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Kim, Yeonwoo,Yang, Sena,Jeon, Eun Hee,Baik, Jaeyoon,Kim, Namdong,Kim, Hyun Sung,Lee, Hangil Springer US 2016 NANOSCALE RESEARCH LETTERS Vol.11 No.1
<P>To design a high-performance photocatalytic system with TiO<SUB>2</SUB>, it is necessary to reduce the bandgap and enhance the absorption efficiency. The reduction of the bandgap to the visible range was investigated with reference to the surface distortion of anatase TiO<SUB>2</SUB> nanoparticles induced by varying Fe doping concentrations. Fe-doped TiO<SUB>2</SUB> nanoparticles (Fe@TiO<SUB>2</SUB>) were synthesized by a hydrothermal method and analyzed by various surface analysis techniques such as transmission electron microscopy, Raman spectroscopy, X-ray diffraction, scanning transmission X-ray microscopy, and high-resolution photoemission spectroscopy. We observed that Fe doping over 5 wt.% gave rise to a distorted structure, i.e., Fe<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>9</SUB>, indicating numerous Ti<SUP>3+</SUP> and oxygen-vacancy sites. The Ti<SUP>3+</SUP> sites act as electron trap sites to deliver the electron to O<SUB>2</SUB> as well as introduce the dopant level inside the bandgap, resulting in a significant increase in the photocatalytic oxidation reaction of thiol (–SH) of 2-aminothiophenol to sulfonic acid (–SO<SUB>3</SUB>H) under ultraviolet and visible light illumination.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s11671-016-1263-6) contains supplementary material, which is available to authorized users.</P>
실시간 기상 빅데이터를 활용한 홍수 재난안전 시스템 설계 및 구현
김연우(Yeonwoo Kim),김병훈(Byounghoon Kim),고건식(Geonsik Ko),최민웅(Minwoong Choi),송희섭(Heesub Song),김기훈(Gihoon Kim),유승훈(Seunghun Yoo),임종태(Jongtae Lim),복경수(Kyungsoo Bok),유재수(Jaesoo Yoo) 한국콘텐츠학회 2017 한국콘텐츠학회논문지 Vol.17 No.1
최근 빅데이터 분석 기술을 통해 새로운 정보를 도출하기 위한 분석 기법들과 이를 활용한 다양한 서비스들이 개발되고 있다. 그 중에서도 재난안전은 생활에 밀접한 서비스로 가장 중요하게 연구되고 있다. 본 논문에서는 실시간 기상 빅데이터 분석을 이용한 홍수 재난안전 시스템을 설계하고 구현한다. 제안하는 시스템은 실시간으로 수집되는 방대한 양의 정보를 검색하고 처리한다. 더불어 실시간 정보와 과거에 수집된 정보들을 결합하여 위험요인을 분석하고, 예측 정보를 사용자에게 제공한다. 또한, 제안하는 시스템은 사용자 메시지 및 뉴스와 같은 실시간 정보와 태풍 · 홍수 등으로 인한 하천 범람 등과 같은 재난 위험요인을 분석한 위험 예측 정보를 제공한다. 따라서 사용자는 제안하는 시스템을 통해 향후 발생 가능성이 있는 재난안전 사고 위험에 대비할 수 있다. Recently, analysis techniques to extract new meanings using big data analysis and various services using them have been developed. A disaster safety service among such services has been paid attention as the most important service. In this paper, we design and implement a flood disaster safety system using real time weather big data. The proposed system retrieves and processes vast amounts of information being collected in real time. In addition, it analyzes risk factors by aggregating the collected real time and past data and then provides users with prediction information. The proposed system also provides users with the risk prediction information by processing real time data such as user messages and news, and by analyzing disaster risk factors such a typhoon and a flood. As a result, users can prepare for potential disaster safety risks through the proposed system.
