Probing Tidal Field Strength of Virgo Cluster Galaxies

Hyein Yoon,Aeree Chung 한국천문학회 2011 天文學會報 Vol.36 No.2

PRE-PROCESSING OF GALAXIES IN THE FILAMENTS AROUND THE VIRGO CLUSTER

YOON, HYEIN,CHUNG, AEREE,SENGUPTA, CHANDREYEE,WONG, O. IVY,BUREAU, MARTIN,REY, SOO-CHANG,VAN GORKOM, J.H. The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

Galaxies can be "pre-processed" in the low-density outskirts by ambient medium in the filaments or tidal interactions with other galaxies while falling into the cluster. In order to probe how early on and by which mechanisms galaxies can be affected before they enter high-density cluster environments, we are carrying out an atomic hydrogen ($H\small{I}$) imaging study of a sample of galaxies selected from three filamentary structures around the Virgo cluster. Our sample consists of 14 late-type galaxies, which are potentially interacting with their surroundings. The $H\small{I}$ observations have been done using the Westerbork Synthesis Radio Telescope, the Giant Metrewave Radio Telescope, and the Jansky Very Large Array with column density sensitivity of ${\approx}3-5{\times}10^{19}cm^{-2}$ in $3{\sigma}$ per channel, which is low enough to detect faint $H\small{I}$ features in the outer disks of galaxies. In this work, we present the Hi data of two galaxies that were observed with GMRT. We examine the $H\small{I}$ morphology and kinematics to find the evidence for gas-gas and/or tidal interactions, and discuss which mechanism(s) could be responsible for pre-processing in these cases.

Ammonia Removal Model Based on the Equilibrium and Mass Transfer Principles

Yoon, Hyein,Lim, Ji-Hye,Chung, Hyung-Keun Korean Chemical Society 2008 Bulletin of the Korean Chemical Society Vol.29 No.3

In air stripping of ammonia from the aqueous solution, a new removal model was presented considering the equilibrium principles for the ammonia in aqueous solution and between the aqueous and air phase. The effects of pH, temperature and airflow rate on the ammonia removal were evaluated with the model. In addition, the saturation degree of ammonia in air was defined and used to evaluate the effect of each experimental factor on the removal rate. As pH (8.9 to 11.9) or temperature (20 to 50 oC) was increased, the overall removal rate constants in all cases were appeared to be increased. Our presented model shows that the degrees of saturation were about the same (0.45) in all cases when the airflow condition remains the same. This result indicates that the effect of pH and temperature were directly taken into consideration in the model equation. As the airflow increases, the overall removal rate constants were increased in all cases as expected. However, the saturation degree was exponentially decreased with increasing the airflow rate in the air phase (or above-surface) aeration. In the subsurface aeration the saturation degree remains a constant value of 0.65 even though the airflow rate was increased. These results indicate that the degree of saturation is affected mainly by the turbulence of the aqueous solution and remains the same above a certain airflow rate.

Diagnostics to Probe Environmental Effects on Late-type Galaxies in the Virgo Cluster

Hyein Yoon,Aeree Chung 한국천문학회 2012 天文學會報 Vol.37 No.2

A Phase-space View of Environmentally Driven Processes in the Virgo Cluster

Hyein Yoon,Aeree Chung,Rory Smith,Yara L. Jaffé 한국천문학회 2016 天文學會報 Vol.41 No.1

The WSRT HI Imaging Study of Gas-rich Galaxies in the Outskirts of the Virgo Cluster

Hyein Yoon,Aeree Chung,Chandreyee Sengupta,O. Ivy Wong,Martin Bureau,Soo-Chang Rey,J. H. van Gorkom 한국천문학회 2015 天文學會報 Vol.40 No.1

Ammonia Removal Model Based on the Equilibrium and Mass Transfer Principles

Hyein Yoon,정형근,Ji-Hye Lim 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.3

In air stripping of ammonia from the aqueous solution, a new removal model was presented considering the equilibrium principles for the ammonia in aqueous solution and between the aqueous and air phase. The effects of pH, temperature and airflow rate on the ammonia removal were evaluated with the model. In addition, the saturation degree of ammonia in air was defined and used to evaluate the effect of each experimental factor on the removal rate. As pH (8.9 to 11.9) or temperature (20 to 50 ˚C) was increased, the overall removal rate constants in all cases were appeared to be increased. Our presented model shows that the degrees of saturation were about the same (0.45) in all cases when the airflow condition remains the same. This result indicates that the effect of pH and temperature were directly taken into consideration in the model equation. As the airflow increases, the overall removal rate constants were increased in all cases as expected. However, the saturation degree was exponentially decreased with increasing the airflow rate in the air phase (or above-surface) aeration. In the subsurface aeration the saturation degree remains a constant value of 0.65 even though the airflow rate was increased. These results indicate that the degree of saturation is affected mainly by the turbulence of the aqueous solution and remains the same above a certain airflow rate.

