• 천문학회보
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• 제42권1호
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• pp.42.3-42.3
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• 2017

We present the analysis of chemical abundances and kinematics for six hypervelocity star (HVS) candidates. These objects are G/K-type low-mass stars in the Galactic disk, while other HVSs previously found are B-type high-mass objects in the Galactic halo. The stellar orbits and kinematics of our HVS candidates suggest that they do not originate in the Galactic center or in an accretion event, indicative of yet-unknown mechanisms that produce kinematically-extreme disk stars. In order to study in detail their origin, we obtained medium-resolution (R~6000) spectra of these stars and derived abundances of several chemical elements (Mg, Ca, Si, Ti, Cr, Fe, and Ni). From the comparison of the chemical abundances with the Galactic stellar components (disk, bulge, halo, and dwarf galaxies) and the kinematic properties of our HVSs, we conclude that two of them are likely ejected from the Galactic disk, one originated from the Galactic center as for the young B-type HVSs, and the other one might be ejected from either the Galactic disk or other regions.

• 천문학논총
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• 제30권2호
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• pp.237-240
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• 2015

Classical novae (CNe) are interacting binary systems whose outbursts are powered by a thermonuclear runaway in accreted material onto the surface of a white dwarf (WD). The secondary star in such systems fills its Roche lobe and material is transferred onto the WD primary star via an accretion disk. Recurrent novae (RNe) show many similarities to CNe, but have had more than one recorded outburst. RNe play an important role as one of the suspected progenitor systems of Type Ia supernovae, which are used as primary distance indicators in cosmology. Thus, it is important to investigate the nature of their central binary systems to determine the relation between the parameters of the central system and the outburst type, and finally ascertain the population of novae that might be available to give rise to the progenitors of Type Ia SNe. A low outburst amplitude is adopted as a criterion that may help distinguish RNe from CNe and was therefore used to select targets for observations from ground-based observatories including the Liverpool Telescope and the Southern African Large Telescope as well as the full-sky space-based archive of the Solar Mass Ejection Imager (SMEI). We found that at least four objects currently classified as CNe are possibly RNe candidates based on their quiescent spectra. We also searched the SMEI archive for additional outbursts of bright CNe that might otherwise have been missed but did not find a conclusive example.

• 천문학회보
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• 제40권2호
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• pp.47.3-48
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• 2015

We present environmental effects on the galaxy evolution in the Virgo cluster focusing on intracluster medium - interstellar medium (ICM-ISM) interactions and gravitational interactions. We identify signatures of these environmental effects for 21 massive late-type galaxies based on the visual inspection of high resolution HI data from VLA Imaging of Virgo spirals in Atomic gas (VIVA) survey comparing with multi-wavelength data. We classify galaxies into three subgroups showing different environmental effects. First and second groups includes galaxies influenced by ongoing/active and past ram pressure stripping effect, respectively. Third group consists of galaxies undergoing gravitational interactions. Additionally, we define neighbor galaxies for each VIVA galaxies utilizing kinematic data from Extended Virgo Cluster Catalog. Assuming that neighbor galaxies share similar levels of environmental effects with host VIVA galaxies, we investigate environmental effects on galaxy properties in different subgroups using SDSS optical and GALEX ultraviolet photometric data. We find that dwarf neighbor galaxies in first and second groups show rapid quenching of their star formation (SF), while massive counterparts are still in SF activity. On the other hand, most third group galaxies show hints of SF activity regardless of their mass. We conclude that SF and evolution of galaxy in the cluster environment is closely linked to ICM-ISM interactions and dwarf galaxies seem to be more sensitive to this effect compared to massive counterparts.

• Journal of Astronomy and Space Sciences
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• 제21권4호
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• pp.383-390
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• 2004

2003년 9월에 발사되어 현재 임무수행중인 과학기술위성1호의 주탑재체 원자외선 분광기의 감도측정을 수행하였다. 이를 위하여 2003년 11월부터 2004년 5월의 기간동안 백색왜성 G191B2B와 O형 별인 Alpha-Cam, HD93521을 관측하였으며, 그 관측 데이터와 HUT(Hopkins Ultraviolet Telescope) 데이터를 비교하여 원자외선 분광기의 전 파장영역에 대한 유효면적을 계산하고, 그 결과를 비교 분석하였다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 추계학술대회
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• pp.100-100
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• 2018

