• 한국전문물리치료학회지
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• 제22권3호
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• pp.41-49
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• 2015

This study aimed to evaluate the surface area and velocity of center of pressure (COP) during one leg standing by stimulating the sensory system in normal adults. Thirty subjects were enrolled in this study. Subjects were asked to stand on one leg during testing conditions. Testing conditions included 6 different sensory stimulations as follows: eyes opened, eyes closed, eyes opened with vibrator, eyes opened with head-mounted display (HMD), eyes opened with vibrator and HMD, and eyes closed with vibrator. During each testing condition, the surface area and velocity of center of pressure were measured. There were significant differences in the mean surface area and the mean velocity of COP between the "eyes opened" condition and the other five testing conditions (p<.05). However, in the comparison between the "eyes closed" and "eyes opened with HMD" conditions, there were no significant differences in the tested parameters. This study shows that closing eyes or keeping eyes opened while using HMD to experience virtual reality has the same effect on one leg standing balance. This finding should be considered in the evaluation or intervention of balance, especially one leg standing balance and balance while standing with a small base of support.

• International Journal of Control, Automation, and Systems
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• 제4권3호
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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.

• 대한인간공학회지
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• 제30권5호
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• pp.605-611
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• 2011

Objective: The aim of this study was to investigate the influence of seat heights for optimizing the ingress/egress performance in the elderly people. Background: Recently elderly users have been increasing in number and the ease of ingress/egress of the vehicle becomes an important issue. Method: Seven elderly subjects participated in this study(age: 71.7${\pm}$3.6yr, height: 167.7${\pm}$5.4cm, weight: 68.1${\pm}$11.5kg). Each subject performed the sitting and rising task from comfortable seated position on the chair under the following conditions: (1) with a lumbar support and (2) without a lumbar support. We measured EMG activities of seven muscles(tibialis anterior, soleus, gastrocnemius, vastus lateralis, rectus femoris, biceps femoris and erector supinae) and ranges of motion in lower limb during sitting and standing from three different heights (400mm, 500mm and 600mm from ground) of slide-up seat. Results: Muscle activities and angular movements of hip and knee joints during standing-up and sitting-down with a high seat height(600mm) were reduced mean 30.4% in extensor muscles, 57.11% in flexor muscle, 18.74% in erector muscle and 31.0% in joints compared with a low seat height(400mm). Conclusion: Muscle activities and joint movements in hip and knee were reduced when rising/sitting from a high seat height(600mm) compared with a low seat height(400mm). Application: This study can be used to design vehicle that are easy to get in and out of by older peoples with or without impairments.

• 재활복지공학회논문지
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• 제10권4호
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• pp.251-257
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• 2016

소아균형검사(Pediatric Balance Scale)는 경증이나 중증의 운동손상을 지닌 학령기 아동에게 사용할 수 있는 균형검사도구이다. 본 연구의 목적은 경직성 양하지 뇌성마비 아동을 대상으로 소아균형검사와 시공간적 보행변수간의 상관관계를 알아보고자 하였다. 소아균형검사는 앉은 자세에서 일어나기, 선 자세에서 앉기, 의자에서 의자로 이동하기, 잡지 않고 서 있기, 한 다리로 서 있기, 제자리에서 $360^{\circ}$ 회전하기, 뒤돌아보기 등 총 14개 항목으로 구성하고, 시공간적 보행변수는 보행속도 및 보폭, 보거리, 보격, 분속수, 양하지 지지 시간을 포함한다. 모든 대상자들은 독립적으로 보행이 가능한 경직성 양하지 뇌성마비 아동이며, 숙련된 소아물리치료사에 의해 소아균형검사와 시공간적 보행변수를 측정하였다. 소아균형검사와 시공간적 보행변수 간의 상관관계를 분석하기 위해 피어슨 상관분석을 사용하였고, 통계학적 유의수준은 0.05로 설정하였다. 소아균형검사의 총점(r=.49~.58)과 세부항목 중 선 자세에서 앉기(r=.48~.60)와 선 자세에서 왼쪽/오른쪽 어깨 뒤로 돌아보기(r=.47~.53), 선 자세에서 바닥에 물건 집어 들기(r=.52~.69)는 보행속도와 보폭, 보거리, 분속수의 각 변수 사이에 모두 유의한 양의 상관관계를 보였으며, 소아균형검사의 대부분 항목이 양하지 지지 시간 간의 매우 높은 음의 상관관계(r=-.48~-.92)를 보여주고 있다. 이는 소아균형검사와 시공간적 보행변수는 높은 상관관계를 가진 것을 관찰 할 수 있었으며, 소아균형검사를 통해 뇌성마비 아동의 보행수준을 예견하는데 유용하게 적용될 것이다.

