• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.42-45
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• 1992

The poly silicon thin films were prepared by solid phase crystallization at 600$^{\circ}C$ of amorphous silicon films deposited on Corning 7059 glass and (100) silicon wafer with thermally grown SiO$_2$substrate by plasma enhanced chemical vapor deposition with varying rf power, deposition temperature, total flow rate. Crystallization time, microstructure, absorption coefficients were investigated by RAMAN, XRD analysis and UV transmittance measurement. Crystallization time of amorphous silicon films was increased with increasing rf power, decreasing deposition temperature and decreasing total flow rate.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.451-457
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• 2006

The purpose of this study is to measure fundamental data required for the prediction of rice quality and to develop regression models to predict protein, amylose, moisture and fatty acid contents, and Toyo taste meter value (TTMV) of brown and polished rice from hulled rice NIR spectra. NIR spectra of hulled rice measured in transmittance mode (850-1050 nm) and in reflectance mode (400-2500 nm) were used to predicted chemical compositions of brown rice and polished rice. For most chemicals, the transmittance spectra could provide better calibration results than the reflectance ones. Beside the Toyo taste meter value (TTMV), the hulled rice spectra could predict chemical contents with the determination coefficients higher than 0.8. Spectra of hulled rice measured in transmittance mode could be used for the prediction of chemical compositions in brown rice and polished rice precisely. However, taste value of polished rice was a constituent that was hardly to be predicted.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.176-177
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• 2013

Surface plasmon polaritons (SPPs) have attracted the attention of scientists and engineers involved in a wide area of research, microscopy, diagnostics and sensing. SPPs are waves that propagate along the surface of a conductor, usually metals. These are essentially light waves that are trapped on the surface because of their interaction with the free electrons of conductor. In this interaction, the free electrons respond collectively by oscillating in resonance with the light wave. The resonant interaction between the surface charge oscillation and the electromagnetic field of the light constitutes the SPPs and gives rise to its unique properties. In this papers, we studied theoretical and experimental extraordinary transmittance (T) and reflectance (R) of 2 dimensional metal hole array (2D-MHA) on GaAs in consideration of the diffraction orders. The 2d-MHAs was fabricated using ultra-violet photolithography, electron-beam evaporation and standard lift-off process with pitches ranging from 1.8 to $3.2{\mu}m$ and diameter of half of pitch, and was deposited 5-nm thick layer of titanium (Ti) as an adhesion layer and 50-nm thick layer of gold (Au) on the semiinsulating GaAs substrate. We employed both the commercial software (CST Microwave Studio: Computer Simulation Technology GmbH, Darmstadt, Germany) based on a finite integration technique (FIT) and a rigorous coupled wave analysis (RCWA) to calculate transmittance and reflectance. The transmittance was measured at a normal incident, and the reflectance was measured at variable incident angle of range between $30^{\circ}{\sim}80^{\circ}$ with a Nicolet Fourier transmission infrared (FTIR) spectrometer with a KBr beam splitter and a MCT detector. For MHAs of pitch (P), the peaks ${\lambda}$ max in the normal incidence transmittance spectra can be indentified approximately from SP dispersion relation, that is frequency-dependent SP wave vector (ksp). Shown in Fig. 1 is the transmission of P=2.2 um sample at normal incidence. We attribute the observation to be a result of FTIR system may be able to collect the transmitted light with higher diffraction order than 0th order. This is confirmed by calculations: for the MHAs, diffraction efficiency in (0, 0) diffracted orders is lower than in the (${\pm}x$, ${\pm}y$) diffracted orders. To further investigate the result, we calculated the angular dependent transmission of P=2.2 um sample (Fig. 2). The incident angle varies from 30o to 70o with a 10o increment. We also found the splitting character on reflectance measurement. The splitting effect is considered a results of SPPs assisted diffraction process by oblique incidence.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.436-442
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• 2014

