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중량물 들고 내리기 농작업 자세의 에너지 소모량 평가 시스템 개발
심태용 ( Taeyong Sim ),김보리 ( Bori Kim ),윤수현 ( Su Hyun Youn ),문정환 ( Joung Hwan Mun ) 한국농업기계학회 2017 한국농업기계학회 학술발표논문집 Vol.22 No.1
농작업 자세 중에서 중량물을 반복적으로 들고 내리는 자세는 요통과 같은 근골격계 질환의 유발행위로 분류된다. 이는 인간공학적 유해요인 평가도구에 의해 위험도 별로 정량화 할 수 있다. 이러한 평가방법은 농작업 자세를 개선하여 근골격계 질환을 예방할 수 있다는 측면에서 매우 중요하다. 그러나 기존의 작업자세 부하 평가방법들은 동적 자세를 평가하는데 있어 어려움이 있을 뿐 만 아니라 평가 과정에서 관찰자의 주관성이 개입 될 수 있다는 한계점을 갖고 있다. 이에 본 연구에서는 중량물을 들고 내리는 동적 자세에서 발생하는 부하를 Energy expenditure를 이용하여 평가할 수 있는 시스템을 개발하는 것이다. Energy expenditure는 체중, 성별 등과 같은 작업자 관련 변수와 중량물의 무게, 들어 올리는 높이, 빈도수등과 같은 작업환경 관련 변수를 이용하여 최대 산소소비량을 예측하는 방법이다. 본 연구에서 제안하는 작업자 및 작업환경 관련 변수를 자동 측정하는 시스템은 초음파 거리측정 센서와 깔창 형태의 센서를 이용하여 구성하였다. 이를 통해 남성(6명), 여성(6명)을 대상으로 20kg의 중량물을 들고 내리는 동작에서 발생하는 Energy expenditure 값을 산출하였고, 산소소비량 측정 장비를 통해 획득된 최대 산소소비량(VO2)과 비교하여 검증하였다. 여성을 대상으로 한 Energy expenditure 값과 최대 산소소비량 간 상관관계는 0.984로 나타났으며, 남성의 경우에는 0.998로 높은 상관관계를 보였다. 이와 같은 에너지 대사율 평가시스템은 연속적이고 반복적인 실제 농작업 자세 부하를 동적인 상태에서 평가할 수 있을 뿐 만 아니라 산소소비량 측정기와 같은 추가적인 장비가 필요하지 않아 현장 적용성이 뛰어 날 것으로 기대된다.
Quasi-stiffness of the knee joint in flexion and extension during the golf swing.
Choi, Ahnryul,Sim, Taeyong,Mun, Joung Hwan E. F.N. Spon Ltd 2015 Journal of Sports Sciences Vol.33 No.16
<P>Biomechanical understanding of the knee joint during a golf swing is essential to improve performance and prevent injury. In this study, we quantified the flexion/extension angle and moment as the primary knee movement, and evaluated quasi-stiffness represented by moment-angle coupling in the knee joint. Eighteen skilled and 23 unskilled golfers participated in this study. Six infrared cameras and two force platforms were used to record a swing motion. The anatomical angle and moment were calculated from kinematic and kinetic models, and quasi-stiffness of the knee joint was determined as an instantaneous slope of moment-angle curves. The lead knee of the skilled group had decreased resistance duration compared with the unskilled group (P?<?0.05), and the resistance duration of the lead knee was lower than that of the trail knee in the skilled group (P?<?0.01). The lead knee of the skilled golfers had greater flexible excursion duration than the trail knee of the skilled golfers, and of both the lead and trail knees of the unskilled golfers. These results provide critical information for preventing knee injuries during a golf swing and developing rehabilitation strategies following surgery.</P>
Choi, Ahnryul,Sim, Taeyong,Mun, Joung Hwan Informa UK (TaylorFrancis) 2016 Journal of Sports Sciences Vol.34 No.10
<P>Golf requires proper dynamic balance to accurately control the club head through a harmonious coordination of each human segment and joint. In this study, we evaluated the ability for dynamic balance during a golf swing by using the centre of mass (COM)-centre of pressure (COP) inclination variables. Twelve professional, 13 amateur and 10 novice golfers participated in this study. Six infrared cameras, two force platforms and SB-Clinic software were used to measure the net COM and COP trajectories. In order to evaluate dynamic balance ability, the COM-COP inclination angle, COM-COP inclination angular velocity and normalised COM-COP inclination angular jerk were used. Professional golfer group revealed a smaller COM-COP inclination angle and angular velocity than novice golfer group in the lead/trail direction (P<0.01). In the normalised COM-COP inclination angular jerk, the professional golfer group showed a lower value than the other two groups in all directions. Professional golfers tend to exhibit improved dynamic balance, and this can be attributed to the neuromusculoskeletal system that maintains balance with proper postural control. This study has the potential to allow for an evaluation of the dynamic balance mechanism and will provide useful basic information for swing training and prevention of golf injuries.</P>
Quantifying coordination between agonist and antagonist muscles during a gait
Hak-Je Yoo,Taeyong Sim,Ahn Ryul Choi,Hyun-Joon Park,Heegoo Yang,Hyun Mu Heo,Kum Sook Park,Joung Hwan Mun 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11
Ankle joint provides propulsion and stability of the gait through coordination of agonist and antagonist muscles. The main goal of this study is to quantify the coordination of the ankle joint agonist and antagonist muscles during a gait. For this, we introduce a Vector cording technique (VCT) that has not previously been applied in EMG signal quantification and validate its feasibility. EMG signals of the muscles were acquired during normal gait (n = 15). By applying two muscle EMG signals in the VCT method, muscle activation could be categorized into 4 patterns of In- (First phase = 1.3±0.5%; Second phase = 6.9±1.5%), Anti- (First phase = 1.6±0.6%; Second phase = 11.9±1.1%), Tibialis anterior- (First phase = 8.1±0.6%; Second phase = 9.1±1.5%), and Medial gastocnemius- (First phase = 1.4±0.5%;Second phase = 22.1±2.2%) activations. This categorization allows us to quantify the relative activation between two muscles and the activation of each muscle over time.
