• Broadcasting and Media Magazine
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• v.24 no.2
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• pp.32-38
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• 2019

컴퓨터 생성 홀로그래피(CGH)는 광파의 진행을 수치적으로 시뮬레이션하여 홀로그램 영상을 합성하는 연구분야이다. 실물 기반 홀로그램으로는 제작하기 어려운 다양한 가상 장면을 다룰 수 있으며 복잡한 광학계 구축 문제로부터 자유로운 장점 등으로 인하여 많은 연구가 진행되고 있다. 특히 대규모 병렬 처리가 가능한 범용 GPU의 발전은 CGH 실용화의 견인차가 되고 있다. 본 고에서는 CGH의 원리 소개와 함께 GPU에 기반한 CGH 고속화의 이슈 및 향후 전망을 살펴보고자 한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.231-232
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• 2022

본 논문에서는 비디오 시퀀스 내에서 카메라의 움직임을 추적하고, 추적 데이터를 기반으로 2D 영상에 3D CG 객체를 추가하는 방법을 소개한다. 해당 객체가 시점을 고려한 장면 내의 피사체로써 간주되기 위해서는 3차원 가상공간 내에서 피사체의 위치를 기반으로 장면 내 기준 평면을 구성하는 점들과 카메라의 기저 축 좌표를 조정한다. 영상제작 현장에서 활용되는 소프트웨어에서 수작업으로 진행되는 과정을 살펴봄으로써 매치 무빙기법이 증강현실과 광학기반의 SLAM 등과 같은 다양한 응용분야에서의 활용을 고려할 수 있겠다.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.246-255
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• 2007

The floating image system (FIS) is a device to display input source in the space between fast surface of the display and an observer and it provides pseudo 3D depth to an observer when input source as real object or 2D image was displayed through the optical lens system in the FIS. The Advanced floating image system (AFIS) was designed to give more effective 3D depth than existing FIS by adding front and rear depth cues to the displayed stereogram, which it was used as input source. The magnitude of disparity and size of stereogram were strongly related each other and they have been optimized for presenting 3D depths in a non-optical lens systems. Thus, if they were used in optical lens system, they will have reduced or magnified parameters, leading to problem such as providing incorrect 3D depth cues to an observer. Although the size of stereogram and disparity were demagnified by total magnifying power of optical system, the viewing distance (VD) from the display to an observer and base distance (BD) for the gap between the eyes were fixed. For this reason, the quantity of disparity in displayed stereogram through the existing FIS has not kept the magnifying power to the total optical system. Therefore, we proposed the methods to provide correct 3D depth to an observer by compensating quantity of disparity in stereogram which was satisfied to keep total magnifying power of optical lenses system by AFIS. Consequently, the AFIS provides a good floating depth (pseudo 3D) with correct front and rear 3D depth cues to an observer.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.1-5
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• 2007

Wavelength-division multiplexed (WDM) networks are emerging to be the right choice for the future transport networks. In WDM networks, the optical layer provides circuit-switched lightpath services to the client layer such as IP, SONET and ATM. The set of lightpaths in the optical layer defines the virtual topology. Since the optical switches are reconfigurable, the virtual topology can be reconfigured in accordance with the changing traffic demand pattern at theclient layer in order to optimize the network performance. We present a new approach to the virtual topology reconfiguration and loadbalancing problem for wavelength-routed, optical wide-area networks under dynamic traffic demand. By utilizing the measured Internet backbone traffic characteristics, our approach follows the changes in traffic without assuming that the future traffic pattern is known. For the simulation traffic modeling, we collected the data from real backbone traffic. Experiments show that the standard deviation compared to previous technique is reduced.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.223-232
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• 2014

The feasibility of a virtual colored overlay is based on constraints of computer and user preference and it is evaluated for people with Scotopic Sensitivity Syndrome. We draw ${\alpha}$ and chromaticities of virtual colored overlay which will be implemented on IT devices by measuring optical characteristics of 2 representative film overlays and simulating them. We analyzed the influence of two illuminating conditions on the virtual colored overlay. We find that it is possible to get the multiple combinations of alpha and source RGB values to match a chromaticity which is presented in CIE-Luv color space under ideal white condition of display, a user can select one among them with respect to clarity and comfort. Under 100 lx difference of illumination conditions, the changes of chromaticities are negligible, but luminances are increased $37.8cd/m^2$ average(std 2.006) at high illumination condition.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.2
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• pp.43-50
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• 2008

