• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.3
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• pp.370-378
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• 2018

The mission data in missile systems should be quickly and reliably transmitted from a mission transmission device to a guidance control unit. The MIL-STD-1553B is one of the reliable communication standards, but its bit rate is generally limited to 1Mbps due to the intrinsic properties of its electrical design. Therefore, the bus controller needs to be optimized to efficiently transmit the mission data on the inevitably limited bit rate. This paper proposes an analytical approach based on sampling-based optimization methods to maximize the data throughput without data loss. The proposed approach was evaluated in the simulations with the data transmission model for the MIL-STD-1553B communication system. The results of the proposed methods were applied to a real-time system and showed that the proposed method was successfully performed.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.3
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• pp.133-144
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• 2000

Genetic Algorithm(GA) has been known as a method of solving large-scaled optimization problems with complex constraints in various applications. Since a major drawback of the GA is that it needs a long computation time, the hardware implementations of Genetic Algorithm Processors(GAP) are focused on in recent studies. In this paper, a hardware-oriented GA was proposed in order to save the hardware resources and to reduce the execution time of GAP. Based on steady-state model among continuos generation model, the proposed GA used modified tournament selection, as well as special survival condition, with replaced whenever the offspring's fitness is better than worse-fit parent's. The proposed algorithm shows more than 30% in convergence speed over the conventional algorithm in simulation. Finally, by employing the efficient pipeline parallelization and handshaking protocol in proposed GAP, above 30% of the computation speed-up can be achieved over survival-based GA which runs one million crossovers per second (1㎒), when device speed and size of application are taken into account on prototype. It would be used for high speed processing such of central processor of evolvable hardware, robot control and many optimization problems.

• Structural Engineering and Mechanics
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• v.86 no.5
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• pp.647-661
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• 2023

It is recognized that the installation of energy dissipation devices, such as the tuned mass damper (TMD), decreases the dynamic response of structures, however, the best parameters of each device persist hard to determine. Unlike many works that perform only a deterministic optimization, this work proposes a complete methodology to minimize the dynamic response of footbridges by optimizing the parameters of multiple tuned mass dampers (MTMD) taking into account uncertainties present in the parameters of the structure and also of the human excitation. For application purposes, a steel footbridge, based on a real structure, is studied. Three different scenarios for the MTMD are simulated. The proposed robust optimization problem is solved via the Circle-Inspired Optimization Algorithm (CIOA), a novel and efficient metaheuristic algorithm recently developed by the authors. The objective function is to minimize the mean maximum vertical displacement of the footbridge, whereas the design variables are the stiffness and damping constants of the MTMD. The results showed the excellent capacity of the proposed methodology, reducing the mean maximum vertical displacement by more than 36% and in a computational time about 9% less than using a classical genetic algorithm. The results obtained by the proposed methodology are also compared with results obtained through traditional TMD design methods, showing again the best performance of the proposed optimization method. Finally, an analysis of the maximum vertical acceleration showed a reduction of more than 91% for the three scenarios, leading the footbridge to acceleration values below the recommended comfort limits. Hence, the proposed methodology could be employed to optimize MTMD, improving the design of footbridges.

• Earthquakes and Structures
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• v.11 no.6
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• pp.943-966
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• 2016

Recently, magnetorheological elastomer (MRE) material and its devices have been developed and attracted a good deal of attention for their potentials in vibration control. Among them, a highly adaptive base isolator based on MRE was designed, fabricated and tested for real-time adaptive control of base isolated structures against a suite of earthquakes. To perfectly take advantage of this new device, an accurate and robust model should be built to characterize its nonlinearity and hysteresis for its application in structural control. This paper first proposes a novel hysteresis model, in which a nonlinear hyperbolic sine function spring is used to portray the strain stiffening phenomenon and a Voigt component is incorporated in parallel to describe the solid-material behaviours. Then the fruit fly optimization algorithm (FFOA) is employed for model parameter identification using testing data of shear force, displacement and velocity obtained from different loading conditions. The relationships between model parameters and applied current are also explored to obtain a current-dependent generalized model for the control application. Based on the proposed model of MRE base isolator, a second-order sliding mode controller is designed and applied to the device to provide a real-time feedback control of smart structures. The performance of the proposed technique is evaluated in simulation through utilizing a three-storey benchmark building model under four benchmark earthquake excitations. The results verify the effectiveness of the proposed current-dependent model and corresponding controller for semi-active control of MRE base isolator incorporated smart structures.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.9
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• pp.964-970
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• 2014

