of 12 consecutive patients underwent posterior dynamic stabilization using the BioFlex System. Six patients were treated using a L3-4-5 construct and other six patients using a L4-5-S1 construct. Follow-up ranged from 12 to 33 months and standing neutral lateral, extension, flexion and posteroanterior (PA) radiographs were obtained at 3, 6, 9, and 12 months and at more than 12 months postoperatively. Range of motion (ROM), whole lumbar lordosis, and ROMs of motion segments from L2 to S1 were determined. Results : Patients with a L3-4-5 construct demonstrated a decrease in mean ROM for whole lumbar decreased from 40.08 to 30.77. Mean ROM for L3-4 (6.12 to 2.20) and L4-5 (6.55 to 1.67) also decreased after one year. Patients with a L4-5-S1 construct demonstrated L4-5 (8.75 to 2.70) and L5-S1 (9.97 to 3.25) decrease of mean ROM at one year postoperatively. Lumbar lordosis was preservep at both L3-4-5 and L4-5-S1 constructs. Clinical results showed significant improvements in both study groups. Conclusion : The present study provides preliminary information regarding the BioFlex motion preservation system. We conclude that the BioFlex System preserves functional motion to some degree at instrumented levels. However, although total lumbar lordosis was preserved, ROMs at implantation segments were lower than preoperative values.

• Journal of Korean Neurosurgical Society
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• v.58 no.5
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• pp.412-418
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• 2015

Objective : To investigate the effects of posterior implant rigidity on spinal kinematics at adjacent levels by utilizing a cadaveric spine model with simulated physiological loading. Methods : Five human lumbar spinal specimens (L3 to S1) were obtained and checked for abnormalities. The fresh specimens were stripped of muscle tissue, with care taken to preserve the spinal ligaments and facet joints. Pedicle screws were implanted in the L4 and L5 vertebrae of each specimen. Specimens were tested under 0 N and 400 N axial loading. Five different posterior rods of various elastic moduli (intact, rubber, low-density polyethylene, aluminum, and titanium) were tested. Segmental range of motion (ROM), center of rotation (COR) and intervertebral disc pressure were investigated. Results : As the rigidity of the posterior rods increased, both the segmental ROM and disc pressure at L4-5 decreased, while those values increased at adjacent levels. Implant stiffness saturation was evident, as the ROM and disc pressure were only marginally increased beyond an implant stiffness of aluminum. Since the disc pressures of adjacent levels were increased by the axial loading, it was shown that the rigidity of the implants influenced the load sharing between the implant and the spinal column. The segmental CORs at the adjacent disc levels translated anteriorly and inferiorly as rigidity of the device increased. Conclusion : These biomechanical findings indicate that the rigidity of the dynamic stabilization implant and physiological loading play significant roles on spinal kinematics at adjacent disc levels, and will aid in further device development.

• Physical Therapy Korea
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• v.18 no.1
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• pp.18-27
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• 2011

This study was to investigate the positive effects of specially designed trunk-stabilization exercise program on lower extremity balance of elderly with history of leprosy. In this participants, lower extremity functions has been undermined by the development of damage in peripheral nerves. A total of 40 elderly with history of leprosy were divided into 2 groups of equal size ($n_{1,\;2}=20$): a group that participated in the exercise program, and a control group that did not exercise but did continue to engage in normal daily activities (including walking). The exercise group exercised for 60 minutes 2 days a week for 12 weeks. Static balance ability was measured by asking study participants to a one leg standing test: dynamic balancing ability was measured with a tandem walking test and a timed up-and-go test. The participants in the exercise program and the control group were tested before and after completion of the exercise program for comparison, and then divided according to their ability to feel sensory in the soles of their feet into the categories of normal sensory group: group with sensory loss in one foot: and group with sensory loss in both feet. The participants in the exercise program showed a positive, statistically significant difference in static balance compared with the control group (p<.05) as measured using the one leg standing test. Similarly, the participants in dynamic balance (p<.05) as measured using the tandem walking and timed up-and-go tests. Finally, these improvements were related to the severity of sensory loss in the soles of the feet for all study participants.

• Journal of Convergence for Information Technology
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• v.7 no.4
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• pp.159-164
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• 2017

The aim of this study was to investigate the effects of scapular dynamic stabilization exercise(SDex) with electromyography(EMG) biofeedback on the upper trapezius(UT), pectoralis major(PM) and serratus anterior(SA) activities. Fifteen healthy male voluntarily participated in this study. A paired t-test was used for statistical analysis. The study showed, through EMG biofeedback, that EMG activity significantly decreased in the UT, PM and increased in the SA(P<0.05). These results suggest that SDex with EMG biofeedback is effective to selectively strengthen the SA. This article is meaningful in that it is the first article using SDex with EMG biofeedback.

• Physical Therapy Korea
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• v.26 no.4
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• pp.1-9
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• 2019

Background: Cervical dysfunction is a common pathomechanical marker in individuals with forward head posture (FHP). To overcome the limitations of the isometric chin-tuck (ICT) exercise, dynamic neuromuscular stabilization (DNS), which emphasizes an entire spinal chain exercise, has recently shown promising clinical results. Objects: Purpose of this study was to compare the immediate effects between ICT and DNS techniques. Methods: 43 young subjects (mean age, $24.0{\pm}5.0$ years) were recruited. Group of subjects with FHP were measured under baseline, ICT, and DNS conditions. Outcome measures included sitting height, longus colli (LC) and sternocleidomastoid (SCM) muscle thickness and LC/SCM thickness ratio. One-way repeated measures ANOVA was used to compare the continuous dependent variables among FHP, ICT, and DNS conditions at p<.016. Results: Both ICT and DNS exercise conditions yielded significantly increased LC muscle thickness, LC/SCM thickness ratio and sitting height than did FHP condition (p<.0001, respectively). Sitting height was significantly greater in DNS exercise than in the ICT exercise (p<.0001). Conclusion: The present results demonstrated that sitting height was greater in the DNS exercise than in the ICT exercise, as well as both corrective postural training exercises were effective on LC/SCM muscle balance ratio when compared with the baseline FHP condition. Therefore, it is considered that DNS exercise can be the recommended exercise for people with FHP.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.371-371
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• 2000

A strategy for the swing-up control according to states of the 2-link rotational pendulum is proposed. The proposed controller consists of two modes of control such as divergence mode and stabilization mode. When the controller is in divergence mode, control input is generated using sinusoidal and signum function to make the first and second links reach the bottom and top positions, respectively. After the controller finishes divergence mode, stabilization mode is initiated to keep the pendulum around the top position using pole-placement method. Dynamic models including actuator dynamics are obtained using coordinate changes at each control mode. Simulation results are given to show the effectiveness of the proposed method.