• Journal of Digital Convergence
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• v.13 no.8
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• pp.495-502
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• 2015

The purpose of this study was to investigating the effect of taping knee by testing the difference on kinetic variables of lower extremity when speed skating athletes jump on one leg. The results were as follows. The height of jumping after taping was higher, but the vertical height was not different according to taping. On take-off(TO), the horizontal and anterior-posterior maximum impulse force were decreased while the vertical maximum impact force was increased after taping. On landing(LD), the anterior-posterior maximum impulse force was decreased but the horizontal and vertical maximum impulse force were increased. TO, the impulse showed low after taping and the impulse dropped largely LD. The knee's moment of extension, eversion were reduced after tapping TO. LD, the flection moment of knee was decreased, but the inversion moment was increased after tapping. This study implies that the knee tapping helps injury prevention and performance enhancement, sports medicine convergence are needed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.4
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• pp.61-79
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• 2016

This study aims at examining the structural and managemental problems of the existing fishways which affect the migrations of fishes, and at suggesting alternatives to improve the fishways' efficiency. The study focuses on the fishways constructed in the diversion weirs in the lower reaches of 41 rivers(2 national rivers and 39 rural rivers) in the eastern coast of Korea. Most of water-using facilities in Korean rivers are diversion weirs, and fishways are established as subsidiary facilities of most of the weirs. Among the 58 or so fishways examined in this study, only a few are doing their proper function, and most of them need improvement. This study aims at strengthening those fishways function and increasing their economic efficiency and migration efficiency. Based on the results of this study, the followings are suggested. In case the fishway sticks out downstream from the apron, a subsidiary fishway diverging from the main is suggested to attract fish. The entrance to the subsidiary should head below the raised part of the apron and a pool should be constructed in the connecting part with the main. To attract fish and let the upstream migrators rest for a while, an entrance pool should be constructed in the fishway. Most of the examined fishways have low side walls, which allow the upstreamers to jump out of the fishway. Those side walls are suggested to be raised above the jumping height of target fishes. The exit parts of most fishways are too shallow, or have no grass to protect the fish from the birds. Protective facilities are suggested to keep the birds from entering the fishway. By the time Ice-harbor type and Vertical-slot type fishways are scientifically proved to be defective, the fishway should not diverge from the standard design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1145-1151
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• 2010

In this paper, we discuss the design and simulation of a jumping-robot mechanism that is actuated by SMA (shape memory alloy) wires. We propose a jumping-robot mechanism; the structure of the robot is inspired by the musculoskeletal system of vertebrates, including humans. Each robot leg consists of three parts (a thigh, shank, and foot) and three kinds of muscles (gluteus maximus, rectus femoris, and gastrocnemius). The jumping capability of the robot model was tested by means of computer simulations, and it was found that the robot can jump to about four times its own height. This robot model was also compared with another model with a simpler structure, and the performance of the former, which was based on the biomimetic design, was 3.3 times better than that of the latter in terms of the jumping height. The simulation results also verified that SMA wires can be suitable actuators for small jumping robots.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.967-974
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• 2009

Experiments were conducted to measure the heat flux and temperature over a protuberance, using an impulse hypersonic shock tunnel-coaxial thermocouples and a blowdown hypersonic wind tunnel-temperature sensitive paints(TSP). Experimental data were compared with the heat flux data using a blowdown hypersonic wind tunnel-heat flux gauges and it was confirmed data sets agreed well. The measured heat flux is large when the height of the protuberance is large. Also, the heat flux measurements at the upper positions are larger than at the lower positions. For high protuberances, a severe jump in the heat flux is observed, from about 0.6~0.7 of the height of the protuberances. However, when the protuberance is sufficiently short, a rise in the heat flux is rarely observed as the protuberance is submerged totally under the separation region.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.562-570
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• 2009

An Experimental study was conducted on the flow characteristics and interference heating caused by a two-dimensional object protruding from a flat plate using a blow-down type of hypersonic wind tunnel. Inflow condition was a free-stream Mach number of 7.0 and a unit Reynolds number of $2.0{\times}10^6/m$. Experimental conditions were varied with three heights of protuberance for two flat plate models which have different lengths. Experimental data were obtained from Schlieren visualization images and heat flux measurements. Also, this paper suggests hypersonic experimental techniques such as boundary-layer detection method in detail. A Large separation region was observed in front of the protuberance and that region was very sensitive to the height of protuberance and the length of the flat plate. For only the highest protuberance, a severe jump of heat flux was observed at the top station among the measuring points. Measured heat flux is large when the height of protuberance is large and the length of flat plate is long.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.119-134
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• 2004

