• Earthquakes and Structures
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• v.11 no.6
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• pp.1101-1121
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• 2016

Base isolation, one of the popular seismic protection approaches proven to be effective in practical applications, has been widely applied worldwide during the past few decades. As the techniques mature, it has been recognised that, the biggest issue faced in base isolation technique is the challenge of great base displacement demand, which leads to the potential of overturning of the structure, instability and permanent damage of the isolators. Meanwhile, drain, ventilation and regular maintenance at the base isolation level are quite difficult and rather time- and fund- consuming, especially in the highly populated areas. To address these challenges, a number of efforts have been dedicated to propose new isolation systems, including segmental building, additional storey isolation (ASI) and mid-storey isolation system, etc. However, such techniques have their own flaws, among which whipping effect is the most obvious one. Moreover, due to their inherent passive nature, all these techniques, including traditional base isolation system, show incapability to cope with the unpredictable and diverse nature of earthquakes. The solution for the aforementioned challenge is to develop an innovative vibration isolation system to realise variable structural stiffness to maximise the adaptability and controllability of the system. Recently, advances on the development of an adaptive magneto-rheological elastomer (MRE) vibration isolator has enlightened the development of adaptive base isolation systems due to its ability to alter stiffness by changing applied electrical current. In this study, an innovative semi-active storey isolation system inserting such novel MRE isolators between each floor is proposed. The stiffness of each level in the proposed isolation system can thus be changed according to characteristics of the MRE isolators. Non-dominated sorting genetic algorithm type II (NSGA-II) with dynamic crowding distance (DCD) is utilised for the optimisation of the parameters at isolation level in the system. Extensive comparative simulation studies have been conducted using 5-storey benchmark model to evaluate the performance of the proposed isolation system under different earthquake excitations. Simulation results compare the seismic responses of bare building, building with passive controlled MRE base isolation system, building with passive-controlled MRE storey isolation system and building with optimised storey isolation system.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.51-57
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• 2014

In this paper, we introduce the adaptive threshold detection scheme based on an evolutionary arithmetic algorithm for the M-ary holographic data storage(HDS) system. The genetic algorithm is a particular class of evolutionary arithmetic based on the process of biological evolution, which is a very promising technique for optimization problem and estimation applications. In this study, to improve the detection performance that is degraded by the HDS channel environment and the pixel misalignment, the threshold value was assumed to be a population set of the evolutionary algorithm. The proposed method can find an appropriate population set of bit threshold, which minimizes bit error rate(BER) as increased generation. For performance evaluation, we consider severe misalignment effect in the 4-ary holographic data storage system. Furthermore, we measure the BER performance and compare the proposed methods with the conventional threshold detection scheme, which verifies the superiority of the proposed scheme.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.4
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• pp.51-61
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• 2004

In the dental field, the 3D tooth model in which each tooth can be manipulated individually is an essential component for the simulation of orthodontic surgery and treatment. To reconstruct such a tooth model from CT slices, we need to define the accurate boundary of each tooth from CT slices. However, the global threshold method, which is commonly used in most existing 3D reconstruction systems, is not effective for the tooth segmentation in the CT image. In tooth CT slices, some teeth touch with other teeth and some are located inside of alveolar bone whose intensity is similar to that of teeth. In this paper, we propose an image segmentation algorithm based on B-spline curve fitting to produce smooth tooth regions from such CT slices. The proposed algorithm prevents the malfitting problem of the B-spline algorithm by providing accurate initial tooth boundary for the fitting process. This paper proposes an optimal threshold scheme using the intensity and shape information passed by previous slice for the initial boundary generation and an efficient B-spline fitting method based on genetic algorithm. The test result shows that the proposed method detects contour of the individual tooth successfully and can produce a smooth and accurate 3D tooth model for the simulation of orthodontic surgery and treatment.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1181-1185
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• 2009

Adaptive Nuero-Fuzzy Inference System(ANFIS) 모형은 인공신경망과 퍼지모형의 특징을 가지는 모형으로 자료간의 관계가 선형이 아닌 비선형관계를 가질 경우 매우 정확한 예측 모형을 구축할 수 있는 특징이 있다. 월강수량 예측이 관측된 기상자료들과 비선형 관계에 있다고 생각되어 ANFIS 모형을 이용하여 월강수량을 예측하였다. 본 연구의 대상 지점으로는 금강유역의 대전 지점으로 선정하였다. 금강유역은 우리나라의 한가운데 위치하여 평균적인 강수형태 및 특징을 보여 좋은 실험유역으로 생각되어 선정하였다. 금강유역의 기상청에서 운영하는 지상 유인관측소 중 비교적 금강유역을 대표하고 양질의 자료가 기록되어 있다고 판단되는 대전지점을 실험지점으로 생각되어 선정하였다. 기상청 대전 유인 관측소에는 총 39년치 기상 자료가 기록되어 있다. 기상청에서는 전국 주요 도시들을 대상으로 2003년부터 월간 예보를 하고 있다. 본 연구에서는 기상청 월간예보와 기상청 대전 유인관측소에서 관측된 5년 치 기상자료를 모델의 입력자료로 구성하였다. 적절한 입력변수 조합을 구성하기 위하여 반복해법을 적용하였다. 5년 치 자료 중 절반은 학습을 시키는데 사용하였고 나머지 절반을 이용하여 모형을 검증하였다. 여러 입력변수를 이용하여 모형의 학습시킨 결과 입력변수가 3개 일 경우 가장 높은 정확도를 보였다. 입력변수가 3개로 학습 시킨 ANFIS 모형과 기상청에서 제공하는 월간예보를 비교해본 결과 ANFIS 모형을 적용하여 월 강수량을 예측하는 것이 기상청에서 제공하는 월간예보보다 높은 정확도를 보이는 것을 확인할 수 있었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.909-914
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• 2006

