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Search Results: 1 - 10 of 35454 matches for " Bo Geun Song "
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Preparation of Thiophene-Fused and Tetrahydroquinoline-Linked Cyclopentadienyl Titanium Complexes for Ethylene/α-Olefin Copolymerization
Sung Hun Kim,Ji Hae Park,Bo Geun Song,Seung-Woong Yoon,Min Jeong Go,Junseong Lee,Bun Yeoul Lee
Catalysts , 2013, DOI: 10.3390/catal3010104
Abstract: A synthetic scheme was developed for the large-scale preparation of a dimethylthiophene-fused and tetrahydroquinaldine-linked dimethylcyclopentadienyl titanium complex ( 2), which is a high-performance homogeneous Ziegler catalyst. 2,3,4,5-Tetramethyl-4,5-dihydrocyclopenta[ b]thiophen-6-one was prepared without chromatography purification on the 40-g scale in a laboratory setting, from which the ligand precursor for 2 was obtained in 65% yield on a 50-g scale in a one-pot without the need for chromatography purification. Metallation was achieved in a high yield (78%) through reaction of the dilithiated compound with TiCl 4. Many derivatives were prepared by employing the same synthetic scheme as applied for 2. Among them, the titanium complex prepared from 2-methyl-4,5-dimethyl-6-(2- n-butyl-2,3,4,5-tetrahydroquinolin-8-yl)-4 H-cyclopenta[ b]thiophene exhibited an exceptionally high activity. Under commercially relevant high-temperature polymerization conditions (160 °C), this compound showed a higher activity than 2 (126 × 10 6 g/molTi?h versus 72 × 10 6 g/molTi?h), albeit with the formation of a polymer of slightly lower molecular weight ( M w, 159,000 versus 218,000) and with a slightly lower 1-octene content (9.3 mol% versus 12 mol%).
Marginal turbid band and light blue crest, signs observed in magnifying narrow-band imaging endoscopy, are indicative of gastric intestinal metaplasia
An Jin,Song Geun,Kim Gwang,Park Do
BMC Gastroenterology , 2012, DOI: 10.1186/1471-230x-12-169
Abstract: Background Gastric intestinal metaplasia (IM) usually appears in flat mucosa and shows few morphologic changes, making diagnosis using conventional endoscopy unreliable. Magnifying narrow-band imaging (NBI) endoscopy enables evaluation of detailed morphological features that correspond with the underlying histology. The aim of this study was to investigate and clarify the diagnostic efficacy of magnifying NBI endoscopic findings for the prediction and diagnosis of IM. Methods Forty-seven patients were prospectively enrolled, and magnifying NBI examinations were performed in the lesser curvature of the midbody and the greater curvature of the upper body. The marginal turbid band (MTB) was defined as an enclosing white turbid band on the epithelial surface/gyri; light blue crest (LBC), as a fine, blue-white line on the crest of the epithelial surface/gyri. Immediately after observation under magnifying endoscopy, biopsy specimens were obtained from the evaluated areas. Results The degree of IM significantly increased with increasing MTB/LBC positivity (MTB-/LBC-, 0.00 ± 0.00; MTB+/LBC-, 0.44 ± 0.51; MTB+/LBC+, 0.94 ± 0.24; p < 0.001). Moderate-to-severe IM was more common in MTB+/LBC+ areas than in MTB+/LBC- areas (p < 0.001). For the diagnosis of IM, MTB had a sensitivity, specificity, and accuracy of 100%, 66.0%, and 81.7%, respectively, and the corresponding values for LBC were 72.1%, 96.0%, and 84.9%. Conclusion MTB and LBC observed in the gastric mucosa with magnifying NBI endoscopy are highly accurate indicators of the presence of IM. MTB likely represents a sign of early gastric IM, while LBC appears with progression to severe IM.
Two Volatile Organic Compounds Trigger Plant Self-Defense against a Bacterial Pathogen and a Sucking Insect in Cucumber under Open Field Conditions
Geun Cheol Song,Choong-Min Ryu
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14059803
Abstract: Systemic acquired resistance (SAR) is a plant self-defense mechanism against a broad-range of pathogens and insect pests. Among chemical SAR triggers, plant and bacterial volatiles are promising candidates for use in pest management, as these volatiles are highly effective, inexpensive, and can be employed at relatively low concentrations compared with agrochemicals. However, such volatiles have some drawbacks, including the high evaporation rate of these compounds after application in the open field, their negative effects on plant growth, and their inconsistent levels of effectiveness. Here, we demonstrate the effectiveness of volatile organic compound (VOC)-mediated induced resistance against both the bacterial angular leaf spot pathogen, Pseudononas syringae pv. lachrymans, and the sucking insect aphid, Myzus persicae, in the open field. Using the VOCs 3-pentanol and 2-butanone where fruit yields increased gave unexpectedly, a significant increase in the number of ladybird beetles, Coccinella septempunctata, a natural enemy of aphids. The defense-related gene CsLOX was induced by VOC treatment, indicating that triggering the oxylipin pathway in response to the emission of green leaf volatiles can recruit the natural enemy of aphids. These results demonstrate that VOCs may help prevent plant disease and insect damage by eliciting induced resistance, even in open fields.
