Preparation of Manganese/PAN-based Carbon Nanofiber Web by Co-electrospinning

Choi, Gyoung-Rin,Ju, Young-Wan,Jung, Hong-Ryun,Kim, Chan,Yang, Kap-Seung,Lee, Wan-Jin 한국공업화학회 2005 응용화학 Vol.9 No.1

We, in this study, fabricated and applicated MnO₂/carbon fiber nanocomposite web as electrode for supercapacitors prepared by co-electrospinning technique. At first, the PAN-Mn₃O₄ fiber web was prepared by an electrospinning technique to use the mixed solution of both polyacrylonitrile (PAN) in N,N-dimethylformamide (DMF) and 5 ~ 20 wt.% manganese oxide hydrate (Mn₃O₄). The electrospun PAN-Mn₃O₄ fiber web was stabilized at 280℃, and then carbon-Mn₃O₄ nanofiber web was carbonized at 1000℃ in the nitrogen atmosphere. The activated carbon/Mn0₂ electrospun fiber web was synthesized by activating at 800℃ in steam atmosphere. The structure of manganese oxide was changed that Mn₃0₄ was changed Mn0₂ during the carbonization and activation of nanocomposite web. The specific capacitance is increased with increasing Mn₃O₄ contents was 15 wt.%. But the specific capacitance is decreased at 20 wt.% Mn₃O₄/carbon nanofiber. The specific capacitances of 5 wt.% Mn₃O₄/carbon, 10 wt.% Mn₃O₄/carbon, 15 wt.% Mn₃O₄/carbon, 20 wt.% Mn₃O₄/carbon and activated carbon nanofiber or nanofiber composite electrode are 170, 230, 260, 175, 140 F/g, respectively at lmA/Cm². In the case of Mn₃O₄ addition, the specific capacitance is improved due to the synergic effect of pseudocapacitance. But the diameter of carbon fiber increased with the contents of Mn₃O₄ is increased. So the electro double layer capacitance is decreased.

Feasibility of fast non-local means noise reduction algorithm in magnetic resonance imaging using 1.5 and 3.0 T with diffusion-weighted image technique

Choi, Won Ho,Choi, Hye Ran,Seo, Eunsoo,Hwang, Jeewoo,Oh, Heekyung,Kim, Myeong Rae,Han, Su Rin,Kim, Min Seok,Kang, Seong-Hyeon,Lee, Youngjin Elsevier 2019 OPTIK -STUTTGART- Vol.183 No.-

<P><B>Abstract</B></P> <P>Magnetic resonance imaging (MRI) has many advantages and has developed various pulse sequences. In particular, the diffusion weighted image (DWI) technique is widely used because it can acquire images quickly during examination of stroke, through a proper adjustment of the diffusion-weighted gradient b-value. However, a setting with inappropriate b-value causes loss of image signal that increases the influence of noise. Therefore, in this study, we quantitatively evaluated image quality after applying a variety of algorithms to the image acquired by changing the b-value and the main magnetic field in the MRI device. To acquire the image, the phantom was self-produced with an acrylic panel and chicken breast. Wiener filter, total variation (TV), and our proposed fast non-local means (FNLM) noise reduction algorithms were applied to the image. Consequently, the signal intensity at a 3.0 T magnetic field increased by a factor 4.8 compared to a 1.5 T magnetic field. Moreover, the signal-to-noise ratio and contrast-to-noise ratio were highest with the FNLM algorithm, and the values increased by factors of 9.5 and 9.9 with a 1.5 T magnetic field and by factors of 9.9 and 5.0 with a 3.0 T magnetic field compared to the noise image, respectively. The result of time resolution, the Wiener filter appeared the finest value, but had no significant difference compared to FNLM algorithm. In conclusion, our results confirmed that the proposed FNLM noise reduction algorithm can acquire both improved image quality and high processing time in MRI imaging with the DWI technique.</P>

Azobenzene-based chloride transporters with light-controllable activities

Choi, Ye Rin,Kim, Gyu Chan,Jeon, Hae-Geun,Park, Jinhong,Namkung, Wan,Jeong, Kyu-Sung The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.97

<P>Synthetic chloride transporters containing two urea groups linked through a diazobenzene spacer have been prepared and the <I>trans</I>-to-<I>cis</I> isomerization by light stimulation results in dramatic changes in the chloride transport activities across lipid and cell membranes.</P> <P>Graphic Abstract</P><P>Azobenzene-based chloride transporters exhibit photoresponsive transport activities across lipid and plasma membranes. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc07560a'> </P>

Preparation of RuO₂/PAN-Based Carbon Nanofiber Web by Co-electrospinning and Its Electrochemical Property

