• Korean Journal of Veterinary Research
• /
• v.55 no.1
• /
• pp.53-56
• /
• 2015

Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis. This study was conducted to clarify the molecular characteristics of BLVs obtained from a specific region in Korea. Proviral BLVs were detected in anti-BLV antibody-positive blood samples by PCR. Env and gag fragments were sequenced and compared to previously published reference sequences. Analysis of the env gene sequence revealed that the YI strain was highly similar to genotype 1, including United States and Japanese strains. The gag gene sequence had the highest degree of similarity with a Japanese strain.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.09a
• /
• pp.290-292
• /
• 2004

Heavy metal contamination has been increased in aqueous environments near many industrial facilities, such as metal plating facilities, mining operations, and tanneries. The soils in the vicinity of many military bases are also reported to be contaminated and pose a risk of groundwater and surface water contamination with heavy metals. The biological removal of metals through bioaccumulation has distinct advantages over conventional methods; the process rarely produces undesirable or deleterious chemical byproducts, it is highly efficient, easy to operate and cost-effective in the treatment of large volumes of wastewater containing toxic heavy metals. In addition, a recent development of molecular biology shed light on the enhancing the microorganism's natural remediation capability as well as improving the current biological treatment. In this study, characteristics of the cell growth and heavy metal accumulation by Saccharomyces cerevisiae strains expressing phytochelatin syntahse (PCS) gene were studied in batch cultures. The AtCRFI gene was demonstrated to confer substantial increases in metal tolerance in yeast. PCS-expressing cells tolerated more Cd$^{2＋}$ than controls.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.5
• /
• pp.685-692
• /
• 2012

UV technology is widely used in water and wastewater treatment. Many researches have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on NOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics such as NOM. Pulsed UV treatment using UV flash lamp can be operated in the pulsed mode with much greater peak intensity. The pulse duration is typically in microseconds, whereas the interval between pulses is in the order of milliseconds. The high intensity of pulsed UV would mineralize NOM itself as well as change the characteristics of NOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of NOM. The objective of this study is to investigate the effect on NOM, chlorine residual, and chlorinated DBPs formation with pulsed UV treatment.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.37 no.2 s.110
• /
• pp.11-20
• /
• 2005

This study was carried out to investigate the influence of paper stock type and heat treatment on sizing effect. Various types of pulps were used to make handsheets sized internally with AKD(alkyl ketene dimer) and externally with CMC(carboxyl methyl cellulose). Most of the handsheets were treated with heat by dry oven $(100^{\circ}C,\;30min)$ to evaluate the effect of heat treatment on sizing development. Internal sizing development of newsprint was very bad, but the effect of heat treatment was much higher than those of NBKP, BCTMP. In case of surface sizing, newsprint was more effective compared to the other pulps. Considering above mentioned results, it seems that internal sizing slows down water into paper by molecular diffusion much more than capillary penetration, but surface sizing slows down capillary penetration. With regard to density, a higher thickness sheets showed high heat treatment effect on sizing, therefore it assumed that heat treatment effect on sizing had very close relationship with sheet density.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.9
• /
• pp.96-103
• /
• 1994

The GaAs epilayer was grown at low temperature (LT. 250.deg. C) by molecular beam epitaxy. The properties of the LTT GaAs, before and after Rapid Thermal Annealing(RTA), were analyzed by Reflection of High Energy Electron Diffraction (RHEED), Double Crystal X-ray(DCX), Raman spectroscopy, PL and Photo-Induced Current Transient Spectroscopy (PICTS). The LT GaAs before RTA, was analyzed by RHEED and DCX, with a result of an improved surface morphology under a relatively As-rich(As/Ga ratio :28) condition, and of an increased lattics parameter of 1.1 1.7% in comparison with a GaAs substrate. However DCX and Raman spectroscopy revealed that the expanded lattics parameter and the crystallinity of LT GaAs could be recovered after RTA. On the other hand, PL spectra indicated that LT GaAs after RTA showed low optical sensitivity unlike High Temperature(HT) GaAs, and that its surface morphology and crystallinity were corresponded with those of HT GaAs. Finally PICTS spectra proved the fact that low sensitivity of LT GaAs was due to the deep level defects (Ec-0.85eV) which were strogly formed by raising RTA temperature to 750.deg. C.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.37 no.2
• /
• pp.1-5
• /
• 2000

We have investigated dielectric properties of IMI-O LB films for the effect of complex concentration by electrical conductivity, dielectric constant and dielectric relaxation time at different frequencies. In the surface pressure-area$\pi$-A) isotherms for the increase of $FE^{3+}$ concentration, the molecular area was expanded with $FE^{3+}$concentration increase by electrostatic repulsion between the polymer chains and hydrophobic increase of ionic strength. In the I-V characteristics, it is found that the limiting area has effects on the change of conductivity And, the dielectric relaxation time decreased for increase of the $FE^{3+}$concentration.