DFT-based calculation of Coulomb blockade in molecular junction
Bo Song
Physics , 2007,
Abstract: Quantum transport through single molecules is very sensitive to the strength of the molecule-electrode contact. When a molecular junction weakly coupled to external electrodes, charging effects do play an important role (Coulomb blockade regime). In this regime, the non-equilibrium Green function is usually substituted with master equation approaches, which prevents the density functional theory from describing Coulomb blockade in non-equilibrium case. Last year, we proposed an Ansatz to combine the non-equilibrium Green function technique with the equation of motion method. With help of it, Coulomb blockade was obtained by non-equilibrium Green function, and completely agrees with the master equation results [Phys. Rev. B \textbf{76}, 045408 (2007)]. Here, by the Ansatz, we show a new way to introduce Coulomb blockade correction to DFT calculation in non-equilibrium case. And the characteristics of Coulomb blockade are obtained in the calculation of a $toy$ molecule correctly.
Enhanced TDMA Based Anti-Collision Algorithm with a Dynamic Frame Size Adjustment Strategy for Mobile RFID Readers
Kwang Cheol Shin,Seung Bo Park,Geun Sik Jo
Sensors , 2009, DOI: 10.3390/s90200845
Abstract: In the fields of production, manufacturing and supply chain management, Radio Frequency Identification (RFID) is regarded as one of the most important technologies. Nowadays, Mobile RFID, which is often installed in carts or forklift trucks, is increasingly being applied to the search for and checkout of items in warehouses, supermarkets, libraries and other industrial fields. In using Mobile RFID, since the readers are continuously moving, they can interfere with each other when they attempt to read the tags. In this study, we suggest a Time Division Multiple Access (TDMA) based anti-collision algorithm for Mobile RFID readers. Our algorithm automatically adjusts the frame size of each reader without using manual parameters by adopting the dynamic frame size adjustment strategy when collisions occur at a reader. Through experiments on a simulated environment for Mobile RFID readers, we show that the proposed method improves the number of successful transmissions by about 228% on average, compared with Colorwave, a representative TDMA based anti-collision algorithm.
The Optimal Environmental Ranges for Wetland Plants: Ⅱ. Scirpus tabernaemontani and Typha latifolia
Lee, Bo Ah,Gi Jin Kwon,Jae Geun Kim
Journal of Ecology and Field Biology , 2007,
Abstract: We studied the optimal ranges of water and soil characteristics for wetland plants, particularlyScirpus tabernaemontani (softstem bulrush) and Typha latifolia (broadleaf cattail), which are dominant specieswith potential for restoration of Korean wetlands. We observed vegetation in S. tabernaemontani and T. latifoliacommunities from the mid to late June, 2005, and measured characteristics of water environments such as waterdepth (WD), temperature (WT), conductivity (WC), and concentration of several ions (NO3--N, Ca2+, Na+, Mg2+,and K+), and characteristics of soil environments such as soil texture, organic matter (loss on ignition, LOI),conductivity, and pH. The S. tabernaemontani community was accompanied by Zizania latifolia (Manchurianwildrice), Persicaria thunbergii (Korean persicary), Actinostemma lobatum (lobed actinostemma), and Beckmanniasyzigachne (American slough grass), while the T. latifolia community was accompanied by P. thunbergii,T. angustifolia (narrowleaf cattail), and Glycine soja (wild soybean). We defined the optimal range for distribution(ORD) as the range that each plant was crowded. The optimal range of water characteristics for the S.tabernaemontani community was a WD 10~50 cm, WT 24.0~32.0℃, WC 100~500 μS/cm, NO3--N 0~60 ppb,K+ 0.00~1.50 ppm, Ca2+ 7.50~17.50 ppm, Na+ 2.50~12.50 ppm, and Mg2+ 3.00~7.00 ppm. In addition, theoptimal range of soil characteristics for the S. tabernaemontani community was a soil texture of loam, silty loam,and loamy sand, LOI 8.0~16.0%, pH 5.25~6.25, and conductivity 10~70 μS/cm. The optimal range of watercharacteristics for the T. latifolia community was a WD 10~30 cm, WT 22.5~27.5℃, WC 100~400 μS/cm,NO3--N 0~60 ppb, K+ 0.00~1.50 ppm, Ca2+ 0.00~17.50 ppm, Na+ 0.00~12.50 ppm, and Mg2+ 0.00~5.00 ppm,and the optimal range of soil characteristics for the T. latifolia community was a soil texture of loam, sandy loam,and silty loam, LOI 3.0~9.0%, pH 5.25~7.25, and conductivity 0~70 μS/cm.