In this study, we developed an optical-fiber sensor using cobalt chloride solution to monitor temperature in real-time between long distance points unaffected by the electro-magnetic wave and the vibration. Cobalt chloride solutions were made using 10% water and 90% ethanol (v/v) solution. The transmittance of these solutions was analyzed on 655 nm using UV-Visible spectrometer regarding temperature change. Also 30.8 mM cobalt chloride solution was gelled by dissolving polyvinyl butyral and the transmittance of this was analyzed on 655 nm regarding temperature change. The results of transmittance and optical power measurement showed decrease of both transmittance and optical power with increase of temperature from 66.8% and 149.5 nW at $25^{\circ}C$ to 7.1% and 48 nW at $70^{\circ}C$, respectively. These results support the possibility of gelled cobalt chloride/polyvinyl butyral as an optical-fiber sensor to monitor temperature change.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.191-194
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• 2002

In optical pick-up, optical components such as objective lens, collimator, mirror, laser diode and photo diode are mounted on the pick-up base. These components must keep their original position during operation for proper transmittance of information from laser diode to optical disk and back to photo diode. However, micro thermal deformation of pick-up base which is induced by thermal environment during operation can deteriorate the performance of optical pick-up. Therefore, it is important to measure and analyze the thermal deformation behavior of pick-up base under thermal environment. In the present study, a measurement system using holographic interferometry was designed to measure micro thermal deformation of pick up base. The measurement system was verified by using the deformation of cantilever with prescribed motion actuated by PZT with 1 nm resolution. Interferometric measurement was compared quantitatively with that induced by PZT actuator. Finally, micro thermal deformation of pick-up base under actual thermal environment was measured using the present holographic interferometry and the results were analysed.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.312-312
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• 2013

GaN based light emitting diodes (LEDs) are important devices that are being used extensively in our daily life. For example, these devices are used in traffic light lamps, outdoor full-color displays and backlight of liquid crystal display panels. To realize high-brightness GaN based LEDs for solid-state lighting applications, the development of p-type ohmic electrodes that have low contact resistivity, high optical transmittance and high refractive index is essential. To this effect, indiumtin oxide (ITO) have been investigated for LEDs. Among the transparent electrodes for LEDs, ITO has been one of the promising electrodes on p-GaN layers owing to its excellent properties in optical, electrical conductivity, substrate adhesion, hardness, and chemical inertness. Sputtering and e-beam evaporation techniques are the most commonly used deposition methods. Commonly, ITO films on p-GaN by sputtering have better transmittance and resistivity than ITO films on p-GaN by e-bam evaporation. However, ITO films on p-GaN by sputtering have higher specific contact resistance, it has been demonstrated that this is due to possible plasma damage on the p-GaN in the sputtering process. In this paper, we have investigated the advanced sputtering using plasma damage-free p-electrode. Prepared the ITO films on the GaN based LEDs by e-beam evaporation, normal sputtering and advanced sputtering. The ITO films on GaN based LEDs by sputtering showed better transmittance and sheets resistance than ITO films on the GaN based LEDs by e-beam evaporation. Finally, fabricated of GaN based LEDs by using advanced sputtering. And compared the electrical properties (measurement by using C-TLM) and structural properties (HR-TEM and FE-SEM) of ITO films on GaN based LEDs produced by e-beam evaporation, normal sputtering and advanced sputtering. As a result, It is expected to form plasma damage free-electrode, and better light output power and break down voltage than LEDs by e-beam evaporation and normal sputter.

• Journal of the Korean Society of Tobacco Science
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• v.28 no.2
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• pp.111-116
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• 2006

