• Safety and Health at Work
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• 제13권3호
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• pp.315-325
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• 2022

Background: Firefighters are required to carry self-contained breathing apparatus (SCBA), which increases the risk of musculoskeletal disorders. This study assessed the newly recruited firefighters' internal forces and potential musculoskeletal disorders when carrying SCBA. The effects of SCBA strap lengths were also evaluated. Methods: Kinematic parameters of twelve male subjects running in a control condition with no SCBA equipped and three varying-strapped SCBAs were measured using 3D inertial motion capture. Subsequently, motion data and predicted ground reaction force were inputted for subject-specific musculoskeletal modeling to estimate joint and muscle forces. Results: The knee was exposed to the highest internal force when carrying SCBA, followed by the rectus femoris and hip, while the shoulder had the lowest force compared to the no-SCBA condition. Our model also revealed that adjusting SCBA straps length was an efficient strategy to influence the force that occurred at the lumbar spine, hip, and knee regions. Grey relation analysis indicated that the deviation of the center of mass, step length, and knee flexion-extension angle could be used as the predictor of musculoskeletal disorders. Conclusion: The finding suggested that the training of the newly recruits focuses on the coordinated movement of muscle and joints in the lower limb. The strap lengths around 98-105 cm were also recommended. The findings are expected to provide injury interventions to enhance the occupational health and safety of the newly recruited firefighters.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.84-87
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• 2009

Electrowetting is a versatile tool to handle tiny droplets and forms a backbone of digital microfluidics. Numerical analysis is necessary to fully understand the dynamics of electrowetting, especially in designing electrowetting-based devices, such as liquid lenses and reflective displays. We developed a numerical method to analyze the general contact-line problems, incorporating dynamic contact angle models. The method is based on the conservative level set method to capture the interface of two fluids without loss of mass. We applied the method to the analysis of spreading process of a sessile droplet for step input voltages and oscillation of the droplet for alternating input voltages in electrowetting. The result was compared with experimental data. It is shown that contact line friction significantly affects the contact line motion and the oscillation amplitude. The pinning process of contact line was well represented by including the hysteresis effect in the contact angle models.

• 제어로봇시스템학회논문지
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• 제16권9호
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• pp.866-871
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• 2010

Gait analysis is essential for leg diagnosis and rehabilitation for the patients, the handicapped and the elderly. The use of 3D motion capture device for gait analysis is very common for gait analysis. However, this device has several shortcomings including limited workspace, visibility and high price. Instead, we developed gait estimation system using gyroscopes. This system provides gait information including the number of gaits, stride and walking distance. With four gyroscope (one for each leg's thigh and calf) outputs, the proposed gait modeling estimates the movements of the hip, the knees and the feet. Complete pedestrian localization is implemented with gait information and the heading angle estimated from the rate gyro and the magnetic compass measurements. The developed system is very useful for diagnosis and the rehabilitation of the pedestrian at the hospital. It is also useful for indoor localization of the pedestrians.

• 재활복지공학회논문지
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• 제10권1호
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• pp.101-106
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• 2016

본 논문에서는 아마추어 선수들을 대상으로 관성센서 기반의 동작분석 시스템을 이용하여 선수들의 획득 점수와 자세의 관계를 분석하였다. 4명의 13~15세 아마추어 양궁선수들을 대상으로 동작 과정에 대한 가속도를 측정하였으며 각 피실험자는 30미터 거리의 표적을 1엔드 당 6회씩 총 6엔드를 실시하였다. 풀드로우 시의 가속도값을 추출하여 분석한 결과 왼팔의 경우 점수와 팔의 떨림 간에 연관관계를 찾기 어려운 결과를 보이고 있는 반면 오른팔의 경우에 점수가 높을 때 떨림이 큰 결과를 얻었다. 활을 쥐고 있는 좌완이 확실히 고정된 상태에서 우완의 움직임을 통해 조준을 실시하며 조준 시의 미세 조정 기술이 고득점에 기여하는 것으로 유추할 수 있다.