Liquidity Expectation, Financing Ability and Credit Rating: Evidence from China  [PDF]
Shan Tian, Song Zhu, Bo Liu
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.35083
Abstract: Sovereign Credit Ratings of many countries and credit rating of dozens of firms has been downgraded since the latest financial crisis. However in China short-term financing market, the credit rating seems to show a counter-cyclical phe- nomenon. We find that when the market and the economy upsurge, the bond principal rating is relatively poor; when the market and economy downturn, the bond principal rating is relatively high. In other words, the ratings of short-term financing bills show a counter-cyclical phenomenon. We propose the liquidity hypothesis for this phenomenon that during the period of economic prosperity, market liquidity and capital is relatively abundant; therefore even the compa- nies with poor ratings have access to raise funds. When the market downturns and liquidity is poor, there are not enough funds in the market, thus the companies with poor ratings may fall to finance due to the lack of funds. Therefore, the liquidity of the market causes the bond rating to show a counter-cyclical phenomenon. Empirical research supports this hypothesis.
Testing Web Applications with Web Frameset and Browser Interactions
Bo Song,Shengbo Chen
Information Technology Journal , 2011,
Abstract: Software testing is a difficult task and testing Web applications may be more difficult, due to their characteristics. Web application is an interactive one since it came into being. How to model and test Web interactions is a challenge in software engineering. Web navigation models are useful to clarify requirements and specify implementation behaviors. Web frameset and Web browsers interactions are wildly used in todays Web applications. The behaviors of Web frameset and Web browser interactions changed the traditional Web navigation and influence the functionalities of Web applications. In this study, we took Web frameset and Web browsers interactions into account and proposed an approach to modeling the Web applications navigation and generating tests with Web framesets and browsers interactions. The construction formal semantics of structure composition of Web frameset is give out. Based on the formal semantics, the Web navigation with Web framesets is modeled. The Extended Browser Loading Model with Web frameset (EBLM) and the extended FSM is employed to formalize the navigation models with Web framesets and browsers interactions and a FSM Test-Tree (FSM-TT) is constructed using present construction algorithm. At last, test generation is given out which satisfies the corresponding coverage criteria. This study resolves the following research problems: (1) propose an approach to modeling Web applications with Web framesets and Web browsers interactions, (2) give the formal construction semantics of Web frameset and (3) formalize the navigation model and generating tests.
Period Distribution of Inversive Pseudorandom Number Generators Over Galois Rings
Bo Zhou,Qiankun Song
Mathematics , 2012,
Abstract: In 2009, Sol\'{e} and Zinoviev (\emph{Eur. J. Combin.}, vol. 30, no. 2, pp. 458-467, 2009) proposed an open problem of arithmetic interest to study the period of the inversive pseudorandom number generators (IPRNGs) and to give conditions bearing on $a, b$ to achieve maximal period, we focus on resolving this open problem. In this paper, the period distribution of the IPRNGs over the Galois ring $({\rm Z}_{p^{e}},+,\times)$ is considered, where $p>3$ is a prime and $e\geq 2$ is an integer. The IPRNGs are transformed to 2-dimensional linear feedback shift registers (LFSRs) so that the analysis of the period distribution of the IPRNGs is transformed to the analysis of the period distribution of the LFSRs. Then, by employing some analytical approaches, the full information on the period distribution of the IPRNGs is obtained, which is to make exact statistics about the period of the IPRNGs then count the number of IPRNGs of a specific period when $a$, $b$ and $x_{0}$ traverse all elements in ${\rm Z}_{p^{e}}$. The analysis process also indicates how to choose the parameters and the initial values such that the IPRNGs fit specific periods.
Period Distribution of Inversive Pseudorandom Number Generators Over Finite Fields
Bo Zhou,Qiankun Song
Mathematics , 2012,
Abstract: In this paper, we focus on analyzing the period distribution of the inversive pseudorandom number generators (IPRNGs) over finite field $({\rm Z}_{N},+,\times)$, where $N>3$ is a prime. The sequences generated by the IPRNGs are transformed to 2-dimensional linear feedback shift register (LFSR) sequences. By employing the generating function method and the finite field theory, the period distribution is obtained analytically. The analysis process also indicates how to choose the parameters and the initial values such that the IPRNGs fit specific periods. The analysis results show that there are many small periods if $N$ is not chosen properly. The experimental examples show the effectiveness of the theoretical analysis.
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