• Steel and Composite Structures
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• 제21권1호
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• pp.137-156
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• 2016

Due to excellent advantages such as better illuminative effects, considerable material savings and ease and rapidness of construction, the bolted ball-cylinder joint which is a new type joint system has been proposed in space truss structures. In order to reveal more information and understanding on the behaviour of bolted ball-cylinder joints, full-scale experiments on eight bolted ball-cylinder joint specimens were conducted. Five joint specimens were subjected to axial compressive force, while another three joint specimens were subjected to axial tensile force. The parameters investigated herein were the outside diameter of hollow cylinders, the height of hollow cylinders, the thickness of hollow cylinders, ribbed stiffener and axial force. These joint specimens were collapsed by excessive deformation of hollow cylinders, punching damage of hollow cylinders, evulsion of bolts, and weld cracking. The strain distributions on the hollow cylinder opening were mainly controlled by bending moments. To improve the ultimate bearing capacity and axial stiffness of bolted ball-cylinder joints, two effective measures were developed: (1) the thickness of the hollow cylinder needed to be thicker; (2) the ribbed stiffener should be adopted. In addition, the axial stiffness of bolted ball-cylinder joints exhibited significant non-linear characteristics.

• International Journal of Aeronautical and Space Sciences
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• 제17권3호
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• pp.332-340
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• 2016

A design optimization is performed for the double-bolted joint in cylindrical composite structures by using a simplified analytical method. This method uses failure criteria for the major failure modes of the bolted composite joint. For the double-bolted joint with a zigzag arrangement, it is necessary to consider an interaction effect between the bolt arrays. This paper proposes another failure mode which is determined by angle and distance between two bolts in different arrays and define a failure criterion for the failure mode. The optimal design for the double-bolted joint is carried out by considering the interactive net-tension failure mode. The genetic algorithm (GA) is adopted to determine the optimized parameters; bolt spacing, edge distance, and stacking sequence of the composite laminate. A purpose of the design optimization is to maximize the burst pressure of the cylindrical structures by ensuring structural integrity. Also, a progressive failure analysis (PFA) is performed to verify the results of the optimal design for the double-bolted joint. In PFA, Hashin 3D failure criterion is used to determine the ply that would fail. A stiffness reduction model is then used to reduce the stiffness of the failed ply for the corresponding failure mode.

• The Journal of Korean Physical Therapy
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• 제16권2호
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• pp.108-115
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• 2004

The aim of this study is to present the basic reference data of age and specipic gait parameters for comparisons of the gait characteristics depended on Unilateral Trans-Femoral or Trans-Tibial Prostheses. The basic gait parameters were extracted from 10 Adult, 10 above knee(A/K) patients and 10 below knee(B/K) patients, 50 to 60 years of age using VICON 512 Motion Analyzer. The results were as follows; 1) The mean Cadence of the above knee(A/K) patients and below knee(B/K) patients were $87.77{\pm}8.64$ steps/min, to $99.84{\pm}11.14$ steps/min.(p<0.05) 2) The mean Walking Speed of the above knee(A/K) patients and below knee(B/K) patients were $0.84{\pm}0.15$ m/s, to $0.96{\pm}0.25$ m/s.(p>0.05) 3) The mean Stride Length of the above knee(A/K) patients and below knee(B/K) patients were $1.14{\pm}0.14$ m, to $1.14{\pm}0.22$m.(p>0.05) 4) The mean maximal angles of joint on the hip flexion motion for different above knee(A/K) patients and below knee(B/K) patients were $34.75{\pm}10.18_{\circ}$, to $32.32{\pm}6.34_{\circ}$ .(p>0.05) 5) The mean maximal angles of joint on the knee flexion motion for different above knee(A/K) patients and below knee(B/K) patients were $66.97{\pm}15.08_{\circ}$, to $52.65{\pm}9.21_{\circ}$ .(p<0.05) 6) The mean maximal angles of joint on the ankle dorsiflexion motion for different above knee(A/K) patients and below knee(B/K) patients were $14.41{\pm}4.82_{\circ}$, to $10.04{\pm}3.49_{\circ}$ .(p>0.05) 7) The mean maximal angles of joint on the ankle plantarflexion motion for different above knee(A/K) patients and below knee(B/K) patients were $5.77{\pm}3.17_{\circ}$, to $2.75{\pm}4.49_{\circ}$ .(p>0.05)

• Geomechanics and Engineering
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• 제8권3호
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• pp.391-414
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• 2015

In this paper, stabilities of a plane slide rock slope under different hydraulic distributions were studied based on the nonlinear Barton-Bandis (B-B) failure criterion. The influence of various parameters on the stability of rock slopes was analyzed. Parametric analysis indicated that studying the factor of safety (FS) of planar slide rock slopes using the B-B failure criterion is both simple and effective and that the effects of the basic friction angle of the joint (${\varphi}_b$), the joint roughness coefficient (JRC), and the joint compressive strength (JCS) on the FS of a planar slide rock slope are significant. Qualitatively, the influence of the JCS on the FS of a slope is small, whereas the influences of the ${\varphi}_b$ and the JRC are significant. The FS of the rock slope decreases as the water in a tension crack becomes deeper. This trend is more significant when the flow outlet is blocked, a situation that is particularly prevalent in regions with permafrost or seasonal frozen soil. Finally, the work is extended to study the reliability of the slope against plane failure according to the uncertainty from physical and mechanics parameters.

