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Eom, Yong Hwan,Yoo, Jin Woo,Hong, Sung Bin,Kim, Min Soo Elsevier 2019 ENERGY Vol.187 No.-
<P><B>Abstract</B></P> <P>In heat pumps, refrigerant leakage is one of the frequent faults. Since the systems have the best performance at the optimal charge, it is essential to predict refrigerant charge amount. Hence, the refrigerant charge fault detection (RCFD) methods have been developed by researchers. Due to improvements in computing speed and big-data, data-driven techniques such as artificial neural networks (ANNs) have been highlighted recently. However, most existing ANN-based RCFD methods use low-performance shallow neural networks (SNNs) and require the features extracted by experts’ experiences. Also, they have some critical limitations. First, they cannot provide quantitative information on recharge amount due to a simple classification such as undercharge or overcharge. Second, many ANN-based RCFD methods can be used in one operation mode (cooling or heating mode). To improve the limitations, a novel RCFD strategy based on convolutional neural networks (CNNs) was suggested. Two prediction models using classification and regression can predict the quantitative refrigerant amount in both cooling and heating mode with a single model. The mean accuracy of the CNN-based classification model was 99.9% for the learned cases. Also, the CNN-based regression model showed the excellent prediction performance with root-mean-square (RMS) error of 3.1% including the untrained refrigerant charge amount data.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two quantitative refrigerant charge fault detection (RCFD) methods using CNN for heat pumps. </LI> <LI> The CNN-based RCFD classification model achieved the prediction accuracy of 99.9%. </LI> <LI> In the CNN-based regression model, the prediction error was within 3.1% of the RMS error. </LI> <LI> New methods can predict the refrigerant charge amount in both cooling and heating mode. </LI> </UL> </P>
Eom, Taeyong,Choi, Seol,Choi, Byung Joon,Lee, Min Hwan,Gwon, Taehong,Rha, Sang Ho,Lee, Woongkyu,Kim, Moo-Sung,Xiao, Manchao,Buchanan, Iain,Cho, Deok-Yong,Hwang, Cheol Seong American Chemical Society 2012 Chemistry of materials Vol.24 No.11
<P>Phase change random access memory appears to be the strongest candidate for next-generation high density nonvolatile memory. The fabrication of ultrahigh density phase change memory (≫1 Gb) depends heavily on the thin film growth technique for the phase changing chalcogenide material, most typically containing Ge, Sb and Te (Ge–Sb–Te). Atomic layer deposition (ALD) at low temperatures is the most preferred growth method for depositing such complex materials over surfaces possessing extreme topology. In this study, [(CH<SUB>3</SUB>)<SUB>3</SUB>Si]<SUB>2</SUB>Te and stable alkoxy-Ge (Ge(OCH<SUB>3</SUB>)<SUB>4</SUB>) and alkoxy-Sb (Sb(OC<SUB>2</SUB>H<SUB>5</SUB>)<SUB>3</SUB>) metal–organic precursors were used to deposit various layers with compositions lying on the GeTe<SUB>2</SUB>–Sb<SUB>2</SUB>Te<SUB>3</SUB> tie lines at a substrate temperature as low as 70 °C using a thermal ALD process. The adsorption of Ge precursor was proven to be a physisorption type while other precursors showed a chemisorption behavior. However, the adsorption of Ge precursor was still self-regulated, and the facile ALD of the pseudobinary solid solutions with composition (GeTe<SUB>2</SUB>)<SUB>(1-x)</SUB>(Sb<SUB>2</SUB>Te<SUB>3</SUB>)<SUB><I>x</I></SUB> were achieved. This chemistry-specific ALD process was quite robust against process variations, allowing highly conformal, smooth, and reproducible film growth over a contact hole structure with an extreme geometry. The detailed ALD behavior of binary compounds and incorporation behaviors of the binary compounds in pseudobinary solid solutions were studied in detail. This new composition material showed reliable phase change and accompanying resistance switching behavior, which were slightly better than the standard Ge<SUB>2</SUB>Sb<SUB>2</SUB>Te<SUB>5</SUB> material in the nanoscale. The local chemical environment was similar to that of conventional Ge<SUB>2</SUB>Sb<SUB>2</SUB>Te<SUB>5</SUB> materials.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2012/cmatex.2012.24.issue-11/cm300539a/production/images/medium/cm-2012-00539a_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm300539a'>ACS Electronic Supporting Info</A></P>
Eom, Seung Hun,Kim, Hee Su,Do, Hee Jin,Lee, Un-Hak,Wibowo, Febrian Tri Adhi,Hwang, Do-Hoon,Yoon, Sung Cheol,Jung, In Hwan Elsevier 2018 Dyes and pigments Vol.156 No.-
