• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.133-137
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• 2015

The Galactic center uniquely provides opportunities to resolve how star clusters form in neutral gas overdensities engulfed in a large-scale accretion flow. We have performed sensitive Green Bank 100m Telescope (GBT), Karl G. Jansky Very Large Array (JVLA), and Submillimeter Array (SMA) mapping observations of molecular gas and thermal dust emission surrounding the Galaxy's supermassive black hole (SMBH) Sgr $A^{\ast}$. We resolved several molecular gas streams orbiting the center on ${\gtrsim}10$ pc scales. Some of these gas streams appear connected to the well-known 2-4 pc scale molecular circumnuclear disk (CND). The CND may be the tidally trapped inner part of the large-scale accretion flow, which incorporates inflow via exterior gas filaments/arms, and ultimately feeds gas toward Sgr $A^{\ast}$. Our high resolution GBT+JVLA $NH_3$ images and SMA+JCMT 0.86 mm dust continuum image consistently reveal abundant dense molecular clumps in this region. These gas clumps are characterized by ${\gtrsim}100$ times higher virial masses than the derived molecular gas masses based on 0.86 mm dust continuum emission. In addition, Class I $CH_3OH$ masers and some $H_2O$ masers are observed to be well associated with the dense clumps. We propose that the resolved gas clumps may be pressurized gas reservoirs for feeding the formation of 1-10 solar-mass stars. These sources may be the most promising candidates for ALMA to probe the process of high-mass star-formation in the Galactic center.

• Journal of Korean Society of Rural Planning
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• v.23 no.3
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• pp.121-131
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• 2017

Although the educational facility are an important considerations on a social equity standpoint, educational environment in rural areas has been continuously deteriorated by numerous social problems such as decreasing birth rate and increasing of local school closing. The purpose of this study is to evaluate the accessibility of educational environment in rural areas on village level. First, we evaluate physical accessibility based on legally defined commuting distance. Second, the implication of village population of potential accessibility is analyzed. Lastly, the facility centrality index of each village is estimated for assessing the relations of educational accessibility. The main results of this study are as follows; (1) The accessibility of most villages in Pyeongchang-gun is vulnerable that 81.10% for elementary school, 73.17% for middle school, and 82.32% for high school, respectively; (2) The average commuting distance per student considering estimated number of students for each educational facilities indicated 2.75km for elementary school, 4.37km for middle school, and 5.79km for high school; (3) the facility centrality index is highly correlated to educational facilities but not to village population.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.577-586
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• 2018

In Korea, sustainability is mandatory in every field. University campuses are educational facilities that consume considerable amounts of energy. Therefore, many universities have tried to take advantage of the last opportunity to prepare students with sustainability and leadership. This study compared the green campus policy and evaluation criteria among Korea, US AASHE, UNEP, and ISCN-GULF to vitalize the green campus movement and suggest recent research data for the Korea green campus accreditation. The results are as follows: 1. new evaluation criteria need to be added to the certified green building total floor area ratio instead of adapting the G-SEED system in the Campus Resource & Environments category; 2. Korean Green Campus Evaluations need to be improved when expressing the campus individuality by choosing an increased number of credits and criteria; and 3. new evaluation criteria are required to secure the result, feedback, and products from curriculum updates in the Campus Education category.

• Journal of Conservation Science
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• v.36 no.5
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• pp.351-367
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• 2020

The pigments of three old and new celestial charts folding screens(『Celestial Chart(Folding Screen)』 and 『Old and New Celestial Charts, Eight-Panel Folding Screen』 of National Folk Museum of Korea and 『Koudou-Nanboku-Ryousouseizu』 of National Diet Library of Japan) were analyzed to estimate their dating. It was estimated that the 『Celestial Charts(Folding Screen)』 was painted using traditional pigments from the Joseon dynasty such as azurite, indigo lake, malachite, atacamite, vermilion, iron oxide, cochineal, gamboge, orpiment, lead white, talc and soot. The green and blue colors of the 『Old and New Celestial Charts, Eight-Panel Folding Screen』 and 『Koudou-Nanboku-Ryousouseizu』 were painted using artificial inorganic pigments such as emerald green and ultramarine blue. These pigments were imported from Europe post the mid-19th century. In the 『Old and New Celestial Chart, Eight-Panel Folding Screen』, only artificial inorganic pigments were used for green and blue colors. However in the 『Koudou-Nanboku-Ryousouseizu』, emerald green and atacamite in green color, and ultramarine blue and indigo lake in blue color were used together. Based on both the results of pigment analysis and the study of star charts and inscriptions, the 『Celestial Charts(Folding Screen)』 was painted post mid-18th century. The 『Koudou-Nanboku-Ryousouseizu』 and 『Old and New Celestial Charts, Eight-Panel Folding Screen』 were painted after green and blue artificial pigments were imported in the mid-19th century. The 『Koudou-Nanboku-Ryousouseizu』 in which both traditional and western artificial pigments were used, can be dated earlier than the 『Old and New Celestial Chart, Eight-Panel Folding Screen』.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.78.2-78.2
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• 2017

Post-starburst (E+A) galaxies are thought to be in the green valley transition phase between star-forming blue galaxies and quiescent red galaxies. They are identified by their unusual spectra characterized by strong Balmer absorption lines and weak emission lines, indicating a period of starburst followed by abrupt quenching. However, the underlying mechanism that drives the formation of E+A galaxies still remains contradictory or inconclusive. Thus, in order to differentiate between the different formation scenarios of E+A galaxies, we perform a statistical analysis of the environments of E+A galaxies. We spectroscopically identify a large sample of post-starburst galaxies from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) using a selection criteria based on $H{\delta}$ equivalent width. We report our findings and discuss their implications in the context of post-starburst galaxy formation.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.30.1-30.1
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• 2017

