• Sleep Medicine and Psychophysiology
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• v.4 no.2
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• pp.147-155
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• 1997

To assess the reliability of chronobiological models of sleep/wake regulation, it is necerssary that the models predict the data which has been studied in sleep research, and they should be generalized across all ages. To date, many adult human data on such models have accumulated, yet it is evident that a comprehensive theory of the biorhythmic aspects of sleep/wake states has not established. Circadian rhythms such as the time going to bed, sleep onset, slow wave sleep pressure, periodicity of REM sleep, daytime performance, and early evening alertness are resumed everyday. Even in adult humans, sleep is inherently polyphasic. In both the disentrained and entrained states, naps when allowed tend to recur in a temporally lawful manner. The monophasic sleep pattern of most industrial societies therefore appears to be purely of social origin. The endogenous biorhythmic nature of circasemidian sleep tendency is supported by the ubiquity of the phenomenon across all ages. The NREM/REM sleep cycle within sleep with its inherent physiological, endocrine, and neurochemical fluctuations represents the best-documented ultradian sleep rhythms. Also, a daytime ultradian variation in sleepiness with a periodicity similar to nocturnal NREM/REM cycle(BRAC hypothesis) is suggested. This review article provides a brief synoptic review of the evidences for circadian, circasemidian, and ultradian sleep/wake rhythms, and then the authour will suggest the issues which expedite fuller modeling of sleep/wake system, to be further discussed.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.12
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• pp.1065-1072
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• 2015

This paper is about the development of an insole sensor system that can determine the model of an exoskeleton robot for lower limb that is a multi-degree of freedom system. First, the study analyzed the kinematic model of an exoskeleton robot for the lower limb that changes according to the gait phase detection of a human. Based on the ground reaction force (GRF), which is generated when walking, to proceed with insole sensor development, the sensing type, location, and the number of sensors were selected. The center of pressure (COP) of the human foot was understood first, prior to the development of algorithm. Using the COP, an algorithm was developed that is capable of detecting the gait phase with small number of sensors. An experiment at 3 km/h speed was conducted on the developed sensor system to evaluate the developed insole sensor system and the gait phase detection algorithm.

• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.183-190
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• 1999

The purpose of this study was to develop a portable and convenient closed-loop contrel type electrical stimulator for patients with foot drop. This system restores walking movement as well as prevents from atrophy or necrosis of lower limb muscles and increases blood circulation in hemiplegic patients caused by traffic accident, industrial disaster or stoke. This system detects the changes of the ankle joint angle during walking, and then controls the stimulus intensity automatically to maintain the programmed level of the ankle joint angle. Also, this automatic system controls the stimulus intensity which is affected by increased electrode impedance resulting from long time use. The system detects the joint angle by an optical sensor and includes modified PID control which adjusts the stimulus intensity if the joint angle deviates from the preset value. Stimulus parameters are 30~80 volt, 40 Hz, and 0.2 ms. The system was applied to five hemiplegic patients for 42 days. Duration of stimulation was 15 min/day for the first week and then the duration was gradually increased to 30, 60, 90 and 120 min/day. The muscle force was increased up to 29.7%, muscle fatigue was decreased compared with the level before stimulation and the pattern of locomotion was improved. These results suggest that the electrical stimulator with closed-loop control type is more convenient and effective in restoration of locomotion of patients with foot drop than open-loop system.

• PNF and Movement
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• v.4 no.1
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• pp.45-50
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• 2006

Purpose : This study shows the movements of the ankle and the foot in walking stages, and helps to diagnose and treat the problems of the ankle and the foot. The foot in human is a mean of the transportation, body support, and shock absorber. However, the slightest changes in the anatomical position can cause a significant increase of the stress and force in the ankle and the foot. The regular compressive force in the ankle of the normal person is generated by the contraction of the gastrocnemius and popliteus muscles, and transmitted to the achilles tendon. The plantar flexion about 10 degrees occurs immediately after the heel strike, getting ready for the weight acceptance. The shear force about 80 % of the body weight is generated immediately after the heel off of the mid stance phase. In those who have a problem in the ankle, the compression force at the ankle decreased to 1/3 of the body weight, and the shear force decreased, and the compressive force was reached at their maximum level earlier than the normal people. Conclusion : Analysis of the movements at the ankle and the foot in walking phase can make the effort to diagnose and treat the ankle and foot with the problems. However, the further study is necessary.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.205-215
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• 2009

