• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.7
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• pp.339-345
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• 2000

This paper deals with the displacement estimation of magnetically suspended simple 1 DOF(degree of freedom) system without the displacement sensor. Inherently electro-magnet for control has two natural feedback loops. One is the transfer function which represents the dependance of the amount of the magnetic flux on the gap displace-ments. The other is the transfer function expressing the properties that the back electromotive force is derived from the time derivative of the magnetic flux. Through these two feedback loops, information about the gap length can be represented by the magnetic flux and the coil current. This means that the gap length can be detected from these two states variables of the electromagnet without a displacements sensor(self-sensing). The displacement can be estimated with the magnetic flux subtracted by the coil current. In this paper we use a balance beam in order to deal with the displacement sensorless estimation of the magnetic bearing system. For the stable estimation of the gap displacements by using the method of self-sensing simple PD controller is used. We first show the mathematical model of the balance beam, and then we show the effectiveness of the current and flux feedback for making stable estimation of the gap displacements for the balance beam. Simulation results show the effectiveness of the current and flux feedback for good estimation of the displacement without using displacement sensor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.888-893
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• 2004

This paper proposed a dual actuator using bimorph PZT for information storage device based on prove array NSOM(Near-field Scanning Optical Microscopy). The gap between the media and the optical head should be maintained within the optical tolerance. Therefore, a new actuator having high sensitivity is required. Bimorph PZT, which has fast access time and high sensitivity characteristic, is suitable for this precise actuating system. This paper is focused on derivation of mathematical model of dual bimorph PZT actuator and control algorithm. Hamilton's principle was used for mathematical model. The model is verified by FEA(Finite Element Analysis), and compared with experimental results. Different control algorithms were used f3r two bimorph PZT actuating same direction and opposite direction. The gap between recording media and optical head was controlled within 20nm in experiment.

• Journal of Welding and Joining
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• v.14 no.4
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• pp.79-88
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• 1996

For improvement in productivity and weld quality, weld seam tracking and welding parameter control are very essential in the welding of a structure which can not be cxactly fit-up due to mismatch, discontinous gap, deflection, etc.. In this study, an automatic weld seam tracking system is developed for I-butt joint structure, and the system consists of XYZ working table, vision sensor and user interface program. In the developed vision sensor system, an image projection algorithm for weld-line detection and an adaptive current control algorithm for gap variation were implemented. The user interface program developed in this study by basing on the objct oriented concept could provide very convenient way to utilize the tracking system with the pull-down menu driven structure. The developed system showed a good seam tracking and weld quality control capability corresponding to deflected weld lines and gap variations.

• Journal of the Semiconductor & Display Technology
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• v.23 no.1
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• pp.104-109
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• 2024

In this paper, we propose structures of a socket that can improve signal transmission characteristics compared to the existing silicone rubber socket. A coaxial rubber socket was proposed to improve signal distortion due to electromagnetic interference between signal lines. And an air gap rubber socket was proposed to improve the degradation of reflection characteristics due to high dielectric constant. Using a 3D electromagnetic field simulator, the S-parameter and crosstalk of the three sockets were compared and the signal transmission characteristics were analyzed. In both coaxial rubber socket and the air gap rubber socket, S-parameter and crosstalk were improved compared to the silicone rubber socket. Among them, the air gap rubber socket was the best for S-parameter, and the coaxial rubber socket was the best for crosstalk.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.596-599
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• 2000

