• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.243-248
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• 2016

Objective: The aim of this study was to determine the kinematical characteristics of somersault with twist in the Lou Yun and Akopian motions and to provide useful information to gymnastic athletes in men's vault. Method: The study subjects were 12 male adult top athletes. After 12 trials (7 Lou Yun and 5 Akopian trials) filmed by using two digital high-speed camcorders set at 90 frames/sec, kinematical data were collected through the direct linear transformation (DLT) method. The mean differences in biomechanical variables were compared during the second flight upward phase. The kinematic characteristics of somersault with twist in the Lou Yun and Akopian motions were identified. Results: In Lou Yun motion, the vertical release velocity through horse breaking was not difficult to obtain, so the athletes had enough time to prepare for the twist. Therefore, the Lou Yun motion has an advantage to make a cat twist in the pike posture. In the Akopian motion, obtaining the horizontal velocity through horse pushing was so easy that the Akopian athletes attained a large angular impulse and angular momentum. Therefore, the Akopian motion has an advantage to making a tilt twist in the body tilting posture. Conclusion: This study suggests that gymnastic athletes should control their body segment movements in order to increase the twisting angular velocity of the whole body, which requires regulation of the longitudinal moment of inertia of the body. Moreover, athletes should prepare for the shoulder and hip twists early in order to make the landing position in advance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.1
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• pp.64-72
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• 2004

In this paper. we analyse and present electro-mechanical dynamic characteristics of a micro-machined vibrating silicon ring gyroscope which can measure angular velocities about three orthogonal axes. The ring gyroscope has a ring connected to the gyroscope main body by support-ligaments which are arranged with cyclic symmetry. The natural modes of its vibration can be distinguished into the in-plane motion and the out-of-plane motion which are coupled by the gyro-effect due to the rotation of the gyroscope main body. The motions of the ring are electro-statically derived. sensed and balanced by electrodes. The equations of motion are formulated. The measuring method of angular velocities by force-to-rebalance is presented. The dynamic characteristics of a ring gyroscope are calculated and compared.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.37-43
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• 2002

In this paper, we analyse and present mechanical dynamic characteristics of a micro-machined vibrating silicon ring gyroscope which can measure angular velocities about three orthogonal axes. The ring gyroscope has a ring connected to the gyroscope main body by support-ligaments which are arranged with cyclic symmetry. The natural modes of its vibration can be distinguished into the in-plane motion and the out-of-plane motion which are coupled by the gyro-effect due to the rotation of the gyroscope main body. The equations of motion, the response to angular velocities, and the relationships between the natural modes of vibration are derived and compared with the previous studies for the design of a micro three-axis ring gyroscope.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.129.2-129
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• 2001

Visual effects are important cues for providing occupant s with virtual reality in a vehicle simulator which imitates real driving. The viewpoint of an occupant is sensitively dependent upon the occupant´s posture, therefore, the total body motion must be considered in a graphic simulator. A real time simulation is required for the dynamic analysis of complex human body motion. This study attempts to apply a neural network to the motion analysis in various driving situations. A full car of medium-sized vehicles was selected and modeled, and then analyzed using ADAMS in such driving conditions as bump-pass and acceleration. A multibody system analysis software, MADYMO, was used in the motion analysis of an adult male dummy in the seated position. Position data of the head were collected as inputs to the viewpoint movement. Based on these data, a back- propagation neural network was ...

• The KIPS Transactions:PartA
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• v.8A no.2
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• pp.167-178
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• 2001

This paper presents a new methodology for specification and control of the motion of an articulated rigid body for the purposes of animation by coordinate transformations. The approach is to formulate the problem as a coordinate transformation from the joint space of the body to a user-defined animation space which is chosen for convenience in constraining the motion. Constraints are applied to the resulting coordinate transformation equations. It is sufficiently general so that it can be applied to all common types of control problems, including closed loop as well as open loop mechanisms. We also provided a new approach to simulate a closed loop mechanism, which is using animation space transformation technique. The method is formulated in detail and is demonstrated by animating the motion of an inchworm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.970-976
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• 2003

