Showing papers by "Korea University published in 2004"
TL;DR: EEG abnormalities of AD patients are characterized by slowed mean frequency, less complex activity, and reduced coherences among cortical regions, suggesting that the EEG has utility as a valuable tool for differential and early diagnosis of AD.
1,100 citations
TL;DR: In this paper, an environmentally benign process for the production of biodiesel from VOs using heterogeneous catalyst was developed, and the basic strength of Na/NaOH/γ-Al2O3 catalyst was estimated and the correlation with the activity towards transesterification was proposed.
706 citations
TL;DR: In this paper, the authors measured the centrality dependence of transverse momentum distributions and particle yields at the PHENIX experiment at the Relativistic Heavy Ion Collider (HIC).
Abstract: The centrality dependence of transverse momentum distributions and yields for ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}},{K}^{\ifmmode\pm\else\textpm\fi{}},p$, and $\overline{p}$ in $\text{Au}+\text{Au}$ collisions at $\sqrt{{s}_{NN}}=200\phantom{\rule{0.3em}{0ex}}\text{GeV}$ at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider. We observe a clear particle mass dependence of the shapes of transverse momentum spectra in central collisions below $\ensuremath{\sim}2\phantom{\rule{0.3em}{0ex}}\text{GeV}∕c$ in ${p}_{T}$. Both mean transverse momenta and particle yields per participant pair increase from peripheral to midcentral and saturate at the most central collisions for all particle species. We also measure particle ratios of ${\ensuremath{\pi}}^{\ensuremath{-}}∕{\ensuremath{\pi}}^{+}$, ${K}^{\ensuremath{-}}∕{K}^{+}$, $\overline{p}∕p$, $K∕\ensuremath{\pi}$, $p∕\ensuremath{\pi}$, and $\overline{p}∕\ensuremath{\pi}$ as a function of ${p}_{T}$ and collision centrality. The ratios of equal mass particle yields are independent of ${p}_{T}$ and centrality within the experimental uncertainties. In central collisions at intermediate transverse momenta $\ensuremath{\sim}1.5--4.5\phantom{\rule{0.3em}{0ex}}\text{GeV}∕c$, proton and antiproton yields constitute a significant fraction of the charged hadron production and show a scaling behavior different from that of pions.
622 citations
TL;DR: In this paper, thin and flexible composite films of raw or purified multiwalled carbon nanotube (MWCNT) with various mass fractions and poly(methylmethacrylate) (PMMA) were synthesized for electromagnetic interference (EMI) shielding material.
Abstract: Thin and flexible composite films of raw or purified multiwalled carbon nanotube (MWCNT) with various mass fractions and poly(methylmethacrylate) (PMMA) were synthesized for electromagnetic interference (EMI) shielding material. From scanning electron microscopy and high-resolution transmission electron microscopy photographs, we observed the formation of a conducting network through MWCNTs in an insulating PMMA matrix and the existence of an Fe catalyst in MWCNTs. The dc conductivity (σdc) of the systems increased with increasing MWCNT mass fraction, showing typical percolation behavior. The measured EMI shielding efficiency (SE) of MWCNT–PMMA composites by using the extended ASTM D4935-99 method (50 MHz–13.5 GHz) increased with increasing MWCNT mass fraction as σdc. The highest EMI SE for raw MWCNT–PMMA composites was ∼27 dB, indicating commercial use for far-field EMI shielding. The contribution of absorption to total EMI SE of the systems is larger than that of reflection. Based on magnetic permeabili...
569 citations
TL;DR: The findings show that SDB is a common problem in the Korean adult population and understanding and treatment of SDB may be essential in terms of intervention to reduce the risk of related medical problems.
Abstract: With many epidemiologic studies made to establish the prevalence of sleep-disordered breathing (SDB) and obstructive sleep apnea syndrome (OSAS) in Western countries, no such data have been reported in Korea. The purpose of this study was to examine the prevalence of SDB and OSAS, and their related factors in Korean adults aged 40-69 years. Among the total of 5,020 participants at the baseline examination of the Korean Health and Genome Study, a random sample of 457 men and women was studied with employment of overnight full polysomnography to determine the prevalence of SDB and OSAS. The prevalence of SDB (apnea-hypopnea index > or = 5) was 27% and 16% in men and women, respectively. When OSAS was defined by an apnea-hypopnea index > or = 5 plus excessive daytime sleepiness, its prevalence was 4.5% in men and 3.2% in women. Logistic regression analyses showed that sex, body mass index, and hypertension were closely associated with the risk of SDB. Our findings show that SDB is a common problem in the Korean adult population. Understanding and treatment of SDB may be essential in terms of intervention to reduce the risk of related medical problems.