Choi, Gyoung-Rin,Ju, Young-Wan,Jung, Hong-Ryun,Kim, Chan,Yang, Kap-Seung,Lee, Wan-Jin 한국공업화학회 2005 응용화학 Vol.9 No.1

The RuO₂/carbon fiber nanocomposite webs were prepared by a co-electrospinning technique in order to use as electrodes of supercapacitor. At first, the PAN-RuO2 fiber web was prepared by an electrospinning technique to use the mixed solution of both polyacrylonitrile (PAN) in N,N-dimethylformamide (DMF) and 10 to 20 wt.% ruthenium oxide hydrate (RuO₂). The electrospun PAN-RuO₂ fiber web was stabilized at 280C, and then carbon-RuO₂ nanofiber web was synthesized by activating at 800 C in the steam atmosphere. The specific capacitance is increased with increasing RuO2 contents. But the specific capacitance is decreased at 20 wt.% RuO₂/carbon fiber nanofiber. The specific capacitance of 10 wt.% RuO₂/carbon, 15 wt.% RuO₂/carbon, 20 wt.% RuO₂/carbon and activated carbon nanofiber or nanofiber composite electrode are 365, 461, 390, 140 Fig, respectively at lmA/Cm2. In the case of RuO₂ addition, the specific capacitance is improved due to the synergic effect of pseudocapacitance.

Enzyme-Responsive Procarriers Capable of Transporting Chloride Ions across Lipid and Cellular Membranes

Choi, Ye Rin,Lee, Bom,Park, Jinhong,Namkung, Wan,Jeong, Kyu-Sung American Chemical Society 2016 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.138 No.47

<P>Adopting the concept of procarrier for the first time, we demonstrated the controlled transport of chloride ions across lipid and cellular membranes. Procarriers containing highly hydrophilic appendages were initially inactive due to the lack of their partitioning into lipophilic membranes but were activated to transport chloride ions in the presence of specific enzymes that were able to hydrolyze off the appendages to generate an active carrier under specific conditions. Namely, the procarrier with an ester-bond-linked appendage was most activated by an esterase (PLE) at pH = 7.4, whereas the procarrier with a glycosyl-bond-linked appendage was activated only by a glycosylase (AOG) under slightly acidic conditions (pH = 5.5-6). In addition to controlling chloride transport, hydrophilic appendages greatly increase the water solubility of the procarrier, which may improve the deliverability of a hydrophobic active carrier into a plasma membrane.</P>

Bidirectional Interactions between Green Tea (GT) Polyphenols and Human Gut Bacteria

Choi Se Rin,Lee Hyunji,Singh Digar,Cho Donghyun,Chung Jin-Oh,Roh Jong-Hwa,Kim Wan-Gi,Lee Choong Hwan 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.10

Green tea (GT) polyphenols undergo extensive metabolism within gastrointestinal tract (GIT), where their derivatives compounds potentially modulate the gut microbiome. This biotransformation process involves a cascade of exclusive gut microbial enzymes which chemically modify the GT polyphenols influencing both their bioactivity and bioavailability in host. Herein, we examined the in vitro interactions between 37 different human gut microbiota and the GT polyphenols. UHPLCLTQ-Orbitrap-MS/MS analysis of the culture broth extracts unravel that genera Adlercreutzia, Eggerthella and Lactiplantibacillus plantarum KACC11451 promoted C-ring opening reaction in GT catechins. In addition, L. plantarum also hydrolyzed catechin galloyl esters to produce gallic acid and pyrogallol, and also converted flavonoid glycosides to their aglycone derivatives. Biotransformation of GT polyphenols into derivative compounds enhanced their antioxidant bioactivities in culture broth extracts. Considering the effects of GT polyphenols on specific growth rates of gut bacteria, we noted that GT polyphenols and their derivate compounds inhibited most species in phylum Actinobacteria, Bacteroides, and Firmicutes except genus Lactobacillus. The present study delineates the likely mechanisms involved in the metabolism and bioavailability of GT polyphenols upon exposure to gut microbiota. Further, widening this workflow to understand the metabolism of various other dietary polyphenols can unravel their biotransformation mechanisms and associated functions in human GIT.

Synthetic chloride transporters with the binding mode observed in a ClC chloride channel

Choi, Ye Rin,Chae, Min Kyung,Kim, Dongwook,Lah, Myoung Soo,Jeong, Kyu-Sung The Royal Society of Chemistry 2012 Chemical communications Vol.48 No.83

<P>A series of synthetic molecules bearing the same hydrogen bonding mode observed in StClC were prepared and their transport ability of chloride ion across a lipid membrane was systematically optimized.</P> <P>Graphic Abstract</P><P>Using a series of synthetic molecules with the same hydrogen bonding mode observed in StClC, the transport ability of chloride ion across a lipid membrane has been systematically optimized. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc35743g'> </P>

성수동 붉은 벽돌 건축물에 관한 연구

최예린(Choi, Ye-Rin),이상윤(Lee, Sang-Yun) 대한건축학회 2022 대한건축학회 학술발표대회 논문집 Vol.42 No.2

The purpose of this study was to analyze the housing mobility behavior according to the income change and to predict the probability of upward and downward movements. A binary logit model was used with the data which were obtained by the Korea Research Institute for Human Settlements in 1989. The sample size was 1620 households in Seoul. The results of this study were as follows; the upward movement probability in rental housing or in single housing was higher than that in owned housing or in apartment housing as household income increased.