In this paper, we analyse and present electro-mechanical dynamic characteristics of a micro-machined vibrating silicon ring gyroscope which can measure angular velocities about three orthogonal axes. The ring gyroscope has a ring connected to the gyroscope main body by support-ligaments which are arranged with cyclic symmetry. The natural modes of its vibration can be distinguished into the in-plane motion and the out-of-plane motion which are coupled by the gyro-effect due to the notation of the gyroscope main body. The motions of the ring are electro-statically derived, sensed and balanced by electrodes. The equations of motion are formulated. The scheme of angular velocities sensing by force-to-rebalance method is presented. The dynamic characteristics of a ring gyroscope are calculated and compared.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.99-108
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• 2005

This paper represents an efficient modeling method of a suspension system for the vehicle dynamic simulation. The suspension links are modeled as composite joints. The motion of wheel is defined as relative one degree of freedom motion with respect to car body. The unique relative kinematic constraint formulation between the car body and wheel enables to derive equations of motion in terms of wheel vertical motion. Thus, vehicle model has ten degrees of freedom. By using velocity transformation method, the equations of motion of the vehicle is systematically derived without kinematic constraints. Various vehicle simulation such as J-turn, slowly increasing steer, sinusoidal sweep steer and bump run has been performed to verify the validity of the suggested vehicle model.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.193-201
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• 2002

The development of railway vehicle and bogie involves the proper selection of design parameters not only to achieve high speed but also to reduce the vibration of the train. In this study an analytical model of a high speed freight car is developed to find the critical speed. The high speed freight car can generate the snake motion of the lateral and yawing motion of the car body, the bogie, and the wheelset. Numerical analysis for the nonlinear equation motions with 17 degrees of freedom showed the running stability and critical speed due to the snake motion. Also, the vibration modes of tile high speed freight car was calculated using ADAMS RAIL, which showed that the critical speed have the yawing modes of the car body and the bogie. Finally, this paper shows that the snake motion of the vehicle can be controlled with the modifications of the design parameters.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.12
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• pp.1001-1009
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• 2002

In this paper, we analyse and present mechanical dynamic characteristics of a micro-machined vibrating silicon ring gyroscope which can measure angular velocities about three orthogonal axes. The ring gyroscope has a ring connected to the gyroscope main body by support-ligaments which are arranged with cyclic symmetry. The natural modes of its vibration can be distinguished into the in-plane motion and the out-of-plane motion which are coupled by the gyro-effect due to the rotation of the gyroscope main body. The equations of motion, the response to angular velocities, and the relationships between the natural modes of vibration are derived and compared with the previous studies for the design of a micro three-axis ring gyroscope.

• Korean Journal of Applied Biomechanics
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• v.31 no.4
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• pp.283-289
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• 2021

Objective: The aim of this study was to analyze the pattern of Kolman technique by five Korean top gymnasts including the three national athletes on horizontal bar. Method: Two digital high-speed camcorders were used with 90 frames/sec and their Kolman motions were filmed in sports science secondary school gymnasium at U city. After the kinematic and kinetic variables were carried out by Kwon3D 3.1 motion package during the whole phase, the optimized release motion was investigated by simulating the body COG path during the aerial phase. Results: Firstly, it was revealed that the average changes of hip, shoulder joint angle were 84 deg, 53 deg respectively during the functional sub-phase and the average swing phaseal time was 1.21 s. Secondly, it was revealed that the average body COG positions and velocities (Y, Z) at release were -0.65 m, 0.48 m, 1.65 m/s, 3.97 m/s respectively and the average release angle, peak height and flight time were 67 deg, 1.29 m, 0.79 s respectively. Thirdly, it was revealed that the directions of somersault of whole and lower body, tilt of lower body were counterclockwise, whereas the directions of tilt of whole body, twist of whole and lower body were clockwise at the ready for re-grasp. Lastly, it was revealed that the body COG paths were different from each other during the aerial phase followed by the different body COG velocities. Conclusion: Korean gymnasts of this study controlled their motions well in terms of the timing of hip·shoulder joint, body position, body angular momentum especially during the functional sub-phase, but their motions were different during the aerial phase. Nonetheless most of them made the adequate body position at the instant of re-grasp. It would be suggested that Korean gymnasts except S3 should increase the vertical velocity.