Vibration isolation tables are mostly required in precise measurement and manufacturing system. Among the vibration isolation tables, an air spring is the most favorable equipment because of low resonant frequency and high damping ratio. However, it is difficult to design the air spring with the required stiffness and damping ratio. Futhermore, whenever conventional active control methods are applied to the air spring, it may be difficult to obtain effective control performance due to high nonlinearity of air spring. In this paper, the optimal design of the air spring is performed using genetic algorithm to bring out low resonant frequency and high damping ratio. Also, active control of the vibration isolation table with 3-DOF model is proposed using the adaptive control method. Through experiments, optimal design is shown to be effective. And performance of the proposed control method is verified to be better than those of the passive control method and the conventional active control methods.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.804-811
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• 2015

The presence of responsive loads in the promising active distribution networks (ADNs) would definitely affect the power system problems such as distributed generations (DGs) studies. Hence, an optimal procedure is proposed herein which takes into account the simultaneous placement of DGs and smart meters (SMs) in ADNs. SMs are taken into consideration for the sake of successful implementing of demand response programs (DRPs) such as direct load control (DLC) with end-side consumers. Seeking to power loss minimization, the optimization procedure is tackled with genetic algorithm (GA) and tested thoroughly on 69-bus distribution test system. Different scenarios including variations in the number of DG units, adaptive power factor (APF) mode for DGs to support reactive power, and individual or simultaneous placing of DGs and SMs have been established and interrogated in depth. The obtained results certify the considerable effect of DRPs and APF mode in determining the optimal size and site of DGs to be connected in ADN resulting to the lowest value of power losses as well.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.102-108
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• 1999

The sliding rmde controller(SMC) is known as having the robust variable structures for the nonlinear control systems such as coupled tank system with the pararretric perturbations and with the rapid disturbances. But the adaptive tuning algorit1uns for their pararreters are not satisfactory. Therefore, in this paper, a Real Variable Elitist Genetic Algorithm based Sliding Mode Controller (RVEGA SMC) for the precise control of the coupled tank level was tried. The SMC's switching pararreters were optimized easily and rapidly by RVEGA The simulation results showed that the tank level could be satisfactorily controlled without any overshoot and any steady-state error by the proposed RVEGA SMC.GA SMC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1238-1259
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• 2019

Saving energy is a big challenge for Wireless Sensor Networks (WSNs), which becomes even more critical in large-scale WSNs. Most energy waste is communication related, such as collision, overhearing and idle listening, so the schedule-based access which can avoid these wastes is preferred for WSNs. On the other hand, clustering technique is considered as the most promising solution for topology management in WSNs. Hence, providing interference-free clustering is vital for WSNs, especially for large-scale WSNs. However, schedule management in cluster-based networks is never a trivial work, since it requires inter-cluster cooperation. In this paper, we propose a clustering method, called Interference-Free Clustering Protocol (IFCP), to partition a WSN into interference-free clusters, making timeslot management much easier to achieve. Moreover, we model the clustering problem as a multi-objective optimization issue and use non-dominated sorting genetic algorithm II to solve it. Our proposal is finally compared with two adaptive clustering methods, HEED-CSMA and HEED-BMA, demonstrating that it achieves the good performance in terms of delay, packet delivery ratio, and energy consumption.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.23-30
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• 2022

The active phased array antenna system performs beam steering, multi-beam formation and adaptive beam forming by controlling the amplitude and phase of signals fed to each radiating element. In order to obtain the desired radiation characteristics using an active phased array antenna system, the accurate amplitude and phase of the signal must be fed to each radiating element; however, due to various causes, the signal errors occurs in each radiating element. In this paper, a signal error estimation method of each radiating element is proposed. The proposed method simplifies the process of signal error estimation, and can quickly and accurately calculate the signal error.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.34-37
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• 2007

Face recognition is still a challenging problem in pattern recognition field which is affected by different factors such as facial expression, illumination, pose etc. The facial feature such as eyes, nose, and mouth constitute a complete face. Mouth feature of face is under the undesirable effect of facial expression as many factors contribute the low performance. We proposed a new approach for face recognition under facial expression applying two cascaded classifiers to improve recognition rate. All facial expression images are treated by general purpose classifier at first stage. All rejected images (applying threshold) are used for adaptation using GA for improvement in recognition rate. We apply Gabor Wavelet as a general classifier and Gabor wavelet with Genetic Algorithm for adaptation under expression variance to solve this issue. We have designed, implemented and demonstrated our proposed approach addressing this issue. FERET face image dataset have been chosen for training and testing and we have achieved a very good success.