• 한국운동역학회지
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• 제15권1호
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• pp.259-274
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• 2005

The purpose of this study was to compare the kinematic and kinetic parameters of lower extremity joints between novice and experienced sports aerobic dancers during two heights of depth jumps. Four male dancers were participated in this study and they performed 40cm and 60cm height depth jump three times, respectively. Four ProReflex MCU cameras (100frame/sec) and a Kistler force plate (1000Hz) were used for data collection. The results indicated that the duration of contact phase of experienced group was shorter than that of novice group regardless of jump height. For minimum angle of hip, knee, and ankle joints, the novice group had tendency to decrease the angle but the experienced group had increased the joint angle with jump height. There was no difference of total ground reaction force between the groups but the reaction force had tendency to increase with jump height. Thus, this study implied that repetition of jump and landing may induce joint related injury and further study such as. EMG analysis of lower extremity can be needed to verify the relationship between injury and ground reaction force.

• 한국산업융합학회 논문집
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• 제19권1호
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• pp.18-30
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• 2016

In this paper, we propose a new technique to the design and real-time control of an adaptive controller for robotic manipulator based on digital signal processors. The Texas Instruments DSPs(TMS320C80) chips are used in implementing real-time adaptive control algorithms to provide enhanced motion control performance for dual-arm robotic manipulators. In the proposed scheme, adaptation laws are derived from model reference adaptive control principle based on the improved Lyapunov second method. The proposed adaptive controller consists of an adaptive feed-forward and feedback controller and time-varying auxiliary controller elements. The proposed control scheme is simple in structure, fast in computation, and suitable for real-time control. Moreover, this scheme does not require any accurate dynamic modeling, nor values of manipulator parameters and payload. Performance of the proposed adaptive controller is illustrated by simulation and experimental results for a dual arm robot manipulator with eight joints. joint space and cartesian space.

• 한국산업융합학회 논문집
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• 제24권6_2호
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• pp.883-890
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• 2021

In this study, joint analysis was conducted on the rock slope by aerial surveying using UAV. Aerial photos were taken using UAV to measure the directionality of the rock slope exposed to the site, and the directionality of the joint was analyzed using the photographed photos. UAV photography was taken under conditions of 90% overlap and an altitude of 50m. The photographing path was measured in the horizontal, vertical, and oblique directions based on the slope, and the joint characteristics were analyzed. Aerial surveying research on the joint directionality analysis of rock slopes is still incomplete, and the method for accurate joint directionality analysis is not presented strategically, so it is difficult to apply it in design. Through the results of this study, we would like to propose an flight photographing technique for the investigation of rock joints. As a result of the study, in the case of the joint investigation of the rock slope using UAV, it was necessary to change conditions such as altitude, aerial photography route, and overlap according to the size of the joint according to the site conditions.

• Computers and Concrete
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• 제23권2호
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• pp.97-106
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• 2019

This paper describes the design of a new interlocking masonry system, the production of designed interlocking units and mechanical properties of interlocked masonry assemblages with mortar. In this proposed system, units have horizontal and vertical locks to integrate the units to the wall and have a channel to enable the use of horizontal reinforcements in the wall. Using these units, unfilled, filled or reinforced walls can be constructed with or without mortar. In the production of the interlocking units, it was decided to use foamed concrete. 12 trial productions have been carried out at different mix proportions to obtain the optimum concrete mix. At the end of the mentioned productions, the units were produced with foam concrete which is selected as the most suitable in terms of compressive strength and specific gravity. Then, axial compression, diagonal tension and bed joint shear tests were carried out to determine the mechanical properties of the interlocked masonry assemblages with mortar. Results from the tests showed that interlocks designed to strengthen the system against shear stresses by creating discontinuity throughout the joints have been successful to achieve their aim. Obtained data will enable structural analysis of walls to be constructed with these new units.

• Structural Engineering and Mechanics
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• 제77권3호
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• pp.383-394
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• 2021

Column foot in traditional Chinese timber structures may be subjected to be uplifted due to the lateral load and subsequently reset under the vertical loads. The residual moment of the rocking column foot is the most important parameter representing the mechanical behaviors of column foot, and the simplification of joints is the basis of structural analysis of whole structure. The complicated mechanical behaviors of joint and the modeling of the column foot joint has been undertaken historically based on the experiments and numerical simulation. On the condition of limited application range of those models, a lack of simplified model to represent the mechanical behaviors of joint deserves attentions. There is a great need to undertake theoretical studies to derive the residual moment and make better simplified model of the joint. This paper proposes the residual moment and equivalent simplified model of the rotational stiffness for column foot joint. And, the timber frame is established based on the simplified model, which is verified by solid finite element model. Results show that a mutual agreement on the mechanical behaviors of the timber frame is obtained between the simplified model and the solid finite element model. This study can serve as the references of the structural analysis for the traditional timber structures.

