• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.3
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• pp.43-49
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• 2010

Recently, the use of fumigants for pest control of paper cultural heritages are limited because of the high toxicity of fumigants and the production of environment-harmfully compounds. Therefore, many non-chemical methods have been discussed and experimented. And it is recently focused on gamma radiation, which is one of non-chemical methods, for pest control of paper cultural heritage in Korea. In this paper, we carried out a gamma ray irradiation of papers including Hanji, copy paper, filter paper and then analyzed a physical properties and optical properties of paper sample to estimate the effect of gamma ray irradiation on paper properties. In result, gamma radiation have adverse effect on a physical properties and optical properties of paper, especially Hanji. Therefore, we have to carefully consider about using of gamma ray for pest control of paper cultural heritages.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.473-473
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• 2010

Plasma is widely used in various commercial etchers and chemical vapor deposition. Unfortunately, real-time plasma process monitoring is still difficult. Some methods of plasma diagnosis is improved, however, it is possible for real-time plasma diagnosis to use non-intrusive probe only. In this research, the object is to investigate the suitability of using impedance analysis and optical emission spectroscopy (OES) for real-time plasma process monitoring. It is assumed that plasma system is a equivalent circuit. Therefore, V-I probe is used for measuring impedance, which can be a new non-intrusive probe for plasma diagnosis. From impedance data, we tried to analyse physical properties of plasma. And OES, the other method of plasma diagnosis, is a typical non-intrusive probe for analyzing chemical properties. The amount of the OES data is typically large, so this poses a difficulty in extracting relevant information. To solve this problem, principal component analysis (PCA) can be used. For fundamental information, Ar plasma and $O_2$ plasma are used in this experiment. This method can be applied to real-time endpoint and fault detections.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.3
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• pp.196-200
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• 2009

Lithium niobate ($LN:LiNbO_3$) is a compound of niobium, lithium and oxygen. The characteristics of LN are piezoelectricity, ferroelectricity and photoelectricity, and which is widely used in surface acoustic wave (SAW). To manufacture LN devices, the LN surface should be a smooth surface and defect-free because of optical property, but the LN material is processed difficult b traditional processes such as grinding and mechanical polishing (MP) because of its brittleness. To decrease defects, chemical mechanical polishing (CMP) was applied to the LN wafer. In this study, the suitable parameters such as down force and relative velocity, were investigated for the LN CMP process To improve roughness, the LN CMP was performed using the parameters that were the highest removal rate among process parameters. And, evaluation of optical property was performed by the optical reflectance.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.2
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• pp.105-107
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• 2002

a-C:H films were coated on windows of mobile telephone by RF plasma chemical vapor deposition equipment made in our company. Thickness of the coatings is about 0.7 micrometers and they have high hardness, low friction coefficient, good adhesion, high optical transparency and chemical inertness. Knoop hardness of the diamond-like carbon films on glass substrate is 2328 kg/mm$^2$. The adherence between films and substrate is good and shows to be 69 N by scratching test. The optical performance is improved obviously owing to coat the film on it. The index of the coated windows is 2.5, transmission of visible light is larger than 90%, and transmission of ultraviolet light decreases by 30% and the ultraviolet light can be obstructed obviously. The coated glass also has self-clean effect and decontamination ability. The films have hydrophobic character and the soakage angle of water drop is larger than 90 degrees. The windows have fog-proof ability owing to eliminate the capillary phenomena in the inner surface. The physics and chemical properties of the coated windows are steady. Study indicates that the performance of a-C:H coated mobile phone windows are improved notably on wear-resistance, corrosion-proof and optical properties and it is excellent mobile windows protective coatings.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.220-221
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• 1999

Single crystals of Yttrium Calcium Oxyborate (YCOB) doped with different concentrations of Er3+ and Yb3+ ions were growth by Czochralski method. High qualities of crystals in morphology and transparency were obtained . Analysis on crystal structure and lattice parameters were performed by X-ray diffraction method. It was found that congruent melting composition is YCA4.2O1.2(BO3)3. Absorption and fluorescence properties of grown crystals were also reported.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1601-1602
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• 2014

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.259-266
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• 2019

Tuning of electro-optical properties of nano-structured $SnO_2:Ga$ powders in a micro drop fluidized reactor (MDFR) was highly effective to enhance the activities of powders to be used as sensor materials. The tuning was conducted continuously in a facile one-step process during the formation of powders. The microscopic hydrodynamic forces affected the band gap structure and charge transfer of $SnO_2:Ga$ powders through the oxygen and interfacial tin vacancies by providing plausible pyro-hydraulic conditions, which resulted in the decrease in the electrical resistance of the materials. The analyses of room-temperature photoluminescence (PL) spectra and FT-IR exhibited that the tuning could improve the surface activities of $SnO_2:Ga$ powders by adjusting the excitation as well as separation of electrons and holes, thus maximizing the oxygen vacancies at the surface of the powders. The scheme of photocatalytic mechanism of $SnO_2:Ga$ powders was also discussed.

• Journal of Astronomy and Space Sciences
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• v.11 no.2
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• pp.165-174
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• 1994

We have investigated the chemical composition of dust grains in novae by computing the model spectra for the novae that showed temporary infrared developments shortly after their optical explosions. We find that a simple spherical dust shell models with hot blackbody central sources fit observations fairly well. Optical properties of dust grains deduced from modeling of AGB stars have been used for present calculations. We find that amorphous carbon grains appear to be the major infrared re-emission sources for the carbon-rich nova shells, and the silicate grains for the oxygen-rich nova shells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1091-1096
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• 2003

Ion implantation in polymeric materials can induce dramatic chemical modifications, such as bond breaking, cross linking, formation of new chemical products, which have strong influences on the macroscopic properties of the materials. In this study ion implantation was performed onto polymer, PC(polycarbonate), in order to investigate change of the optical transmittance property focusing ultraviolet ray range(200-400nm). PC was irradiated with N, Ar, Kr, Xe ions at the ion energy of 50keV and the dose range of 5 ${\times}$ 10$\^$15/, 1 ${\times}$ 10$\^$16/, 7${\times}$10$\^$16/ ions/$\textrm{cm}^2$. FT-IR, XPS, UV/Vis transmittance spectroscopy measurement technologies were employed to obtain chemical. structural properties and optical transmittance of irradiated polymer. The original PC(unimplanted) is quite transparent that it has more than 88% transmittance in the range UV-A(320∼400nm), but after ion implantation, surface colors were changed to the dark brown and the transmittance of UV ray decreased for all implantation condition, and the absorption edge was shift to visible range with increasing mass of implanted ion species and dose.

• Journal of the Korean Ceramic Society
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• v.54 no.6
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• pp.484-491
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• 2017

Chalcogenide glasses have been investigated in their thermodynamic, structural, and optical properties for application in various opto-electronic devices. In this study, the $Sb_{20}Se_{80-x}Ge_x$ with x = 10, 15, 20, and 25 were selected to investigate the glass stability according to germanium ratios. The thermal, structural, and optical properties of these glasses were measured by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and UV-Vis-IR Spectrophotometry, respectively. The DSC results revealed that $Ge_{20}Sb_{20}Se_{60}$ composition showing the best glass stability theoretically results due to a lower glass transition activation energy of 230 kJ/mol and higher crystallization activation energy of 260 kJ/mol. The structural and optical analyses of annealed thin films were carried out. The XRD analysis reveals obvious results associated with glass stabilities. The values of slope U, derived from optical analysis, offered information on the atomic and electronic configuration in Urbach tails, associated with the glass stability.