• 대한인간공학회지
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• 제35권5호
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• pp.319-341
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• 2016

Objective:This research analyzed the lower-limb motion in kinetic and kinematic way while walking on various terrains to develop Foot-Ground Contact Detection (FGCD) algorithm using the Inertial Measurement Unit (IMU). Background: To estimate the location of human in GPS-denied environments, it is well known that the lower-limb kinematics based on IMU sensors, and pressure insoles are very useful. IMU is mainly used to solve the lower-limb kinematics, and pressure insole are mainly used to detect the foot-ground contacts in stance phase. However, the use of multiple sensors are not desirable in most cases. Therefore, only IMU based FGCD can be an efficient method. Method: Orientation and acceleration of lower-limb of 10 participants were measured using IMU while walking on flat ground, ascending and descending slope and stairs. And the inertial information showing significant changes at the Heel strike (HS), Full contact (FC), Heel off (HO) and Toe off (TO) was analyzed. Results: The results confirm that pitch angle, rate of pitch angle of foot and shank, and acceleration in x, z directions of the foot are useful in detecting the four different contacts in five different walking terrain. Conclusion: IMU based FGCD Algorithm considering all walking terrain possible in daily life was successfully developed based on all IMU output signals showing significant changes at the four steps of stance phase. Application: The information of the contact between foot and ground can be used for solving lower-limb kinematics to estimating an individual's location and walking speed.

• 한국운동역학회지
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• 제26권1호
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• pp.135-142
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• 2016

Objective: The purpose of this study was to investigate the acute effect of walking on high heels on the behavior of fascicle length and activation of the lower limb muscles. Methods: Twelve healthy inexperienced high heel wearers (age: $23.1{\pm}2.0yr$, height: $162.4{\pm}4.9cm$, weight: $54.4{\pm}8.5kg$) participated in this study. They walked in high heels (7 cm) and barefoot on a treadmill at their preferred speed. During the gait analysis, the lower limb joint kinematics were obtained using a motion analysis system. In addition, the changes in fascicle length and the level of activation of the medial gastrocnemius (MG) were simultaneously monitored using a real-time ultrasound imaging technique and surface electromyography, respectively. Results: The results of this study show that the MG fascicle operates at a significantly shorter length in high heel walking ($37.64{\pm}8.59mm$ to $43.99{\pm}8.66mm$) in comparison with barefoot walking ($48.26{\pm}9.02mm$ to $53.99{\pm}8.54mm$) (p < .05). In addition, the MG fascicle underwent lengthening during high heel walking with relatively low muscle activation while it remained isometric during barefoot walking with relatively high muscle activation. Conclusion: Wearing high heels alters the operating range of the MG fascicle length and the pattern of muscle activation, suggesting that prolonged wearing of high heels might induce structural alterations of the MG that, in turn, hinder normal functioning of the MG muscle during walking.

• 한국운동역학회지
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• 제29권2호
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• pp.79-88
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• 2019

Objective: The aim of this study was to determine the peak torques of the knee and ankle joint and local stability of the lower extremity's joints, and muscle activation patterns of the lower extremity's muscles between fallers and non-fallers in the elderly women during walking. Method: Four elderly women (age: $74.5{\pm}5.2yrs.$; height: $152.1{\pm}5.6cm$; mass: $55.3{\pm}5.4kg$; preference walking speed: $1.19{\pm}0.06m/s$) who experienced falls within six months since experiment had been conducted (falls group) and thirty-six subjects ($74.2{\pm}3.09yrs.$; height: $153.6{\pm}4.9cm$; mass: $56.7{\pm}6.4kg$; preference walking speed: $1.24{\pm}0.10m/s$) who had no experience in falls (non-falls group) within this periods participated in this study. They were measured torque peaks of the knee and ankle joint using a Human Norm and while they were walking on a treadmill at their natural pace, kinematic variables and EMG signals were collected with using a 3-D motion capture system and a wireless EMG system, respectively. Lyapunov Exponent (LyE) was determined to observe the dynamic local stability of the lower extremity's joints, and muscles activation and their co-contraction index were also analysed from EMG signals. Hypotheses between falls and non-falls group were tested using paired t-test and Mann-Whitey. Level of significance was set at p<.05. Results: Local dynamic stability in the adduction-abduction movement of the knee joint was significantly lower in falling group than non-falling group (p<.05). Conclusion: In conclusion, muscles which act on the abduction-adduction movement of the knee joint need to be strengthened to prevent from potential falls during walking. However, a small number of samples for fallers make it difficult to generalize the results of this study.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.65-72
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• 2004

