• 천문학회보
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• 제39권2호
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• pp.69.2-69.2
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• 2014

We present space-based near-IR (NIR) and optical photometry of globular clusters (GCs) of 16 early-type galaxies in the Fornax and Virgo Clusters. The NIR imaging data for the nearby galaxies was acquired with the IR Channel of the Wide Field Camera 3 (WFC3/IR) in the F110W ($J_{110}$) and F160W ($H_{160}$) bandpasses. We introduce the full sample of our WFC3/IR program, describe data reductions and photometric measurements including GC candidate selection criteria, and then show selected GCs' color-magnitude diagrams. The tilted features in the diagrams related to the morphological types of host galaxies are discussed in the context of galaxy formation and evolution histories. Combining F475W ($g_{475}$) and F850LP ($z_{850}$) data taken from the Advanced Camera for Surveys Virgo and Fornax Cluster Surveys with our NIR data, we investigate the bimodality in optical-NIR color distribution and the nonlinear feature of the optical-NIR color relation as a function of optical color for these extragalactic GC systems.

• 천문학회지
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• 제48권4호
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• pp.213-228
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• 2015

The Horizon Run 4 is a cosmological N-body simulation designed for the study of coupled evolution between galaxies and large-scale structures of the Universe, and for the test of galaxy formation models. Using 6300³ gravitating particles in a cubic box of L_box = 3150 h⁻¹Mpc, we build a dense forest of halo merger trees to trace the halo merger history with a halo mass resolution scale down to M_s = 2.7 × 10¹¹h⁻¹M_⊙. We build a set of particle and halo data, which can serve as testbeds for comparison of cosmological models and gravitational theories with observations. We find that the FoF halo mass function shows a substantial deviation from the universal form with tangible redshift evolution of amplitude and shape. At higher redshifts, the amplitude of the mass function is lower, and the functional form is shifted toward larger values of ln(1/σ). We also find that the baryonic acoustic oscillation feature in the two-point correlation function of mock galaxies becomes broader with a peak position moving to smaller scales and the peak amplitude decreasing for increasing directional cosine μ compared to the linear predictions. From the halo merger trees built from halo data at 75 redshifts, we measure the half-mass epoch of halos and find that less massive halos tend to reach half of their current mass at higher redshifts. Simulation outputs including snapshot data, past lightcone space data, and halo merger data are available at http://sdss.kias.re.kr/astro/Horizon-Run4.

• Environmental Engineering Research
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• 제17권2호
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• pp.69-75
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• 2012

Composting of water hyacinth, mixed with cattle manure, rice husk and sawdust in four different proportions, was performed in a pilot scale rotary drum composter. The physico-chemical characteristics, i.e., temperature, moisture content, pH, electrical conductivity, total organic matter (OM), nitrogen dynamics and nutrients were evaluated during the 20 days composting process. The stabilities of the composts were also investigated with respirometric analysis, i.e., $CO_2$ evolution rates and oxygen uptake rate (OUR). Among all trials, trial 1 (6 water hyacinth, 3 cattle manure, 1 rice husk) indicated the best composting mix, as shown by the highest temperature profile and OM loss, and lowest $CO_2$ evolution rate and OUR.

• Animal Systematics, Evolution and Diversity
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• 제24권2호
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• pp.205-208
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• 2008

Two new marine sponges in family Halichondriidae, Halichondria ulleungensis n. sp. and H. hongdoenesis n. sp. are collected from Ulleungdo Island and Hongdo Island, Korea by SCUBA diving during 2003-2004. H. ulleungensis n. sp. is similar to H. corrugata Diaz, Pomponi and van Soest, 1993 in the type of spicule, but it is different in growth form and choanosomal skeleton. The growth form is encrusting, with numerous erected cylindrical tube, comparing with massive-lobate of H. corrugata. The choanosomal skeleton is confused with loosely arranged oxea tract, comparing with densely tracts with many spicules of H. corrugata. H. hongdoenesis n. sp. is similar to H. surrubicunda Hoshino, 1981 in type of spicule and growth form, but this species has two kinds (thick and thin) of oxea.