Kim, Jinyeong,Kim, Seungbum,Yoon, Sangyoung,Hong, Eunsoo,Ryu, Yeonwoo Springer International 2015 Applied microbiology and biotechnology Vol.99 No.15
<P>Thermostable esterases have potential applications in various biotechnology industries because of their resistance to high temperature and organic solvents. In a previous study, we isolated an esterase from Archaeoglobus fulgidus DSM 4304 (Est-AF), which showed high thermostability but low enantioselectivity toward (S)-ketoprofen ethyl ester. (R)-ketoprofenor (S)-ketoprofenis produced by esterase hydrolysis of the ester bond of (R,S)-ketoprofen ethyl ester and (S)-ketoprofen has better pharmaceutical activity and lower side effects than (R)-ketoprofen. Therefore, we have generated mutants of Est-AF that retained high thermostability whilst improving enantioselectivity. A library of Est-AF mutants was created by error-prone polymerase chain reaction, and mutants with improved enantioselectivity were isolated by site-saturation mutagenesis. The regions of Est-AF containing amino acid mutations were analyzed by homology modeling of its three-dimensional structure, and structure-based explanations for the changes in enantioselectivity are proposed. Finally, we isolated two mutants showing improved enantioselectivity over Est-AF (ee%?=?-16.2??0.2 and E?=?0.7??0.0): V138G (ee%?=?35.9??1.0 and E?=?3.0??0.1) and V138G/L200R (ee%?=?89.2??0.2 and E?=?19.5??0.5). We also investigated various characteristics of these mutants and found that the mutants showed similar thermostability and resistance to additives or organic solvents to Est-AF, without a significant trade-off between activity and stability.</P>
Kim, Jinyeong,Kim, Seul I.,Hong, Eunsoo,Ryu, Yeonwoo Elsevier 2016 Protein expression and purification Vol.127 No.-
<P><B>Abstract</B></P> <P>Heterologous proteins expressed in bacteria are used for numerous biotechnological applications. <I>Escherichia coli</I> is the most commonly used host for heterologous protein expression because of its many advantages. Researchers have been studying proteins from extremophiles heterologously expressed in <I>E. coli</I> because the proteins of extremophiles are strongly resistant to extreme conditions. In a previous study, a thermostable esterase Est-AF was isolated from <I>Archaeoglobus fulgidus</I> and expressed in <I>E. coli</I>. However, further studies of Est-AF were difficult owing to its low expression levels in <I>E. coli</I>. In this study, we used various strategies, such as changing the expression vector and host strain, codon optimization, and optimization of induction conditions, to increase the expression of Est-AF. Through codon optimization and by changing the vector and host strain, Est-AF expression was increased from 31.50 ± 0.35 mg/L to 61.75 ± 0.28 mg/L. The optimized expression system consisted of a codon-optimized <I>Est-AF</I> gene in a pET28a(+)-based expression plasmid in <I>E. coli</I> Rosetta cells. The expression level was further increased by optimizing the induction conditions. The optimized conditions were induction with 0.4 mM isopropyl-b-<SMALL>D</SMALL>-1-thiogalactoside (IPTG) at 37 °C for 5 h. Under these conditions, the expression level of Est-AF was increased from 31.5 ± 0.35 mg/L to 119.52 ± 0.34 mg/L.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The thermostable esterase Est-AF is expressed at low levels in <I>Escherichia coli.</I> </LI> <LI> The expression of Est-AF in <I>E. coli</I> was increased by various strategies. </LI> <LI> The expression of Est-AF was increased from 31.50 ± 0.35 to 119.52 ± 0.34 mg/L. </LI> <LI> The enzyme activity of Est-AF was maintained. </LI> </UL> </P>
Yeonwoo Kim(김연우),Sungmin Hwang(황성민),Byung-Gook Park(박병국) 대한전자공학회 2020 대한전자공학회 학술대회 Vol.2020 No.11
In this paper, we propose a neuron circuit with a virtually grounded integrator as a solution for nonlinearity problem in synaptic current summation. To evaluate the performance of the proposed circuit, a hardware-based MNIST pattern recognition simulation was conducted based on the measurement data of fabricated Ni / SiNx / n+-Si RRAM. Simulation results suggest that the proposed circuit enhanced the performance of input-weight product summation.
A disturbed resource reservation structure for mobility and QoS support in WiMedia networks
Kim, Jin-Woo,Hur, Kyeong,Kim, Jong-Ok,Eom, Doo-Seop,Lee, Yeonwoo IEEE 2010 IEEE transactions on consumer electronics Vol.56 No.2
<P>A Distributed Medium Access Control (DMAC) protocol has been proposed to support high-rate Wireless Personal Area Networks (HR-WPANs) by the WiMedia Alliance. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However, since each device's mobility perspective in multi-hop environment has not been taken into account in the current WiMedia D-MAC, it may cause a 'mobile' hidden node problem. In addition, once a DRP conflict occurs due to the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs, while the other DRP reservations must be terminated and DRP negotiations for them have to be re-started although only a few MASs are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mechanism to prevent and resolve multi-hop range DRP conflicts due to each device's mobility in D-MAC environment(1).</P>