보행 운동학을 위한 기계학습 기반 마커리스 측정 시스템: Part 2 - 비 병리적 보행 및 통계 데이터베이스

최형연,한만용,김성주,김하용,이한철,유태근 사단법인 한국융합기술연구학회 2024 아시아태평양융합연구교류논문지 Vol.10 No.1

본 연구는 시스템 소개 및 검증을 통해 검증한 마커리스 모션 캡처 기술(MMC 방법)을 사용하여 비병리적 보행 운동학(트레드밀 보행 및 지상 보행)에 대한 데이터베이스를 구축하고 통계적으로 분석을 진행하였다. 보행지표(케이던스, 어깨 및 골반 수평각, 어깨, 고관절, 무릎, 발목 관절의 굴곡/신전 동작)의 평균 및 표준편차를 평가하고, 마커리스 방법의 비병리학적 보행 표준 데이터로 활용하였다. 통계분석 결과, 비병리적 트레드밀 보행에서 보행 속도는 보행 운동학에 유의한 영향을 미치는 것으로 나타났다. 그리고 보행 유형(트레드밀 보행 및 지면보행)도 일부 보행 운동학에 영향을 미치는 것을 확인하였다. 사례연구로 병리학적 지면보행과 비병리적 보행을 비교하여 그 차이를 확인하였다. 비병리적 보행에 대한 이 데이터베이스는 의공학 및 의료 산업에 일반적으로 적용되는 중요한 목적 중 하나인 병리적 보행의 비교 평가에 유용할 것으로 보인다. This study established a database on non-pathological gait kinematics (treadmill gait and overground gait) and conducted statistical analysis, using markerless motion capture technology (MMC method) verified through system introduction and verification. Data were collected in three ways, and the collected gait images were analyzed using the MMC method gait analysis system. The mean and standard deviations of gait parameters, such as cadence, shoulder and pelvic horizontal angle, and flexion/extension motions at shoulder, hip, knee, and ankle joints, were evaluated to be utilized as non-pathologic gait norm data of the markerless method. As a result of statistical analysis, the gait speed in non-pathological treadmill walking was found to have a significant effect on some gait kinematics, such as shoulder horizontal angle, shoulder joint angle, hip joint angle, and knee angle. And the gait type (treadmill gait and over ground gait) also affected some of the gait kinematics. As a case study, pathologic over-ground gait was compared with non-pathological gait, and differences were found in the shoulder and pelvis horizontal angle patterns and the timing of maximum flexion/extension of the shoulder joint and lower extremity joint. This database of non-pathologic gait would be valuable for the comparative assessment of pathological gaits, which was one of the significant purposes of general application to the biomedical and healthcare industries.

INJURY RISK PREDICTION USING ELDERLY DIGITAL HUMAN BODY MODEL

최형연 한국자동차공학회 2015 International journal of automotive technology Vol.16 No.3

Frontal crash sled simulation is performed with Hybrid III dummy and elderly human body model to assess the relative high injury risk of older population. The sled model representing a typical driver side seat with a restraint system is validated against the test result. The current restraint design is tailored to the younger generation and found to be less effective for the older driver. The 48kph frontal crash simulation predicted AIS 4 level chest injury (7 rib fractures) of the elderly driver while 10 % risk of rib fracture was found with the Hybrid III dummy.

충돌해석을 이용한 도로 안전 시설물의 설계

최형연,이인혁,고순탁 한국전산구조공학회 2001 전산구조공학 Vol.14 No.1

Cementless 인공고관절 대퇴골부위의 2차원 유한요소해석

최형연,채수원,김성곤 대한기계학회 1994 대한기계학회 춘추학술대회 Vol.- No.-

OCCUPANT INJURY RISK ANALYSIS AT NASS/CDS DATABASE

최형연,신재호,오창진,배진호 한국자동차공학회 2017 International journal of automotive technology Vol.18 No.5

Injury information for vehicle occupants from the body regions of the head, thorax, abdomen, and upper and lower extremities, due to the restraints and interior parts of the vehicle, were extracted from the 2009 ~ 2012 NASS/CDS database. For those cases with high occurrence frequency, a detailed and comprehensive data analysis was performed to find the relationship between the accident, occupant, vehicle, and injury data. A numerical frontal impact sled model with the Hybrid III dummy and the GHBMC human body model was constructed to simulate and identify those injury risks according to NASS/CDS. Among the 5,734 injuries to the aforementioned body regions from frontal crashes are, listed by frequency of occurrence, the lower extremity (27.8 %), upper extremity (21.3 %), thorax (15.1 %), face (10.9 %), spine (8.7 %), head (7.3 %), and abdomen (6.9 %). The main injury sources to the head were the windshield, side structure, and steering wheel. For the thorax and abdomen they were the seat belt and steering wheel. For the lower extremity it was the instrument panel. The main injury patterns for the head were the concussion and the contusion. For the thorax they were vessel laceration and lung contusion. For the abdomen they were laceration and contusion of the organs. For the lower extremity they were bone fracture and ligament rupture. The steering wheel and seat positions were main factors affecting head and thorax injury risks. From the sled impact simulation, high injury risks of the head and thorax were assessed respectively at conditions of steering column tilt down and rear most seat position, which correlated well with the findings from the NASS/CDS data analysis.

