• The KIPS Transactions:PartB
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• v.14B no.6
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• pp.423-430
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• 2007

Optical coherence tomography(OCT) is a high resolution imaging system which can image the cross section of microscopic organs in a living tissue with about $1{\mu}m$ resolution. In this paper, we implement OCT system and acquire 2-D images of rat eye and human molar samples especially in the field of opthalmology and dentistry. In terms of 2-D images, we reconstruct 3-D OCT images which give us another inner structural information of target objects. OPEN-GL reduces the 3-D processing time 10 times less than MATLAB.

• 한국지형공간정보학회:학술대회논문집
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• 1994.10a
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• pp.42-46
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• 1994

In this paper, we studied on an efficient detection and removal of the periodic scanner interference noise in LANDSAT images. Firstly, noise models and their characteristics are discussed. And we proposed a new scheme of noise detection in Fourier domain. Then, an dfficient noise filter can be designed based on the detected noise components. To verifythe effectiveness of our scheme, some experiments guided by our proposed scheme are performed using a real LANDSAT image.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.229-231
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• 2018

디지털 홀로그래픽 디스플레이 시스템의 홀로그램 영상 재현과정에서는 간섭 성 광원을 사용하는 것이 일반적이다. 간섭 성 광원의 높은 결맞음성으로 생겨나는 스페클 분포는 육안으로 쉽게 관찰 되는데, 이는 재현된 홀로그램 영상 품질 저하의 주요한 원인이 된다. 본 논문에서는 수평 360 도 전 방향에서 입체영상의 관찰이 가능한 테이블 탑 홀로그래픽 디스플레이 시스템에서의 스페클 분포를 측정하며, 이를 정량적으로 평가하기 위한 측정 방법을 기술한다. 객관적인 스페클 정량 지표로서 스페클 대조비를 구하여 테이블 탑 홀로그래픽 디스플레이 시스템에서의 스페클 분포를 계측하고, 이를 저감하기 위한 방법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4C
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• pp.524-532
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• 2004

In this paper, an incoherent holographic 3D imaging and display system based on the modified triangular and Mach-Zehnder interferometers is optically implemented and some experiments are carried out. Incoherent hologram of a 3D object is generated by using the hologram input system of modified triangular interferometer. Then this complex hologram is reconstructed by using the hologram output system of modified Mach-Zehnder interferometer in which two LCD spatial light modulators and a waveplate are inserted. From the experiment with two point sources having a depth difference of 100 mm each other, it is revealed that each point source can be independently reconstructed at its own focal position from the complex hologram, while both of the bias and conjugate image are simultaneously eliminated at the same time. And in the experiment with the real 3D object of two dices having a depth difference of 30 mm each other, it is also conformed that the bias and conjugate image can be effectively eliminated from the hologram pattern and each 3D dice can be also successfully reconstructed at its own focal position from the complex hologram. These experiment results finally suggest a possibility of implementing a new incoherent holographic 3D imaging and display system using the modified triangular and Mach-Zehender interferometers.

• Korean Journal of Optics and Photonics
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• v.29 no.3
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• pp.99-103
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• 2018

Optical coherence elastography (OCE) is based on optical coherence tomography (OCT), which is a noninvasive, high-resolution, cross-sectional imaging technique. In this paper, we have developed dynamic optical coherence elastography to measure elasticity, a mechanical property of tissue, by phase difference. A piezoelectric actuator was used for sinusoidal mechanical loading of samples. Before applying this method to biomaterial, we assessed the feasibility of OCE with samples of sponge, eraser, and sharp lead. Cross-sectional and phase-difference images of the sample were obtained under sinusoidal loading. The strain rate was calculated from the phase-difference information. To obtain the envelope of the phase-difference oscillations along the horizontal direction, Hilbert transformation was performed at each depth. The elevation of the envelope was represented by color mapping, and we could measure the relative elasticity within the sample by comparing the elevations. Finally, there was an advantage when we calculated the shear rate using self-interference in the sample arm, instead of the interference between sample and reference arms.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.10
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• pp.1-6
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• 2009

We derive the phase error of hologram due to imperfection of a wave plate, the azimuth angle error of a wave plate, and the azimuth angle error of a linear polarizer. Also, we analyze the effect of phase error by the modified triangular interferometer in case of 3-D image reconstruction of hologram.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.209-213
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• 2001

In this paper, we analyzed the radio interference between Bluetooth and Wireless LAN/video transmitter in the 2.4GHz band with Monte-Carlo Method. The simulation results show that it is necessary to limit under 10mW of the Bluetooth power to avoid the harmful interference between Bluetooth and Wireless LAN/video transmitter.

