• 천문학회보
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• 제45권1호
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• pp.35.3-36
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• 2020

The Time Domain Field is one of the future GTO program fields of JWST(JWST/GTO TDS), surveying about 14' diameter field at the North Eliptical Pole(NEP) with NIRCam/NIRISS. As a part of the multi-wavelength study of the field, we have obtained SCUBA-2 850㎛ mapping which reaches a depth of σrms = 0.9mJy/beam and detect 93 sources at S/N > 3.5 ― which are expected to be highly star-forming (SFR>400M◉/yr) galaxies at z ≳ 1.5-4 and pinpoint the location at <0. " 1 accuracy of 68 sub-mm sources by identifying VLA 3GHz radio counterparts. In this talk, we will introduce the SCUBA-2 JWST/GTO TDS project and the newly discovered sub-mm sources in this field.

• 한국자원식물학회지
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• 제25권6호
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• pp.670-681
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• 2012

Herb extracts commercially used in Korea were screened for PPAR-${\gamma}$ agonist test and ${\alpha}$-glucosidase inhibition assay. Total 16 herb plants had a PPAR-${\gamma}$ agonist activity. Specially, Alisma orientale Juz (108.41%), Ephedra sinica (98.22%), Sasa japonica Makino var. purpurascens Nakai (140.68%), Astragalus membranaceus Bunge (106.79%) and Cnidium officinale Makino (113.00%) showed high PPAR-${\gamma}$ agonist activity rate compared with rosiglitazone's (167.46%). And Cornus officinalis S. et Z. (90.3%), Cinnamomum cassia Blume (89.2%), Psoralea corylifolia L. (89.8%), Paeonia japonica (Makino) Miyabe (92.4%) and Paeonia suffruticosa Andr (93.2%), showed high ${\alpha}$-glucosidase inhibition rates. These results support previous reports of the efficacy of Oriental medicinal plants used for diabetes mellitus.

• 천문학논총
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• 제27권4호
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• pp.335-338
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• 2012

We present the $18{\mu}m$ luminosity function (LF) of galaxies at 0.006 < z < 0.8 (the average redshift is ~ 0.04) using the AKARI mid-infrared All-Sky Survey catalogue. We have selected 243 galaxies at $18{\mu}m$ from the Sloan Digital Sky Survey (SDSS) spectroscopic region. These galaxies then have been classified into five types; Seyfert 1 galaxies (Sy1, including quasars), Seyfert 2 galaxies (Sy2), low ionization narrow emission line galaxies (LINER), galaxies that are likely to contain both star formation and Active Galactic Nuclei (AGN) activities (composites), and star forming galaxies (SF) using optical emission lines such as the line width of $H{\alpha}$ or the emission line ratios of [OIII]/$H{\beta}$ and [NII]/$H{\alpha}$. As a result of constructing the LF of Sy1 and Sy2, we found the following results; (i) the number density ratio of Sy2 to Sy1 is $1.64{\pm}0.37$, larger than the results obtained from optical LF and (ii) the fraction of Sy2 in the entire AGN population may decrease with $18{\mu}m$ luminosity. These results suggest that most of the AGNs in the local universe are obscured by dust and the torus structure probably depends on the mid-infrared luminosity.

• Asian-Australasian Journal of Animal Sciences
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• 제14권7호
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• pp.941-946
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• 2001