벡터 제어이론은 교류전동기의 토오크와 자속을 독립적으로 제어할 수 있는 특징이 있으므로 토오크 제어를 주로 하는 견인용 전동기의 제어에 적용하기 위한 연구가 활발히 수행되어 왔다 그러나 선형 유도전동기 구동에는 아직 널리 사용되지 않은 실정이다 벡터 제어이론은 일반적으로 회전자자속 기준제어(Rotor flux oriented control)을 의미하며 이를 구현하기 위한 방법은 자속을 직접 측정 혹은 연산하는 직접제어 방식과 속도를 측정하여 슬립주파수 명령을 제어하는 간접방식으로 분류된다. 최근에는 기존의 회전자자속 기준방식뿐만 아니라 고정자자속(Stator flux oriented) 공극자속(Air gap flux oriented) 기준 방식등이 제안되고 있다. 본연구에서는 자기부상열차의 추진용 선형 유도 전동기의 추진에 가장 적합하다고 생각되는 고정자자속 기준벡터제어 방식과 이를 구현하기 위한 고정자 자속을 추정하는 방법에 대하여 설명한다. 또한 속도제어를 위한 속도 추정방식도 안내코일 등 부장치 없이 전동기 파라미터로 추정할 수 있는 기법에 대하여 논한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.453-458
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• 2011

Air preheater uses the waste heat of the gas which burnt from the boiler from the thermal power plant. Air preheater it is established in the exit of the boiler follows in change of temperature combustion gas and the vibration which it follows in thermal expansion and contraction occurs. Air preheater with ruse the gas the seal the place where it includes a gap in the structure which it does, the vibration which it follows in change of temperature fluctuates the displacement of gap, fluctuation of the leakage quantity which occurs from gap there is a possibility of decreasing an effect to system. Part system it will be able to control the interval of gap in order, control mechanism about under establishing the place where it does the gap control actively, measures a gap the displacement sensor for is necessary. Like this displacement sensor the condition must do continuous running from atmosphere of high temperature was demanded all. This paper investigates the implementation instance of hazard existing which implement the high temperature displacement sensor, it analyzes, produces the result which it examines a model, it was a presentation. These results with the fact that it will contribute in the research for the implementation and a localization of the high temperature displacement sensor and advanced air preheater.

• Journal of Welding and Joining
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• v.29 no.6
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• pp.77-81
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• 2011

In most industry, manual GTAW welding is preferred for formation of stable back bead in root weld of butt joint. However, manual GTAW welding has low productivity as compared with GMAW, also it has unstable bead quality which depend on skilled workers. So it is necessary to develop process of root pass welding by using automation GMAW that have stable back bead formation and high productivity. In this paper, the design of U-groove with 3mm root face was applied to extend the tolerance of misalignment in condition of standard root gap 1.5mm. Consequently, for the formation of stable back bead in root pass of butt welding, in case of the narrow root gap(0.5mm) the large arc force was applied by increasing the current and voltage. In case of the large root gap(2.5mm), the small arc force was applied by decreasing the current and voltage. Considering the various root gap, the required deposited metal was controlled by welding speed only.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.12-19
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• 2005

This paper proposed a dual actuator using Bimorph PZT for information storage device based on prove array NSOM(near-field scanning optical microscopy). The gap between the media and the optical head should be maintained within the optical tolerance. Therefore, a new actuator having high sensitivity is required. Bimorph PZT, which has fast access time and high sensitivity characteristic, is suitable for this precise actuating system. This paper is focused on derivation of mathematical model of dual Bimorph PZT actuator and control algorithm. Hamilton's principle was used for mathematical model. The model is verified by FEA(finite element analysis), and compared with experimental results. Different control algorithms were used for two Bimorph PZT actuating same direction and opposite direction. The gap between recording media and optical head was controlled within 20nm in experiment.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.747-753
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• 1992

The modeling and control design schemes are developed for maglev systems with a combined lift and guidance. First, bond graph techniques are applied for modeling these multi-energy domain systems more logically and systematically. And the stability loop via pole placement and the performance loop via loop-shaping LQ control are designed. The suggested controller satisfies the required characteristics of stability and performance simultaneously. Finally, the robustness of the synthesized maglev control system is evaluated for the variations of air gap and vehicle mass through computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.316-316
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• 2000

SPM dynamic model was developed by using Bland & Ford formulas considered elastic zone in roll gap, gauge meter equation, tension equation, speed equation and actuator models. And SPM controllers of the field were done model ing. It was shown the efficiency of constant tension, rol1ing force and elongation controllers by the simulation program and it was recommended the proper gain to the controllers of the field.