• Korean Journal of Microbiology
• /
• v.54 no.4
• /
• pp.436-441
• /
• 2018

Ginseng are native traditional herbs, which exhibit excellent pharmacological activities. Probiotic Lactobacillus helveticus KII13 and Pediococcus pentosaceus strain KID7 were used for ginsenoside transformation by fermenting crude ginseng extract to enhance minor gisenoside content. Thin-layer chromatography (TLC) analysis of fermented ginseng extract showed that the minor ginsenosides Rg3, Rh1, and Rh2 were main products after 5 days of fermentation. HPLC analysis was performed to quantify the major and minor ginsenosides. The Rg3 peak appeared on the 3rd day while the appearance of Rh2 peak and Rh1 peak were observed on the 5th day. The co-culture of L. helveticus KII13 and P. pentosaceus KID7 converted major ginsenosides (Rb1 and Rg1) into minor ginsenosides (Rg3, Rh2, and Rh1).

• Journal of the Korean GEO-environmental Society
• /
• v.20 no.3
• /
• pp.31-38
• /
• 2019

To determine the optimum dynamic load test analysis for PCFT (Prestressed Concrete Filled steel Tube) hybrid composite piles that PCFT piles are connected to the top of PHC piles, the dynamic load tests and CAPWAP analyses were performed on two hybrid composite piles with steel pipe and PCFT piles as upper piles. The results of the dynamic load tests and CAPWAP analyses showed that the particle velocity measured in PCFT hybrid composite piles was equal to the wave speed of PHC piles when the strain gauges and accelerometers are attached to the surface of inner composite PHC pile after removing the steel pipe in the upper PCFT pile. In addition, when assuming that the material of that upper PCFT pile was the same as that of the lower PHC pile and the cross-sectional area of the steel pipe in upper PCFT pile was converted to that for concrete through the pile model (PM) in CAPWAP analysis, the accuracy of the CAPWAP analysis result for PCFT hybrid composite piles was very high.

• Journal of The Korean Society For Urban Railway
• /
• v.6 no.4
• /
• pp.417-426
• /
• 2018

Piezoelectric shunt is an electric type damper capable of reducing the vibration of the structure. Vibration generated at the natural frequency of the structure are converted into electrical energy through the piezoelectric material attached to the structure. Electric energy can be dissipated by thermal energy using piezoelectric shunt composed of inductor and resistance to reduce vibration. In this paper, the equation for the optimum inductance required to reduce the vibration of the cantilever beam was examined and the vibration of the aluminum cantilever was reduced by using finite element analysis and experiments. In the finite element analysis, the mode shape and the strain energy distribution were calculated to examine the mounting position, and the vibration reduction of the cantilever was calculated by adjusting the inductance and resistance circuit values. In addition, in the experiment, a variable inductor module was used to reduce the vibration occurring at a specific frequency of the cantilever. Finally, based on the results of the finite element analysis and the experiment, it was verified that the piezoelectric shunt can effectively reduce the vibration of the cantilever.

• Advances in nano research
• /
• v.15 no.5
• /
• pp.401-410
• /
• 2023

Vibration investigation of fluid-filled three layered cylindrical shells is studied here. A cylindrical shell is immersed in a fluid which is a non-viscous one. Shell motion equations are framed first order shell theory due to Love. These equations are partial differential equations which are usually solved by approximate technique. Robust and efficient techniques are favored to get precise results. Employment of the wave propagation approach procedure gives birth to the shell frequency equation. Use of acoustic wave equation is done to incorporate the sound pressure produced in a fluid. Hankel's functions of second kind designate the fluid influence. Mathematically the integral form of the Lagrange energy functional is converted into a set of three partial differential equations. It is also exhibited that the effect of frequencies is investigated by varying the different layers with constituent material. The coupled frequencies changes with these layers according to the material formation of fluid-filled FG-CSs. Throughout the computation, it is observed that the frequency behavior for the boundary conditions follow as; clamped-clamped (C-C), simply supported-simply supported (SS-SS) frequency curves are higher than that of clamped-simply (C-S) curves. Expressions for modal displacement functions, the three unknown functions are supposed in such way that the axial, circumferential and time variables are separated by the product method. Computer software MATLAB codes are used to solve the frequency equation for extracting vibrations of fluid-filled.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.8
• /
• pp.1348-1352
• /
• 2004