463 citations
456 citations
TL;DR: The higher enzyme activities produced by A. niger KK2 is a significant advantage from the viewpoint of practical saccharification reaction and might be applied to pulp and paper industry, feed industry and chemical industry.
428 citations
TL;DR: The CBR estimating model performed better than the MRA, neural networks, and case-based reasoning models with respect to long-term use, available information from result, and time versus accuracy tradeoffs.
419 citations
TL;DR: In this article, the authors reported the observation of the X(3872) in the J/psipi(+)pi(-) channel with decaying to mu(+)mu(-), in p (p) over bar collisions at roots=1.96 TeV.
Abstract: We report the observation of the X(3872) in the J/psipi(+)pi(-) channel, with J/psi decaying to mu(+)mu(-), in p (p) over bar collisions at roots=1.96 TeV. Using approximately 230 pb(-1) of data collected with the Run II D0 detector, we observe 522+/-100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9+/-3.1(stat)+/-3.0(syst) MeV/c(2). We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the psi(2S) state.
418 citations
TL;DR: This study shows that the more sophisticated classi%ers give better performances than classical methods such as kNN, DLDA, DQDA and the choice of gene selection method has much impact on the performance of the classi-cation methods, and thus theclassi%cation methods should be considered together with the gene selection criteria.
410 citations
TL;DR: Through the detailed comparisons of several chloroplast genomes, evolutionary hotspots predominated by the inversion end points, indel mutation events, and high frequencies of base substitutions were identified.
Abstract: The nucleotide sequence of Korean ginseng (Panax schinseng Nees) chloroplast genome has been completed (AY582139). The circular double-stranded DNA, which consists of 156,318 bp, contains a pair of inverted repeat regions (IRa and IRb) with 26,071 bp each, which are separated by small and large single copy regions of 86,106 bp and 18,070 bp, respectively. The inverted repeat region is further extended into a large single copy region which includes the 5' parts of the rpsl9 gene. Four short inversions associated with short palindromic sequences that form stem-loop structures were also observed in the chloroplast genome of P. schinseng compared to that of Nicotiana tabacum. The genome content and the relative positions of 114 genes (75 peptide-encoding genes, 30 tRNA genes, 4 rRNA genes, and 5 conserved open reading frames [ycfs]), however, are identical with the chloroplast DNA of N. tabacum. Sixteen genes contain one intron while two genes have two introns. Of these introns, only one (trnL-UAA) belongs to the self-splicing group I; all remaining introns have the characteristics of six domains belonging to group II. Eighteen simple sequence repeats have been identified from the chloroplast genome of Korean ginseng. Several of these SSR loci show infra-specific variations. A detailed comparison of 17 known completed chloroplast genomes from the vascular plants allowed the identification of evolutionary modes of coding segments and intron sequences, as well as the evaluation of the phylogenetic utilities of chloroplast genes. Furthermore, through the detailed comparisons of several chloroplast genomes, evolutionary hotspots predominated by the inversion end points, indel mutation events, and high frequencies of base substitutions were identified. Large-sized indels were often associated with direct repeats at the end of the sequences facilitating intra-molecular recombination.
TL;DR: Reactive dye solutions have higher applicability of Fenton oxidation than disperse dye solutions due to their higher solubility, lower suspended solids concentrations and higher SCOD/TCOD ratios.
TL;DR: It is shown that RASSF1A regulates the stability of mitotic cyclins and the timing of mitosis and the regulation of both APC–Cdc20 activity and mitotic progression.
Abstract: The tumour suppressor gene RASSF1A is frequently silenced in lung cancer and other sporadic tumours as a result of hypermethylation of a CpG island in its promoter1,2,3,4,5,6. However, the precise mechanism by which RASSF1A functions in cell cycle regulation and tumour suppression has remained unknown. Here we show that RASSF1A regulates the stability of mitotic cyclins and the timing of mitotic progression. RASSF1A localizes to microtubules during interphase and to centrosomes and the spindle during mitosis. The overexpression of RASSF1A induced stabilization of mitotic cyclins and mitotic arrest at prometaphase. RASSF1A interacts with Cdc20, an activator of the anaphase-promoting complex (APC), resulting in the inhibition of APC activity. Although RASSF1A does not contribute to either the Mad2-dependent spindle assembly checkpoint or the function of Emi1 (ref. 1), depletion of RASSF1A by RNA interference accelerated the mitotic cyclin degradation and mitotic progression as a result of premature APC activation. It also caused a cell division defect characterized by centrosome abnormalities and multipolar spindles. These findings implicate RASSF1A in the regulation of both APC–Cdc20 activity and mitotic progression.
