• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.561-562
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• 2008

• 한국의학물리학회지:의학물리
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• 제25권4호
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• pp.248-254
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• 2014

본 연구에서는 미국 Xoft 사에서 근접치료 장치(elecronic brachytherapy)를 목적으로 개발된 소형 X-선 튜브를 치과용 영상장비로 사용함에 있어서 고전압 발생장치의 제어용 장치를 개발하고 영상용 제어 방식으로 최적화하고자 한다. 연구에서 사용된 X-선 튜브와 고전압 발생 장치는 각각 Axxent S700과 XF060NZZ485를 사용하였고, AT90CAN128 MCU를 사용하여 제어보드를 제작하였다. 관전압을 50 kV로 고정한 후에 제어 방식에 따라서 필라멘트 전류 제어 방식과 관전류제어 방식으로 나누었다. 필라멘트 제어 방식은 다시 필라멘트 가열 시간에 따라서 5초와 10초의 두 가지로 나누어 실험하였다. 필라멘트 전류 제어 방식에서는 필라멘트 예열 시간이 10초 이상이 되지 않으면 설정된 관전류 값에 도달하기 어려웠고, 관전류가 발생하는 필라멘트 전류도 1,300~1,350 mA로 가변적이었으며, 관전류가 발생된 이후에도 설정된 목표 값에 도달하기 위해서는 약 5초 이상의 시간이 소요되었다. 하지만 관전류 제어 방식에서는 관전류가 설정된 목표 값에 시간 지연 없이 즉각적으로 도달하였으며 그 때의 필라멘트 전류 값은 1,500 mA였다. 본 연구에서는 소형의 X-선 튜브에 고전압을 안정적으로 공급하는 제어 장치를 개발하였고, 방사선 영상장비로 사용함에 있어서는 관전류 제어 방식이 적합함을 보였다.

• Interaction and multiscale mechanics
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• 제3권3호
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• pp.257-266
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• 2010

A novel resonance based proximity DC current sensor is proposed. The sensor consists of a piezo sensed and actuated cantilever beam with a permanent magnet mounted at its free end. When the sensor is placed in proximity to a wire carrying DC current, resonant frequency of the beam changes with change in current. This change in resonant frequency is used to determine the current through the wire. The structure is simulated in micro and meso scale using COMSOL Multi physics software and the sensor is found to be linear with good sensitivity.

• 한국레이저가공학회지
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• 제12권2호
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• pp.26-30
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• 2009

Scanning Electron Microscopy (SEM) includes high voltage generator, electron gun, column, secondary electron detector, scan coil system and image grabber. Column includes electron lenses (condenser lens and objective lens). Condenser lens generates fringe field, makes focal length and control spot size. Focal length represents property of lens. Objective lens control focus. Most of the electrons emitted from the filament, are captured by the anode. The portion of the electron current that leaves the gun through the hole in the anode is called the beam current. Electron beam probe is called the focused beam on the specimen. Because of the lens and aperture, the probe current becomes smaller than the beam current. It generate various signals(backscattered electron, secondary electron) in an interaction with the specimen atoms. In this paper, we describe the result of research to develop the core elements for low-resolution SEM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2249-2251
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• 1997

Total 144 quadrupole magnets are installed in PLS. The magnets are connected in series with groups of two or 24. Each group is powered by a high-precision constant-current DC power supply. For the purpose of the beam based alignment of beam position monitors in the PLS, it is necessary to adjust the current of each quadrupole independently. To achieve this, a high current shunt regulator is designed. It can shunt a maximum 50 A of the quadrupole magnet current. The shunt regulator is programmable and the current amplitude can be varied linearly with a 12-bit resolution. Power transistors are used in the current shunt regulator. The operation of transistors is in linear region. The RS232C protocol is used for remote control and status report of the shunt regulator to the main control centre of the PLS. Preliminary result indicates that the calibration accuracy of the beam position monitor can be achievable in less than $10{\mu}m$.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 추계학술발표대회 개요집
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• pp.24-26
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• 2003

