• Title/Summary/Keyword: linear system

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Optimal Design of Air Compressor-Driving Quadratic Linear Actuator in Fuel Cell BOP System Using Orthogonal Arrays Matrix

  • Kim, Jae-Hee;Kim, Jin-Ho;Jang, Chang-Hwan
    • Journal of Magnetics
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    • v.16 no.2
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    • pp.120-124
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    • 2011
  • The design of an air compressor-driving quadratic linear actuator in a fuel cell BOP system is studied using orthogonal techniques. The approach utilizes an orthogonal array for design of 'experiments', i.e. the scheme for numerical simulations using a finite element method. Eco-friendly energy is increasingly important due to the depletion of fossil fuels and environmental pollution. Among the new energy sources, fuel cell is spotlighted as renewable energy because it produces few dusts. The air compressor performance is directly related to the efficiency of the fuel cell BOP system has high power consumption. In this paper, an optimized technique using an orthogonal matrix is applied to the design problem to improve the performance of quadratic linear actuator.

Research on the Image Encryption Method using a Linear-structure Chaos System (선형구조 혼돈계를 이용한 이미지 암호와 방법 연구)

  • Cho, Chang Ho;Yim, Geo Su
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.7 no.4
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    • pp.75-79
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    • 2011
  • With the rapid growth of digital communication and the internet, the importance of conducting research on data encryption methods is increasing. Some of the pertinent researches that have been conducted so far introduced data encryption methods using chaos systems, and numerous researches are currently being conducted on such methods. The signals produced by the chaos systems are called "determined noise," and if this is applied to data encryption, very effective results can be obtained. Using the Henon map, the relationship between the non-linearity of the chaos system and the strength of encryption was analyzed, and a linear-structure chaos system that uses non-linearity as a variable for encryption strength was constructed. Using the constructed chaos system, an image was encrypted and decoded, and the correlation coefficient of the linear-structure chaos system's performance was calculated and then analyzed.

Performance analysis of Binary Clipping PW-CDMA against non-linear distortion over Flat fading Channel (Flat 페이딩 채널환경에서 비선형 왜곡에 대한 Binary Clipping PW-CDMA 성능 분석)

  • 김현욱;안치훈;옥경준;정준엽;김동구
    • Proceedings of the IEEK Conference
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    • 2003.11c
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    • pp.297-301
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    • 2003
  • The binary clipping PW/CDMA system is considered. This system can be constructed with effective cost. leading to reduce the influence of the non-linear amplifier because of converting multi-level signals into constant envelope signals. In addition, the clipping method which is to clip out signal amplitude at some level when multi-level signals are converted into constant envelope signals is used. The multi-level signals are clipped at 1 and -1 to limit the extension of bandwidth and to maintain the bandwidth after clipping. In this paper, the performance of the binary clipping PW/CDMA system with the non-linear amplifier analyzed by simulation over AWGN and flat fading channels respectively. The binary clipping PW/CDMA system with the non-linear amplifier is 2.2dB and 0.9dB better than conventional DS/CDMA system over the flat fading channels when the number of users are 9 and 17 respectively.

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Analysis of the Dynamic charactristics of Linear Induction Motor considering the variation of loads (부하변동을 고려한 선형유도전동기의 동특성 분석)

  • Chun, Sam-Suk;Park, Chan-Won;Lim, Byung-Ok
    • Proceedings of the KIEE Conference
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    • 2005.07b
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    • pp.1162-1164
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    • 2005
  • A Linear Induction Motor that generates the direct thrust directly, is widely used for the operation system of electrified railroad, elevation system, conveyer system, and so on. There are two analysis methode of linear induction motor characteristics. One is the electrical magnetic analyzing, the other is analyzing equivalent circuit. The electrical magnetic analyzing methode has available advantages to consider the physical condition. The equivalent circuit analyzing methode has the elementary methode in the system of vector control and over shoot situation. In this paper, It is used the dynamic characteristic analyzing methode that can calculate efficiently the end effect by using equivalent circuit methode in the operating linear induction motor system modeling and doing simulation of output characteristics of vector controller.

