• Journal of the Korean earth science society
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• v.30 no.3
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• pp.344-353
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• 2009

By measuring the brightness of night sky, we have investigated light pollution around the observatory in the College of Education, Seoul National University. As a result of measuring the extinction coefficient and photometric constants by standardization, in January 28, 2009, the extinction coefficient found to be $k_B$=0.359 and photometric constant was $C_B$=4.397. In March 27, 2009, extinction coefficients were $k_B$=0.896 and $k_V$=0.725, and photometric constants were $C_B$=6.235 and $C_V$=6.027. Brightness of the night sky was measured from east, west, south, and north each by altitude of $20^{\circ}$, $40^{\circ}$, $60^{\circ}$, $75^{\circ}$ and $90^{\circ}$. Data reduction and analysis was based on IRAF. Seeings for the each day of observation were 5.1 and 5.7 arcseconds in January 28 and March 27, respectively. Night sky spanned the magnitude range of $16{\leq}m_V$, $m_B{\leq}18$ We found that the brightness of night sky located at downtown was twice to four times brighter. On these observational conditions, limiting magnitude within 40cm-telescope becomes 11-13 magnitudes. Compared with Jan 28 and Mar 27, night sky brightness of January is 1 magnitude fainter than that of March in B filter.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.267-272
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• 2005

We deposited thin films of organic light-emitting-material $Alq_3$(alumina quinoline) on silicon and slide-glass substrates using thermal evaporation method, and measured spectra of ellipsometry angles ${\Delta}$ and ${\Psi}$ in the photon-energy range of 1.5~5.0 eV using a variable angle spectroscopic ellipsometer. The optical constants, refractive index and extinction coefficient, of $Alq_3$ were determined via the dispersion parameters extracted from the curve-fitting process based on Jellison-Modine dispersion function. The reliability of determined optical constants were verified through the comparison of measured and simulated transmittance curves and the good agreement between simulated absorption-coefficient curves and absorbance spectra measured using a spectrophotometer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.1
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• pp.73-79
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• 2013

Crystalline silicon solar cells with $SiN_x/SiN_x$ and $SiN_x/SiO_x$ double layer anti-reflection coatings(ARC) were studied in this paper. Optimizing passivation effect and optical properties of $SiN_x$ and $SiO_x$ layer deposited by PECVD was performed prior to double layer application. When the refractive index (n) of silicon nitride was varied in range of 1.9~2.3, silicon wafer deposited with silicon nitride layer of 80 nm thickness and n= 2.2 showed the effective lifetime of $1,370{\mu}m$. Silicon nitride with n= 1.9 had the smallest extinction coefficient among these conditions. Silicon oxide layer with 110 nm thickness and n= 1.46 showed the extinction coefficient spectrum near to zero in the 300~1,100 nm region, similar to silicon nitride with n= 1.9. Thus silicon nitride with n= 1.9 and silicon oxide with n= 1.46 would be proper as the upper ARC layer with low extinction coefficient, and silicon nitride with n=2.2 as the lower layer with good passivation effect. As a result, the double layer AR coated silicon wafer showed lower surface reflection and so more light absorption, compared with $SiN_x$ single layer. With the completed solar cell with $SiN_x/SiN_x$ of n= 2.2/1.9 and $SiN_x/SiO_x$ of n= 2.2/1.46, the electrical characteristics was improved as ${\Delta}V_{oc}$= 3.7 mV, ${\Delta}_{sc}=0.11mA/cm^2$ and ${\Delta}V_{oc}$=5.2 mV, ${\Delta}J_{sc}=0.23mA/cm^2$, respectively. It led to the efficiency improvement as 0.1% and 0.23%.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.32-32
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• 2017

To increase rice production, manipulating plant architecture, especially developing new high-yielding cultivars with erect leaves, is crucial in rice breeding programs. Leaf inclination angle determines the light extinction coefficient (k) of the canopy. Erect leaves increase light penetration into the canopy and enable dense plantings with a high leaf area index, thus increasing biomass production and grain yield. Because of erect leaves, the high-yielding indica rice cultivar 'Takanari' has smaller k during ripening than 'Koshihikari', a japonica cultivar with good eating quality. In our previous study, using chromosome segment substitution lines (CSSLs) derived from a cross between 'Takanari' and 'Koshihikari', we detected seven quantitative trait loci (QTLs) for leaf inclination angle on chromosomes 1 (two QTLs), 2, 3, 4, 7, and 12. In this study, we developed a near-isogenic line (NIL-3) carrying a 'Takanari' allele for increased leaf inclination angle on chromosome 3 in the 'Koshihikari' genetic background. We compared k, dry matter production, and grain yield of NIL-3 with those of 'Koshihikari' in the field from 2013 to 2016. NIL-3 had higher inclination angles of the flag, second, and third leaves at full heading and 3 (- 4) weeks after full heading and smaller k of the canopy at the ripening stage. Biomass at full heading and leaf area index at full heading and at harvest did not significantly differ between NIL-3 and 'Koshihikari'. However, biomass at harvest was significantly greater in NIL-3 than in 'Koshihikari' due to a higher net assimilation rate at the ripening stage. The photosynthetic rates of the flag and third leaves did not differ between NIL-3 and Koshihikari at ripening. Grain yield was higher in NIL-3 than 'Koshihikari'. Higher panicle number per square meter in NIL-3 contributed to the higher grain yield of NIL-3. We conclude that the QTL on chromosome 3 increases dry matter and grain production in rice by increasing leaf inclination angle.

