• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1429-1434
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• 2003

A number of dust particles are intruded into ODD(Optical disk drive) due to the flow caused by disk rotation and are adhered to a lens or disk surface. The space between the disk and the lens is being reduced. Someone indicates the problems of this drive that are relatively small data storing capacity and slow access time. In recent, the problems of this optical disk drive mentioned above are being solved by adding the speed of the disk's revolution, making the actuator high-speed or light, and making the beam spot size smaller than making the space narrow between disk and lens. These particle contamination affects seriously RF Signal, readout signal in an ODD. Especially, the affected parts by a particle contamination in an ODD's readout signal are objective lens and media.

• Journal of the Korea Society of Computer and Information
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• v.28 no.2
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• pp.19-25
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• 2023

In this paper, we propose a method for improving raw images captured in a low light condition based on deep learning considering the image signal processing. In the case of a smart phone camera, compared to a DSLR camera, the size of a lens or sensor is limited, so the noise increases and the reduces the quality of images in low light conditions. Existing deep learning-based low-light image processing methods create unnatural images in some cases since they do not consider the lens shading effect and white balance, which are major factors in the image signal processing. In this paper, pixel distances from the image center and channel average values are used to consider the lens shading effect and white balance with a deep learning model. Experiments with low-light images taken with a smart phone demonstrate that the proposed method achieves a higher peak signal to noise ratio and structural similarity index measure than the existing method by creating high-quality low-light images.

• Korean Journal of Optics and Photonics
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• v.34 no.6
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• pp.276-282
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• 2023

In this paper, we designed a lighting optical system using a freeform lens as a substitute for expensive gobo lighting. Unlike gobo lighting, freeform lens lighting does not use an image mask, and it can form and project an image directly on the lens surface using only a single lens, thus reducing the cost compared to gobo lighting. In order to verify the performance of freeform lens lighting with these advantages, we conducted an illuminance simulation. As a result, it was confirmed that it can replace gobo lighting because it has an illuminance distribution similar to the image we want to irradiate and a light efficiency of 47% similar to the performance of gobo lighting.

• Korean Journal of Optics and Photonics
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• v.17 no.3
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• pp.240-247
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• 2006

This paper discusses the optical system design for projection TV using LCOS type micro display, which provides the high resolution, slim depth, and a large screen of more than 60 inches. We analyzed the relationship between the illumination system, projection lens, color separation & recombination system, and micro display. From this quantitative analysis, the starting data for the optimum light engine was defined, and all optical systems were designed by an optimization process. Three RGB panels were proposed for a high luminence system, and the four prisms symmetrically located make equal optical path lengths for the RGB rays. This color separation & recombination system enables the a compact illumination system. Also, in order to the slim light engine with high resolution, the folded projection lens system was designed by inserting a mirror between projection lenses.

• New & Renewable Energy
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• v.5 no.3
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• pp.26-31
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• 2009

Using MBE growth method, GaAs/AlGaAs solar cell structure was grown. Deposited electrodes are Au/Ni/Ge for n-type and Au/Pt/Ti for p-type electrodes were deposited by E-beam evaporator. Indoor light concentrators were devised and fabricated in order to concentrate artificial solar rays. Also mirror and prism and Fresnel lens concentration system with solar simulator were devised and fabricated. Results of solar cell characteristics were measured with shutting system which can control the amount of light. Maximum power density was 2.13 W/$cm^2$ and maximum concentration was 124 sun, when mirror with Fresnel lens was used at $7854\;mm^2$ of shutter hole.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.255-264
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• 2022

The conventional spot-type UV curing machine configures a collimator optical system using a plurality of lenses so that the light beam is incident through an optical cable. In order to increase the transmission light efficiency, a collimator optical system composed of three or more lenses is required, and accordingly, it is difficult to align the optical system, and it is difficult to implement the system compactly. In this study, a single TIR lens collimator that can realize the same level of spot diameter and light efficiency as the conventional collimator optical system composed of three lenses was designed. Through this, the light efficiency at the curing area with the minimum illuminance deviation was 33.2 %, which was similar to the performance of the reference collimator optical system, and the illuminance deviation on the curing area was 18.8 %, ensuring acceptable performance. In addition, by arranging a fly-eye lens with field flattening function at the front end of the condensing lens, the effective curing area diameter was reduced from 5.0 mm to 3.0 mm, enabling higher curing energy density to be realized. In addition, it was confirmed that the illuminance deviation can be greatly improved to a level of 14.4%.

• Transactions on Electrical and Electronic Materials
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• v.18 no.1
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• pp.35-41
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• 2017

This study looks at optimizinge light redistribution to improve the overall illuminance uniformity of commercial IRED modules. To obtain uniform illumination over a prescribed rectangular area, a freeform surface lens was evaluated using TracePro. The LED light overall illuminance uniformity regulated in KSC 7658 was verified using Relux software. Experimental test results showed 0.81 overall illuminance uniformity for rectangular light distribution of LED lights having a radiation angle of $80^{\circ}$. After fabricating prototype IRED lights based on these simulation results, illuminance performance was observed when used as actual IRED lighting with a nighttime CCTV system. Image observation photographs of the prototype $80^{\circ}$ rectangular IRED lights confirmed that object images can be seen clearly owing to high overall illuminance uniformity, and that dark regions of the CCTV screen were not shown.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.190-196
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• 2004

ACR(All Clear Reflector), also widely referred to as FFR(Free Form Reflector), were designed in general and intelligent ways using a NUDBS surface for the mathematical modelling of the reflector shape and artificial intelligence as the optimum design algorithm. An ACR, which consists of a continuous surface reflector and clear outer lens, offers styling advantages and provides a high quality light performance. The clear outer lens of an ACR remains efficient even with a highly inclined shape, as in the design of a sports car, as well as the complete clearness of the reflector surface eliminates the nuisance of stray light caused by the steps between adjacent segments of multi-faced reflectors. The application of an ACR to low beam lamp was so sucessful to obtain the sharp cut-off with the lens-free single-surfaced-smooth reflector. The design technique of ACR was tested with all types of lamps, including low beams, high beams, and fog lamps.

• Journal of The Korean Astronomical Society
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• v.19 no.2
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• pp.63-68
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• 1986

In this paper we deal with the orientation and the deformation of the circular light bundle passing in a static bounded gravitational field. The properties of caustic of the gravitational lens are discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.494-498
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• 2016

In this paper, we proposed the 3-dimenstional (3D) analysis for calculating the optical characteristics of an autostereoscopic display with electric field driven liquid crystal (ELC) lens. From 3D analysis considering the slanting of lens, we calculate the cross-talk of each images and the distortion of viewing zone. Using geometric opics and extended Jones matrix method (EJMM), phase retardation of ELC lens according to position is calcuated and then optical path difference in 3D space considering tilt and azimuth angle of incident light is gotten. Then, intensity distribution is presented in the space. Through camparing the intensity distribution using ideal lens with the ELC lens, we identify the noise and image distortion of ELC lens. As a result, this analysis is expected to provide optimum design conditions for realistic and rigorous 3D display with ELC lens.