• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.489-496
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• 2018

In this paper, a performance comparison of dynamic TDMA and fixed TDMA in tactical data link system is conducted. The performance metric include: delay, queue size and system throughput. To perform comparison of two TDMA schemes, we adopt the modified M/D/1 queueing model. Computer simulation is also performed to verify conducted analytical results.

• Journal of Mechanical Science and Technology
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• v.16 no.1
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• pp.13-23
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• 2002

This paper presents inverse kinematic and dynamic analyses of HexaSlide type six degree-of-freedom parallel manipulators. The HexaSlide type parallel manipulators (HSM) can be characterized as an architecture with constant link lengths that are attached to moving sliders on the ground and to a mobile platform. In the inverse kinematic analyses, the slider and link motion (position, velocity, and acceleration) is computed given the desired mobile platform motion. Based on the inverse kinematic analysis, in order to compute the required actuator forces given the desired platform motion, inverse dynamic equations of motion of a parallel manipulator is derived by the Newton-Euler approach. In this derivation, the joint friction as well as all link inertia are included. Relative importance of the link inertia and joint frictions on the computed torque is investigated by computer simulations. It is expected that the inverse kinematic and dynamic equations can be used in the computed torque control and model-based adaptive control strategies.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3236-3238
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• 1999

This paper proposes a new face recognition technique in the dynamic link architecture which shows robustness against size variation and distortion. The face recognition technique in the dynamic link architecture so far was not appropriate for the recognition of various size of faces because of the fixed size of the graph and the fixed value of a of the Gabor filter not considering the size of the face. The proposed face recognition algorithm can represent the input facial image by a suitable size of labeled graph, and it can also adjust the dilation width and the height of the vibrating amplitude of the Gabor filter, thus face recognition in the dynamic link architecture is even applicable regardless of the size of the face.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.715-725
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• 2000

As a link composition of a double link type level luffing jib crane was determinated through the link composition design, the design to be considered will be computations of the luffing trajectory deviation at the fly jib tip and the required luffing device capacity. This paper is a study regarding the static and dynamic analysis for a mechanism of the crane. The objective of the static analysis is to determinate the capacity and the dimension of luffing device when the crane selfload, rated hoisting load, wind load and inertia force are applied on the crane. The objective of dynamic analysis is to compute the luffing trajectory deviation, velocity and inertia force due to luffing acceleration for each link. All analyses are performed by computer programs. The reliability of the program was checked by results from analyses of the related commercial package. It is expected that the productivity and reliability of the design can be improved by this program which can rapidly and exactly deal with static and dynamic analysis for a given link composition of the crane.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.11
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• pp.902-910
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• 2013

The most representative research network in Korea, KREONET, has developed DynamicKL, an advance reservation based Network Service Agent (NSA) for user driven virtual circuit services. DynamicKL provides reservation, provisioning, release, termination, and inquiry web services for network resources by using an open standard network service interface (NSI), as well as web services for network resources by using a GUI interface. In addition, it has the RICE interface to support a protection management function per VC for virtual circuits and reservations. In this article, a protection management per VC for provisioned VCs and reservations is addressed in the DynamicKL framework, as a contribution to the VC protection management issue, which results in more manageable and reliable VC services compared to other advance reservation frameworks. An administrator can detect successful or unsuccessful VC protections in the event of a primary link failure and successful or unsuccessful VC retrievals after a primary link repair, by using RICE.

• Journal of Power Electronics
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• v.15 no.3
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• pp.763-774
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• 2015

This study investigates the inherent influence of a DC-link voltage controller on both DC-link voltage control and the compensation performance of a three-phase, four-wire shunt active power filter (APF). A nonlinear variable-parameter DC-link voltage controller is proposed to satisfy both the dynamic characteristic of DC-link voltage control and steady-state compensation performance. Unlike in the conventional fixed-parameter controller, the parameters in the proposed controller vary according to the difference between the actual and the reference DC-link voltages. The design procedures for the nonlinear voltage controller with variable parameters are determined and analyzed so that the proposed voltage controller can be designed accordingly. Representative simulation and experimental results for the three-phase, four-wire, center-spilt shunt APF verify the analysis findings, as well as the feasibility and effectiveness of the proposed DC-link voltage controller.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.865-874
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• 2016

This research is concerned with the experimental investigation on the vibrations of a flexible two-link system for verifying the theoretical result from simplified equations of motion for the system along with the kinematical synthesis are proposed to simulate the elastic vibrations of a previous study. The structure consists of flexible two-links; The link 2 is attached to the end of the link 1. The link 1 is made of composite fiber reinforced polymer and the link 2 is an aluminum beam. In order to verify the theoretical result, a flexible two-link system operated by the AC and RC servo motors was constructed. Experimental results show that the dynamic modeling approach and the kinematical synthesis proposed in this paper are effective.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.4
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• pp.219-226
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• 2019

One of the most widely studied protocols for tactical ad-hoc networks is Optimized Link State Routing Protocol (OLSR). As for OLSR research, most research work focus on reducing control traffic overhead and choosing relay point. In addition, because OLSR is mostly dependent on link detection and propagation, dynamic Hello timer become research challenges. However, different timer interval causes imbalance of link validity time by affecting link lifetime. To solve this problem, we propose a weighted topology graph model for constructing a robust network topology based on the link validity time. In order to calculate the link validity time, we use control message timer, which is set for each node. The simulation results show that the proposed mechanism is able to achieve high end-to-end reliability and low end-to-end delay in small networks.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.4
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• pp.123-138
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• 2009

This study examined the first- and second-best pricing by stable dynamics in congested transportation networks. Stable dynamics, suggested by Nesterov and de Palma (2003), is a new model which describes and provides a stable state of congestion in urban transportation networks. The first-best pricing in user equilibrium models introduces user-equilibrium in the system-equilibrium by tolling the difference between the marginal social cost and the marginal private cost on each link. Nevertheless, the second-best pricing, which levies the toll on some, but not all, links, is relevant from the practical point of view. In comparison with the user equilibrium model, the stable dynamic model provides a solution equivalent to system-equilibrium if it is focused on link flows. Therefore the toll interval on each link, which keeps up the system-equilibrium, is more meaningful than the first-best pricing. In addition, the second-best pricing in stable dynamic models is the same as the first-best pricing since the toll interval is separately given by each link. As an effect of congestion pricing in stable dynamic models, we can remove the inefficiency of the network with inefficient Braess links by levying a toll on the Braess link. We present a numerical example applied to the network with 6 nodes and 9 links, including 2 Braess links.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1321-1328
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• 2009

In this paper, an electromagnetic force driving actuator (EMFA) and three-link mechanism are proposed as a driving mechanism and connection device for low voltage air circuit breaker (ACB). As the result of dynamic characteristic analysis, the actuator and link mechanism are designed from the simulation and manufactured. The magneitc field of the EMFA is analyzed using the finite element method (FEM). The dynamic characteristic analysis with calculation of the circuit equation and kinetical equation is performed by the time difference method (TDM). Also, the result of the analysis is verified through the experiment of the fabrication model. In this paper, the EMFA size is smaller than the actuator for high voltage circuit breaker. Thus, the dynamic characteristic is analyzed with end-winding inductance that is calculated by the same method which is applied on the circle type end-winding of motors. The designed model for 1600 ampere-frame ACB and the three-link mechanism for connecting contact part with actuating part are manufactured. It is confirmed that the three-link mechanism is possible for improving the circuit breaker efficiency and reducing the size of the EMFA. It is proved that the improved 2-D analysis is more accurate than established method.