More than 200 Bifidobacterium sp. originated from human intestine were investigated for their ability to produce conjugated linoleic acid (CLA). Of the Bifidobacteria tested, 1 of culture type strain and 12 isolated strains from Korean infants showed CLA producing ability. cis-9, trans-11 octadecadienoic acid presented more than 90% of the total CLA isomers produced by the Bifidobacteria. CLA content in fermented milk by Bifidobacterium sp. KHU 141 increased by 39.6 mg/l00 g, which showed the potential use for producing fermented milk containing high content of CLA. In fermented milk, little changes showed in lauric acid, myristric acid, palmitic acid, oleic acid, and linolenic acid contents, whereas the content of linoleic acid (LA) decreased and the content of CLA increased. Bifidobacterium sp. KHU 141 converted 86.0% and 84.8% of LA consumed to CLA for 24 hr and 48 hr fermentation, respectively. Prolonging incubation from 24 to 48 hours did not appear to enhance CLA formation and CLA producing ability was stable whether bottle, test tube, or fermenter was used for making fermented milk by Bifidobacterium sp. KHU 141.

• Journal of Plant Biotechnology
• /
• v.37 no.3
• /
• pp.319-326
• /
• 2010

An interest in the production of seed-oil based fuel and raw materials, which comes from renewable plant sources, has been intrigued by the phenomenon of global warming and shortage of fossil fuels. Rapeseed (Brassica napus) is the most important oilseed crop, which produces seeds with 40% oil. It is desirable to develop genetically modified rapeseed producing oils, which can be easily converted to biodiesel. As an initial step for development of genetically modified rapeseed for the production of biofuels or bio-based materials, Korean rapeseed cultivars, Naehan, Youngsan, Tammi and Halla, were analyzed. Four Korean rapeseed cultivars produce 32 to 40% oil of seed dry weight, which is rich in oleic acid (more than 60 mole%). The cotyledonary petioles of rapeseed cultivar, Halla, were transformed using Agrobacterium tumefaciens strain GV3101, carrying the uidA gene encoding $\beta$-glucuronidase (GUS) as a reporter gene and the phosphinothricin acetyltransferase (PAT) gene as a selectable marker. The stable integration of PAT gene in the genome of transgenic rapeseeds was confirmed by PCR analysis. Expression of uidA gene in various rapeseed organs was determined by fluorometric assay and histochemical staining. Transformation efficiency of a Korean rapeseed Halla cultivar was 10.4%. Genetic inheritance of transgenes was confirmed in $T_2$ generation.

• Microbiology and Biotechnology Letters
• /
• v.44 no.4
• /
• pp.504-511
• /
• 2016

Lactulose, a synthetic disaccharide, has received increasing interest because of its role as a prebiotic that can increase the proliferation of Bifidobacterium and Lactobacillus spp. and enhance the absorption of calcium and magnesium. While the industrial production of lactulose is still mainly achieved by the chemical isomerization of lactose in alkaline media, this process has drawbacks including the need to remove catalysts and by-products, as well as high energy requirements. Recently, the use of cellobiose 2-epimerase (CE) has been considered an interesting alternative for industrial lactulose production. In this study, to develop a process for enzymatic lactulose production using CE, we screened improved mutant enzymes ($CS-H^RC^E$) from a library generated by an error-prone PCR technique. The thermostability of one mutant was enhanced, conferring stability up to $75^{\circ}C$, and its lactulose conversion yield was increased by 1.3-fold compared with that of wild-type CE. Using a recombinant Escherichia coli strain harboring a CS35 $H^RC^E$-expressing plasmid, we prepared cell beads immobilized on a Ca-alginate substrate and optimized their reaction conditions. In a batch reaction with 200 g/l lactose solution and the immobilized cell beads, lactose was converted into lactulose with a conversion yield of 43% in 2 h. In a repeated 38-plex batch reaction, the immobilized cell beads were relatively stable, and 80% of the original enzyme activity was retained after 4 cycles. In conclusion, we developed a reasonable method for lactulose production by immobilizing cells expressing thermostable CE. Further development is required to apply this approach at an industrial scale.