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A Study on the Control of a Linear Motor System of the Universal Machining Center (복합가공기용 리니어 모터 시스템의 제어 연구)

  • Kong Kyoung-Chul;Jeon Do-Young
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.94-99
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    • 2005
  • Though the technology on the ultra-precise machining has been developed intensively, the high speed and high precision for large machining range is still very hard to achieve. The linear motor system fur the universal machining center is proper fur high speed and high precision, but it has drawback of sensitivity to disturbance. In this research, two degrees of freedom controller based on the zero phase error tracking controller (ZPETC) and disturbance observer are proposed to improve the tracking performance and dynamic stiffness of linear motor system. The proposed controller is verified in simulations and experiments on a nano-positioner system, and the experimental result shows that the tracking performance improved. In addition, the PID optimization method is proposed for the commercialized controller such as the PMAC based system. The tracking as well as impedance is included in the cost function of optimization.

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A Study on Membrane Fouling by Flux and Linear Velocity in Coagulation/Ultrafiltration Membrane System (응집·한외여과 조합공정에서 플럭스와 선속도가 막오염에 미치는 영향에 관한 연구)

  • Moon, Seong-Yong;Lee, Sang-Hyup;Kim, Seung-Hyun;Yoon, Cho-Hee
    • Journal of Korean Society of Water and Wastewater
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    • v.19 no.4
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    • pp.429-436
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    • 2005
  • A coagulation/ultrafiltration membrane hybrid system was operated to treat river water with capacity of $0.06m^3/d$. The impact on membrane fouling by flux and linear velocity was investigated. It is known that pressure increase is proportional to flux increase. However, pressure increase was much faster than theoretical value in the pilot plant test. So it was suggested that flux was on important factor in ultrafiltration of continuous operation. Membrane fouling was decreased when linear velocity was increased. This phenomenon was found more obviously without coagulation. With the combination of coagulation and sedimentation, membrane fouling was not reduced conspicuously. Big particles formed during coagulation and sedimentation were destroyed by feed and circulation pumping, which resulted in little effect on membrane fouling reduction. The degree of destruction was similar at various linear velocities. In this study, the hollow fiber membrane was used and the system was operated in pressure type module. In case of the system used in this study, membrane fouling has been affected lightly by linear velocity variation when coagulation pretreatment was applied.

A Solid State Controller for Self-Excited Induction Generator for Voltage Regulation, Harmonic Compensation and Load Balancing

  • Singh Bhim;Murthy S. S.;Gupta Sushma
    • Journal of Power Electronics
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    • v.5 no.2
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    • pp.109-119
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    • 2005
  • This paper deals with the performance analysis of static compensator (STATCOM) based voltage regulator for self­excited induction generators (SEIGs) supplying balanced/unbalanced and linear/ non-linear loads. In practice, most of the loads are linear. But the presence of non-linear loads in some applications injects harmonics into the generating system. Because an SEIG is a weak isolated system, these harmonics have a great effect on its performance. Additionally, SEIG's offer poor voltage regulation and require an adjustable reactive power source to maintain a constant terminal voltage under a varying load. A three-phase insulated gate bipolar transistor (IGBT) based current controlled voltage source inverter (CC- VSI) known as STATCOM is used for harmonic elimination. It also provides the required reactive power an SEIG needs to maintain a constant terminal voltage under varying loads. A dynamic model of an SEIG-STATCOM system with the ability to simulate varying loads has been developed using a stationary d-q axes reference frame. This enables us to predict the behavior of the system under transient conditions. The simulated results show that by using a STATCOM based voltage regulator the SEIG terminal voltage can be maintained constant and free from harmonics under linear/non linear and balanced/unbalanced loads.

