• Physical Therapy Korea
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• v.19 no.3
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• pp.61-71
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• 2012

In daily activities, people often perform two or more tasks simultaneously. This is referred to as dual-tasking or multi-tasking. The purpose of this study was to examine the effects of performing dual tasks while using a mobile phone on static and dynamic postural stability. Twenty-four subjects were asked to stand on a force plate and then instructed to perform a balance task only (BT), a balance task while listening to music (BTL), a balance task while talking on the mobile phone (BTT), and a balance task while sending text messages (BTS). We used the BioRescue$^{(R)}$ to measure postural sway and limit of stability for static and dynamic postural stability. Also the star excursion balance test (SEBT) was used to measure dynamic postural stability. A one-way ANOVA with repeated measures was used to compare the effects of the BT, BTL, BTT, and BTS. The Bonferroni's post hoc test was used to determine the differences among four tasks. Carrying out the BTS significantly decreased the limit of stability compared with carrying out the BT, BTL, and BTT (p<.05). In limit of stability, total surface area of BTT was more significantly decreased than that of BT and total surface area of BTS was more decreased than that of BT, BTL and BTT (p<.05). In the SEBT, the BTS displayed significantly smaller reach distance values compared with the BT or BTL (p<.05). These findings suggest that performing the balance task while sending text message on the mobile phone decreases dynamic postural stability, whereas performing the same task while listening to music using the mobile phone does not. Therefore, it requires more attention to maintain dynamic balance while sending text messages.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.3
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• pp.217-225
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• 2013

Typical quadrotor aircraft use four differential thrust vectors to control the motion. In this study, we design a quadrotor aircraft using collective and cyclic control to improve the shortcomings of existing quadrotor aircraft. The quadrotor aircraft with cyclic control can fly at various attitudes due to the excessive control degrees of freedom. Hence the quadrotor aircraft with cyclic control is suitable as high performance aircraft. In this study, modeling and stability analysis of the quadrotor aircraft have been performed using FLIGHTLAB. LQR control systems were designed using linear models at various flight conditions and verified through nonlinear simulations using MATLAB.

• The Journal of Korean Physical Therapy
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• v.24 no.5
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• pp.291-299
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• 2012

Purpose: This study examined the improved sensory, hand function, postural balance and activities of daily living (ADL) through somatosensory stimulation, such as the facilitation of functional reaching and tactile, proprioceptive stimulus of the upper limb (UL) and hand. Methods: Seventeen stroke patients having problems with motor and somatosensory deficits were selected in Bobath Memorial Hospital adult rehabilitation center. The patients were divided into two groups; the sensorimotor deficit group (SMDG) and motor deficit group (MDG). Somatosensory stimulation on the UL, physical therapy and occupational therapy were carried out three times a week over a six week these treatments were performed in both group period. To compare each group, the following assessment tools were used: such as tactile detection thresholds (TDT), two point discrimination on the affected side (TPDas), unaffected side (TPDus) stereognosis (ST) manual function test, hand function on the affected side (HFas) and unaffected side (HFus), Postural Assessment Scale for Stroke (PASS) and Korean version Modified Barthel Index (K-MBI). Results: In the SMDG, somatosensory stimulation on the UL was statistically important for TDT, TPDas, TPDus (except for the thener), ST, hand function on HFas, on HFus, PASS length of displacement with foam (LDFSEO), and K-MBI. In the MDG, somatosensory stimulation on the UL was important for TDT, TPDas, TPDus (except index finger) length of displacement with the eyes open, LDFSEO, HFas, HFus, PASS and K-MBI. In addition, there was a significant difference in the PASS between SMDG and MDG. Conclusion: Somatosensory stimulation on the UL affects the sensory, hand function, postural control and ADLs performance.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.45-61
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• 2005

Stance is defined as any state in which the total mass of the body is supported by the feet. In order to maintain stance, the sum of gravito-inertial forces acting on the body must be registered by equal and opposite forces at the region of contact between the organism and the support surface. Balance is controlled by applying forces to the surface of support so as to maintain the body's center of mass vertically above the feet. for a muIti-segment organism, there can be a variety of ways in which balance can be controlled, since movements of different body segments can have similar effects on the control of balance. In general, the organism tends to have a body configuration that is aligned with gravito-inertial force when there are no external forces acting on it. If any segments of the body are not aligned with gravito-inertial force vector, a torque on that segment would tend to move the body's center of mass. The maintenance of postural stability is accomplished in humans by a complex neural control system. This requires organizing integrating and acting upon visual, vestibular, and somatosensory input, providing orientation information to the postural control system. The information necessary to control and coordinate movement is provided by the visual sense of eye position with respect to the surrounding surface layout, the vestibular sense of head orientation in the gravito-inertial space, and the somatic sense of body segment position relative to one another and to the support surface. In this study, perception and action capability was examined from various points of view. The underlying assumption of the study was that the change of postural configuration could be effected by organism, environment and task goal.

