• Korean Journal of Optics and Photonics
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• v.20 no.2
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• pp.81-86
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• 2009

Digital holography and refractive index difference are used to measure a high aspect ratio's patterns. When interference fringes are very closely spaced, the phase data containing high frequencies where $2{\pi}$ ambiguities cannot be resolved. In this technique, the optical path difference is decreased by decreasing the refractive index difference. As a result, we solve the $2{pi}$ ambiguities. Also, this technique is applicable to measure the refractive index if the shape of the sample is known.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.177-184
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• 2012

A hologram projects a 3 dimensional video as same as a real subject and it is made by principles of holography. Many researches about holographic technology have been developed. Studies for visualization of 3D videos, holographic storages, and optical media have proceeded mostly in engineering. It is hard to find any researches about the convergent system from the viewpoint of interactive elements and motion graphic design such as this paper's concept. Most studies of augmented reality have been developed in the domain of technology and education but the field of content production. AR has been convergent with various fields and media, so it is time to make an active progress in the study of convergent content development. The goal of this study is to develop cultural contents and create new values through the convergence of holography and AR. The purpose of this paper is to propose the way of developing the convergent type of cultural contents and construct the production system by the new approach to users using the convergence technology of holography and augmented reality.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1753-1756
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• 2007

In the field of 3D display, holographic displays are the only technology allowing optimal user comfort. We have developed systems based on compact projection optics, that allow advantageous new features, like large size full-color3D scenes generated at high rate on a micro-display with state of the art resolution.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.12
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• pp.22-27
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• 2015

Conoscopic holography, which consists of two linear polarizers and two wave plates, and an uniaxial crystal, is incoherent holographic technology for three-dimensional display. In the uniaxial crystal, the wave from object divides into extraordinary and ordinary waves and phase difference between two waves is caused by the different refractive index of two waves. Four intensity patterns, which are made by phase difference, are obtained using LCLV(liquid crystal light valve) and conoscopic holography system. By combining four intensity patterns, the complex hologram without bias and conjugate image. In this paper, we propose the optimized system, which consists of a wave plate and a linear polarizer, and uniaxial crystal. In the proposed system, it doesn't need LCLV. By adjusting the azimuth angle of a linear polarizer and a wave plate, we derive four intensity patterns in recording plane. We demonstrate theoretically that the complex hologram with bias and a conjugate image is obtained using the proposed system.

• International Journal of Advanced Culture Technology
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• v.7 no.4
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• pp.274-282
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• 2019

This paper discusses the main requirements in today's full-color holograms illumination and evaluates the last generation of LEDs, the actual best light source to render properly the colors of the holograms and in particular those recorded with red 660 nm, green 532 nm and blue 440 nm lasers. This paper presents also the first prototype of lamp designed especially for this kind of holograms.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.7-15
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• 2007

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1486-1489
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• 2007

Generally many kind of phase unwrapping method are used to obtain three-dimensional feature in digital holography. Goldstein algorithm is representative method. But Goldstein algorithm has some problems. We developed a modified Goldstein algorithm that could solve the problem of Goldstein algorithm using the boundary information. Obtained three-dimensional information can be applied to 3-D contents of stereoscopic, multi-view, SMV, or holographic display.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.169-171
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• 2008

마이켈슨 간섭계 시스템에 두 개의 Convex Lens를 추가함으로서 평면파 참조광을 유지 시키며, 물체에 조사되는 물체광의 조사면적을 변화시킬 수 있는 새로운 형태의 마이켈슨 간섭계를 제작 하였다. 새로운 형태의 마이켈슨 간섭계를 반사형 디지털 홀로그래피 현미경 시스템(Digital Holography Microscope System)에 적용하여 촬상소자(CCD: Charge Couple Device)에 홀로그램 기록 시 기록 가능한 CCD의 유효 영역과 재생 가능 영역에 대해 연구를 하였다

• ETRI Journal
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• v.40 no.3
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• pp.366-375
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• 2018

Recently, techniques involving head-mounted displays (HMDs) have attracted much attention from academia and industry owing to the increased demand for virtual reality and augmented reality applications. Because HMDs are positioned near to users' eyes, it is important to solve the accommodation-vergence conflict problem to prevent dizziness. Therefore, holography is considered ideal for implementing HMDs. However, within the Nyquist region, the accommodation effect is limited by the space-bandwidth-product of the signal, which is determined by the sampling number of spatial light modulators. In addition, information about the angular spectrum is duplicated over the Fourier domain, and it is necessary to filter out the redundancy. The size of the exit-pupil of the HMD is limited by the Nyquist sampling theory. We newly propose a holographic HMD with an expanded exit-pupil over the Nyquist region by using the time-multiplexing method, and the accommodation effect is enhanced. We realize time-multiplexing by synchronizing a high-speed digital micromirror device and a liquid-crystal shutter array. We also demonstrate the accommodation effect experimentally.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.1009-1017
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• 2011

Fast generation of digital hologram is of importance for real-time holography broadcasting. In this paper, we propose such a method that parallelizes the Computer-Generated Holography (CGH) algorithm for digital hologram generation and make it faster using Multi Graphic Processing Unit (Multi-GPU) with help of the Compute Unified Device Architecture (CUDA) and the Open Multi-Processing (OpenMP). In addition, we propose optimization methods such as fixation variable, vectorization, and loop unrolling for making the CGH algorithm much faster. Experimental results show that our method is about 9,700 times faster than a CPU-based one.