The research was a case study conducted in order to develop a new technique “YANG Hak Seon 2” for YHS athlete. A comparative kinematical three dimensional video analysis was performed with the use of high speed cameras. One successful trial and three of failure trials (T1: Falling backward while landing, T2: sitting reluctantly while landing, T3: Falling of sideways while landing). The result obtained from the study are as follows. Firstly when comparing the successful operation of the technique with failure trials, relatively higher landing angle was secured through increasing the thigh rotation and the body’s rotational velocity. Furthermore, despite increase in rotational velocity at twisting, stable landing was achieved through increasing the moment of inertia by spreading the left shoulder. Secondly, in case of failure trials while taking off the board, the thigh rotational angular velocity was comparatively less which ultimately affected the body position in the next phase of approach to the vault. Thus, due to the affected body position the athlete was not able to utilize the proper momentum of twist in positive direction Hence, it is considered that the velocity of center of mass might have also effected the operation not only the velocity while approaching the board.