TL;DR: A hot pepper (Capsicum annuum) cDNA clone encoding pathogenesis-related protein 10 (CaPR-10) was isolated by differential screening of a cDNA library prepared from pepper leaves inoculated with tobacco mosaic virus pathotype (TMV-P0) as discussed by the authors.
Abstract: A hot pepper (Capsicum annuum) cDNA clone encoding pathogenesis-related protein 10 (CaPR-10) was isolated by differential screening of a cDNA library prepared from pepper leaves inoculated with tobacco mosaic virus pathotype (TMV-P0). CaPR-10 transcripts were induced in the incompatible interaction with TMV-P0 or Xanthomonas campestris pv. vesicatoria (Xcv) but not induced in the compatible interaction. Characterization of enzymatic properties of CaPR-10 indicated that the recombinant protein exhibits a ribonucleolytic activity against TMV RNA, as well as against pepper total RNA, and shows its putative antiviral activity in several conditions. The CaPR-10 protein existed at very low level in leaf tissue but was dramatically induced as soon as plants were inoculated with TMV-P0, and this was correlated with the increase of its ribonucleolytic activity. Immunoblot analysis and pull-down assays using proteins extracted from pepper leaves showed that TMV-P0 inoculation led to the phosphorylation of CaPR-10, a modification that should affect its capacity for RNase function. We present data that the induction and subsequent phosphorylation of CaPR-10 increased its ribonucleolytic activity to cleave invading viral RNAs, and this activity should be important to its antiviral pathway during viral attack in vivo.
TL;DR: Choi et al. as mentioned in this paper investigated the relationship between consumer values of eating-out and the importance of fast food restaurant attributes in Korea and found that the hedonic value more influenced buying frequency than the utilitarian value.
TL;DR: In this paper, the photoresponse of ZnO nanowires under continuous illumination of light with above- or below-gap energies was found to be slow, which indicates that the photocurrent in the nanwires is surface-related rather than bulk-related.
Abstract: ZnO nanowires were grown between two Au electrodes on an Al2O3-deposited Si wafer. Photoresponse, photoresponse spectrum, and current–voltage (I–V) studies were performed for the investigation into photoconduction mechanism in these nanowires. The photoresponse of the nanowires under the continuous illumination of light with above- or below-gap energies was slow, which indicates that photocurrent in the nanowires is surface-related rather than bulk-related. The photoresponse spectrum represents the above- and below-gap absorption bands for the photocurrents. The I–V characteristics under the illumination of the above-gap light are ohmic, but the characteristics under the illumination of the below-gap light are Schottky. This observation indicates that the above-gap light lowers the potential barrier built in the contact between the ZnO nanowires and electrodes, but that the below-gap light does not lower the potential barrier.
TL;DR: In this article, a reconfigurable microstrip antenna with switchable polarization sense is proposed, consisting of a corner-truncated square radiating patch, four small triangular conductors, and a microstrip line feed.
Abstract: A novel reconfigurable microstrip antenna with switchable polarization sense is proposed. The proposed antenna has a simple structure, consisting of a corner-truncated square radiating patch, four small triangular conductors, and a microstrip line feed. Using independently biased PIN diodes on the patch, it can produce linear polarization, or left- or right-hand circular polarization according to bias voltages. From the measured results, low cross-polarization levels when operated in the linear state and good axial ratios in the circular state are observed.
TL;DR: In this paper, the authors investigated nitrogen doping effects on the structure and crystallinity of bamboo-shaped multiwalled carbon nanotubes (BS-MWNTs) by means of x-ray photoemission spectroscopy (XPS) and transmission electron microscopy.
Abstract: We have investigated nitrogen doping effects on the structure and crystallinity of bamboo-shaped multiwalled carbon nanotubes (BS-MWNTs) by means of x-ray photoemission spectroscopy (XPS) and transmission electron microscopy. By controlling the NH3/C2H2 flow ratio during the chemical vapor deposition, the nitrogen concentrations of 0.4% to 2.4% were obtained. According to the XPS measurements, the increasing nitrogen concentration gave rise to an increase of the N-sp3 C bonds as well as the deterioration of the crystallinity of the BS-MWNTs. Besides, the N-sp3 C bonds were found to prevail over the N-sp2 C bonds above 5% nitrogen concentration. At higher nitrogen concentrations, the BS-MWNTs showed shorter compartment distances, presumably due to the suppressed surface diffusion of carbon on the catalyst particles.
