• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.36-42
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• 2003

• Korean Journal of Applied Biomechanics
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• v.19 no.3
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• pp.435-448
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• 2009

The purpose of this study was to investigate the kinemaitc gait parameter of lower extremities with different gait conditions(level walking, stairs, ramp) in old adults. Fourteen healthy older adults participated in this study and kinematic data were measured using 3D motion analysis system(Vicon, Oxford Metrics, England). Statistical analysis was used one-way ANOVA to know the difference of lower extremities angle at each gait phase with a different gait conditions. In sagittal plane, pelvic anterior tilt increased in stairs and ramp climbing and hip and knee flexion increased in stairs climbing but ankle dorsiflexion increased in ramp climbing. In frontal plane, pelvic was up in stairs and hip abduction and adduction more changed in stairs climbing than level walking. Knee varus and ankle inversion increased in stair climbing. In horizontal plane, pelvic internal rotation increased in stairs and ramp climbing and knee internal rotation increased in stairs climbing but ankle external rotation increased in stairs climbing. This results was shown that the stairs and ramp climbing changed the kinematic gait parameters of lower extremities in healthy old adults.

• Journal of Biomedical Engineering Research
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• v.24 no.4
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• pp.363-367
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• 2003

Contact area and pressure are important factors which directly influence a life of knee implants. Since implant's mechanical functions should be experimentally evaluated for clinical use, many studies using a knee simulator and a pressure sensor system have been conducted. However it has not been reported that the contact pressure's distribution of a knee implant motion was estimated in real-time during a gate cycle. Therefore. the objective of this study was to analyze the contact pressure distribution for the motion of a joint using the knee simulator and I-scan sensor system. For this purpose, we developed a force-controlled dynamic knee simulator to evaluate the mechanical performance of artificial knee joint. This simulator includes a function of a soft tissue and has a 4-degree-of-freedom to represent an axial compressive load and a flexion angle. As axial compressive force and a flexion angle of the femoral component can be controlled by PC program. The pressure is also measured from I-scan system and simulator to visualize the pressure distribution on the joint contact surfaces under loading condition during walking cycle. The compressive loading curve was the major cause for the contact pressure distribution and its center move in a cycle as to a flexion angie. In conclusion, this system can be used to evaluate to the geometric interaction of femoral and tibial design due to a measured mechanical function such as a contact pressure, contact area and a motion of a loading center.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.289-289
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• 2004

보행 시작(Gait Initiation)은 정적 기립상태에서 출발하여 일정한 보행주기가 반복되기 전까지의 과정을 말한다. 이러한 보행의 시작은 아주 짧은 시간에 무의식적으로 이루어지는 움직이지만, 신경계의 조절 근육의 작용 및 생체역학적인 힘의 복합적인 통합에 의해 이루어진다. 노인의 낙상은 보행시작의 과정에 있어서 주로 신체노화와 질병으로 인한 균형 조절능력의 감소를 가장 큰 요인으로 보고 있다. 하지만 지금까지는 주로 운동역학과 동적 근전도에 대한 연구가 주류를 이루었다.(중략)

• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.207-214
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• 2010

The aim of this study was to investigate upper and lower limb muscle activity using EMG(electromyogram) sensors while walking and identify normal gait pattern using FSR(force sensing resistor) sensor. Fifteen college students participated in this study and their EMG and FSR signal were measured during stopping and walking trials. EMG signals from upper(pectoralis major and trapezius) and lower limbs(rectus femoris, biceps femoris, vastus medialis, vastus lateralis, semimembranosus, semitendinosus, soleus, peroneus longus, gastrocnemius medialis, and gastrocnemius lateralis) were obtained using the surface electrodes. FSR measured pressures on 8 areas of the sole of the foot during walking. EMG results showed that all muscle activities except for vastus lateralis and semimembranosus during walking had higher amplitudes than stopping. Additionally, muscle activities associated with stance and swing phase during walking were identified. Results on FSR showed that stance and swing phases were detected by FSR signals during a gait cycle. Eight gait phases－initial contact, loading response, mid stance, terminal stance, pre swing, initial swing, mid swing, and terminal swing- were classified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.6
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• pp.1235-1241
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• 2012

In this paper, each driving motor for leg joints on a robot is controlled by estimating the direction of the legs measuring each joint angle and attitude angle of robot. We used quadruped working robot named TITAN-VIII in order to carry out this experimental study. 4 load cells are installed under the bottom of 4 legs to measure the pressed force on each leg while it's walking. The walking experiments of the robot were performed in 8 different conditions combined with duty factor, the length of a stride, the trajectory height of the foot and walking period of robot. The validity of attitude control for quadruped walking robot is evaluated by comparing the pressed force on a leg and the power consumption of joint driving motor. As a result, it was confirmed that the slip-condition of which the foot leave the ground late at the beginning of new period of the robot during walking process, which means the attitude control of the robot during walking process wasn't perfect only by measuring joint and attitude angle for estimating the direction of the foot.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.227-229
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• 2012

