• Title/Summary/Keyword: genetic algorithm

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RVEGA SMC for Precise Level Control of Coupled Tank System (이중 탱크 시스템의 정밀 수위 제어를 위한 RVEGA SMC에 관한 연구)

  • 김태우;이준탁
    • 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.

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Methodology for Optimizing Permittivity Distribution of 145 kV Miniaturized Functional Graded Spacer Using Non-Dominated Sorting Genetic Algorithm-II (비지배 정렬 유전 알고리즘-II를 이용한 145 kV급 축소형 경사기능성 적용 스페이서의 유전율 분포 최적화 방법론)

  • Noh, Yo-Han;Kim, Seung-Hyun;Cheong, Jong-Hun;Cho, Han-Goo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.33 no.3
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    • pp.225-230
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    • 2020
  • Recently, with the miniaturization of GIS, there is a need for the miniaturization of spacers as accessories. Miniaturized spacers make it difficult to secure adequate insulation distances, resulting in a more concentrated electric field at the triple junction of high-voltage (HV) conductor-insulator (spacer)-insulation gas (SF6), which is a weakness in GIS. Therefore, by introducing a new concept design technology, functionally graded material (FGM), which is recently applied to various materials and parts industries, three-dimensional control of the dielectric constant distribution in a spacer can be expected to alleviate triple-junction electric field occupancy and improve insulation performance. In this study, we propose an optimized model using NSGA-II to optimize the permittivity distribution of FGM applied spacer.

Neural Network Modeling of Ion Energy Impact on Surface Roughness of SiN Thin Films (신경망을 이용한 SiN 박막 표면거칠기에의 이온에너지 영향 모델링)

  • Kim, Byung-Whan;Lee, Joo-Kong
    • Journal of the Korean institute of surface engineering
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    • v.43 no.3
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    • pp.159-164
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    • 2010
  • Surface roughness of deposited or etched film strongly depends on ion bombardment. Relationships between ion bombardment variables and surface roughness are too complicated to model analytically. To overcome this, an empirical neural network model was constructed and applied to a deposition process of silicon nitride (SiN) films. The films were deposited by using a pulsed plasma enhanced chemical vapor deposition system in $SiH_4$-$NH_4$ plasma. Radio frequency source power and duty ratio were varied in the range of 200-800 W and 40-100%. A total of 20 experiments were conducted. A non-invasive ion energy analyzer was used to collect ion energy distribution. The diagnostic variables examined include high (or) low ion energy and high (or low) ion energy flux. Mean surface roughness was measured by using atomic force microscopy. A neural network model relating the diagnostic variables to the surface roughness was constructed and its prediction performance was optimized by using a genetic algorithm. The optimized model yielded an improved performance of about 58% over statistical regression model. The model revealed very interesting features useful for optimization of surface roughness. This includes a reduction in surface roughness either by an increase in ion energy flux at lower ion energy or by an increase in higher ion energy at lower ion energy flux.

Ship Loading Plan for Tandem Crane in Container Terminals (탠덤 크레인을 고려한 컨테이너터미널 선적 계획)

  • Kwon, Sun-Cheol;Shin, Jae-Young;Kim, Sang-Jin
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2009.06a
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    • pp.167-168
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    • 2009
  • As the rapid increase of the container trade, most of the container terminals strive to improve the container handling productivity. Therefore, they consider to find efficient operating strategies and to introduce new container handling facilities. In terms of equipment, there are a variety of types of quay cranes. Single-lift crane operates only one container regardless of size and twin-lift crane operates two 20' containers or one 40' container simultaneously. Tandem crane, recently introduced, can operate four 20' containers or two 40' containers simultaneously. In this paper, we propose the mathematical model and the solution procedure of the ship loading scheduling problem for the tandem crane.

