Kyung Tae Kim

Chung-Ang University, Sŏul, Seoul, South Korea

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Publications (130)240.67 Total impact

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    ABSTRACT: Despite intensive research on photochemical activation of sol–gel metal oxide materials, the relatively long processing time and lack of deep understanding of the underlying chemical courses have limited their broader impact on diverse materials and applications such as thin-film electronics, photovoltaics, and catalysts. Here, in-depth studies on the rapid photochemical activation of diverse sol–gel oxide films using various spectroscopic and electrical investigations for the underlying physicochemical mechanism are reported. Based on the exhaustive chemical and physical analysis, it is noted that deep ultraviolet-promoted rapid film formation such as densification, polycondensation, and impurity decomposition is possible within 5 min via in situ radical-mediated reactions. Finally, the rapid fabrication of all-solution metal oxide thin-film-transistor circuitry, which exhibits stable and reliable electrical performance with a mobility of >12 cm2 V−1 s−1 and an oscillation frequency of >650 kHz in 7-stage ring oscillator even after bending at a radius of <1 mm is demonstrated.
    Advanced Functional Materials 03/2015; 25(19). DOI:10.1002/adfm.201500545 · 10.44 Impact Factor
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    ABSTRACT: Incorporation of Zr into AlOx matrix generates an intrinsically activated ZAO surface enabling formation of a stable semiconducting IGZO film and good interfacial property. Photochemically annealed metal-oxide devices and circuits with the optimized sol-gel ZAO dielectric and IGZO semiconductor layers demonstrate the high performance and electrically/mechanically stable operation of flexible electronics fabricate via low-temperature solution process. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Advanced Materials 01/2015; 27(7). DOI:10.1002/adma.201404296 · 15.41 Impact Factor
  • Kyung Tae Kim, Yeong Seong Eom, Injoon Son
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    ABSTRACT: Carbon nanotube/bismuth-selenium-tellurium composites were fabricated by consolidating CNT/Bi2(Se,Te)3 composite powders prepared from a polyol-reduction process. The synthesized composite powders exhibit CNTs homogeneously dispersed among Bi2(Se,Te)3 matrix nanopowders of 300 nm in size. The powders were densified into a CNT/Bi2(Se,Te)3 composite in which CNTs were randomly dispersed in the matrix through spark plasma sintering process. The effect of an addition of Se on the dimensionless figure-of-merit (ZT) of the composite was clearly shown in 3 vol.% CNT/Bi2(Se,Te)3 composite as compared to CNT/Bi2Te3 composite throughout the temperature range of 298 to 473 K. These results imply that matrix modifications such as an addition of Se as well as the incorporation of CNTs into bismuth telluride thermoelectric materials is a promising means of achieving synergistic enhancement of the thermoelectric performance levels of these materials.
    Journal of Nanomaterials 01/2015; 2015:1-6. DOI:10.1155/2015/202415 · 1.61 Impact Factor
  • 12/2014; 10(4):177-182. DOI:10.11629/jpaar.2014.10.4.177
  • 12/2014; 21(6):460-466. DOI:10.4150/KPMI.2014.21.6.460
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    ABSTRACT: The fabrication and evaluation of a wide-range vacuum gauge for monitoring the pressure level inside an infrared focal plane array and a wafer-level packaging (WLP) are reported. The proposed vacuum gauge has a microbolometer structure produced using the conventional surface micromachining process to achieve thermal isolation and high sensitivity. This structure has other advantages such as fast response time, a wider measurement range and easier integration to a Si substrate compared with other pressure sensors. The evaluation results show that the fabricated vacuum gauge has a linear dynamic range and a sensitivity of 10(-3) to 10(5) K/W/torr for vacuum pressures ranging from 10(-6) to 760 torr. Also, the response time to vacuum change is reduced from 0.11 s at 10(-5) torr to 15 ms at 100 torr. Therefore, the microbolometer-based vacuum gauge has good potential for application in WLP, and it is possible to hermetically seal it with various read-out integrated circuit substrates.
    Micro & Nano Letters 12/2014; 9(12):835-840. DOI:10.1049/mnl.2014.0378 · 0.80 Impact Factor
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    ABSTRACT: Capillary electrochromatography was employed for enantioseparation of α-amino acids and their derivatives. (-)-18-Crown-6-2,3,11,12-tetracarboxylic acid bonded on the silica was used as the chiral stationary phase and methanol/Tris-citric acid (20 mM, pH 3.0-4.5) (20:80, v/v) was used as mobile phase. The enantioseparation performance was discussed and structure-chiral separation relationship were tried to be explained. The enantiomeric resolution was increased when the pH of the mobile phase decreased or hydrogen of amino acid was substituted with halogen. The resolution of 4-bromophenylalanine was 2.37 at pH 4.5, however, this value was increased to 3.35 at pH 3.0. Bromo- or chloro-substituted phenylalanine tended to show higher resolution than fluoro-substituted one. For fluoro-substituted phenylalanine the resolution was increased in order of 4-, 3- and 2-substituted one. α-Methyltryptamine did not show reasonable separation. As the thermodynamic study is a useful tool to understand the chiral recognition, the temperature effect on the enantioseparation was studied and the thermodynamic parameters were calculated. The most important mechanism of chiral recognition for the analytes tested could be barrier effects based on the thermodynamic calculations. The coefficient of determination between hydrophobicity and separation factor was found to be 0.87, indicating favorable separation with higher hydrophobicity of amino acids.