In this study EB(Electron Beam) welder was modified to apply EB welder to micro-joining with solder ball and Pt wire. The power and beam current of EB welder is 6kW, 100mA and the minimum current was 1mA. The minimum current of EB welder was modified to decrease the amount of beam current to 0.0lmA and the monitoring system to observe materials was made up. The control system and CAD/CAM software for e-beam direct writing was developed and the deflection beam was controlled without moving workpieces. the possibility of applying EB welder to micro-joining with solder ball and Pt wire was studied through this experiments.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.293-296
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• 2005

This paper is concerned with the sweeping damping controller for beam. The active damping characteristics can be enhanced by moving the damper along the longitudinal axis. In this paper, the equation of motion for a beam including a sweeping damping controller is derived and its stability is proved by using Lyapunov stability theorem. It is found from the theoretical study that the sweeping damping controller can enhance the active damping characteristics, so that a single damper can suppress all the vibration modes of the beam. To demonstrate the concept of the sweeping damping control, the eddy current damper was applied to a cantilever, where the eddy current damping can move along the axis. The experimental result shows that the sweeping eddy current damper Is an effective device for vibration suppression.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 추계학술발표대회 개요집
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• pp.79-81
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• 2004

In this study EB(Electron Beam) welder was modified to apply Ef welder to micro-joining for soldering and micro-brazing. The power and beam current of EB welder is 6kW, 100mA(60kV) and the minimum current was 1mA. The minimum current of EB welder was modified to decrease the amount of beam current to 0.0lmA and the monitoring system to observe materials was made up. The system is developed including teaching function for generating patterns. The control system and CAD/CAM software for EB direct writing was developed and the deflection beam was controlled without moving workpieces. the possibility of applying EB welder to micro-joining for soldering and brazing was studied through this experiments.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권1호
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• pp.38-44
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• 2003

In this study, the balance beam control subsystem, new type of construction machinery using the mechanism of CMG (control moment gyro), for the attitude control of an unstructured object such as a beam carried by a tower crane, is designed and implemented. The balance beam controller consists of a wheel spinning at high speed and an outer gimbal for controlling the attitude of the wheel. Two motors, one for the wheel and the other for the gimbal, are used. Applying force to the spin axis of the wheel, as an input of the system, leads the torque about the axis because of the gyro effects. This torque is used to control the attitude of the unstructured object in this study. For the stabilizer function, in addition, holding the load at the current position, the attitude of the wheel is freed by cutting the power applied to the gimbal motor of the balance beam controller, which result in the braking force to stop the load by gyro effect. The works presented here include the mechanical system of the balance beam controller, the remote controller, the servo controller and the control software for the system. We also present experimental results to show that the system we proposed is useful as a new construction machinery which can control the attitude of the beam hanging from a tower crane.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.216-226
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• 2015

The neutral beam injection generate ultra-high temperature energy in the tokamak of nuclear fusion. The neutral beam injection make up arc power supply, filament power supply and acceleration & deceleration power supply. The arc power supply has characteristics of low voltage and high current. Arc power supply generate arc through constant output of voltage and current. So this paper proposed suitable buck converter for low voltage and high current. The proposed buck converter used parallel switch because it can be increased capacity and decrease conduction loss. When an arc generated, the neutral beam injection chamber occur high voltage. And it will break output capacitor of buck converter. Therefore the output capacitor was removed in the proposed converter. Thus the proposed converter should be designed for the characteristics of low voltage and high current. Also, the arc power supply should be guaranteed for system stability. The proposed parallel buck converter enables the system stability of the divided low output voltage and high current. The proposed converter with constant output be the most important design of the output inductor. In this paper, designed arc power supply verified operation of system and stability through simulation and prototype. After it is applied to the 288[kW] arc power supply for neutral beam injection.