• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.167-175
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• 2006

Directional stability is important performance in vehicle and tire design. The current methods to analyze this is generally based on linear concept. Using the existing concept, it cannot realistically explain the subjective assessment at all because it is hard to practically represent the nonlinear behaviour of a complex vehicle system in reality. In this paper, new method to analyze directional stability is introduced. At first, directional stability of vehicle is categorized into yaw, rear axle, and roll stability. In order to objectify these items, driver perceptual parameters based on subjective assessment are used. Using the perceptual parameters, it can successfully explain the transient maneuver of vehicle and extract objective parameters for directional stability. Finally, these objective parameters are successfully validated through two handling tests, lane change and severe lane change. The correlation results show that there exists a good correlation between subjective assessment and the proposed objective parameters.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.7
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• pp.621-630
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• 2006

The T-50 advanced trainer aircraft combines advanced aerodynamic features and a fly-by-wire flight control system in order to produce a stability and highly maneuverability. The flight control system both longitudinal and lateral-directional axes to achieve performance enhancements and improve stability. The T-50 employs the RSS 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 both beta-betadot feedback and simple roll rate feedback with proportional control method in order to guarantee aircraft stability. This paper details the design process of developing lateral-directional control laws, utilizing the requirement of MIL-F-8785C and MIL-F-9490D. And, this paper propose the analysis of aircraft characteristics such as dutch-roll mode, roll mode, spiral mode, gain and phase margin about gains for lateral-directional inner loop feedback.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1156-1163
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• 2010

The bi-directional high pile load test(BDH PLT) does not have weaknesses found in the existing bi-directional low pile load test(BDL PLT); it has strong economics, is unbound by load capacity limit and secures quality stability of working piles. In this study, Verification the field found a very high capacity level of stability and reliability of the BDH PLT, as well as outstanding field applicability. Field verifications reaffirmed the advantage of the BDH PLT device, which was capable of loading 90 MN capacities as maximum. It was also found to be durable enough to load high capacity with ease.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.511-514
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• 2005

This paper propose an advanced control strategy to improve vehicle handling and directional stability by integrating Active Front Steering(AFS) with Electronic Stability Program(ESP) . The effect of the integrated control system on the vehicle handling characteristics and directional stability is studied through a close loop computer simulation of and eight degree of freedom nonlinear vehicle model and driver model. Simulation results confirm the effectiveness of the proposed control system and the overall improvements in vehicle handling and directional stability

• Journal of International Society for Simulation Surgery
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• v.3 no.1
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• pp.9-11
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• 2016

Purpose In this paper we proposed bi-directional hierarchical regression for accurate human finger landmark detection with only using depth information.Materials and Methods Our algorithm consisted of two different step, initialization and landmark estimation. To detect initial landmark, we used difference of random pixel pair as the feature descriptor. After initialization, 16 landmarks were estimated using cascaded regression methods. To improve accuracy and stability, we proposed bi-directional hierarchical structure.Results In our experiments, the ICVL database were used for evaluation. According to our experimental results, accuracy and stability increased when applying bi-directional hierarchical regression more than typical method on the test set. Especially, errors of each finger tips of hierarchical case significantly decreased more than other methods.Conclusion Our results proved that our proposed method improved accuracy and stability and also could be applied to a large range of applications such as augmented reality and simulation surgery.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.160-165
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• 1998

In this paper, We discuss the directional stability of a Mini-bus with varying suspension design parameters. We analyzed the vehicle behavior during the cornering in a transient steering condition. We made a vehicle model by use of DADS, which is dynamic analysis software, in order to carry out many cases of simulation with varying design parameters. The effect of toe-geometry change to vehicle stability is evaluated by computer simulation and the actual test. In order to reduce the under steer characteristics of a mini-bus, the amount of toe geometry change should be less than current value.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.825-834
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• 2008

Nose chine shape optimization study has been performed to maximize the directional stability at high angle of attack supersonic flow. Various chine shapes are generated using super ellipse equation. By numerically investigating the directional stability characteristics of those shapes, the baseline configuration for the shape optimization has been selected using the three-dimensional Navier-Stokes equations. The configuration is represented by the NURBS curves which can adjust the surface geometry by the control points. The response surfaces are constructed to obtain optimum shape which has high directional stability characteristics and lift-to-drag ratio. From this study, an efficient configuration design and optimization process which utilizes the parameter-based configuration generation techniques and approximation method has been established, then 29% improvement of the directional stability by strong vortexes from chine nose is accomplished.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.32-41
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• 1995

In the analysis of metal forming processes by the finite element method, there are many numerical instabilities such as element locking, hourglass mode and shear locking. These instabilities may have a bad effect upon accuracy and convergence. The present work is concerned with improvement of stability and efficiency in two-dimensional rigid-plastic finite element method using various type of elemenmts and numerical intergration schemes. As metal forming examples, upsetting and backward extrusion are taken for comparison among the methods: various element types and numerical integration schemes. Comparison is made in terms of stability and efficiency in element behavior and computational efficiency and a new scheme of adaptive directional reduced integration is introduced. As a result, the finite element computation has been stabilized from the viewpoint of computational time, convergency, and numerical instability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.11
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• pp.948-956
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• 2012

This paper presents the computations of the longitudinal and directional stability derivatives for the SDM(Standard Dynamic Model). The static and dynamic derivatives are evaluated at once using forced harmonic oscillations in the pitch and yaw directions. For the numerical simulations, a 3-D Euler solver that uses a dual time stepping method for unsteady time accurate simulations is applied. This work investigates the variation of the derivatives in terms of the Mach number and the several motion parameters. Good agreement of the pitch and yaw stability derivatives with previously published numerical results and experimental results are observed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.2
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• pp.139-148
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• 2001

Phenomena induced by waves, such as overtopping, sediment transport, vibration/fluctuation and destruction of structures are highly influenced by the directionality of wave propagation. These phenomena are often dominated by non-linearity, and so hydraulic model experiments are widely adopted for stability analysis rather than numerical modeling, Thus, stability ofrubblc mound breakwaters(RMB) due to wavc directionality was experimentally investigated in this study. The incident wave angle $30^{\circ}$ was found more risky on the damage rate of RMB under directional regular waves, and the incident wave angle $40^{\circ}$ was found relatively risky under directional irregular waves. These results clarified the wave directionality effect on the stability ofRMB, These facts were found correspondent to the occurrence of the peak between $20^{\circ}$-$40^{\circ}$ with the directional frequency distribution of lIlO maximum water particle velocity.