• Korean Journal of Materials Research
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• v.28 no.4
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• pp.201-207
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• 2018

Infrared(IR) heating has many advantages, such as energy efficiency, reduced heating time, cleanliness, equipment compactness, high drying rate and easy automation. These features of IR heating provide widely industrial applications, such as surface heat treatment in semiconductor fabrication, thermoforming of polymers, drying and disinfection of food products, heating to metal forging, and drying of wet materials. In this study, the characteristics of a protected gold mirror were examined by spectrophotometer and the lifetime of the coating layers were evaluated by a cross-cutting method and salt spray test. The effects of manufacturing conditions on the protected gold mirror were seen and remedies for these effects were noted in order to improve the properties of the protected gold mirror in the drying process. The reflectance and lifetime of the protected gold mirror was influenced by manufacturing conditions, such as surface roughness and forming conditions of the anti-oxide layer, the adhesion layer, the reflecting layer and the protection layer. The results of this study showed that the protected gold mirror manufactured using a buffing method for pre-treatment resulted in the most effective reflectance. In addition, $Al_2O_3$ coating on an Al substrate as an anti-oxide layer was more effective than the anodizing process in the test of reflectance. Furthermore, the protected gold mirror manufactured by layers forming of various materials resulted in the most effective reflectance and lifetime when coated with $Al_2O_3$ as the anti-oxide layer, coated Cr as the adhesion layer, and coated $MgF_2$ as the protection layer.

• Korean Journal of Optics and Photonics
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• v.21 no.5
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• pp.214-223
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• 2010

Optimization of a 30 cm lightweight mirror was proposed with the best optical performance under various loads of gravity and thermal loads with proper boundary conditions. A pattern for a lightweight mirror was generated based on the best optical performance combined with ease of manufacturing for proper design parameters of physical properties of face sheet, back sheet, rib, and web. Evaluation of the optical performances of a telescope mirror was obtained by using the finite element analysis program, NX I-DEAS. Surface errors, individual aberration terms, such as piston, tilts, focus and other aberrations were calculated by using Zernike polynomials. The proposed telescope mirror meets well the opto-mechanical design consideration of RMS surface error less than 16 nm.

• Journal of the Korean Ceramic Society
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• v.46 no.1
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• pp.102-107
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• 2009

This study has been focused on an effective surface finishing method combining ELID (ELectrolytic In-process Dressing) and MAP (Magnetic Assisted Polishing) for the nano-precision mirror grinding of glass-lens molding mould. ELID grinding is an excellent technique for mirror grinding of various advanced metallic or nonmetallic materials. A polishing process is also required for elimination of scratches present on ELID grinded surfaces. MAP has been used as polishing method due to its high polishing efficiency and superior surface quality. It also presents some techniques for achieving the nanometer roughness of the hard material such as WC-Co, which are extensively used in precision tooling material.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.65-68
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• 1995

A slicing method by thin diamond blade is widely usd slicing of hard and brittle materials such as ceramics,glass and ferrite etc.. In this study, a new slicing system which realizes highly efficient and mirror surface slicing was developed by applying ELID-grinding with metallic bond diamond blades and its performance was evaluated. Hard and brittle materials such as ceramics,glass and ferrite were used as workpiece. Metallic bond diamond blades with grit sizes #325 and #2000 were used. Experimental results show that highly efficient slicing and good mirror surface can be successfully obtained using the developed slicing system with ELID features.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.82-88
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• 1997

In this paper, the development of a precision CNC lathe prototype for mirror surface machining is presented. To obtain high precision machining accuracy, a hydrostatically supported precision spindle and a sliding guideway with turcite pad are adopted as the motion elements. The machining accuracy of the prototype machine, and the motional accuracy of its motion elements are tested and evaluated to confirm the validity of the application of these elements on the prototype. The hydrostatic spindle shows 0.09 .mu. m of rotational accuracy and the guideway shows about 0.8 .mu. m/170mm of horizontal straightness. The sur- face roughness of cupper and aluminium cylinder machined by the prototype machine with diamond tool are 0.07 .mu. m and 0.10 .mu. m Rmax respectively. From these results, it is verified that the prototype lathe is avail- able for high precision machining.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.26-32
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• 2012

The purpose of this paper is to present the summary of trouble shooting result on the dendrite defect of SSM(Second Surface Mirror) which is one of major thermal control elements for satellite. Through this failure analysis on SSM dendrite, it is found that the dendrite defect may happen to silver coated layer of SSM if SSM is directly exposed to the environment containing sulfur or chlorine compound. As a preventive action, it is required that SSM shall not contact directly with rubber pad containing sulfur compound.

• 연구논문집
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• s.28
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• pp.59-71
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• 1998

The ELID(electrolytic in-process dressing) grinding method is a new precision grinding technique with the special electrolytic in-process dressing by metal bonded grinding wheel, fluid, and power supply. It is possible to make a efficient precision machining of hard and brittle materials such as ceramics, hard metals, and quenched steels by using this method, In this study, a new efficient precision grinding method with ELID was attempted for application to the machining and finishing processes of cylindrical structural components. And, we try to develop the cylindrical grinding technique for mirror surface of ceramics, tungsten carbide and SCM steel, and for the high efficiency grinding of machined parts, for example, ball screw shaft. Electrical characteristics of three different wheel grit sizes of #325, #2000 and #4000 were investigated experimentally. ELID grinding method is proved to be useful for mirror surface generation and efficient machining.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.22-27
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• 2010

The usage of ultra-precision machining is increasing by the manufacturing of precision optical elements such as camera lens, laser printer, CD player, DVD and microscope parts etc.. The WC alloy material is in wide use by mold core to improve the productivity and accuracy in manufacturing those precision parts. The WC alloy mould core can be machined effectively by the parallel grinding process which is an excellent technique for manufacturing of surface profile hard to machining materials such as the hardened metal alloy, Ceramics, Glass and so on. Magnetic assisted polishing as a final polishing process has also been utilized to obtain ultra-precision mirror surface with the elimination of traces presented on ground surface. It is able to deduce the optimal ultra-precision machining conditions of the WC alloy material from the experiment and analyses results.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.83-87
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• 2001

A 110 mm diameter aspheric metal secondary mirror for a test model of an earth observation satellite camera was fabricated by ultra-precision single point diamond turning (SPDT). Aluminum alloy for mirror substrates is known to be easily machinable, but not polishable due to its ductility. A harder material, Ni, is usually electrolessly coated on an Al substrate to increase the surface hardness for optical polishing. Aspheric metal secondary mirror without a conventional polishing process, the surface roughness of Ra=10nm, and the form error of $Ra={\lambda}/12({\lambda}=632nm)$ has been required. The purpose of this research is to find the optimum machining conditions for reflector cutting of electroless-Ni coated Al alloy and apply the SPDT technique to the manufacturing of ultra precision optical components of metal aspheric reflector.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.629-632
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• 2005

ELID(ELectrolytic In-process Dressing) grinding is an excellent technique for mirror grinding of various advanced metallic or nonmetallic materials. A polishing process is also required for elimination of scratches present on ELID grinded surfaces. MAP(Magnetic Assisted Polishing) has been used as a polishing method due to its high polishing efficiency and to its resulting in a superior surface quality. This study describes an effective fabrication method combining ELID and MAP of nano-precision mirror grinding for glass-lens molding mould, such as WC-Co, which are extensively used in precision tooling material. And for the optics glass-ceramic named Zerodure, which is extensively used in precision optics components too. The experimental results show that the combined method is very effective in reducing the time required for final polishing. The best surface roughness of the polished glass-ceramic was within 1.7nm Ra in this study.