• Korean Journal of Optics and Photonics
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• v.28 no.4
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• pp.141-145
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• 2017

We design an F/1.8 smart -phone camera lens utilizing he Forbes aspherical-surface equation, which can effectively create a strong asphere, compared to the conventional, standard aspherical equation. We also describe the principal methodology and procedural steps of optical design to achieve specifications.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1516-1517
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• 2015

일반적인 시선추적 장치에서는 근적외선 카메라, 렌즈 및 근적외선 조명이 필수적으로 요구된다. 이에 본 연구에서는 저가의 소형 시선추적시스템 구성에 필요한 근적외선 카메라, 렌즈 및 근적외선 조명의 성능을 비교/분석하였다.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.601-605
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• 2009

Due to the fact that fish-eye lens can provide super wide angles with the minimum number of cameras, field-of-view over 180 degrees, many vehicles are attempting to mount the camera system. Camera calibration should be preceded, and geometrical correction on the radial distortion is needed to provide the images for the driver's assistance. However, vehicle fish-eye cameras have diagonal output images rather than circular images and have asymmetric distortion beyond the horizontal angle. In this paper, we introduce a camera model and metric calibration method for vehicle cameras which uses feature points of the image. And undistort the input image through a perspective projection, where straight lines should appear straight. The method fitted vehicle fish-eye lens with different field of views.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.999-1004
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• 2012

In this paper, camera modules and lens's images were analyzed for the compensation of distortion image by wide angle lens based WDR(Wide Dynamic Range) with high resolution sensor(2-Mega CMOS Image sensor). Due to wide angle ($176^{\circ}$) of designed wide angle camera modules, the compensation result of distorted image was analyzed, and the application of these modules was proposed for smart NUX(Natural User eXprience).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.1
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• pp.93-100
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• 2008

The parameters of lens such as focal length, focus, and aperture stop changes while shooting the scenes with zoom lens. Especially, zooming action dramatically changes the geometry of lens system that causes significant change of lens model. We investigated how the lens model changes while zooming in general shooting condition. Each parameters of lens model was estimated and checked whether they can be modeled well in the condition of auto-controlling focus, aperture and vibration reduction. In order to do this, calibration images were taken, modeled in different fecal length setting. And changing patterns of models were inspected to find out if there is some elements that have some particular pattern in changing with respect to focal length. The result showed us that although we didn't control the focus and aperture setting, there's specific changing patterns in radial and do-centering distortion. Especially, the strong linear correlation was found between coefficient of $r^2$ and focal length. It is expected that many parts of distortion can be eliminated without additional self calibration even if zoom operation is done when shooting the scenes if we know its fecal length and model of this coefficient.

• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.17-25
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• 2016

In this study, an optical system for a lens-shifting method that compensates for microvibration of a high-agility small satellite has been designed. The lens-shifting method is an image-stabilization technique that can be applied to compensate for the optical path disturbed by microvibration. The target optical system is designed by using Code-V, a commercial optical-design code. The specifications for real satellite cameras have established the requirements for optical design. The Ray aberration curve, spot diagram, and MTF curve were carried out to verify if the designed optical system meets the requirements or not. The designed Schmidt-Cassegrain optical system with field flattener and a vibration-reduction lens has been verified to meet the optical requirements, 33% of MTF at Nyquist frequency, GSD of 2.87 m, and vibration coefficient of 0.95~1.0.

• The Optical Journal
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• s.150
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• pp.21-30
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• 2014

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.269-274
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• 2002

최근에 TV의 축구, 야구와 같은 스포츠 중계 방송에서 팀의 로고나 점수, 거리와 같은 그래픽 정보를 운동장에 합성시켜 보여주는 새로운 기술이 사용되고 있다. 이는 증강현실(AR: Augmented Reality)의 한 분야인 실시간 이미징 합성 기법을 사용한 것으로서 일반적으로 가상이미징 시스템이라 불리운다. 본 논문에서는 방송용 카메라의 렌즈와 팬(pan), 틸트(tilt) 축에 센서를 부착하여 이를 해석함으로써, 실시간으로 3차원 그래픽 좌표계의 가상 카메라를 제어하는 센서기반 가상이미징 시스템의 구현 결과와 관련기술을 소개한다. KBS 기술연구소에서는 실시간 가상이미징 시스템을 개발하여 'VIVA(Virtual Imaging & Virtual Advertising)'라 이름지었다. 이 시스템은 렌즈 데이터에 근거하여 카메라 캘리브레이션을 수행하며, 주밍(zooming)시 발생하는 카메라의 시점(view point) 변화를 반영하여 원거리 촬영이 이루어지는 스포츠 중계뿐만 아니라 보다 정확성이 요구되는 스튜디오 내의 근거리 프로그램 제작에도 사용이 가능하다. 합성되는 그래픽은 실세계와 같은 완전한 3차원 좌표 공간에 놓이게 되며, 월드 좌표계와 카메라 좌표계를 이용하여 사전 제작된 오브젝트들을 원하는 곳에 위치시킬 수 있다. 실사와 그래픽의 효과적인 합성을 위하여 오버레이(overlay) 모드는 물론 알파키(alphakey)와 크로마키(chromakey)를 조합한 모드를 사용하였다. VIVA는 2002년 부산 아시안 게임에서 수영과 양궁 중계에 활용하였다.

• Korean Journal of Remote Sensing
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• v.19 no.6
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• pp.431-445
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• 2003

In this paper, we experimentally investigated the precision of 3D positioning using 4S-Van images in photograrmmetric perspective. The 3D calibration target was built over building facade outside and was captured separately by two CCD cameras installed in 4S-Van. After then, we determined the interior orientation parameter for each CCD camera through self-calibration technique. With the interior orientation parameter computed, the bundle adjustment was performed to obtain the exterior orientation parameters simultaneously for two CCD cameras using calibration target image and object coordinates. The reverse lens distortion coefficients were computed and acquired by least squares method so as to introduce lens distortion into epipolar line. It was shown that the reverse lens distortion coefficients could transform image coordinates into lens distorted image coordinates within about 0.5 pixel. The proposed semi-automatic matching scheme incorporated with lens distorted epipolar line was implemented with scene images captured by 4S-Van in moving. The experimental results showed that the precision of 3D positioning from 4S-Van images in photograrmmetric perspective is within 2cm in the range of 20m from the camera.

• The Optical Journal
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• s.104
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• pp.36-38
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• 2006

약 20여년간 글라스 렌즈 연마쪽에서 많은 노하우를 가진 광학전문업체를 모체로 2003년 설립된 (주)나오텍(대표·김영기)은 각종 카메라에 사용되는 완제품 렌즈를 생산, 국내 및 해외 시장에 판매하고 있다. 후발주자지만 끊임없는 교육과 재투자, 신경영기법을 적용한 적극적인 마케팅 활동 등으로 인지도를 넓혀나가고 있으며 짧은 시간동안 급성장을 이루며 탄탄한 내실을 다지고 있다.