• 천문학회보
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• 제39권1호
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• pp.44.2-44.2
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• 2014

We investigate the influence of neighboring galaxies as a component of the local environment. Based on the SDSS data release 7 and the KIAS value-added galaxy catalog, we have constructed a galaxy pair catalog by matching each galaxy with its nearest and its most tidally-influential neighbor. In particular, we examine the star formation rate (SFR) derived from their optical u-r color and $H{\alpha}$ emission as functions of neighbor's distance, tidal force, and morphological type. The results are as follows. (1) The $H{\alpha}$-based SFR of galaxies with close companions is enhanced by up to a factor of three regardless of neighbor's morphology, when compared to isolated counterparts. (2) The mean u-r color of galaxies along with early-type galaxies is redder than that of isolated ones, yet bluer with late-types. (3) The galaxies with late-type companions mostly show higher SFR than those with early-types. The results suggest that the role played by neighboring galaxies are two-fold; (a) the tidal effect on the shorter scale of time and of distance, and (b) the hydrodynamic effect on the longer scale.

• 한국식품저장유통학회지
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• 제6권2호
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• pp.153-160
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• 1999

후지 사과의 CA 저장 효과를 생리화학적으로 구명하기 위해 저장 조건에 따른 에틸렌과 이산화탄소 생성 및 이들의 연관성 그리고 과육경도와 과피색의 변화를 조사하였다. 저장 산소농도가 낮을수록 ACC oxidase 활성이 억제되어 내부 에틸렌 농도가 낮게 유지되었다. 특히 1% $O_2$+l% $CO_2$ 조건에서는 내부 에틸렌 농도가 1 ppm 이하로 유지되었으며 저장 후 2$0^{\circ}C$의 air에서도 거의 변화가 없었다. 에틸렌 생성에 고농도 이산화탄소의 영향은 구성 산소농도에 의존적이어서 1% 산소에서는 효과가 없거나 생성 증가 효과를, 3% 산소에서는 생성 억제효과를 나타내었다. 내부 에틸렌 농도와 에틸렌 방출량은 밀접한 상관관계을 나타내었다. 내부 이산화탄소 농도도 이산화탄소 방출량과 밀접한 상관관계를 나타내었으며 저장 산소농도가 가장 낮은 조건인 1% $O_2$+l% $CO_2$에서 가장 낮게 유지되었고 저장 후의 증가폭은 다른 조건들과 차이가 없었다. 저장조건에 따른 에틸렌과 이산화탄소 생성량의 연관성은 CA 저장 사과와 단기간 air 저장 사과에서는 존재하였으나 장기간 air 저장 사과에서는 보이지 않았다. 사과의 과육경도와 과피의 녹색은 에틸렌과 이산화탄소의 생성이 억제된 저장조건일수록 손실이 적었다.

• 천문학회보
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• 제36권2호
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• pp.61.2-61.2
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• 2011

Low-ionization nuclear emission-line regions (LINERs) have been generally regarded to be powered by active galactic nuclei (AGNs), yet still a number of alternative explanations on the origin of LINER emission are suggested; for example, planetary nebulae nuclei of massive stars, supernovae shocks from death of massive stars, and old stellar populations. Interestingly, a majority of recent star formation early-type galaxies (ETGs) in local universe presents such LINER emission lines. Given that situation, revealing the true nature of LINERs is a crucial step to constrain the evolution path to quiescent ETGs. To resolve the issue, we use Keck/LRIS to obtain spatially resolved spectra on a carefully selected ETG. The ETG SDSS J091628.05+420818.7 at redshift z ~ 0.024 shows modest LINER emission line features without any detection of 21 cm radio continuum nor X-ray emission. We perform a stellar continuum subtraction and measure emission line strengths and their uncertainties for each spectrum from five apertures along the slit with size of 1 arcsecond (~0.5 kpc). We find that extended spatial distributions of four emission lines $H{\alpha}$, $H{\beta}$, [OIII]${\lambda}5007$, and [NII]${\lambda}6583$, and they can be explained by central emission blurring effect. We conclude that the emissions seem to be centrally concentrated, indicating the AGN-nature of LINERs.

