• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.381-386
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• 2010

This study examined the changes in the walking pattern during level walking under low illumination conditions. Fourteen male subjects ($22.1{\pm}2.21$ years, $174{\pm}3.74\;cm$, $68.86{\pm}10.81\;kg$) with normal vision and no disabilities were enrolled in this study. All experiments were performed on a level walkway with three conditions: normal walking (preferred & low speed) and walking with low illumination. 3D motion capturing system was used for acquisition and analysis of the walking motion data with a sampling frequency of 120Hz. The walking speed, normalized jerk(NJ) at the center of mass(COM), wrist and heel, knee and elbow joint angle, ratio of the knee joint angle to elbow joint angle and the toe clearance on stance phase were used to compare the differences in walking pattern between the two illumination conditions, The results showed that the walking speed and joint angles decreased in low illumination, whereas the NJ and toe minimum clearance increased. In low illumination, most variables were similar to effects of low speed walking, but toe clearance was different from the effects of low speed. These results can be used as primary data for examining the changes in the level walking pattern of young adults under low illumination. Further study will be needed to compare these results in young adults with those in the elderly.

• Journal of the Korean Society of Safety
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• v.34 no.5
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• pp.132-138
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• 2019

Fall accident is the most frequent accident type of occupational accidents. As the age of workers increases, trip and fall accident increases more than other types of occupational accident in the middle-aged group. In this study, the gait characteristics of 25 middle-aged participants (mean ages 47.4, S.D. 5.8) were studied to analyze the trip and fall risks. The Minimum toe clearance(MTC) against the floor surface was measured in the variable conditions of gait speed by a motion capture system. In the 50s age group, the MTC decreased and the MTC tended to reduce the variation with increasing walking speed in the level walking. Therefore, the trip and fall risks for the 50s age group is higher than the 40s age group. Especially, the faster walking speed will increase the trip and fall risks even more.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.1
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• pp.88-94
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• 1998

Installation design methods and results of an aircraft engine on the wing-mounted-nacelle type aircraft has been presented in this paper. The design process starts from design requirements and constraints and covers some major aspects of the engine installation design such as wing-nacelle interference drag, roll clearance, ground clearance, nose gear collapse margin, rotor burst and fuel tank capacity. The method was applied to 100-seat class airplane(K100). Results of the design suggest optimum nacelle location and nacelle installation angle(toe-in, incidence, droop angle) which satisfies in stalled engine performance and size/location of wing dry day.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.193-195
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• 2006

In this study, we developed an active controlled ankle-foot orthosis(AAFO) which can control the dorsiflexion/plantarflexion of the ankle joint during gait to prevent foot drop and toe drag for paralysis patients. To prevent dropping foot after heel strike, ankle joint was actively controlled to minimize forefoot collision with the ground. It was also controlled to provide toe clearance and to help push-off during late stance. The 3D gait analysis was performed on two healthy subjects equipped with the developed AAFO to compare with the normal gait and the conventional AFO gait. In the developed AAFO gait, differently from the conventional AFO gait, significant push-off was observed during pre-swing and the maximum flexion moment during pre-swing phase was similar to that of normal gait. A remarkable dorsiflexion also occurred during initial swing. These results indicated that the developed AAFO could have certain clinical benefits to prevent foot drop for paralysis patients, compared to conventional AFOs.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.04a
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• pp.4-4
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• 1998

이 연구에서는 100인승 항공기 급의 저익-주익장착나셀(wing mounted nacelle)의 추진기관 장착설계 방법을 제시하였다. 장착설계 방법을 구체적으로 설명하기 위해 세부적인 설계제한조건(design constraint)과 설계요구조건(design requirement and objectives)을 정의하고, 그러나 기준을 근거로 실례의 항공기(K100)를 사용하여 주익장착방식의 장착설계를 수행하였다. 장착설계는 간접항력(interference drag), roll clearance, ground clearance, nose gear collapse margin, rotor burst, 연료탱크용량 등의 설계제한 사항들을 고려하여 엔진성능을 만족시킬 수 있는 최적의 나셀 장착위치(spanwise, FS, WL)와 장착각도(toe-in, incidence, droop angle), wing day의 위치와 크기를 결정하여 향후에 개발될 주익장착방식의 추진기관 장착설계에 활용될 수 있는 설계절차를 구축하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.471-479
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• 2015

This study examined the effects of smart phone use while young adults negotiated an obstacle (2 cm high). Seventy-four young adults (mean age: $23.76{\pm}3.17years$, age range: 20-27 years) participated in the study. They were allocated randomly into two groups; smart phone group and no smart phone group. The smart phone group negotiated an obstacle while simultaneously using a smart phone at a self-paced speed whereas the no smart phone group negotiated an obstacle with no special option. A motion analysis system were used to measure the gait parameters, such as toe clearance, cadence, step length, step width, stride length, and walking velocity in two groups. The toe clearance, and step-width, cadence, and step-length were significantly greater for the smart phone group than the no smart phone group (p<.05) and the walking velocity was significantly lower in the smart phone group (p<.05). On the other hand, there was no significant difference in the stride length between the two groups. This study suggests that smart phone use degrades the obstacle avoidance abilities of healthy young adults, which may increase risk of falls.

