• Magazine of the Korean Society of Agricultural Engineers
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• v.9 no.2
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• pp.1301-1305
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• 1967

Ground water flow can be studied with model test. Model test of ground water works are necessary for economic and safe design of the works. Also influence of the ground water flow to the durability and safety of hydraulic structures can be studied with this model. a. Sand model ; Water flow through porous media is the principle of sand model. Darcy's formula is the basic equation, $q=k{\frac{dh}{ds}}^{\circ}. The effect of the ground water flow on the grain system itself is represented with this model only. b. Hele-Shaw model ; In this model use is made of the viscous flow analogy. Viscous fluid such as glycerine flowing through two parallel plates depends on Poiseuille law, $q=-c{\frac{dh}{ds}}$. The analogue can be used vertically and horizontally. c. Heat model ; This is based on the analogy of the Fourier's law for heat conduction and Darcy's law for ground water flow. Especially unsteady problem can be studied with this model. A difficulty of the construction of this model is the isolation, which has to prevent losses of the heat. d. Electirc model ; Ohm's law for electric current is analogous to Darcy's law. Resistance material such as metal foil, graphite block, water with salt added, gelatine with salt added, ete. is connected to electric sources and resistor, and equi-voltage line is detected with galvanometer, $N_aCl$, $CuSo_4$, etc. are used as salt in the model. e. Membrane model ; This model is based on the facts that the deflection of a thin membrane obeys Laplace's equation if there is no load in the direction perpendicular to the membrane, and if the dellection is small.

• Journal of Plant Biotechnology
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• v.39 no.3
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• pp.146-153
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• 2012

In this study, the antioxidant property of leaf and callus extracts of five selected in vitro grown Ocimum species (Ocimum sanctum, Ocimum kilimandscharicum, Ocimum gratissimum, Ocimum basilicum, and Ocimum americanum) and their respective callus extracts was investigated. The callus cultures were successfully initiated on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxy acetic acid (2,4-D) (1mg L) combined with different concentrations (0.1-0.4 mg L) of kinetin as plant growth regulators. Total phenolic contents were estimated using the Folin-Ciocalteu reagent. 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power, $Fe^{2+}$ chelating activity, and ${\beta}$-carotenelinoleic acid bleaching assays were used to determine the biological effects of the extracts. Interestingly, all the callus extracts exhibited significant (p<0.05) increase in phenolic contents and antioxidant activity. Furthermore, a liner correlation was obtained between the total phenolic contents and free radical scavenging activity ($R^2$ = 0.783). The extracts of leaves and calluses of Ocimum species exhibited activity in all the in vitro antioxidant assays, but its extent was less potent that the positive controls butylated hydroxyl anisole (BHA) and ascorbic acid. A higher accumulation of phenolics in the callus extracts suggests that isolation of high-concentration materials with antioxidant activivity is possible from in vitro callus cultures rather than field-grown plant organs. Furthermore, these extracts may be used as an effective preservative in the food industry.

• Korean Journal of Veterinary Service
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• v.26 no.2
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• pp.121-128
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• 2003

This study was carried out to identify and investigate antimicrobial susceptibility for Mannheimuia haemolytical which is responsible for shipping fever. Samples were collected from nasal and lung of 100 adult healthy cattle which are slaughtered in Samsung meat corporation located in Incheon metropolitan city. lung lesion index have been investigated within 0-5 range according to Shewen and Willkie(Can J Vet Res 52:30-36, 1988). Eighty-seven of 100 cattle were under normal condition with 0-1 ranges. A total of 129 strains were collected from blood and tryptic soy agar. Among these strains, 100 strains were identified with Staphylococcus, Streptococcus and enterobacteria containing E coli. Biochemical and fermentation assay of arabinose, trehalose, xylose, mannose, mannitol, lactose and salicin were tested to identify with Mannheimia sp. for 7 strains shown haemolytic activity on blood agar. Five strains were identified with Mannheimia haemolytica and 2 strains were untyped. In seasonal survey, Mannheimia sp recovered from fall to winter(5 of 7) have been highly isolated rather than those from spring to summer(2 of 7). Mannheimiz haemolytica were susceptible to antibacterials tested in this study but more resistant to oxytetracycline and streptomycin.