The effects of various concentrations of saturated fatty acids (SFA; caprylic, capric and stearic acids) on the growth of the anaerobic fungus, Neocallimastix frontalis C5-1 isolated from the rumen of a Korean native goat were investigated. At higher concentrations of fatty acids (0.1%, w/v), the addition of SFA strongly decreased filter paper (FP) cellulose digestion and polysaccharide-degrading enzyme activity. The sensitivity of the rumen anaerobic fungus to the added fatty acids increased in the following order: caprylic ($C_{8:0}$)>capric($C_{10:0}$)>stearic($C_{18:0}$) acid, although stearic acid had no significant (p<0.05) inhibitory effects at any of the concentrations tested. However, the addition of SFA at lower concentrations (0.01 and 0.001% levels), did not inhibit FP cellulose degradation and enzyme activity. Furthermore, although these parameters were slightly stimulated by the addition of SFA, they were not statistically different from control values. This is the first report examining the effects of fatty acids on anaerobic gut fungi. We found that the lower levels of fatty acids used in this experiment were able to stimulate the growth and specific enzyme activities of rumen anaerobic fungi, whereas the higher levels of fatty acids were inhibitory with respect to fungal cellulolysis.

• The Korean Journal of Ecology
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• 제12권1호
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• pp.1-7
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• 1989

낙동강 하구 옥류등에 형성되어 있는 갈대, 천일사초 및 갯잔디 군락의 실소와 린의 동태를 조사하였다. 실소와 린의 흡수량 및 현존량은 식물군락의 물질생산과 단위 무게당 이들 무기영양소의 함량이 달랐다. 실소의 연 흡수량은 갈대, 천일사초, 갯잔디 군락에서 각각 224, 111 그리고 156 kg/ha이었고, 린의 연 흡수량은 각각 22, 29 그리고 21 kg/ha이었다. 염습지의 관속식물 군집은 다량의 질소와 인을 흡수하기 때문에 연안수의 당영양화를 일시적으로 경감시키는 역할을 할 수 있는 것으로 생각되었다.

• Weed & Turfgrass Science
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• 제6권2호
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• pp.136-150
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• 2017

잔디혹응애(Aceria zoysiae)는 잔디에 중요한 해충의 하나로 특히 한국잔디에 피해가 심하다. 본연구에서는 자생 채집 잔디 유전자원 보존원에서 잔디혹응애 저항성 잔디 개체의 선발을 위하여 잔디혹응애 피해를 조사하였다. 온실에서 295 계통의 자생지 채집 잔디를 대상으로 잔디혹응애 피해율을 조사한 결과, 잔디혹응애 피해는 잔디 종과 채집 계통별로 차이가 있었다. 잔디혹응애 피해가 가장 많은 잔디 초종은 들잔디와 중지였다. 들잔디가 97.6%의 개체들이 잔디혹응애 피해를 받았으며 중지와 갯잔디가 각각 87.7, 81.1%의 개체들이 잔디혹응애 피해를 받았다. 2개체의 왕잔디도 잔디혹응애 피해가 있었지만 일부 개체들은 온실과 야외에서 잔디혹응애 피해가 없었다. 야외에서 잔디혹응애 피해는 5월부터 발생하여 7월이후 급증하였다. 본 조사에서 잔디혹응애의 피해가 없는 잔디계통들은 향후 잔디혹응애 관리에 활용될 수 있을 것이다.

• Weed & Turfgrass Science
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• 제2권2호
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• pp.184-190
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• 2013

우리나라는 다양한 자생 중엽형 한국잔디 유전자원이 널리 분포하고 있으며, 유전자원 연구에 있어서 유전자원의 수집 및 확인이 중요하다. 본 연구는 해안 및 도서, 내륙지역에 자생하고 있는 중엽형 한국잔디를 지역별로 수집하여 형태적 특성 및 입지환경에 따른 변이를 알아보고자 수행되었다. 수집된 75개의 중엽형 한국잔디는 입지환경에 따라 다양한 형태적 변이가 존재하는 것을 확인하였고, 크게 해안(I군)과 내륙(II군)지역으로 두 개 그룹으로 나뉘었다. I군은 엽폭 3.7 mm, 소수당 종자수 29개, 종자길이 5.0 mm으로 갯잔디형 특성으로 나타났고, II군은 엽폭 4.4 mm, 소수당 종자수 42개, 종자길이 3.5 mm로 들잔디형으로 정확한 종간교잡의 정도를 파악하기 위해서는 추가적인 생육특성 및 분자생물학적 연구가 필요하다고 생각되었다. 상기 변이를 보이는 개체들은 앞으로 한국잔디의 변이를 확대하기 위한 귀중한 유전자원으로 보존가치가 높으며, 고품질 잔디육종을 위한 귀중한 자료로 활용가치가 높다고 판단된다.

