• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.95-96
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.71-72
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• 2011

• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.46-52
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• 2011

A confocal microscope was developed utilizing a scanning sample stage based on a home-built double-compound flexure guide. A scanning sample stage with nano-scale resolution consisted of a double leaf spring based flexure, a displacement amplifying lever, a Piezo-electric Transducer(PZT) actuator and capacitance sensors. The performance of the two-axis stage was analyzed using a commercial finite element method program prior to the implementation. A single line laser was employed as the light source along with the Photo Multiplier Tube(PMT) that served as the detector. The performance of the developed confocal microscope was evaluated with a mouse ear skin imaging test. The designed scanning stage enabled us to build the confocal microscope without the two optical scanning mirror modules that are essential in the conventional laser scanning confocal microscope. The elimination of the scanning mirror modules makes the optical design of the confocal microscope simpler and more compact than the conventional system.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.10a
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• pp.145-149
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• 2006

반도체의 고집적화와 LCD의 대형화로 인해 웨이퍼 및 LCD 검사용 스테이지의 성능 향상이 요구된다. 본 논문에서는 고속의 검사속도, 서브마이크론의 검사 정밀도, 그리고 대행정 구동을 위한 이중 서보 시스템을 제안하였다. 이중 서보 시스템은 선형모터로 구동되고 공기베어링으로 가이드 되는 조동 구동부와 보이스 코일 모터(VCM)로 구동되고 공기베어링으로 가이드 되는 미세 구동부로 구성된다. 검사 효율을 향상시키기 위한 고속 세틀링을 위한 제어기로서 시간 최적 제어 기법과 시간 지연 제어기를 결합한 모드 변경 제어기를 제안하고 이중 서보 시스템에 구현하여 성능을 평가하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.969-972
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• 2004

This paper describes the mechanism of parallel micro machine platform and its feedback control system for acquiring high accuracy. The parallel micro machine platform that has developed has 5x5x5 work-space and sub-micron accuracy. For the high accuracy, the feedback control system is important but errors in machining and assembling are inevitable. Kinematic calibration is important for this reason. In this paper, various error components are introduced and the effects of error component are analyzed.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.237-239
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• 2003

이 논문은 이중 출력과 단일 역률 적용에 대한 하나의 전력단 회로를 사용한 새로운 정류기를 나타낸다. 제안된 정류기는 부스트와 플라이백 컨버터가 결합된 하나의 전력단 회로를 갖는 구조를 가지고 있고, PFC(power factor correction) 와 일정 출력 전압 제어를 동시에 수행한다. 따라서, 제안된 정류기는 전형적인 AC/DC 정류기들(멀티 권선을 갖는 플라이 백 정류기, 투 스테이지 방식을 사용한 부스트와 플라이백 컨버터가 결합된 정류기 등등)보다 낮은 비용과 작은 사이즈의 장점을 갖는다. 제안된 정류기 회로의 동자 원리는 본 논문에서 상세하게 기술 되어진다. 그리고 시뮬레이션을 통하여 제안된 정류기의 타당성을 증명하였다.

• Annual Conference of KIPS
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• 2002.04b
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• pp.1293-1296
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• 2002

본 연구에서는 서브 스위치를 이용한 오류허용 정렬 네트워크를 제안한다. 기존의 정렬 네트워크에서는 여분의 경로와 네트워크의 복잡성문제가 있었다. 제안된 구조에서는 여분 경로를 확장시키기 위해서 각 스테이지마다 $\frac{N}{4}\sum\limits_{i=0}^{n=2}{(\frac{1}{2})}^i$ (N=입 출력수) 서브 스위치를 추가함으로써 여분의 경로가 $3^{n(n+1)/2}$만큼 증가하였다. 또한 제안된 정렬 네트워크는 기존의 네트워크의 이중 네트워크 plane 개념에서 사용한 스위치 소자와 링크 수와 비교해 볼 때 제안된 구조의 단일 plane을 이용한 구조가 복잡도에서 낮다. 결론적으로 제안된 서브 스위치를 이용한 오류 허용 정렬 네트워크는 여분의 경로를 증가시키면서 하드웨어적 복잡도를 감소시킬 수 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1883-1886
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• 2005

In this paper, a decoupled dual servo (DDS) stage for ultra-precision scanning system with large working range is introduced. In general, dual servo systems consist of a fine stage for short range and a coarse stage for long range. The proposed DDS also consists of a $XY\theta$ fine stage for handling and carrying workpieces and one axis coarse stage. Its coarse stage consists of air bearing guide system and a coreless linear motor with force ripple. The fine has four voice coil motors(VCM) as its actuator. According to a VCM's nature, there are no mechanical connections between coils and magnetic circuits. Moreover, VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about $25mm^2$. To break that hurdle, the coarse stage with linear motors is used to move the fine about 500mm. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. With MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. And for their movements without any frictions, guide systems of the DDS are composed of air bearings. To get precisely their positions, a linear scale with 5nm resolution are used for the coarse stage's motion and three plane mirror laser interferometers with 5nm for the fine's $XY\theta$ motions. With them, on scanning the two stages have same trajectories. The control algorithm is named Parallel method. The embodied ultra-precision scanning system has sub 100nm following error and in-positioning stability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4405-4410
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• 2015

Two-dimensional displacements are obtained from the sandwiched patterns, which superpose two linearly-periodic patterns orthogonally, respectively. The transparent top pattern is identified by deflection of the laser beam due to a difference of refractivity and the opaque bottom pattern is identified by deviation of the beam intensity due to a difference of reflectance. In the sample setup, the top pattern made up of build-up film is manufactured by UV laser machining and the bottom pattern is manufactured by ultra-precision trench machining and deposition for aluminum plate. The proposed decoding method is verified experimentally using the $10{\mu}m$ equally spaced sample patterns and the devised optical system. The Korea Academia-Industrial cooperation Society.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.129-135
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• 2006

In this study, a two-axis ultra-precision stage driven by piezoelectric elements is presented. The stage has a flexure-type parallel linear guide mechanism consisting of quad-symmetric simple parallel linear springs and quad-symmetric double compound linear springs. While the simple parallel linear springs guide the linear motion of a moving plate in the stage, the double compound linear springs follow the motion of the simple parallel linear spring as well as compensate the parasitic motions caused by the simple parallel linear springs. The linear springs are designed by rectangular beam type flexures that are deformed by bending deflection rather than axial extension, because the axial extension is smaller than the bending deflection at the same force. The designed guide mechanism is analyzed by finite element method(FEM). Then two-axis parallel linear stage is implemented by the linear guide mechanism combined with piezoelectric elements and capacitance type displacement sensors. It is shown that the manufactured ultra-precision stage achieves 3 nm of resolution in x- and y-axis within 30 ${\mu}m$ of operating range.