A History of H i Stripping in Virgo: A Phase-space View of VIVA Galaxies

Yoon, Hyein,Chung, Aeree,Smith, Rory,Jaffé,, Yara L. American Astronomical Society 2017 The Astrophysical Journal Vol.838 No.2

<P>We investigate the orbital histories of Virgo galaxies at various stages of HI gas stripping. In particular, we compare the location of galaxies with different HI morphology in phase space. This method is a great tool for tracing the gas stripping histories of galaxies as they fall into the cluster. Most galaxies at the early stage of HI stripping are found in the first infall region of Virgo, while galaxies undergoing active HI stripping mostly appear to be falling in or moving out near the cluster core for the first time. Galaxies with severely stripped, yet symmetric, HI disks are found in one of two locations. Some are deep inside the cluster, but others are found in the cluster outskirts with low orbital velocities. We suggest that the latter group of galaxies belong to a 'backsplash' population. These present the clearest candidates for backsplashed galaxies observationally identified to date. We further investigate the distribution of a large sample of HI-detected galaxies toward Virgo in phase space, confirming that most galaxies are stripped of their gas as they settle into the gravitational potential of the cluster. In addition, we discuss the impact of tidal interactions between galaxies and group preprocessing on the HI properties of the cluster galaxies, and link the associated star formation evolution to the stripping sequence of cluster galaxies.</P>

FLASH: The First Large Absorption Survey in HI with the Australian Square Kilometre Array Pathfinder

Hyein Yoon,Elaine Sadler,James Allison,Vanessa Moss,Elizabeth Mahony,Matthew Whiting,Renzhi Su 한국천문학회 2020 天文學會報 Vol.45 No.1

젓갈에서 분리한 락토바실러스 파라카제이 GLU70 균주의 생화학적 특성 및 글루텐 분해능

박혜인(Hyein Park),윤슬기(Seul Gi Yoon),장준호(Junho Jang),변지영(Ji Young Byun),윤복근(Bok Kun Yoon) 한국식품과학회 2022 한국식품과학회지 Vol.54 No.2

본 연구에서는 글루텐 분해능을 가지는 유산균을 선별하기 위해 전통식품인 젓갈을 이용하였다. 선별된 균주는 API, 16S rRNA sequencing과 현미경을 통해 간균의 형태를 갖는 Lactobacillus paracasei로 동정되었고 이를 GLU70으로 명명하기로 하였다. MRS 배지에서 GLU70의 생육특성을 조사한 결과, 6시간부터 12시간까지 대수기이며 12시간 이후부터 정지기임을 확인하였다. 이렇게 동정된 GLU70을 글루텐이 함유된 MRS배지에서 시간별로 배양하였을 때 대수기인 12시간 이후부터 24시간 이전까지 글루텐 분해가 가속화되었고, 48시간에서 최대 45% 정도의 분해율을 나타내었다. 또한 GLU70이 유산균으로서 적합하기 위해서 가져야 하는 내산성, 내담즙성, 내열성에 대한 분석을 실시하였다. 많은 연구에서 Lactobacillus 종이 pH 2.5 이상에서는 균의 생존율이 높았지만, 그 이하에서는 거의 생존하지 않는다고 보고하고 있다(Shin 등, 1999). 이에 따라 분리한 GLU70에서도 유사하게 pH 2.0에서는 균이 사멸하였고 pH 3.0부터 약 84%의 생존율을 보였고 많은 연구들과 유사한 결과를 가지는 것을 통해 우수한 내산성을 가지는 것을 확인하였다. 내담즙성의 경우 oxgall이 0.3% 함유된 배지에서 성장할 수 있을 정도의 내성을 가져야 한다는 연구결과와 비교하였을 때 GLU70은 담즙에 대하여 매우 강한 내성을 가지고 있다고 보기는 어렵다. 또한 내열성에 대한 연구결과에서는 50℃ 이상의 온도에서는 사멸하였으나 30℃에서는 높은 생존율을 나타냈다. 또한 분리된 GLU70이 실제 밀가루 반죽에서 감소하는 글루텐 함량을 분석하였을 때 12 h 배양한 배양상등액을 넣어 25℃에서 24 h 동안 발효한 밀가루 반죽에서 가장 높은 분해력을 확인하였다. 또한 밀가루 반죽의 발효 온도에 따른 글루텐 분해율을 타 균주와 비교하여 GLU70의 우수성을 판단하고자 하였다. GRAS 인정 유산균 11종과 GLU70을 각각 밀가루 반죽에 넣은 후 25℃와 35℃에서 발효하였다. 그 결과 GLU70이 타 균주들과 비교하였을 때 모든 온도에서 반죽이 흘러내리는 등의 이상현상 없이 50% 이상의 매우 높은 글루텐 분해율을 보였다. 이를 통해 GLU70이 향후 식품 산업에 다양한 활용 가능성을 지니며 글루텐 저감화 밀가루 제조 등에 적용하기에 적합하다고 제시된다. Gluten is an insoluble protein present in cereals such as wheat. Gluten consumed through food is not digested and accumulates in the body; this has been linked to digestive discomfort, irritation, and various digestive disorders, including intestinal inflammation. In this study, the Lactobacillus paracasei strain GLU70, which exhibits a gluten-degrading ability, was isolated from salted seafood. At a pH of 3.0, GLU70 showed a survival rate of approximately 84%, and at 0.3% oxgall, it showed a survival rate of approximately 53%. When the culture supernatant collected after 12 h of incubation was added to flour dough, approximately 50% gluten degradation was observed. Moreover, among several probiotic isolates exhibiting proteolytic activity selected to assess the gluten-degrading ability, GLU70 showed superior results regardless of the dough fermentation temperature. Although further research is required, GLU70 is expected to be of value in manufacturing gluten-reduced products and the food industry as an ingredient or additive.