• Journal of Communications and Networks
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• v.11 no.5
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• pp.464-472
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• 2009

In this paper, we propose a packet scheduling algorithm for cellular relay networks by considering relay selection, variation of channel quality, and packet delay. In the networks, mobile users are equipped with not only cellular but also user relaying radio interfaces, where base station exploits adaptive high speed downlink channel. Our proposed algorithm selects a user with good cellular channel condition as a relay station for other users with bad cellular channel condition but can get access to relay link with good quality. This can achieve flexible packet scheduling by adjusting transmission rates of cellular link. Packets are scheduled for transmission depending on scheduling indexes which are calculated based on user's achieved transmission rate, packet utility, and proportional fairness of their throughput. The performance results obtained by using computer simulation show that the proposed scheduling algorithm is able to achieve high network capacity, low packet loss, and good fairness in terms of received throughput of mobile users.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2437-2445
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• 1993

In this work, a new method is presented for generating the manipulator path which significantly reduces residual vibration under the torque constraints. The desired path is optimally designed so that the required movement can be achieved with minimum residual vibration. From the previous research works, the dynamic model had been established including both the link and the joint flexibilities. The performance index is selected to minimize the maximum amplitude of residual vibration. The path to be designed is developed by a combined Fourier series and polynomial function to satisfy both the convergence and boundary condition matching problems. The concept of correlation coefficients is used to select the minimum number of design variables, i.e. Fourier coefficients, the only ones which have a considerable effect on the reduction of residual vibration. A two-link Manipulator is used to evaluate this method. Results show that residual vibration can be drastically reduced by selecting an appropriate manipulator path to both of unlimited and torque-limited cases.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2222-2224
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• 2001

This paper presents the implementation of an efficient car tracking system based on Inverted DGPS (IDGPS) using mobile phone and internet for data communication link. The IDGPS technique, which may provide the same level of accuracy as DGPS, is subject to degradation in real time applications when transmission time delays occur in the communication links. Therefore, an effective communication system is the key element for successful application of the IDGPS. The combination of internet and mobile phones provides a high data rate, unlimited communication packet size, flexible data structure, and wide coverage without additional communication devices. An implementation of such a data link system is described. Field test results are included to evaluate the performance of the proposed system.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.496-500
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• 1993

This paper presents an end-point position control of 1-link flexible robot arm by the PID self-tuning fuzzy algorithm. The governing equation is derived by the extended Hamilton's principle and based on the Bernoullie-Euler beam theory. The governing equation is solved by applying the Laplace transform and the numerical inversion method. The arm is mounted on the translational mechanism driven by a ballscrew whose rotation is controlled by dcservomotor. Tip position is controlled by the PID self-tuning fuzzy algorithm so that it follows a desired position. This paper shows the experimental and theoretical results of tip dispalcement, and also shows the good effects reducing the residual vibration of the end-point.

• The Journal of Information Systems
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• v.15 no.3
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• pp.107-129
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• 2006

The purpose of this study is to provide and validate an IT cost model hi which we link among cost center, cost object and flexible cost driver. in order to accomplish this purpose, this study utilizes ethnographic research methodology. At first we develop the cost model where the flexible cost driver is the distribution basis of overhead cost. For each cost driver, unit cost management model is also proposed. Then we employ the structured design methodology to validate the model. Based on the IT Cost requirements of a case company, the IT cost system was designed and developed for its test. The result shows the model we developed in this study is appropriate for managing IT resources and further, can be used as a reference model for calculating chargeback rates of other departments and IT budget of IT department.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.12
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• pp.1045-1052
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• 2000

In this paper, we propose a method to apply the Input Shaping Technique (IST) to multi-input multi-output (MIMO) systems. In MIMO systems, there is a high possibility of multi-mode residual vibration. The IST filter designed for this multi mode may need a longer time to suppress the residual vibration. Previous works prove that we can shorten the time lag by using negative sequence. This negative sequence, however, causes another problem - it requires excessive control input. In this paper, we provide a remedy to reduce the size of control input by limiting the reference input by limiting the reference input and its derivative. The result of simulations and experiments on a 2 link flexible arm confirmed the effectiveness of the proposed method.

• Journal of KSNVE
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• v.7 no.3
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• pp.387-392
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• 1997

This paper concerns a SCARA robot with the flexible forearm linked to the rigid upper arm. The equations of motion are derived by the Lagrangian mechanics. For controller design, the perturbation approach is taken to separate the original equations of motion into linear equations describing small perturbed motions and nonlinear equations describing purely rigid motion of the robot. To effect the desired payload motion, open loop control inputs are determined based on the inverse dynamics of the latter. In order to reduce the positional error during maneuver, an active vibration suppression is done. To this end, a feedback control is designed for robustness against disturbance on the basis of the linear equations and the LQR theory modified to have a prescribed degree of stability. The proposed control scheme shows satisfactory performances in experiments as well as in numerical simulations.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.225-228
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• 1996

This paper concerns a SCARA type robot with the second arm flexible. Its equations of motion are derived by the Lagrangian mechanics. For controller design, the perturbation approach is taken to separate the original equations of motion into linear equations describing small perturbed motions and nonlinear equations describing purely rigid motion of the robot. To effect the desired payload motion, open loop control inputs are first determined based on the inverse dynamics of the latter. Next, in order to reduce the positional error during maneuver, an active vibration suppression is done. To this end, a feedback control is designed for robustness against disturbance on the basis of the linear equations and the LQR theory modified with a prescribed degree of stability. The numerical simulations results show the satisfactory control performance.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1761-1762
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• 2008

In this paper, we propose an adaptive neural control method to solve this problem. It is assumed that the model uncertainties of the robots dynamics, joint flexibility, and motor dynamics are unknown. The dynamic surface design method is applied, and all uncertainties in the robot and motor dynamics are compensated by using the adaptive function approximation technique. Simulation results for three-link electrically driven flexible-joint (EDFJ) manipulators are provided to validate the effectiveness of the proposed control system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.21-23
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• 2012

The process of building project for planning, designing, construction, maintenance, and waste disposal are related with each other. However, we have a difficulty for estimating building's LCC due not to be flexible each other. Therefore, we analyzed the boundary condition between the process of construction and maintenance, and analyzed the factor of segment. We also suggested the Link System for flexible relation.