• Geomechanics and Engineering
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• 제11권6호
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• pp.757-769
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• 2016

Rail support modulus is an important parameter for analysis and design of ballasted railway tracks. One of the challenges in track stiffness assessment is its dynamic nature under the moving trains which differs it from the case of standing trains. So the present study is allocated to establish a relation between the dynamic and static stiffness of ballasted tracks via field measurements. In this regard, two different sites of ballasted tracks with wooden and concrete sleepers were selected and the static and dynamic stiffness were measured based on Talbot - Wasiutynski method. In this matter, the selected tracks were loaded by two heavy and light car bodies for standing and moving conditions and consequently the deflection basins were evaluated in both sites. Knowing the deflection basins respect to light and heavy loading conditions, both of static and dynamic stiffness values were extracted. Finally two definite relations were obtained for ballasted tracks with wooded and concrete sleepers.

• 한국의류산업학회지
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• 제2권5호
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• pp.430-436
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• 2000

The purpose of the study was to obtain the basic data on the self-adjusting ability of the support panty stockings. Ten healthy women in the twenties were selected as subjects and clothing pressure of 9 support panty stockings made of single covered yarn (SCY) and double covered yarn (DCY) were measured under the standard environmental condition for the study. Data was analysed statistically according to body postures, sides, and parks. The results were as follows: Clothing pressure according to body posture was order of 'sitting-on-a-chair', 'stepping-up-a-stair', and 'standing'. High clothing pressure was obtained in the parts of calf ($9.4gf/cm^2$) in 'standing' and knee (9.7 and $16.5gf/cm^2$) in both 'stepping-up-a-stair' and 'sitting-on-a-chair', respectively. The order of clothing pressure with body sides was 'front', 'side', and 'back'. The highest clothing pressure was knee ($18.8gf/cm^2$) on the front, thigh ($8.8gf/cm^2$) on the side, and calf ($6.4gf/cm^2$) on the back. Clothing pressure of DCY at abdomen and knee was a little higher than those of SCY 3. In terms of material structure variation, clothing pressure of thigh, calf and ankle with SCY was a little higher than those with DCY, while clothing pressure of abdomen and knee with DCY was a little higher than those with SCY.

• 대한인간공학회지
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• 제33권4호
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• pp.281-287
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• 2014

Objective: The objective of the study is to develop a portable assistance device to help elderly users reduce strain on the knee and leg muscle while the elderly are standing up. Background: The pose of standing up from a chair is a basic movement, but the elderly often have difficulty standing up due to their weak muscles. We focus on designing a solution that helps the elderly reduce physical problems and support them standing up. Method: This study consists of three parts. Part I explores the way to reduce the refrain of leg muscle while standing up from a chair. In the process of structural development, we found that the moment is minimized when user pushes down the armrests due to a decrease in the force acting on the center of mass. In part II, a user test of 20 participants was carried out to rank the order of comfort of two stimuli: the chair with fixed armrests and the chair with the four-link mechanism that we created-in three different ways; (1) to stand up without touching armrests, (2) to stand up by pushing down on fixed armrests, and (3) to stand up by pushing down on armrests and being supported by the mechanism. To examine the statistically significant differences among the rank means, a Friedman test was conducted. In part III, we analyze the results of the user test and interview feedbacks, focusing on establishing a design strategy from UPO and visualizing it in 1:1 scale. Results: In part I, we decided to develop the four-link mechanism. The bottom is lifted up as the link rises. In part II, based on the rank data, we empirically found that UPO was assessed as the most comfortable during the stimuli. The thigh angle is smaller and the bottom of UPO is separated from a seat. In part III, after assessing the results and feedbacks, we created a visualization strategy for UPO: light, friendly, and novel. Conclusion: The portable and non-mechanical UPO comprises a four-link system that lifts the user's hips while standing. It can help users avoid knee and leg muscle strain. Its universal design considers the elderly's difficulties. Application: In a future study, combining light and durable material in UPO is expected to increase its usability. And this study is an opportunity to design various types of standing assistance devices.