Characteristic Analysis of a Linear Induction Motor for 200-km/h Maglev

  • Jeong, Jae-Hoon;Lim, Jae-Won;Park, Do-Young;Choi, Jang-Young;Jang, Seok-Myeong
    • International Journal of Railway
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    • v.8 no.1
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    • pp.15-20
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    • 2015
  • As a result of the current population concentrations in urban centers, demand for intercity transportation is increasing rapidly. Railway transportation is becoming popular as an intercity transportation because of its timely service, travel speeds and transport efficiency. Among the many railway systems, the innovative and environmentally friendly maglev system has been rated very highly as the next-generation intercity railway system. Linear induction motors are widely used for the propulsion of maglev trains because of their light weight and low construction costs. The urban maglev that was recently completed in Incheon airport site employs a 110km/h class linear induction motor. However, this system was designed to meet requirements for inner-city operations and is not suitable as an intercity transportation system, which requires medium to high speeds. Therefore, this study deals with the characteristics and designs of linear induction motors used for the propulsion of maglev trains that can be used as intercity trains. Rail car specifications for high-speed trains have been presented, and the characteristics of linear induction motors that can be used for the propulsion of these trains have been derived using the finite element method (FEM).

Adaptive Force Ripple Compensation and Precision Tracking Control of High Precision Linear Motor System (초정밀 선형 모터 시스템의 적응형 힘리플 보상과 정밀 트랙킹 제어)

  • Choi Young-Man;Gweon Dae-Gab;Lee Moon G.
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.12 s.177
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    • pp.51-60
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    • 2005
  • This paper describes a robust control scheme for high-speed and long stroke scanning motion of high precision linear motor system consisting of linear motor, air bearing guide and position measurement system using heterodyne interferometer. Nowadays, semiconductor process and inspection of wafer or LCD need high speed and long travel length for their high throughput and extremely small velocity fluctuations or tracking errors. In order to satisfy these conditions, linear motor system are widely used because they have large thrust force and do not need motion conversion mechanisms such as ball screw, rack & pinion or capstan with which the system are burdened. However linear motors have a problem called force ripple. Force ripple deteriorates the tracking performances and makes periodic position errors. So, force ripple must be compensated. To maximize the tracking performance of linear motor system, we propose the control scheme which is composed of a robust control method, Time Delay Controller (TDC) and a feedforward control method, Zero Phase Error Tracking Control (ZPETC) for accurate tracking a given trajectory and an adaptive force ripple compensation (AFC) algorithm fur estimating and compensating force ripple. The adaptive ripple compensation is continuously refined on the basis of tracking error. Computer simulation results based on modeled parameters verify the effectiveness of the proposed control scheme for high-speed, long stroke and high precision scanning motion and show that the proposed control scheme can achieve a sup error tracking performance in comparison to conventional TDC control.

Design of PM Excited Transverse Flux Linear Motor of Inner Mover Type

  • Kang Do-Hyun;Ahn Jong-Bo;Kim Ji-Won;Chang Jung-Hwan;Jung Soo-Jin
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.2
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    • pp.137-141
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    • 2005
  • A transverse flux, PM-exited linear motor (TFM-LM) with inner mover was designed and built. Its output power density is higher and its weight is lower than those of the conventional PM exited linear synchronous motors (PM LSM). To obtain the maximum thrust force under the given volume, the thrust force density with respect to the ratio of the slot width and the length of pole pitch is analyzed by the 3-dimension finite element method (FEM). Finally, calculated static thrust forces was compared with the experimental values. The calculated and measured performance of the transverse flux, PM-exited linear motor with inner mover revealed great potential for system improvements by reducing the mass of the linear motor. For examples, when this motor was applied to a ropeless elevator, it was possible to increase the power density by more than 400% over the conventional PM-LSM. The results of this study recommend this type of motor for the ropeless elevator or gearless direct linear driving system.