• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.181-184
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• 2017

This study analyzes the turn-on and turn-off transients of a metal-oxide-semiconductor field-effect transistor (MOSFET) with high-switching frequency systems. In these systems, the voltage distortion becomes serious at the output terminal of a Vienna rectifier by the turn-off delay of the MOSFET. The current has low-order harmonics through this voltage distortion. This paper describes the transient of the turn-off that causes the voltage distortion. The algorithm for reducing the sixth harmonic using a proportional-resonance controller is proposed to improve the current distortion without complex calculation for compensation. The reduction of the current distortion by high-switching frequency is verified by experiment with the 2.5-kW prototype Vienna rectifier.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.33-37
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• 2004

To meet an increasing demand for high performance in gun dynamic plant, both a precise and a fast response positioning are strongly required for the gun servomechanism control. A mode switching control(MSC) system, which includes a fine stabilizing controller, fast positioning one and a switching function, is widely used to meet this requirement. Stabilization is performed through PID controller, while proximate time optimal servo(PTOS) is used for target designation. Because gun dynamic have large damping comparing to acceleration, PTOS algorithm with damping is newly derived. This paper adopts the initial value compensation method that improve the transient response after switching. Some simulation results are given to show the effectiveness of our scheme.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.8
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• pp.25-32
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• 2011

Networks-on-chip (NoC) is emerging as a key technology to overcome severe bus traffics in ever-increasing complexity of the Multiprocessor systems-on-chip (MPSoC); however traditional electrical interconnection based NoC architecture would be faced with technical limits of bandwidth and power consumptions in the near future. In order to cope with these problems, a hybrid optical NoC architecture which use both electrical interconnects and optical interconnects together, has been widely investigated. In the hybrid optical NoCs, wormhole switching and simple deterministic X-Y routing are used for the electrical interconnections which is responsible for the setup of routing path and optical router to transmit optical data through optical interconnects. Optical NoC uses circuit switching method to send payload data by preset paths and routers. However, conventional hybrid optical NoC has a drawback that concurrent transmissions are not allowed. Therefore, performance improvement is limited. In this paper, we propose a new routing algorithm that uses circuit switching and adaptive algorithm for the electrical interconnections to transmit data using multiple paths simultaneously. We also propose an efficient method to prevent livelock problems. Experimental results show up to 60% throughput improvement compared to a hybrid optical NoC and 65% power reduction compared to an electrical NoC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.195-215
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• 2021

Multipath Transport Control Protocol (MPTCP) is a transport layer protocol that enables multiple TCP connections across various paths. Due to path heterogeneity, it incurs more energy in a multipath wireless network. Recent work presents a set of approaches described in the literature to support systems for energy consumption in terms of their performance, objectives and address issues based on their design goals. The existing solutions mainly focused on the primary system model but did not discourse the overall system performance. Therefore, this paper capitalized a novel stochastically multipath scheduling scheme for data and path capacity variations. The scheduling problem formulated over MPTCP as a stochastic optimization, whose objective is to maximize the average throughput, avoid network congestion, and makes the system more stable with greater energy efficiency. To design an online algorithm that solves the formulated problem over the time slots by considering its mindrift-plus penalty form. The proposed solution was examined under extensive simulations to evaluate the anticipated stochastic optimized MPTCP (so-MPTCP) outcome and compared it with the base MPTCP and the energy-efficient MPTCP (eMPTCP) protocols. Simulation results justify the proposed algorithm's credibility by achieving remarkable improvements, higher throughput, reduced energy costs, and lower-end to end delay.

• Journal of Power Electronics
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• v.12 no.1
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• pp.172-180
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• 2012

Z-source inverters (ZSI) are used to realize both DC voltage boost and DC-AC inversion in single stage with a reduced number of power switching devices. A traditional MPPT control algorithm provides a shoot-through interval which should be inserted in the switching waveforms of the inverter to output the maximum power to the Z-network. At this instant, the voltage across the Z-source capacitor is equal to the output voltage of a PV array at the maximum power point (MPP). The control of the Z-source capacitor voltage beyond the MPP voltage of a PV array is not facilitated in traditional MPPT algorithms. This paper presents a unified MPPT control algorithm to simultaneously achieve MPPT as well as Z-source capacitor voltage control. Development and implementation of the proposed algorithm and a comparison with traditional results are discussed. The effectiveness of the proposed unified MPPT control strategy is implemented in Matlab/Simulink software and verified by experimental results.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.3
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• pp.293-299
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• 2009

This paper discusses an autonomous navigation system for urban environments. For the localization of the robot, EKF (Extended Kalman Filter) algorithm is used with odometry, angle sensor, and DGPS (Differential Global Positioning System) measurement. Especially in an urban environment, DGPS is often blocked by buildings and trees and the resulting inaccurate positioning prevents the robot from safe and reliable navigation. In addition to the global information from DGPS, the local information of the curb on the roadway is used to track a route when the global DGPS information is inaccurate. For this purpose, curb detection algorithm is developed and implemented in the developed navigation algorithm. Four different types of navigation strategies are developed and they are switched to adapt to different localization conditions according to the availability of DGPS and the existence of the curbs on the roadway. The experimental results show that the designed switching strategy improves the navigation performance adapting to the environment conditions.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.309-313
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• 2001

A single-phase bi-directional inverter with a diode bridge-type resonant circuit to implement ZVT(Zero Voltage Transition) switching is proposed. It is shown that the polarized ramptime current control algorithm, a method that belongs to the family of ZACE(Zero Average Current Error) methods, is a suitable technique to integrate with a typical single-phase ZVT inverter. The proposed current control algorithm is analyzed to design the circuit with auxiliary switch which can operate with ZVT for the main power switch. The simulation results would be shown to verify the proposed current algorithm to turn the main power switch on with ZVT and to operate the inverter bi-directionally

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1382-1385
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• 2007

In this paper, we study about the measuring algorithm that can implement Structural Health Monitoring (SHM) more efficiently by two measurement methods using smart sensor. Through the impedance measurement method, the damage condition of structures on wide area is monitored first, and then it changes the mode to guided wave measurement mode by mode switching algorithm when impedance measurement mode detects abnormal signals. Efficient handling of the real-time data would be available by analyzing location and shape of damage through guided wave measurement.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.4
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• pp.227-235
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• 2011

This paper describes a PMSM control algorithm for realizing a low-cost motor drive system using a general purpose microcontroller. The proposed sensorless algorithm consists of the current observer and the sensorless scheme based on instantaneous reactive power. Also the control board system is not the high-cost DSP(digital signal processor) system but the general purpose microcontroller and it allows to reduce the unit cost of the motor system. However the clock frequency of the proposed microcontroller is one-fifths for the clock frequency of the DSP. In addition, the switching frequency must be selected as the lower frequency because of complex mathematic modeling of the sensorless algorithm. the low switching frequency augments the noise of the motor and might make accurate speed control impossible. Thus this paper proposes the optimization method to supplement the drawback of the general purpose microcontroller and the usefulness of the proposed method is verified through the experiment.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.149-152
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• 2001

A Single-phase bi-directional inverter Using a diode bridge-type resonant circuit to implement ZVT(Zero Voltage Transition) switching is Presented. It is shown that the ZACE(Zero Average Current Error) algorithm based polarized ramptime current control can provide a suitable interface between diode bridge-type resonant circuit DC link and the inverter. The current control algorithm is analyzed about how to design the circuit with analyzed switch which m ZVT operation for the main power switch The simulation and experimental results would be shown to verify the proposed current algorithm, because the main power switch is turn on with ZVT and the bi-directional inverter is operated.