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보행 관련 뇌파의 신호원 추정을 위한 비통합 데이터 분석 방법
송민수(Minsu Song),정지욱(Jiuk Jung),지인혁(In-Hyeog Jee),추준욱(Jun-Uk Chu) 한국전기전자학회 2021 전기전자학회논문지 Vol.25 No.4
보행능력은 의학적으로 다양한 뇌신경계 질환에서 사용되는 평가 지표이다. 보행에 관련된 뇌 활성화를 측정하고 분석하는 방법으로 뇌파 데이터에 대해 독립성분을 추출한 뒤 신호원 추정 및 시간-주파수 분석이 주로 사용된다. 기존의 트레드밀 기반보행 뇌파 분석은 분할 측정한 뒤, 데이터를 병합하여 신호 전처리, 독립성분분석 및 신호원 추정을 수행하고 피험자 간 군집화를 통하여 대표 성분 클러스터들을 추출한다. 본 연구에서는 보행 뇌파에 대하여 데이터 통합 없이 각각의 분할 측정된 데이터에 대하여 개별적으로 신호 전처리, 독립성분분석 및 신호원 추정을 수행하고 모든 피험자로부터 추정된 독립성분에 대하여 피험자 간 군집화를 수행하는 새로운 방법을 제안한다. 데이터 통합이 독립성분 군집화 및 시간-주파수 분석에 미치는 영향을 조사하기 위해 기존의 통합 데이터에 기반한 두 가지 분석 방법과 본 연구에서 제안하는 데이터 통합이 없는 분석 방법을 비교하였다. 그 결과, 통합 데이터 방법들에서는 각각 2개씩의 성분 클러스터를 도출하였으나 제안하는 방법을 통해 4개의 성분 클러스터를 도출, 적은 피험자 수에도 불구하고 세분화된 보행 뇌 신호 성분 클러스터를 도출할 수 있었음을 확인하였다. Gait is an evaluation index used in various clinical area including brain nervous system diseases. Signal source localizing and time-frequency analysis are mainly used after extracting independent components for Electroencephalogram data as a method of measuring and analyzing brain activation related to gait. Existing treadmill-based walking EEG analysis performs signal preprocessing, independent component analysis(ICA), and source localizing by merging data after the multiple EEG measurements, and extracts representative component clusters through inter-subject clustering. In this study we propose an analysis method, without merging to single dataset, that performs signal preprocessing, ICA, and source localization on each measurements, and inter-subject clustering is conducted for ICs extracted from all subjects. The effect of data merging on the IC clustering and time-frequency analysis was investigated for the proposed method and two conventional methods. As a result, it was confirmed that a more subdivided gait-related brain signal component was derived from the proposed “non-merging” method (4 clusters) despite the small number of subjects, than conventional method (2 clusters).
발목형 로봇의족의 발걸림 위험 제어를 위한 갑작스런 충돌 상황에서의 보행패턴 분석
김정민(Jeongmin Kim),곽문규(Moonkyu Kwak),황동환(Dongwhan Hwang),정지욱(Jiuk Jung),우현수(Hyunsoo Woo),이용구(Yongkoo Lee) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
This study was performed to analyze human gait strategy of tripping over in order to control the robotic ankle prosthetics under amputees tripping over. The subjects were 7 men, who had no serious foot musculoskeletal disease within 1 years prior to study. When tripping over, we found out there were three types of patterns of tripping over, which were classified into type A, type B and type C according to the distance from the obstacle to supporting foot. The distinction between type A and type C was also related to the position of center of mass. A situation of higher risk occurred when center of mass was forward to the supporting foot. At the moment the ankle of tripped foot rapidly acted dorsiflexion. Authors recommend that when an accidental collision with an obstacle occurs during walking, tripped robotic foots ankle should act dorsiflexion immediately.
발걸림 상황에서의 보행패턴 : 무게중심의 위치에 따른 무의식적인 회복전략 선택
김정민(Jeongmin Kim),곽문규(Moonkyu Kwak),황동환(Dongwhan Hwang),정지욱(Jiuk Jung),우현수(Hyunsoo Woo),이용구(Yongkoo Lee) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The objective of this study was to find out what made differences in unconscious selection of recovery strategy when tripping over. Seven subjects, who did not have any lower extremity musculoskeletal disorder within one year prior to the study, participated in this study. Eight infrared cameras and one force plate were used to analyze the gait patterns. A remotely controlled pop-up obstacle to randomly trip over subjects was installed within pathway in front of the force plate. As a result, three types of recovery strategy were observed immediately after tripping over. An elevating strategy of lifting the tripped foot, was grouped into type-A₁ and type-A₂ with respect to swing phase time, maximum height of lower extremity, joint angle and moment, and joint angular velocity; meanwhile, a lowering strategy in which the tripped-foot was unable to surmount the obstacle was grouped as type-B. These three types were categorized in accordance with the COM position. The relative position between the supporting-foot and the COM was found to significantly impact the unconscious selection of recovery strategy when tripping over.
운전자 졸음 및 각성 상태 시 ECG신호 처리를 통한 심장박동 신호 특성 연구
이은지(EunJi Lee),이미래(Mirae Lee),김민수(Minsoo Kim),김윤년(Yoonnyun Kim),정지욱(Jiuk Jung),오성호(Sungho Oh),이재열(JeaYeol Lee),허윤석(Yunseok Heo) 한국자동차공학회 2013 한국자동차공학회 학술대회 및 전시회 Vol.2013 No.11
Traffic accident increase from carelessness driving is a serious problem in society with falling asleep at the wheel being responsible of about 23% of all traffic accidents. Distinct features in heart rate signals during the driver’s wake and sleep states could provide an initiative for the development of a safe driving systems such as drowsiness detecting sensor in a smart wheel. We measured ECG from 5 adult subjects during the wake and sleep states. After detecting R-peaks in ECG signal, heart rate signal was obtained. Heart rate variability was investigated for three different frequency regions; very-low-frequency (VLF), low-frequency (LF), and high-frequency (HF). The average power in VLF and LF frequency band increased from 14% to 21.6% and 38.87% to 40.53% respectively, while for HF band it reduced from 47.2% to 37.83%. The LF/HF ratio for sleep state (1.126) was larger than for wake state (0.082). In conclusion, there are changes in heart rate from wake to sleep that are potentially to be detected. The results in our study could be useful for the development of drowsiness detection sensors for effective real-time monitoring.
발걸림 상황에서의 보행패턴 : 무게중심의 위치에 따른 무의식적인 회복전략 선택
김정민(Jeongmin Kim),곽문규(Moonkyu Kwak),황동환(Dongwhan Hwang),정지욱(Jiuk Jung),우현수(Hyunsoo Woo),이용구(Yongkoo Lee) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The objective of this study was to find out what made differences in unconscious selection of recovery strategy when tripping over. Seven subjects, who did not have any lower extremity musculoskeletal disorder within one year prior to the study, participated in this study. Eight infrared cameras and one force plate were used to analyze the gait patterns. A remotely controlled pop-up obstacle to randomly trip over subjects was installed within pathway in front of the force plate. As a result, three types of recovery strategy were observed immediately after tripping over. An elevating strategy of lifting the tripped foot, was grouped into type-A₁ and type-A₂ with respect to swing phase time, maximum height of lower extremity, joint angle and moment, and joint angular velocity; meanwhile, a lowering strategy in which the tripped-foot was unable to surmount the obstacle was grouped as type-B. These three types were categorized in accordance with the COM position. The relative position between the supporting-foot and the COM was found to significantly impact the unconscious selection of recovery strategy when tripping over.