• Journal of the Optical Society of Korea
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• v.4 no.1
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• pp.62-65
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• 2000

A new type of multi-viewing zone screen for multiview 3-D display is described. The screen is made by stacking a Fresnel lens and a reflective prism array plate. The screen performs both focusing and beam dividing functions and directs very narrow light beams to three viewing zones for three spectators. The results of experimental testing of the screen have demonstrated that current technology of Fresnel lens and prism grooves on PMMA(Ploymethyl Methacrylate) allows manufacture of screen having a pixel size of about 1-2 mm. This size is reasonable enough for a screen with dimensions about 1m size. Optical qualities of Fresnel lenses and grooved prism arrays achieve an angular resolution for the screen of several angular minutes.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.584-587
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• 2006

An energy generating greenhouse based on fluoropolymer envelope and fresnel lens is proposed. The outstanding properties of the fluoropolymer films make them very suitable for large scale solar applications. Extremely high optical transmission over the whole solar spectrum, combined with mechanical strength, and durability allows us to design a highly optimized greenhouses for both plant growing and energy generation. Systems such as photovoltaic triple junction cells are especially attractive since they have up to 35% efficiency with much less cell material when the sun beam is focused with concentrators such as fresnel lenses. Cooling such devices will enhance the efficiency and provide useful thermal energy that could be further utilized for various applications depending on the local demands. This article introduces the basic ideas and principles of the energy generating greenhouses as a first step towards the actual deployment of such systems under Korean environment.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1490-1493
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• 2007

We proposed the method to take 3D image having correct depths to the front and rear directions when the stereogram was displayed to an observer through an optical system. Since the magnified stereogram by lenses was not given correct depth to an observer despite having the same magnified disparity. Consequently, we achieved our goal by relations of compensated disparities to both directions with magnification of lenses, viewing distance and base distance of viewer in AFIS.

• Korean Journal of Optics and Photonics
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• v.23 no.5
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• pp.179-188
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• 2012

Lenses with an ultra wide angle of view are usually called fisheye lenses since a fish can see an ultra wide panoramic view under water. As the angle of view for these kinds of lenses reaches a wide angle, the illumination on an image sensor is reduced by a rapid drop. In this paper, we discuss the causes and the ways to correct for a rapid drop. First, it is treated for the sign convention of directional cosine vectors and normal vectors on the curved surface by means of analytic geometry. And, from the fundamental discussion for these vectors, the rapid illumination drop is numerically analyzed for various kinds of causes by utilizing geometrical optics and radiometry as well as Fresnel equations derived from electromagnetic boundary conditions. As a result, we are able to get the full understanding for the rapid illumination drop and to propose ways to correct effects due to an wide angle of view.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.22-23
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• 2007

We tried to find the possibility of mono-crystalline silicon solar cell for photovoltaic concentrating system which is major cost portion for PV system using fresnel lens. With solar simulator and I-V curve tracer, we analyzed maximum output characteristics and measured the temperature of concentrated area using infrared camera. Because of temperature increase, there was no merit when concentrating. But at low radiant power, it showed more efficient operation. The combination of heat-sink technology and tracking system to our concentrating PV system would give better performance results.

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.43-52
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• 1995

For massicely parallel optical interconnections, we propose three types of planar optical configurations for crossover photonic switching netweek, backboard optical signal distribution, and high speed packet address detection. The planar overalsy allow 2-D pixel arrays located on a wafer scale intergated circuit to be interconnected in a compact and vibrationally robust configuration. By the laser writing technique surface relief of microopical Fresnel lenses and multiplex gratigs used in the planar optics are successfully fabricated.

• Journal of Mechanical Science and Technology
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• v.17 no.2
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• pp.239-245
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• 2003

Ultra precision diamond cutting is a very efficient manufacturing method for optical parts such as HOE, Fresnel lenses, diffraction lenses, and others. During micro cutting, the rake angle is likely to become negative because the tool edge radius is considerably large compared to the sub-micrometer-order depth of cut. Depending on the ratio of the tool edge radius to the depth of cut, different micro-cutting mechanism modes appear. Therefore, the tool edge sharpness is the most important factor which affects the qualities of machined parts. That is why diamond, especially monocrystal diamond which has the sharpest edge among all other materials, is widely used in micro-cutting. The majar issue is regarding the minimum (critical) depth of cut needed to obtain continuous chips during the cutting process. In this paper, the micro machinability near the critical depth of cut is investigated in micro grooving with a diamond tool. The experimental results show the characteristics of micro-cutting in terms of cutting force ratio (Fx/Fy), chip shape, surface roughness, and surface hardening nea. the critical depth of cut.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.376-381
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• 2003

Ultra precision diamond cutting is a very efficient manufacturing method for optical parts such as HOE, Fresnel lenses, diffraction lenses, and others. During micro cutting, the rake angle is likely to become negative because the tool edge radius is considerably large compared to the sub-micrometer-order depth of cut. Depending on the ratio of the tool edge radius to the depth of cut, different micro-cutting mechanism modes appear. Therefore, the tool edge sharpness is the most important factor affecting the qualities of machined parts. That is why diamond especially mono-crystal diamond, which has the sharpest edge among all other materials is widely used in micro-cutting. The question arises, given a diamond tool, what is the minimum (critical) depth of cut to get continuous chips while in the cutting process\ulcorner In this paper, the micro machinability around the critical depth of cut is investigated in micro grooving with a diamond tool, and introduce the minimizing method of cutting depth using vibration cutting. The experimental results show the characteristics of micro cutting in terms of cutting force ratio (Fx/Fy), chip shape, surface roughness, and surface hardeing around the critical depth of cut.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.83-90
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• 2011

There are two main types of concentrating optical systems in use today: refractive types that use Fresnel lenses, and reflective systems that use one or more mirrors. Regardless of the chosen optical system, the result is concentrated sunlight being aimed at the sensitive face of the cell, to produce more energy from less photovoltaic material. In this paper, for the achieve trackerless CPV system, CPV module included that the spherical lens with reflect mirror makes it possible to achieve high and stable power generation performance for the high concentration photovoltaic power generation system and cope with the needs for a variety of shapes and sizes in flexible manners and that the multiple cavity assemble method greatly reduces costs. Development of these high performance multi-junction CPV module promises to accelerate growth in photovoltaic power generation.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.218-219
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• 2007

Silicon feed stock shortage have acted as major restraints for growth of photovoltaic industry. Concentrating photovoltaic (CPV) system will reduce the use of silicon PV materials. This paper presents the application possibility of mono-crystalline silicon solar cell, which has increased in market share, for PV concentrator. We measured the power of solar cell using sun simulator and I-V curve tracer and compared the results. The comparison of results showed that the concentrated solar cell generated the power more approximately 7 times than without concentration in spite of non-heat sink. If CPV technology included heat sink combines already developed PV tracking system, it will have a merit economically.