Seongnam, South Korea
Seongnam, South Korea

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Lee S.H.,KFRI | Lee S.,KFRI | Kim J.,Hoseo University | Lee C.-K.,Korea University | And 2 more authors.
Korean Journal of Microbiology and Biotechnology | Year: 2012

Five strains out of 200 candidate strains (SG 1-9, 1-12, SG 2-8, 2-10, and 2-17) were selected to determine their antifungal activity against Raffaelea quercus-mongolicae. The 16S rDNA sequences of the five strains were determined by sequencing analysis and analyzed by the homology of the blast program at NCBI. The homology search showed that SG 1-9 and 1-12 had a 98% homology with Streptomyces cinnamoneus and 98% homology with Burkholderia cepacia, while SG 2-8, 2-10, and 2-17 had a 99% homology with Streptomyces fradiae, a 97% homology with Staphylococcus epidermidis, and a 99% homology with Staphylococcus epidermidis. Out of the five selected strains, organic extract and protein extracts of SG2-17 strain broth were employed to determine antifungal activity against Raffaelea quercus-mongolicae. The organic extract exhibited antifungal activity, but the protein extracts did not demonstrate such an activity. Three organic solvents, butanol, benzene, and ethyl acetate, were also used for determination of antifungal activities. The activity measurements revealed that benzene extract possessed the greatest inhibitory effect on the growth of Raffaelea quercus-mongolicae, with the next highest being butanol extract, and ethyl acetate extract being the lowest.


Kim J.Y.,Hoseo University | Lee J.Y.,Hoseo University | Lee W.Y.,KFRI | Yi Y.,Hoseo University | Lim Y.,Konkuk University
Korean Journal of Microbiology and Biotechnology | Year: 2010

Plants extracts are good resources to find functional compounds for human health. The following eight plants were collected and total phenolic contents were determined. Acerpsedo-siebolianum showed the highest phenolic contents, 16.4 mg/g, whereas Cercidiphyllum japonica showed the lowest contents, 1.9 mg/g. The DPPH free radical scavenging capacities of the plant extracts showed high activity in following order : Acer ginnala (21.3 μg/mL) > Cornus walteri (23.9 μg/mL) > Distylum racemosum (29.2 μg/mL) > Castanopsis cuspidata var. Thunbergii (31.7 μg/mL) > Acer psedo-siebolianum (34.6 μg/mL) > Thuijopsis dolabrata cv. Aurea (53.1 μg/mL) > Cercidiphyllum Japonica (115.2 μg/mL). Also the mushroom tyrosinase inhibitory activities of total extracts were determined at different concentration. D. racemosum extract showed highest (49.1% at 1,000 mg) in inhibitory activity than other seven extracts. The ethanol fraction (IC 50 value: 118.1 μg/mL) from D. racemosum showed more inhibitory activity than ethyl acetate fraction (IC50 value: 203 μg/mL). The ethanol fraction on showed no significant cytotoxicity in B16/F1 cells line up to 60 μg/mL. Over 80 μg/mL of ethanol fraction showed cytotoxicity in B16/F1 cells. The melanin contents of cells were significantly attenuated by ethanol fraction in a dose-dependent manner. The IC50 value of ethanol fraction was 75.4 μg/mL.


Liu P.,Washington State University | Upadhyaya P.,Xilinx Inc. | Jung J.,Washington State University | Heo D.,Washington State University | And 2 more authors.
Electronics Letters | Year: 2012

A novel LC VCO topology with switched current source is presented. Theoretical analysis is given to show the reduction of cross-paired transistors' drain current duty cycle with the implementation of current source switching, which reduces the upconversion of 1/f noise and also provides noise shaping by directly reducing 1/f noise. A 5.25-5.5 GHz LC VCO has been fabricated and measured for the proposed topology, achieving a FOM of -191 dBc/Hz, which is among the best published FOM results for 5-6 GHz VCOs in standard CMOS process. © 2012 The Institution of Engineering and Technology.


Liu P.,Washington State University | Upadhyaya P.,Xilinx Inc. | Jung J.,Washington State University | Heo D.,Washington State University | And 2 more authors.
Electronics Letters | Year: 2011

A novel load-independent switched LC VCO with PMOS dynamically switched current source and harmonic filtering is presented. The VCO has been designed and implemented with Jazz 0.18m CMOS process. At 5.47GHz carrier frequency, the VCO achieves a measured phase noise of -122.4 and -102dBc/Hz at 1MHz and 100kHz offset, respectively. The VCO works between 5.3-5.7GHz, which yields a tuning range of 400MHz. This VCO consumes 4.2mA from a 1.2V supply and the figure-of-merit (FOM) is -190.2dBc/Hz, which is among the best published FOM results for 5-6GHz VCOs in standard CMOS process. © 2011 The Institution of Engineering and Technology.


