• Journal of the Korean Society of Radiology
• /
• v.8 no.2
• /
• pp.51-56
• /
• 2014

We analyzed how insole affects the dynamic stability and the balance while a body moves or stops. Specially we've sorted out variations of individual balance ability while we make a longitudinal arch stop artificially as a usual situation(just standing and putting one's weight). We found ten men and girls each with suitable feet for our experimentation as the subject of investigation and made individual insole for them by measuring medial longitudinal arch. Then we compared before and after movement of the power point of application and a pattern of COP using the Tetrax balance equipment. We found out it is better for balance ability when we wear insoles. It turned out to be helpful for increasing balance ability of body to use insole which supports medial longitudinal arch of longitudinal arch well.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.10
• /
• pp.809-819
• /
• 2020

In this study, the twist angle and wing planform shapes were selected as design variables and optimized to secure the stability of the flying-wing type UAV. Flying-wing aircraft has no separated fuselage and tails, which has advantages in aerodynamic characteristics and stealth performance, but it is difficult to secure the flight stability. In this paper, the sweep back angle and twist angle were optimized to obtain the lateral stability, the static margin and wing planform shapes were optimized to improve the longitudinal stability of the flying-wing, then effect of the twist angle was confirmed by comparing the stability of the shape with the winglet and the shape with the twist angle. In the optimization formulation, focusing on improving stability, constraints were established, objective functions and design variables were set, then design variable sensitivity analysis was performed using the Sobol method. AVL was used for aerodynamic analysis and stability analysis, and SQP was used for optimization. The CFD analysis of the optimized shape and the simulation of the dynamic stability proved that the twist angle can be applied to the improvement of the lateral stability as well as the stealth performance in the flying-wing instead of the winglet.

• Korean Journal of Human Ecology
• /
• v.5 no.2
• /
• pp.53-72
• /
• 1996

This article reviewed the research on factors associated with marital quality and stability. Three major categories of factors were described, including background and context, individual traits and behaviors, and couple interactional processes. This review highlighted findings from cross-sectional and longitudinal studies of the prediction of marital quality and stability. Particular attention was given to marital instruments and procedures that had a solid empirical foundation for understanding the concepts related to measure of marital quality and stability. Also, empirically based intervention programs that had been designed to prevent marital distress and divorce were investigated to figure out the relationship between communication factors and conflict resolution styles. Finally, three theoretical frameworks were drawn from empirical literatures, marital measurment instruments, and programs for marital strength to predict factors associated with the marital quality and stability. Recommendations for future research and implications were described.

• Journal of Mechanical Science and Technology
• /
• v.17 no.5
• /
• pp.654-667
• /
• 2003

This paper presents a consequence of the systematic approach to identify the aerodynamic parameters of an unmanned aerial vehicle (UAV) equipped with the automatic flight control system. A 3-2-1-1 excitation is applied for the longitudinal mode while a multi-step input is applied for lateral/directional excitation. Optimal time step for excitation is sought to provide the broad input bandwidth. A fully automated programmed flight test method provides high-quality flight data for system identification using the flight control computer with longitudinal and lateral/directional autopilots, which enable the separation of each motion during the flight test. The accuracy of the longitudinal system identification is improved by an additional use of the closed-loop flight test data. A constrained optimization scheme is applied to estimate the aerodynamic coefficients that best describe the time response of the vehicle. An appropriate weighting function is introduced to balance the flight modes. As a result, concurrent system models are obtained for a wide envelope of both longitudinal and lateral/directional flight maneuvers while maintaining the physical meanings of each parameter.

• Korean Journal of Childcare and Education
• /
• v.15 no.5
• /
• pp.23-45
• /
• 2019

Objective: The purpose of this study is to identify the longitudinal reciprocal relationship between young children's vocabulary ability and physical aggression in young children. Methods: Two waves of panel data(2013/2015) from the Panel Study of Korean Children were analyzed in this study by using an adapted version of Autoregressive cross-lagged modeling. A total of 306 five-year-old and seven-year-old preschoolers, and their mothers participated in the study. Autoregressive cross-lagged modeling for multiple groups was conducted by using AMOS 24.0. Results: First, vocabulary ability and physical aggression showed stability over time. Second, young children's vocabulary ability(t) had a statistically significant effect on physical aggression(t+1). Conclusion/Implications: This study confirmed the interrelationships of young children's vocabulary ability and physical aggression by examining longitudinal data using the longitudinal analysis method. This study highlights the importance of developing interventions to support language development with aggressive children. The results of the present study can be used as a source in developing policies for aggressive children and their parents.

