• 천문학회지
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• 제29권2호
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• pp.255-268
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• 1996

We present VR CCD photometry and long-slit spectroscopy of a late type spiral galaxy NGC 7678. The grey scale images and isophotal maps illustrate the presence of a weak bar from which spiral arms emerge. There are many HII regions along the spiral arms, but bright giant HII regions are more concentrated in the massive southern arm. The bright compact nucleus of NGC 7678 is bluer than bulge and bar. The spectral features of the nucleus and HII regoins are very similar but the nuclear spectra shows higher $[NII]{\lambda}6583/H_\alpha$ than those of the HII regions. The nucleus of NGC 7678 seems to be intermediate type between HII region nulcei and LINERs by the ratio of $[NII]{\lambda}6583/H_\alpha$, but it is more likely to be HII region-like nucleus if we consider the $[NII]{\lambda}6716,6731/H_\alpha$ together. The star formation rate is estimated to be about $0.2 M_\bigodot\;yr^{-1}$ based on the $H_\alpha$ flux.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권11호
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• pp.634-643
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• 2003

This paper presents a method for detecting skin tumors on chicken carcasses using hyperspectral images. It utilizes both fluorescence and reflectance image information in hyperspectral images. A detection system that is built on this concept can increase detection rate and reduce processing time, because the procedure for detection can be simplified. Chicken carcasses are examined first using band ratio FCM information of fluorescence image and it results in candidate regions for skin tumor. Next classifier selects the real tumor spots using PCA components information of reflectance image from the candidate regions. For the real world application, real-time processing is a key issue in implementation and the proposed method can accommodate the requirement by using a limited number of features to maintain the low computational complexity. Nevertheless, it shows favorable results and, in addition, uncovers meaningful spectral bands for detecting tumors using hyperspectral image. The method and findings can be employed in implementing customized chicken tumor detection systems.

• Journal of the Optical Society of Korea
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• 제20권3호
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• pp.435-440
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• 2016

We developed a simple and real-time readout autocorrelator for several tens and sub-10fs pulses, based on the two photon absorption phenomena of a commercial GaP photodetector including a transimpedance amplifier. With a suitable gain adjustment, we demonstrated that the interferometric autocorrelation for sub-nJ pulses delivered as a high output voltage as to resolve all fringes in an autocorrelation trace with features of low noise and a low offset voltage. By fitting the measured quadratic power dependence of output voltages, we obtained the quantum efficiency of TPA for the GaP detector comparable with those of a GaAsP diode and an SHG with a thin BBO crystal. The autocorrelator of a TPA based GaP photodetector is highly suitable for sensitively measuring a few cycle pulses with a broad spectral distribution from 600 nm to 1100 nm.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.558-563
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• 2014

Sum-frequency generation spectra of a Langmuir monolayer on water surface at varying surface areas were studied with two-dimensional correlation analysis. Upon enlarging the area/molecule of the Langmuir monolayer, the sum-frequency spectra changed reflecting the conformation change of the alkyl chains of the molecules in the monolayer. These changes stood out more clearly by employing two-dimensional correlation analysis of the above sum-frequency spectra. Features not very pronounced in the original spectra such as closely-spaced spectral bands can also be easily distinguished in the two-dimensional correlation spectra.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1111-1115
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• 2002

The photoluminescence of calixarene crystals has been studied as functions of temperature, time, and concentration. The vibronic bands shift to longer wavelength and become significantly sharper as temperature decreases. The experimental results r eveal that the structural transformation occur during the annealing process. Time-resolved spectra of calixarene at 12 K are monitored. Spectral features, which demonstrate characteristic of energy transfer processes, are not observed. The depopulation of excited state density is mainly controlled by unimolecular decay process dominating other decay processes. The lifetime was found to be 2.6 $\pm$ 0.1 ns. For the case of calixarene mixed with naphthalene, the fluorescence spectrum shows that the band centered at 340 nm lies 2840 $cm^{-1}$ below the relatively broad 310 nm band found for calixarene crystals. The spectra also exhibit that the emission intensity increases with increasing calixarene concentration. The results are evident that the calixarene emission is quenched by the naphthalene. Phosphorescence of calixarene mixed with naphthalene crystals is observed to determine whether the emission is due to naphthalene. The phosphorescence peaks were compared with the ground-state vibrational frequencies of naphthalene and found to be in good agreement. The results indicate that inter-molecular energy transfer occurs between calixarene and naphthalene.