<P><B>Abstract</B></P> <P>Perylene diimide (PDI) based high bandgap acceptors, DTBTP, DTF2BTP, and DTF2TZP, are synthesized for use in fullerene-free organic solar cells. The two PDI rings are connected to the end of the n-type core, forming a PDI-n-type core-PDI structure. Several n-type core materials, 4,7-dithieno-2,1,3-benzothiadiazole (DTBT), 5,6-difluoro-4,7-dithieno-2,1,3-benzothiadiazole (DTF2BT), and 4,6-difluoro-2H-benzo[d][1,2,3]triazole (DTF2TZ), are incorporated in the PDI acceptors and the n-type core effect on photovoltaic properties is studies. The introduction of alkyl side chains onto the core structure weakened the intermolecular interaction, whereas fluorination of the core structure improved the backbone planarity and intermolecular ordering. DTF2BTP having a planar core structure without bulky alkyl chains yielded the best power conversion efficiency, 4.41%, when mixed with PTB7-Th donor. The n-type core structure was beneficial in terms of increasing the electron accepting properties and the absorption in the high bandgap region of non-fullerene acceptors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We synthesized novel n-type core incorporated perylene diimide (PDI) acceptors. </LI> <LI> Panchromatic absorption was achieved via high bandgap PDI acceptors and a low bandgap donor, PTB7-Th. </LI> <LI> The n-type core effect of non-fullerene acceptors was systemically analyzed by morphological studies. </LI> <LI> The fluorinated planar core structure provided the best PCE of 4.41%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Eom, Sung-Hwan,Kang, Young-Mi,Park, Jae-Hong,Yu, Dae-Ung,Jeong, Eun-Tak,Lee, Myung-Suk,Kim, Young-Mog The Korean Society of Fisheries and Aquatic Scienc 2011 Fisheries and Aquatic Sciences Vol.14 No.3
The objective of this study was to select an effective microbial strain to improve the functional qualities of Eisenia bicyclis water extract by fermentation. For this purpose, several microorganisms isolated from traditional Korean fermented foods were inoculated and cultivated in E. bicyclis water extract. Ultimately, yeast strain YM-1 was selected for further study based on its total phenolic compound (TP) content and antioxidant activity, which were enhanced by microbial fermentation. The extract fermented by YM-1 exhibited a superior TP content and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity compared to extracts fermented by other microbes. The highest TP content and DPPH radical scavenging activity were observed after one day of YM-1 fermentation. Yeast strain YM-1 was identified as Candida utilis based on an analysis of its physiological characteristics. During fermentation of the extract by C. utilis YM-1, no significant difference was observed in the proximate composition, including moisture, crude lipid, crude protein, and crude ash. Fermentation by C. utilis YM-1 resulted in enhanced biological activity, including increases in the TP content and antioxidant activity. Thus, fermentation by C. utilis YM-1 is an attractive strategy for developing value-added food ingredients.
Eom, Sung-Hwan,Santos, Jeniel A.,Kim, Ji-Hoon,Jung, Won-Kyo,Kim, Do-Hyung,Kim, Young-Mog The Korean Society of Fisheries and Aquatic Scienc 2015 Fisheries and Aquatic Sciences Vol.18 No.3
In an effort to discover alternative phytotherapeutic antimicrobial agents to combat Streptococcus parauberis, a fish pathogenic bacterium, we evaluated the antibacterial activity of seaweed extracts in vitro. A methanolic extract of Ecklonia cava exhibited strong antibacterial activity against S. parauberis isolated from olive flounder Paralichthys olivaceus. Furthermore, the n-hexane soluble (Hexane) fraction of the E. cava methanolic extract exhibited the greatest antibacterial effect on S. parauberis strains with a minimum inhibitory concentration (MIC) ranging from 256 to $1,024{\mu}g/mL$. In addition, the MIC values of oxytetracycline against antibiotic-resistant S. parauberis were markedly reduced up to 64-fold in combination with the Hexane fraction, suggesting that the antibacterial activity of the antibiotic was restored when combined with the Hexane fraction. The interaction between both antibiotics and the Hexane fraction was assessed by the fractional inhibitory concentration (FIC) index. The Hexane fraction and oxytetracycline combination against antibiotic-resistant S. parauberis strains resulted in a median ${\sum}FIC$ range of 0.502 to 0.516. Thus, the synergistic ranges of median ${\sum}FIC$ < 1 were observed for all combinations of the Hexane fraction and oxytetracycline against S. parauberis. To the best of our knowledge, this is the first report indicating the efficacy of an E. cava extract against fish pathogenic bacterium S. parauberis.