Zoysia japonica Steud.(Zj) is a typical warm-season Korean lawn grass, which is used in many places such as river banks, roadside and soccer fields in Korea. Recently, it has also been used in school yards and the Saemangeum reclaimed land to reduce water pollution. Although the cultivated area of turfgrass is steadily increasing worldwide, it grows fast requiring frequent mowing and is difficult to grow in shady areas and the cold region. Therefore this study aims searching for useful gene(s) to develop abiotic stress tolerant and dwarf zoysiagrass. We isolated Ycf4 gene based on the sequence from Oryza sativa Japonica through RT-PCR and RACE PCR. Ultimately, open reading frame (ORF) of ZjYcf4 was 558bp long, encoding a protein of 186 amino acid residues. NCBI blast results showed that the ZjYcf4 protein is evolutionarily closely related to Ycf4 protein from Zoysia macrantha and Setaria italica (100% and 98%, respectively). To determine whether ZjYcf4 was involved in environmental stress in wild-type zoysiagrass, expression patterns of the gene were analyzed by real-time PCR under salt, cold and dark conditions. They were analyzed after each stress treatment for 3 hours. In salt and cold stresses, the expression was higher compared to control (3-fold and 1.5-fold, respectively), although there was a 1.6-fold decrease in expression under dark stress treatment. As reported previously, we suggest that ZjYcf4 gene affects abiotic stress such as salt, cold and dark.

• 천문학회보
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• 제37권1호
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• pp.36.2-36.2
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• 2012

The aim of this study was to explore the role of galaxy mergers on the formation and evolution of galaxies in galaxy clusters. For this purpose, u', g', r' deep optical imaging and multi-object spectroscopic observation were done for four rich Abell clusters at z ${\lesssim}$ 0.1 (A119, A2670, A3330, and A389) with a MOSAIC 2 CCD and Hydra spectrograph mounted on a Blanco 4-m telescope at CTIO. With the deep images, we found that about 25% of the bright red-sequence galaxies exhibited post-merger signatures in a cluster environment. This fraction was much higher than what was expected from the results of the field environment (-35%, van Dokkum 2005) and significantly low on-going merger fractions (about one-fifth of the field) appeared in the clusters currently. Taking advantage of the most up-to-date semi-analytic model, the results indicate that most of the post-merger galaxies may have carried over their merger features from their previous halo environment. All the brightest cluster galaxies in our cluster samples revealed faint structures in their halos as well as multiple nuclei in their centers seen in the deep optical images. We suggest that the mass of the BCGs increased mainly though major mergers at recent epochs based on their post-merger signatures and the large gaps in the total magnitudes between the BCGs and the second-rank BCGs. A UV bright tidal tail and tidal dwarf galaxy (TDG) candidates around the post-merger galaxy, NGC 4922, were discovered in the outskirts of the Coma cluster using the GALEX UV data. We did two-component stellar population modeling for the TDG candidates and the results indicate that they are an early form of dwarf galaxies frequently found around massive early-type galaxies in clusters. In conclusion, we suggest that the mergers of galaxies are an important driving force behind galaxy formation and evolution in cluster environments even until recent epochs.

• 한국작물학회지
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• 제42권2호
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• pp.160-165
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• 1997

팥 바이러스병에 대한 기초자료를 얻고자 병징의 유형과 생육 단계별 감량정도 및 수량에 미치는 영향을 조사하고 병징 유형별 바이러스를 분리 동정한 결과는 다음과 같다. 1. 팥에 발생되는 바이러스병의 병징은 크게 mosaic, yellow mosaic 및 severe mosaic의 3가지 군으로 분류되었으며 병징별 분포는 mosaic＞severe mosaic＞yellow mosaic 순이었다. 2. 성숙기까지 매개충 차단 재배시의 이병률은 1.5%(방임구 20.7%)로서 생육 후기에 감량될수록 이병률이 낮았으며 10a당 수량도 171kg으로서 방임구에 비하여 45% 증수되었다. 3. 지표식물 검정 결과 mosaic 유형은 CMV, yellow mosaic 유형은 AMV, severe mosaic 유형은 AzMV의 기주범위와 유사하였다. 4. 항혈청에 의한 각 병징별 반응결과 yellow mosaic 유형의 시요는 AMV 항 혈청과 mosaic 유형의 시요는 CMV의 항혈청과 침강선이 형성되어 각각 AMV 및 CMV의 한 계통으로 판정되었다. 5. 병징 유형별 전자현미경 관찰결과 yellow mosaic유형은 18~58$\times$18nm의 타원형 입자가 다수 관찰되었고 mosaic 증상의 시요에서는 직경 30nm의 구형 입자, severe mosaic병징의 시요에서는 730$\times$12nm의 사상형 입자와 봉입자가 관찰되었다.

