• Structural Engineering and Mechanics
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• 제71권3호
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• pp.245-255
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• 2019

In this paper, an inverted-pendulum model consisting of a point supported by spring limbs with roller feet is adopted to simulate human walking load. To establish the kinematic motion of first and second single and double support phases, the Lagrangian variation method was used. Given a set of model parameters, desired walking speed and initial states, the Newmark-${\beta}$ method was used to solve the above kinematic motion for studying the effects of roller radius, stiffness, impact angle, walking speed, and step length on the ground reaction force, energy transfer, and height of center of mass transfer. The numerical simulation results show that the inverted-pendulum model for walking is conservative as there is no change in total energy and the duration time of double support phase is 50-70% of total time. Based on the numerical analysis, a dynamic load factor ${\alpha}_{wi}$ is proposed for the traditional walking load model.

• 한국정밀공학회지
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• 제20권6호
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• pp.230-237
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• 2003

On this study, we operated the dynamic response for impact load of impact absorbing system for spreader by the finite element analysis and showed respectively the spring constant and the damping coefficient which the reaction force by impact was the lowest value for three types impact absorbing system according to the change of system, also we presented the change of impact reaction force according to the spring constant and the damping coefficient. Additionally, among the three types impact absorbing system according to the change of system, the reaction force of model II was the lowest value and the next model which has higher value than model II was model Iand model III has the highest value in the three types.

• International journal of advanced smart convergence
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• 제9권4호
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• pp.26-33
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• 2020

This study measured the downward stepping movement relative to weight change (no load, and 10%, 20%, 30% of body weight respectively of adult male (n=10) from standardized stair (rise of 0.3 m, tread of 0.29 m, width of 1 m). The 3-dimensional cinematography and ground reaction force were also utilized for analysis of leg stiffness: Peak vertical force, change in stance phase leg length, Torque of whole body, kinematic variables. The strategy heightened the leg stiffness and standardized vertical ground reaction force relative to the added weights (p<.01). Torque showed rather larger rotational force in case of no load, but less in 10% of body weight (p<.05). Similarly angle of hip joint showed most extended in no-load, but most flexed in 10% of body weight (p<.05). Inclined angle of body trunk showed largest range in posterior direction in no-load, but in vertical line nearly relative to added weights (p<.001). Thus the result of the study proved that downward stepping strategy altered from height of 30 cm, regardless of added weight, did not affect velocity and length of lower leg. But added weight contributed to more vertical impulse force and increase of rigidity of whole body than forward rotational torque under condition of altered stepping strategy. In future study, the experimental on effect of weight change and alteration of downward stepping strategy using ankle joint may provide helpful information for development of enhanced program of prevention and rehabilitation on motor performance and injury.

• International Journal of Automotive Technology
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• 제1권1호
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• pp.56-60
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• 2000

The customers demand of a good vehicle agility consists of a quick reaction of the vehicle with the actuation of the throttle pedal on one hand and a high comfort level of vibration and noise within the vehicle on the other hand, which means the reduction of disturbing side effects. In order to achieve a satisfactory compromise it is necessary to gain a deeper understanding of the complex, high dynamic vibrations system "vehicle / drive train". For several years the ika has been carrying out such detailed vehicle investigations and test bench measurements in addition to comprehensive CAE analysis for various research projects in partnership with different vehicle manufacturers.

• 대한인간공학회지
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• 제28권3호
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• pp.41-47
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• 2009

The purpose of this study, during the lifting task was researching the difference and a relationship between the ground reaction force and the grip strength by change of position. After grip strength has measured in symmetry position and asymmetry position at 45cm and 75cm of height of hand, ground reaction force was measured by same attitude lifting wooden box. We analyzed the difference of grip strength and ground reaction force in each position change. The results of grip strength, the grip strength of both hand were significant difference that in study subject symmetry and asymmetry position (p<0.01). The results of symmetry lifting task, the study subjects was significant difference of the ground reaction force difference by height (p<0.05). Asymmetry lifting task was significant difference of ground reaction force difference by direction of rotation was changed (p<0.01). The result of it will rotate with non-dominant hand side of lifting tasks from height 75cm where it easily maintains a balance possibility and decreasing the load of the hand. Therefore, from the workshop in the work people, it will be between the height 75cm and non-dominant hand side of trunk rotatory direction in the lifting tasks. Future study is necessary researched about the change of grip strength when the height of the hand is higher, and the difference of the ground reaction force when the change of weight.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2002년도 추계공동학술대회논문집
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• pp.161-167
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• 2002

Cai-go management facility of harbor are required an expansion due to increase of cargo quantity. Design technology of Yard AGV call be possible to deal many cargo rapidly and accurately. So it is produced a profit about cal-go management. This study is presented optimum of suspension parameter for design technology Yard AGV. Model I, II are modeled about Initial of container weight, height. When the maximum stroke of suspension is 0.26m, optimum is achieved to reduce the reaction force at the minimum. Also, the reaction force is study to become stability in I second. A change of spring constant and coefficient of damper make change the reaction force and minimum reaction force appear in optimum value. All modeling and analysis are used combination. contact element of Ansys program.

