• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.89-99
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• 2006

The study were to assess technical factors between the high score group and the low score group, from the subjects of 16 male national gymnasts, and to analyze the kinematical characteristic and main technical cause on technique of Akopian's 3D motion analysis of the male vaulting game in 2001 classification championship. The result of this study is this. There were not so much difference between the two groups in term; of the time of board contact, pre-flight, and total performance, but it takes shorter time when the players who are in the high point group take down the board, and they take long time for post-flight(p<.01). The high point group has a longer perpendicular distance in the moment of horse taking off, 0.05m on the average, than the low point group. The high point group shows 0.16m higher on the average than the other group in term; of the height of post-flight(p<.01). In the phase of board contact, the range of horizontal velocity at board take on were $7.66m/s{\sim}7.33m/s$, but there weren't significantly statistic differences between two groups. The hight score group were 0.68m/s faster than the low point group at the horizontal velocity at board take off event(<.05). About the average horizontal velocity of deceleration, AG1(-1.95m/s) reduces the speed more than AG2(-1.57m/s)(p<.05). And the hight score group were 0.37m/s faster than the low point group at the vertical velocity at horse take off event(<.05). When board taking off, the projectile angle of com were $38.7{\sim}37.8degree$ on the average. the comparative groups show almost same results. When horse taking off, the HPVy of the high point group were 37.6 degree which were a little higher than the low point group. The angular velocities of the players who takes on the horse with a right hand and then takes off with a left hand in the high point group were 14.97rad/sec, 10.82rad/sec in the low point group. However, the angular velocity of the players who takes on the horse with a left hand and then takes off on a right hand with the high point group were 14.97rad/sec, 15.56rad/sec in the low point group.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.11 no.1
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• pp.57-66
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• 2003

This study is performed to secure the safety of civil aviation by establishing systematic analysis ability of Flight Data Recorder. Through this study, we analysed the flight data of A321 & A330 aircraft with lift angles and take-off actions of flight crew members.

• The Journal of Information Systems
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• v.14 no.1
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• pp.251-275
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• 2005

The advantages of implementing a virtual channel can be derived from the notion of the 'death of distance' that would result from electronic commerce. According to this view, the internet was going to make distance irrelevant, in that firms would no longer need to establish a physical presence in a geographical location in order to do business there. However, on-line firms selling physical products could take advantages of presence in the related off-line(brick and mortar) industrial area. This paper developed a conceptual framework that highlights the various types of synergies by location on-line businesses in the related off-line industrial area. Using data from 96 on-line ventures selling physical products, factor analysis was used to figuring out six synergies including improved customer trust, value-added service, cost savings, personnel and organizational efficiency, sharing products and customer information, relationship with suppliers, and relationship with local government. The six empirically derived critical synergy factors were then used to examine how they improve performance of the on-line ventures measured by Balanced Scorecard(BSC). According to lthe results, we concluded that the on-line firms selling physical products can take advantages of presence in the related off-line industrial area.

• Journal of Aerospace System Engineering
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• v.8 no.4
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• pp.1-6
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• 2014

This paper presents the trade-off study of conducting a survey of the weights for various kind of propulsion systems installed in the Smart Unmanned Aerial Vehicle TR-100, a tilt-rotor vehicle, which is developed by Korea Aerospace Research Institute, in order to predict the appropriate propulsion system for present and future Personal Air Vehicle, which has single mode and vertical take-off & landing. In order to perform the trade-off study, we set the requirements that the vehicle hovers for 1 hour with 1,000 kg maximum take off weights. In this study, the power systems are classified engine, which uses the fossil fuel - turboshaft engine, piston engine, diesel engine and rotary engine, and electric motor with fuelcell or Li-Ion battery. The results of trade-off study shows the power systems using fossil fuel are superior to using fuelcell or Li-Ion battery for weight of propulsion system. Also turboshaft engine is the best power system for the aspects of system weight, and the nexts are rotary engine, piston engine, diesel engine, electric motor with Li-Ion battery, and electric motor with fuelcell.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.1-10
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• 2015

Objective : The purpose of this study was to find some kinetic variable's relationships between personal records and low records in female high jump. Methods : Collected data of the subjects(N=8, ages: $25.5{\pm}1.85$, height: $173{\pm}5.83$, mass: $54.75{\pm}6.36$ personal record: $1.71{\pm}0.04$, low record: $1.62{\pm}0.03$) were used for the last three strides and take-off phase. Five video cameras set in 30frames/s were used for recording. After digitizing motion, the Direct Linear Transformation(DLT) technique was employed to obtain 3-D position coordinates. The kinematic and kinetic factors of distance, velocity, angle, impulse, jerk variables were calculated. A paired t-test was applied for the difference of variables between personal records and lower records and for correlation with performances and variables. The significance level was accepted at p<.05. Results : There was no relationship between pattern of stride and performance. However, rate of change of velocity was related with cental of mass height(CMH) at peak point(PP). Knee, hip, backward lean, foot plant, approach and take off angle showed no difference between best record and low record. Vertical impulse momentum also showed no difference between performances. Conclusion : According to a t-test result, there were significant differences in CMH at PP and jerk at touch down between best record and low record.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.157-166
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• 2007