The purpose of this study is to investigate alterations of pregnant gait by means of 3 different treads of stairs. 9 subjects(body masses; $59.41{\pm}7.49$, $64.03{\pm}6.65$, $67.26{\pm}7.58$, heights; $160.50{\pm}6.35$ ages; $31.22{\pm}2.99$; parity; $1.67{\pm}0.71$) participated in three experiments that were divided by physiological symptoms(the early(0-15 weeks), middle(16-27 weeks) and last(18-39 weeks), and walked at self-selected pace on 4 staircases 3 trials. As extending the pregnancy period, cadence was shorter but cycle time was longer more and more and the difference of maximum and minmum moments between right and left knee joint moment was smaller. With the treads of stair decent lengthening, speed and stride lengths were increased. As extending the treads of stair decent, joint moments of both feet were particular traits, hip joint was asymmetric but joint moments of knee and ankle were symmetric. These findings may account for relation between the treads of stair and moments and suggest that women may adapt their gait to maximize stability and to control gait motion for themselves in pregnant women.

• Journal of Korea Entertainment Industry Association
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• v.15 no.7
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• pp.181-192
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• 2021

This study was conducted to investigate the effects of a participatory rehabilitation program on sit-rise and rise-to-walk test performances, and perception and motor skills in adults with medically vulnerable individuals and, adults with developmental disabilities in particular. Seventeen adults with developmental disabilities participated in a participatory rehabilitation program using resistance bands and exercise balls, for 60 minutes once weekly over 13 weeks. Their performances were measured before and immediately after the intervention, and 12 weeks after. The findings were as follows. In the sit-rise test, the number of times rising from sitting posture increased after the intervention versus before, but the difference was not statistically significant. In the rise-to-walk test, the performance showed statistically significant difference over time, and the post-hoc test showed a significant effect after the intervention versus before. There was no significant difference in perception and motor skills. In sum, the participatory rehabilitation program positively influenced dynamic balancing related to functional activities but had no significant effect on perception and motor skills, which is related to motor control and motor learning. It is suggested that to increase the participation in community activities, reduce fall risk, and improve dynamic balancing abilities in adults with developmental disabilities, participatory rehabilitation programs should be utilized to promote the physical wellbeing.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.1
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• pp.134-139
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• 2006

A energy efficiency of quadruped walking robot has been studied mathematical modeling, dynamic analysis or simulation by consumption energy per period. In this paper, We used the quadruped walking robot Titan-VIII in order to carry out this experiment. The total moving length is about 2[m] , the stride length is 0.1, 0.2. 0.3, and walking period is changed by 1.0, 1.5, 2.0, 2.5 3.0[sec] Per each stride length. So consumption energy of 15 cases are measured. As a result of this experiment we obtained the best energy efficiency when stride length was 0.3[m], and Period was 1.5[sec].

• Journal of Korean Physical Therapy Science
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• v.15 no.2
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• pp.53-60
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• 2008

Background: The purpose of present study was to investigate the effect of quadriceps femoris taping in normal gait using 3D motion capture technique. Method: Twenty healthy volunteers, have no musculoskeletal problems, were recruited as subjects for this study. In experimental group, 10 males (mean age : 23.6${\pm}$.40) and 10 females (mean age : 21.3${\pm}$.36) were included. Methods of therapeutic taping that taping of patellar inferior and medial gliding and quadriceps. To obtain the dynamic data, we captured the motion of subject attached markers without taping during repeated gaits five times or more in 7 m Capture volume of gait analysis center. The result was obtained as a mean value in three times. After taping on quadriceps femoris, the same procedure was carried out. Statistical analyses were performed using statistical software packagess SPSS WIN 12.0(SPSS, Chicago, IL, USA). Differences were tested for statistical significance using paired t-test, independent t-test, chi-squared test for comparisons between the male and female. Results: The date of 20 subjects who carried out the whole experimental course were statistically analyzed. 1. gait velocity was showed that female group had more significantly increased than male group(p<.05). 2. step length was showed that female group had more significantly increased than male group(p<.05). 3. step width was showed that female group had more significantly increased than male group(p<.05). Conclusion: Elastic taping on quadriceps femoris promoted cadence, gait velocity, step length and step width in normal subject group.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.165-175
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• 2008