Jung J.,Washington State University | Upadyaya P.,Washington State University | Heo D.,Washington State University | Kim J.-H.,KFRI | Kim B.-S.,KFRI
Electronics Letters | Year: 2013

To minimise phase noise degradation with a wide tuning range, the proposed LC voltage controlled oscillator incorporates parallel coupled negative transconductance (gm) cells. Phase noise for wide tuning range VCOs suffers from degradation of quality factor of tank inductors or tank capacitors due to their parasitic resistance. The proposed parallel coupled negative g m cells provide additional current to compensate for the loss of phase noise. The measured results show a tuning range of 25.4% and a phase noise of - 116.7 dBc/Hz at 1 MHz offset frequency at 5.87 GHz with power consumption of 1.4 mW. The figure-of-merit with the fractional tuning range of the VCO was - 199.9 dBc/Hz, which is the best among the latest stateof- the-art wide tuning range CMOS LC VCOs. © The Institution of Engineering and Technology 2013.


Zhu S.,Washington State University | Mikul A.O.,Washington State University | Sun P.,IBM | You Y.,Washington State University | And 3 more authors.
Electronics Letters | Year: 2012

An inductor-less wideband (6-18GHz) 3-bit attenuator with low phase variations is presented based on octagonal SiGe p-type intrinsic n-type (pin) diodes. To achieve low insertion loss and high linearity, a DC bias scheme has been designed to minimise the leakage from the parasitic diodes between the P-sub and N-well of the pin diodes. The attenuator is fabricated in a standard 0.18m SiGe BiCMOS process without using post-processed transmission lines. It has a maximum attenuation range of 7dB. The minimum measured insertion loss is 7.9, 9.4, 10.6dB at 6, 12, 18GHz, respectively. Phase variation is lower than ±2.5° and the chip size, including pads, is 0.85×0.412mm 2. © 2012 The Institution of Engineering and Technology.


Zhu S.,Washington State University | You Y.,Washington State University | Heo D.,Washington State University | Kim J.-H.,KFRI | Kim B.-S.,KFRI
Electronics Letters | Year: 2011

Current-reuse and gate-modulation techniques have been presented for ultra-low power and low phase noise quadrature voltage-controlled oscillator (QVCO) design. The proposed topology overcomes the trade-off between low phase noise and low power consumption. Results demonstrate a phase noise of -123.7dBc/Hz at 1MHz offset while consuming only 680uW (including output buffers) with a 1.1V supply. © 2011 The Institution of Engineering and Technology.


Jung J.,Yonsei University | Hoe J.,Yonsei University | Yoo S.,Yonsei University | Cho K.,Yonsei University | And 2 more authors.
31st Asian Conference on Remote Sensing 2010, ACRS 2010 | Year: 2010

Forest biomass stores a large amount of terrestrial carbon and the need of periodic monitoring forest biomass has increased. kNN algorithm is one of the common method to estimate forest biomass and has been widely used for a variety of biomass mapping and applications. The objective of this study is to estimate aboveground carbon stock of Danyang area in South Korea. Field data from NFI and Landsat ETM+ satellite image were used, and carbon stock were estimated at k = 1 to 10. As a result, the lowest RMSE was found at k = 5, and the mean and the total carbon stock of Danyang area were estimated to be 28.33 ton C/ha and 2209748.91 t respectively.


Nguyen H.C.,Yonsei University | Jung J.,Yonsei University | Kim D.,Yonsei University | Heo J.,Yonsei University | Kim K.,KFRI
33rd Asian Conference on Remote Sensing 2012, ACRS 2012 | Year: 2012

To achieve quantitative information of aboveground forest biomass carbon stock by remote sensing approach, a number of methods have been conducted. This study is to examine application of regression tree (tree decision) and k-Nearest Neighbor (kNN) algorithm for forest carbon stock estimation of Chungnam province in South Korea. Dataset used for this research includes Landsat Thematic Mapper (TM) images and field data from 5th National Forest Inventory (NFI). As a result, total above forest carbon stock estimated by kNN (20,467,652.900 ton C) model is closer to the number given by Korean Institutes of Forest than regression tree's number (20,239,247.239 ton C), however RMSE from latter algorithm is less than the former, 19.168 ton C/ha and 20.063 ton C/ha, respectively.

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