• 조명전기설비학회논문지
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• 제27권8호
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• pp.21-29
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• 2013

The functional behaviors of human standing postural control were investigated when they were exposed to long-term horizontal vibration in the sagittal plane. For complexity of human postural control, a useful alternative method that has been based on a black-box approach was taken; that is, where the feedback mechanism was lumped into a single element. A motor-driven support platform was designed as a source of vibration. The AC Servo-controlled motors produced continuous anterior/posterior (AP) motion. The data were analyzed both in the time and frequency domain. The cross-correlation and coherency functions were estimated. Subjects behaved as a non-rigid pendulum with a mass and a spring throughout the whole period of the platform motion, as consistent with the plan chosen for this study.

• 한국전문물리치료학회지
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• 제6권3호
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• pp.11-21
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• 1999

Human balance is maintained through a complex process involving sensory detection of body motions, integration of sensorimotor information within the central nervous system, and execution of appropriate musculoskeletal responses. The basic task of balance is to position the body center of gravity (COG) over some portion of the support base. When the COG extends beyond the base of support, the person has exceeded the limits of stability (LOS). At this point, a step or stumble is required to prevent a fall. Automatic postural responses operate to keep the COG over the base of support. They are a set of functionally organized, long-loop responses that act to keep the body in a state of equilibrium. There are four commonly identified automatic postural responses, or strategies. These are ankle strategy, hip strategy, suspensory (knee) strategy, and stepping strategy. Thus, the purpose of this study was to evaluate the LOS using various knee strategies. Forty subjects participated in this study. The subjects were comprised of 20 males and 20 females who were without neurologic, orthopaedic or balance performance impairments. The LOS was measured with a Balance Performance Monitor (BPM) Dataprint Software Version 5.3. The results of this study were as follows: 1) Knee joint angle which is to increase stability of standing balance with using knee strategy was at mid-range. 2) There were statistically significant differences in anteroposterior LOSs according to the knee strategy. 3) There were no statistically significant differences in mediolateral LOSs according to the knee strategy. 4) There were statistically significant differences of anteroposterior LOSs with using knee strategy according to gender. 5) There were no statistically significant differences in mediolateral LOSs with using knee strategy according to gender.

• 한국전문물리치료학회지
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• 제27권1호
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• pp.78-86
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• 2020

Background: Flat-footed persons with collapsed medial longitudinal arch lose flexibility after skeletal maturity, resulting in several deformities and soft tissue injuries. Although arch support taping is usually applied in the clinic to support the collapsed arch, research on the use of different types of tape for more efficient arch support in flat-footed persons is lacking. Objects: The purpose of this study was to examine three conditions (barefoot, kinesio tape, and dynamic tape) and compare their effects on static and dynamic balance in persons with asymptomatic flexible flatfoot. Methods: Twenty-two subjects (9 females and 13 males) with asymptomatic flexible flatfoot participated in this study. The subjects performed the Y-balance test to measure the composite reach score. The subjects also performed a 30-second standing test to measure the center of pressure (COP) path length and a walking test to measure anteroposterior and lateral variability using the Zebris FDM system. One-way repeated-measures analysis of variance compared the three conditions applied to the subjects' feet for each balance variable. Results: The composite reach score significantly increased following the application of dynamic tape compared with barefoot and that of kinesio tape compared with barefoot. There was no significant difference in the COP path length during standing among the three conditions. Anteroposterior and lateral variability during walking significantly with dynamic tape application compared with barefoot. Conclusion: The results of this study suggest that, in persons with asymptomatic flexible flatfoot, application of kinesio tape and dynamic tape may be effective in increasing the composite reach score in Y-balance test, whereas application of dynamic tape may be effective in reducing anteroposterior and lateral variability during walking.