In this study we have developed an anthropomorphic robot hand and arm by using tendon-tubes which can be used for people's everyday life as a robot's dynamic power transmission device. Most previous robot hands or arms had critical problem on dynamic optimization due to heavy weight of power transmission parts which placed on robot's finger area or arm area. In order to resolve this problem we designed light-weighted robot hand and arm by using tendon-tubes which were consisted of many articulations and links just like human's hand and arm. The most prominent property of this robot hand and arm is reduction of the weight of robot's power transmission part. Reduction of weight of robot's power transmission parts will allow us to develop energy saving and past moving robot hands and arms which can be used for artificial arms. As a first step for real development in this study we showed structural design and demonstration of simulation of possibility of a robot hand and arm by tendon-tube. In the future research we are planning to verify practicality of the robot hand and arm by applying sensing and controlling method to a specimen.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4489-4493
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• 2014

LED light driving device has problems in efficiency and heating at higher than 150W. In addition, there is inconvenience in replacing the lighting device to another when W is not the same as the previous one. In this paper, a multi-channel LED light driver, driver embedded driver circuit in a multi-channel structure with a power system in the driver-interlocking structure was designed. With the auto control converter structure with a power efficiency above 93% and power factor above 0.98, the weight of the high efficiency LED lighting-actuating device in driver-interlocking structure, a driver in self-calibrating self-optimization structure. In this paper, at below 10% THD, the existing converter contrast weight was reduced by 40% or more.

• Journal of Korean Association for Spatial Structures
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• v.22 no.2
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• pp.39-46
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• 2022

Recently, machine learning is widely used to solve optimization problems in various engineering fields. In this study, machine learning is applied to development of a control algorithm for a smart control device for reduction of seismic responses. For this purpose, Deep Q-network (DQN) out of reinforcement learning algorithms was employed to develop control algorithm. A single degree of freedom (SDOF) structure with a smart tuned mass damper (TMD) was used as an example structure. A smart TMD system was composed of MR (magnetorheological) damper instead of passive damper. Reward design of reinforcement learning mainly affects the control performance of the smart TMD. Various hyper-parameters were investigated to optimize the control performance of DQN-based control algorithm. Usually, decrease of the time step for numerical simulation is desirable to increase the accuracy of simulation results. However, the numerical simulation results presented that decrease of the time step for reward calculation might decrease the control performance of DQN-based control algorithm. Therefore, a proper time step for reward calculation should be selected in a DQN training process.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.315-322
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• 2009

Penetration and installation of a new dynamic technology known as Flexible AC Transmission Systems (FACTS) in a practical and dynamic network requires and force expert engineer to develop robust and flexible strategy for planning and control. Unified Power Flow Controller (UPFC) is one of the recent and effective FACTS devices designed for multi control operation to enhance the power system security. This paper presents a dynamic strategy based on Particle Swarm Optimization (PSO) for optimal parameters setting of UPFC to enhance the system loadability. Firstly, we perform a multi power flow analysis with load incrementation to construct a global database to determine the initial efficient bounds associated to active power and reactive power target vector. Secondly a PSO technique applied to search the new parameters setting of the UPFC within the initial new active power and reactive power target bounds. The proposed approach is implemented with Matlab program and verified with IEEE 30-Bus test network. The results show that the proposed approach can converge to the near optimum solution with accuracy, and confirm that flexible multi-control of this device coordinated with efficient location enhance the system security of power system by eliminating the overloaded lines and the bus voltage violation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.13-20
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• 2013

In order to reduce seismic responses of a structure, additional dampers and vibration control devices are generally considered. Usually, control performance of additional devices are investigated for optimal design without variation of characteristics of a structure. In this study, multi-objective integrated optimization of structure-smart control device is conducted and possibility of reduction of structural resources of a building structure with smart top-story isolation system has been investigated. To this end, 20-story example building structure was selected and an MR damper and low damping elastomeric bearings were used to compose a smart base isolation system. Artificial earthquakes generated based on design spectrum of low-to-moderate seismicity regions are used for structural analyses. Based on numerical simulation results, it has been shown that a smart top-story isolation system can effectively reduce both structural responses and isolation story drifts of the building structure in low-to-moderate seismicity regions. The integrated optimal design method proposed in this study can provide various optimal designs that presents good control performance by appropriately reducing the amount of structural material and damping device.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1330-1333
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• 1997

In this paper, the optimal torque shaping is obtained for 3-axis rotation of a spacecraft. The true optimal 3-axis rotation of rigid spaeraft is first investigated via parameter optimization method with prescribed switching times. Input torque shape of the troque generating device mounted on the central hub is optimized using fourier Series expansion so that the spacecraft may slew while minimizing the vibration energy of flexible modes. Numerical results show that proposed method suggests a reference trahectory for open-loop control, and also verify that it can minimize the vibratory modes of the spacecraft during/after the rest-to-rest maneuver.