• 한국운동역학회지
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• 제17권4호
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• pp.1-8
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• 2007

The purpose of this study was to investigate the difference in the stride-to-stride variability between two treadmill conditions; traditional treadmill and special treadmill whose speed can be adjusted automatically by subject's walking speed. Eight male subjects (25.1 years, 172.7 cm, 66.6 kg) were participated in treadmill walking experiment. First, preferred walking speed (PWS) of each subject was determined. Second, each subject performed walking experiment with fixed PWS condition and with free PWS condition for 10 minutes. 3D motion capture system (Motion analysis Corp., USA) with 6 cameras was used to collect motion data with sampling frequency of 120Hz. Temporal and spatial variables for stride-to-stride variability were calculated. Coefficient of variance (CV) which quantifies the amount of variability and Detrended Fluctuation Analysis (DFA) which explains the structure (self-similarity) of the variability were used for analysis. Results showed that the amount of variability during free PWS condition was greater than that of fixed PWS condition. DFA results showed that there was a statistical difference between two treadmill conditions for the variables of step length, stance time, and double support time. From these results, it is possible that traditional treadmill study might give incorrect conclusion about gait variability study. Further study is necessary to clarify these matters by considering the number of subjects, experimental time, and gait variables for the study of stride-to-stride variability.

• 만화애니메이션 연구
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• 통권28호
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• pp.125-153
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• 2012

본고는 무빙이미지에서 모션의 양태성 전략이 매체나 장르에 어떤 변화를 가져오는지에 관한 연구이다. 오늘날 모션의 양태성은 애니메이션 뿐만 아니라 영화에서도 적극적으로 조작되는 요소이다. 여기서 모션의 양태성 전략은 일반적으로 장르나 매체에 따라 좌우된다고 말해지는데, 과연 그 명제는 옳은 것인가? 옳다면, 본 명제를 학제적으로 규정되어 있지 않은 '장르 매체'라는 용어를 재고함으로써 좀 더 이론적으로 정리할 수는 없는가? 본고는 그러한 문제를 논의하고자 한다. 본고는 모션의 양태성 조작을 이론적 지평 위에서 바라본다. 맥루한의 핫/쿨미디어 이론과 볼터의 진동이론에서 보면, 궁극적으로 모션 양태성 조작의 효과는 수용자의 감각비율 조작과 같은 것으로 귀결되는데, 이러한 이론적 추론은 사례를 통해 검증될 것이다. 사례 분석에서 본 연구자는 이미지의 모션 양태성 조작이 텍스트 내에서 어떤 효과들을 발현하는 지를 분석하고, 이 효과들이 매체 장르 포지셔닝과 어떤 상관성을 갖는 지를 살펴봄으로써, 본고가 문제시 하는 모션 양태성의 장르 매체 결정론을 평가한다. 결론적으로, 모션의 양태성은 매체의 문제와는 상관없이 장르의 문제에서 결정되는 전략인데, 그 장르는 감각자극의 배합으로 포지셔닝되는 범주라고 할 수 있다. 그렇기 때문에 모션의 양태성 전략은 단위 시퀀스가 필요로 하는 감각성에 좌우된다. 모션의 양태성은 단순히 모션캡처 같이 매체적 측면에서 갖는 기술지향적, 경제적 가치보다 장르적 측면에서 기능성으로 접근해야 하는 전략이다.