The purpose of this study was to analyze the angular momentum characteristics of the Fosbury Flop high jump and the role of the body segments for the production of 3 angular momentum components. The subjects were three male jumpers who were former Korean national team players. Their jumping motions were analyzed using the DLT method of three-dimensional cinematography. The conclusions were as follows. 1. All the forward angular momentum needed to clear the bar was created in the take-off phase. Take-off leg was the great contributor of the forward angular momentum. On the other hand, free leg produced large opposite angular momentum. 2. All subject had some lateral angular momentum before the take-off phase. Head and free leg had major contribution to the lateral angular momentum production. Take-off leg produced opposite angular momentum. 3. All subject had some twisting angular momentum, which make the back of the athlete him to the bar, before the take-off phase. Free leg was the major contributor of the twisting angular momentum. Head and trunk was the second contributor of the twisting angular momentum. 4. Total angular momentum needed to clear the bar had no significant correlation to the jumping height. 5. Subject who made excessive angular momentum showed different pattern of angular momentum production and had a poor record compared to other subject.

• Physical Therapy Korea
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• v.11 no.4
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• pp.1-6
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• 2004

The kinematics involved in different landing strategies may be related to the occurrence of trauma. Several sources suggest that the angle of knee extension on touchdown and impact with the ground determines the magnitude of the impact force and, indirectly, knee loading. This study compared the initial knee angle and maximum knee flexion angle at the instant of impact on drop-landings between healthy men and women. In this study, 60 participants (30 males, 30 females) dropped from a height of 43 cm. A digital camera and video motion analysis software were used to analyze the kinematic data. When landing, there was significant difference between the two groups ($15.67{\pm}6.05^{\circ}$ in male, $24.10{\pm}6.34^{\circ}$ in female) in the mean knee flexion angle. The range of knee flexion on landing ($44.06{\pm}10.97^{\circ}$ in male, $36.96{\pm}9.99^{\circ}$ in female) also differed significantly (p<.05). The greater knee flexion that was observed in the male subjects would be expected to decrease their risk of injury. Women land with smaller range of knee flexion than men and this might increase the likelihood of a knee injury.

• Journal of Sensor Science and Technology
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• v.11 no.6
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• pp.365-370
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• 2002

The jumping ring apparatus described in this study is used to demonstrate and educate the effects of electromagnetic induction. Placing an aluminum ring over the core and switching on AC source causes the ring to jump in the air due to induced currents in the ring producing a magnetic field opposed to that produced in the core. This force is a function of flux density, ac current of ring and levitated height of the ring. Using photo sensor arrays, detect the ring position and represent the position of the ring to analog voltage for an education performance. This paper presents modelling of the jumping ring system and shows how does control signal generate in order to follow desired position.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.1-18
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• 2005

The purpose of this study was to evaluate performance characteristics. in the success of team attack during volleyball competition. For this, real game was analyzed using S-VHS video camera for three dimensional cinematography. The contents of this research were receive to set time, set to spike time, setter moving distance, ball position during set and attacker's relative ball position during jump and spike, and open area at spike. Among the various kinematical factors considered in this study, the ball height relative spiker and open area were found to be related to offensive performance. This finding implies that although their direct impact were not significant the other factors could have indirect impact on offensive performance by increasing open area. Thus, receiver, setter, assistant attacker, and main attacker should practice for successful performance in each stage. Lastly, it is necessary to develop kinematic variables to evaluate performance characteristics of players. Further study may consider the best defense position against the attack of the opponent player.

• Atmosphere
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• v.17 no.3
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• pp.231-240
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• 2007

The flow regimes of continuously stratified flow over a double mountain and the effects of a double mountain on wave breaking, upstream blocking, and severe downslope windstorms are investigated using a mesoscale numerical model (ARPS). According to the occurrence or non-occurrence of wave breaking and upstream blocking, three different flow regimes are identified over a double mountain. Higher critical Froude numbers are required for wave breaking and upstream blocking initiation for a double mountain than for an isolated mountain. This means that the nonlinearity and blocking effect for a double mountain is larger than that for an isolated mountain. As the separation distance between two mountains decreases, the degree of flow nonlinearity increases, while the blocking effect decreases. A rapid increase of the surface horizontal velocity downwind of each mountain near the critical mountain height for wave breaking initiation indicates that severe downslope windstorms are enhanced by wave breaking. For the flow with wave breaking, the numerically calculated surface drag is much larger than theoretically calculated one because the region with the maximum negative perturbation pressure moves from the top to the downwind slope of each mountain as the internal jump propagating downwind occurs.