• Bulletin of the Korean Chemical Society
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• v.19 no.3
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• pp.328-332
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• 1998

Anionic ring-opening polymerization of 3,4-[(dimethylsilyl)isopropyl]benzo-1,1-dimethyl-1-silacyclopentene in the presence of n-butyllithium and HMPA in THF at - 78 ℃ afforded poly[3,4-(dimethylsilylisopropyl)benzo-1,1-dimethyl-1-silapentene]. The characteristic Si-H stretching frequency in the IR is observed at 2100 cm-1. The polycarbosilane has been modified by chloroplatinic acid catalyzed addition of styrene to the polycarbosilane SiH units. Molecular weights and thermal properties of the polymers were compared. The sol-gel polymerization of 3,4-[(dimethoxysilyl)isopropyl]benzo-1,1-dimethoxy-1-silacyclopentene in the presence of aqueous HCl or NaOH in THF resulted in a cross-linked polysiloxane. The xerogel has a low surface area of 13-14 m2/g and is stable up to about 400 ℃ with only 5% weight loss under a nitrogen atmosphere.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.329-332
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• 2001

The stability of red pigment isolated from RF101 was determined over a period of storage for the pH, light, temperature and various metal ions. The absorption maximum of red pigment was 510nm. Red pigment was stable from pH 5 to pH 9 and in dark conditions. It was also stable against temperature below $25^{\circ}C$ and in $K^+$, $Ca^{2+}$, $Mg^{2+}$, Antibacterial activity of RF101 showed growth-inhibitory activity against plant pathogens Agrobacterium spp.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.331-332
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• 2006

Transport systems which are the important part of the factory automation have much influence on improving productivity. Object transport systems are driven typically by the magnetic field and conveyer belt. In recent years, as the transmission and processing of information is required more quickly, demands of optical elements and semiconductors increase. However, conventional transport systems are not adequate for transportation of those. The reason is that conveyor belts can damage precision optical elements by the contact force and magnetic systems can destroy the inner structure of semiconductor by the magnetic field. In this paper, the levitation transport system using ultrasonic wave is developed for transporting precision elements without damages. Vibration modes of each flexural beam are verified by using Laser Scanning Vibrometer.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.4
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• pp.325-332
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• 2016

Resveratrol, a phytoalexin, is reported to activate AMP-activated protein kinase (AMPK) in vascular cells. The blood-brain barrier (BBB), formed by specialized brain endothelial cells that are interconnected by tight junctions, strictly regulates paracellular permeability to maintain an optimal extracellular environment for brain homeostasis. The aim of this study was to elucidate the effects of resveratrol and the role of AMPK in BBB dysfunction induced by lipopolysaccharide (LPS). Exposure of human brain microvascular endothelial cells (HBMECs) to LPS ($1{\mu}g/ml$) for 4 to 24 hours week dramatically increased the permeability of the BBB in parallel with lowered expression levels of occluding and claudin-5, which are essential to maintain tight junctions in HBMECs. In addition, LPS significantly increased the reactive oxygen species (ROS) productions. All effects induced by LPS in HBVMCs were reversed by adenoviral overexpression of superoxide dismutase, inhibition of NAD(P) H oxidase by apocynin or gain-function of AMPK by adenoviral overexpression of constitutively active mutant (AMPK-CA) or by resveratrol. Finally, upregulation of AMPK by either AMPK-CA or resveratrol abolished the levels of LPS-enhanced NAD(P)H oxidase subunits protein expressions. We conclude that AMPK activation by resveratrol improves the integrity of the BBB disrupted by LPS through suppressing the induction of NAD(P)H oxidase-derived ROS in HBMECs.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.553-559
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• 1998

