최소자승법을 이용한 다수 베타 방출 핵종 혼합물의 방사능 분석

선광일,남욱원,공경남,김창규,이동명,이상국 대한방사선 방어학회 2001 방사선방어학회지 Vol.26 No.4

베타선 스펙트럼의 최대 에너지가 확실하게 구별되는 2개의 핵종만을 포함하는 혼합시료의 경우에는 최대 에너지가 다르다는 점을 이용하여 손쉽게 각 핵종의 방사능값을 측정할 수 있다. 그러나 3개 이상의 베타 방출 핵종이 포함된 혼합물에 대해서는 각 핵종의 스펙트럼이 서로 겹치기 때문에 이러한 방법으로 구해진 방사능값은 신뢰도가 떨어지게 된다. 따라서, 본 연구에서는 최소자승법을 이용하여 혼합물의 중첩된 베타선 스펙트럼을 각각 분리 정량분석할 수 있는 밥법을 제시하였다. 또한, 실제로 4개의 베타 방출 핵종 ^3H, ^14C, ^16Cl, 90Sr)이 혼합된 사료를 조제하여 본 분석법을 검증한 결과 최고치 Reference value)와 분석치가 7% 이내에서 잘 일치함을 보였다. It is possible to count and perform quench correction on two β-label samples so long as the maximum β-energies are sufficiently different. However, when the coventional technique is applied to the radioassay of a mixture of more than three nuclides, the reliability of the activiteis determined is considerably reduced, resulting from the large overlapping of liquid scintillation pulse height distributions of ezch nuclide. A technique that allows the activities of multiple β-labeled samples to be radioassayed was proposed by using the least square method. The technique was applied to mixture samples of ^3H, ^14C, ^16Cl, and ^90Sr. The analytical values were in good agreement with the reference values within 7% relstive error.

천문관측용 우주광학계

선광일,한원용 한국광학회 2002 광학과 기술 Vol.6 No.4

Ionization balance for Ni ions under coronal equilibrium

선광일,박일흥,천병구,남육원,한원용 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.I

The available electron-impact ionization cross-sections and recombination rate coefficients for Ni ions are reviewed, and the fit parameters to Younger's empirical formula for the ionization crosssections of Ni1+, Ni3+, and Ni5+ through Ni8+ are updated. Also presented are the calculations of the ionization balance for the ions under coronal equilibrium. The calculated ionic abundance fractions are compared with those of previous work. A possible implication of the long-standing problem of Nickel overabundances in several classes of astronomical objects is also discussed.

FIMS 타입의 우주관측용 원자외선분광기 광학설계

선광일,육인수,유광선,이대희,SEON KWANG-IL,YUK IN-SOO,RYU KWANG-SUN,LEE DAE-HEE 한국천문학회 2004 天文學論叢 Vol.19 No.1

An imaging spectrograph concept optimized for extended far-ultraviolet emission sources is presented. Although the design was originally developed for FIMS aboard the first Korean science satellite STSAT-l launched on September 27, 2003, no rigorous theoretical background of the spectrograph design has been published. The spectrograph design employs an off-axis parabolic cylinder mirror in front of a slit that guides lights to a diffraction grating. The concave grating provides moderate spatial resolution over a large field of view. This mapping capability is absent in most astronomical instruments but is crucial to the understanding of the nature of a variety of astrophysical phenomena. The aberration theory presented in this paper can be extended to holographic gratings in order to improve the spatial as well as the spectral resolutions.

원자외선분광기 LVPS 및 TDC의 열해석

선광일,이진근,육인수,유광선,박장현,진호,남욱원,민경욱,한원용,Jerry Edelstein,Eric Kopela 한국우주과학회 2001 한국우주과학회보 Vol.10 No.2