• Korean journal of applied entomology
• /
• v.41 no.2
• /
• pp.113-121
• /
• 2002

This study investigated the changes in the fitness of brown planthopper, NilapaHata lugens, to several rice varieties with different resistance background, after multi-generational selection on a resistant rice variety. A susceptible strain of brown planthopper (Dongjin-5) had been reared on the Chungchungbyeo with Bph1 resistance gene for three generations (Chungchung-G3) and six generations (Chungchung-G6), then the fitness change was evaluated by measuring their longevity, fecundity, preferences, and survivorships on the varieties with various background of resistance. After being selected three to six generations on Chungchungbyeo, feeding preference, adult longevity, and fecundity increased, where as nymphal period reduced when they were reared on various varieties with Bph1 gene. The egg Periods were not much different among the varieties fed on, except for the Chungchung-G6 on the rice varieties of Milyang63 (bph2 gene) and Gayabyeo (Bph1+bph2 gene). These results suggest that the susecptible Donajin-5 (Biotype-1) can be easily converted to a resistant biotype-2 capable of overcoming the resistant varieties with Bph 1 gene.

• Korean Journal of Plant Tissue Culture
• /
• v.22 no.2
• /
• pp.95-99
• /
• 1995

We have previously established a system for plant regeneration through somatic embryogenesis and Agrobacterium-mediated transformation of Korean ginseng. In this study to produce a fungus-resistant plant, we introduced a bean chitinase gene into ginseng using the transformation system. A binary vector pChi/748 was constructed by introducing the bean basic chitinase gene into EcoRI site of pGA748 which carries the CaMV 35S promoter governing the introduced gene and neomycin phosphotransferase II(NPT-II)gene as a positive selection marker. Cotyledonary explants were cocultured with A. tumefaciens strain LBA4404 harboring the binary vertor pChi/748 for 48 h, and transferred to MS medium supplemented with l mg/L2,4-D,0.1mg/L kinetin, 100 mg/L kanamycin, and 500mg/L carbenicillin. Kanamycin-resistant calli were formed on the cut surface of cotyledonary explants after one month of culture, and subsequently they gave rise to somatic embryos. Upon transfer onto medium containing 1 mg/L each of BA and GA$_3$, most of them converted to plantlets after 5 weeks of culture. The genomic DNA of eight kanamycin-resistant regenerants was subjected to polymerase chain reaction (PCR) using two specific 21-mer oligonucleotides derived from the chitinase gene. PCR-Southern blot analysis confirmed that the chitinase gene was incorporated into six out of the eight regenerants..

• KSBB Journal
• /
• v.15 no.2
• /
• pp.113-119
• /
• 2000

In order to produce xylitol with high yield, experiments were carried out to develope xylitol dehydrogenase (XDH) defective m mutant from Pichia stipitis and to investigate the xylit이 fermentation characteristics of mutant strain. After treatment of P s stipitis with EMS, mutant PXM-4 was selected based on the XDH activity and xylitol production capability. Among the tested c cosubstrates, galactose was selected as an adequate cosubstrate on xyl뻐I production of mutant PXM-4. With the increase of galactose concentration, xylitol production was decreased because the transport of xylose into cell was inhibited by g galactose. The optimal concentration of galactose for the production of xylitol using 20 g/L xylose was 20 g/L. Under this c condition, maximum concentration of xylitol and yield were 14.4 g/L and 97%, respectively. In order to prevent the inhibitory e effect of xylose transport by galactose, galactose was fed with low concentration and the concentration of xylitol produced w was increased up to 25 g/L. In the fermentation of corn cob hydrolyzate by mutant PXM-4, xylose was completely converted t to xylit이 with a 100% yield in 4 days culture.