This study was to compare the major kinematic factors between the success and failure group on performing the back somersault motion in floor exercise. Three gymnasts(height : $167.3{\pm}2.88cm$, age : $22.0{\pm}1.0years$, body weight : $64.4{\pm}2.3kg$) were participated in this study. The kinematic data was recorded at 60Hz with four digital video camera. Two successful motions and failure motions for each subject were selected for three dimensional analysis. 1. Success Trail It was appear that success trail was larger than failure group in projection velocity, but success trail was smaller than failure trail in projection angle. Also it was appear that success trail was longer than failure group in the time required. Hand segment velocity and maximum velocity in success trail were larger than those in failure trail, and this result was increasing the projection velocity and finally increasing the vertical height of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle was contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle was maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of success trail extended more than those of failure trail. in this base, success trail in upward phase(p3) 2. Failure Trail It was appear that failure trail was smaller than success trail in projection velocity, but failure trail was larger than success trail in projection angle. Also it was appear that failure trail was more short than success trail in the time required. Hand segment velocity and maximum velocity in failure trail were smaller than those in success trail, and this result was reducing the projection velocity and finally reducing the vertical high of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle wasn't contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle wasn't maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of failure trail didn't extended more than those of success trail.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.53-62
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• 2008

The purpose of this research was to analyze the kinematics of the 205B movement in platform diving. For the experiment, 2 athlete from the national diving team were chosen as the subject and two S -VHS video cameras were used. For this diving players preparing for the olympics participated. It was shown that the mean total took $1.112{\pm}0.12s$. In order to perform better, the divers time must be increased, at take off and rotation must be done high up and the horizontal distance must be shorted to main entrance of the water. To enter the water safely, the jump has to be high, the horizontal speed slow and the vertical speed as fast as possible. At E1 the lower limbs change in speed should decrease and after the rotation begins at E2. At take off, the jump is more important than the rotation for the performance of the dive. At take off, the trunk angular velocity was high, and this was needed to jump high for moment of inertia for rotation because for efficient jumping the upper body has to spread out and increase the height of the center of mass.

• Korean Journal of Applied Biomechanics
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• v.15 no.2
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• pp.129-138
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• 2005

The purpose of this study was to investigate the techniques used by long jumpers who recorded over 8meters in 2002 Busan Asian Game and 2003 Daegu Universiade. The kinematic characteristics from the last three stride to takeoff at the takeoff board were analyzed such as velocities, heights and angles. The real-life three-dimensional coordinates of 20 body landmarks during each trial were collected using a Direct Linear Transformation procedure. The conclusion were as follows; 1. The height variation who recorded over 8 meters of center of gravity of the jumpers at the last stride was under 8cm. In order to record over 8meters the national long jumpers should have under 10cm height variation. 2. In the approach phase the horizontal velocity of the jumpers should reach to 10.5m/s in last three strides and 9.79m/s in touch down at take off board. 3. The horizontal velocity at take off board must have over 8.51m/s and the vertical velocity must have 3.75m/s simultaneously in order to record 8meters. 4. The forward body lean angle should have over 20degrees with pushing the take off board in forwarding movement. The appropriate body variation range ratio between take off and touch down should be 1.2 vs 1 and the trunk angle at touch down on the board should be close to the erect posture for higher body flight.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.603-610
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• 2017

Various type of pavement deterioration such as crack, bumpy, pothole is rapidly increasing according to the accelerated environmental changes like heavy rainfall, frequent snowing, difference temperature, etc. Accident related to pothole that cause fatal traffic accidents has been increased more than five times over the next five years starting from 2008. As direct or indirect damage by pothole which caused injuries and car damages increases every year, quicker and more efficient management measures are necessary. This study presents the algorithm for materials quantity take-off. The algorithm was suggested by correlation in pothole size and area. Suggested algorithm were confirmed the validity through the 15 field survey in capital area. According to the results of survey, usually the residual materials at which 5~7 kg was generated decreased to 1~2 kg. It showed that automatic pothole detection system is expected not only to reduce materials and resources, but also to contribute to quality improvements of pavement through more accurate material take-off from the situation of constructing rely on their own judgement.

• Korean journal of applied entomology
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• v.40 no.2
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• pp.125-129
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• 2001

Some wingless species have evolved take-off behaviors that enable them to become airborne. We examined aerodynamic attributes of dispersal relative to the body size and standing vs. walking postures for three phytoseiids that were suspected to have different take-off behaviors and dispersal abilities, Phytoseiulus persimilis Athias-Henriot, Neoseiulus fallacis (Carman) and N. californicus (McGregor). The average vertical profile of Pp in the walking position was significantly higher than those of Nf and Nc when in walking position. The body height of Nf in the standing posture was significantly greater than the body height of Pp when in the walking position. Cross-section areas also showed similar patterns of difference. Nf in the standing posture would have more than twice the drag force than in walking posture because of more fluid momentum in the wind boundary layer However, Pp in the walking position would have similar drag to Nf in the standing posture because of a higher vertical profile and larger size. Thus we add the scientific evidence of presence and absence of take-off behavior of some phytoseiid mites and evolutionary aspects of aerial dispersal are further discussed.