• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.291-295
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• 2004

New valve driving system to control for the best volumetric efficiency at each load of an internal combustion engine within one engine cycle has been developed. The system needs to reduce pumping loss that cause by throttle valve during the intake valve is opened. In this system the intake valve is driven by a linear DC electromagnetic actuator which is controlled by personal computer. The result is compared both installed and uninstalled actuator into the cylinder head. By both of experimental and numerical calculation, the responsibility of the valve driving system to the engine speed was examined

• 한국전자파학회논문지
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• 제8권3호
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• pp.232-242
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• 1997

본 논문에서는 이동중인 물체의 인식거리 확대와 트랜스폰더의 저전력소비를 갖는 능동형 무선인식시스템을 설계하였다. 설계된 무선인식시스템의 송신주파수는 120 kHz, 응답주파수는 60 kHz로서 부반송파에 의한 ASK방식으로 쌍방향 전송방식을 채택하였다. 실험결과 9600 bps의 전송속도로 40 km의 이동속도를 갖는 물체에 대하여 무선인식 쌍방향 전송거리는 2 m를 나타내었으며 이때 응답기의 전류소비량은 15 ${mu}A$로서 우수한 저전력소모의 특성을 얻을 수 있었다.

• 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.

• 대한기계학회논문집
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• 제18권9호
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• pp.2312-2321
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• 1994

In this work the dynamics of an electromagnetic levitation system is described by a set of three first order nonlinear ordinary differential equations. The objective is to design a digital linear controller which takes the inherent instability of the uncontrolled system and the disturbing force into consideration. The controller is made by employing digital linear quadratic(LQ) design methodology and the unknown state variables are estimated by the kalman filter. The state estimation is performed using not only an air gap sensor but also both an air gap sensor and a piezoelectric accelerometer. The design scheme resulted in a digital linear controller having good stability and performance robustness in spite of various modelling errors. In case of using both a gap sensor and an accelerometer for the state estimation, the control input was rather stable than that in a system with gap sensor only and the controller dealt with the disturbing force more effectively.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.917-922
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• 2007

Electromagnetic suspension, the suspension system used for Maglev trains, is now being applied to urban and inter-city transportation systems, offering environmental benefits. This suspension system is actively controlled to stabilize the suspended vehicle as it runs over an elevated guideway, which, for various reasons, may have deviations in its height. For this reason, frequency responses of the suspension to height deviations must be predicted in the system design cycle. The equations of motion of the electromagnetic suspension employing the 5 state feedback control law are derived for frequency analysis. The results of this paper could be used to determine design requirements for the urban Maglev transportation system currently under development in Korea.

• Journal of electromagnetic engineering and science
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• 제14권4호
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• pp.336-341
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• 2014

Dosimetry of radiating electromagnetic wave from mobile devices to human body has been evaluated by measuring Specific Absorption Rate (SAR). Usual SAR measurement system scans the volume by robot arm to evaluate RF power absorption to human body from wireless devices. It is possible to fast estimate the volume SAR by software deleting robot moving time with the 2D surface SAR data acquired by arrayed probes. This paper shows the principle of fast SAR measurement and the measured data comparison between the fast SAR system and the robot scanning system. Data of the fast SAR is well corresponding with data of robot scanning SAR within ${\pm}3$ dB, and its dynamic range covers from 10 mW/kg to 30 W/kg with 4.8 mm probe diameter.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.48.4-48
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• 2001

Major objective of this paper is to develop the sliding mode control method for a nonlinear electro magnetic levitation system governed by a set of a second-order motion equation and a first-order electromagnetic equation. Simulations for initial responses were carried out to confirm the validity of the present design method.

• 한국자기학회지
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• 제26권2호
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• pp.55-61
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• 2016

본 논문에서는 설계변수 변화에 따른 특성을 빠른 시간 내에 파악할 수 있는 등가자기회로법(equivalent magnetic circuit method)을 활용하여 콜레노이드(colenoid) 타입의 선형 액츄에이터 설계 알고리즘을 제시하였다. 우선 선형 액츄에이터의 중요치수가 결정되면 등가자기회로법에 의해 슬롯 폭 비율 및 인가전류에 따른 클램핑력으로 파라미터 맵(parameter map)을 완성하고 이를 활용하여 효율적인 슬롯 폭 비율을 결정하였다. 또한 최대 클램핑력(clamping force)을 얻기 위해 극 폭 조절 알고리즘을 수행하여 최적의 극 폭 치수를 선정하였으며 이를 바탕으로 인가전류에 따른 클램핑력을 계산하여 40 kN 이상 출력하기 위한 최적의 극 수, 극 폭 치수 및 인가전류를 결정하였다. 제안된 설계 알고리즘은 최적설계 방법인 반응표면법(response surface method)과 비교하여 제안한 설계 알고리즘의 타당성을 검증하였다.

• 한국분말재료학회지
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• 제14권4호
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• pp.265-271
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• 2007

Electromagnetic wave absorbing materials have been developed to reduce electromagnetic interference (EMI) for electronic devices in recent years. In this study, Fe-Si-B-Nb-Cu base amorphous strip was pulverized using a jet mill and an attritor and heat-treated to get flake-shaped nanocrystalline powders, and then the powders were mixed, cast and dried with dielectric $Al_{2}O_{3}$ powders and binders. As a result, the addition of $Al_{2}O_{3}$ powders improved the absorbing properties of the sheets noticeably compared with those of the sheets without dielectric materials. The sheet mixed with 2 wt% $Al_{2}O_{3}$ powder showed the best electromagnetic wave absorption, which was caused by the increase of the permittivity and the electric resistance due to the dielectric materials finely dispersed on the Fe-based powder.

• 한국전자파학회지:전자파기술
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• 제4권3호
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• pp.45-53
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• 1993

재료의 전자파차폐효과는 일정한 송신전력에 대해 측정치구 내에 차폐재료가 놓여 있을 때와 없을 때에 수신 되는 수신전력의 차를 측정하므로써 결정된다. 구현된 전자파차폐효과 측정시스댐은 다양한 측정치구를 이용하고, 트랙킹신호원, 스펙트럼분석기, 스텝감쇠기, 고주파스위치, 신호증폭기 동을 사용하였으며, 퍼스날컴퓨터에 의해 측정이 자동으로 이루어지도록 설계되었다. 특히 고주파스위치와 쌍방향성결합기를 이용하여 한대의 스펙트럼분석기를 사용하여 입사전력, 반사전력, 투과전력을 측정할 수 있어 재료의 전자파차폐효과 측정은 물론, 차폐 특성에 관한 분석도 가능하여 재료의 설계에도 활용될 수 있다. 구현된 측정시스댐은 10 MHz~1 G GHz의 주파수대역에서 120 dB 이상의 동작영역을 가지며, 각종의 복합재료의 전자파차폐효과를 효과적으로 측정할 수 있다.