cDNA of human thrombopoietin (hTPO) amplified by polymerase chain reaction from a cDNA library of human fetal liver was cloned. EPO-like domains ($hTPO_{153} \;or\; hTPO_{l63})\; of\; hTPO(hTPO_{332}$) were expressed in Escherichin coli using several kinds of expression systems, such as ompA secretion, thioredoxin fusion, and the $P_L$ and T7 expression systems. To obtain $hTPO_{153}$ in soluble form, $hTPO_{153}$ cDNA was fused in-frame behind the gene encoding ompA signal sequence and thioredoxin protein. When fused with either of the genes, $hTPO_{153}$ was not expressed to the detectable level. However, a high level expression of the EPO-like domain of hTPO was obtained using the PL and T7 expression system. $hTPO_{153} \;or\; hTPO_{l63} cDNA were subcloned into the pLex and pET-28a(＋) vectors under the control of the inducible$ P_L\;T_7$ promoter, respectively. Proteins expressed using pl.ex vector and pET-28a(＋) detected in insoluble forms with an expression level of about 14% and 9% of total cellular proteins, respectively, and the level of expression was rapidly diminished in 2 h after the maximum level of expression was reached.

• Journal of Life Science
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• v.25 no.3
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• pp.257-262
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• 2015

The genetic variability of four species of the genus Zoysia collected from South Korea was analyzed using an inter-simple sequence repeat (ISSR) marker system. Polymerase chain reactions (PCR) with eight ISSR primers generated 86 amplicons, 76 (87.1%) of which were polymorphisms. The polymorphism information content (PIC) value of the ISSR marker system was 0.848. The percentage of polymorphic loci (P_p) ranged from 41.2% to 44.7%. Nei’s gene diversity (H) ranged from 0.149 to 0.186, with an average overall value of 0.170. The mean of Shannon’s information index (I) value was 0.250. Total genetic diversity values (H_T) varied between 0.356 (ISSR-1) and 0.418 (ISSR-16), for an average overall polymorphic loci of 0.345. Interlocus variation in within-species genetic diversity (H_S) was low (0.170). On a per-locus basis, the proportion of total genetic variation due to differences among species (G_ST) was 0.601. This indicated that about 60.1% of the total variation was among species. Thus, about 39.9 of genetic variation was within species. The estimate of gene flow, based on G_ST, was very low among species of the genus Zoysia (N_m = 0.332). The phylogenic tree showed three distinct groups: Z. macrostachya and Z. tenuifolia clades and other species were formed the separated clusters. In conclusion, the ISSR assay was useful for detecting genetic variation in the genus Zoysia, and its discriminatory power was comparable to that of other genotyping tools.

• Clean Technology
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• v.24 no.4
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• pp.332-338
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• 2018

Currently graphite is used as an anode active material for lithium ion battery. However, since the maximum theoretical capacity of graphite is limited to $372mA\;h\;g^{-1}$, a new anode active material is required for the development of next generation high capacity and high energy density lithium ion battery. The maximum theoretical capacity of Si is $4200mA\;h\;g^{-1}$, which is about 10 times higher than the maximum theoretical capacity of graphite. However, since the volume expansion rate is almost 400%, the irreversible capacity increases as the cycle progresses and the discharge capacity relative to the charge is remarkably reduced. In order to solve these problems, it is possible to control the particle size of the Si anode active material to reduce the mechanical stress and the volume change of the reaction phase, thereby improving the cycle characteristics. Therefore, in order to minimize the decrease of the charge / discharge capacity according to the volume expansion rate of the Si particles, the improvement of the cycle characteristics was carried out by pulverizing Si by a dry method with excellent processing time and cost. In this paper, Si is controlled to nano size using vibrating mill and the physicochemical and electrochemical characteristics of the material are measured according to experimental variables.

• Wind and Structures
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• v.12 no.4
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• pp.313-332
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• 2009

This paper numerically and experimentally investigates the control performance of the active mass damper (AMD) systems in a 26-story high-rise building in use. This is the first full-scale application of the AMD system for suppressing the wind-induced vibration of a building structure in Korea. In addition, the AMD system was installed on top of the building already in use, which may be the world's first implementation case. In order to simultaneously mitigate the transverse-torsional coupled vibration of the building, two AMD systems were applied. Moreover, the H-infinity control algorithm has been developed to utilize the maximum capacity of the AMD system. From the results of numerical simulation using the wind load obtained from the wind tunnel tests, it was found that the maximum acceleration responses of the building were reduced significantly. Moreover, the control performance of the installed AMD system was examined by carrying out the free and forced vibration tests. The acceleration responses on top of the building in the controlled case measured under strong wind loads were compared with those in the uncontrolled case numerically simulated by using the wind load deduced from the measured data and a structural model of the building. It is demonstrated that the AMD system shows good control performance in reducing the building accelerations.

