• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 춘계학술대회 논문집
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• pp.192-197
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• 1993

반도체 기억소자의 급격한 발전추세에 대응하기 위해서는 노광(exposure) 장비의 증첩정밀도 (overlay accuracy)가 같이 개선되어야 한다. 본 연구에서는 64M ERAM 제조를 목적으로개발된 스텝 퍼(stepper) 시스템의 성능평가 항목 중에서 증첩정밀도에대한 측정방법 및 현재까지의 연구결과를 기술하였다. 제작된 웨이퍼 정렬계는 off-axis 및 TTL 광학계와 이들 정렬신호에 따라 움직이는 웨이 퍼 구동계로 구성되어 있다. off-axis 광학계는 화상처리와 회절의 두 가지 방식이 가능하도록 설계 제작되었으며, TTL 광학계는 dual beam interferometric method를 이용하였다. 본 실험의 결과는 웨이퍼 정렬계의 특성을 평가한 것으로서, 현재까지 off-axis 정렬 방법만으로 얻은 증첩정밀도는 0.26-0.29$\mu$m (m+3 $\sigma$ )이다. 따라서 여기에 이미 제작되어 있는 TLL 정렬광학계를 추가로 사용하면 0.1 $\mu$m 이하의 정밀도에 이를 것으로 예측된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.565-569
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• 1993

In this paper, a specified number of actuators are selected from a given set of admissible actuators. The selected set of actuators is likely to use minimum control energy while required output variance constraints are guaranteed to be satisfied. The actuator selection procedure is an iterative algorithm composed of two parts; an output variance constrained control and an input variance constrained control algorithm. The idea behind this algorithm is that the solution to the first control problem provides the necessary weighting matrix in the objective function of the second optimization problem, and the sensitivity information from the second problem is utilized to delete one actuator. For variance constrained control problems, by considering a dual version of each control problem an efficient algorithm is provided, whose convergence properties turn out to be better than an existing algorithm. Numerical examples with a simple beam are given for both the input/output variance constrained control problem and the actuator selection problem.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.438-441
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• 2006

Since the behavior of structural members subjected to blast load shows different responses, the effect of impulse as well as peak load should be considered in the damage analysis. The threshold on P-I diagram that causes specific damage level divides the diagram into the failure zone and the non-failure zones. In this study, numerical analysis is performed based on single-degree-of-freedom (SDOF) techniques to generate rational P-I diagram considering material non-linearity and dual failure modes (flexure and direct shear) of RC beams. From the comparison with existing test results it is concluded that proposed numerical method is good to derive failure mode of RC beam under blast load.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1427-1429
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• 2008

In this paper, an illumination system design using two lamps was proposed to improve the brightness of the projector. The proposal is based on the results from optical simulation. The prism array was applied to maintain the same optical properties, such as brightness distribution for the divergence angle and the composed beam size of the system. These were compared to those of the one UHP lamp system. The brightness of the two-lamp system, having a panel size of 0.74" and an f/2.9, increased by a factor of 1.7 when compared to the brightness of one UHP lamp system.

• 한국광학회:학술대회논문집
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• 한국광학회 1991년도 제6회 파동 및 레이저 학술발표회 Prodeedings of 6th Conference on Waves and Lasers
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• pp.45-45
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• 1991

We describe a simple method for obtaining a narrow dip with subnatural linewidth in Doppler-free laser spectroscopy. The method is based on detecting the absolute magnitude, ｜Re[$\chi$NL($\omega$-$\omega$o)]｜, of the dispersive component (real part) of the nonlinear susceptibility induced by the pump beam, and the line shape recorded therefore exhibits a fully resolved technique and a dual phase lock-in amplifier, we have demonstrated the dip as narrow as 3 MHz in the laser-induced birefringence spectrum of the Na D1 line (natural linewidth 10 MHz). Possible spectroscopic applications are considered.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.441-441
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• 2012

Noise and vibration performance plays an important role in the development of rotating components, such as engines, drivelines, transmission systems, compressors and pumps. The presence of torsional vibrations and other specific phenomena require the dynamic behaviour of systems and components to be designed accurately in order to avoid comfort and durability related problems. This paper provides an overview of the instrumentation and challenges related to torsional vibration testing. The accuracy and performance of five measurement techniques (high-speed incremental encoder, dual beam laser interferometer, zebra tape, zebra disc, direct pulse measurements with magnetic probe) is investigated by measurements on a Fiat Punto 1.4 liter engine. The potential sources of error are discussed to explain the inaccuracies of each technique.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2005년도 추계학술발표대회 및 정기총회
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• pp.599-602
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• 2005

본 논문에서는 기존 단극성 원 빔 레이저 방식의 단점을 개선하기 위하여 듀얼 빔을 응용한 차량용 레이저 레이더 시스템을 설계하엿다. 양극성 m-시퀀스를 두 개의 레이저 파장에 할당함으로써 2차원 OOC(orthogonal optical codes)와 유사한 특성을 갖도록 하고 수신부에서 두 개의 단극성 신호를 차동구조를 이용하여 양극성 신호로 합성하는 방법을 이용, SNR 개선 방안을 제시한다. 시뮬레이션 결과, 제안한 듀얼 빔 방식이 기존의 원 빔 단극성 신호방식의 레이져 레이더 시스템에 비해 3dB의 SNR 개선이 가능함을 확인하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.25-28
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• 2007

Precise digital elevation model (DEM) is an important issue in coastal area where DEMs in a time series are especially required. Although LIDAR system is useful in coastal regions, it is not yet popular in Korea mainly because of its high surveying cost and national security reasons. Recently, precise coastal DEM have been made using radar interferometry, waterline method. One of these methods, Spaceborne imaging radar interferometry has been widely used to measure the topography and deformation of the Earth. We acquired ALOS PALSAR FBD mode (Fine Beam Dual) data for evaluating the quality of interferograms and their coherency. The purpose of this study is construction of DEM using the ALOS PALSAR data using radar interferometry and analysis of surface characteristics by coherence and magnitude map over the Ganghwado and Siwha tidal flats and near coastal lands.

• 천문학회보
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• 제36권2호
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• pp.60.1-60.1
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• 2011

We present the preliminary results of the pilot observations for the fringe survey at 43 GHz with the VLBI Exploration of Radio Astrometry (VERA). The main goals of the fringe survey are to establish a full list of phase calibrators for the VERA dual-beam astrometric observations, and for the KVN multi-frequency phase referencing observations. We performed two 24 hours experiments as a pilot observation to test the feasibility of the fringe survey. Each source from a list of 220 sources has been observed in one scan for 2 minutes. 67 sources were detected with the SNR threshold of 3.5. The correlated flux densities of the detected sources are presented in four ranges of projected baseline lengths.

• 한국광학회지
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• 제8권1호
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• pp.26-30
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• 1997

서로 수직으로 편광되고 두개의 종모우드로 발진하는 주파수가 안정화된 He-Ne 레이저를 이용하여 넓은 측정 범위를 갖는 헤테로다인 간섭계를 구성하였다. 두 모우드 사이의 맥놀이 주파수인 684MHz에 대한 라디오 주파수 간섭을 이용하여 약 .+-.1.74.mu.m의 분해능으로 광학매질의 광학두께를 측정할 수 있는 장치를 구성하였다. 이와 같은 측정장치를 이용하여 Nd:YAG 레이저의 수동형 Q-스위칭에 포화흡수체로 사용되고 있는 유기염료 박막의 두께와 국부적인 광학두께의 변화에 대한 map을 구할 수 있었다.