• Korean Journal of Remote Sensing
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• v.6 no.1
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• pp.49-62
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• 1990

The study is aimed to analize the spectral characteristics of igneous and sedimentary rocks in their reflectance curves obtained from CARY 17-D Spectrophotometer, and correlation between chemical complsition and HHRR data. The reflectance is higher in acidic igneous rocks, while lower in basic igneous rocks. Especially acidic plutonic rocks show sharp absorption bands at 1.4 and 1.9 $\mu\textrm{m}$ due to water inclusion in felsic minerals and basic rocks a broad absoption band near 1.mu.m due to Fe$^{++}$ ion in mafic minerals. Sandstones generally have higher reflectance than siltstones and shales, and show strong absorption at 1.4 and 1.9 $\mu\textrm{m}$. Arkosic sandstones have lower reflectance at blue band due to Fe$^{+++}$ ion exsolved from feldspars. The HHRR data have a positive correlation with SiO$_2$ and $K_2$O, while they have a negative correlation with FeO and MgO.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1199-1205
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• 2006

This paper proposes a wideband monopole antenna with improved band rejection characteristics by inserting two band notch slots with half wavelength in radiator. The designed antenna is composed of bow-tie patch fed electromagnetically with parasitic ground patch of a semicircular shape. We obtained band rejection filter-like characteristics by controlling coupling amounts between two horizontal resonance slots. Using this technique, we achieved the broad rejection bandwidth and improved skirt characteristics compared with only one notch slot. The measured bandwidth is from 2.7 GHz to 6.9 GHz for VSWR below 2.0 except the limited band of $4.96{\sim}5.51GHz$. This antenna shows a similar radiation pattern of the ideal monopole and the radiation gain reduction is more than $5{\sim}10dB$ on the x-z plane at rejection frequency.

• Journal of Navigation and Port Research
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• v.30 no.9
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• pp.763-766
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• 2006

In this paper, the EM wave absorbers were designed and fabricated for X -band sensors using Carbon of dielectric material with CPE. The complex relative permittivity of samples is calculated by using measurement results of S-parameter. We simulated the double-layered type EM wave absorber with broad bandwidth using the measured complex relative permittivity by changing the thickness and layer, which was fabricated based on the simulated design The fabricated EM wave absorber consists of 1 mm first layer sheet facing metal with Carbon composition ratio 70 vol. % and 1.5 mm second layer sheet with Carbon composition ratio 60 vol. %. The measured results showed a good agreement to the simulated ones. It is found toot the optimized absorption ability of double-layered type EM wave absorber with thickness of 2.5 mm is higher than 10 dB from 7.8 GHz to 13.3 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.351-356
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• 2009

A dual-mode annular ring antenna for both global positioning system(GPS) and satellite digital multimedia broad-casting(DMB) is designed. The proposed antenna consists of a coupling feed line and four slots on the annular ring patch. The gap between the feed line and the annular ring patch is used for an input impedance matching, and the slot length is used for adjusting the resonant frequency of the $TM_{21}$ mode at the DMB frequency. The antenna was fabricated and measured. The experimental results show that the antenna resonants at the GPS and DMB frequencies with suitable bandwidths, and had a broadside radiation pattern at the GPS band and a conical beam radiation pattern at the DMB band.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.187-190
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• 2005

The Cosmic Evolution Survey (COSMOS) is a Hubble Space Telescope (HST) treasury project. The COSMOS aims to perform a 2 square degree imaging survey of an equatorial field in I(F814W) band, using the Advanced Camera for Surveys (ACS). Such a wide field survey, combined with ground-based photometric and spectroscopic data, is essential to understand the interplay between large scale structure, evolution and formation of galaxies and dark matter. In 2004, we have obtained high-quality, broad band images of the COSMOS field (B, V, r', i', and z') using Suprime-Cam on the Subaru Telescope, and we have started our new optical multi-band program, COSMOS-21 in 2005. Here, we present a brief summary of the current status of the COSMOS project together with contributions from the Subaru Telescope. Our future Subaru program, COSMOS-21, is also discussed briefly.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1973-1976
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• 2008