• Structural Monitoring and Maintenance
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• 제7권4호
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• pp.295-317
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• 2020

Investigation of the stability of arch dam abutments is one of the most important aspects in the analysis of this type of dams. To this end, the Bakhtiari dam, a doubly curved arch dam having six wedges at each of its abutments, is selected. The seismic safety of dam abutments is studied through time history analysis using the design-based earthquake (DBE) and maximum credible earthquake (MCE) hazard levels. Londe limit equilibrium method is used to calculate the stability of wedges in abutments. The thrust forces are obtained using ABAQUS, and stability of wedges is calculated using the code written within MATLAB. Effects of foundation flexibility, grout curtain performance, vertical component of earthquake, nonlinear behavior of materials, and geometrical nonlinearity on the safety factor of the abutments are scrutinized. The results show that the grout curtain performance is the main affecting factor on the stability of the abutments, while nonlinear behavior of the materials is the least affecting factor amongst others. Also, it is resulted that increasing number of the contraction joints can improve the seismic stability of dam. A cap is observed on the number of joints, above which the safety factor does not change incredibly.

• Computers and Concrete
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• 제29권2호
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• pp.69-79
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• 2022

For long underground box utility tunnels, post-tensioned precast concrete is often used. Between precast tunnel segments, sealed waterproof flexible joints are often specified. Fault displacement can lead to excessive deformation of the joints, which can lead to reduction in waterproofing due to diminished contact pressure between the sealant strip and the tunnel segment. This paper authenticates utilization of a finite element model for a prefabricated tunnel fault-crossing founded on ABAQUS software. In addition, material parameter selection, contact setting and boundary condition are reviewed. Analyzed under normal fault action are: the influence of fault displacement; buried depth; soil friction coefficient, and angle of crossing at the fault plane. In addition, distribution characteristics of the utility tunnel structure for vertical and longitudinal/horizontal relative displacement at segmented interface for the top and bottom slab are analyzed. It is found that the effect of increase in fault displacement on the splice joint deformation is significant, whereas the effects of changes in burial depth, pipe-soil friction coefficient and fault-crossing angle on the overall tunnel and joint deformations were not so significant.

• 한국강구조학회 논문집
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• 제29권6호
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• pp.411-422
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• 2017

본 연구에서는 콘크리트피복 원형충전강관 기둥을 적용한 합성구조 접합부의 거동특성과 내진성능을 평가하기 위하여, 기둥-플랜지 접합부에 대한 인장실험과 보-기둥 접합부에 대한 반복하중 실험을 수행하였다. 기둥-플랜지 인장실험은 피복콘크리트의 유무와 플랜지 폭, 인장철근 보강을 변수로 하여 5개의 실험체에 대하여 하중재하능력과 파괴모드를 분석하였다. 실험결과, 접합부에서의 플랜지 단부 폭을 200mm에서 350mm로 증가시킬 경우 연결부의 강도 및 강성이 각각 1.61배와 1.56배가 증가했고, 인장철근을 보강할 경우 추가적으로 강성과 강도가 각각 1.35배와 1.92배 증가했다. 접합부 반복하중 실험에서는 접합 상세를 변수로 3개의 외부접합부 실험체를 구성했다. 접합부 보강상세로는 인장철근 보강과 강관의 두께, 수직강판 보강을 고려하였다. 모든 접합부 실험체는 보에서 뚜렷한 휨항복이 발생하였으며 접합부의 손상은 제한적이었다. 특히, 강재보가 강관에 직접 용접되는 경우 보의 웨브를 통해서도 하중이 전달되기 때문에, 플랜지 인장실험 결과보다 보수적인 설계가 가능하며, 접합부 강관 두께를 증가시키거나 수직강판으로 보강한 경우에는 추가적으로 패널존의 전단내력이 증가하는 것으로 나타났다.

• 대한토목학회논문집
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• 제35권1호
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• pp.129-139
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• 2015

차수기능을 점토 코아 대신 상류사면의 콘크리트 슬래브로 수행하는 콘크리트 표면차수벽형 석괴댐의 설계는 이론보다는 사례와 경험에 크게 의존한다. 본 연구에서는 두 개의 CFRDs에서 준공 후 초기 담수기간에 계측된 데이터를 근거로 콘크리트 슬래브와 누수량 거동을 분석하였다. 분석결과 슬래브의 변형률과 수직이음부의 수평변위는 미미하게 계절적인 온도 변화와 저수위면 증가에 의한 담수하중의 영향을 받고, 주변이음부의 변형은 온도 변화의 영향은 미미하고 담수하중의 영향을 크게 받는 것으로 나타났다. 그리고 누수량은 담수하중에 따른 주변이음부의 변형에 의한 영향을 크게 받는 것으로 나타났다.

• 한국강구조학회 논문집
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• 제9권2호통권31호
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• pp.237-248
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• 1997

크레인 주행거더에서 빈번히 발생되는3 종류의 균열을 재현하기 위해서 거더 길이 640 mm, 높이 600 mm, 폭 300 mm의 시험체 2기를 제작하여 피로실험을 수행하였다. 시험체의 균열은 재하점 부근과 가세트 단부 및 하부플랜지와 웨브의 모살용접부에서 발생하였다. 재하점 근방의 균열은 수직보강재가 위치한 상부플랜지와 웨브 사이의 모살용접부에서 발생해서 웨브의 대각선 방향으로 진전하였다. 또한 하부플랜지 종비드에서 발생된 균열은 주행거더방향에 수직으로 성장하였다. 크레인 주행거더의 각 부위의 피로등급은 JSSC 피로설계지침의 피로등급과 비교해 보면, 재하점 근방의 모살용접부는 E 등급, 가세트 단부는 G 또는 H 등급, 하부플랜지 종비드 부위는 D 등급 정도로 나타났다. 가세트 단부와 종비드 부위는 피로설계지침과 잘 일치하고 있음을 알 수 있다.