• 한국동물학회지
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• 제37권1호
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• pp.49-57
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• 1994

In the course of an investigation on the morphological variation of Korean striped bittering, Acheilognathus vamatsutae Mori, two kinds of morrholoflical types were found. Some morphological characters were compared between them and multivariate analysis was conducted. Since the difference of the barbel length between them was very significant (p < 0.01,1-test), they should be designated as L-and 5-type Hshes: fishes with long barbels and those with should barbels, respectively. Lateral line scales, snout length and prepectoral length showed a tendency that the observation could be distinguished from each other (p < 0.05, Duncan's multiple range tests. There were no individuals over 70 mm BL in S-type and so S-type fishes were somewhat dwarf than L-type fishes. The two types were also clearly distinguished by multivariate analyses using cluster and discriminant analyses. According to the observation on the four populations of the Naktong River, the blue-green stripe on the body side and the white band on the margin of anal fin in males of S-type fishes were well developed through the year but those of males of L-type fishes completely disappeared or became slender during nonbreedins season as that of females. Of the seven localities surveved, there were no places that the two types cohabit. S-type fishes are limited only in the Kumho and Wichon River of the Naktong River system but L-type fishes are distributed more widely In the Hongchon, Mangvons, Somjin, Mirang and Panbyon River.

• 한국자원식물학회지
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• 제29권5호
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• pp.564-573
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• 2016

본 연구는 자생 끈끈이주걱(Drosera rotundifolia L.)의 원예적 활용도를 높이기 위하여 종자를 이용한 대량번식법 개발을 목적으로 수행되었다. 종자는 2011년 10월에 경기도 화성시 일대에서 채집되었으며, 건조상태(4 ± 1.0℃, 암조건)로 보관하면서 연구에 사용하였다. 종자의 장축과 단축의 길이는 각 1.58 ± 0.060, 0.21 ± 0.016 ㎜로 조사되어 ‘dwarf seeds’로 분류되었으며, 1,000립 중은 6.24 ± 0.172 ㎎로 측정되었다. 끈끈이주걱 종자는 12주의 저온습윤 처리 후 20~30℃, 명조건에서 휴면타파 및 발아가 진행되어 일정기간의 겨울온도가 요구되는 생리적(physiological) 휴면성이 확인되었다. 종자의 적정 발아조건은 20℃, 명조건(54.7%)으로 구명되었으며, 명조건 상의 비교적 고온인 25, 30℃에서는 온도가 높을수록 최종발아율이 감소하는 경향을 보였다. 적정 저온습윤 처리의 기간은 발아율과 발아세가 높고 평균발아일수 및 T₅₀의 단축이 가능한 14주로 판단되었다. 또한 GA₃ 200 ㎎/L + kinetin 20 ㎎/L 혼용처리는 발아율 향상뿐만 아니라 균일한 육묘를 위해서도 효과적인 화학적 발아촉진법으로 생각되었다.

• 한국농림기상학회지
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• 제9권1호
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• pp.55-60
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• 2007

무궁화 품종별 생장특성을 조사한 결과 수고는 불새 품종이 가장 높았고, 소양 품종이 가장 작은 값을 나타내었으며, 분지와 잎의 수는 백단심${\times}$경북1 품종이 가장 많았다. 무궁화 품종별 꽃 특성을 조사한 결과 선덕과 불새 품종의 화폭과 화고는 가장 높은 값을 보였으며, 소양 품종이 가장 작은 값을 나타내었다. 전반적으로 엽록소 함량(a, b, a+b)의 품종별 차이는 선덕과 불새 품종에서 가장 근소한 것으로 나타났다. 백단심${\times}$경북1과 소양 품종은 불새와 선덕 품종에 비하여 광보상점과 광포화점이 낮았으며, 암호흡 및 광합성능력 그리고 순량지수율도 모두 낮은 것으로 분석되었다. 이러한 결과로 비추어 볼 때, 무궁화 품종 백단심${\times}$경북1과 소양은 분화용으로서의 개발 가능성이 높은 것으로 평가된다.