• The Korean Journal of Pharmacology
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• v.22 no.2
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• pp.96-104
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• 1986

Higenamine, dl-1-( 4-hydroxybenzyl)-6, 7-dihydroxy-1 ,2, 3 ,4-tetrahydroisoquinoline has been synthesized and evaluated for hemodynamic actions using rabbits under pentobarbital anesthesia. Concentration-related fall of mean blood pressure was observed, where diastolic blood presure was significantly lowered at 10 ug/kg/min or above (p<.05), while the systolic blood pressure was slightly increased or unaffected, thereby, causing increment of pulse pressure. No significant change was occured in heart rate, however, carotid artery blood flow was significantly (p<.05) increased. These actions were inhibited with pretreatment of 0.3 mg/kg of propranolol, beta-adrenoceptor antagonist, 5 minutes before infusion of higenamine indicating that higenamine compete with propranolol for the so-called beta adrenergic receptor. As comparison, the same procedure was applied to isoproterenol as well, where typical antagonism of propranolol against isoproterenol was shown. From these findings the vasodilating and diastolic blood pressure lowing effects could be explained in terms of cardiac beta stimulating action, however, dopamine receptor activation could not be excluded because no significant changes observed in chronotropism.

• Korean Journal of Food Science and Technology
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• v.48 no.1
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• pp.59-65
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• 2016

This study was carried out to investigate the total polyphenols, antioxidant activities, and melanin synthesis inhibition of several pear cultivars (Pyruspyrifolia). The total polypenolic content of five pear cultivars was high in the unripe developmental stage. Total polyphenolic content of the Chuwhangbae cultivar extract was higher than that of other pear cultivars regardless of the developmental stage. However, the total flavonoid content did not differ between cultivars or developmental stages. The phenolic compound, arbutin has an inhibitory effect on melanogenesis. Arbutin levels in pear cultivars declined as the fruit matured. The free radical scavenging activity of the extract also decreased as the fruit ripened. In B16F10 mouse melanoma cells, most of the cultivar extracts inhibited melanin synthesis by about 50% at a $100{\mu}g{\cdot}mL^{-1}$ concentration, except in the Gamcheonbae extract until 90 days after full bloom. We have confirmed that the extract of pear cultivars have antioxidant activity and skin-whitening effects.

• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.328-333
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• 2014

Folate is a water-soluble vitamin B that is required for the synthesis of amino acids and nucleic acids. It plays an important role in cell division and cell growth in several living organisms. The purpose of this study was to screen strong folate-synthesizing bacteria and to optimize their culture conditions for folate production. Folate production was quantified by microbiological assays by using folate-dependent strain Lactobacillus rhamnosus KCTC 3237. Folate derivatives were identified by LC-MS/MS. Of the 65 strains of bifidobacteria and lactobacilli tested, L. plantarum Fol 708 demonstrated the greatest ability to produce folate. Its optimal pH for folate production was 5.5 in a pH-controlled, lab-scale fermenter. Coculturing L. plantarum Fol 708 with L. brevis GABA 100 in a milk medium enhanced the level of folate produced in comparison to culturing L. plantarum Fol 708 alone.

• Tuberculosis and Respiratory Diseases
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• v.58 no.1
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• pp.31-42
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• 2005

