• Journal of Electrical Engineering and Technology
• /
• v.13 no.4
• /
• pp.1549-1557
• /
• 2018

Optimizing the design of large-scale electric machines based on nonlinear finite element analysis (FEA) requires longer computation time than other applications of FEA, mainly due to the huge size of the machines. This paper addresses a new region decision method (RDM) with mesh adaptive direct search (MADS) for the optimal design of wind generators in order to reduce the computation time. The validity of the proposed algorithm is evaluated using Rastrigin and Goldstein-Price benchmark function. Moreover, the algorithm is employed for the optimal design of a 5.6MW interior permanent magnet synchronous generator to minimize the torque ripple. Additionally, mechanical stress analysis as well as electromagnetic field analysis have been implemented to prevent breakdown caused by large centrifugal forces of the modified design.

• Smart Structures and Systems
• /
• v.9 no.6
• /
• pp.549-563
• /
• 2012

Theoretical analysis is performed on a multi-mode energy harvester design with focus on the first two vibration modes. Based on the analysis, a modification is proposed for designing a novel adaptive multi-mode energy harvester. The device comprises a simply supported beam with distributed mass and piezoelectric elements, and an adaptive damper that provides a 180 degree phase shift for the motions of two supports only at the second vibration mode. Theoretical analysis and numerical simulations show that the new design can efficiently scavenge energy at the first two vibration modes. The energy harvesting capability of the multi-mode energy harvester is also compared with that of a cantilever-based energy harvester for single-mode vibration. The results show that the energy harvesting capacity is affected by the damping ratios of different designs. For fixed damping ratio and design dimensions, the multi-mode design has higher energy harvesting capacity than the cantilever-based design.

• The KIPS Transactions:PartC
• /
• v.9C no.3
• /
• pp.399-406
• /
• 2002

We consider design of multiservice network link, in which connections of constant- and adaptive-rate services arrive and leave dynamically. We propose performance analysis and design methods of these dynamic multiservice networks. A multiservice network link is modeled by a Markov chain, and data rates for adaptive-rate connections are derived using QBD (Quasi-Birth-Death) processes and matrix-geometric equations. We estimate average number of adaptive-rate connections, average data rate and average connection delay. The performance of constant-rate connections is determined from the blocking probability of the connections. Based on the performance of constant-and adaptive- rate connections, we propose a design methods of a network link to satisfy performance requirements of constant- and adaptive-rate connections (data rates, delay, blocking probability). Our methods can be used for the analysis and design of network switch supporting dynamic data and voice (video) traffic simultaneously.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.122-127
• /
• 2003

In this paper, an adaptive predistortion scheme is proposed to compensate nonlinear distortions caused by high power amplifiers (HPA) in OFDM systems. A complex Wiener-Hammerstein model (WHM) is used to describe input-output relationship of HPA with linear dynamics. The predistorter is directly identified by complex power series model with memory, which is an approximate inverse of the HPA expressed by the WHM. The effectiveness of the proposed adaptive compensation scheme is validated by numerical simulation for 64QAM-OFDM systems.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2003.10a
• /
• pp.30-34
• /
• 2003

The coast area of our country has various tourist attraction factors of its own such as plenty of islands, uncontaminated waters and so on. Nevertheless, sea tourism and leisure facilities have not been developed enough since the national tourist/leisure policies have mainly been focused on the land tourism so far. Recently, the lake and sea areas are becoming more an more popular to people for spending their leisure times, and they, especially the young generations, are eagerly searching for some good ocean spots to enjoy the dynamics maritime sports. In this paper, we worked on the first design phase of environmentally and visually adaptive yacht, taking the cost effectiveness and the safety factors into account as well.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.2
• /
• pp.39-43
• /
• 2010

This paper presents an LMI-based method to design an adaptive sliding mode controller for a class of uncertain systems. In terms of LMIs an existence condition of a sliding surface is derived. And an adaptive switching feedback control law to guarantee the asymptotic stability as well as to estimate the norm bound of disturbances is proposed. Finally, a numerical design example for controlling a overhead crane model is given to show the effectiveness of the proposed method.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.4
• /
• pp.1780-1785
• /
• 2015

In this paper, the adaptive particle swarm optimization (APSO) algorithm is employed to design a gain-enhanced antenna with a reflector for energy harvesting. We placed the reflector below the main radiating element. Its back-radiated field is reflected and added to the forward radiated field, which could increase the antenna gain. We adopt the adaptive particle swarm optimization (APSO) algorithm, which improves the speed of convergence with a high frequency solver. The result shows that performance of the optimized design successfully satisfied the design goal of the frequency band, gain and axial ratio.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.1 no.1
• /
• pp.44-49
• /
• 2001

For minimum phase systems, the conventional fuzzy logic controllers (FLCs) use the error and the change-of-error as fuzzy input variables. Then the control rule table is a skew symmetric type, that is, it has UNLP (Upper Negative and Lower Positive) or UPLN property. This property allowed to design a single-input FLC (SFLC) that has many advantages. But its control parameters are not automatically adjusted to the situation of the controlled plant. That is, the adaptability is still deficient. We here design a single-input direct adaptive FLC (SDAFLC). In the AFLC, some parameters of the membership functions characterizing the linguistic terms of the fuzzy rules are adjusted by an adaptive law. The SDAFLC is designed by a stable error dynamics. We prove that its closed-loop system is globally stable in the sense that all signals involved are bounded and its tracking error converges to zero asymptotically. We perform computer simulations using a nonlinear plant and compare the control performance between the SFLC and the SDAFLC.

• Journal of Korean Society for Quality Management
• /
• v.36 no.1
• /
• pp.7-19
• /
• 2008

During the past two decades, a huge amount of research on adaptive control charts has been accomplished. Especially, variable sampling interval (VSI), variable sample size (VSS), and variable sample size and sampling interval (VSSI) charts have been focused by many researchers due to their simplicity and efficiency. On the other hand, the difference among notations, assumptions, methodologies may cause confusions in per forming further studies or practical implementations. This research analyses and compares diverse models so as to provide a unified view on statistical and economical characteristics. As a result, we perform comparative study on economical design models of VSI, VSS, and VSSI charts, respectively, We also present practical guidelines to utilize those adaptive control charts.

• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.1
• /
• pp.5-11
• /
• 2010

An adaptive formation control approach is proposed for nonhonolomic multiple mobile robots considering unknown slipping and skidding. It is assumed that unknown slipping and skidding effects are bounded by unknown constants. Under this assumption, the adaptive technique is employed to estimate the bounds of unknown slipping and skidding effects of each mobile robot. To deal with the skidding effect included in kinematics, the dynamic surface design approach is applied to design a local controller for each mobile robot. Using Lyapunov stability theorem, the adaptation laws for tuning bounds of slipping and skidding are induced and it is proved that all signals of the closed-loop system are bounded and the tracking errors and the synchronization errors of the path parameters converge to an adjustable neighborhood of the origin. Finally, simulation results are provided to verify the effectiveness of the proposed approach.