Long span structures with low natural frequencies such as shopping malls, large offices, and assembly rooms may experience signification dynamic responses due to human activities. In this study, equations to estimate the magnitudes of group walking loads are derived and a simple procedure to estimate and evaluate the corresponding response of the existing and new building structures subjected to human loads is proposed. The effectiveness of the proposed method is verified analytically using a simple floor and experimentally on a footbridge measuring the structural response induced by group pedestrians. Results indicatethat the amplitudes of group walking loads can be easily estimated if the mode shapes are available, and that the corresponding structural responses can be estimated easily by the simple response measurement using the proposed method.

• Structural Engineering and Mechanics
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• 제75권3호
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• pp.377-387
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• 2020

Modern long-span floor system typically possesses low damping and low natural frequency, presenting a potential vibration sensitivity problem induced by human activities. Field test and numerical analysis methods are available to study this kind of problems, but would be inconvenient for design engineers. This paper proposes a simplified method to determine the acceleration amplitudes of long-span floor system subjected to walking or running load, which can be carried out manually. To theoretically analyze the acceleration response, the floor system is simplified as an anisotropic rectangular plate and the mode decomposition method is used. To facilitate the calculation of acceleration amplitude a_P, a coefficient α_wmn or α_Rmn is introduced, with the former depending on the geometry and support condition of floor system and the latter on the contact duration t_R and natural frequency. The proposed simplified method is easy for practical use and gives safe structural designs.

• 한국군사과학기술학회지
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• 제18권3호
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• pp.309-315
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• 2015

This paper presents a lower-limb exoskeleton testbed and its control method. An exoskeleton is a wearable robotic system that can enhance wearer's muscle power or assist human's movements. Among a variety of its applications, especially for military purpose, a wearable robot can be very useful for carrying heavy loads during locomotion by augmenting soldiers' mobility and endurance. The locomotion test on a treadmill was performed up to maximum 4km/h walking speed wearing the lower-limb exoskeleton testbed with a 45kg backpack load.

• 대한기계학회논문집A
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• 제31권11호
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• pp.1115-1123
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• 2007

The foot plays an important role in supporting the body and keeping body balance. An abnormal walking habit breaks the balance of the human body as well as the function of the foot. The foot orthotics which is designed to consider biomechanics effectively distributes the load of the human body on the sole of the foot. In this paper, gait analysis was performed for three male subjects wearing the orthotics. In this study, three male subjects were selected. The experimental apparatus consists of a plantar pressure analysis system and digital EMG system. The gait characteristics are simulated by ADAMS/LifeMOD. The COP (Center of Pressure), EMG and ground reaction force were investigated. As a result of gait analysis, the path of COP was improved and muscle activities were decreased with orthotics on the abnormal walking subjects.

• 대한토목학회논문집
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• 제30권1D호
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• pp.17-25
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• 2010