• 대한인간공학회지
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• 제4권2호
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• pp.17-24
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• 1985

To compare heart rate, $O_2$ uptake, $Vo_2$ ($O_2$ consumption), blood pressure (systolic, diastolic), reaction time, stability, flicker fusion value during 4 load levels with Rs (self-paced respiration) and Rp (paced respiration), 4 subjects participated in this experiment 1 hour/day, 6 days/week for 9 weeks. The cycle of Rp is 6 sec. (inspiration: 3 sec. & expiration: 3 sec.) Implications of the results are discussed in terms of the change in the physiological responses and human performance by the respiratory pattern. The results are as follows, 1. The changing magnitude of heart rate with Rp was larger than with Rs and the variance during load level 4 was significant. 2. The $Vo_2$ with Rp was smaller than with Rs and maximal $O_2$ uptake given load levels with Rp occurred and for two subjects, it significantly moved from low load level to high load level. 3. The changing magnitude of blood pressure was not consistent but the systolic pressure with Rp was smaller at rest than with Rs. 4. The score of reaction time test and stability test with Rp was better than with Rs.

• 한국항공우주학회지
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• 제42권1호
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• pp.67-75
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• 2014

항우연에서는 복합재 소형항공기(KC-100)에 대하여 15가지 전기체 시험조건과 7개의 국부적 시험조건들에 대한 전기체 정적구조시험을 수행하였다. 시험요구도, 시험일정, 시험체 및 더미구조, 시험하중산출, 시험장치, 시험장비 등을 소개하였다. 수십개의 제어채널을 사용하는 전기체 구조시험의 하중제어의 정확도를 살펴보기 위하여 U1의 시험데이터를 분석하였다. 분석결과 각 채널별 데이터 획득된 하중값은 허용오차인 SNPE(Static null pacing error)값 이내에서 잘 유지하고 있음을 보였고 본 논문의 저자가 제안한 시험의 하중제어오차 크기 정의방법을 적용한 결과 U1 시험의 하중제어 오차값이 8.6N 이었고 나머지 전기체 시험조건들에 대한 시험데이터를 분석한 결과도 보였다. 마지막으로 U1시험에서 자세제어장치에서 측정된 반력들이 시험하중 증가와 함께 변하는 것을 보였고 전기체 구조시험에서 반력변화 발생의 요인들에 대하여 기술하였다.

• 한국인터넷방송통신학회논문지
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• 제23권1호
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• pp.109-116
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• 2023

이 연구의 목적은 계단 내리기 시 성별과 중량차이가 하지역학에 미치는 영향을 분석하는 것이다. 건강한 남성 10 명과 여성 10 명이 참여하였다. 계단 내리기 동작은 중량 변화(체중의 0%, 10%, 20%, 30%)에 따라 영상분석법과 지면반력 시스템을 이용해 분석하였다. 골반의 최대 합성속도에서 성별(남성>여성)과 중량변화(30%, 20%, 10%> 0%)에 따라 서로 차이가 있는 것으로 나타났으며, 성별과 중량 간 상호작용이 나타났다(중량>성별). 계단 내리기 동안 성별의 주효과는 초기 접촉 단계에서 남성보다 여성이 더 감소된 다리길이를 보였다. 또한, 남성보다 여성에게서 더 굴곡된 엉덩, 무릎관절 각도와 발목관절 각도의 저측 굴곡형태가 나타났다. 운동역학 변인에서, 계단 내리기 시 성별의 주효과는 남성보다 여성이 더 증가된 좌우 지면반력과 다리강성을 보였다. 결론적으로 여성들이 계단 내리기 동안 엉덩 관절의 운동 범위와 함께 합성이동속도를 감소시켜 중량을 성공적으로 수용한다는 것을 발견하였다. 반면 남성들은 중량수용과 운동량을 제어하기 위해 좌우 및 수직지면반력, 그리고 다리강성을 더 증가시킨다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.991-994
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• 2017

극초음속 비행체에서는 공기와의 마찰열과 엔진열의 증가로 기체 내부의 열적 부하가 발생한다. 이는 비행체 내부 구조물의 변형을 일으키고 오작동을 발생시킬 수 있다. 흡열연료는 액체 탄화수소 연료로써 흡열반응을 통해 열을 흡수할 수 있는 연료이다. 본 연구에서는 실제 반응조건과 비슷한 Packed bed flow reactor에서 Exo-tetrahydrodicyclopentadiene를 연료로 사용하여 촉매의 흡열량을 측정하는 방법에 대한 연구를 진행하였다.