MONTE-CARLO RADIATIVE TRANSFER MODEL OF THE DIFFUSE GALACTIC LIGHT

선광일 한국천문학회 2015 Journal of The Korean Astronomical Society Vol.48 No.1

Monte-Carlo radiative models of the diffuse Galactic light (DGL) in our Galaxy are calcu-lated using the dust radiative transfer code MoCafe, which is three-dimensional and takes full accountof multiple scattering. The code is recently updated to use a fast voxel traversal algorithm, which hasdramatically increased the computing speed. The radiative transfer models are calculated with the gen-erally accepted dust scale-height of 0.1 kpc. The stellar scale-heights are assumed to be 0.1 or 0.35 kpc,appropriate for far-ultraviolet (FUV) and optical wavelengths, respectively. The face-on optical depth,measured perpendicular to the Galactic plane, is also varied from 0.2 to 0.6, suitable to the optical to FUVwavelengths, respectively. We find that the DGL at high Galactic latitudes is mostly due to backwardor large-angle scattering of starlight originating from the local stars within a radial distance of r < 0.5kpc from the Earth. On the other hand, the DGL measured in the Galactic plane is mostly due to starsat a distance range that corresponds to an optical depth of ≈ 1 measured from the Earth. Therefore,the low-latitude DGL at the FUV wavelength band would be mostly caused by the stars located at adistance of r . 0.5 kpc and the optical DGL near the Galactic plane mainly originates from stars withina distance range of 1 . r . 2 kpc. We also calculate the radiative transfer models in a clumpy two-phasemedium. The clumpy two-phase models provide lower intensities at high Galactic latitudes compared tothe uniform density models, because of the lower effective optical depth in clumpy media. However, nosignificant difference in the intensity at the Galactic plane is found.

과학위성 1호 원자외선 분광기의 회절격자 열해석

선광일,육인수,유광선,박장현,남욱원,강경인,선종호,한원용,민경욱,Jerry Edelstein,Ray Chung 한국우주과학회 2001 한국우주과학회보 Vol.10 No.1

Adaptive Smoothing of Photon-Counting Images

선광일,육인수,남욱원,박장현,이대희,문홍규,진호,한원용,신종호,김일중,유광선,민경욱,Jerry Edelstein,Eric Korpela,Kaori Nishikida 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1

We present a method for adaptively smoothing an astronomical image. The method surpasses the previous algorithms in that the present method takes the spatial variations in the exposure into account. The method adjusts the smoothing scale such that, at every position in the image, theresulting smoothed image has a signal-to-noise ratio above a prescribed critical value. We applied our new method to data from FIMS (Far-ultraviolet IMaging Spectrograph; also known as SPEAR), the main payload of the ¯rst Korean scienti¯c satellite \STSAT-1." The negative signal problem often encountered in photon-counting experiments after subtracting the background rate from an estimate of the signal plus background rate, which is also commonly found in FIMS data, is avoided by adopting the correct estimate of the source signal rate based on Bayesian probability theory We present a method for adaptively smoothing an astronomical image. The method surpasses the previous algorithms in that the present method takes the spatial variations in the exposure intoaccount. The method adjusts the smoothing scale such that, at every position in the image, theresulting smoothed image has a signal-to-noise ratio above a prescribed critical value. We applied our new method to data from FIMS (Far-ultraviolet IMaging Spectrograph; also known as SPEAR),the main payload of the ¯rst Korean scienti¯c satellite \STSAT-1." The negative signal problem often encountered in photon-counting experiments after subtracting the background rate from an estimate of the signal plus background rate, which is also commonly found in FIMS data, is avoidedby adopting the correct estimate of the source signal rate based on Bayesian probability theory.

평행평면의 성간먼지층에 의한 복사광의 산란

선광일,Seon, Kwang-Il 한국천문학회 2008 天文學論叢 Vol.23 No.2

We present analytical approximations for calculating the scattering and escape of non-ionizing photons from a plane-parallel medium with uniformly illuminated by external sources. We compare the results with the case of a spherical dust cloud. It is found that more scattering and absorption occur in the plane-parallel geometry than in the spherical geometry when the optical depth perpendicular to the plane and the radial optical depth of the sphere are the same. The results can provide an approximate way to estimate radiative transfer in a variety interstellar conditions and can be applied to the dust-scattered diffuse Galactic light.

확산 은하 복사광에 대한 평면 평행 모델

선광일,Seon, Kwang-Il 한국천문학회 2009 天文學論叢 Vol.24 No.1

A plane-parallel model of the diffuse Galactic light (DGL) is calculated assuming exponential disks of interstellar dust and OB stars, by solving exactly the radiative transfer equation using an iterative method. We perform a radiative transfer calculation for a model with generally accepted scale heights of stellar and dust distribution and compare the results with those of van de Hulst & de Jong for a constant slab model. We also find that the intensity extrapolated to zero dust optical depth has a negative value, against to the usual expectation.