우리나라는 지난 반세기 동안 급격한 경제적 성장을 기반으로 자동차의 급격한 증가로 인해 가장 오랜 세월동안 인간에게 있어서 이동을 위한 중요 교통수단이었던 보행(步行)이 자동차 통행에 밀려 그 중요성이 부각되지 못하고 있다. 이로 인해 보행은 하나의 교통수단으로 생각하지도 않고, 인간이 기본적으로 가져야 할 보행이 권리로써의 인식조차도 희박해져가고 있다. 따라서 본 연구는 자동차의 증가로 인해 보행권이 약화되는 현상에 대한 문제점을 제기하고, 교통안전부분에서 앞서가는 해외 일부 국가의 보행권 강화 정책을 살펴본 후, 현재 우리나라 보행자들의 보행환경에 대한 만족도와 보행권 강화를 위한 주민들의 의견을 반영한 해외의 보행안전 대책의 도입을 위한 제도적 장치를 제시하고자 한다. 본 연구의 성과를 정리하면, 첫째, 안심하고 보행할 수 있도록 보행자들의 보행의 자유를 보장하고, 둘째, 안전하고 편리한 보행이 이루어 질 수 있는 보행환경의 정비방법의 모색과 해외의 보행권 강화대책 중 우리나라의 실정에 잘 맞고, 보행자 보행안전을 향상시킬 수 있으며, 현재 보행자들이 우선적으로 희망하는 실용적인 대책이 무엇인지를 GAP 분석과 구조방정식을 통해 분석하였다. 셋째, 선별된 대책의 시행이라는 가정 하에 보행자들의 만족도를 분석하여 추후 정책선정에 기초적인 자료를 제공할 수 있었다.

• 한국콘텐츠학회논문지
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• 제18권1호
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• pp.173-184
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• 2018

보행 과정에서 여러 근육이 동시에 수축하는 운동 모듈 또는 근육 시너지는 매우 중요한 중추신경계 운동조절 메커니즘이다. 본 연구는 걷는 동안 근육 간 양성 및 음성 공변 패턴을 이해하는 것을 목표로 한다. 본 연구에서는 트레드밀 보행 시 발생하는 다리 근육 활성을 근전도 검사를 통해 측정하였다. 동시 수축근육 그룹, 즉 운동 모듈을 확인하기 위해 우리는 양쪽 4 개의 다리 근육(전경골근, 내측 비복근, 대퇴직근, 내측 슬괵근)에서 근전도 데이터를 수집하였고, 이를 바탕으로 비음수행렬분해 및 주성분 분석을 수행하였다. 이후 근육 또는 운동 모듈 간의 다양한 조합으로부터 공변이 값을 계산하였고, 이원배치분산분석을 이용하여 각 조합들에서 발생하는 공변이 패턴을 비교하였다. 그 결과, 다양한 조합 사이에 유의미한 공변이 값의 차이가 발견되었다(p < 0.05). 같은 운동 모듈로 정의된 특정 근육 사이에서 발생하는 근 활성은 양성공변이를 보여주었으나 운동 모듈 사이에서는 음성 공변이를 보여주었다. 모든 근육 조합들 사이에서는 음성 공변이가 발생하였다. 운동 모듈 사이에서 안정적으로 발생하는 음성 공변이는 운동 모듈이 복잡한 운동 조정의 제어 단위(control unit) 일 수 있음을 암시하고 있다.

• 한국정보통신학회논문지
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• 제8권7호
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• pp.1418-1423
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• 2004

관절형 로봇은 바퀴구동로봇에 비해 인간과 비슷한 형태를 갖추고 있어 친화성이 높고 관절로 인하여 자유도가 높으며 접지점을 임의로 설정할 수 있다. 또한 접지위치와 본체와의 상대위치를 자유로이 설정할 수 있으며 관절을 매니플레이터로서 사용할 수도 있는 장점을 가지고 있다. 이에 반해 많은 자유도를 가지고 있어 기구가 복잡하고 이동속도가 바퀴구동로봇에 비해 늦으며 이동시 진동이 일어나기 쉽고 로봇이 넘어지지 않도록 하는 특별한 제어가 필요하게 된다. 많은 생물들의 기본다리인 4족형 구조는 동적안정을 유지하면서 이동을 계속할 수 있고, 또 보행중에도 기구적으로 쓰러짐을 회피할 수 있는 완전보행을 실현하는 최소한의 관절수로 구성되어 있는 보행형태이다. 이러한 보행실험을 위해 4족 보행로봇인 TITAN-VIII을 이용하여 Trot 보행 알고리즘을 연구하여 보행 실험을 행하였다.