• BMB Reports
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• v.31 no.4
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• pp.328-332
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• 1998

The 8-hydroxyisocoumarin, named Centipedin, which has a significant antibiotic activity, was separated and solubilized with organic solvents, such as diethyl ether from centipede Scolopendra subspinipes multilans L. Koch. The Centipedin was purified by silicic acid column and high S cation exchange chromatography followed by reverse-phase HPLC. It was confirmed that Centipedin has a potent antibiotic effectiveness against Gram-negative Klebsiella pneumoniae ATCC 8308. The results showed that Centipedin blocks both DNA replication and RNA transcription during the growth of this pathogen in vivo. The biosynthesis of antibiotic 8-hydroxyisocoumarin was studied in vivo by feeding $[^{14}C]-labelled$ compound as a precursor to live centipede, in which $[^{14}C]acetate$ was the most efficiently incorporated into the Centipedin within 30 h after injection. Also, in vitro study on the biosynthesis of Centipedin showed that efficient incorporation of $[^{14}C]acetate$ occurred at pH range 5.0-7.0 for 10 h incubation and decreased significantly after then. It is suggested that 8-hydroxyisocoumarin is one of the defense compounds acting on bacterial infection in Scolopendra subspinipes.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.1
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• pp.90-96
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• 2008

We compared the effects of supplementing $L-lysine{\cdot}SO_4$ to L-lysine HCl on growth performance, nutrient digestibility and nitrogen retention in weaning pigs. A total of 96 crossbred pigs, weaned at $21{\pm}3$ days of age and with an average initial body weight (BW) $6.23{\pm}0.01kg$, were given one of 4 treatments, which translated into 6 replicates of 4 pigs in each pen. The animals were randomly assigned to four dietary treatments according to a randomized completely block design (RCBD) as follows: 1) control-no synthetic lysine, lysine deficient (0.80% total lysine); 2) L-C (= 0.2% L-lysine HCl); 3) K-L-S (= 0.332% $L-lysine{\cdot}SO_4$, A company); 4) C-L-S (= 0.332% $L-lysine{\cdot}SO_4$, B company). Diets were formulated with corn, soy bean meal, and corn gluten meal as the major ingredients, and all nutrients except the lysine met or exceeded NRC requirements (1998). The lysine content of supplemented synthetic lysine was the same in all treatment groups except the control. No clinical health problems associated with the dietary treatments were observed. During the entire experimental period, body weight, average daily gain (ADG) and feed efficiency (G:F ratio) increased (p<0.01) in pigs fed the experimental diets supplemented with L-lysine??HCl or $L-lysine{\cdot}SO_4$ produced by A company, irrespective of the two synthetic lysine sources. Although the supplementation of $L-lysine{\cdot}SO_4$ produced by B company tended to improve the ADG and G:F ratio, significant differences were not seen among all treatments and tended to be lower than the L-C (L-lysine HCl) and K-L-S ($L-lysine{\cdot}SO_4$ groups using the product from A company). The digestibility of crude protein (CP) was increased by the supplementation of synthetic lysine (p<0.05), irrespective of the L-lysine source (L-C, K-L-S, C-L-S). The results of this study showed that ADG, G:F ratio, and CP digestibility improved when $L-lysine{\cdot}SO_4$ or L-lysine HCl was supplemented into the weaning pigs' diet. There was a clear difference in efficacy between the two $lysine{\cdot}SO_4$ products based upon the growth performance of weaning pigs. Consequently, the bioavailability of $lysine{\cdot}SO_4$ products should be evaluated before supplementation of synthetic lysine in swine diets.