• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.2
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• pp.98-106
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• 2006

This paper proposes to position and speed control of interior Permanent magnet synchronous motor(IPMSM) drive without mechanical sensor. Also, this paper develops a adaptive fuzzy controller based fuzzy logic control for high performance of PMSM drives. In the proposed system, fuzzy control is used to implement the direct controller as well as the adaptation mechanism. A Gopinath observer is used for the mechanical state estimation of the motor. The observer was developed based on nonlinear model of IPMSM, that employs a d-q rotating reference frame attached to the rotor. A Gopinath observer is implemented to compute the speed and position feedback signal. The validity of the proposed scheme is confirmed by various response characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.9
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• pp.2341-2348
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• 1996

This paper proposes an image compression algorithm that adopts projection scheme on mean-residual metod. Sub-blocks of an image are encoded using mean-residual method where mean value is predicted according to that of neighboring blocks. Projection scheme with 8 directions is applied to the compression of residual signals of blocks. Projection vectors are finite-state vector quantized according to the projection angle of nighboring blocks in order to exploit the correlation among them. Side information to represent the repetition of projection is run-length coded while the information for projection direction is compressed using entropy encoding. The proposed scheme apears to be better in PSNR performance when compared with conventional projection scheme as well as in subjective quality preserving the edges of images better than most tranform methods which usually require heavy computation load.

• Structural Engineering and Mechanics
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• v.40 no.1
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• pp.49-64
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• 2011

An analytical method is presented to investigate electromagnetothermoelastic behaviors of a hollow sphere composed of functionally graded piezoelectric material (FGPM), placed in a uniform magnetic field, subjected to electric, thermal and mechanical loads. For the case that material properties obey an identical power law in the radial direction of the FGPM hollow sphere, exact solutions for electric displacement, stresses, electric potential and perturbation of magnetic field vector in the FGPM hollow sphere are determined by using the infinitesimal theory of electromagnetothermoelasticity. Some useful discussion and numerical examples are presented to show the significant influence of material inhomogeneity. The aim of this research is to understand the effect of composition on electromagnetothermoelastic stresses and to design optimum FGPM hollow spheres.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.3
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• pp.190-196
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• 1999

Continuation power flow has been developed to remove the ill-condition problem caused by singularity of power flow Jacobian at and near at steady-state voltage instability point in conventional power flow. Continuation power flow consists of predictor and corrector. In prddictor, the direction vector at the resent solution is caluculated and the initial guess of next solution is determined at the distance of step length. The selection of step length is a very important part, since computational speed and convergence performance are both greatly affected by the choice of the step length. This paper presents the practical step length selection algorithm using the reactive power generation sensitivith. In numulation, the proposed algorithm is compared with step length selection algorithm using TVI(tangent vector index).

• The Transactions of the Korea Information Processing Society
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• v.7 no.3
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• pp.1013-1020
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• 2000

In this paper, we propose an algorithm which segments hierarchically blocks of image using discrete cosine transform(DCT) and execute finite-state vector quantization (FSVQ) for each block. Using DCT coefficient feature, image is segmented hierarchically to large smooth block and small edge block, then the block hierarchy informations are transmitted. The codebooks are respectively constructed for each hierarchical blocks, the encoder transmits codeword index using FSVQ for reducing encoded bit with hierarchical segmentation. Compared with side match VQ(SMVQ) and hierarchical FSVQ(HFSVQ) algorithm, about Zelda and Boat image, the new algorithm shows better picture quality with 1.97dB and 2.85 dB difference as to SMVQ, 1.78dB and 1.85dB diffences as to HFSVQ respectively.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.367-369
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• 2001

