• Journal of Distribution Science
• /
• v.11 no.10
• /
• pp.73-79
• /
• 2013

Purpose - This study examines the impact of oil price volatility on economic activities in Korea. The new millennium has seen a deregulation in the crude oil market, which invited immense capital inflow into Korea. It has also raised oil price levels and volatility. Drawing on the recent theoretical literature that emphasizes the role of volatility, this paper attends to the asymmetric changes in economic growth in response to the oil price movement. This study further examines several key macroeconomic variables, such as interest rate, production, and inflation. We come to the conclusion that oil price volatility can, in some part, explain the structural changes. Research design, data, and methodology - We use two methodological frameworks in this study. First, in regards to the oil price uncertainty, we use an Exponential-GARCH (Exponential Generalized Autoregressive Conditional Heteroskedasticity: EGARCH) model estimate to elucidate the asymmetric effect of oil price shock on the conditional oil price volatility. Second, along with the estimation of the conditional volatility by the EGARCH model, we use the estimates in a VECM (Vector Error Correction Model). The study thus examines the dynamic impacts of oil price volatility on industrial production, price levels, and monetary policy responses. We also approximate the monetary policy function by the yield of monetary stabilization bond. The data collected for the study ranges from 1990: M1 to 2013: M7. In the VECM analysis section, the time span is split into two sub-periods; one from 1990 to 1999, and another from 2000 to 2013, due to the U.S. CFTC (Commodity Futures Trading Commission) deregulation on the crude oil futures that became effective in 2000. This paper intends to probe the relationship between oil price uncertainty and macroeconomic variables since the structural change in the oil market became effective. Results and Conclusions - The dynamic impulse response functions obtained from the VECM show a prolonged dampening effect of oil price volatility shock on the industrial production across all sub-periods. We also find that inflation measured by CPI rises by one standard deviation shock in response to oil price uncertainty, and lasts for the ensuing period. In addition, the impulse response functions allude that South Korea practices an expansionary monetary policy in response to oil price shocks, which stems from oil price uncertainty. Moreover, a comparison of the results of the dynamic impulse response functions from the two sub-periods suggests that the dynamic relationships have strengthened since 2000. Specifically, the results are most drastic in terms of industrial production; the impact of oil price volatility shocks has more than doubled from the year 2000 onwards. These results again indicate that the relationships between crude oil price uncertainty and Korean macroeconomic activities have been strengthened since the year2000, which resulted in a structural change in the crude oil market due to the deregulation of the crude oil futures.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.4
• /
• pp.638-643
• /
• 2007

The full encoding sequence for human type II hexokinase (HXK II) was cloned into the E. coli expression vector pET 21b and expressed as a C-terminally hexahistidine-tagged protein in the BL2l (DE3) strain. The IPTG-induced HXK II approximately accounted for 17% of the total E. coli proteins, and 81% of HXK $II_{6{\times}His}$ existed in inclusion bodies. To improve the production of soluble recombinant HXK II protein, in the functionally active form, we used low temperature, and the osmotic stress expression method. When expressed at $18^{\circ}C$, about 83% of HXK $II_{6{\times}His}$ existed in the soluble fraction, which amounted to a 4.1-fold yield over that expressed at $37^{\circ}C$. The soluble form of HXK $II_{6{\times}His}$ was also highly produced in the presence of 1M sorbitol under the standard condition $(37^{\circ}C)$, which indicated that temperature downshift and low water potentials were required to improve the yield of active recombinant HXK II protein. The expressed protein was purified by metal chelate affinity chromatography performed in an IDA Excellose column charged with $Ni^{2+}$ ions, resulting in about 40mg recombinant HXK II protein obtained with purity over 89% from 51 of E. coli culture. The identity of HXK $II_{6{\times}His}$ was confirmed by Western blotting analysis. Taken together, using the stress-governed expression described in this study, human active HXK II can be purified in sufficient amounts for biochemical and biomedical studies.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.11
• /
• pp.2044-2051
• /
• 2017

