• Journal of Advanced Marine Engineering and Technology
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• v.27 no.4
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• pp.526-534
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• 2003

Motions of animals and gymnasts in the air as well as free flying space robots without thruster are subject to nonholonomic constraints generated by the law of conservation of angular momentum. The interest in nonholonomic control problems is motivated by the fact that such systems can not stabilized to its equilibrium points by the smooth control input. The purpose of this paper is to derive analytical posture control laws for free flying objects in the air. We propose a control method using bang-bang control for trajectory planning of a 3 link mechanical system with initial angular momentum. We reduce the DOF (degrees of freedom) of control object in the first control phase and determine the control inputs to steer the reduced order system from its initial position to its desired position. Computer simulation for a motion planning of an athlete approximated by 3 link is presented to illustrate the effectiveness of the Proposed control scheme.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.1
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• pp.63-69
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• 2005

The motion of animals and gymnasts in the air as well as free flying space robots without thrusters are subjected to nonholonomic constraints generated by the law of conservation of angular momentum. The purpose of this paper is to derive analytical posture control laws for free flying objects in the air. We propose the bang-bang control method for trajectory planning of a 3 link mechanical system with initial angular momentum. This technique is used to reduce the DOF (degrees of freedom) at first switching phase and to determine the control inputs to steer the reduced order system to the desired position. Computer simulations for motion planning of an athlete approximated by 3 link, namely platform diving, are provided to verify the effectiveness of the proposed control scheme.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.519-524
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• 1998

This paper presents a robust control scheme of free-joint manipulators to overcome actuator failures and uncertain-ties in Cartesian space where tasks are planned. The control scheme has the adaptation law for the upper bound on the norm of uncertainties through the Lyapunov function approach. To solve the dynamic singularity problem in the controller, the singular and nonsingular regions are investigated based on a computer simulation. Then a singularity-free Cartesian trajectory planning is achieved in order to guarantee the availability of the control scheme. To illustrate the validity of the proposed control scheme, simulation results for a three-link planar robot arm with a free joint are shown.

• Journal of Information Processing Systems
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• v.19 no.3
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• pp.370-376
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• 2023

Aiming at the problems of low image enhancement accuracy, long enhancement time and poor image quality in the traditional robot sequence motion image enhancement methods, an adaptive enhancement method for robot sequence motion image is proposed. The feature representation of the image was obtained by Karhunen-Loeve (K-L) transformation, and the nonlinear relationship between the robot joint angle and the image feature was established. The trajectory planning was carried out in the robot joint space to generate the robot sequence motion image, and an adaptive homomorphic filter was constructed to process the noise of the robot sequence motion image. According to the noise processing results, the brightness of robot sequence motion image was enhanced by using the multi-scale Retinex algorithm. The simulation results showed that the proposed method had higher accuracy and consumed shorter time for enhancement of robot sequence motion images. The simulation results showed that the image enhancement accuracy of the proposed method could reach 100%. The proposed method has important research significance and economic value in intelligent monitoring, automatic driving, and military fields.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.8
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• pp.573-580
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• 2020

One of challengeable problems of multi-agent systems is a positioning control. Augmented Cucker-Smale model is using for controlling position and velocity of the multi-agent system. The original model applies same coefficients to all agents in same group, so that does not consider characteristic of each agent. To enhance performance of the original model, this paper transforms original coefficients to Mahalanobis distance coefficients that reflects an initial distribution of multi-agent systems and applies statistical degrees of freedom. This paper not only confirms tendency of enhanced performance of the suggested model by using monte-carlo simulation, but also additionally compares trajectory of the original model with the suggested model to confirm coefficients of Mahalanobis distance performing correctly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.799-804
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• 2001

Nonlinear normal mode (NNM) vibration, in a nonlinear dual mass Hamiltonian system, which has 6th order homogeneous polynomial as a nonlinear term, is studied in this paper. The existence, bifurcation, and the orbital stability of periodic motions are to be studied in the phase space. In order to find the analytic expression of the invariant curves in the Poincare Map, which is a mapping of a phase trajectory onto 2 dimensional surface in 4 dimensional phase space, Whittaker's Adelphic Integral, instead of the direct integration of the equations of motion or the Birkhotf-Gustavson (B-G) canonical transformation, is derived for small value of energy. It is revealed that the integral of motion by Adelphic Integral is essentially consistent with the one obtained from the B-G transformation method. The resulting expression of the invariant curves can be used for analyzing the behavior of NNM vibration in the Poincare Map.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.6
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• pp.461-467
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• 2014

This paper investigates using small UAVs as communications relay nodes for expanding communications links and improving communications quality, primarily for a fleet of ground or navy vessels. An airborne relay in ground/maritime space can effectively connect to units operating over the horizon, beyond normal communication range, or under limited satellite communication environment. Even if the equipment development is mature for communications relay, where to locate UAVs for efficient relay is still a pending question. With this background, this paper will develop high-level deployment algorithms to optimize the location of UAVs for improving the connectivity of a wireless network among a fleet of ground or navy vessels.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.156-165
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• 2015

A survivability-analysis program has been developed to analyze the ground collision risk of atmospheric reentry objects, such the upper stages of a launch vehicle or satellites, which move at or near the orbital velocity. The aero-thermodynamic load during the free fall, the temperature variation due to thermal load, and the phase shift after reaching the melting point are integrated into the 3 degree-of-freedom trajectory simulation of the reentry objects to analyze the size and weight of its debris impacting the ground. The analysis results of the present method for simple-shaped objects are compared with the data predicted by similar codes developed by NASA and ESA. Also, the analysis for actual reentry orbital objects has been performed, of which results are compared with the measurement data.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.713-719
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• 2014

When multiple reactions of quaternary mixtures take place in a reactive distillation column, the behavior of composition trajectory is analyzed by a visual-aided method. By adding additional vectors of multiple reactions and visualizing them in composition space, the composition of each component and extent of each reaction on an arbitrary stage can be easily estimated in terms of the composition trajectory and reaction cascade difference points. Moreover, for a given operating conditions, the number of total stages and position of optimum reaction zone can be determined by the visual-aided method. In this study, ethylene glycol synthesis with a side reaction is taken as an example and analyzed by the proposed graphical method. Through this method, the quaternary reactive distillation with multiple reactions can be analyzed without numerous experiments and simulations.

• Fire Science and Engineering
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• v.33 no.4
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• pp.121-129
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• 2019

The Chemical Control Act of 2015 was enhanced to ensure the safe management of hazardous chemicals. In particular, there have been substantial changes in the standards for the installation and management of handling facilities for manufacturing and storing hazardous chemicals. However, some standards for handling facilities are difficult to implement due to a lack of physical space or because of safety accidents during facility improvements. Therefore, the Safety assessment system (SAS) has been operating for such facilities since 2018. This study developed a leakage trajectory evaluation module that can easily evaluate the outside of a dike for safety evaluation. We analyzed two case studies on a dike for hydrochloric acid and sulfuric acid storage tanks with this module and suggest a reasonable plan for the facility. We believe that it will be possible to more easily submit SAS reports at chemical plants by using this evaluation module. This study is expected to contribute to the improvement of the safety design of hazardous chemical handling facilities.