• BMB Reports
• /
• v.31 no.1
• /
• pp.48-52
• /
• 1998

$p16^{INK4}$, which is a 16-kDa polypeptide protein, inhibits the catalytic activity of the CDK4-cyclinD complex to suppress rumor growth. Both unlabeled and isotope-labeled human tumor suppressor $p16^{INK4}$ protein were overexpressed and purified to characterize biochemical and structural properties. The purified p16 binds to monomeric GST-CDK4 and exists in a monomer conformation for several weeks at $4^{\circ}C$. The circular dichroism (CD) data indicates that p16 contains high percentage of ${\alpha}$-helix and that the helix percentage maximized at pH value of 7.0. One-and two-dimensional nuclear magnetic resonance (NMR) data suggest that purified p16 from our construct has a unique folded conformation under our experimental conditions and exhibits quite stable conformational characteristics.

• BMB Reports
• /
• v.31 no.1
• /
• pp.70-76
• /
• 1998

The final step in ethylene biosynthesis is catalyzed by the enzyme 1-aminocyclopropane-1-carboxylate (ACC) oxidase. ACC oxidase was extracted from mung bean hypocotyls and its biochemical characteristics were determined. In vitro ACC oxidase activity required ascorbate and $Fe^{2+}$, and was enhanced by sodium bicarbonate. Maximum specific activity (approximately 20 nl ethylene $h^{-1}$ mg $protein^{-1}$) was obtained in an assay medium containing 100 mM MOPS (pH 7.5), $25\;{\mu}M$ $FeSO_4$, 6 mM sodium ascorbate, 1 mM ACC, 5 mM sodium bicarbonate and 10% glycerol. The apparent $K_m$ for ACC was $80{\pm}3\;{\mu}M$. Pretreating mung bean hypocotyls with ethylene increased in vitro ACC oxidase activity twofold. ACC oxidase activity was strongly inhibited by metal ions such as $Co^{2+}$, $Cu^{2+}$, $Zn^{2+}$, and $Mn^{2+}$, and by salicylic acid. Inactivation of ACC oxidase by salicylic acid could be overcome by increasing the $Fe^{2+}$ concentration of the assay medium. The possible mode of inhibition of ACC oxidase activity by salicylic acid is discussed.

• ALGAE
• /
• v.25 no.2
• /
• pp.65-70
• /
• 2010

The genus Chaetoceros provides highly diversified diatoms in marine systems. Morphological descriptions of the genus are well-documented, yet the DNA taxonomy of Chaetoceros has not been satisfactorily established. Here, the molecular divergences of the 18S-28S rDNA of Chaetoceros were assessed. DNA similarities were relatively low in both 18S (93.1 $\pm$ 3.9%) and 28S rDNA (81.0 $\pm$ 4.6%). Phylogenies of the 18S, 28S rDNAs showed that Chaetoceros was divided according to individual species, clustering the same species into single clades. Statistical analysis with corrected genetic (p-) distance scores showed that nucleotide divergence of Chaetoceros 28S rDNA significantly differed from that of 18S rDNA (Student's t-test, p < 0.05). This finding suggests that the 28S rDNA may be treated as a more suitable marker for species-level taxonomic distinctions of Chaetoceros.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.10
• /
• pp.2712-2723
• /
• 1994

Numerical simulation of an axisymmetric ethylene-air jet diffusion flame has been carried out in order to investigate flame dynamics and soot formation. The model solves the time-dependent Navier-Stokes equations and includes models for soot formation, chemical reaction, molecular diffusion, thermal conduction, and radiation. Numerically FCT(Flux Corrected Transport) and DOM(Discrete Ordinate Method) methos are used for convection and radiation trasport respectively. Simulation was conducted for a 5 cm/sec fuel jet flowing into a coflowing air stream. The maximum flame temperature was found to be approximately 2100 K, and was located at an axial position of approximately 5 cm from the base of the flame. The maximum soot volume fraction was about $7{\times}10^{-7}$, and was located within the high temperature region where the fuel mole fraction ranges from 0.01 to 0.1. The buoyancy-driven low-frequency(12~13 Hz) structures convected along the outer region of the flame were captured. In case without radiation trasport, the maximum temperature was higher by 150 K than in case with radiation. Also the maximum soot volume fraction reached about $8{\times}10^{-6}$. As the the hydrocarbon fuel forms many soot particles, the radiation transport becomes to play a more important role.