• 천문학회보
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• 제41권1호
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• pp.72.3-72.3
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• 2016

A massive envelope and a strong bipolar outflow are the two most distinct structures of youngest protostellar systems. We present observational results from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) toward the youngest (Class 0) protostellar system L1157. At an angular resolution of 5 arcseconds, we mapped its well-developed outflow in CO 2-1 over a span of approximately 5 arcminutes. Additionally, we imaged the central envelope with CO isotopes, CS, CN, and N2H+ with an angular resolution of about 2 arcseconds. We show that the bipolar outflow may be represented with a two jet model and constrain its physical properties such as precession/rotation directions, velocities, inclinations, and position angles via cube data fitting. In addition, we discuss the kinematic features of the envelope detected in CO isotopes and N2H+ and present the radius-dependent dust opacity spectral index.

• Structural Engineering and Mechanics
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• 제8권1호
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• pp.53-72
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• 1999

The most important features of linear soil-foundation-structure interaction are reviewed, using stochastic modeling and considering kinematic interaction, inertial interaction, and structural distortion as three separate stages of the dynamic response to the free-field motion. The way in which each of the three dynamic stages modifies the spectral density of the motion is studied, with the emphasis being on interpretation of these results, rather than on the development of new analysis techniques. Structural distortion and inertial interaction analysis are shown to be precisely modeled as linear filtering operations. Kinematic interaction, though, is more complicated, even though it has a filter-like effect on the frequency content of the motion.

• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.68-74
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• 2013

The surface enhanced Raman spectrum of juglone, a traditional natural dye, has been observed by a custom-built micro-Raman setup. The spectral features of juglone significantly differ from those of lawsone, a structural isomer of juglone; only small red shifts of the double bond stretching bands are observed, and strong SERS bands are observed in the lower frequency regions as well. The DFT computations reveal that juglone coordinated to an $Ag^+$ adatom with $H^+$ release best correlates with the observed vibrational characteristics in the SERS spectrum among the plausible configurations of juglone coordinated to an adatom on the Ag surface, in line with the previously studied lawsone case. The differences in the SERS spectra of juglone and lawsone are attributed to the different locations of the hydroxyl group in the two isomers.

• 천문학논총
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• 제11권1호
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• pp.49-55
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• 1996

In order to discover the candidates of emission-line galaxies towards Hydra Void, objective-prism observations using U.K. Schmidt Telescope were carried out. To search the emission feature of [0III]${\lambda}{\lambda}4959,5007$ for all objects on the plate, all observed prism plates were scanned with APM at the Royal Observatory and the copied direct R plates were scanned with PDS Microdensitometer operating in the Inter- University Center for National Science Research Facilities. By utilizing the "XIMTOOL" package, both spectral and direct images for the same field were displayed simultaneously on up and down windows separately. In case of distinct emission features for a certain object, corresponding direct object on the other window was examined through eyeballing to see whether this object is a galaxy. Through this procedure, we discovered in total 33 candidates of emission-line galaxies in a single field.

• 한국광학회지
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• 제8권3호
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• pp.175-182
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• 1997

가시광선 영역의 고분해능 3반사 망원경 광학계 설계를 위하여, 광학계의 기구적 제한사항을 만족함과 동시에 Flat Field Anastigmat 조건을 만족하는 해를 구하는 초기설계 기법이 제시되었으며, 이를 기초로 프로그램을 작성하여 F/14.5, 구경 600 mm, 시야 0.27.deg. * 1.3.deg.의 3반사 망원경광학계의 초기설계를 수행하였다. 초기 설계된 광학계의 최적화를 위하여 Code V를 사용하였으며, 그 결과로서 CCD의 모서리 부분 Field를 제외한 모든 Field에서 Nyquist Frequency에서의 MTF값이 0.5이상이었다.