Electronic photodepletion spectrum of dibenzo-18-crown-6 with a potassium ion ($K^+$-DB18C6) was obtained in the gas phase using electrospray ionization and quadrupole ion-trap reflectron time-of-flight mass spectrometry. The spectrum exhibited rather a broad absorption band at 36350 $cm^{-1}$, which was tentatively assigned as the origin of the S1 band. The photodepletion spectrum of $Cs^+$-DB18C6 was also obtained to elaborate the effects of metal cations on electronic and geometric structures of metal cation-DB18C6 complexes. We found that the S1 band of $Cs^+$-DB18C6 was red-shifted by 180 $cm^{-1}$ from that of $K^+$-DB18C6. With the results of quantum theoretical calculations using the density functional theory, we suggested that the red-shift arose mainly from weaker binding of $Cs^+$ to DB18C6 than that of K+, which resulted from a larger size of $Cs^+$ than that of the cavity in DB18C6.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.57.1-57.1
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• 2016

Methanol ($CH_3OH$) is a key species in the formation of complex organic molecules. We report the first detection of solid $CH_3OH$ in a line of sight toward the Galactic center (GC) region, based on L-band spectra taken with the Subaru telescope, aided by L'-band imaging data and moderate-resolution spectra from NASA/IRTF. It is found toward a background star, ~8000 AU in projected distance from a newly discovered massive young stellar object (YSO). This YSO also exhibits a strong $CO_2$ ice absorption band at ${\sim}15{\mu}m$ in Spitzer/IRS data, which has a prominent long-wavelength wing. It confirms that a high $CH_3OH$ abundance is responsible for the broad $15{\mu}m$ $CO_2$ ice absorption towards massive YSOs in the GC. Clearly, $CH_3OH$ formation in ices is efficient in the GC region, as it is in star-forming regions in the Galactic disk. We discuss implications of our result on the astrochemical processes in the hostile GC molecular clouds.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1183-1187
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• 2005

In this paper, a weathercock-shaped microstrip patch antenna for application in 5.25GHz band wireless LAN is designed and fabricated. To obtain sufficient bandwidth in VSWR<2, the T-slot is inserted on the patch, the coaxial probe source is used. The measured result of fabricated antenna obtained 350MHz or about $7.62\%$ bandwidth in VSWR<2 referenced to the center frequency, the gain of 5.25${\~}$6.70dBi. The experimental 3-dB beam width is shown to be broad across the pass band in azimuth and elevation at $80.32^{\circ}$ and $83.88^{\circ}$, in several.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.73.1-73.1
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• 2017

Reverberation mapping is one of the best way to investigate structure and kinematics of broad-line regions around central supermassive black holes of active galactic nuclei (AGN). It is usually used to estimate masses of supermassive black holes. So far, reverberation mapping studies have achieved good results for dozens of AGN by spectroscopic monitoring. However, spectroscopic monitoring is time consuming and high cost. Here, we present result of photometric reverberation mapping with medium-band observation. We monitored five nearby AGN which are already studied, have short time-lag, and show bright H-alpha emission lines. Observation has been performed for ~3 months with ~3 days cadence using three medium-band filters installed in LSGT (Lee Sang Gak Telescope). We found 0.01-0.06 magnitude variations by differential photometry. Also time-lags between continuum light-curves and H-alpha emission line light-curves are calculated using Javelin software. The result shows that our study and previous studies are consistent within uncertainty range. From verification of availability in this study, photometric reverberation mapping could be used as a powerful tool to measure central supermassive black holes for large samples and high-redshift AGN in the future.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.2
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• pp.53-63
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• 2016

Monitoring of cyanobacteria bloom in reservoir systems is important for water managers responsible of water supply system. Cyanobacteria affect the taste and smell of water and pose considerable filtration problems at water use places. Harmful cyanobacteria bloom in reservoir have significant economic impacts. We develop a new method for estimating the cyanobacteria bloom using Landsat TM and ETM+ data. Developed model was calibrated and cross-validated with existing in situ measurements from Daecheong Reservoir's Water Quality Monitoring Program and Algae Alarm System. Measurements data of three stations taken from 2004 to 2012 were matched with radiometrically converted reflectance data from the Landsat TM and ETM+ sensor. Stepwise multiple linear regression was used to select wavelengths in the Landsat TM and ETM+ bands 1, 2 and 4 that were most significant for predicting cyanobacteria cell number and bio-volume. Based on statistical analysis, the linear models were that included visible band ratios slightly outperformed single band models. The final monitoring models captured the extents of cyanobacteria blooms throughout the 2004-2012 study period. The results serve as an added broad area monitoring tool for water resource managers and present new insight into the initiation and propagation of cyanobacteria blooms in Daecheong reservoir.