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Tension assisted metal transfer of graphene for Schottky diodes onto wafer scale substrates
Lee, Jooho,Lee, Su Chan,Kim, Yongsung,Heo, Jinseong,Lee, Kiyoung,Lee, Dongwook,Kim, Jaekwan,Lee, Sunghee,Lee, Chang Seung,Nam, Min Sik,Jun, Seong Chan IOP 2016 Nanotechnology Vol.27 No.7
<P>We developed an effective graphene transfer method for graphene/silicon Schottky diodes on a wafer as large as 6 inches. Graphene grown on a large scale substrate was passivated and sealed with a gold layer, protecting graphene from any possible contaminant and keeping good electrical contact. The Au/graphene was transferred by the tension-assisted transfer process without polymer residues. The gold film itself was used directly as the electrodes of a Schottky diode. We demonstrated wafer-scale integration of graphene/silicon Schottky diode using the proposed transfer process. The transmission electron microscopy analysis and relatively low ideality factor of the diodes indicated fewer defects on the interface than those obtained using the conventional poly(methyl methacrylate)-assisted transfer method. We further demonstrated gas sensors as an application of graphene Schottky diodes.</P>
Lee, Sunghee,Cantarel, Brandi,Henrissat, Bernard,Gevers, Dirk,Birren, Bruce W,Huttenhower, Curtis,Ko, GwangPyo Nature Publishing Group 2014 The ISME journal Vol.8 No.3
<P>Glycoside hydrolases (GHs), the enzymes that breakdown complex carbohydrates, are a highly diversified class of key enzymes associated with the gut microbiota and its metabolic functions. To learn more about the diversity of GHs and their potential role in a variety of gut microbiomes, we used a combination of 16S, metagenomic and targeted amplicon sequencing data to study one of these enzyme families in detail. Specifically, we employed a functional gene-targeted metagenomic approach to the 1-4-α-glucan-branching enzyme (gBE) gene in the gut microbiomes of four host species (human, chicken, cow and pig). The characteristics of operational taxonomic units (OTUs) and operational glucan-branching units (OGBUs) were distinctive in each of hosts. Human and pig were most similar in OTUs profiles while maintaining distinct OGBU profiles. Interestingly, the phylogenetic profiles identified from 16S and gBE gene sequences differed, suggesting the presence of different gBE genes in the same OTU across different vertebrate hosts. Our data suggest that gene-targeted metagenomic analysis is useful for an in-depth understanding of the diversity of a particular gene of interest. Specific carbohydrate metabolic genes appear to be carried by distinct OTUs in different individual hosts and among different vertebrate species' microbiomes, the characteristics of which differ according to host genetic background and/or diet.</P>
Crack-Release Transfer Method of Wafer-Scale Grown Graphene Onto Large-Area Substrates
Lee, Jooho,Kim, Yongsung,Shin, Hyeon-Jin,Lee, ChangSeung,Lee, Dongwook,Lee, Sunghee,Moon, Chang-Yul,Lee, Su Chan,Kim, Sun Jun,Ji, Jae Hoon,Yoon, Hyong Seo,Jun, Seong Chan American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.15
<P>We developed a crack-release graphene transfer technique for opening up possibilities for the fabrication of graphene-based devices. Graphene film grown on metal catalysts/SiO<SUB>2</SUB>/Si wafer should be scathelessly peeled for sequent transferring to a target substrate. However, when the graphene is grown on the metal catalyst on a silicon substrate, there is a large tensile stress resulting from the difference of the coefficient of thermal expansion in the catalyst and silicon. The conventional methods of detaching graphene from metal catalysts were found to induce considerable mechanical damage on graphene films during separation processes including metal wet etching. Here we report a new technique wherein bubbles generated by electrolysis reaction separate thin metal catalysts from the SiO<SUB>2</SUB>/Si wafer. The dry attachment of graphene to the target wafer was processed utilizing a wafer to wafer bonding technique in a vacuum. We measured the microscopic image, Raman spectra, and electrical properties of the transferred graphene. The optical and electrical properties of the graphene transferred by the bubbles/dry method are better than those of the graphene obtained by mechanical/wet transfer.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-15/am502565z/production/images/medium/am-2014-02565z_0005.gif'></P>
Adaptive Rate Control Scheme for Streaming-based Content Sharing Service
( Sunghee Lee ),( Kwangsue Chung ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.4
This paper presents an adaptive rate control scheme for streaming-based content sharing service. This scheme delivers multimedia contents from a user device to another device or seamlessly redirects streaming service across heterogeneous user devices. In the proposed scheme, a streaming server adjusts video quality level according to the network and client status. Our scheme is different from other rate control schemes, because the video quality at the server is decided not only based on the available bandwidth, but also based on the device characteristics and bandwidth requirement at the access network. We also propose a bandwidth estimation method to achieve more equitable bandwidth allocations among streaming flows competing for the same narrow link with different Round Trip Times (RTTs). Through the simulation, we prove that our scheme improves the network stability and the quality of streaming service by appropriately adjusting the quality of the video stream. The simulation results also demonstrate the ability of the proposed scheme in ensuring RTT-fairness while remaining throughput efficient.