6·25전쟁기 미군의 포로 정책 전개 양상 -전범조사부와 민간정보교육국의 활동을 중심으로-

최혜린 ( Choi Hye-rin ) 서울대학교 국사학과 2017 韓國史論 Vol.63 No.-

Since the Second World War, war crimes have emerged as a major theme in psychological warfare and propaganda. Therefore the US force tried to highlight the war crimes of the Communist army during the Korean War in order to undermine the morality of them. In October 1950, KWC was established to investigate and prosecute the war crimes of the Communist army. The main investigation target of KWC was POWs held at the United Nations Command(UNC) POW camps. KWC organized an informer system in the UNC POW camps and actively performed war criminal investigation activities using prisoners of the war as informer. The US force also tried to use the prisoners for re-education and psychological warfare against North Korean through systematic educational programs. To do so, they established the CI&E to carry out education programs for POWs in April 1951. In that education programs, many POWs were utilized as a teacher or an assistant in the educational activities. As a result, the POWs were politically divided on these policies and confronted each other. In July 1951, the POWs who participated in the activities of the KWC and CI&E organized a large anti-communist POWs organization. On the other hand, communist POWs began to organize an underground group and developed its power gradually after February 1951. They resisted against the US force and the POWs who had cooperated with them. As a result, conflicts between two North Korean POW groups greatly increased after July 1951 when both groups become well-organized. Due to this problem, the informer system of the KWC was abolished in January 1952, and the education programs of the CI&E was also reduced to be performed only on non-repatriated prisoners determined by repatriation screening.

외식 및 호스피탈리티 분야의 ICT 연구동향에 관한 연구 : 2011-2020 국내 등재 학술지를 중심으로

최세린(Choi, Se-Rin),허경석(Hur, Kyung-Suk) 한국외식경영학회 2021 외식경영연구 Vol.24 No.7

본 연구는 2011년부터 2020년까지 10년간 국내 외식 및 호스피탈리티 분야의 5개 학술 등재지에 게재된 정보통신기술(ICT) 관련 논문 총 409개를 대상으로 하여 연구동향을 파악하고자 내용분석을 하였다. 분석을 통해 ICT 관련 어떠한 주제들이 연구되어 왔는지, ICT 연구의 그간 연구흐름 및 연구시기별 특성을 알아보고자 한다. 연구대상은 데이터를 연구대상으로 한 연구의 비중이 증가했으며, 연구 산업은 관광분야가 가장 많았지만, 여행지를 대상으로 한 연구가 점차 증가했고, 카지노에 대한 연구도 등장했다. 연구분야의 경우는 주로 마케팅이었으며, 세부주제는 온라인 마케팅이 연구되었다. 시기별 연구주제를 보면 2016년 이후에는 그간 주류였던 서비스 품질은 줄어들고, 정보기술 수용 및 데이터 분석은 증가했다. 한편, 연구 핵심어를 분석하면 모바일 서비스에 대한 연구 및 빅데이터 분야가 꾸준히 증가하였다. 마지막으로 연구방법과 분석방법을 분석했다. 본 연구는 이를 통해 국내 외식 및 호스피탈리티 분야의 정보통신기술 관련 연구동향을 이해할 수 있도록 하며, 향후의 연구방향을 시사해 준다. This study conducted content analyses in order to understand the research trend of food service and hospitality top 5 academic journals’ in total 409 ICT related articles which is published for ten years from 2011 to 2020. Through the analyses, this study aims to investigate what ICT-related topics have been studied, what the current research flow of ICT research is, and what the characteristics of each period of research are. As a result of the study, the rate of research using data has increased. Although tourism turn out to be the largest research industry, research on tourist destinations gradually increased, and research on casinos newly appeared. The research field was mainly about marketing, and the detailed research topics were online marketing related topics. When it comes to research topics by period, after 2016, the service quality, which had been the mainstream, decreased, and the acceptance of ICT and data analysis increased. Meanwhile, research on mobile services and big data have steadily increased according to research keyword analysis. Finally, the research method and analysis method were analyzed. Based on the implications from the results, this study provides ideas about ICT future research directions.