• Korean Journal of Applied Biomechanics
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• v.18 no.2
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• pp.11-17
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• 2008

Falls associated with tripping over an obstacle can be dangerous, yet little is known about the strategies used for stepping over obstacles by Parkinson's patients. The purpose of this study was to investigate stepping over gait characteristics according to obstacle height in Parkinson's patients. The gait of 7 Parkinson's patients was examined during a 5.0 m approach to, and while stepping over, obstacles of 0, 2.5, 5.2, and 15.2 cm. Only five Parkinson's patients were able to clear all obstacles successfully; as such, only their data were analyzed. A one-way ANOVA for repeated measures was employed for selected kinematic variables to analyze the differences of the height of four obstacles. The results showed significant differences between obstacle height and: approaching speed (AS), foot clearance from the obstacle(FC), and step width (SW). The results showed no significant differences between obstacle height and: crossing speed (CS), toe distance (TD), and heel distance (HD). This strategy tends to reduce the risk of toe contact with the obstacle. Parkinson's patients were stepping over the obstacle slowly, stably and inefficiently.

• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.161-166
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• 2016

Objective: The purpose of this study was to determine the knee and ankle joint kinematics and kinetics by comparing downhill walking with valley-shape combined slope walking. Method: Eighteen healthy men participated in this study. A three-dimensional motion capture system equipped with eight infrared cameras and a synchronized force plate, which was embedded in the sloped walkway, was used. Obtained kinematic and kinetic parameters were compared using paired two-tailed Student's t-tests at a significance level of 0.05. Results: The knee flexion angle after the mid-stance phase, the mean peak knee flexion angle in the early swing phase, and the ankle mean peak dorsiflexion angle were greater during downhill walking compared with valley-shape combined slope walking (p < 0.001). Both the mean peak vertical ground reaction force (GRF) in the early stance phase and late stance phase during downhill walking were smaller than those values during valley-shape combined slope walking. (p = 0.007 and p < 0.001, respectively). The mean peak anterior GRF, appearing right after toe-off during downhill walking, was also smaller than that of valley-shape combined slope walking (p = 0.002). The mean peak knee extension moment and ankle plantar flexion moment in late stance phase during downhill walking were significantly smaller than those of valley-shape combined slope walking (p = 0.002 and p = 0.015, respectively). Conclusion: These results suggest that gait strategy was modified during valley-shape combined slope walking when compared with continuous downhill walking in order to gain the propulsion for lifting the body up the incline for foot clearance.

• Physical Therapy Korea
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• v.9 no.4
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• pp.1-11
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• 2002

본 연구의 목적은 이중과업 방법론(dual task methology)을 사용해서 젊은 사람과 노인을 대상으로 독립된 두 사건(two separate concurrent events)을 동시에 수행하는데 요구되는 주의력에 대한 분석과 노인에서의 특징적 차이를 찾는 것이다. 본 실험은 대상자가 힘판(force plate) 위에서 장애물(10cm) 보행시에 경피자극(cutaneous stimulation)에 대하여 마이크로 스위치(micro-switch)를 사용하여 반응하면서 시행되었다. 힘판과 시간(temporal events) 그리고 반응시간(reaction time)에 관한 자료들은 1000 Hz의 주파수로 수집되었다. 반응시간은 대상자들이 서 있는 상태(baseline) 장애물 보행시(dual task)에서 수집되었다. 반응시간은 아중과업 조건에서 대상자 모두에게서 긴 것으로 나타났으며 특히 노인에서 정상 성인보다 반응시간이 긴 것으로 나타났다. 이중과업 조건 하에서 노인 대상자가 정상 성인에 비해 발가락이 장애물에 닫지 않고 통과할 수 있는 공간, 즉 토우 클리어런스( toe-clearance)와 슬관전 굴곡(knee flexion) 각도가 훨씬 큰 것으로 나타났다. 이중과업 조건하에서 모든 대상자가 족관절 배측굴곡(ankle dorsiflexion) 각도를 감소시키는 것으로 나타났다. 노인들은 젊은 대상자들보다 훨씬 더 긴(124 ms) 유각시간을 보여 주었으며 정상 장애물 보행시 유각 시간은 이중과업보다 50 ms 긴 것으로 나타났다. 이러한 보행 특성의 차이는 노인대상자들이 젊은 대상자들보다 장애물 보행시에 이중과업의 영향을 더 받았기 때문인 것으로 판단된다. 이중 과업 시행시 이러한 토우 클리어런스의 감소와 장애물 통과시에 보행 속도의 증가는 아마도 낙상의 가능성을 증가시키는 요인이 될 수 있는 것으로 보여진다. 본 연구의 결과는 다중과업(multitasks)을 필요로 하는 보행 훈련 프로그램(gait training program)의 개발과 시행에 있어서 기초적인 자료를 제공할 수 있는 것으로 보여진다.