Purpose: The purpose of this study is to evaluate the effect of a VR (Virtual Refractor), which is a simulator for a PR (Practical Refraction), as an educational tool. Methods: Twenty four third year students enrolled in the department of visual optics volunteered for VR education. Each student attended a VR training course and practiced with the VR by themselves. One month later, each student tested three virtual subjects on the VR and one real subject on the PR and were given a performance score for each refraction. And the scores for the virtual and practical refractions were compared. In addition, a self-report questionnaire based on a five point Likert-scale was designed, consisting of domains such as spontaneous participation, contribution for the refraction, confirmity of the VR and PR, and necessity of the VR. Results: The Spearman's correlation coefficient between the testing score of the practical and virtual refractions indicated a significantly correlation (R=0.71, p<0.001). In the questionnaire, the mean score of the domains was 3.67${\pm}$0.96 and it indicated that students expressed that using the VR was beneficial. The correlation value among these domains was a high significant level, 0.91~0.68 (p<0.001). Conclusions: Although the VR required certain improvements in its concentration and systematic approaches for practical situations, it showed a high correlation between the VR and the PR and represented a positive evaluation in the PR.

• The KIPS Transactions:PartD
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• v.10D no.1
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• pp.117-124
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• 2003

The system implemented in this paper partitions and stores specimen data captured by a light microscope on distributed or parallel systems. Users ran observe images on computers as we use a physical microscope. Based on the client-server computing model, the system consists of client, coordinator, and data manager. Three components communicate messages. For retrieving images, we implemented the client program with necessary functions for educational applications such at image mark and text annotation, and defined the communication protocol. We performed the experiment for introducing a tape storage which stores a large volume of data. The experiment results showed performance improvement by data partitioning and indexing technique.

• The Journal of the Korea Contents Association
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• v.7 no.8
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• pp.109-116
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• 2007

Motion Capture in multimedia contents of the imagination world is utilized in various field such as game, movie, TV. Motion Capture technology of most of game is utilized. As well as is more realistic if use motion Capture and superior time and monetary aspect than previous key frame (Key-Framing) way as well as can display screen that do dynamic, there is more excellent advantage in qualitative aspect. But, is utilizing in some specialty companies and use example was not informed much about problem when is very lacking, and utilize yet in learned circles. Extract motion data of various action using optic motion Capture of motion Capture equipment in this treatise, and investigated about problem that appear when applied in character that is different from a person.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.29.1-29.1
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• 2009

이 연구는 별 관측을 통해 점 퍼짐 함수(PSF)를 측정하고 나이퀴스트 주파수에서 변조 전달 함수(MTF)을 계산하여 주파수 영역에서 저궤도 광학 위성의 영상품질 평가방법을 도출하였다. 가상 별 영상을 생성하고 IRAF로 2차원의 점 퍼짐 함수를 얻었고 MATLAB으로 점 퍼짐 함수를 2차원 푸리에 변환하여 변조 전달함수를 계산하였다. 공간 영역에서는 점 퍼짐 함수의 모양을 통해서도 영상품질을 검증할 수 있다. Along/Across-Track의 모양이 일치하고 중심에서 좌우대칭이며 델타함수에 가까울수록 좋은 품질의 영상을 의미한다. Along/Across-Track의 점 퍼짐 함수 모양차이는 Line Rate나 Time Delay and Integration(TDI)의 오차에서 기인한다. 별을 점광원으로 본다면 점 퍼짐 함수를 정의하기 쉽고 Along/Across 방향을 동시에 측정 가능하다는 장점이 있다. 궤도상에서 별을 관측하는 것은 지상을 관측하는 것보다 대기 환경의 효과가 크지 않기 때문에 영상 품질 평가에 유리하다. Yaw Steering이나 Nadir Pointing과 같은 자세제어의 효과를 배제할 수 있으므로 자세제어의 효과가 상당 부분 제거된 영상품질을 분석할 수 있다. 지상관측시간이나 배터리 충전시간이 아닌 지구 본영에서 별을 관측하므로 임무에 방해받지 않는다. 지상관측과 같은 효과를 내고 TDI를 사용하는 환경을 구현하기위해 Line Rate를 고려한 자세 기동 방법에 대해 연구하였다. 큰 각도의 자세 기동이 예상되어 쿼터니안을 이용하여 Inertial Pointing하도록 자세 제어하였고, 자세 Slew Rate 구속조건 하에서 제어가 필요하다.

• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.432-440
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• 2007

Optical simulation methods such as a ray tracing technique have been widely used to predict the optical performances of collimating films for LCD backlight applications. It is necessary to optimize simulation conditions which have substantial effect on the simulation result in order to predict accurate performances of collimating films. We have set up a very simple backlight model consisting of a reflection film, a virtual flat light-source, and a prism film, which is a representative collimating film for backlight, in order to analyze the simulation conditions which are strongly correlated with the on-axis luminance gain and the viewing-angle characteristics of prism films. It was found that the dependence of the relative change in the on-axis luminance on the structure and material properties of collimating films can be derived from the above-mentioned simple BLU model and from simulation using it. However, the exact reflection property of the reflection film and the distribution of the incident light onto the optical film were found to be very important for revealing exact viewing-angle characteristics of collimating films.