The main pathological hallmark of Alzheimer's disease is the deposition of amyloid-beta ($A{\beta}$) peptides in the brain. $A{\beta}$ has been widely used to mimic several aspects of Alzheimer's disease. However, several characteristics of amyloid-induced Alzheimer's disease pathology are not well established, especially in mice. The present study aimed to develop a new Alzheimer's disease model by investigating how $A{\beta}$ can be effectively aggregated using prokaryotes and eukaryotes. To express the $A{\beta}42$ complex in HEK293 cells, we cloned the $A{\beta}42$ region in a tandem repeat and incorporated the resulting construct into a eukaryotic expression vector. Following transfection into HEK293 cells via lipofection, cell viability assay and western blotting analysis revealed that exogenous $A{\beta}42$ can induce cell death and apoptosis. In addition, recombinant His-tagged $A{\beta}42$ was successfully expressed in Escherichia coli BL21 (DE3) and not only readily formed $A{\beta}$ complexes, but also inhibited the proliferation of SH-SY5Y cells and E. coli. For in vivo testing, recombinant His-tagged $A{\beta}42$ solution ($3{\mu}g/{\mu}l$ in $1{\times}PBS$ containing $1mM\;Ni^{2+}$) was injected stereotaxically into the left and right lateral ventricles of the brains of C57BL/6J mice (n = 8). Control mice were injected with $1{\times}PBS$ containing $1mM\;Ni^{2+}$ following the same procedure. Ten days after the sample injection, the Morris water maze test confirmed that exogenous $A{\beta}$ caused an increase in memory loss. These findings demonstrated that $Ni^{2+}$ is capable of complexing the 50-kDa amyloid and that intracerebroventricular injection of $A{\beta}42$ can lead to cognitive impairment, thereby providing improved Alzheimer's disease models.

• The Korean Journal of Applied Statistics
• /
• v.30 no.6
• /
• pp.809-825
• /
• 2017

The number of TV entertainment shows is increasing. Competition among programs in the entertainment market is intensifying since cable channels air many entertainment TV shows. There is now a need for research on program ratings and the number of episodes. This study presents predictive models for entertainment TV show ratings and number of episodes. We use various data mining techniques such as linear regression, logistic regression, LASSO, random forests, gradient boosting, and support vector machine. The analysis results show that the average program ratings before the first broadcast is affected by broadcasting company, average ratings of the previous season, starting year and number of articles. The average program ratings after the first broadcast is influenced by the rating of the first broadcast, broadcasting company and program type. We also found that the predicted average ratings, starting year, type and broadcasting company are important variables in predicting of the number of episodes.

• Journal of Plant Biotechnology
• /
• v.34 no.4
• /
• pp.375-380
• /
• 2007

This study was conducted to develop herbicide-resistance domestic maize plants by introducing the CP4 5-enol-pyruvylshikimate-3-phosphate synthase (CP4 EPSPS) gene using Agrobacterium tumefaciens-mediated immature embryo transformation. Immature embryos of five genotypes (HW1, KL103, HW3, HW4, HW7) were co-cultivated with strains Agrobacterium tumefaciens (strain C58C1) containing the binary vector (pCAMBIA2300) carrying Ubiquitin promoter-CP4 EPSPS gene and Cauliflower mosaic virus 35S (CaMV35S) promoter-nptll gene conferring resistance to paromomycin as a selective agent. The presence and expression of CP4 EPSPS transgene were confirmed by PCR, RT-PCR and Northern blot analysis, respectively. Also, the resistance to glyphosate in the transgenic maize ($T_1$) was analyzed by shikimate accumulation assay. The frequency (%) of paromomycin-resistance callus was 0.37, 0.03, 2.20, 2.37, and 0.81% in pure lines HW1, KL103, HW3, HW4 and HW7, respectively. EPSP transgene sequences were amplified in putative transgenic plants that regenerated from paromomycin-resistance calli of two inbred lines (HW3, HW4). Of them, RT-PCR and Northern blot analyses revealed that the transgene was only expressed in two transgenic events (M266, M104) of HW4 inbred line, and a mild glyphosate resistance of transgenic event (M266) was confirmed by the lower shikimate accumulation in leaf segments. These results demonstrate that transgenic maize with herbicide-resistance traits in Korean genotype can be genetically obtained.

• Journal of Plant Biotechnology
• /
• v.38 no.1
• /
• pp.42-48
• /
• 2011

Chloroplast genetic engineering of higher plants offers several unique advantages compared with nuclear genome transformation, such as high levels of transgene expression, a lack of position effect due to site-specific transgene integration by homologous recombination, multigene engineering in a single transformation event and reducing risks of gene flow via pollen due to maternal inheritance. We established a reproducible chloroplast transformation system of potato using a tobacco specific plastid transformation vector, pCtVG (trnI-Prrn-aadA-mgfp-TpsbA-trnA). Stable transgene integration into chloroplast genomes and the homoplasmic state of the transgenome were confirmed by PCR and Southern blot analyses. Northern, immunoblot analysis, and GFP fluorescence imaging revealed high expression and accumulation of GFP in the plastids of potato leaves. This system would provide new opportunities for genetic improvement and mass production of value added foreign proteins in this crop.