보행 운동학을 위한 기계학습 기반 마커리스 측정 시스템: Part 1 - 시스템 소개 및 검증

최형연,한만용 사단법인 한국융합기술연구학회 2024 아시아태평양융합연구교류논문지 Vol.10 No.1

보행 분석(GA)은 사람이 걷는 방식을 기록, 분석 및 해석하는 과정으로, 보행에 영향을 미치는 상태를 갖는 사람 평가하고 치료하기 위해 임상적으로 사용한다. 가장 일반적인 GA 시스템은 OMC(Optical Marker Tracking System)이지만 여러 가지 단점을 가지고 있어 최근에는 자동 골격 추적 알고리즘을 갖춘 기계 학습 기반의 마커리스 모션 캡처 기술이 도입되었다. 보행 분석에서 MMC 방법의 실제 적용이 가능함을 보장하기 위해서는 추정된 관절 위치의 정확성을 검증해야 한다. 보행 시 MMC 자세 추정의 정확도를 정량화하기 위해 Mediapipe 자세 추정으로 구한 특징점 위치의 분산을 노이즈로 설정하고 무릎 관절 각도를 대표적인 신호로 선택하였다. 또한 이러한 마커리스 보행 분석 시스템 중 하나를 사용하여 정량적 검증을 수행하였다. 검증 프로세스는 세 가지 하지 관절 각도에 중점을 두고 두 가지 다른 모션 캡처 방법 (광학식 및 관성 센서식)과 비교하였다. 보행 시 무릎 관절 각도의 가장 좋은 상관관계는 평균 CORA 점수 0.92를 보였고 가장 낮은 상관관계는 평균 CORA 점수 0.47로 확인되었다. Gait analysis (GA) is the process of recording, analyzing, and interpreting the way a person walks, and is clinically used to assess and treat individuals with conditions affecting their ability to walk. The most typical GA system is the optical marker tracking system (OMC), but it has several drawbacks, and thus more recently, machine learning-based markerless motion capture technologies have been introduced with automatic skeleton tracking algorithms. For ensuring the practical application of the MMC method in the gait analysis, the accuracy of estimated joint positions needs to be verified. To quantify the accuracy of MMC pose estimation at a gait, scatters of keypoint positions from the Mediapipe pose estimation become the noise while the knee joint angle was chosen as a representative signal. Also, using one of these markerless gait analysis systems, a quantitative validation has been performed. The variance of the key points measured while walking was quantified as noise, and the knee joint angles were compared between the case where noise was assumed to occur at the maximum and the normal case. The validation process focused on three lower extremity joint angles and compared with two other motion capture methods, i.e., with optical maker and inertia sensor. The knee joint gait angle showed the best correlation (0.92 mean CORA score) while the worst correlation (0.47 mean CORA score) was obtained.

인공고관절 골흡수로 인한 응력분포 변화의 2차원 유한요소 해석

최형연,채수원,김성곤,Choi, Hyung-Yeon,Chae, Soo-Won,Kim, Sung-Kon 대한의용생체공학회 1995 의공학회지 Vol.16 No.1

Clinically, proximal bone resorption in the femur is frequently seen postoperatively on the follow up XI-rays after total hip replacement (THR). We developed the finite element model of cementless THR. The model is two dimensional side plate model, whereby the three dimensional structural integrity of the bone can be accounted for by a separate two dimensional mesh, a side plate. The subject of this article is the development and application of this two dimensional side plate FEM to study the reverse effect of the various degree of bone resorption of femur after THR. The results of this study indicates that 1) two dimensional side plate model is good and simple alternative to complex three dimensional model and 2) the severity of the proximal bone resorption has the effect of more increasing stress on the cortex at the level of femoral stem tip.

차량 시트용 저밀도 폴리우레탄 폼의 정적, 동적 특성의 실험적 규명

崔亨然,史聖鎭 弘益大學校 科學技術硏究所 2004 科學技術硏究論文集 Vol.15 No.-

Today's automotive customers are asking for vehicles that last longer, with higher expectations in durability, appearance, and comfort performance. Comfort performance has developed into a central theme of vehicle seating design due to the role of the seat as the interface between the vehicle and the human. Low density polyurethane foam continues today as the premier cushioning material utilized in automotive seat applications. Historically, polyurethane foam has been classified and determined by IFD(Indentation Force Delflection) curve and density. however dynamic properties, as dynamic stiffness and transmissibility, are more important than static properties because the in-serve mode of an automotive seat is dynamic condition rather than static. The objective of this study is to attain data on the responses of low density polyurethane foam under static and dynamic conditions and to derive parameter values such as spring constant and damping coefficient for simple numerical model.

경골 Pilon 골절의 치료

최형연,김익수,문진호,이은식 최신의학사 1994 最新醫學 Vol.37 No.7

복합재료를 사용한 전기자동차 루프의 압괴해석 ( Crush Analysis for the Composite Roof of Electric Vehicle )

최형연,신재호,허기준,지동철,김진 대한기계학회 1995 대한기계학회 춘추학술대회 Vol.- No.-