• Journal of Aerospace System Engineering
• /
• v.15 no.5
• /
• pp.8-15
• /
• 2021

This paper describes a design method using an optimization technique to satisfy the longitudinal handling quality of high maneuverable jet aircraft. The dynamic inversion technique was applied to the target aircraft, and the control gain optimization satisfied the longitudinal short-period handling quality, however, the stability margin was not considered. If the stability margin is not satisfied, it is necessary to directly readjust the gains through trial and error methods for improvement. To improve this, an additional compensator and an optimization constraint were added to the control gain optimization procedure. In addition, the degree of handling quality satisfaction with the optimization result was reevaluated, and additional control evaluation criteria for the convergence of the time response and the steady state error that the flight performance requirement set as the optimization constraint cannot be reflected, and the results are described.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.25 no.2
• /
• pp.168-173
• /
• 2015

The flight control of aircraft, which has nonlinear time-varying dynamic characteristics depending on the various and unexpected external conditions, can be performed on two motions: longitudinal motion and lateral motion. In the longitudinal motion control of aircraft, pitch and trust are major control parameters and roll and yaw are control ones in the lateral motion control. Until now, a number of efficient and reliable control schemes that can guarantee the stability and maneuverability of the aircraft have been developed. Recently, the intelligent flight control scheme, which differs from the conventional control strategy requiring the various and complicate procedures such as the wind tunnel and environmental experiments, has attracted attention. In this paper, an intelligent longitudinal control scheme has been proposed utilizing Interval Type-2 fuzzy logic which can be recognized as a representative intelligent control methodology. The results will be verified through computer simulation with a F-4 jet fighter.

• The Journal of the Korea Contents Association
• /
• v.16 no.2
• /
• pp.231-242
• /
• 2016

This study analyses labor transition of middle-aged and elderly in Korea utilizing Korean Longitudinal Study of Ageing(KLoSA). Then it estimates the effects of perceived job stability for the middle-aged and elderly on poverty exit based on the age group simulation. The outcomes suggest that mid-50s and over are highly vulnerable to early retirement and they suffer from unstable employment and low possibility of re-employment. The logit analysis that simulates the effects of perceived job stability on poverty exit shows that mid-50s are more likely to get off the poverty than 65 and over when they have stable jobs. These implies that labor market policies should be designed in a tailor-made manner in consideration of the age group and its characteristics. This study also suggests the introduction of progressive labor policy measures that extends retirement age, that provides with job opportunities to middle-age and elderly, and that links employment and welfare under the umbrella of income security plan for the middle-aged and elderly.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.3
• /
• pp.274-279
• /
• 2010

The present work is to analyze the longitudinal static stability and the drop trajectory of fighter aircraft's external fuel tank, of which horizontal fin is modified as the 20% scale down size compared with the original one. The analytical results to the pitching stability of external fuel tank using a thin airfoil's aerodynamic force data show the corresponding tendency to results of wind tunnel experiment. Results of trajectory simulation by the 6 degree of freedom equations of motion, comparing with drop trajectories of wind tunnel experiment, are shown that aircraft's attitude affects strongly on horizontal movement but not on the vertical movement. Those results give the reliability to aircraft safety when the external fuel tank with the 20% reduced horizontal fins is released from aircraft based on the flight manual.

• Journal of Aerospace System Engineering
• /
• v.8 no.4
• /
• pp.24-31
• /
• 2014

The modern version of aircrafts is allowed to guarantee the superior handing qualities within the entire flight envelope by imposing the adequate stability and flying qualities on a target aircraft through the various techniques of flight control law design. Generally, the flight control law of the aircraft in service applies the various techniques of the verified control algorithm, such as dynamic inversion and eigenstructure assignment. The supersonic trainer employs the RSS(Relaxed Static Stability) concept in order to improve the aerodynamic performance in longitudinal axis and the longitudinal control laws employ the dynamic inversion with proportional-plus-integral control method. And, lateral-directional control laws employ the blended roll system of both beta-betadot feedback and simple roll rate feedback with proportional control method in order to guarantee aircraft stability. In this paper, the lateral-directional flight control law is designed by applying dynamic inversion control technique as a different method from the current supersonic trainer control technique, where the roll rate command system is designed at the lateral axis for the rapid response characteristics, and the sideslip command system is adopted at the directional axis for stability augmentation. The dynamic inversion of a simple 1st order model is applied. And this designed flight control law is confirmed to satisfy the requirement presented from the military specification. This study is expected to contribute to design the flight control law of KF-X(Korean Fighter eXperimental) which will proceed into the full-scale development in the near future.