In the hope to detect low-surface brightness features (${\mu}_{r^{\prime}}{\sim}27\;mag\;arcsec^{-2}$), we carried out KASI-Yonsei Deep Imaging Survey for Clusters (KYDISC) targeting 14 local clusters at 0.016 < z < 0.145 using Magellan/IMACS telescope and CFHT/MegaCam. Out of 1450 cluster galaxies, 18% of galaxies show the signatures of galaxy mergers. We explore merger-driven changes from various point-of-view. We first examine color-magnitude relations, and find that galaxies related to recent mergers are populated more on blue color than their counterparts. Besides, we find the extremely low frequency of mergers on low-mass red-sequence galaxies, suggesting a migration of red galaxies into the green-valley region through merger-driven star-formation. We also study the mass-size relation of our sample, finding a larger galaxy size in galaxies related to recent mergers. Our results suggest that mergers can simultaneously change properties of galaxies, making outliers on galactic scaling relations.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.53-56
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• 2009

At room-temperature, a facile, seedless, and environmentally benign green route for the synthesis of star like PbS nanoclusters at 7 min in aqueous solution of 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM] [$EtSO_{4}$], room-temperature ionic liquid (RTIL), via ultrasonic irradiation is proposed. The X-ray diffraction studies display that the products are excellently crystallized in the form of cubic structure. An energy dispersive X-ray spectroscopy (EDX) investigation reveals the products are extremely pure. The absorption spectra of the product exhibit band gap energy of about 4.27 eV which shows an enormous blue shift of 3.86 eV that can be attributed to very small size of PbS nanoparticles produced and quantum confinement effect. A possible formation mechanism of the PbS nanoparticles using ultrasonic irradiation in aqueous solution of the RTIL is presented.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.39.2-39.2
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• 2019

Diffuse radio emissions at the outskirt of merging galaxy clusters called radio relics provide a unique channel to understand the merger history. We present a recent discovery of double radio relics in the cluster merger ZwCL1447+2619 from our recent Giant Metrewave Radio Telescope observations. Both Band 3 (300-500 MHz) and Band 4 (550-850 MHz) data reveal a large (~1Mpc) and thin (~40kpc) radio relic ~1Mpc from the cluster X-ray center and a small radio relic (~0.3 Mpc) on the opposite side. These remarkable radio data together with Subaru weak-lensing analysis and Chandra X-ray observations enable us to reconstruct the merger scenario. Our preliminary analysis suggests that the cluster ZwCL J1447+2619 is a post-merger near its returning phase. In addition, using Keck DEIMOS spectroscopy, we find many "green" and "blue" member galaxies are located between the radio relics, a possible indication of merger shock-driven star formation activities.

• ALGAE
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• v.33 no.1
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• pp.127-141
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• 2018

Low efficiency in microalgal biomass production was largely attributed to the low density of algal cell cultures. Though mutations that reduced the level of chlorophyll or pigment content increased efficiency of photon usage and thus the cell-culture density under high-illumination growth conditions (e.g., >$500{\mu}mol\;photon\;m^{-2}\;s^{-1}$), it was unclear whether algae could increase cell-culture density under low-illumination conditions (e.g., ${\sim}50{\mu}mol\;photon\;m^{-2}\;s^{-1}$). To address this question, we performed forward genetic screening in Chlamydomonas reinhardtii. A pool of >1,000 insertional mutants was constructed and subjected to continuous subcultures in shaking flasks under low-illumination conditions. Complexity of restriction fragment length polymorphism (RFLP) pattern in cultures indicated the degree of heterogeneity of mutant populations. We showed that the levels of RFLP complexity decreased when cycles of subculture increased, suggesting that cultures were gradually populated by high cell-culture density (HCD) strains. Analysis of the 3 isolated HCD mutants after 30 cycles of subcultures confirmed that their maximal biomass production was 50-100% higher than that of wild type under low-illumination. Furthermore, levels of chlorophyll content in HCD mutant strains were similar to that of wild type. Inverse polymerase chain reaction analysis identified the locus of insertion in two of three HCD strains. Molecular and transcriptomic analyses suggested that two HCD mutants were a result of the gain-of-function phenotype, both linking to the abnormality of mitochondrial functions. Taken together, our results demonstrate that HCD strains can be obtained through continuous subcultures under low illumination conditions.

• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.125-130
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• 2010

Dollar spot and brown patch disease are the most economically important disease for highly maintained turfgrass area such as golf courses. Previous researches indicated that various natural fertilizers are good nitrogen (N) sources and they may lead to turf disease suppression because disease suppression by natural N sources may be due to microbial activity increased. Increased microbial activities in soil reduce the activity of plant pathogen. The objective of this study was to evaluate efficacy of various N sources to suppress dollar spot and brown patch on creeping bentgrass. The seven N sources and fungicide combinations were investigated for turf disease suppression. $Emerald^{TM}$ and $ProStar^{TM}$ were applied for the applications of fungicide combination. No differences were found on turf quality among N source treatments. However, there was significant difference on turf quality between fungicide combination and fungicide combination plus urea. Overall, N source had no significant effects on suppression of dollar spot and brown patch. Although there were a few differences among N source treatments, fungicide treatments were needed for turf disease suppression for highly maintained turfgrass area such as golf courses.