• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.621-626
• /
• 2002

Two problems in the measurement of 6-DOF head vibration in very low frequency range were investigated in this study. One is how much error was involved in the estimation of three rotational and three translational motion at any specified point from measured 6 translational accelerations. The other is quantitative and qualitative influence of gravity on DC and AC component of the estimated accelerations in 6 degree of freedom, which were derived from pick-ups fixed on a helmet. In the study the effect of nonlinear terms on the estimation of 6 degree of freedom accelerations was negligible but gravity effect must be considered carefully.

• PNF and Movement
• /
• v.7 no.1
• /
• pp.25-32
• /
• 2009

Objective : The purpose of this study was conducted to find the change of shoulder flexion by degree of freedom between the Proprioceptive Neuromuscular Facilitation(PNF) pattern, the flexion- abduction- external rotation, and not PNF pattern, the flexion- exteral rotation(except abduction)movement. Method : PNF pattern applied on the unilateral upper extremity in all subjects were the flexion- abduction- external rotation, and not PNF pattern, and twenty-six normal subjects(13 male, 13 female) were tested by Cybex Norm Testing & Rehabilitation System. Results : PNF pattern showed significant increase of flexion than not PNF pattern, the flexion-exteral rotation(except abduction)movement, and also the female group was significantly increased than male group. Conclusion : The results suggested that the application of PNF pattern to the unilateral upper extremity had affected on the shoulder flexion by degree of freedom.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.10
• /
• pp.2501-2513
• /
• 1994

In this paper, a compact, light-weight, universal, spherical 3-degree-of-freedom, parallel-structured manual controller with high reflecting-force capability is implemented. First, the position analysis, kinematic modeling and analysis, force reflecting transformation, and applied force control schemes for a parallel structured 3 degree-of-freedom spherical system have been described. Then, a brief description of the system integration, its actual implementation hardware, and its preliminary analysis results are presented. The implemented parallel 3 degree-of-freedom spherical module is equipped with high gear-ratio reducers, and the friction due to the reducers is minimized by employing a force control algorithm, which results in a "power steering" effect for enhanced smoothness and transparency (for compactness and reduced weight).d weight).

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.1093-1094
• /
• 2010

• Journal of the Ergonomics Society of Korea
• /
• v.15 no.2
• /
• pp.15-24
• /
• 1996

To generate workspace analytically using the robot kinematics, data on range of human joints motion, especially range of two degrees of freedom motion, are needed. However, these data have not been investigated up to now. Therefore, in this research, we are to investigate an interaction effect of motions with two degrees of freedom occurred simultaneously at the shoulder, virtual hip(L5/S1) and hip joints, respectively, for 47 young male students. When motion with two degrees of freedom occurred at a joint such as shoulder, virtual hip and hip joints, it was found from the results of ANOVA that the action of a degree of freedom motion may either decrease or increase the effective functioning of the other degree of freedom motion. In other words, the shoulder flexion was decreased as the shoulder was adducted or abducted to $60^{\circ}C$TEX>or abducted from $60^{\circ}C$TEX>to maximum degree of abduction, while the shoulder flexion increased as the joint was abducted from $60^{\circ}C$TEX> to $60^{\circ}C$TEX> The flexion was decreased as the virtual hip was bent laterally at the virtual hip joint, and also did as the hip was adducted or abducted from the neutral position. It is expected that workspace can be generated more precisely based the data on the range of two degrees of joint motion measured in this study.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.1428-1431
• /
• 1996

This paper proposes an anti-swing control law for a 2 degrees of freedom overhead crane. The dynamic model of a 2 degrees of freedom crane is highly nonlinear and coupled. The model is linearized and decoupled for each degree of freedom of the crane for small motions of the load about the vertical. Then a decoupled anti-swing control law is designed for each degree of freedom of the crane based on the linearized model. The control law consists of a position control loop and an swing angle control loop. The position loop,. is designed based on the loop shaping method and the swing angle loop is designed via the root locus method. Finally, the proposed anti-swing control law is implemented and evaluated on a 2 degrees of freedom prototype crane.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.377-378
• /
• 2002

In many dynamic systems, unwanted vibrations which may arise during operation of machines are costly in terms of reduction of performance and service life. Sometimes these risky oscillations endanger equipment and personnel. When hydraulic telescopic booms taken large mass are driven at slow speeds between the two pads, unstable oscillations occur through the stick-slip at the sliding parts and become more severe and saw-toothed. This paper supposes few models for the telescopic boom in the multi-degree of freedom system, and attempts a theoretical approach for the numerical analysis in its stick-slip condition, It was verified that this theoretical approach has an effect on estimate of stick-slip in the one-degree as well as multi-degree of freedom system.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.258-263
• /
• 1991

Optimal configurations for redundant TDOF (Two Degree Of Freedom) sensor systems are proposed. The determinant of error covariance matrix is used as the performance index, and optimal configurations for 2 TDOF sensor system and 3 TDOF sensor system are evaluated by minimizing the index.

• Journal of Korean Association for Spatial Structures
• /
• v.4 no.4 s.14
• /
• pp.85-89
• /
• 2004

A frame element embedded normal to a shear wall or slab (shell element) is common in the structural systems. In that case there is a need for a membrane or shell element to have a normal rotation degree of freedom at each node in order to have a good result of stresses. Even if Many other people studied this area, All man, Cook and Sabir are representative investigators in this area. In this research paper, Sabir's methods of vertex rotation stiffness matrix in a membrane element are studied. New stiffness of vertex rotation are proposed by taking advantage of beam stiffness theory. Rectangular elements stiffness with rotational degree of freedom are compared in accuracy ratio each other.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.1 s.31
• /
• pp.23-28
• /
• 1999

For offshore structures, dynamic analysis becomes increasingly important as water depth increases and structural configuration becomes more slender. In the case of dynamic analysis of frame structures, much computer time and high cost are required due to many degrees of freedom, In this paper, a new technique of permutating a segment of frame structure to a beam is developed, which is called here Beam Permutation Technique. The technique is based on definition of stiffness matrix of the beam which is obtained by defining the actions(or forces) required to obtain unit translation or rotation for each degree of freedom wiht al other degree of freedom restrained to zero displacement or rotation. In the technique, an assumption is made that relative positions of nodes in the ends of the segment are not variable, The technique can significantly reduce the degrees of freedom of frame structures and thus the computiong time in dynamic analysis. The natural frequencies and static displacements of the permutated beam are obtained and compared to those of ANSYS with a good agreement.