• Information Systems Review
• /
• v.18 no.2
• /
• pp.23-38
• /
• 2016

Previous studies on information systems (IS) and finance suggest that information on stock message boards influence the investment decisions of individual investors. However, how information on online stock message boards influences an individual investor's buy or sell decisions is unclear. To address this research question, we investigate the relationship between a number of posts on stock message boards and order imbalance in stock markets. Order imbalance is defined as the difference between the daily sum of buy-side shares traded and the daily sum of sell-side shares traded. Therefore, order imbalance can suggest the direction of trades and the strength of the direction with trading volumes. In this regard, this study examines how the number of posts (information on stock message boards) influences order imbalance (stock trading behavior). We collected about 46,077 messages of 40 companies on the Korea Composite Stock Price Index from Paxnet, the most popular Korean online stock message board. The messages we collected were divided based on in-trading and after-trading hours to examine the relationship between the numbers of posts and trading volumes. We also collected order imbalance data on individual investors. We then integrated the balanced panel data sets and analyzed them through vector regression. We found that the number of posts on online stock message boards is positively related to prior order imbalance. We believe that our findings contribute to knowledge in IS and finance. Furthermore, this study suggests that investors should carefully monitor information on stock message boards to understand stock market sentiments.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.31 no.1
• /
• pp.1-8
• /
• 2011

Molecular techniques such as genetic transformation are powerful tools that can be used for the genetic modification of warm-season grasses. The P. meyerianum with high regeneration ability was used for establishing an Agrobacterium-mediated transformation system. We investigated various factors affecting Agrobacterium infection by examining GUS gene expression of pCAMBIA1304 vector. Among various concentration of acetosyringone and betaine tested for inoculation and co-cultivation, 10 mg/L acetosyringone and 60 mg/L betaine resulted in the highest transformation frequency in terms of GUS expression. The calli of 4 species of Panicum spp. with excellent tissue culture response were inoculated with Agrobacterium under the optimal infection conditions. The high activity of GUS gene was observed in all species and hygromycin-resistant calli expressing GFP were obtained in P. meyerianum, P. longijubatum, P. stapfianum and guineagrass Noh-PL1. Co-cultivated calli were transferred onto the selection medium containing hygromycin, and the hygromycin resistant calli were selected after 3 months. Hygromycin-resistant plantlets were then successfully regenerated from the calli and grown in a greenhouse. We confirmed stable insertion of hpt gene among the hygromycin-resistant plantlets of P. meyerianum by PCR analysis.

• Journal of Life Science
• /
• v.19 no.6
• /
• pp.809-817
• /
• 2009

The phenotypes associated with a gene function are often the best clue to its role in the plant. Transgenic plants ectopically expressing or suppressing a gene can provide useful information related to the gene function. In this study, we constructed three vectors - pFGL571, pFGL846 and pFGL847 - for the Agrobacterium-mediated ectopic expression of plant genes using pPZP211 and modified CaMV 35S, UBQ3 or UBQ10 promoters. The three vectors have several merits such as small size, high copy in bacteria, enough restriction enzyme sites in multi cloning sites and nucleotide sequence information. Analysis of transgenic plants containing GUS or sGFP reporter genes under the control of modified CaMV 35S, UBQ3 or UBQI0 promoter revealed that all of the three promoters showed high activities during most developmental stages after germination and in floral organs. Furthermore, we generated a RNAi module vector, pFGL727, to suppress plant gene expressions and confirmed that pFGL727 is useful for the suppression of a gene expression using rice transgenic plants. Taken together, our new vectors would be very useful for the ectopic expression or the suppression of plant genes.

• Journal of Life Science
• /
• v.12 no.2
• /
• pp.188-199
• /
• 2002

A gene coding for xylanase from thermo-tolerant Bacillus pumilus TX703 was cloned into Escherichia coli DH5 $\alpha$ using pUC19. Among 7,400 transformants, four transformants showed clear zones on the detection agar plates containing oat-spells xylan. One of them which showed highest xylanase activity was selected and its recombinant plasmid, named pXES106, was found to carry 2.24 kb insert DNA fragment. When the nucleotide sequence of the cloned xylanase gene (xynK) was determined, xynK gene was found to consist of 1,227 base-pair open reading frame coding for a polypeptide of 409 amino acids with a deduced molecular weight of 48 kDa. The coding sequence was preceded by a putative ribosome binding site, the transcription initiation signals, and cia-acting catabolite responsive element. The deduced amino acids sequence of xylanase is similar to those of the xylanases from Hordeum vulgare (barley) and Clostridium thermocellum, with 39 and 31% identical residues, respectively. The amino acids sequence of this xylanase was quite different from those of the xylanases from other Bacillus species.