( Dongjune Lee ),( Seung Eel Oh ),( In Kwang Lee ),( Taeyong Sim ),( Su Bin Joo ),( Hyun Joon Park ),( Joung Hwan Mun ) 한국농업기계학회 2015 바이오시스템공학 Vol.40 No.3
Purpose: From the perspective of biomechanics, joint moments quantitatively show a subject’s ability to perform actions. In this study, the effect of normalization in the fast and asymmetric motions of a golf swing was investigated by applying three different normalization methods to the raw joint moment. Methods: The study included 13 subjects with no previous history of musculoskeletal diseases. Golf swing analyses were performed with six infrared cameras and two force plates. The majority of the raw peak joint moments showed a significant correlation at p < 0.05. Additionally, the resulting effects after applying body weight (BW), body weight multiplied by height (BWH), and body weight multiplied by leg length (BWL) normalization methods were analyzed through correlation and regression analysis. Results: The BW, BWH, and BWL normalization methods normalized 8, 10, and 11 peak joint moments out of 18, respectively. The best method for normalizing the golf swing was found to be the BWL method, which showed significant statistical differences. Several raw peak joint moments showed no significant correlation with measured anthropometrics, which was considered to be related to the muscle coordination that occurs in the swing of skilled professional golfers. Conclusions: The results of this study show that the BWL normalization method can effectively remove differences due to physical characteristics in the golf swing analysis.
Chihun In,Jungmok Seo,Hyukho Kwon,Jeongmook Choi,Sangwan Sim,Jaeseok Kim,Taeyong Kim,Taeyoon Lee,Hyunyong Choi IEEE 2015 IEEE transactions on terahertz science and technol Vol.5 No.4
<P>The surface-trap mediated carrier recombination is a crucial feature in characterizing the optoelectronic properties of nanowires (NWs). Due to the one-dimensional characteristics, the photoexcited carriers experiences multiple carrier interactions in the transverse direction such that strong carrier-carrier interactions are expected to play an important role in the NW carrier recombination. Here, using ultrafast optical-pump and terahertz-probe spectroscopy, we show that the Auger scattering significantly reduces the trap-mediated decay process. Systematic studies on bulk Si, bundled, individual, and encapsulated (reduced surface-trap density) SiNWs reveal that the effect of Auger recombination exhibits strong pump-fluence dependence depending on the surface-treatment condition.</P>
Lee, Dongjune,Oh, Seung Eel,Lee, In-Kwang,Sim, Taeyong,Joo, Su-bin,Park, Hyun-Joon,Mun, Joung Hwan Korean Society for Agricultural Machinery 2015 바이오시스템공학 Vol.40 No.3
Purpose: From the perspective of biomechanics, joint moments quantitatively show a subject's ability to perform actions. In this study, the effect of normalization in the fast and asymmetric motions of a golf swing was investigated by applying three different normalization methods to the raw joint moment. Methods: The study included 13 subjects with no previous history of musculoskeletal diseases. Golf swing analyses were performed with six infrared cameras and two force plates. The majority of the raw peak joint moments showed a significant correlation at p < 0.05. Additionally, the resulting effects after applying body weight (BW), body weight multiplied by height (BWH), and body weight multiplied by leg length (BWL) normalization methods were analyzed through correlation and regression analysis. Results: The BW, BWH, and BWL normalization methods normalized 8, 10, and 11 peak joint moments out of 18, respectively. The best method for normalizing the golf swing was found to be the BWL method, which showed significant statistical differences. Several raw peak joint moments showed no significant correlation with measured anthropometrics, which was considered to be related to the muscle coordination that occurs in the swing of skilled professional golfers. Conclusions: The results of this study show that the BWL normalization method can effectively remove differences due to physical characteristics in the golf swing analysis.