It is very important to add uniformly casing materials on tobacco for taste and flavor. However, analysis of casing materials was spent much time, effort and money. The object of this study was the development of a rapid method for the determination of glycerine, propylene glycol(PG), sucrose, glucose, fructose and water in the casing materials using the NIR transmittance method. Hundreds of calibration samples, with extended ranges (50%, 75%, 100%, 125%, and 150% of standard addition) in each constituent, were prepared in the casing materials at the various temperatures $(25^{\circ}C\;and\;30^{\circ}C)$. Calibration equation was developed by modified partial least square (MPLS) method using second derivative. The standard error of calibration and $R^2$ between added value and NIR estimated value results were $0.007{\sim}0.034\;and\;0.996{\sim}1.000$ for the casing sample set, respectively. The standard error of prediction and R2 between added value and NIR estimated value results were $0.010{\sim}0.034\;and\;0.997{\sim}1.000$ for the casing sample set, respectively. The analysis result was not different significantly between the NIR and added value. These results show that the NIR measurement system is an effective tool to ensure quality on the casing materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.316-316
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• 2008

Using an evaporation method, $SiO_2$ was deposited as a buffer layer between a flexible PET substrate and a ITO film deposited by DC magnetron sputtering and electro-optical properties were investigated with thickness variance of $SiO_2$ layers. After coating a $SiO_2$ layer and a ITO film, the ITO/$SiO_2$/PET was heated up to $200^{\circ}C$ and the resistivity and the transmittance were measured by hall effect measurement system and UV/VIS/NIR spectroscopy. As a result of depositing a $SiO_2$ buffer layer, the resistivity increased and the transmittance and adhesion property were enhanced than ITO films with no buffer layers and the resistivity was lowered as $SiO_2$ thickness increased from 50 $\AA$ to 100 $\AA$. It was found that the transmittance was independent of annealing temperature variance in $150^{\circ}C{\sim}200^{\circ}C$ and the resistivity decreased as the temperature increased and especially decreasing rate of the resistivity was higher as the buffer layer thickness was thinner. So under optimized depositing of $SiO_2$ buffer layers and post-annealing of ITO/$SiO_2$/PET, ITO films with enhanced adhesion, electro-optical properties can obtained.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.314-320
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• 2014

Three leaf vegetables, namely green lettuce, red lettuce (Lactuca sativa) and red-veined chicory (Cichorium intybus) were grown in minigreenhouses covered with two new functional films and conventional polyethylene film (PE). Seedlings of leaf vegetables were transplanted in a plastic troughs filled with soil-perlite mixture. Two functional films were made from polyolefin (PO) material. Measurement of optical characteristics showed that polyolefin films have better transmittance for the photosynthetic active radiation (PAR, 400-700nm) and higher absorptance for the ultraviolet radiation (UV, 300-400nm) in comparison with the conventional PE film. After three months of utilization higher loss in PAR transmittance was observed for conventional PE film. Leaf vegetables growth was enhanced and yield was increased in greenhouses covered by new functional films.

• Korean Journal of Materials Research
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• v.15 no.8
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• pp.518-520
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• 2005

Effects of the $O_2/Ar$ flow ratio in the sputtering process on the crystallinity, surface roughness, carrier concentration, carrier mobility, and optical properties of Al-doped ZnO thin films deposited on sapphire (001) substrates by RF magnetron sputtering were investigated. XRD spectra showed a preferred orientation along the c-axis and a minimum FWHM of the (002) XRD intensity peak for the $O_2/Ar$ flow ratio of 0.5. The (101)peak also appeared and the degree of preferred orientation decreased as the $O_2/Ar$ flow ratio increased from 0.5 to 1.0. AFM analysis results showed that the surface roughness was lowest at the $O_2/Ar$ flow ratio of 0.5 and tended to increase owing to the increase of the grain size as the $O_2/Ar$ flow ratio increased further. According to the Hall measurement results the carrier concentration and carrier mobility of the fan decreased and thus the resistivity increased as the $O_2/Ar$ flow ratio increased. The transmittance of the ZnO:Al film deposited on the glass substrate was characteristic of a standing wave. The transmittance increased as the $O_2/Ar$ flow ratio in-RF magnetron sputtering increased up to 0.5. Considering the effects of the $O_2/Ar$ flow ratio on the surface roughness, electrical resistivity and transmittance properties of the ZnO:Al film the optimum $O_2/Ar$ flow ratio was 0.5 in the RF magnetron sputter deposition of the ZnO:Al film.