• 천문학논총
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• 제32권1호
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• pp.225-230
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• 2017

The extragalactic background suggests half the energy generated by stars was reprocessed into the infrared (IR) by dust. At z~1.3, 90% of star formation is obscured by dust. To fully understand the cosmic star formation history, it is critical to investigate infrared emission. AKARI has made deep mid-IR observation using its continuous 9-band filters in the NEP field ($5.4deg^2$), using ~10% of the entire pointed observations available throughout its lifetime. However, there remain 11,000 AKARI infrared sources undetected with the previous CFHT/Megacam imaging (r ~25.9ABmag). Redshift and IR luminosity of these sources are unknown. These sources may contribute significantly to the cosmic star-formation rate density (CSFRD). For example, if they all lie at 1< z <2, the CSFRD will be twice as high at the epoch. We are carrying out deep imaging of the NEP field in 5 broad bands (g, r, i, z, and y) using Hyper Suprime-Camera (HSC), which has 1.5 deg field of view in diameter on Subaru 8m telescope. This will provide photometric redshift information, and thereby IR luminosity for the previously-undetected 11,000 faint AKARI IR sources. Combined with AKARI's mid-IR AGN/SF diagnosis, and accurate midIR luminosity measurement, this will allow a complete census of cosmic star-formation/AGN accretion history obscured by dust.

• 천문학논총
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• 제27권4호
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• pp.123-128
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• 2012

An overview of the North Ecliptic Pole (NEP) deep multi-wavelength survey covering from X-ray to radio wavelengths is presented. The main science objective of this multi-wavelength project is to unveil the star-formation and AGN activities obscured by dust in the violent epoch of the Universe (z=0.5-2), when the star formation and black-hole evolution activities were much stronger than the present. The NEP deep survey with AKARI/IRC consists of two survey projects: shallow wide (8.2 sq. deg, NEP-Wide) and the deep one (0.6 sq. deg, NEP-Deep). The NEP-Deep provides us with a $15{\mu}m$ or $18{\mu}m$ selected sample of several thousands of galaxies, the largest sample ever made at these wavelengths. A continuous filter coverage at mid-IR wavelengths (7, 9, 11, 15, 18, and $24{\mu}m$) is unique and vital to diagnose the contribution from starbursts and AGNs in the galaxies at the violent epoch. The recent updates of the ancillary data are also provided: optical/near-IR magnitudes (Subaru, CFHT), X-ray (Chandra), FUV/NUV (GALEX), radio (WSRT, GMRT), optical spectra (Keck/DEIMOS etc.), Subaru/FMOS, Herschel/SPIRE, and JCMT/SCUBA-2.

• 천문학논총
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• 제32권1호
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• pp.201-203
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• 2017

There exists strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. An important mechanism connecting AGN to their host galaxies is AGN feedback, potentially heating up or even expelling gas from galaxies. AGN feedback may hence be responsible for the eventual quenching of star formation and halting of galaxy growth. A rich multi-wavelength dataset ranging from the X-ray regime (Chandra), to far-IR (Herschel), and radio (WSRT) is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope, covering a total area on the sky of 5.4 sq. degrees. We investigate the star formation properties and possible signatures of radio feedback mechanisms in the host galaxies of 237 radio sources below redshift z = 2 and at a radio 1.4 GHz flux density limit of 0.1 mJy. Using broadband SED modelling, the nuclear and host galaxy components of these sources are studied simultaneously as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this field, while also offering evidence showcasing a link between AGN activity and host galaxy star formation. In particular, we show results supporting a maintenance type of feedback from powerful radio-jets.