충돌이온화평형 상태에서 [O I] λ6300과 Hα의 세기비

선광일,이대희 한국천문학회 2004 天文學論叢 Vol.19 No.1

In this paper, the intensity ratio of [O I] λ6300 and Hα lines, which plays an important role in the study of warm (or diffuse) ionized interstellar medium, is calculated assuming collisional ionization equilibrium (or coronal equilibrium). The calculated ratio is compared with the previous works, and with the observations, obtained by Reynolds (1989) and Reynolds et al. (1998) with the Wisconsin Ha Mapper facility, toward the directions that sample the faint interstellar emission-line background. The comparison confirms that most of the Ha originates from nearly fully ionized regions along the lines of sight rather than from partially ionized H I clouds or layers of H II on the surfaces of H I clouds.

OB형 별의 라이먼 연속 복사의 광도

선광일,Seon, Kwang-Il 한국천문학회 2007 天文學論叢 Vol.22 No.4

We are often faced with the task of having to estimate the hydrogen and helium ionizing luminosities of massive stars in the study of H II regions and the warm ionized medium (WIM). Using the results of the most complete compilation of stellar parameters (the effective temperature, stellar radius and surface gravity) and the latest Kurucz stellar atmosphere models, we calculate the ionizing photon luminosities in the $H^0\;and\;He^0$ continua from O3 to B5 stars. We compared the theoretical Lyman-continuum luminosity with the observationally inferred luminosity of the H II region around ${\alpha}$ Vir, and found that the theoretical value is higher than the observed value in contrast to the eariler result.

계장화 압입시험을 이용한 원전 배관 용접부의 파괴인성 평가

선광상(K. S. Seon),허용(Y. Huh),조성근(S.K. Cho),구재민(J.M. Koo),석창성(C.S. Seok) 한국정밀공학회 2007 한국정밀공학회 학술발표대회 논문집 Vol.2007 No.11월

성간먼지 산란 연구를 위한 효율적인 몬테카를로 알고리즘

선광일,Seon, Kwang-Il 한국천문학회 2010 天文學論叢 Vol.25 No.4

We developed an efficient Monte-Carlo algorithm to solve dust-scattering radiative transfer problems for continuum radiation. The method calculates the scattered intensities for various anisotropic factors ($g_i$) all at once, while actual photon packets are tracked following a scattering phase function given by a single anisotropic factor ($g_0$). The algorithm was tested by applying the method to a dust cloud embedding a star at the cloud center and found to provide accurate results within the statistical fluctuation that is intrinsic in Monte-Carlo simulations. It was found that adopting $g_0$ = 0.4 - 0.5 in the algorithm is most efficient. The method would be efficient in estimating the anisotropic factor of the interstellar dust by comparing the observed data with radiative transfer models.

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.

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.

서기 8-9세기 신라와 당과의 해상교통

선광기(Guangqi Sun),허일(Ihl Hugh) 한국항해항만학회 1996 한국항해항만학회 학술대회논문집 Vol.3 No.-

중국와 한반도와의 해상교통은 기나긴 역사의 물줄기로 흘러온다. 일찍이 서기 8-9세기 당과 신라간에 있었던 우호적인 린방항해는 역사상 전성기를 이루었다. 이 글은 중국, 한반도와 일본의 상관 고대문헌을 고찰한 기초상에서 청해진(오늘의 한국 완도) 장보고(Znang Bao-gao)대사를 대표로한 신라인들이 당나라에 대한 항해활동 및 그 활동이 남겨둔 역사의 자적을 연구함으로서 당시 당과 신라간의 주요한 해상교통선을 논증하였다. 본 연구는 아래와 같이 지적하고 있다. 1. 장보고는 서기 8-9세기 신라 항해역사상 아주 큰 영향력을 가진 대표인물로서 그는 이 시기 동북아시아 항해활동에 역사적 공헌하였다. 그가 오늘날 환국완도 및 중국 산동반도 등의 지역에 남긴 유적들은 중국과 한국 및 전체 한반도 교통연구에 고귀한 문화재로서 중시받을 가치를 지닌다. 2. 서기 8-9세기 신라와 당간 해상교통 노선은 쌍방 항해사들이 장기간의 왕래와 합작의 산물이며 이는 구체적으로 북항로. 중항로와 남항로등 세 갈래 주요 항로로 나누어진다. 그 가운데 : --- 중국 요령 연해로부터 신라에 도달하는 북항로는 역사가 영구한 전통성 항로인데 항해가 안전하지만 항로가 비교적 길다. --- 중국 산동반도로부터 신라에 이르는 중항로는 당시 쌍방 해상 왕래에 매우 중요한 항로로써 장보고 등 신라 항해사들이 중국과 왕래하던 주요항로이다. --- 중국 강소와 절강 연해로부터 신라에 이르는 남항로는 기본적으로 중항로가 남쪽으로서의 迎新 혹은 移動된 것으로서 그 왕래하던 시기는 당나라 이후 중국 송나라 시기인데 서기 10세기 이후이다. The marine communications between Korea Peninsula and China enjoyed such a long history that a relatively close marine relationship had been established early in the Qin&Han Dynasties which was around the Christian Era. During the 8th cent.A.D. and the 9th cent.A.D., the marine communications between Silla and Tang had flourished to such a great extent that an all-round setup of marine communications had been formed, namely, the simultaneous development of the North, the Middle and the South Routes with the Middle Route in the leading position. (see the Chart attached)

원자외선분광기 초기 On-orbit Calibration 결과

선광일,이대희,박장현,육인수,진호,남욱원,한원용,민경욱,유광선,이진근,신종호,오승한,Jerry Edelstein,Eric Korpela,Kaori Nishkida 한국우주과학회 2004 한국우주과학회보 Vol.13 No.1

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