( Sung Hwan Eom ),( Soo Jin Heo ),( Dae Sung Lee ),( Myung Suk Lee ),( Young Man Kim ),( Won Kyo Jung ),( Young Mog Kim ) 한국응용생명화학회(구 한국농화학회) 2011 Applied Biological Chemistry (Appl Biol Chem) Vol.54 No.3
Poncirus trifoliata was evaluated for antioxidant potential by several radical-scavenging assays, including 1,1-diphenyl-2-picrylhydrazyl, superoxide, hydroxyl, and alkyl radicals, using electron spin resonance technique. P. trifoliata extracts were prepared by using water and methanol, partitioning with different organic solvents. Among the tested samples, water extract and dichloromethane fraction evidenced relatively higher scavenging activities than those of other samples on reactive radicals and have high amount of antioxidant component such as flavonoids (8.5±0.3 and 8.3±0.2 mg rutin equivalents/g dry weight basis) and proanthocyanidin (2.6±0.3 and 2.8±0.5 mg catechin equivalents/g dry weight basis), respectively. Moreover, the water extract showed significantly high enhancement of cell viability against hydrogen peroxide-induced oxidative damage as well as reduction in the hydrogen peroxide-induced intracellular reactive oxygen species on CCL 13 cell line. These results indicate that P. trifoliate exerts various antioxidant effects against several reactive radicals and hydrogen peroxide-mediated cell damage. Thus, P. trifoliate could be a potential therapeutic modality for the treatment or prevention of several diseases associated with oxidative stress.
Eom, Sung-Hwan,Jung, Yeoun-Joong,Lee, Dae-Sung,Yim, Mi-Jin,Kim, Hye Seon,Lee, Sang-Hoon,Myeong, Jeong-In,Lee, Jinhwan,Kim, Hyun-Woo,Kim, Kyoung-Ho PRAGATI PRESS- INDIA 2016 Journal of environmental biology Vol.37 No.1
<P>Traditional medicinal plants contain a wide variety of chemicals that have potent antibacterial activity. To find an alternative agent of overcoming the problems of methicillin-resistant Staphylococcus aureus (MRSA), the antibacterial mechanism of Ponciruss trifoliata against MRSA was investigated. Ethyl acetate (EtOAc)-soluble extract of P. trifoliata methanolic extract was evaluated for antibacterial activity using minimum inhibitory concentration (MIC). An EtOAc sub-fraction 08 (EA08) from silica-gel open column chromatography exhibited strong anti-MRSA activity. Apart from the study to isolate single compound from EA08, a synergistic antibacterial effect between the sub-fraction and beta-lactam antibiotics against MRSA was determined. In order to elucidate the antibacterial restoring mechanism of EA08 on MRSA, mRNA expression of mecA gene and production penicillin-binding protein 2a (PBP2a) encoded by mecA gene were monitored. EA 08 showed the strongest antibacterial activity with MIC value of 256 mu g ml(-1). MIC of oxacillin against MRSA was dramatically reduced from 512 to 16 mu g ml(-1) in combination with 256 mu g ml(-1) of EA08. The fractional inhibitory concentration index of oxacillin was measured at 0.53 in combination with EA08 against MRSA, suggesting that EA08-oxacillin combinations exert synergetic effect against MRSA. The analysis of RT-PCR and Western blotting profiles revealed that EA08 inhibited mRNA expression of mecA gene and production PBP2a, which is a key determinant for beta-lactam antibiotic resistance, in a dose-dependent manner. These results indicated that EA08 eventually led to the reduction or inhibition of PBP2a production through translational inhibition in MRSA.</P>