• Korean Journal of Veterinary Service
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• v.26 no.4
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• pp.313-321
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• 2003

During the period of December 2000 to November 2001, a total of 419(10.9%) Salmonella was isolated from 3,850 slaughtered pig samples(2,732 lymph nodes and 1,118 caecal contents) in Korea. Three hundred and seventy(13.5%) and 49(4.4%) Salmonella were isolated from lymph nodes and caecal contents, respectively. In the isolation ratio of Salmonella spp originated from each class of season, summer(15.7%), autumn(11.5%), spring(10.0%) and winter(8.3%), in order. As the result of serotyping, B group(67.5%) were the most common, in order of C$_1$(14.6%), D$_1$(6.0%), C$_2$(4.1%) and E$_1$(3.3%). 32 serovars were found, the major serotypes were as follows; S typhimurium(21.7%), S schwarzengrund(16.0%), S derby(15.8%), S typhimurium variant copenhagen(9.8%), S enteritidis (6.0%) and S mbandaka(6.0%). All of the isolates were susceptible to norfloxacin and ofloxacin. The isolates were resistant in order of doxycycline(69.2%), tetracycline(68.7%), penicliin(54.9%) and streptomycin(52.5%).

• Korean Journal of Veterinary Research
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• v.52 no.3
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• pp.169-176
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• 2012

Probiotics colonize the intestines and exert an antibacterial effect on pathogens. Therefore, probiotics could be used as a preventive agent against lethal infections. To isolate probiotic microorganisms, 116 bacterial strains were isolated from healthy cow's milk and were subjected to Gram-stain, morphology and biochemical analyses, Vitek analysis, and 16S rRNA analysis. One of the strains identified as Bacillus (B.) thuringiensis 87 was found to grow very well at pH 4.0~7.0 and to be resistant to high concentrations of bile salts (0.3~0.9% w/v). B. thuringiensis was susceptible to the antibiotics used in the treatment of bovine mastitis, yet it exhibited an antimicrobial effect against Staphylococcus (S.) aureus 305. Moreover, it protected mice from experimental lethal infections of E. coli O55, Salmonella typhimurium 01D, and S. aureus 305 through a significant induction of interferon-${\gamma}$, even at four-week post-administration of B. thuringiensis. Although oral administration of B. thuringiensis 87 did not provide significant protection against these lethal challenges, these results suggest that B. thuringiensis 87 could be a feasible candidate as a probiotic strain.

• Korean Journal of Food Science and Technology
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• v.4 no.1
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• pp.1-5
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• 1972

This investigation was primarily carried out to establish the optimum conditions for the separation of sorbic acid, as an enzyme inhibitor, from dry mountain ash berries. The berries were crushed to $35{\sim}40\;mesh$, and leached with water to produce a reddish juice, which was concentrated to syrup after evaporation. Parasorbic acid was separated from the syrup by steam distillation in the presence of acid. In this study, the optimum experimental results for separation of parasorbic acid were obtained as follows : (1) the most applicable leaching time of the dry ash berries was about 6 hours at room temperature and less than 4 hours at $40^{\circ}C$ and (2) in steam distillation, after removal of malic acid, addition of 30 ml of sulfuric acid per 50 ml of syrup extracted from 100 g of the ash berries was very adequate. The purity of sorbic acid obtained experimentally through the isomerization technique was qualitatively examined by spectrophotometeric, paper chromatographic, and melting point measurements.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.963-966
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• 2007

The objectives of this study were to identity antioxidant substance in heated garlic juice (HGJ). We evaluated the antioxidant activities of heated garlic juice exposed to 120, 130, and $140^{\circ}C$ for 2 hr. The HGJ was partitioned using the solvents of hexane, chloroform, ethyl acetate, butanol, and water. The ethyl acetate fraction of HGJ treated at $130^{\circ}C$ for 2 hr showed strong antioxidant activity; this extract was isolated and purified using silica gel column chromatography and semi-preparative high-performance liquid chromatography. The structure of the purified compound was determined using spectroscopic methods, i.e., ultraviolet, mass spectrometry, infrared, $^1H$ NMR, $^{13}C$ NMR, DEPT, HMBC, and HMQC. The isolated compound was identified as thiacremonone (2,4-dihydroxy-2,5-dimethyl-thiophene-3-one). Thiacremonone showed strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, with a 50% inhibition concentration ($IC_{50}$) of $22.25{\pm}0.44\;{\mu}g/mL$, which is much higher than that of the antioxidants ascorbic acid ($30.06{\pm}0.42\;{\mu}g/mL$), ${\alpha}$-tocopherol ($71.30{\pm}0.97\;{\mu}g/mL$), and butylated hydroxyanisole ($50.54{\pm}0.94\;{\mu}g/mL$).

