• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.514-522
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• 2014

A new type of high precision electromagnetic suspension (EMS) which can support heavy tray along long stroke rail is proposed in this paper. Compared with the conventional EMS, the suggested moving-core typed EMS has the levitation electromagnets (EMs) on the fixed rail. This scheme has high load capability caused by iron-core and enables simple tray structure. Also it does not have precision degradation caused by heat generation from EMs, which is a drawback of conventional EMS. With these merits, the proposed EMS can be an optimal contactless linear bearing in next generation flat panel display (FPD) manufacturing process if the ability of long stroke movement is proved. So a special Section Switching Algorithm (SSA) is derived from the resultant force and moment equations of the levitated tray which enables long stroke movement of the tray. In order to verify the feasibility of the suggested SSA, a simple test-setup of the EMS with 2 Section-changes is made up and servo-controlled in the simulation and experiment. The simulation shows the perfect changeover the EMs, and the experiment shows overall control performance of under ${\pm}40{\mu}m$ gap deviations. These results reveal that the newly suggested contactless linear bearing can simultaneously achieve high load capability and precision gap control as well as long stroke.

• 감성과학
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• 제24권3호
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• pp.81-90
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• 2021

본 연구에서는 전기 근육 자극(electrical muscle stimulation, EMS)에 사용되는 기존의 하이드로겔 패드의 단점인 사용 편의성, 쾌적성 등을 보완할 수 있는 e-textile (electronic textile)을 이용한 전기 근육 자극(electrical muscle stimulation, EMS) 패드인 EMSCT (electrical muscle stimulation conductive textile)를 연구를 하고자 하였다. SWCNT (Single-Walled Carbon Nanotube)와 H₂O의 농도 및 함침 공정 횟수를 변수로 하여, EMSCT는 5가지 직물(라디론, 네오프렌, 스판쿠션, 폴리100%, 베르가모)에 전도성을 부여하여 실험이 진행되었다. SWCNT (Single-Walled Carbon Nanotube)와 H₂O을 이용한 패딩 공정을 거쳤으며, 교류 측정 결과 하이드로겔과 가장 유사한 교류를 나타내는 것은 SWCNT:H₂O = 2:1의 베르가모 원단이라는 결과를 얻을 수 있었다. 또한, 편의성, 사용성, 심리적 만족성에 관한 사용성 평가를 통해 기존 하이드로겔 패드에 비해 EMSCT가 좋은 사용성을 가진다는 결과를 얻을 수 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.669-674
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• 1990

A nonlinear feedback linearizing control method for a EMS(Electro Magnetic Suspension) system is proposed. After linearizing the system using the exact linearizing method, conventional linear system control theory has been applied. Computer simulations are carried out in order to compare the performance of the proposed controller with that of the existing controller designed by using Taylor series expansion around nominal points.

• 전기학회논문지
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• 제62권9호
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• pp.1264-1269
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• 2013

In this paper, we study a disturbance observer (DOB) based controller for an EMS(Electro-Magnetic Suspension) system in presence of mass uncertainty and input disturbance. The DOB based controller is employed in order to compensate the modeling uncertainty and attenuate disturbance signals. For the design of DOB based controller, the Jacobain linearization of nonlinear system model equation is used. Computer simulation is carried out for nonlinear model in order to compare the performance of the proposed DOB controller with that of the conventional PID controller. The simulation results show that the substantial improvement in the performance can be achieved by the proposed DOB controller.

• 전기학회논문지
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• 제66권5호
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• pp.812-818
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• 2017

In this paper, we design a reduced-order disturbance observer (DOB) controller for an EMS (Electro-Magnetic Suspension) system with mass uncertainty. Compared with conventional DOB controller, the proposed reduced-order DOB controller can be implemented in a simpler way, since it uses reduced order nominal model and Q-filter. It is shown that the nominal model for the proposed DOB controller should be carefully chosen in order to achieve the robust stability in the present of mass uncertainty. Computer simulation results to validate the effectiveness of the proposed DOB controller are included.