• 천문학회지
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• 제40권4호
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• pp.83-89
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• 2007

A new type of object called "Very Low Luminosity Objects (VeLLOs)" has been discovered by the Spitzer Space Telescope. VeLLOs might be substellar objects forming by accretion. However, some VeLLOs are associated with strong outflows, indicating the previous existence of massive accretion. The thermal history, which significantly affects the chemistry, between substellar objects with a continuous low accretion rate and objects in a quiescent phase after massive accretion (outburst) must be greatly different. In this study, the chemical evolution has been calculated in an episodic accretion model to show that CO and $N_2H^+$ have a relation different from starless cores or Class 0/I objects. Furthermore, the $CO_2$ ice feature at $15.2{\mu}m$ will be a good tracer of the thermal process in VeLLOs.

• 한국환경농학회지
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• 제16권4호
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• pp.320-326
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• 1997

제초제 imazapyr의 토양환경중 행동을 구명하기 위하여 물리화학적 특성이 상이한 8종의 토양을 이용하여 $^{14}CO_2$로의 무기화 및 흡착 시험을 수행하여 얻은 결과를 요약하면 다음과 같다. 1. 물리화학적 특성이 상이한 8종의 토양중 배양기간 동안 발생된 $^{14}CO_2$의 양은 총 처리 방사능의 약 1.5${\sim}$4.9%로써 토양에 따라 상이한 방출율을 보였다. pH가 낮고 유기물이 많은 토양 C, G 및 H에서는 낮은 $^{14}CO_2$ 방출량을 보인 반면 pH가 높고 유기물이 적은 토양 B와 D에서는 높은 $^{14}CO_2$ 방출율을 보였다. 2. Imazapyr의 흡착실험에서 평형농도 도달시간은 네 토양 모두에서 약 3시간 이었다. 물리화학적 성질이 상이한 토양에서 0.25${\sim}$28.32%의 흡착율을 보였으며, 토양구성 요소중에서, 유기물 함량이 토양에 의한 imazapyr의 흡착에 가장 큰 영향을 미쳤다. Freundlich 흡착상수$(K_f)$는 유기물의 함량이 2.0${\sim}$21.3배 증가함에 따라 5.5${\sim}$25.6배 증가하였다. 그러므로 토양 유기물이 imazapyr의 흡착에 미치는 범위는 점토가 미치는 것보다 더 큼이 분명하다. $K_f$값은 토양 C, D, G 및 H에서 각각 0.44, 0.08, 0.65 및 2.05이었으며, 모든 토양에서 $K_d$와 유사한 값을 보였다.

• Molecules and Cells
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• 제23권3호
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• pp.331-339
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• 2007

It has been suggested that the structure and function of nuclear receptors are evolutionally conserved. Here, we compare the molecular functions of the nile tilapia (Oreochromis niloticus) small heterodimer partner (nSHP/NR0B2) and the Dosage-sensitive sex reversal AHC critical region on X chromosome gene 1 (nDAX-1/NR0B1) with those of human SHP and DAX-1 (hSHP and hDAX-1, respectively). We found that, upon transient cotransfection of human cells, nDAX-1 repressed the activity of tilapia SF-1 (nSF-1) but not that of human SF-1, although the physical interaction with human SF-1 was retained. Similarly, nSHP repressed the activity of nSF-1, whereas hSHP did not, pointing to divergent evolution of SHP/SF-1 in fish and human. We thus propose that the repressive functions of SHP and DAX-1 have been conserved in fish and mammals although with different transcriptional targets and mechanisms. These differences provide new insights into the physiological diversification of atypical orphan nuclear receptors during vertebrate evolution.