• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.133-145
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• 2007

The purpose of this paper was to compare of difference between energy walking and normal walking. Subjects were selected 8 male undergraduates. The kinematic variables of a pelvis and a thorax were analysed at the take off and contact with 3d cinematography. In addition to the variables, the phase plot angle was calculated in order to definite characteristics in the phase space. The pelvic angle and angular velocity showed significant differences in the flexion/extension between two walking patterns. The pelvic angle and angular velocity were increasing when walking speed was increasing and magnitude of the variables of energy walking was larger than corresponding values for normal walking. On the other hand, the thoracic angle demonstrated significant differences in the flexion/extension and rotation between two walking patterns. The angles of energy walking were smaller in the flexion/extension and were larger in the rotation than the angle of normal walking. The kinematic characteristics of energy walking were also showed clearly significant differences in the range of motion and the relative angle of the trunk. The angle of phase plot only showed demonstrated a significant difference in the rotation at contact between the two walking patterns.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.179-189
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• 2012

The aim of this paper is to research the change in the turbulent flow and the AOA(Angle Of Attack) occurred by $40^{\circ}$ crosswind to the direction of runway through the three-dimensional numerical analysis and to predict the take-off and landing flight stability. As a result, the maximum amplitude of AOA variation on runway reached $2^{\circ}$ within 3 second because of the wake formed by the constructions in the vicinity of the airport, and the overall effects appeared as an irregular aperiodic forms. Additionally, it was observed that the layout and shape of the buildings effected on the strength of turbulence directly, and the rapid flow generated between the buildings changed into stronger wake and eventually expected that the flow raises serious take-off and landing flight instability.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.114-122
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• 2022

This paper explores three-dimensional unsteady computational fluid dynamic (CFD) analyses with an overset grid technique to analyse the wake effect created by a rotating propeller on a hand-launched unmanned aerial vehicle (UAV). Additionally, the influence of actual aileron deflection on the equilibrium condition of the rolling moment is examined in various hand-launched take-off conditions. The results of this study demonstrate the importance of initial aileron deflection in increasing the initial rolling stability during the hand-launched take-off process. Furthermore, an aerodynamic database is constructed to rapidly predict the aileron set values required for different take-off speeds and angle-of-attacks.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.333-336
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• 2003

For long time, the takeoff and landing control of airship was worked by human handling. With the development of the autonomous control system, the exact controls during the takeoff and landing were required and lots of methods and algorithms were suggested. This paper presents the result of airship take-off and landing by buoyancy control using air ballonet volume change and performance control of pitch angle for stable flight within the desired altitude. For the complexity of airship's dynamics, firstly, simple PID controller was applied. Due to the various atmospheric conditions, this controller didn’t give satisfactory results. Therefore, new control method was designed to reduce rapidly the error between designed trajectory and actual trajectory by learning algorithm using an artificial neural network. Generally, ANN has various weaknesses such as large training time, selection of neuron and hidden layer numbers required to deal with complex problem. To overcome these drawbacks, in this paper, the RBFN (radial basis function network) controller developed.

• Nuclear Engineering and Technology
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• v.36 no.2
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• pp.142-152
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• 2004

The liquid entrainment and vapor pull-through offtake model of RELAP5/MOD3 had been developed for SBLOCA (Small Break Loss of Coolant Accident). The RELAP5/MOD3 model for horizontal volumes accounts for the phase separation phenomena and computes the flux of mass and energy through a branch when stratified conditions occur in the horizontal pipe. In the case of CANDU reactor, this model should be used in the coolant flow of 95 feeders connected to the reactor header component under the horizontal stratification in header. The current RELAP5 model can treat the only 3 directions junctions; vertical upward, downward, and side oriented junctions, and thus improvements for the liquid entrainment and vapor pull-through model were needed for considering the exact angles. The RELAP5 off-take model was modified and generalized by considering the geometric effect of branching angles. Based on the previous experimental results, the critical height correlation was reconstructed by use of the branch line connection angle and validation analyses were also performed using SET. The new model can be applied to vertical upward, downward and angled branch, and the accuracy of the new correlations is more improved than that of RELAP5.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.1
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• pp.11-17
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• 2023

In this study, the correlation analysis between total system error and environmental factor variables was performed to confirm the effect on the performance of the integrated navigation system by various environmental factors. To collect flight data of hybrid vertical take-off and landing UAVs, scenarios including various turning sections and straight sections such as left turn, right turn, turning rate, and path change angle were selected, and environmental data of wind direction, wind speed, temperature, air pressure, and humidity were collected in real time through weather station. As a result of the correlation analysis between the collected flight data and environmental data, it was concluded that the performance of the integrated navigation system by environmental factors within the collected data was not significant affected and was robust.

• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.541-550
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• 2011

The purpose of this study was to investigate the kinematic characteristics of the $5^{th}$ and $6^{th}$ hurdle clearances during the final of the 100-m hurdles event at the IAAF World Championships, Daegu 2011. To this end, the hurdling motions of the top 4 ranked female hurdlers in the competition were analyzed. A total of 12 cameras were used to record their motions, with a sampling frequency of 120 Hz. The cameras were calibrated using $11{\times}2{\times}1\;m$ control objects that covered all of the lanes ($1^{st}{\sim}8^{th}$ lanes). After analyzing all the data, we arrived at the following results. For the take-off phase, a negative relationship between the take-off time (CT) and athlete's rank was found. In addition, the average distances from the hurdle to take-off (L1) were shown to be 2.23 m and 2.17 m for the $5^{th}$ and $6^{th}$ hurdles, respectively. For the distance from the hurdle to landing (L2), Pearson ($1^{st}$ rank) and Carruthers($2^{nd}$ rank) showed inconsistent patterns whereas Harper ($3^{rd}$ rank) and Porter ($4^{th}$ rank) showed consistent patterns. All althetes revealed similar 3 steps patterns between hurdles, which consisted of a shorter $1^{st}$ step, longer $2^{nd}$ step and shorter $3^{rd}$ step.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.5
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• pp.563-570
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• 2009

In the future, most military activities will be replaced by robots. Because of many dangerous factors in battlefield, reconnaissance should be performed by robot. Reconnaissance robot should be small for not being detected, be light and simple structure for personal portability and overcome unexpected rough terrain for mission completion. In case of small and light robot, it can't get enough friction force for movement. Therefore small reconnaissance robot need jumping function for movement. In this paper we proposed a biologically inspired jumping mechanism. And we adjusted moment and jumping angle by using four bar linkage, especially varying coupler length.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.8
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• pp.647-653
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• 2011

In this study, a method to measure the thickness of thin film by EDS (energy dispersive spectroscopy) is suggested. We have developed a model which calculates the thickness of thin film from the characteristic x-ray intensity ratio of the elements in thin film and substrate by considering incident electron beam energy, x-ray generation curve, backscattering and absorption of x-ray, take-off angle of x-ray and tilt angle of the sample. We obtained the relation curve between the film thickness measured experimentally and the x-ray intensity ratio of elements. The film thicknesses calculated from the model agrees quite well with those measured experimentally. Therefore, the thin film thickness can be measured rapidly and accurately by using the model developed in this study and the x-ray intensity ratio obtained in EDS analysis.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.135-144
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• 2006

This study was to investigate the kinematic analysis to score of the Yurchenko stretch skill according to phases in a horse vaulting. For this study, 8 male national gymnasts were participated in acquiring three dimensional kinematical imagining data with four Sony PD-150 video cameras After digitizing motion, the Direct Linear Transformation(DLT) technique was employed to obtain 3-D position coordinates. The kinematic factors of the distance, velocity and angle variable were calculated for Kwon3D 3.1. The following conclusions were drawn; 1) The COG resultant velocity of the less skilled group decreased in PRF phase because the less skilled group had a larger flexion-knee angle than the skilled group in BC phase, Because the less skilled group had larger flexion-shoulder angle than the skilled group in HTO phase, At blocking movement, the body inclined a moving direction. By means of it, COG lowered 2) The skilled group had a more rapid COG's vertical velocity than the less skilled group at HTD and HTO event in HC phase, because this was performed the blocking movement with body angle and contacted on a horse vaulting small and its time short by means of contacting hands on a horse vaulting quickly. Such blocking movement made the vertical up-flight movement easy at POF phase bringing out rapid COG's vertical velocity after take off a horse vaulting.