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Braking Torque Closed-Loop Control of Switched Reluctance Machines for Electric Vehicles

  • Cheng, He;Chen, Hao;Yang, Zhou;Huang, Weilong
    • Journal of Power Electronics
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    • v.15 no.2
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    • pp.469-478
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    • 2015
  • In order to promote the application of switched reluctance machines (SRM) in electric vehicles (EVs), the braking torque closed-loop control of a SRM is proposed. A hysteresis current regulator with the soft chopping mode is employed to reduce the switching frequency and switching loss. A torque estimator is designed to estimate the braking torque online and to achieve braking torque feedback. A feed-forward plus saturation compensation torque regulator is designed to decrease the dynamic response time and to improve the steady-state accuracy of the braking torque. The turn-on and turn-off angles are optimized by a genetic algorithm (GA) to reduce the braking torque ripple and to improve the braking energy feedback efficiency. Finally, a simulation model and an experimental platform are built. The simulation and experimental results demonstrate the correctness of the proposed control strategy.

Tracking System of Photovoltaic Generation Using DFC Controller (DFC 제어기를 이용한 태양광 발전의 추적시스템)

  • Jung, Byung-Jin;Choi, Jung-Sik;Ko, Jae-Sub;Kim, Do-Yeon;Jung, Dong-Hwa
    • Proceedings of the KIPE Conference
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    • 2008.10a
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    • pp.199-201
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    • 2008
  • In this paper proposed the solar tracking system to use direct fuzzy control order to increase an output of the PV (Photovoltaic) array. The solar tracking system operated two DC motors driving by signal of photo sensor. The control of dual axes is not an easy task due to nonlinear dynamics and unavailability of the parameters. Recently, artificial intelligent control of the fuzzy control, neural-network and genetic algorithm etc. have been studied. The fuzzy control made a nonlinear dynamics to well perform and had a robust and highly efficient characteristic about a parameter variable as well as a nonlinear characteristic. Hence the fuzzy control was used to perform the tracking system after comparing with error values of setting-up, nonlinear altitude and azimuth. In this paper designed a DFC(Direct Fuzzy Control)controller for improving output of PV array and evaluated comparison with efficient of conventional PI controller. The data which were obtained by experiment were able to show a validity of the proposed controller.

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A New Formulation for Coordination of Directional Overcurrent Relays in Interconnected Networks for Better Miscoordination Suppression

  • Yazdaninejadi, Amin;Jannati, Jamil;Farsadi, Murtaza
    • Transactions on Electrical and Electronic Materials
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    • v.18 no.3
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    • pp.169-175
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    • 2017
  • A safe and reliable protection system in distribution networks, specifically, those hosting distribution generation units, needs a robust over-current protection scheme. To avoid unintentional DG disconnection during fault conditions, a protection system should operate quickly and selectively. Therefore, to achieve this aim, satisfying coordination constraints are important for any protection scheme in distribution networks; these pose a challenging task in interconnected and large-scale networks. In this paper, a new coordination strategy, based on the same non-standard time-current curve for all relays, in order to find optimal coordination of directional over-current relays, is proposed. The main aim is to reduce violations, especially miscoordination between pair relays. Besides this, the overall time of operation of relays during primary and backup operations should be minimized concurrently. This work is being tackled based on genetic algorithms and motivated by the heuristic algorithm. For the numerical analysis, to show the superiority of this coordination strategy, the IEEE 30-bus test system, with a mesh structure and supplemented with distributed generation, is put under extensive simulations, and the obtained results are discussed in depth.

Study on the design and experimental verification of multilayer radiation shield against mixed neutrons and γ-rays

  • Hu, Guang;Hu, Huasi;Yang, Quanzhan;Yu, Bo;Sun, Weiqiang
    • Nuclear Engineering and Technology
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    • v.52 no.1
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    • pp.178-184
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    • 2020
  • The traditional methods for radiation shield design always only focus on either the structure or the components of the shields rather than both of them at the same time, which largely affects the shielding performance of the facilities, so in this paper, a novel method for designing the structure and components of shields simultaneously is put forward to enhance the shielding ability. The method is developed by using the genetic algorithm (GA) and the MCNP software. In the research, six types of shielding materials with different combinations of elements such as polyethylene (PE), lead (Pb) and Boron compounds are applied to the radiation shield design, and the performance of each material is analyzed and compared. Then two typical materials are selected based on the experiment result of the six samples, which are later verified by the Compact Accelerator Neutron Source (CANS) facility. By using this method, the optimal result can be reached rapidly, and since the design progress is semi-automatic for most procedures are completed by computer, the method saves time and improves accuracy.