한국해양연구원에서 개발하고 있는 해저보행로봇 CR200은 6개의 다리를 이용하여 해저면에서 보행으로 이동하며 정밀 해저탐사 및 작업을 수행할 수 있는 로봇이다. 운용자는 선상제어실에서 유선으로 연결된 CR200을 원격으로 모니터링하거나 제어한다. 특히 안정적인 보행을 위해서는 100Hz의 주기로 CR200의 상태 정보가 선상제어실로 전송되고, 선상제어실에서는 전송된 정보를 기반으로 제어 명령을 산출하여 CR200으로 전송해야 한다. 이러한 주기적인 실시간 제어를 위해서는 일반적으로 실시간 운영체제를 사용하지만, 본 논문에서는 실시간 운영체제를 사용하지 않고 시스템 시간 기반의 백그라운드 프로세스로 동작하는 소프트웨어 타이머를 사용하여 실시간 제어를 하는 방법을 제안하고, 성능 평가 결과를 제시한다. 제안한 방법의 실시간 속성을 검증하기 위하여, 현재 설계에서 운영체제로 고려하고 있는 우분투 10.04와 윈도우즈 7을 CR200에 탑재되는 Advantech 사의 PCM-3362 보드에 설치하여 소프트웨어 타이머의 성능을 10ms부터 100ms까지 각각 실험하였다. 실험결과에 따르면, 두 운영체제에서 모두 누락이 없이 타이머 동작이 수행되었으며, 10ms 간격으로 타이머를 동작하였을 때에 우분투에서는 평균 오차가 $41{\mu}s$이었고 윈도우즈 7에서는 7.7ms였다. 윈도우즈 7에서의 오차는 100Hz 제어 주기에 사용하기에 적합하지 않지만, 우분투에서의 오차는 제어 주기 간격의 0.41%에 불과하기 때문에 해저보행로봇의 실시간 제어에 영향을 주지 않는 오차이다. 따라서 CR200의 임베디드 컴퓨터와 선상제어실의 원격제어 컴퓨터는 우분투 운영체제 상에서 소프트웨어 타이머를 이용하여 상호 연동되도록 구현할 예정이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.8
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• pp.1722-1729
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• 2005

In this paper, we used the quadruped walking robot Titan-VIII in order to carry out this simulation of sway compensation trajectory. The attitude angle ${\phi}_r$ and ${\phi}_p$ is obtained from 3-D motion sensor that is attached at the center of robot body and the attitude control carried out at every 10[ms] for stable gait of robot. Duty factor, that is fixed at 0.5. When we change period T into 1.5, 2.0, 3.0[sec] each and moving distance per period is changed into 0.2, 0.3(m), we sim띠ate several walking experiment of robot. and then we analyze the experiment results if there are any difference between the imaginary ZMP and actual ZMP of robot and the stable gait of robot is realized.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.317-320
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• 2021

본 연구는 주기적인 알츠하이머 병의 중증도 모니터링을 위해 스마트 인솔을 통한 보행 특징 추출과 머신러닝 기반 중증도 분류의 성능에 대해 살펴보았다. 최근 고령화가 가속화되는 추세에 있어 치매 환자가 급증하고 있으며, 중증도가 심해질수록 필요한 치료 비용 및 노력이 급증하기 때문에 조기 진단이 최선의 치료 전략으로 보여진다. 환자 친화적이고 저비용의 관성 측정 장치가 내장된 스마트 인솔만을 사용하여 다양한 보행 실험 패러다임에서 환자의 보행 특징을 추출하고, 이를 알츠하이머 병의 중증도 진단을 위한 머신러닝 기반 분류기를 훈련시켜 성능을 평가한 결과, 숫자세기와 같이 뇌에 부하를 주는 하위 작업이 포함된 복합 보행을 측정한 데이터셋을 사용하여 훈련된 분류 모델이 일반 걷기 데이터셋을 사용한 모델보다 성능이 높게 나타나는 것이 관찰되었다. 본 연구는 안전하고 환경적 제약이 적은 방법을 사용하여 시기 적절한 진단뿐만 아니라 주기적인 중증도 모니터링 시스템의 일환으로 활용될 수 있을 것이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.799-807
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• 2017

In this paper, a new method is proposed for estimating pedestrians' walking velocity based on lower-limb kinematics and wearable inertial measurement unit (IMU) sensors. While the soles and ground are not in contact during the walking cycle, the walking velocity can be estimated by integrating the acceleration output of the inertial sensor mounted on the pelvis. To minimize the effects of acceleration measurement errors caused by the tilt of the pelvis while walking, the estimated walking velocity based on lower-limb kinematics is imposed as the initial value in the acceleration signal integration process of the pelvis inertial sensor. In the experiment involving outdoor walking for six minutes, sensor drift due to error accumulation was not observed, and the RMS error in the walking velocity estimation was less than 0.08 m/s.