• Journal of Korean Physical Therapy Science
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• v.12 no.4
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• pp.25-31
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• 2005

이 사례연구는 2002년 10월 15일 칼에 의한 좌상으로 경추 3-4번의 불완전 척수손상을 입은 25세의 남자 환자가 최초 병원에서 2002년 12월 한달 간의 치료를 마친 후, 2003년 1월 3일부터 4월 28일까지 태릉에 위치한 N 재활센터에서 주 5회 2시간의 자세조절 훈련, 심폐지구력 훈련, 웨이트 훈련, 스포츠(축구, 소프트 볼), 여가활동(등산)의 프로그램을 적용하여 척추손상 환자의 사회적응을 돕기위한 재활 프로그램의 다양화를 꾀하기 위한 기초 선행 작업으로 시작되었다. 신체능력을 평가하기 위한 측정도구는 관절가동범위(Range of Motion), 수동근력검사(Muscle Manual Test), 경직(Spasticity), 신체체력(Physical Fitness), 발란스(Balance: one leg stand), 상대적인 등속성 하지근력(Isokinetic Muscle Strength) 그리고 신체조성(Body Composition)로 하였다. 재활기간을 통해 처음 시작 일자에서 45일 간격으로 3차례의 측정을(1월 3일부터 4월 28일까지 실시하였다) 실시하였다. 최초 환자의 상태는 부분적으로 일상생활의 도움을 받아야 하는 상태로 동작을 시작하려 할 때 경직이 발생되어 옷을 입고 벗기, 신발 신고 벗기, 운전, 식사, 보행과 계단보행, 경사보행에서 보조자의 도움이 필요했으며, 작은 물건 잡기와 글씨쓰기, 타이핑 작업은 불가능 한 상태였다. 또한 스포츠 활동과 여가활동 역시 불가능 한 상태였다. 3달 15일간의 기간 동안 환자는 복학을 준비하기 위해 적극적으로 치료에 임했으며, 결과는 다음과 같았다. 신체조성은 재활 훈련을 통해 체중, 체지방율(%), 복부지방율(WHR)의 많은 감소를 가져왔다. 경직을 측정하는 Ashworth Scale은 정상에 가깝게 감소하였다. 관절가동범위는 고관절, 무릎, 발목에서 모두 증가하였다. 수동근력검사(0-9)는 많은 향상을 가져왔다. 신체체력능력 항목에서 근지구력의 윗몸일으키기와 팔굽히기, 악근력, 유연성으로 앉아 체간 숙이기, 민첩성으로 사이드 스텝, 순발력의 서전트는 모두 크게 향상되었다. 환자의 일상능력에서도 옷을 입고 벗기, 신발 신고 벗기, 운전, 식사, 보행과 계단보행, 경사보행에서 보조자의 도움이 필요없었으며, 타이핑 작업은 5손가락을 모두 사용하지는 않았지만, 1분에 80타로 큰 향상을 가져왔다. 또한 축구와 소프트볼, 등산을 달에 1회 정도 실시하여 약간의 도움만으로 가능하게 되었다.

• Physical Therapy Korea
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• v.15 no.2
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• pp.30-37
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• 2008

Anticipatory postural adjustments are pre-planned by the central nervous system (CNS) before the activation of agonist muscles in the limbs, and minimize postural sway. Most previous studies on this topic have focused on upper-limb movement, and little research has been conducted on lower-limb movement. The purpose of this study was to investigate the recruitment order of left and right trunk muscles during limb movement. Fifteen healthy subjects (10 male, 5 female) were enrolled. Electro-myographic signals were recorded on the muscles of: (1) deltoid, lumbar erector spinae, latissimus dorsi and internal oblique during shoulder flexion, (2) rectus femoris, rectus abdominis, external oblique and internal oblique during hip flexion. During right upper limb flexion, the onset of left erector spinae muscle and left internal oblique muscle activity preceded the onset of right deltoid by 8.09 ms and 19.83 ms, respectively. But these differences were not significant (p>.05). A similar sequence of activation occurred with lower limb flexion. The onset of left internal oblique muscle activity preceded the onset of right rectus femoris muscle by 28.29 ms (p<.05). The onset of right internal oblique muscle activity preceded the onset of left rectus femoris muscles by 23.24 ms (p<.05). The internal oblique muscle was the first activated during limb movement. Our study established the recruitment order of trunk muscles during limb movement, and explained the postural control strategy of the trunk muscles in healthy people. We expect that this study will be used to evaluate patients with an asymmetric recruitment order of muscle activation due to impaired CNS.