• Korean Journal of Remote Sensing
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• v.18 no.4
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• pp.209-220
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• 2002

We carried out studies on SAR image intensity and interferometric phase over oyster sea farms. Strong backscattering was observed in amplitude images, and that was considered as a radar signal double bouncing from horizontal bars. These sea farming structures are not visible in satellite optical images except IKONOS image, so that it demonstrates the value of radar remote sensing as an effective tool in support of sea farm detection. The intensity of the image is sensitive to system parameters including wavelength, polarization, and look direction, but does not correlate to tide height. We found that the strongest backscattering can be obtained by L-band HH-polarization with a look direction perpendicular to the horizontal bar. We also succeeded in generating 21 coherent JERS-1 SAR interferometric pairs over the oyster farms. The general trend of the fringe rate of the interferometric phases appeared to be governed by altitude of ambiguity. The general trend was modeled by an inverse function and removed to have a residual phase. The residual phase showed a linear relation with the tide height. The results demonstrate for the first time that SAR can possibly be used to estimate sea level. However, the r.m.s. error of a regression line is 11.7 cm, and that is so far too large to make reliable assessments of sea level in practical applications. Further studies is required to improve the accuracy specifically using multi-polarization SAR data.

• 전기의세계
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• v.42 no.6
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• pp.26-31
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• 1993

레이저 계측의 광범위한 분야에서 홀로그래픽 간섭법과 전자스펙클무늬 간섭법을 중심적으로 살펴보았다. 이 방법들은 거친 표면을 갖는 다양한 물제에 대해 간섭적 방법에서 가능한 정밀도로 측정 할 수 있으므로 매우 폭넓은 응용가능성을 가지고 있고 지금도 새로운 아이디어들이 제시되고 있다. 특히 ESPI는 CCD카메라의 발전과 영상처리기술의 발전에 따라 피파괴검사 분야에서 중심적인 역할을 할 것으로 전망된다. 그러나 국내에서는 이제까지 이러한 첨단계측법들이 산업기술분야에서 별로 활용되지 못하고 있는 실정으로 가까운 장래에 큰 역할을 할 것으로 기대해 본다.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.120-133
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• 1994

홀로그래픽 간섭계측기로터 나오는 영상 데이터를 해석하는 전문가시스템에 대하여 기술하였다. 그동안 간섭 띠무늬(fringe)를 해석하는 방법들이 어느 정도의 자동화를 이룩하며 개발되어왔다. 그러나, 복잡한 간섭 띠무늬 패턴(fringe pattern)및 심한 잡음이 생기게 되는 고속도 항공공학 분야 또는 실험기계공학 분야에서는 신뢰할 만한 자동화를 이룩하기가 매우 힘들었다. 현재 사용가능한 방법중에는 간섭띠무늬 추적, 위상전이, 푸리에 변환, 회귀분석 등이 있는데, 이들은 소음제거나 데이터 수정을 하는데 있어서 극히 국부적인 정보에만 의존하였다. 결과적으로, 특별히 심한 소음이 있는 경우, 부정확한 위상중첩이나 간섭띠무늬 순차배열문제에 부딪히게 되고 따라서 작업자의 수작업이 심각하게 필요하게 된다. 본 논문에서는 간섭띠무늬 추적방법의 자동화 를 위한 새롭고 포괄적인, 규칙기반 전문가시스템에 대하여 기술하였다. 새로 개발된 전문가 시스템은 간섭띠무늬 패턴에 대한 전체적인 또는 지연적인 정보를 추출해 내고 또 전문가가 가지고 있는 지식을 이용한다. 이 전문가 시스템은 저수준 및 고수준 처리를 동시에 할 수 있도록 상호연결기구를 채택하여 간섭띠무늬를 해석하는 적절한 해결책을 마련하였다. 또한 위상전이나 푸리에 변환 방법에서 문제가 되는 자동위상 중첩에 대해 개발된 전문가 시스템의 응용의 가능성에 대해서도 기술하였다.