    Archives of Pharmacal Research 11/2014; DOI:10.1007/s12272-014-0507-1 · 1.75 Impact Factor
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    ABSTRACT: Reduced graphene oxide/alumina composite powders were prepared by mixing of graphene oxides and aluminum ions at the molecular-level. It was found that the composite consolidated from the powders showed that reduced graphene oxide were homogeneously dispersed and strongly bonded with the alumina matrix by oxygen atoms presenting at reduced graphene oxide/alumina interfaces. Both the hardness and the toughness of the composites were enhanced simultaneously by the addition of reduced graphene oxide, which act as bridges to restrain the propagation of cracks in the alumina matrix. It is clarified that graphenes can be utilized as promising reinforcements for enhancement in mechanical properties of ceramic materials when the molecular-level mixing process is applied.
    Carbon 11/2014; 78:212–219. DOI:10.1016/j.carbon.2014.06.074 · 6.16 Impact Factor
  • 10/2014; 47(5):215-220. DOI:10.5695/JKISE.2014.47.5.215
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    ABSTRACT: RNA interference (RNAi), mediated by small non-coding RNAs (e.g., miRNAs, siRNAs), influences diverse cellular functions. Highly complementary miRNA-target RNA (or siRNA-target RNA) duplexes are recognized by an Argonaute family protein (Ago2), and recent observations indicate that the concentration of Mg2+ ions influences miRNA targeting of specific mRNAs, thereby modulating miRNA-mRNA networks. In the present report, we studied the thermodynamic effects of differential [Mg2+] on slicing (RNA silencing cycle) through molecular dynamics simulation analysis, and its subsequent statistical analysis. Those analyses revealed different structural conformations of the RNA duplex in Ago2, depending on Mg2+ concentration. We also demonstrate that cation effects on Ago2 structural flexibility are critical to its catalytic/functional activity, with low [Mg2+] favoring greater Ago2 flexibility (e.g., greater entropy) and less miRNA/mRNA duplex stability, thus favoring slicing. The latter finding was supported by a negative correlation between expression of an Mg2+ influx channel, TRPM7, and one miRNA's (miR-378) ability to downregulate its mRNA target, TMEM245. These results imply that thermodynamics could be applied to siRNA-based therapeutic strategies, using highly complementary binding targets, because Ago2 is also involved in RNAi slicing by exogenous siRNAs. However, the efficacy of a siRNA-based approach will differ, to some extent, based on the Mg2+ concentration even within the same disease type; therefore, different siRNA-based approaches might be considered for patient-to-patient needs.
    PLoS ONE 10/2014; 9(10). DOI:10.1371/journal.pone.0109745 · 3.53 Impact Factor
  • Cancer Research 10/2014; 74(19 Supplement):523-523. DOI:10.1158/1538-7445.AM2014-523 · 9.28 Impact Factor
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    ABSTRACT: Amorphous indium gallium zinc oxide(IGZO) based thin film transistors(TFTs) have been widely studied due to their good electrical properties such as optical transparent and field effect mobility. The demand for low-cost process of thin film devices has needed solution processed metal oxide TFTs. Although many effective ways of fabricating soluble metal oxide TFTs have been investigated1, there is still the necessity of increasing field effect mobility of TFTs. As a one way of mobility improvement, low work function metals(Ca, Ti) were used as passivation in terms of capping layer on top of the IGZO active layer2,3. The metal capping method has obvious several advantages, but we expect the additional process cost due to a step of patterning the capping layer. Also, because nature of metals has no transparent characteristics, this pure metal capping method could not available in transparent applications. In this paper, we suggest a real time deposition method of electrodes and capping layer for solution processed IGZO TFTs with maintaining transparency and process cost.
    2014 72nd Annual Device Research Conference (DRC); 06/2014
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    ABSTRACT: Marine-derived natural products from invertebrates comprise an extremely diverse and promising source of the compounds from a wide variety of structural classes. This study describes the discovery of five marine natural products with activity against Trypanosoma species by natural product library screening using whole cell in vitro assays. We investigated the anti-trypanosomal activity of the extracts from the soft corals and echinoderms living in Vietnamese seas. Of the samples screened, the methanolic extracts of several marine organisms exhibited potent activities against cultures of Trypanosoma brucei and T. cruzi (EC50 < 5.0 μg/mL). Among the compounds isolated from these extracts, laevigatol B (1) from Lobophytum crassum and L. laevigatum, (24S)-ergost-4-ene-3-one (2) from Sinularia dissecta, astropectenol A (3) from Astropecten polyacanthus, and cholest-8-ene-3β,5α,6β,7α-tetraol (4) from Diadema savignyi showed inhibitory activity against T. brucei with EC50 values ranging from 1.57 ± 0.14 to 14.6 ± 1.36 μM, relative to the positive control, pentamidine (EC50 = 0.015 ± 0.003 μM). Laevigatol B (1) and 5α-cholest-8(14)-ene-3β,7α-diol (5) exhibited also significant inhibitory effects on T. cruzi. The cytotoxic activity of the pure compounds on mammalian cells was also assessed and found to be insignificant in all cases. This is the first report on the inhibitory effects of marine organisms collected in Vietnamese seas against Trypanosoma species responsible for neglected tropical diseases.