Background : Peroxiredoxins (Prxs) are a relatively newly recognized, novel family of peroxidases that reduce $H_2O_2$ and alkylhydroperoxide into water and alcohol, respectively. There are 6 known isoforms of Prxs present in human cells. Normally, Prxs exist in a head-to-tail homodimeric state in a reduced form. However, in the presence of excess $H_2O_2$, it can be oxidized on its catalytically active cysteine site into inactive oxidized forms. This study surveyed the types of the Prx isoforms present in the pulmonary epithelial, macrophage, endothelial, and other cell lines and observed their response to oxidative stress. Methods : This study examined the effect of exogenous, excess $H_2O_2$ on the Prxs of established cell lines originating from the pulmonary epithelium, macrophages, and other cell lines, which are known to be exposed to high oxygen partial pressures or are believed to be subject to frequent oxidative stress, using non-reducing SDS polyacrylamide electrophoresis (PAGE) and 2 dimensional electrophoresis. Result : The addition of excess $H_2O_2$ to the culture media of the various cell-lines caused the immediate inactivation of Prxs, as evidenced by their inability to form dimers by a disulfide cross linkage. This was detected as a subsequent shift to its monomeric forms on the non-reducing SDS PAGE. These findings were further confirmed by 2 dimensional electrophoresis and immunoblot analysis by a shift toward a more acidic isoelectric point (pI). However, the subsequent reappearance of the dimeric Prxs with a comparable, corresponding decrease in the monomeric bands was noted on the non-reducing SDS PAGE as early as 30 minutes after the $H_2O_2$ treatment suggesting regeneration after oxidation. The regenerated dimers can again be converted to the inactivated form by a repeated $H_2O_2$ treatment, indicating that the protein is still catalytically active. The recovery of Prxs to the original dimeric state was not inhibited by a pre-treatment with cycloheximide, nor by a pretreatment with inhibitors of protein synthesis, which suggests that the reappearance of dimers occurs via a regeneration process rather than via the de novo synthesis of the active protein. Conclusion : The cells, in general, appeared to be equipped with an established system for regenerating inactivated Prxs, and this system may function as a molecular "on-off switch" in various oxidative signal transduction processes. The same mechanisms might applicable other proteins associated with signal transduction where the active catalytic site cysteines exist.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.77-87
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• 2010

Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) has been an increasing problem worldwide since the initial reports over 40 years ago. To examine new drug leads with potential antibacterial activities, Various N'-[(-3-substituted-4-oxo-1,3-thiazolidin-2-ylidene]-4-hydroxy benzohydrazide (4a-4.i) and N'-[-(3,4-disubstituted)-1,3-thiazolidin-2ylidene)]-4-hydroxybenzohydrazide from (5.a-5.i) to (10.a-10.i) were synthesized using appropriate synthetic route. The entire test compounds (4.a-4.i) and from (5.a-5.i) to (10.a-10.i) were assayed in vitro against s. aureus strain. The minimum inhibitory concentration (MIC) was determined for test compounds and for reference standards. The test compounds showed significant antibacterial activity against the strains used, when tested in vitro. In general, p-hydroxybenzohydrazide ring and substituted thiazoline ring are essential for antimicrobial activity. Among the compounds tested, compounds 6.f, 7.g, 9.f and 10.f, 10 i were found to be most potent. The test compounds were found nontoxic upto the dose level of 2000 ${\mu}g$/mL. The intact compounds were then subjected for 3D-QSAR studies. 3D-QSAR study based on the principal of alignment of pharmacophoric features by Schrodinger PHASE module. The 3D-QSAR study allowed us to confirm the preferential binding mode of p-hydroxybenzohydrazide inside the active site.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.251-258
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• 2015

In the study, PLLA with 12,000 g/mol ($M_n$) and 14,000 g/mol ($M_w$) was synthesized from L-lactide, and used to synthesize PLLA-Br intermediate. PLLA-block-PMMA with 84,000 g/mol ($M_n$) and 126,000 g/mol ($M_w$) was finally synthesized from PLLA-Br intermediate. The glass transition temperature ($T_g$) and initial pyrolysis temperature of PLLA-block-PMMA are $95.5^{\circ}C$ and $289^{\circ}C$, respectively. The PLA film of $50{\pm}3{\mu}m$ thickness was prepared by blending PLA with 9 phr PLLA-block-PMMA followed by stretching biaxially at 3 times under $95^{\circ}C$, and annealing at $120^{\circ}C$ for 2 min. The light transmittance at 550 nm and tensile strength of the film are 88.5% and 44.5 MPa, respectively. To enhance the tensile strength of PLA film, it was required to keep the film more than 2 min at $120^{\circ}C$ during the annealing step after a biaxially orientation.

