• Bulletin of the Korean Chemical Society
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• v.31 no.3
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• pp.653-663
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• 2010

Enantioselective total synthesis of (-)-clavosolide A and B was reported in full including the synthesis of proposed structure of (-)-clavosoldie A (1), revised structure of (-)-clavosoldie A (5), and revised structure of (-)-clavosoldie B (6). The relative and absolute stereochemistries of the natural products were confirmed unambiguously by comparing the optical rotation values and $^1H$ and $^{13}C$ NMR spectra of them.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.377-380
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• 2003

Recently, demand of digital products with optoelectronic device is increasing rapidly. A microlens array is applied to improve optical efficiency on optoelectronic device, and it is usually fabricated by photolithography and reflow process after planarization layer coating process. UV molding process is more suitable for mass production of high quality microlens array than photolithography and reflow process. In the present study, microlens array was fabricated on the simulated optoelectronic device with planarization layer by aligned UV molding process. The shape of replicated microlens was measured, and the section image of molded part was examined.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.134-139
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• 2001

Laser scanners are widely used for reverse engineering and inspection of freeform parts in industry such as motors, electronic products, dies and molds. Due to the lack of measuring software and positioning device, the laser scanning processes have been erroneous and inconsistent. In order to automate measuring processes, an automated scan plan generation software and a proprietary hardware are developed. In this paper, an automated laser scanning system using a 3-axis motorized stage is proposed. In the scan planning step, scan directions, paths, and the number of scans are generated considering optical and mechanical parameters. In the scanning step, the generated scan plan is downloaded into the laser scanner and the motorized stage and the points on the surface are captured automatically. Finally, the point data set is analyzed to evaluate the performance of the system.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.956-961
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• 2004

This paper proposes a study on the spherical lens manufacturing by simultaneous 3 axis for NC lathe. We use friction drive system for moving system in experimental diamond turing machine. The diamond turning machine use manufacturing for high quality lens, mirror and many optics products. Especially, the high tech industry require a lot of lens. For example, optical engineering. medical science, space engineering and material engineering etc. The friction drive system is very simple and quiet, compared to ball screw system. We find a problem at the simultaneous 3 axis and suggest a solution. Also, when we manufactured a micro lens. find a problem and solution.

• Design & Manufacturing
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• v.2 no.6
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• pp.38-42
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• 2008

Recently, the demands of digital camera and miniature camera module for mobile-phone is increased significantly. Lenses which is the core component of optical products are made by the injection molding(plastic lens) or GMP(glass lens). Plastic lens is not enough to improve the resolution and performance of optic parts. Therefore, the requirement of glass lens is increased because it is possible to ensure the high performance and resolution. In this paper, the thermal stress analysis of 3 cavity GMP mold for molding glass lens was performed for estimating the thermal stress and amount of deformation. Finally, the modification plan based on the analysis results was deducted.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.623-624
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• 2005

Micro injection molding is a branch of micro system technology and has been under development for the mass manufacture of micro parts. Enhanced technological products like micro optical devices are entering the market. This paper presents fundamental research on the injection molding technique in micro fabrication. In order to successful manufacturing of micro plastic parts, it is necessary to research for development of micro-injection machine, machining of micro mold, decision of optimum injection conditions and the research for polymer material. Therefore in this study, in order to machining of micro mold, a mold core with microscopic V-shaped groove was tooled by ultra-precise tooling machine. The transcription experiments with a polymer, PMMA resin on the surface of core with Ni plating were carried out and surface profile of injected parts was measured with AFM.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.9
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• pp.22-29
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• 1997

This paper describes a three dimensional profile measurement method for sheet metal products which have flexible and porous sculptured surfaces. Shadow masks are used as measuring objects for practical implementation or this study. The shadow masks are located inside the fluorescent glasses of monitors for televisions or computers and used to prevent electron guns from interfering between pixels. Three dimen- sional surface profiles are measured by adopting a software autofocusing technique to capture focused images. The experimental results show that the method is very effecive and suitable for sheet meal prod- ucts with flexible and porous surfaces.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.5 s.108
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• pp.36-43
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• 2004

The behaviors of deterioration in the mechanical and optical properties of paper during sunlight exposure are mainly attributed to UV irradiation. The effect of different additives (anti-UV agents) on paper properties during exposure was studied. The results showed negligible changes in the mechanical properties of samples prepared with two different ways, whereas the shielding ability was increased when the additives were applied to the surface of hand sheets. Also, the paper which is treated with anti UV agents can keep freshness more effectively of agricultural products from UV irradiation.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.104-107
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• 2005

COMS(Communication, Ocean, and Meteorological Satellite) is the geostationary satellite for the mission of satellite communication, ocean monitoring, and meteorological service. It is scheduled to be launched at the end of 2008. Ocean payload of COMS named as GOCI(Geostationary Ocean Color Imager) observes ocean color and derives the chlorophyll concentrlition, the concentration of dissolved organic material and so on. In operational oceanography, satellite derived data products are used to provide forecasting and now casting of the ocean and coastal water state. In this work, conceptual design of structural part of GOCI is carried out and two baseline concepts are proposed. The one is dioptric module that uses lens system and the other is TMA(Three Mirror Anastigmat) module that uses mirror system. Trade-off studies between two concepts are investigated by considering optical and mechanical performances. Finally, on-going tasks and future development plan are briefly discussed.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.205-207
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• 2009

LCD (liquid crystal display) industry is needed to goods of high reliability and is interested in products without harmful material. In this experiment, we made the LED backlight unit for Automotive-navigation. And for making this backlight unit we used to eight side emitting type white LEDs with 1W high power of the lumileds company. We could know that this backlight unit releases to 6500 nit in 14W power consumption and start up voltage time is under the15ms in the ambient temperature -20 $^{\circ}C$.