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.269-273
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• 2005

Five dibenzylbutyrolactones were isolated from a methanol extract of Arctii fructus (Arctium lappa L.) by bioassay-guided isolation, using the interleukin-l $\beta$ converting enzyme (caspase-l, ICE) production inhibitory assay in vitro. These compounds were spectroscopically identified as lappaol E (1), lappaol A (2), matairesinol (3), arctigenin (4), and arctiin (5). Among the compounds tested, arctigenin (4) showed the strongest inhibitory activity for ICE production in IL-$\beta$-induced proliferation of D 1 OS cells. Western blot analysis demonstrated that the arctigenin suppressed the expression of ICE protein in a dose-dependent manner. To estimate the biotransformation of Arctii fructus in vivo by human intestinal bacteria, we carried out an anaerobic incubation of the Arctii fructus extract with a human fecal suspension. From the HPLC analysis of metabolites, Arctiin (IC$_{50}$=74.2$\mu$g/ml), a major component of Arctii fructus, was transformed to aglycone, arctigenin (IC$_{50}$=12.5$\mu$g/ml), by human intestinal bacteria. The ICE production inhibitory activity of Arctii fructus would be much stronger in vivo than in vitro due to the biotransformation by human intestinal bacteria.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5375-5400
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• 2016

IOMMU is a hardware unit that is indispensable for DMA. Besides address translation and remapping, it also provides I/O virtual address space isolation among devices and memory access control on DMA transactions. However, currently commodity virtualization platforms lack of IOMMU virtualization, so that the virtual machines are vulnerable to DMA security threats. Previous works focus only on DMA security problem of directly assigned devices. Moreover, these solutions either introduce significant overhead or require modifications on the guest OS to optimize performance, and none can achieve high I/O efficiency and good compatibility with the guest OS simultaneously, which are both necessary for production environments. However, for simulated virtual devices the DMA security problem also exists, and previous works cannot solve this problem. The reason behind that is IOMMU circuits on the host do not work for this kind of devices as DMA operations of which are simulated by memory copy of CPU. Motivated by the above observations, we propose an IOMMU para-virtualization solution called PVIOMMU, which provides general functionalities especially DMA security guarantees for both directly assigned devices and simulated devices. The prototype of PVIOMMU is implemented in Qemu/KVM based on the virtio framework and can be dynamically loaded into guest kernel as a module, As a result, modifying and rebuilding guest kernel are not required. In addition, the device model of Qemu is revised to implement DMA access control by separating the device simulator from the address space of the guest virtual machine. Experimental evaluations on three kinds of network devices including Intel I210 (1Gbps), simulated E1000 (1Gbps) and IB ConnectX-3 (40Gbps) show that, PVIOMMU introduces little overhead on DMA transactions, and in general the network I/O performance is close to that in the native KVM implementation without IOMMU virtualization.

• Archives of Pharmacal Research
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• v.27 no.12
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• pp.1226-1232
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• 2004

Extracts from seventeen seaweeds were determined for tyrosinase inhibitory activity using mushroom tyrosinase with L-tyrosine as a substrate. Only one of them, Ecklonia stolonifera OKAMURA (Laminariaceae) belonging to brown algae, showed high tyrosinase inhibitory activity. Bioassay-guided fractionation of the active ethyl acetate (EtOAc) soluble fraction from the methanolic extract of E. stolonifera, led us to the isolation of phloroglucinol derivatives [phloroglucinol (1), eckstolonol (2), eckol (3), phlorofucofuroeckol A (4), and dieckol (5)]. Compounds 1~5 were found to inhibit the oxidation of L-tyrosine catalyzed by mushroom tyrosinase with $IC_{50}$ values of 92.8, 126, 33.2, 177, and 2.16 ${\mu}g$ /mL, respectively. It was compared with those of kojic acid and arbutin, well-known tyrosinase inhibitors, with $IC_{50}$ values of 6.32 and 112 ${\mu}g$ / mL, respectively. The inhibitory kinetics analyzed from Lineweaver-Burk plots, showed compounds 1 and 2 to be competitive inhibitors with $K_i$ of $2.3{\times}10^{-4}\;and\;3.1{times}10^{-4}$ M, and compounds 3~5 to be noncompetitive inhibitors with $K_i$ of $1.9{\times}10^{-5},\;1.4{\times}10^{-3}\;and\;1.5{\times}10^{-5}$ M, respectively. This work showed that phloroglucinol derivatives, natural compounds found in brown algae, could be involved in the control of pigmentation in plants and other organisms through inhibition of tyrosinase activity using L-tyrosine as a substrate.