• The Journal of Korean Physical Therapy
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• 제15권3호
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• pp.166-172
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• 2003

The aim of this study is to present the basic reference data of age and specific gait parameters for comparisons of the gait characteristics depended on amputation length of the Unilateral Trans-Tibial Prostheses. The basic gait parameters were extracted from 10 Adult, and 20 below knee(B/K) patients, 50 to 60 years of age using VICON 512 Motion Analyzer. The results were as follows; 1. The mean Cadence of the above knee(A/K) patients and below knee(B/K) patients were $87.77{\pm}8.64$ steps/min, to $99.84{\pm}11.14$ steps/min.(p<0.05) 2. The mean Walking Speed of the above knee(A/K) patients and below knee(B/K) patients were $0.84{\pm}0.15$ m/s, to $0.96{\pm}0.25$ m/s.(p>0.05) 3. The mean Stride Length of the above knee(A/K) patients and below knee(B/K) patients were $1.14{\pm}0.14\;m$, to $1.14{\pm}0.22m$.(p>0.05) 4. The mean maximal angles of joint on the hip flexion motion for different above knee(A/K) patients and below knee(B/K) patients were $34.75{\pm}10.18_{\circ}$, to $32.32{\pm}6.34_{\circ}$.(p>0.05) 5. The mean maximal angles of joint on the knee flexion motion for different above knee(A/K) patients and below knee(B/K) patients were $66.97{\pm}15.08_{\circ}$, to $52.65{\pm}9.21_{\circ}$. (p<0.05) 6. The mean maximal angles of joint on the ankle dorsi-flexion motion for different above knee(A/K) patients and below knee(B/K) patients were $14.41{\pm}4.82_{\circ}$, to $10.04{\pm}3.49_{\circ}$.(p>0.05) 7. The mean maximal angles of joint on the ankle plantar-flexion motion for different above knee(A/K) patients and below knee(B/K) patients were $5.77{\pm}3.17_{\circ}$, to $2.75{\pm}4.49_{\circ}$.(p>0.05)

• 전기학회논문지
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• 제63권3호
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• pp.389-394
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• 2014

Two evolutionary gait generation methods for Cartesian and Joint coordinates space are compared to develop a fast locomotion for quadruped robots. GA(Genetic Algorithm) based approaches seek to optimize a pre-selected set of parameters for the locus of paw and initial position in cartesian coordinates space. GP(Genetic Programming) based technique generate few joint trajectories using symbolic regression in joint coordinates space as a form of polynomials. Optimization for two proposed methods are executed using Webots simulation for the quadruped robot which is built by Bioloid. Furthermore, simulation results for two proposed methods are analysed in terms of different coordinate spaces.

• 한국운동역학회지
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• 제27권1호
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• pp.67-74
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• 2017

Objective: The purpose of this study was to apply a general linear model in statistics to marker position vectors used to study human joint rotational motion in biomechanics. Method: For this purpose, a linear model that represents the effect of the center of hip joint rotation and the rotation of the marker position on the response was formulated. Five male subjects performed hip joint functional motions, and the positions of nine markers attached on the thigh with respect to the pelvic coordinate system were acquired at the same time. With the nine marker positions, the center of hip joint rotation and marker positions on the thigh were estimated as parameters in the general linear model. Results: After examining the fitted model, this model did not fit the data appropriately. Conclusion: A refined model is required to take into account specific characteristics of longitudinal data and other covariates such as soft tissue artefacts.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2010년도 춘계학술발표대회 초록집
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• pp.53-53
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• 2010

The purpose of this paper is to propose a mathematical model of welding current for the P-GMAW by modifying the well known GMAW model. Welding power circuit is simply modeled as a RL electric circuit and solved as an ODE equation. The welding current depends on the joint shape, molten pool and welding parameters. To compare the molten pool effect to the welding current, CFD numerical simulation technique was adopted. Welding experiment is also conducted with the same welding parameters as used in numerical simulations to verify the proposed welding current model. The current model which is considered molten pool shape, is more fit to experiment result.

• Journal of Welding and Joining
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• 제28권4호
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• pp.55-60
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• 2010

The purpose of this paper is to propose a mathematical model of welding current for the P-GMAW by modifying the well known GMAW model. Welding power circuit is simply modeled as a RL electric circuit and solved as an ODE equation. The welding current depends on the joint shape, molten pool and welding parameters. To compare the molten pool effect to the welding current, CFD numerical simulation technique was adopted. Welding experiment is also conducted with the same welding parameters as used in numerical simulations to verify the proposed welding current model. The current model which is considered molten pool shape, is more fit to experiment result.

• Physical Therapy Rehabilitation Science
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• 제6권3호
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• pp.140-145
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• 2017

Objective: The purpose of this study was to investigate the effect of visual block with ankle joint fatigue on gait and dynamic balance ability. Design: Cross-sectional study. Methods: Thirty healthy young adults (men=15, women=15) between 22 to 25 years of age voluntarily participated in this study. All subjects performed the gait and dynamic balance test successively in two conditions: the visual block and the open eyes condition. Before the gait and dynamic balance test, muscle fatigue on the ankle joint was induced to all subjects by doing ankle dorsiflexion and plantarflexion alternately, and then gait parameters (step length, stride length, cadence, velocity, single limb support, and double limb support) were assessed by walking on the GAITRite system (CIR Systems Inc., USA). Subjects also performed the functional reach test (FRT) for assessment of dynamic balance. This study examined gait parameters and FRT scores in each visual block and open eyes condition. Results: The results showed that FRT scores with the visual block condition significantly decreased compared to without visual blocking (p<0.01). Step length, stride length, cadence, and velocity of gait parameters decreased significantly in the visual block condition (p<0.01) while there was no significant difference for single limb support. However, double limb support increased significantly in the visual block system (p<0.01). Conclusions: Therefore, blocking of visual information with muscle fatigue of the ankle joint can affect gait and balance ability of young adults and increase the risk of falls.