• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.228-236
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• 2004

In this paper. we present a neuro-fuzzy controller which unifies both fuzzy logic and multi-layered feed forward neural networks. Fuzzy logic provides a means for converting linguistic control knowledge into control actions. On the other hand. feed forward neural networks provide salient features. such as learning and parallelism. In the proposed neuro-fuzzy controller. the parameters of membership functions in the antecedent part of fuzzy inference rules are identified by using the error back propagation algorithm as a learning rule. while the coefficients of the linear combination of input variables in the consequent part are determined by using the least square estimation method. Finally. the effectiveness of the proposed controller is verified through computer simulation for an inverted pole system.

• Progress in Superconductivity
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• v.1 no.1
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• pp.51-55
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• 1999

A Ni/Ag/Stainless steel 310S(SS310S) multi-layer sheet has been fabricated by a combination of vacuum brazing, cold rolling and texture annealing processes. After heat-treating the thin Ni/Ag/SS310S multi-layer sheet at $900^{\circ}C$ for 2h, development of (100)<001>cube texture on Ni surface was revealed by (111) pole figure. Quantitative chemical analysis was made by EPMA for the cross-section of the Ni/Ag/SS310S multi-layer sheet. EPMA results showed that Ag diffusion into the Ni layer, which may suppress the cube texture development, was negligible. A small amount of Cr atoms were detected in the Ni layer. It showed that Ag can be used as a chemical barrier of alloying element atoms in Ni layer for the Ni/Ag/SS310S multi-layer sheet and a strong cube texture was developed for the Ni layer in the Ni/Ag/SS310S multi-layer sheet.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.10
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• pp.629-644
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• 2014

The goal of this paper is to consider a co-design approach between time delay compensation and the message scheduling for CAN-Based Networked Control Systems (NCS). First we propose a hybrid priority scheme for the message scheduling in order to improve the Quality of Service (QoS). Second we present the way to calculate the closed-loop communication time delay and then compensate this time delay using the pole placement design method in order to improve the Quality of Control (QoC). The final objective is the implementation of a co-design which is the combination of the compensation for communication time delays and the message scheduling in order to have a more efficient NCS design.

• Journal of Magnetics
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• v.18 no.4
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• pp.460-465
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• 2013

This paper deals with an approach for the initial design of a permanent magnet motor for turrets with large diameters. The proposed design techniques are introduced as three stages. The first is the selection of a pole-slot combination, the second is the selection of the rotor topology, and the last is choosing the outermost dimensions. In every stage, a useful technique is described with considerations for effective fabrication and motor performance, and magnetic field computation is performed using the finite element method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.224-228
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• 2004

The switched reluctance motor(SRM) drive system provides a good adjustable speed and torque characteristics. SRM has the possibility of maintaining full power over a wide speed range. So, many attempts are being done from home appliances to industrial machinery and tools. Especially, the traction drive of SRM is one of a good application due to it's torque characteristics. However, because of the switching mechanism, it has some disadvantage of noise and vibration. It is difficult to adopt to an appliance demanding silence. A noise simulations and test of 3-phase 6/4, 6/8 and 12/8 SRM were done in other to compare each other. The test results show that 12/8 SRM has good noise characteristics.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.3
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• pp.301-311
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• 1990

A multiple controller structure consisting of a typical feedback controller and an additive redundant controller is proposed for enhancing the reliability of the control system. For the case where the main controller is chosen as a pole assignment controller with input/output measurements and the redundant controller as the Model Reference Adaptive Controller (MRAC) whose reference model is the closed-loop combination of the plant and the main controller, it is proven that the tracking error between the command input and plant output converges to zero under failure in one of the controllers or parameter perturbations of the plant, and further that the reliability measured by Mean Time To Failure (MTTF) is greater than that of the system with only a single main controller. A simulation Example is provided to illustrate reliable operation of the proposed control system against the controller failure.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1886-1900
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• 2018

