• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.773-782
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• 2016

The performance of the CT-TDLAS (computed tomography-tunable diode laser absorption spectroscopy) is strongly dependent upon the line broadening functions. The line of the laser beam used in the TDLAS is scattered by the natural broadening, the collisional broadening and the doppler broadening. The influence of the natural broadening to the experimental spectra obtained in the TDLAS is negligible. The influences of the collisional broadening and the doppler broadening to the experimental spectra are relatively large, in high pressure gas flows and in high temperature low pressure gas flows, respectively. In this study, optimal coefficients are proposed for the doppler broadening function by using the experimental data obtained in a flat burner test. The optimal coefficients were ${\gamma}_j=0.16$ and n=0.37. Using these coefficients, the temperature and concentration distributions at the engine exhaust gas pipe have been calculated showing their validities.

• 한국분말재료학회지
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• 제10권5호
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• pp.318-324
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• 2003

The nano-scale crystallite sizes of uranium oxide powders in simulated spent fuel were measured by the neutron diffraction line broadening method in order to analyze the sintering behavior of the dry process fuel. The mixed $UO_2$ and fission product powders were dry-milled in an attritor for 30, 60, and 120 min. The diffraction patterns of the powders were obtained by using the high resolution powder diffractometer in the HANARO research reactor. Diffraction line broadening due to crystallite size was measured using various techniques such as the Stokes' deconvolution, profile fitting methods using Cauchy function, Gaussian function, and Voigt function, and the Warren-Averbach method. The non-uniform strain, stacking fault and twin probability were measured using the information from the diffraction pattern. The realistic crystallite size could be obtained after separation of the contribution from the non-uniform strain, stacking fault and twin.

• 한국광학회지
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• 제14권3호
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• pp.279-285
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• 2003

InGaAsP/InP 비대치 다중 양자우물 구조에서 모드 이득의 이론 및 실험적 해석을 통해 광대역 이득특성을 확인하였고, 여러가지 선폭증가 함수를 적용하여 비대칭 선폭증가 함수가 가장 실험치에 근접한 모델임을 확인하였다. 광대역 이득 대역폭을 얻기 위한 활성층 구조를 설계하여 RWG형 FP-LD를 제작하였고, 공진기 길이가 400 $\mu\textrm{m}$에서 발진개시 전류는 36 ㎃, 주입전류가 33 ㎃에서 -1 ㏈ 이득폭은 45 nm, -3 ㏈ 폭은 80 nm을 얻을 수 있었다.

• 천문학회지
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• 제33권1호
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• pp.57-73
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• 2000

We have done a spectroscopic study of the solar transition region using high resolution UV & EUV data obtained by SUMER(Solar Ultraviolet Measurements of Emitted Radiation) on board SOHO(Solar and Heliospheric Observatory). Optically thin and conspicuous emission lines observed at the solar limb are carefully selected to acquire average values of physical parameters for the quiet region as a function of radial distance. Our main results found from the present study can be summarized as follows. 1) Nonthermal velocities estimated from various UV lines do not decrease with height at least within one total line intensity scale height above the limb. 2) Nonthermal velocity distribution with temperature is very similar to that of the disk center, in the sense that its peak is located around $2{\times}10^5 K$, but the value is systematically larger than that of the disk. 3) It is found that nonthermal velocity is inversely proportional. to quadratic root of electron density up to about 10 arc seconds above the limb, i.e. ${\xi}\~N_e^{-1/4}$, implying that the observed nonthermal broadening can be attributed to Alfven waves passing through the medium. 41 Electron density estimated from the O V 629/760 line ratio is found to range from about $1{\times}10^{10}cm^{-3}$ to $2{\times} 10^{12}cm^{-3}$ in the transition region.

• 천문학논총
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• 제22권2호
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• pp.35-41
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• 2007

We present the result of radial velocity observation of a W UMa type binary star EX Leo. We observed the star on February 16, 2003, using Long-Slit spectrograph of BOAO(Bohyunsan Optical Astronomical Observatory). Since the spectral lines are broad due to its fast rotation, it is difficult to distinguish two radial velocities from cross correlation function. Instead of cross correlation function, we used broadening function to develop our own code which estimate the radial velocity of the broadened line spectra. With our own code, radial velocities of primary and secondary stars are derived simultaneously. From the radial velocity curve fit, we obtained $K_1=50.24{\pm}8.29km/s$ and $K_2=254.05{\pm}20.984km/s$ respectively.