• Polymer(Korea)
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• v.39 no.3
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• pp.487-492
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• 2015

The effects of chemical structure of alkyl groups of norbornene carboxylic alkyl esters(methyl, octyl, 4-chlorobenzyl) and endo/exo ratios of norbornene monomers on activity of palladium catalyst and polymerization behavior were investigated. Norbornene ester monomers were synthesized from the reaction of 5-norborene-2-carboxylic acid and various alcohols. Polymerization catalyst, di-${\mu}$-chloro-bis(-methoxybicyclo[2,2,1]-hept-2-ene)palladium(II) (DCBMP), was synthesized according to the literature procedure and silver hexafluoroantimonate ($AgSbF_6$) was used as a conjugate anion source. Gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) were the principal techniques for polymer characterization and $^1H$ NMR spectroscopy was used for chemical structures determination of monomers and polymers. For all of the norbonene alkyl esters GPC data showed that when the amounts of endo isomers exceeded those of exo isomers decreased molecular weight polymers were obtained probably due to the decreased catalyst activity. Polymerizations were conducted by varying the monomer/catalyst mole ratios (100:1, 200:1, 300:1). When 300:1 monomer/catalyst ratio was employed it was possible to synthesize high molecular weight ($M_n=27500g/mol$), film forming polymer from exo-norbornene carboxylic acid octyl ester.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1296-1302
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• 2016

A hardware implementation of ultra-lightweight block cipher algorithm PRESENT that was specified as a block cipher standard for lightweight cryptography ISO/IEC 29192-2 is described in this paper. Two types of crypto-core that support master key size of 80-bit are designed, one is for encryption-only function, and the other is for encryption and decryption functions. The designed PR80 crypto-cores implement the basic cipher mode of operation ECB (electronic code book), and it can process consecutive blocks of plaintext/ciphertext without reloading master key. The PR80 crypto-cores were designed in soft IP with Verilog HDL, and they were verified using Virtex5 FPGA device. The synthesis results using $0.18{\mu}m$ CMOS cell library show that the encryption-only core has 2,990 GE and the encryption/decryption core has 3,687 GE, so they are very suitable for IoT security applications requiring small gate count. The estimated maximum clock frequency is 500 MHz for the encryption-only core and 444 MHz for the encryption/decryption core.

• Korean Journal of Environmental Agriculture
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• v.18 no.2
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• pp.179-184
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• 1999

To examine the relationship between air pollution and occurrence of disease in plants, we investigated the alteration of physiology and biochemistry of Ginkgo biloba by inoculating with Coniothyrium sp. and fumigating with 0.1 ${\mu}l/l\;SO_{2-}$ Visual damage did not appear but photosynthesis, $CO_2$ use efficiency(CUE) and water use efficiency(WUE) were reduced when G. biloba was exposed to $SO_{2-}$for 7days (8 hours a day). When inoculated with Coniothyrium sp., the seventies of damage in G. biloba showed a threefold difference between $SO_{2-}$ treatment (SI) and $SO_{2-}$ free treatment (SFI) at day 42 from initial inoculation. Little difference was observed in sugar contents that may be used pathogens feed, among control, SFI and SI. In spite of the reduction in photosynthetic rate, sugar contents and CUE were maintained. WUE was enhanced 13% more at SI than SFI. The $CO_2$fixation boosted because of enhanced WUE, and thus sugar synthesis was not affected. In addition, sugar transport seems to be retarded for some internal alteration. Consequently, the severity of SI was more serious than that of SFI because Coniothyrium sp. easily invades into the physical texture of G. biloba weakened by $SO_2$ fumigation and because sugar was accumulated in leaves of G. biloba.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.862-870
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• 1994

$Pb(NO_3)_2$, $Mg(NO_3)_2$ and $NbCl_5$ were used as starting materials and made into solutions. For $Pb(Mg_{1/3}Nb_{2/3})O_3$ composition, each solution measured was mixed and heated to $70^{\circ}C$ to resolved $PbCl_2$ precipitated at lower temperature coprecipitates were formed by adding oxine and ammonia gas under pH ranging 8 to 10, and the prepared coprecipitates were filtered and washed by distilled water. The $Pb(Mg_{1/3}Nb_{2/3})O_3$ powders were synthesized by calcination of coprecipitates at the temperature range of $700^{\circ}C$ to $1000^{\circ}C$, for 5hr. The average particle size of the synthesized powders showing spherical shape was $0.3{{\mu}m}$. The powders were formed to make pellets under pressure of $2000Kg/cm^2$, and the formed pellets were sintered at the temperature range of 1100 to $1200^{\circ}C$, for 5hr. The speciman sintered at $1200^{\circ}C$ showed theoretical density of 97.4%, dielectric constatnt of 17000 at 1kHz, and dielectric loss of 0.02% at 1kHz