• Journal of Korean Medicine Rehabilitation
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• v.19 no.3
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• pp.69-80
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• 2009

Objectives : The purpose of this study was to evaluate the effects of core stability training on postural control and balance of hemiplegia patients who are difficult to control posture due to stroke. Methods : Subjects of the study were consisted of 25 adult hemiplegia patients(experimental 12, control 13) who were receiving rehabilitation therapy in hospital. Its group had a core stability training program by a physical therapists for 40 minutes, five times a week for nine-week period. Measurements of postural assessment scale for stroke(PASS), berg balance scale(BBS) and manual function test(MFT) were evaluated at initial presentation(pretest) and after completion of the each therapy program(posttest). Independent t-test and paired t-test was utilized to detect the mean difference between the groups. Results : Firstly, the result of PASS showed that postural control was significantly increased after the completion of core stability training(p<.01). Secondly, the result of BBS showed that balance control was significantly increased after the completion of core stability training(p<.01) and general physical therapy(p<.01). Lastly, the result of MFT showed that upper extremity's motor function was significantly increased after the completion of core stability training(p<.001). Conclusions : This study showed that core stability training is an effective treatment strategy on postural control, balance and upper extremity's motor function.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.7
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• pp.574-581
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• 2012

Because of the exposed blade, the UAV using the rotors entail the risks during operation. While a wrapped duct around the fan blades reduces risks, it is a higher thrust performance than the same power load rotor. In this paper, for applying advantages of a ducted fan, the tri-ducted fan air vehicle configuration is proposed. The vehicle has three ducted fans. Two of them are the same shape and size and the third one is the smaller. It is possible to control a rapid attitude stability using thrust vector control. The equations of motion of the tri-ducted fan were derived. Lyapunov control input was applied to the system and stable inputs were derived. A nonlinear simulation was fulfilled by using parameters of a prototype vehicle. It verified a stable attitude and analyzed results.

• The Journal of Korean Physical Therapy
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• v.24 no.2
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• pp.134-142
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• 2012

Purpose: This study examined the effect on postural control during the stimulation of haptic touch with fingertip on the stable surface at quiet standing posture, squat flexion stage, 60 degrees squat stage and squat extension stage. Methods: The postural sway was measured on the force platform, while 30 subjects were squatting, under three different haptic touch conditions (No Touch [NT], Light Touch [LT], Heavy Touch [HT]), above the touch pad in front of their body midline. Three different haptic touch conditions were divided into 1) NT condition; squatting as right index fingers held above the touch pad, 2) LT condition (<1N); squatting as the touch pad was in contact with right index fingers pulp with a pressure not exceeding 1N and 3) HT condition; squatting as subjects were allowed to use the touch pad for mechanical support by transmitting onto it with as much force, choosing with their index fingers. Results: There was significant decrease in LT, rather than that of NT (p<0.01), and in HT, rather than that of LT (p<0.01), as the results of the distance and velocity of center of pressure (COP) in mediolateral direction at quiet standing position. In anteroposterior direction, the distance and velocity of COP in LT and HT showed significant decrease, when compared to that of the data of NT (p<0.01). There was no significant difference between the 3 conditions (NT, LT, and HT), with respect to the distance and velocity of COP in mediolateral direction, during dynamic balance (squat flexion stage, squat extension stage) (p>0.05). In anteroposterior direction, the results of the distance and velocity of COP in HT showed significant decrease when compared to that of the data of NT (p<0.05). Conclusion: Light touch, during the task, decreased the postural sway at static balance. The results suggest that haptic touch should be applied, appropriately, because it varies the effects according to different conditions.

• Korean Journal of Applied Biomechanics
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• v.24 no.3
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• pp.295-300
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• 2014

The purpose of this study was to investigate the effects on jump performance and balance in soccer player with functional ankle instability of difference of neuromuscular training. In 33 male college soccer player with functional ankle instability subjects of this study randomization, combined training group (group I, n=11), balance training group (group II, n=11) and control group (group III, n=11) that included in the plyometric training and balance training was classified group. The intervention was conducted three times a week for 8 weeks. Before and after intervention, measured in surface area ellipse and countermovement jump and countermovement jump with arm swing. Showed a significant improvement in postural control and jump performance from the combined training group and balance training group compared to the control group. Showed a significant improvement in countermovement jump from the combined training group compared to the balance training group. Combined training and balance training showed the increased jump performance and postural control in soccer player with functional ankle instability.