• 한국전문물리치료학회지
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• 제27권4호
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• pp.227-232
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• 2020

Background: Hallux valgus (HV) is a foot deformity developed by mediolateral deviation of the first metatarsophalangeal joint. Although various foot-toe orthoses were used to correct the HV angle, verification of the effects of kinetics variables such as ground reaction force (GRF) through three-dimensional (3D) gait analysis according to the various type of orthoses for HV is insufficient. Objects: This study aimed to investigate the effect of soft and hard types of foot and toe orthoses to correct HV deformity on the GRF in individuals with HV using 3D motion analysis system during walking. Methods: Twenty-six subjects participated in the experiment. Participants had HV angle of more than 15° in both feet. Two force platforms were used to obtain 3D GRF data for both feet and a 3D motion capture system with six infrared cameras was used to measure exact stance phase point such as heel strike or toe off period. Total walk trials of each participant were 8 to 10, the walkway length was 6 m. Two-way repeated measures ANOVA was used to determine the effects of each orthosis condition on the various GRF values. Results: The late anteroposterior maximal force and a first vertical peak force of the GRF showed that the hard type orthosis condition significantly increased GRF compared to the other orthosis conditions (p < 0.05). Conclusion: There were significant effects in GRF values when wearing the hard type foot orthosis. However, the hard type foot orthosis was uncomfortable to wear during walking. Therefore, it is necessary to develop a new foot-toe orthosis that can compensate for these disadvantages.

• Annals of Rehabilitation Medicine
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• 제42권6호
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• pp.872-883
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• 2018

Objective To replace camera-based three-dimensional motion analyzers which are widely used to analyze body movements and gait but are also costly and require a large dedicated space, this study evaluates the validity and reliability of inertial measurement unit (IMU)-based systems by analyzing their spatio-temporal and kinematic measurement parameters. Methods The investigation was conducted in three separate hospitals with three healthy participants. IMUs were attached to the abdomen as well as the thigh, shank, and foot of both legs of each participant. Each participant then completed a 10-m gait course 10 times. During each gait cycle, the hips, knees, and ankle joints were observed from the sagittal, frontal, and transverse planes. The experiments were conducted with both a camera-based system and an IMU-based system. The measured gait analysis data were evaluated for validity and reliability using root mean square error (RMSE) and intraclass correlation coefficient (ICC) analyses. Results The differences between the RMSE values of the two systems determined through kinematic parameters ranged from a minimum of 1.83 to a maximum of 3.98 with a tolerance close to 1%. The results of this study also confirmed the reliability of the IMU-based system, and all of the variables showed a statistically high ICC. Conclusion These results confirmed that IMU-based systems can reliably replace camera-based systems for clinical body motion and gait analyses.

• Coupled systems mechanics
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• 제7권2호
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• pp.111-139
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• 2018

A successful methodology for modelling controlled destruction and progressive collapse of 2D reinforced concrete frames is presented in this paper. The strategy is subdivided into several aspects including the failure mechanism creation, and dynamic motion in failure represented with multibody system (MBS) simulation that are used to jointly capture controlled demolition. First phase employs linear elasto-plastic analysis with isotropic hardening along with softening plastic hinge concept to investigate the complete failure of structure, leading to creation of final failure mechanism that behaves like MBS. Second phase deals with simulation and control of the progressive collapse of the structure up to total demolition, using the nonlinear dynamic analysis, with conserving/decaying energy scheme which is performed on MBS. The contact between structure and ground is also considered in simulation of collapse process. The efficiency of the proposed methodology is proved with several numerical examples including six story reinforced concrete frame structures.

• 한국운동역학회지
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• 제31권1호
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• pp.44-49
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• 2021

Objective: The purpose of this study was to analyze kinematic variables according to ground slope angle during golf putting. Method: 26 collegiate golfers (age: 22.54±2.15 kg, height: 174.64±6.07 cm, weight: 71.35±9.27 kg, handicap: 5.11±4.50) were participated, and 8 motion capture cameras (250 Hz), Nexus, and Kwon3DXP software were used to collect data. It was performed repeated measures ANOVA and Bonferroni adjustment. Alpha set at .05. Results: Body alignments were not significantly different at address. Putter head trajectory and loft angle were significantly different, and AP direction of acceleration of putter head was significantly different. However, ML and SI direction of acceleration of putter head were not significantly different. Conclusion: Therefore, it was identified that ground slope angle was affected the kinematic variables during putting, and it will be performed that correlation analysis between putting success rate and kinematic variables according to ground slope angle during golf putting.