• The Bulletin of The Korean Astronomical Society
• /
• v.45 no.1
• /
• pp.35.3-36
• /
• 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.

• Korean Journal of Plant Resources
• /
• v.25 no.6
• /
• pp.670-681
• /
• 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.

• Publications of The Korean Astronomical Society
• /
• v.27 no.4
• /
• pp.335-338
• /
• 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
• /
• v.14 no.7
• /
• pp.941-946
• /
• 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
• /
• v.12 no.1
• /
• pp.1-7
• /
• 1989

We studied primary production, nitrogen and phosphorus dynamics in a salt marsh of Okryutung at Nakdong River estuary. The standing biomass in Phragmites longivalvis, Carex scabrifolia and Zoysia sinica stand was $5.48kg/\textrm{m}^2,{\;}1.94kg/\textrm{m}^2{\;}and{\;}1.95kg/\textrm{m}^2$, respectively. The peak above-ground biomass in each stand was $1.99kg/\textrm{m}^2,{\;}0.74kg/\textrm{m}^2{\;}and{\;}1.03kg/\textrm{m}^2$, respectively. Soil nitrogen decreased from the onset of growing seson till July, and then increased. Seasonal patterns of soil phosphorus were different from stand to stand. Nitrogen concentrations of above-ground plant tissus were quite different among the plant species at the very beginning of the growing season, however, they became similar as the plants grow. Seasonal pattern of phosphrous in C. scabrifolia roots was quite different from those other two species. Nitrogen absorbed by plants during season in P. longivalvis, C. scabrifolia and Z. sinicia stand was 224kg/ha, 111kg/ha, 156kg/ha, respectively. Phosphorus taken up by plants was 22kg/ha, 29kg/ha and 21kg/ha, respectively. Because the vascular plants growing at salt marshes can immobilize large quantities of nitrogen and phosphorus, salt marsh vegetation can be sued for preventing the pollution of coastal sea water.

• Weed & Turfgrass Science
• /
• v.6 no.2
• /
• pp.136-150
• /
• 2017

Zoysiagrass mite, Aceria zoysiae is one of the main turfgrass pests causing significant damage on zoysiagrass. In this study we investigated damage by zoysiagrass mite for the selection of zoysiagrass mite-resistance turfgrass individual in natural collected turfgrass isolates transplanted in genetic resources conservation area. In the results of investigation of 295 turfgrass isolates collected from Korea, damage level was different depending on turfgrass species and individuals. Zoysia japonica was highly damaged representing 97.6%, followed by hybrid zoysia and Z. sinica with damage percentages of 87.7% and 81.1% respectively. Additionally, 2 individuals of Z. macrostachya were also damaged by zoysiagrass mite. However several individuals were not damaged by zoysiagrass mite in green house and field. Damage by zoysiagrass mite was occurred from May and peak at after July in field. The study highlighted some important resistant turfgrass individuals which can be used in the management of zoysiagrass mite.

• Weed & Turfgrass Science
• /
• v.2 no.2
• /
• pp.184-190
• /
• 2013

It is important for genetic resources to collect and identify in native medium-leaf type zoysiagrasses species distributed in Korea. This study was conducted to investigate morphological variation and characteristics of native medium-leaf type zoysiagrasses from coastal, island and inland regions in Korea. Among them, 75 collected lines was confirmed to have various morphological variations, accessions were classified into 2 main based group coastal and inland regions by morphological characteristics and site environment. Group I included Z. sinica type, this group showed 3.7 mm in leaf width, 29 in number of seed per spikelet and 5.0 mm in seed length. Group II included Z. japonica type, this group showed 4.4 mm in leaf width, 42 in number of seed per spikelet and 3.5 mm in seed length. There is a need for additional research on growth characteristics and the molecular level for the introgressive hybridization between species which confirmed that cross-pollination is possible due to protogyny. The individuals showing variations should be preserved as valuable genetic resources for the expansion of variations in zoysiagrasses, and the results of this investigation on the genetic resources collected will be highly valuable in breeding high quality turfgrass.

• Publications of The Korean Astronomical Society
• /
• v.32 no.1
• /
• pp.225-230
• /
• 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.

• Publications of The Korean Astronomical Society
• /
• v.27 no.4
• /
• pp.123-128
• /
• 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.

• Publications of The Korean Astronomical Society
• /
• v.32 no.1
• /
• pp.201-203
• /
• 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.