An ankle-foot orthosis(AFO) is a brace for persons with gait disabilities to support or replace the function of ankle joint. Ankle-foot orthoses(AFO's) are usually prescribed to alleviate the drop-foot by constraining the excessive plantar flexion. The shape and the strength of the AFO are often based on 'trial and error' due to a lack of knowledge of the stress distribution in the AFO. In this study, an improved stress-freezing method was proposed to measure the stress distribution characteristics in the AFO. As a result, a photoelastic material with low freezing temperature was developed to measure the stresses under a person's direct contact loading condition. The three-dimensional stress-1rozen photoelastic models of AFO's for five stages of stance phase such as heel contact, foot flat, mid stance, heel off, and toe off were produced. The results of photoelastic analysis revealed that the stresses developed in the AFO were varied considerably from tensile to compressive or vice versa, during walking. At the posterior part of ankle joint in the AFO, the maximum compressive stress of 1.81MPa was observed in the mid stance, and the maximum tensile stress of 0.74MPa was observed during heel contact. The overall stress levels in the AFO's were low in the toe off phase. The results suggested that the posterior part of ankle joint might be the most fragile part in the AFO.

• Journal of Korean Society of Transportation
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• v.20 no.4
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• pp.123-134
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• 2002

감응식 신호운영변수 설계에 관한 연구는 정주기식 신호운영변수 설계의 그것보다 그 수준이 현저히 미비하며 이는 감응식 신호운영 특성을 반영한 평가방법의 부재로 감응식 운영변수의 평가가 불가능하였기 때문이다. 본 논문은 최근에 소개된 평균 감응현시 녹색시간 추정 수리모형을 이용하여 Highway Capacity Manual (HCM) 지체도를 최소화하는 최대녹색시간의 설계방안을 제시한다. - '최소녹색시간'과 '단위연장시간'은 보행자 횡단시간 및 차량 차두시간 등 지역별 운전자/보행자의 특성과 관련이 있어 일반적인 최적화 설계 수리모형의 적용에 무리가 있어 제외한다. 제안된 설계방안은 감응식 운영논리를 토대로 감응현시 군의 평균녹색시간과 평균주기를 산정하며, HCM 지체도를 평가하고, 가능한 대안 중 지체를 최소화하는 최대녹색시간 운영변수 군을 '혼혈 유전자 알고리즘'으로 도출한다. 현장실험을 통해 도출이 불가능한 실제 최적치를 Corridor Simulation(CORSIM)모형을 이용하여 추정하였고 이를 제안된 설계방안으로 도출된 최대녹색시간 운영변수' 값들과 비교하였다. 비교결과 교차로 v/c 비율이 1.0 보다 낮을 시는 제안된 방법을 통해 설계된 최대녹색시간 운영변수 군이 최소 CORSIM 지체도를 산출하는 최대녹색시간 운영변수 군과 동일한 것으로, v/c비율이 1.0보다 높을 시는 다른 것으로 결과되었다. v/c비율이 1.0 보다 높은 경우는 정주기식 교차로 운영에 효율적이라 감응식 운영의 필요를 벗어나므로 제안된 최대녹색시간 설계방안은 감응식 신호운영 필요범위 내에서 효율적이다. 기존의 최대녹색시간 설계는 정수기식 최적녹색시간을 기준으로 최대녹색시간을 추정하며, 그러한 과정을 돕기 위하여 추정범위(설계자가 범위 내에서 임의로 선택함)를 제시하는 것이 기존의 연구임을 비교하면 본 연구에서 제안하고 있는 설계방법의 의미가 크다.