• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.53-65
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• 1995

입자화상 처리기법은 유체역학 분야의 정량적 유동가시화에 있어서 중요한 역할을 하고 있다. 회전 유동의 측면 사진을 찍을 때, 측정부의 볼록면 때문에 그 영상에서 광학적 변형이 일어나게 된다. 이러한 변형은 측정부의 형상은 물론 회전유동의 방향에 의해서도 큰 영향을 받는다. 정확한 유동장을 얻기 위해서 이러한 변형이 적절한 방법에 의하여 교정된다. 교정한 실험 데이터를 수치해석 결과와 비교해 보면 정량적으로 잘 맞는 것을 알 수 있다.

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.46-47
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• 2005

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1436-1441
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• 2006

Each type of optical sheets in a LCD module experiences a characteristic behavior for thermal loading and unloading. During thermal cycling, a polymeric behavior is reversible and recyclable, depending on a material stiffness critically affected by temperature and time. Some critical issues on temperature- and time-dependent themomechanical deformation of the polymeric sheet are addressed by finite-element thermal results, followed by structural simulation results in this study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.679-680
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.256-257
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• 2001

We measured the linewidth (FWHM) changes of the PQR laser against the diameter of the devices and the injection currents. We report the linewidth narrowing with increasing the PQR currents. A rough estimate of the line width behavior shows an inverse proportionality to the cavity length. The spectrum of $\frac{3}{4}$ circle cavity PQR laser is reported for the first time as well. The spectrum looks slightly different from that of the full circle device due to the structural distortion.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.198-199
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• 2001

본 논문은 스테레오 영상의 왜곡 현상을 분석하는 수학적인 해석 방법을 제안하였다. 스테레오 카메라의 중심과 투사기의 중심을 연결하는 직선이 스크린이 가지는 평면의 중심을 지나는 법선 벡터가 되고, 스테레오 카메라와 투사기의 두 렌즈의 광축이 스크린의 중심에 놓일 경우에 사진을 찍는 조건, 투영 조건 및 관측 조건에 해당하는 해석해를 유도하였다. 위 세 가지 조건에 따라 영상의 왜곡 정도가 바뀌게 되는데 왜곡을 최소한으로 만들 수 있는 조건식을 유도하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.10
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• pp.911-919
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• 2013

Evaluation of the effect of radial distortion for a holographic stereogram demands conducting an experiment which comprises rendering of a 3D obejc, acquisition of perspective images, rearrangement of the acquired images for hogel images and quality assessment of the observing image reconstructed from the holographic stereogram. We propose numerical implementation of this evaluation by a specially developed algorithm for modeling of all required steps. The modeling is done by using a numerical model of an optical engine for generation of radially distorted hogel images at various degrees of distortion. The distorted images are used to form the holographic stereogram and to make the numerically reconstructed images from the holographic stereogram which are observed by an observer at desired location. The reconstructed images are compared by using PSNR.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1320-1327
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• 2009

In stereoscopy using stereo camera system, the representative factors inducing stereoscopic depth distortions have been reported such as the inter camera distance, the convergence angle and the depth resolution. The image distance is just known to us as a factor related in optical system. In a point of view of depth distortion, it will be a factor inducing a stereoscopic depth distortion. In this paper, we focused on the proof of our opinion that the image distance is one of the weighted factors inducing depth distortion under orthostereoscopic condition.

• Current Optics and Photonics
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• v.6 no.5
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• pp.479-488
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• 2022

To account for the internal thermal effects of solid-state lasers, a method using a back propagation (BP) neural network integrated with a particle swarm optimization (PSO) algorithm is developed, which is a new wavefront distortion correction technique. In particular, by using a slab laser model, a series of fiber pumped sources are employed to form a controlled array to pump the gain medium, allowing the internal temperature field of the gain medium to be designed by altering the power of each pump source. Furthermore, the BP artificial neural network is employed to construct a nonlinear mapping relationship between the power matrix of the pump array and the thermally induced wavefront aberration. Lastly, the suppression of thermally induced wavefront distortion can be achieved by changing the power matrix of the pump array and obtaining the optimal pump light intensity distribution combined using the PSO algorithm. The minimal beam quality β can be obtained by optimally distributing the pumping light. Compared with the method of designing uniform pumping light into the gain medium, the theoretically computed single pass beam quality β value is optimized from 5.34 to 1.28. In this numerical analysis, experiments are conducted to validate the relationship between the thermally generated wavefront and certain pumping light distributions.

• Current Optics and Photonics
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• v.7 no.6
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• pp.745-754
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• 2023

In order to test the recognition ability and accuracy of a target imaging simulator under the irradiation of solar stray light in a laboratory environment, it needs to be fixed on a five-axis turntable during a hardware-in-the-loop simulation test, so the optical system of the simulator should have a long exit pupil distance. This article adopts a secondary imaging method to design a projection optical system suitable for thin-film-transistor liquid crystal displays. The exit pupil distance of the entire optical system is 1,000 mm, and the final optimization results in the 400 nm-850 nm band show that the modulation transfer function (MTF) of the optical system is greater than 0.8 at the cutoff frequency of 72 lp/mm, and the distortion of each field of view of the system is less than 0.04%. Combined with the design results of the optical system, TracePro software was used to model the optical system, and the simulation of the target imaging simulator at the magnitude of -1 to +6 Mv was analyzed and verified. The magnitude error is less than 0.2 Mv, and the irradiance uniformity of the exit pupil surface is greater than 90%, which meets the requirements of the target imaging simulator.