GSPA(Generic Shortest Path Algorithm)은 각종 정보통신 네트워크 상에서 멀티미디어 정보전송시 요구되는 QoS 기반의 라우팅을 위한 새로운 라우팅 알고리즘이다. 전체적인 동작은 원시노드(Source Node)에서 목적노드(Destination Node) 사이에서 이전 단계의 재귀호출에서 찾은 최단 경로를 기준으로 해서 이웃 노드들을 대상으로 재귀호출을 통해서 QoS 요구조건을 만족하는 경로정보를 기록하면서 최단 경로를 찾는 알고리즘이다. GSPA는 기존 Distance Vector 알고리즘이 경로를 설정하기 위해 많은 시간과 대역폭을 낭비하며 네트워크 형상이 수시로 변경될 때 “Counting to Infinity”현상을 발생시키는 단점을 보완하고, Link-State 데이터 베이스를 이용해서 함수 재귀호츨을 통해서 최단 경로를 찾아냄으로써 구현하기가 쉬운 알고리즘이다. 또, Distance-Vector와 Link-State 알고리즘의 장점을 수용하였으며, 이 알고리즘을 분산 네트워크 환경에서 동작하도록 수정하면 분산 네트워크 환경에서의 Hierarchical Routing, Multi-Path Routing, QoS Routing을 위한 기본 알고리즘으로 매우 좋은 특성들을 가지고 있다. 본 논문에서는 이 알고리즘을 소개하고 간단한 예를 통해 기본 동작에 대해 살펴본다.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.353-356
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• 1995

This paper proposes a simple identification method of the rotor time constant to solve the degradation of motor performance due to the difference between the rotor time constant of a controller and actual one in slip frequency type vector control scheme. The proposed method is based on rotor induced voltage equations and it is confirmed that immunity of the stator resistance thermal variation. The simulation results show that the proposed method suitably identifies the rotor time constant in steady state as well as in transient state.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.339-342
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• 2012

Nowadays, Spoken Dialogue System is rapidly growing by investing a lot from researches as well as organizations. One of concrete evidences is that the appearance of commercial systems such as Siri, SVoice, DARPA, CLASSiC, GSearch etc. Moreover, Spoken Dialogue System is widely believed to be the future direction of software development. In Spoken Dialogue System, users interact to software by using their own voice instead of use their hands, keyboard, and mouse. This paper continuously presents our development of the Spoken Dialogue System on News. Particularly, we propose detailed design such as semantic concepts, semantic frames, slots, and so on for applying Hidden Vector State Model into our Spoken Dialogue System for Spoken Language Understanding.

• Earthquakes and Structures
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• v.16 no.6
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• pp.679-690
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• 2019

This paper presents machine learning methods using Support Vector Machine (SVM) and Multilayer Perceptron (MLP) to analyze optimal damper distribution for structural vibration control. Regarding different building structures, a genetic algorithm based optimization method is used to determine optimal damper distributions that are further used as training samples. The structural features, the objective function, the number of dampers, etc. are used as input features, and the distribution of dampers is taken as an output result. In the case of a few number of damper distributions, multi-class prediction can be performed using SVM and MLP respectively. Moreover, MLP can be used for regression prediction in the case where the distribution scheme is uncountable. After suitable post-processing, good results can be obtained. Numerical results show that the proposed method can obtain the optimized damper distributions for different structures under different objective functions, which achieves better control effect than the traditional uniform distribution and greatly improves the optimization efficiency.

• International Journal of Computer Science & Network Security
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• v.21 no.1
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• pp.207-213
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• 2021

Networks in Mobile ad hoc contain distribution and do not have a predefined structure which practically means that network modes can play the role of being clients or servers. The routing protocols used in mobile Ad-hoc networks (MANETs) are characterized by limited bandwidth, mobility, limited power supply, and routing protocols. Hybrid routing protocols solve the delay problem of reactive routing protocols and the routing overhead of proactive routing protocols. The Ant Colony Optimization (ACO) algorithm is used to solve other real-life problems such as the travelling salesman problem, capacity planning, and the vehicle routing challenge. Bio-inspired methods have probed lethal in helping to solve the problem domains in these networks. Hybrid routing protocols combine the distance vector routing protocol (DVRP) and the link-state routing protocol (LSRP) to solve the routing problem.