• 한국통신학회논문지
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• 제33권12C호
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• pp.1075-1081
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• 2008

본 논문에서는 optical orthogonal code를 (OOC) 사용하는 optical 부호 분할 다중 접속 (code division multiple access: CDMA) 시스템에 알맞은 부호 획득 알고리즘을 제안한다. 일반적으로 부호 획득 알고리즘의 평균 부호 획득 시간이 (mean acquisition time: MAT) 짧을수록 알고리즘의 성능이 뛰어나다고 말할 수 있다 기존의 Multiple-shift (MS) 알고리즘은 부호 획득을 두 단계로 나누어 수행함으로써, serial-search (SS) 알고리즘에 비해 빠른 부호 획득이 가능하였다. 본 논문에서 제안한 enhanced multiple-shift (EMS) 알고리즘은 기존의 MS 알고리즘과는 달리 여러 개의 문턱값을 씀으로써 MS 알고리즘에 비해 더 짧은 MAT를 갖는다. 모의실험을 통해 제안한 EMS 알고리즘의 MAT 성능을 MS 알고리즘의 MAT 성능과 비교해 본 결과, 단일 사용자 환경 및 다중사용자 환경 모두에서 EMS 알고리즘이 MS 알고리즘에 비해 더 짧은 MAT를 갖는 것을 확인할 수 있었다.

• 한국화재소방학회논문지
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• 제27권5호
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• pp.15-18
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• 2013

본 연구는 자연 발생적인 화재 및 방화자에 의한 화재를 탐지하는 고효율 저비용의 옥외형 화재경보시스템으로 중소문화재, 천연기념물 및 옥외 시설물 등 화재 발생 시 관리 감시가 취약한 곳을 대상으로 한 소방시스템의 옥외 적용시 성능 및 시험에 대한 것이다. 재래적 화재감지시스템으로부터 탈피하여 지능적인 이동형 무인 화재감지시스템의 도입을 위해 화재경보시스템 성능시험, 기능시험, 옥외 환경시험, 불꽃시험 및 EMI/EMS 적합시험 등을 실시하였다. 성능시험, 기능시험, 불꽃시험 및 옥외방치시험을 3개월간 실시한바 양호하였고, 온도변화 성능시험도 $-30{\sim}70^{\circ}C$에서 양호하였으며 EMI/EMS 시험도 적합하였다. 불꽃검출거리는 75 m까지 증가되었고 대기모드 전원은 4시간 증가, 운영모드 전원에서의 동작시간은 3일까지 가능하였으며 센서뿐만 아니라 영상으로 상황을 인지하는데 적합함을 확인하였다.

• 전기학회논문지
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• 제60권8호
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• pp.1572-1576
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• 2011

The electromagnetic levitation(EMS) system is one of the well-known nonlinear system because of its nonlinearity and several control techniques have been proposed. We propose an ${\epsilon}$-scaling partial feedback controller for the ball position control of the EMS system. The key feature of our proposed controller is the use of the scaling factor ${\epsilon}$ which provides a function of controller gain tuning along with robustness. In this paper, we show the stability analysis of our proposed controller and the convergence analysis of the state observer in terms of ${\epsilon}$-scaling factor. In addition, the experimental results show the validity of the proposed controller and improved control performance over the conventional PID controller.

• Journal of electromagnetic engineering and science
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• 제4권2호
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• pp.51-55
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• 2004

With the progress of the electronics industry and radio communication technology, certain problems, such as electromagnetic interference(EMI), have arisen due to the increased use of electromagnetic(EM) waves. International organizations such as CISPR, FCC, and ANSI have provided the standards for the EM wave environment and for the countermeasure of the electromagnetic compatibility(EMC). EM wave absorbers are used for constructing an anechoic chamber to test and measure EMI and electromagnetic susceptibility(EMS). In this paper, we have designed an one-body EM(electromagnetic) wave ferrite absorber, based on the equivalent material constants method for both normally and obliquely incident waves, whose absorption abilities are superior to that of the conventional ones. The fabricated absorber has a thickness of 27.68 mm and shows an absorption ability over 20 ㏈ in the frequency from 30 MHz to 6 ㎓.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1334-1336
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• 2004

The existing problems of the Electro-Magnetic Suspension system such as air-gap disturbance, mass variation and actuator/sensor failure are described in amore specific manner. These problem can not be solved by conventional state-feedback and output-feedback control. Extended Kalman Filter is to linearize about a trajectory that is continually updated with the state estimates resulting from the measurements. In this paper, first, the physical properties of the EMS system are described. second, Extended Kalman Filer designed as form appliable EMS system. It is shown that state estimation performance can be obtained with the use of Extended Kalman filter, and that results from simulation, stability analyze.