This paper proposes a confronting feedback control structure and controllers for positive output elementary super lift Luo converters (POESLLCs) working in discontinuous conduction mode (DCM). The POESLLC offers the merits like high voltage transfer gain, good efficiency, and minimized coil current and capacitor voltage ripples. The POESLLC working in DCM holds the value of not having right half pole zero (RHPZ) in their control to output transfer function unlike continuous conduction mode (CCM). Also the DCM bestows superlative dynamic response, eliminates the reverse recovery troubles of diode and retains the stability. The proposed control structure involves two controllers respectively to control the voltage (outer) loop and the current (inner) loop to confront the time-varying ON/OFF characteristics of variable structured systems (VSSs) like POESLLC. This study involves two different combination of feedback controllers viz. the proportional integral controller (PIC) plus sliding mode controller (SMC) and the fuzzy logic controller (FLC) plus SMC. The state space averaging modeling of POESLLC in DCM is reviewed first, then design of PIC, FLC and SMC are detailed. The performance of developed controller combinations is studied at different working states of the POESLLC system by MATLAB-Simulink implementation. Further the experimental corroboration is done through implementation of the developed controllers in PIC 16F877A processor. The prototype uses IRF250 MOSFET, IR2110 driver and UF5408 diodes. The results reassured the proficiency of designed FLC plus SMC combination over its counterpart PIC plus SMC.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.459-466
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• 2022

Switching surges are a common type of phenomenon that occur on any sort of power system network. These are more pronounced on long transmission lines and in high voltage converter stations. At AC/DC hybrid transmission lines, the insulation coordination of such lines is mainly dictated by the peak level of switching surges, the most dangerous of which include three phase line energization and AC/DC converter station. The power system structure consist of AC/DC hybrid transmission lines which is combination of AC 765kV and ±500kV HVDC 1 bipole system for contingency analysis. The power system under study and its components are simulated using EMTDC software package, the effects of the various AC/DC mixing power lines are reviewed. The developed models of EMTDC conversion lines based on combination of AC/DC system are simulated and the characteristics of switching surge over-voltage from its results are discussed.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.72.3-72.3
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• 2015

We present the mid-infrared (MIR) luminosity function (LF) of local (z < 0.3) star forming (SF) galaxies based on the AKARI's NEP-Wide Survey data. We utilized a combination of the NEP-Wide point source catalogue containing a large number (114,000) of infrared (IR) sources distributed over the wide (5.4 sq. deg) field and spectroscopic redshift (z) data for 1790 selected targets obtained by optical follow-up surveys with MMT/Hectospec and WIYN/Hydra. The AKARI's continuous $2{\sim}24{\mu}m$ wavelength coverage and the spectroscopic redshifts for sample galaxies enable us to derive accurate spectral energy distributions (SEDs) in the mid-infrared. We carried out SED-fit analysis and employed 1/Vmax method to derive the mid-IR (e.g., $8{\mu}m$, $12{\mu}m$, and $15{\mu}m$ rest-frame) luminosity functions. Our results for local galaxies from the NEP region generally consistent with various previous works for other fields over wide luminosity ranges. The comparison with the results of the NEP-Deep data implies the luminosity evolution from higher redshifts towards the present epoch. We attempted to fit our derived LFs to the double power-laws and present the resulting power indices. We also examined the correlation between mid-IR luminosity and total IR luminosity.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1555-1566
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• 2018

Proportional capacitor-current-feedback active damping (AD) is a common damping method for the resonance of LCL-type grid-connected inverters. Proportional capacitor-current-feedback AD behaves as a virtual resistor in parallel with the capacitor. However, the existence of delay in the actual control system causes impedance in the virtual resistor. Impedance is manifested as negative resistance when the resonance frequency exceeds one-sixth of the sampling frequency ($f_s/6$). As a result, the damping effect disappears. To extend the system damping region, this study proposes a virtual resistor-inductor-capacitor (RLC) AD method. The method is implemented by feeding the filter capacitor current passing through a band-pass filter, which functions as a virtual RLC in parallel with the filter capacitor to achieve positive resistance in a wide resonance frequency range. A combination of Nyquist theory and system close-loop pole-zero diagrams is used for damping parameter design to obtain optimal damping parameters. An experiment is performed with a 10 kW grid-connected inverter. The effectiveness of the proposed AD method and the system's robustness against grid impedance variation are demonstrated.