Parameter Estimation of NSRPM using a Nelder-Mead Method (Nelder-Mead 기법을 이용한 NSRPM의 매개변수 추청 연구)

  • Cho, Hyun-Gon;Kim, Gwang-Seob;Yi, Jae-Eung
    • Proceedings of the Korea Water Resources Association Conference
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    • 2012.05a
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    • pp.710-710
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    • 2012
  • 구형펄스모형(Rectangular Pulse Model)에서 반영하지 못하는 강우의 군집특성을 잘 반영하는 NSRPM(Neyman-Scott Rectangular Pulse Model) 강우생성 모형은 수자원 분야에 널리 쓰이고 있다. 일반적으로 NSRPM의 5개의 매개변수를 추정하는 최적화기법으로 DFP(Davidon-Fletcher-Powell)과 유전자알고리즘(Genetic Algorithm)을 사용하고 있다. 그러나 DFP는 주어진 초기 값에 따라 민감하며 각 반복 단계마다 헤시안행렬(Hessian Matrix)을 계산하여야 하며 추정된 전체의 해가 국지해에 수렴 할 수 있는 단점이 있다. 유전자 알고리즘을 DFP와 다르게 헤시안 행렬을 사용하지 않고 최적화를 할 수 있다는 장점이 있으나 시간이 오래 걸리는 단점이 있다. 이에 본 연구에서는 이러한 단점을 보완, 강화 하기위해서 최적화 기법으로 반복 단계마다 미분계산이 필요하지 않고 빠른 속도로 계산이 가능한 Nelder-Mead 알고리즘 이용하여 NSRPM매개변수를 추정하고 정확도를 비교하였다. 표 1은 각 기법을 이용하여 추정된 매개변수를 이용하여 생성한 강우의 통계특성과 관측된 통계특성의 상대오차를 나타낸 것이다. 괄호 안 숫자는 중첩되지 않는 누적시간을 나타낸다. 상대오차는 다음과 같다(식 1). 분석결과 Nelder-Mead 기법이 1시간의 평균, 공분산과 6시간 분산 등 전체적으로 GA, DFP보다 높은 정확도를 보였다.

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Sampling Error Variation due to Rainfall Seasonality

  • Yoo, Chulsang
    • Proceedings of the Korea Water Resources Association Conference
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    • 2001.05a
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    • pp.7-14
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    • 2001
  • In this study, we characterized the variation of sampling errors using the Waymire-Gupta-rodriguez-Iturbe multi-dimensional rainfall model (WGR model). The parameters used for this study are those derived by Jung et al. (2000) for the Han River Basin using a genetic algorithm technique. The sampling error problems considering in this study are those far using raingauge network, satellite observation and also for both combined. The characterization of sampling errors was done for each month and also for the downstream plain area and the upstream mountain area, separately. As results of the study we conclude: (1) The pattern of sampling errors estimated are obviously different from the seasonal pattern of mentally rainfall amounts. This result may be understood from the fact that the sampling error is estimated not simply by considering the rainfall amounts, but by considering all the mechanisms controlling the rainfall propagation along with its generation and decay. As the major mechanism of moisture source to the Korean Peninsula is obviously different each month, it seems rather norma1 to provide different pattern of sampling errors from that of monthly rainfall amounts. (2) The sampling errors estimated for the upstream mountain area is about twice higher than those for the down stream plain area. It is believed to be because of the higher variability of rainfall in the upstream mountain area than in the down stream plain area.

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