• Journal of KSNVE
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• v.6 no.6
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• pp.791-800
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• 1996

Linear LQG controller has been investigated to control flexible link manipulators. The performance and complexity of these depend largely on the model upon which the controller is designed. In this study, the flexible modes of the link manipulator are considered to have uncertain parameters, which can be represented by random variable and these parameters are reflected on the weighting of performance. In this method, the exact modelling for the flexible modes is not necessary. The order of the resulting controller is much lower than the one based on a full model. Through numerical study, it is shown that the performance and the stability-robustness of the proposed controller reaches reasonably the one based on the full model.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.420-420
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• 2000

In this paper, we propose an adaptive controller using RBFN(radial basis function network) for robot manipulators The structure of the proposed controller consists of a RBFN and VSC-1 ike control. RBFN is used in order to approximate かon system, and VSC-like control to guarantee robustness On the basis of the Lyapunov stability theorem, we guarantee the stability for the total system. And the learning law of RBFN is established by the Lyapunov method, Finally, we apply the proposed controller to tracking control for a 2 link SCARA type robot manipulator.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1014-1022
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• 2009

A biped robot in locomotion can be regarded to be kinetically redundant in that the link-chain from its foot on the ground to its swing foot has more degrees of freedom that needed to realize stable bipedal locomotion. This paper proposes a new method to generate a trajectory for bipedal locomotion based on this redundancy, which directly generates a locomotion trajectory at the joint level unlike some other methods such as LIPM (linear inverted-pendulum mode) and GCIPM (gravity-compensated inverted-pendulum mode), each of which generates a trajectory of the center of gravity or the hip link under the assumption of the dominance of the hip-link inertia before generating the trajectory of the whole links at the joint level. For the stability of the trajectory generated in the proposed method, a stability condition based on the ZMP (zero-moment point) is used as a constraint as well as other kinetic constraints for bipedal motions. A 6-DOF biped robot is used to show how a stable locomotion trajectory can be generated in the sagittal plane by the proposed method and to demonstrate the feasibility of the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.9
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• pp.760-766
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• 2012

In this paper, we propose an efficient flooding process on link-state routing protocol. It is possible to exchange information using typical link-state routing protocol; for example, OSPF(Open Short Path First) or IS-IS(Intermediate system routing protocol) that floods LSA between nodes when the network topology change occurs. However, while the scale of network is getting bigger, it affects the network extensibility because of the unnecessary LSA that causes the increasing utilization of CPU, memory and bandwidth. An existing algorithm based on the Minimum spanning tree has both network instability and inefficient flooding problem. So, we propose algorithm for efficient flooding while maintaining network stability. The simulation results show that the flooding of proposed algorithm is more efficient than existing algorithm.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.247-250
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• 2003

In this paper, we propose a robust controller for motion control of n-link robot manipulators using visual feedback. The desired joint velocity and acceleration is obtained by the feature-based visual systems and is used in the joint velocity control loop for trajectory control of the robot manipulator. We design a robust controller that compensates for bounded parametric uncertainties of robot dynamics. The stability analysis of robust joint velocity control system is shown by Lyapunov Method. The effectiveness of the proposed method is shown by simulation results on the 5-link robot manipulators with two degree of freedom.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.180.3-180
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• 2001

In recent years, the remarkable development of communication network technology with the increasing demand of B-ISDN service helps the higg-speed ATM network to be applied a fully integrated global network. The considerable issue of high-speed communication network is a performance of service-link and stability of network queue. In this paper, we propose a feedback control algorithm and PID control method to improve the performance of service-link and stability of network queue and confirm upgraded traffic performance of the high-speed ATM network.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.89-96
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• 2003

An electro-hydraulic manipulator using hydraulic actuators has many nonlinear abetments, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to realize not only stable but also accurate trajectory control for the autonomous assembly tasks using hydraulic manipulators. In this report, we propose a two-degree-of-freedom control including parallel feedforward compensator (PFC) where PFC plays a very important role in the stability of a proposed control system. In the experimental results of the 6-link electro hydraulic manipulator, it is verified that the stability and the model matching performance are improved by using the proposed control method.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.64-72
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• 2004

An extension of interaction matrix formulation to the problem of system and disturbance identification for a plant that is corrupted by both process and output disturbances is presented. The teaming control develops controllers that learn to improve their performance at executing a given task, based on experience performing this task. The simplest forms of loaming control are based on the same concept as integral control, but operating in the domain of the repetitions of the task. This paper studies the use of such controllers in a decentralized system, such as a robot moving on the vertical plane with the controller for each link acting independently. The basic result of the paper is to show that stability and iterative precision of the learning controllers for all subsystems when the coupling between subsystems is turned off, assures stability of the decentralized teaming in the coupled system, provided that the sample time in the digital teaming controller is sufficiently short. The methods of teaming system are shown up for the iterative precision of each link.

• Journal of Korean Dental Science
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• v.8 no.2
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• pp.49-56
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• 2015

Purpose: The effect of accelerated aging on color stability of various dual-cured self-adhesive resin cements were evaluated in this study. Materials and Methods: Color stability was examined using three different brands of dual-cured self-adhesive resin cements: G-CEM LinkAce (GC America), MaxCem Elite (Kerr), and PermaCem 2.0 (DMG) with the equivalent color shade. Each resin cement was filled with Teflon mold which has 6 mm diameter and 2 mm thickness. Each specimen was light cured for 20 seconds using light emitting diode (LED) light curing unit. In order to evaluate the effect of accelerated aging on color stability, color parameters (Commission Internationale de l'Eclairage, CIE $L^*$, $a^*$, $b^*$) and color differences (${\Delta}E^*$) were measured at three times: immediately, after 24 hours, and after thermocycling. The $L^*$, $a^*$, $b^*$ values were analyzed using Friedman test and ${\Delta}E^*$ values on the effect of 24 hours and accelerated aging were analyzed using t-test. These values were compared with the limit value of color difference (${\Delta}E^*=3.7$) for dental restoration. One-way ANOVA and Scheff's test (P<0.05) were performed to analyze each ${\Delta}E^*$ values between cements at each test period. Result: There was statistically significant difference in comparison of color specification ($L^*$, $a^*$, $b^*$) values after accelerated aging except $L^*$ value of G-CEM LinkAce (P<0.05). After 24 hours, color difference (${\Delta}E^*$) values were ranged from 2.47 to 3.48 and $L^*$ values decreased and $b^*$ values increased in all types of cement and MaxCem Elite had high color stability (P<0.05). After thermocycling, color change's tendency of cement was varied and color difference (${\Delta}E^*$) values were ranged from 0.82 to 2.87 and G-CEM LinkAce had high color stability (P<0.05). Conclusion: Color stability of dual-cured self-adhesive resin cements after accelerated aging was evaluated and statistically significant color changes occurred within clinically acceptable range.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1125-1132
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• 2023

The importance of networks is gradually expanding in the battlefield environment. As time goes by, the types of tactical data links used in the Korean JTDLS are increasing, and the military's weapon systems equipped with tactical data link systems are increasing. Thorough quality verification is required to provide stable software to the wider battlefield. This study examines how to prepare an environment in which various simulation tests to verify the stability of the Korean JTDLS project can be conducted as diverse as possible using minimal physical space and Hardware resources. Through this, it is possible to improve the completeness of the project and secure the stability of the program, and it is intended to contribute to securing higher stability and reliability by securing maximum test capabilities in a limited test environment even in Linux based system project of a similar environment.