• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.39-47
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• 2015

Objective : The purpose of this study was to investigate the velocity conversion coefficient and invariance for the optimal phase ratio on the performance of the women's triple jump. Methods : Three-dimensional kinematic data were obtained from the three finalists of the women's triple jumper competition at the 2011 Daegu IAAF World Championships. Computer simulations were performed using the biomechanical model of the triple jump to optimize the phase ratio for the longest actual distance for all athletes with altered velocity conversion coefficients. Results : Top elite triple jumpers showed better technical consistency at the phase ratio. Also, no consistent relationship was observed between the loss in horizontal velocity and the gain in vertical velocity across supporting the three phase. In addition, regardless of the magnitude A1, all athletes were optimized with jump-dominated technique. Finally, as the magnitude of A1 increased, the athletes showed better performance. The obtained overall distance jumped showed the longest actual distance when the optimal phase ratio was transferred from hop-dominated to jump-dominated(the step ratio was 30%~31%), and when the optimal phase ratio was transferred from balanced to jump-dominated(the step ratio was 27%~29%). Conclusion : Future studies need to be conducted in order to explore the active landing motion and the inclination angle of the body with the velocity conversion coefficient simultaneously at each supporting phase.

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.27-46
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• 2003

The purposes of this study were to determine the functions of actions of the limbs during each of the three support phases of the triple jump and their relationships with the performance of the triple jump. Four elite male triple jumpers were participated as subjects. The statistical analyses used were the Pearson product moment correlation coefficient for establishing relationships and simple regression analyses to determine and compare the relationships between the change of the horizontal velocity and the change of the vertical velocity during different support phases. A level of significance at p<.05 was set. The actions of the arms were responsible for about 25%, 25%, and 30% of the decrease in the horizontal velocity of the whole body center of gravity during the support phases of the hop, step, and jump, respectively. The change in the velocities of the whole body center of gravity due to the actions of the free limbs were significantly related with the whole body center of gravity during each support phase. The action of the support leg was associated with the decrease in the horizontal velocity and the increase in the vertical velocity of the whole body center of gravity during each support phase.

• Korean Journal of Applied Biomechanics
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• v.14 no.1
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• pp.65-81
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• 2004

The purposes of this study were to determine the functions of actions of the limbs during each of the three support phases of the triple jump and their relationships with the performance of the triple jump. Four elite male triple jumpers were participated as subjects. The Pearson product moment correlation coefficient were used to determine and compare the relationships between the change in each component of the normalized angular momentum of the whole body about center of gravity and the actions of the extremities during different support phases. A level of significance at $\alpha$=.05 was set. After analyzing the angular momentum and correlation during support phase of the hop, step, and jump, the following findings are obtained: The actions of the arms created a side-somersaulting angular momentum about the whole body center of gravity toward the side of the free leg during the support phase of the step, and a somersaulting angular momentum about the whole body center of gravity during each support phase. The action of the free leg created a somersaulting angular momentum about the whole body center of gravity during the support phases of the hop and step.

• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.611-619
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• 2011

The purpose of this study was to analyze the kinematics of the men's triple jump at the 2011 Daegu World Championships by comparing the results to those at the 2009 Berlin World Championships. The kinematic data were gathered from two steps before take off to the landing using a seven panorama system, and these data were divided into 3 phases for 8 participants. The average jump for the finalists was longer in the Daegu championships (17.46 m) than in the Berlin championships (17.28 m). The longest jump record was increased by 23 cm. The step was the longest at 36% of the total distance, followed by the hop at 30% and the jump at 34%. The first and third phases were substantially longer than the second phase (the step). The horizontal speed at take-off increased in the order hop, step, and jump. Overall, in comparison with the results from Berlin, the horizontal velocity increased, the vertical velocity decreased, and the landing angle decreased.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.209-216
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• 2008

The purposes of this study were to describe the techniques used by the university male's triple jumpers and to examine the characteristics of the kinematic and the kinetic factors of the three phases of a triple jump. The subjects were the five finalists with 16.70m over in the triple jump at the 2003 World Student Games. After analyzing the kinematic and the kinetic data during the whole triple jump, the following findings are obtained. The heights of the center of gravity of takeoff and touchdown for the three phases of the triple jump were medium-law-high pattern and the same height pattern as hop and step, respectively. Mean values for the average forces exerted on the subjects ranged from 0.6 to 0.7 times body weight to the horizontal direction and about 2.8 to 3.0 times body weight to the vertical direction.

• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.621-629
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• 2011

The purpose of this study was to analyze the kinematics of the women's triple jump event at the 2011 Daegu World a Chmpionships by comparing them to those of the 2009 Berlin World Championships. The kinematic data were gathered from two steps before take off to the landing using a 7-camera panorama system. The data were then divided into 3 phases for each of the 8 participants. Similar average results were found the final contestants in the Daegu and Berlin championships, 14.58 m and 14.51 m, respectively. The first step had a relatively short length percentage (29%) compared to the hop and jump (36% and 35%, respectively). At the take off, the horizontal velocity was the lowest for the step, followed by the hop and jump. These results were different from the results for the men, who had an order of hop, step, and jump. Overall, in a comparison of the Daegu and Berlin participants, the vertical speed at take off for the three events was reduced compared to the horizontal speed.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.253-259
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• 2010

The aim of IAAF's Biomechanics project, initially launched at the 1987 World Championships in Rome, is to support athletes and coaches in the optimization and improvement of their training and competition performance. The IAF and the IAAF supports biomechanical projects, as a service to their Member Federations, starting from the IAAF World Championships in Rome 1987. In 1997, at the IAAF World Championships of Athens. In 1995, at the IAAF World Championships in Goteborg and in co-operation with the Swedish Sport Institute of Karlstad and under the leadership of Anders Bergstrom a biomechanical research on "Throws" was conducted. In 2005, at the IAAF World Championships in Helsinki on 100m - Pole vault, High Jump, Triple Jump, Javelin, under the leadership of Prof. Paavo Komi. The IAAF published the final report in 2008 with a supplement of NSA. In 2007, at the IAAF World Championships of Osaka, in co-operation with Osaka University of Health and Sport Sciences and under the leadership of Prof. Michiyoshi Ae the IAAF received a final report on; short sprint, distance running, high jump, long jump, shot put and javelin. In 2009, at the IAAF World Championships of Berlin, in co-operation with the DLV and the leadership of Helmar Hommel (GER). The purpose of this study is to draw up a plan to perform an effective biomechanics project at 2011 IAAF World championship in Daegu.

• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.503-510
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• 2011

The purpose of this study was to find the biomechanical research project result carried out at 2011 IAAF World championship in Daegu. This project was approved by the International Amateur Athletic Federation(IAAF) and financially supported by the Ministry of Culture, Sports and Tourism(MCST) and, Korea Association of Athletics Federations(KAAF). The total number of the project members was 20, including the members of the Scientific Committee, the Korean Society of Sport Biomechanics(KSSB) and graduate students as assistants. The objective of this project has been to analyze the performance in the track events(100 m, 110 mH) and field events(Long Jump, High Jump, Triple Jump, Pole Vault, Javelin Throw and Shot Put). This project was focused on the biomechanical research only. This kind of analysis has been carried out at major competitions for more than a decade, as it provides coaches and athletes with very useful information as an aid to training programmes and competition preparation. The biomechanical analysis of the top athletes in the world in each specialty serves as a reference for assessing technique and rationalizing the results achieved. The results will be disseminated world-wide and coaches will be in a better position to design training strategies in line with current world trends.

• Journal of Advanced Technology Convergence
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• v.1 no.1
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• pp.33-42
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• 2022

The flexors and extensors of the knee joint are essential for maintaining body stability. The purpose of this study was to investigate the correlation between the isokinetic parameters of the knee flexor and extensor muscles and the function of the lower extremity muscles. Twenty-two healthy adults participated in this study. The time to peak torque (TTP), acceleration time (AT), and peak torque (PT) of the knee flexor and extensor muscles were measured. A 20m sprint, Sargent jump, one leg hop test, and side shuffle were measured to evaluate lower extremity function. The correlation between each variable was analyzed using Pearson correlation coefficient. PT of the knee flexor showed a significant correlation with single leg hops and 6M hops in a single leg. PT of knee extensors was found to be significantly correlated with Sargent jumps and triple hops. Based on the results of this study, we suggest that the strength of the knee flexor and extensor muscles has the potential to be used to predict lower extremity function.

• Nuclear Engineering and Technology
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• v.42 no.6
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• pp.620-635
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• 2010

In this paper we describe current activities on the project Multi-Scale Modeling and Analysis of convective boiling (MSMA), conducted jointly by the Paul Scherrer Institute (PSI) and the Swiss Nuclear Utilities (Swissnuclear). The long-term aim of the MSMA project is to formulate improved closure laws for Computational Fluid Dynamics (CFD) simulations for prediction of convective boiling and eventually of the Critical Heat Flux (CHF). As boiling is controlled by the competition of numerous phenomena at various length and time scales, a multi-scale approach is employed to tackle the problem at different scales. In the MSMA project, the scales on which we focus range from the CFD scale (macro-scale), bubble size scale (meso-scale), liquid micro-layer and triple interline scale (micro-scale), and molecular scale (nano-scale). The current focus of the project is on micro- and meso-scales modeling. The numerical framework comprises a highly efficient, parallel DNS solver, the PSI-BOIL code. The code has incorporated an Immersed Boundary Method (IBM) to tackle complex geometries. For simulation of meso-scales (bubbles), we use the Constrained Interpolation Profile method: Conservative Semi-Lagrangian $2^{nd}$ order (CIP-CSL2). The phase change is described either by applying conventional jump conditions at the interface, or by using the Phase Field (PF) approach. In this work, we present selected results for flows in complex geometry using the IBM, selected bubbly flow simulations using the CIP-CSL2 method and results for phase change using the PF approach. In the subsequent stage of the project, the importance of effects of nano-scale processes on the global boiling heat transfer will be evaluated. To validate the models, more experimental information will be needed in the future, so it is expected that the MSMA project will become the seed for a long-term, combined theoretical and experimental program.