    Molecules 06/2014; 19(6):7869-80. DOI:10.3390/molecules19067869 · 2.42 Impact Factor
  • Joon Hyuk Choi, Kyung Tae Kim, Sang Moo Kim
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    ABSTRACT: Enzymatic hydrolysis of squid meat was optimized and the biochemical properties of solubility, amino acid composition, and contents of nucleic acid related compounds were determined. Optimal hydrolysis conditions were a pH of 7.0, a hydrolysis time of 5.9 h, a temperature of 55°C, and an enzyme/substrate ratio of 2.4%. More than 75% of squid meat hydrolysate was soluble in a wide pH range. The sweet and savory tasting amino acid contents of the squid hydrolysate were higher than the contents of bitter tasting amino acids. The hydrophilic amino acid content of squid meat was lower than the content of hydrophobic amino acids. The inosine monophosphate content of squid hydrolysate was highest among nucleic acid related compounds. Based on a sensory evaluation, squid complex seasoning was similar or superior to commercial complex seasonings. A squid hydrolysate can be used as an ingredient for manufacture of food products.
    Food science and biotechnology 04/2014; 23(2):417-423. DOI:10.1007/s10068-014-0057-9 · 0.66 Impact Factor
  • ChemInform 03/2014; 45(10):no-no. DOI:10.1002/chin.201410229
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    ABSTRACT: Piwi-interacting RNAs (piRNAs) are 26-31 nt small noncoding RNAs that are processed from their longer precursor transcripts by Piwi proteins. Localization of Piwi and piRNA has been reported mostly in nucleus and cytoplasm of higher eukaryotes germ-line cells, where it is believed that known piRNA sequences are located in repeat regions of nuclear genome in germ-line cells. However, localization of PIWI and piRNA in mammalian somatic cell mitochondria yet remains largely unknown. We identified 29 piRNA sequence alignments from various regions of the human mitochondrial genome. Twelve out 29 piRNA sequences matched stem-loop fragment sequences of 7 distinct tRNAs. We observed their actual expression in mitochondria subcellular fractions by inspecting mitochondrial-specific small RNA-Seq datasets. Of interest, the majority of the 29 piRNAs overlapped with multiple longer transcripts (expressed sequence tags) that are unique to the human mitochondrial genome. The presence of mature piRNAs in mitochondria was detected by qRT-PCR of mitochondrial subcellular RNAs. Further validation showed detection of Piwi by colocalization using anti-Piwil1 and mitochondria organelle-specific protein antibodies.
    Biochemical and Biophysical Research Communications 03/2014; 446(1). DOI:10.1016/j.bbrc.2014.02.112 · 2.28 Impact Factor
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    ABSTRACT: Marine-derived natural products from invertebrates comprise an extremely diverse and promising source of the compounds from a wide variety of structural classes. This study describes the discovery of five marine natural products with activity against Trypanosoma species by natural product library screening using whole cell in vitro assays. We investigated the anti-trypanosomal activity of the extracts from the soft corals and echinoderms living in Vietnamese seas. Of the samples screened, the methanolic extracts of 7870 several marine organisms exhibited potent activities against cultures of Trypanosoma brucei and T. cruzi (EC 50 < 5.0 μg/mL). Among the compounds isolated from these extracts, laevigatol B (1) from Lobophytum crassum and L. laevigatum, (24S)-ergost-4-ene-3-one (2) from Sinularia dissecta, astropectenol A (3) from Astropecten polyacanthus, and cholest-8-ene-3β,5α,6β,7α-tetraol (4) from Diadema savignyi showed inhibitory activity against T. brucei with EC 50 values ranging from 1.57 ± 0.14 to 14.6 ± 1.36 μM, relative to the positive control, pentamidine (EC 50 = 0.015 ± 0.003 μM). Laevigatol B (1) and 5α-cholest-8(14)-ene-3β,7α-diol (5) exhibited also significant inhibitory effects on T. cruzi. The cytotoxic activity of the pure compounds on mammalian cells was also assessed and found to be insignificant in all cases. This is the first report on the inhibitory effects of marine organisms collected in Vietnamese seas against Trypanosoma species responsible for neglected tropical diseases.
  • Kyung Tae Kim, Hee Yong Youn
    International Journal of Distributed Sensor Networks 01/2014; 2014:1-12. DOI:10.1155/2014/828675 · 0.92 Impact Factor
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    ABSTRACT: With IPTV, channel zapping time is one of the significant problems. It occurs when the user wants to change the channel but needs to wait until the target channel is available. Various schemes reducing the time have been suggested, which download the candidate channels of the future use in advance. In this paper we propose a new method which further reduces the channel zapping time by pre-downloading the candidate channels during the time latency between two successive push operations of the buttons of remote controller made by the user. Computer simulation verifies its effectiveness in various operational conditions. More importantly, it can be employed together with other scheme of reducing channel zapping time without any additional overhead.
    2014 IEEE 11th Consumer Communications and Networking Conference (CCNC); 01/2014

