• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.822-824
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• 2005

This paper presents a scheme to solve the congestion problem using phase-shifting transformer(PST) in power systems. Available transfer capability(ATC) is an important indicator of the usable amount of transmission capacity accessible by several parties for commercial trading in power transaction activities. This paper deals with an application of optimization technique for ATC calculation. Sequential quadratic programming(SQP) is used to maximize power flow of tie line subject to security constraints such as voltage magnitude and real power flow. The proposed method is applied to 10 machines 39 buses model systems to show its effectiveness.

• 한국산업정보학회논문지
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• 제23권4호
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• pp.13-22
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• 2018

본 논문에서는 스크램블 연산(Scramble Operation) 및 위상 천이 디지털 홀로그래피(PSDH; Phase Shift Digital Holography) 기반 영상 이중 암호화 방법을 제안한다. 암호화하고자 하는 영상을 스크램블 연산을 통해 디지털적으로 1차 암호화를 수행한 후, 위상 변조하고, 위상을 천이시킨 기준파와의 간섭을 통해 2차 암호화 정보를 얻는다. 복호화 과정은 암호화 과정의 역순으로 진행된다. 두 개의 암호화된 영상들을 적절하게 산술 처리하는 위상 천이 디지털 홀로그래피 기술을 통해 디지털적으로 1차 복호화하고, 위상 복조를 한 후, 스크램블 연산 시에 사용한 암호화 키 정보를 이용하여 원래의 영상을 복원한다. 제안된 암호화 방법은 스크램블 연산에 사용된 두 개의 키 정보와 위상 천이 디지털홀로그래피 기술에서 사용된 거리 정보, 광원의 파장 등의 정보를 모두 정확하게 알아야만 원래의 영상을 복원할 수 있다.

• 한국통신학회논문지
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• 제26권12B호
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• pp.1733-1740
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• 2001

A monolithic 5 GHz image reject mixer using a 0.5-m GaAs MESFET technology is designed and simulated. The Mixer exhibits a 13.56 dB down-conversion gain, a SSB (Single SideBand) noise figure of 11.91 dB, an input IP3 (third order intercept point) of -3.73 dBm and a PldB (1-dB compression point) of -11.0 dBm. The critical issue in the image reject mixer is the phase accuracy and magnitude balance of the 90 phase shifting network. The proposed image reject mixer realizes a 90 phase shifter on chip. This phase shifting network does not need any phase adjusting to achieve the phase error specification of 3 over a frequency range from 800 MHz to 1GHz. The simulated overall image rejection ratio is better than 50 dB.

• 한국생산제조학회지
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• 제8권6호
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• pp.78-83
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• 1999

This study discusses a non-contact optical technique, electronic speckle pattern interformetry(ESPI), that is well suited for in-plane and out-of-plane deformation measurement. However, the existing ESPI methods that are based on dual-exposure, real-time and time-average method have difficulties for accurate measurement of structure, due to irregular intensity and shake of phase. Therefore, phase shifting method has been proposed in order to solve this problem. About the method, the path of reference light in interferometry is shifted and added to least square fitting method to make the improvement in distinction and precision. This proposed method is applied to measure in -plane displacement that is compared with the previous method. Also, Used as specimen AS4/PE따 [30/=30/90]s was analyzed by ESPI based on real-time to determine the characteristics of vibration under no-load and tension. These results are quantitatively compared with those of FEM analysis inmode shapes.

• 한국산업정보학회논문지
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• 제22권4호
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• pp.1-9
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• 2017

본 논문에서는 위상 천이 디지털 홀로그래피(PSDH; Phase-Shifting Digital Holography) 및 디지털 워터마킹(Digital Watermarking) 기반 디지털 홀로그램의 이중 암호화 기술을 제안한다. 이를 위해 먼저 디지털 워터마크에 사용할 로고 영상을 정하고, 이 영상에 대한 이진 위상 컴퓨터형성 홀로그램(CGH; Computer Generated Hologram)을 반복 알고리즘을 이용하여 설계한다. 그리고 랜덤하게 발생시킨 이진 위상 마스크를 워터마크로 정하고, 설계된 이진 위상 CGH와 XOR 논리연산을 통해 워터마크 정보에 대한 키 영상을 생성한다. 그리고 물체 영상을 위상 변조하여 세기가 일정한 함수로 만든 후, 워터마크인 랜덤하게 발생시킨 이진 위상 마스크를 곱하여 물체파를 생성한다. 이 물체파는 워터마크 정보가 포함된 잡음과 유사한 패턴을 가지는 1차 암호화된 영상이라고 할 수 있다. 이를 2-단계 PSDH기술을 적용하여 기준파와 간섭을 시키면 가시성이 향상된 최종 간섭무늬를 얻는다. 이 간섭패턴이 최종적으로 구하고자 하는 물체 영상의 2차 암호화된 영상이 된다. 암호화된 영상의 복호화는 2-단계 PSDH기술을 통한 암호화된 영상들을 이용하여 적절한 산술연산 처리한 후, 프레즈넬 변환 및 1차 암호화 과정의 역순으로 진행하면 된다. 제안된 방법의 암호화 및 복호화 기술은 컴퓨터 시뮬레이션을 통하여 검증된다.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.409-414
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• 2010

This paper describes the surface form measurement of a spherical smooth surface by using single shot off-axis Fizeau interferometry. The demodulated phase map is obtained and unwrapped to remove the $2\pi$ ambiguity. The unwrapped phase map is converted to height and the 3D surface height of the surface object is reconstructed. The results extracted from the single shot off-axis geometry are compared with the results extracted from four-frame phase shifting in-line interferometry, and the results are in excellent agreement.

• 제어로봇시스템학회논문지
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• 제19권12호
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• pp.1089-1093
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• 2013

Depth extraction using the structured illumination method is popularly applied since it has the benefit of measuring the object without contact. With multiple spatial frequencies and phase-shifting techniques, it is possible to extract the depth of objects with large discontinuity. For applications such as 3D (Three Dimensional) displays, 3D information of the object is required and is useful if corresponding to each view of the display. For this purpose, hypercentric optics is appropriate to measure the depth information of an object with a large field of view that is applicable for a 3D display. By experiment, we present the feasibility for phase-shifting profilometry using hypercentric optics to obtain the depth information of an object with the field of view appropriate for a 3D display.

• 한국정밀공학회지
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• 제20권10호
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• pp.12-21
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• 2003

• ETRI Journal
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• 제38권4호
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• pp.599-605
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• 2016

For the implementation of a real-time holographic camera, fast and automatic holographic image reconstruction is an essential technology. In this paper, we propose a new automatic depth-detection algorithm for fast holography reconstruction, which is particularly useful for optical scanning holography. The proposed algorithm is based on the inherent phase difference information in the heterodyne signals, and operates without any additional optical or electrical components. An optical scanning holography setup was created using a heterodyne frequency of 4 MHz with a 500-mm distance and 5-mm depth resolution. The reconstruction processing time was measured to be 0.76 s, showing a 62% time reduction compared to a recent study.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.363-367
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• 2010

A new two step on-axis digital holography (DH) is proposed without any assumptions, phase shifting, or complicated optical components. A dual-channel Mach-Zehnder interferometer was employed. Using that setup, the object field can be reconstructed requiring only two step measurements. To eliminate position difference between two charge-coupled device (CCD) cameras, a matched filter algorithm was used. Experimental results are compared to those of the traditional phase shifting technique. The proposed approach can also be applied to single-exposure on-axis DH for real time measurement.