Lee, Changyeol,Kim, Soonok,Li, Wei,Bang, Sunghee,Lee, Hanna,Lee, Hyun-Jung,Noh, Eun-Young,Park, Jung-Eun,Bang, Woo Young,Shim, Sang Hee Springer Science and Business Media LLC 2017 Journal of antibiotics Vol.70 No.6
<P>Endophytes, important plant-associated mycobionts, have attracted a great deal of attention because of their bioactive secondary metabolites. Even though halophytes have been reported to overcome salt stress via associations with their endophytes, few studies have investigated the metabolites produced by the endophytes from halophytes. In this study, a dark septate endophytic fungal strain (JS0464), identified as Gaeumannomyces sp. by ITS sequencing, was isolated from the rhizome of a halophyte, Phragmites communis, in Suncheon bay, South Korea. This strain was cultured on a large scale and extracted with ethyl acetate. Chemical investigations of extracts of JS0464 led to the isolation of two glycosylated dialkylresorcinol derivatives (1-2), an anthraquinone derivative (3) and eight known compounds (4-11), which were identified by spectroscopic analyses incorporating one-dimensional/2D NMR and MS. Nine compounds showed significant nitric oxide reduction activity in lipopolysaccharide-stimulated microglia BV-2 cells, seven of which did not impair cell viability. The results suggest that endophytes from the halophytes could be potential resources for bioactive natural products.</P>
Sunghee Lee,Minsoo Shin,Seo Hee Kim,Seong Pyo Kim,Hyung-Jin Yoon,Yangsoon Park,Jaemoon Koh,Seak Hee Oh,Jae Sung Ko,Jin Soo Moon,Kyung Mo Kim 대한소아소화기영양학회 2024 Pediatric gastroenterology, hepatology & nutrition Vol.27 No.4
Purpose: Few studies have reported the prevalence of inflammatory bowel disease unclassified (IBDU) among Korean pediatric IBD (PIBD) population. To address this gap, we used two tertiary centers and nationwide population-based healthcare administrative data to estimate the prevalence of Korean pediatric IBDU at the time of diagnosis. Methods: We identified 136 patients aged 2–17 years with newly diagnosed IBD (94 Crohn’s disease [CD] and 42 ulcerative colitis [UC]) from two tertiary centers in Korea between 2005 and 2017. We reclassified these 136 patients using the revised Porto criteria. To estimate the population-based prevalence, we analyzed Korean administrative healthcare data between 2005 and 2016, which revealed 3,650 IBD patients, including 2,538 CD and 1,112 UC. By extrapolating the reclassified results to a population-based dataset, we estimated the prevalence of PIBD subtypes. Results: Among the 94 CD, the original diagnosis remained unchanged in 93 (98.9%), while the diagnosis of one (1.1%) patient was changed to IBDU. Among the 42 UC, the original diagnosis remained unchanged in 13 (31.0%), while the diagnoses in 11 (26.2%), 17 (40.5%), and one (2.4%) patient changed to atypical UC, IBDU, and CD, respectively. The estimated prevalences of CD, UC, atypical UC, and IBDU in the Korean population were 69.5%, 9.4%, 8.0%, and 13.1%, respectively. Conclusion: This study is the first in Korea to estimate the prevalence of pediatric IBDU. This prevalence (13.1%) aligns with findings from Western studies. Large-scale prospective multicenter studies on PIBDU are required to examine the clinical features and outcomes of this condition.
Comparison of the Gut Microbiotas of Healthy Adult Twins Living in South Korea and the United States
Lee, Sunghee,Sung, Joohon,Lee, JungEun,Ko, GwangPyo American Society for Microbiology 2011 Applied and environmental microbiology Vol.77 No.20
<B>ABSTRACT</B><P>We compared the composition of the fecal microbiotas of Korean and U.S. adult twins. Our data indicated that the gut microbiota shows some signature of biogeography, potentially mediated by differences in diet and/or other environmental factors; however, these regional differences may be masked by other phenotypic variations, such as obesity.</P>
( Sunghee Lee ),( Kyung Min Park ),( Jongbae Park ) 한국모자보건학회 2007 한국모자보건학회 학술대회 연제집 Vol.2007 No.2
Background: As more females smoke, women’s health is in danger. New smoking cessation programs incorporating the special needs of female populations is awaited. Self- performed hand massage with aroma oil was suggested to be promisingly effective to help stop smoking, hence rigorous testing is warranted. Purpose: To test the effects of self-hand massage with aroma oil on the smoking habit and the depression of female college student smokers. Method: Fifty-one female college student smokers who wished to stop smoking took part in the study. The participants were randomly allocated to either an educational program on smoking cessation only, or self- hand massage with aroma oil for 4 weeks in addition to the educational program. The aroma oil was comprised of Lavender, Chamomile, and Bergamot essence oil. Result: The self-hand massage with aroma oil group showed significant changes on daily cigarette use and depression. Conclusion: It is promising that self-hand massage with aroma oil can be an effective adjunctive to reduce the use of daily cigarettes, and improve the depression of female college student smokers who attempted to stop smoking.
A Study on the Formation Mechanism of the Interfacial Layer Between Solid CaO and Molten Iron Alloys
Sunghee Lee,Dong Joon Min 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.1
The present study aims to clarify the formation mechanism of the interfacial layer between solid CaO and molten ironthrough SEM–EDS analysis. The interfacial layer formed between CaO and molten iron is observed by SEM–EDS fordifferent compositions of molten iron (CaO/Fe–C–S interface: CaS layer; CaO/Fe–C–Si–S interface: CaS and Ca2SiO4layers; CaO/Fe–C–Si interface: no interfacial layer; CaO/Fe–S–Si interface: Ca2SiO4and CaS layers). The effect of S andSi concentrations on layer formation is discussed using the following proposed mechanism. * Dong Joon Minchemical@yonsei.ac.kr1 Department of Material Science and Engineering, YonseiUniversity, Seoul 038722, Republic of KoreaIn the case of the Fe–C–Si–Al–S/CaO interface, CaS and Ca3Al2O6layers are observed. The formation mechanism of areaction layer for Al-containing iron melts is also proposed as below. CaO(s) + S = CaS(s) +12O22CaO(s) + Si + O2 = Ca2SiO4(s)CaO(s) + S = CaS(s) +12O23CaO(s) + 2Al +32O2 = Ca3Al2O6(s)