• Textile Coloration and Finishing
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• v.9 no.3
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• pp.10-17
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• 1997

The study was performed to obtain the optimum extraction conditions for crocin from gardenia fructus. Generally crocin is unstable on heat, light, acid and base solution. The extraction efficiency of crocin from gardenia depended upon the extraction time, extraction temperature, pH in the extraction bath and the optimum conditions of crocin extraction were determined as 60 minutes of extraction time, 4$0^{\circ}C$ of extraction temperature, pH 7 of extraction bath. The molar extinction coefficient of crocin was 12,515 and the color yield of purified crocin was about six times higher than that of non-purified crocin. The heat-stability at extraction temperature and lightstability in irradiation with xenon lamp for one hour of the purified crocin were higher than those of non-purified crocin. Intensity of &{\lambda}_{max}&of crocin was decreased by irradiation for one hour but UV-Vis. spectra of crocin was not changed. The colors of purified and non-purified crocin dissolved wit methanol was evaluated by means of CIE L* a* b* system.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.119.2-119.2
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• 2011

Dye-sensitized solar cells (DSSC) are currently attracting wide spread academic and commercial interest for the conversion of sunlight into electricity because of their easy manufacturing process and high efficiency. The solar energy conversion efficiencies of DSSC are strongly dependent on dye molecules adsorbed on the TiO2 surface which used for photosensitization of sun light, since an excited state of dye could inject an electron into the conduction band of semiconductor. We have developed novel organic dyes which have phenothiazine moieties as an electron donor in their charge-transfer chromophore for application of DSSCs. We had synthesized a series of phenothiazine derivatives which have different wave length absorbing chromophore in the molecule with high molar extinction coefficient. The photovoltaic performance of DSSC composed of organic chromophores with broad wavelength absorption property were measured and evaluated by comparison with that of pristine ruthenium dye.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.198-198
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• 2010

The low-k SiOCH thin films were prepared by CCP-PECVD method using BTMSM(Bis-trimethylsilylmethane) precursors deposited on p-Si wafer. The structural complexity originate the complex refractive constants of the films, and resulted the elliptical polarization of the incident linearly polarized light source of Xe-ramp in the range from 190nm to 2100nm. Phase difference and amplitude ratio between s wave and p wave propagating through SiOCH thin film was studied. After annealing, the amplitude of p wave was reduced more than s wave, and phase difference between p and s wave was also reduced.

• Journal of Digital Contents Society
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• v.10 no.2
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• pp.299-307
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• 2009

It is well-known that the scenic visibility achieved in our naked eyes is related with the quality of aerosol condition which is composed of primary and secondary air pollutants. In recent, the IMPROVE organization in U.S.A. has developed two algorithms to estimate the visible length depending on the elements of air pollutant. Using these algorithms, we are to represent the condition of aerosol quality with the well-known scenic images of the observing area so that any one that have no sufficient chemical knowledge may feel and understand the level of air pollution in visuality.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.228-233
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• 2010

We studied the optical characteristics correlated with low dielectric constants of low-k SiOCH thin films through ellipsometry. The low-k SiOCH thin films were prepared by CCP-PECVD method using BTMSM(Bis-trimethylsilylmethane) precursors deposited on p-Si wafer. The Si-O-CHx, Si-O-Si, Si-CHx, CHx and Si-H bonding groups were specified by FTIR spectroscopic spectra, and the groups coupled with the nano-porous structural organic/inorganic hybrid-type of SiOCH thin films which has extremely low dielectric constant close to 2.0. The structural groups includes highly dense pore as well as ions in SiOCH thin films affecting to complex refraction characteristics of single layer on the p-Si wafer. The structural complexity originate the complex refractive constants of the films, and resulted the elliptical polarization of the incident linearly polarized light source of Xe-light source in the range from 190 nm to 2100 nm. Phase difference and amplitude ratio between s wave and p wave propagating through SiOCH thin film was studied. After annealing, the amplitude of p wave was reduced more than s wave, and phase difference between p and s wave was also reduced.

• Journal of the Optical Society of Korea
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• v.15 no.1
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• pp.96-102
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• 2011

Simultaneous measurements using a scanning spectrograph system and transmissometer were performed for the first time over an urban site in Gwangju, Korea, to derive the ambient $NO_2$ volume mixing ratio. The differential slant column densities retrieved from the scanning spectrograph system were converted to volume mixing ratios using the light traveling distance along the scanning line of sight derived from the transmissometer light extinction coefficients. To assess the performance of this system, we compared the derived $NO_2$ volume mixing ratios with those measured by an in situ chemiluminescence monitor under various atmospheric conditions. For a cloudless atmosphere, the linear correlation coefficient (R) between the two data sets (i.e., data derived from the scanning spectrograph and from the in situ monitor) was 0.81; the value for a cloudy atmosphere was 0.69. The two sets of $NO_2$ volume mixing ratios were also compared for various wind speeds. We also consider the measurement errors, as estimated from an error propagation analysis.