Publication Stats

850 Citations
240.67 Total Impact Points

Institutions

  • 2012–2015
    • Chung-Ang University
      • School of Electrical and Electronics Engineering
      Sŏul, Seoul, South Korea
  • 2013–2014
    • Korea Advanced Nano Fab Center
      화성시, Gyeonggi-do, South Korea
    • Pusan National University
      Tsau-liang-hai, Busan, South Korea
    • Inje University Paik Hospital
      Sŏul, Seoul, South Korea
    • National Institute of Environmental Research
      Sŏul, Seoul, South Korea
  • 2012–2014
    • Chungnam National University
      • College of Pharmacy
      Daiden, Daejeon, South Korea
  • 2010–2014
    • Korea Institute of Materials Science
      Sŏngnam, Gyeonggi Province, South Korea
  • 2007–2014
    • National Cancer Center Korea
      • • Molecular Epidemiology Branch
      • • Division of Cancer Biology
      Kōyō, Gyeonggi Province, South Korea
  • 2005–2014
    • Sungkyunkwan University
      • College of Information and Communication Engineering (SoICE)
      Sŏul, Seoul, South Korea
  • 1998–2013
    • Seoul National University
      • • Department of Materials Science and Engineering
      • • Department of Food and Nutrition
      Sŏul, Seoul, South Korea
  • 2011
    • Yeungnam University
      Daikyū, Daegu, South Korea
  • 2006–2011
    • Korea Advanced Institute of Science and Technology
      • Department of Materials Science and Engineering
      Sŏul, Seoul, South Korea
  • 2008–2010
    • Konkuk University
      Sŏul, Seoul, South Korea
    • Hanyang University
      • Major in Obstetrics and Gynecology
      Sŏul, Seoul, South Korea
  • 2009
    • Chonnam National University
      • Division of Applied Bioscience and Biotechnology
      Gwangju, Gwangju, South Korea
    • Catholic Kwandong University
      Gangneung, Gangwon-do, South Korea
    • Cheil General Hospital
      Sŏul, Seoul, South Korea
  • 2006–2007
    • Myongji University
      • Department of Mathematics
      Seoul, Seoul, South Korea
  • 2004–2007
    • Gachon University
      • Department of Electrical Engineering
      Sŏngnam, Gyeonggi Province, South Korea
  • 2003–2006
    • Seoul National University Hospital
      Sŏul, Seoul, South Korea
  • 2001
    • Pohang University of Science and Technology
      • Department of Electrical and Computer Engineering
      Geijitsu, North Gyeongsang, South Korea
    • Yonsei University
      • Department of Electrical and Electronic Engineering
      Seoul, Seoul, South Korea