• Journal of Astronomy and Space Sciences
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• 제21권4호
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• pp.263-274
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• 2004

한국천문연구원 보현산 천문대(Bohyunsan Optical Astronomical Observatory, BOAO)의 BOES(Bohyunsan Optical Echelle Spectrograph)를 이용하여 2003년 2월 26-27일 이틀간에 걸쳐 BX And의 고분산 관측을 수행하였다. 이 관측을 통하여 얻은 스펙트럼은 총 38개로 위상 $0.1{\sim}0.3$에 이르는 구간을 제외하고는 전위상에 걸쳐 골고루 관측이 이루어졌다. 시선속도를 구하기 위하여 BF(Broadening Function)와 CCF(Cross-Correlation Function)를 이용한 방법 이 모두 사용되었다. CCF를 이용하였을 때는 주성의 시선속도만을 얻은 반면, BF인 경우, 주성과 반성의 시선속도 모두를 잘 결정할 수 있었다. 새로운 시선속도곡선으로부터 주성과 반성의 최대 시선속도를 각각 $K_1=96.1km/s$와 $K_2=196.6km/s$으로 얻었으며, 이를 Bell et al.(1990)의 측광해와 결합하여 BX And의 절대 물리량을 새롭게 결정하였다.

• 한국전기전자재료학회논문지
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• 제31권7호
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• pp.443-449
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• 2018

We investigated the temperature-dependent photoluminescence spectroscopy of colloidal InZnP/ZnSe/ZnS (core/shell/shell) quantum dots with varying ZnSe and ZnS shell thickness in the 278~363 K temperature range. Temperature-dependent photoluminescence of the InZnP-based quantum dot samples reveal red-shifting of the photoluminescence peaks, thermal quenching of photoluminescence, and broadening of bandwidth with increasing temperature. The degree of band-gap shifting and line broadening as a function of temperature is affected little by shell composition and thickness. However, the thermal quenching of the photoluminescence is strongly dependent on the shell components. The irreversible photoluminescence quenching behavior is dominant for thin-shell-deposited InZnP quantum dots, whereas thick-shelled InZnP quantum dots exhibit superior thermal stability of the photoluminescence intensity.

• Journal of Astronomy and Space Sciences
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• 제36권3호
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• pp.115-119
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• 2019

This paper is a part of the series on positron annihilation spectroscopy of two-phase diffuse gas-and-dust aggregates, such as interstellar medium and the young remnants of type II supernovae. The results obtained from prior studies were applied here to detect the relationship between the processes of the annihilation of the K-shell electrons and incident positrons, and the effects of these processes on the optical spectra of their respective atoms. Particular attention was paid to the Doppler broadening of their optical lines. The relationship between the atomic mass of the elements and the Doppler broadening, ${\Delta}{\lambda}_D$ (${\AA}$), of their emission lines as produced in these processes was established. This relationship is also illustrated for isotope sets of light elements, namely $^3_2He$, $^6_3Li$, $^7_3Be$, $^{10}_5B$ and $^{11}_5B$. A direct correlation between the ${\gamma}-line$ luminosity ( $E_{\gamma}=1.022MeV$) and ${\Delta}{\lambda}_D$ (${\AA}$) was proved virtually. Qualitative estimates of the structure of such lines depending on the positron velocity distribution function, f(E), were made. The results are presented in tabular form and can be used to set up the objectives of further studies on active galactic nuclei and young remnants of type II supernovae.

• Journal of Astronomy and Space Sciences
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• 제4권1호
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• pp.35-45
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• 1987

The peculiar elliptical (EOp) galaxy NGC 4486 and two KOII comparison stars HR5450, HR6935 were observed spectroscopically using the 74-inch telescope and Image Tube at Mt. Stomlo Observatory. From the Gaussian Broadening Function, broadened spectrum of two comparison stars were computed for the range between wavelength 4800$\AA$ and 5400$\AA$. Velocity dispersions in the line of sight of M87 were obtained by visual fitting. The fitted velocity dispersion is 450 km/sec at the nucleus, 350km/sec at r=12", and 300km/sec at r=24". Using the photometric data and the central value of velocity dispersion, we determined the mass of M87. From <$r^{2/4}$ law and the Virial theorem the calculated total mass in $2.1\times10^{12}M_\odot$ and from the King Model $M=1.2\times10^{12}M_\odot$. And M/L ratio of M87 is about 30.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.2981-2984
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• 2012

Active site mapping has been done for ${\Delta}^5$-3-ketosteroid isomerase (KSI) by analyses of paramagnetic effect on $^1H-^{15}N$ HSQC spectra using 4-hydroxyl-2,2,6,6-tetramethylpiperidinyl-1-oxy (HyTEMPO) and an intermediate analog (equilenin). Our result revealed that residues in hydrophobic cavity of KSI, particularly active site region, mainly experienced a high line-broadening effect of NMR signal with HyTEMPO, while they experienced full recovery of a lineshape upon the addition of equilenin. The mapped region was very similar to the active site of KSI as described by the crystal structure. These observations indicate that a combined use of paramagnetic reagent and substrate (or analog) could rapidly identify the residues in potential active site of KSI, and can be applied to the analysis of both active site and function in unknown protein.