TL;DR: The ACE-Asia aerosols are composed not only of desert dust but also of soil dust, smoke from biomass and refuse burning, and emissions from fossil fuel use in urban areas as discussed by the authors.
Abstract: [1] The organic compound tracers of atmospheric particulate matter, as well as organic carbon (OC) and elemental carbon (EC), have been characterized for samples acquired during the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) from Gosan, Jeju Island, Korea, from Sapporo, Japan, and from Chichi-jima Island in the western North Pacific, as well as on the National Oceanic and Atmospheric Administration R/V Ronald H. Brown. Total extracts were analyzed by gas chromatography–mass spectrometry to determine both polar and aliphatic compounds. Total particles, organic matter, and lipid and saccharide compounds were high during the Asian dust episode (early April 2001) compared to levels at other times. The organic matter can be apportioned to seven emission sources and to significant oxidation-producing secondary products during long-range transport. Terrestrial natural background compounds are vascular plant wax lipids derived from direct emission and as part of desert sand dust. Fossil fuel utilization is obvious and derives from petroleum product and coal combustion emissions. Saccharides are a major polar (water-soluble) carbonaceous fraction derived from soil resuspension (agricultural activities). Biomass-burning smoke is evident in all samples and seasons. It contributes up to 13% of the total compound mass as water-soluble constituents. Burning of refuse is another source of organic particles. Varying levels of marine-derived lipids are superimposed during aerosol transport over the ocean. Secondary oxidation products increase with increasing transport distance and time. The ACE-Asia aerosols are composed not only of desert dust but also of soil dust, smoke from biomass and refuse burning, and emissions from fossil fuel use in urban areas.
TL;DR: Findings provide support to the study's proposition that power-dependence relationships in a keiretsu influence member firms' appropriation of group affiliation benefits in pursuing diversification strategies.
Abstract: Conceptualizing the keiretsu as a power-dependence system, we propose that benefits accruing from keiretsu affiliation differ across member firms, depending on their power in (or dependence on) the keiretsu. By integrating power with governance and internal market perspectives on group affiliation, we develop and find general support for the hypotheses that powerful keiretsu member firms are able to place more emphasis on growth in pursuing product and international diversification, whereas less powerful keiretsu member firms are subject to strong monitoring and emphasize profitability. These findings provide support to the study's proposition that power-dependence relationships in a keiretsu influence member firms' appropriation of group affiliation benefits in pursuing diversification strategies. Copyright © 2004 John Wiley & Sons, Ltd.
TL;DR: A comprehensive framework for managing various semantic conflicts is proposed that provides a unified view of the underlying representational and reasoning formalism for the semantic mediation process and suggests that correct identification and construction of both schema and ontology-schema mapping knowledge play very important roles in achieving interoperability at both the data and schema levels.
Abstract: Interoperability is the most critical issue facing businesses that need to access information from multiple information systems. Our objective in this research is to develop a comprehensive framework and methodology to facilitate semantic interoperability among distributed and heterogeneous information systems. A comprehensive framework for managing various semantic conflicts is proposed. Our proposed framework provides a unified view of the underlying representational and reasoning formalism for the semantic mediation process. This framework is then used as a basis for automating the detection and resolution of semantic conflicts among heterogeneous information sources. We define several types of semantic mediators to achieve semantic interoperability. A domain-independent ontology is used to capture various semantic conflicts. A mediation-based query processing technique is developed to provide uniform and integrated access to the multiple heterogeneous databases. A usable prototype is implemented as a proof-of-concept for this work. Finally, the usefulness of our approach is evaluated using three cases in different application domains. Various heterogeneous datasets are used during the evaluation phase. The results of the evaluation suggest that correct identification and construction of both schema and ontology-schema mapping knowledge play very important roles in achieving interoperability at both the data and schema levels.
TL;DR: In this paper, ZnO nanorods were grown on SiO2/Si substrates by a sol-gel method at low temperatures of around T=95 °C.
Abstract: ZnO nanorods were grown on SiO2/Si substrates by a sol-gel method at low temperatures of around T=95 °C. The diameters and the lengths of ZnO nanorods increased at high concentrations of zinc nitrate hexahydrate and methenamine solution. Current–voltage characteristics of the ZnO nanorods network followed a typical nonlinear behavior with significant photoresponse below λ<400 nm in air, and the conductance was enhanced in vacuum with negligible photoresponse. In photoluminescence (PL) and photocurrent (PC) spectra, the PL peak (λpeak=380 nm and 3.26 eV) did not match the PC edge (λedge=400 nm and 3.1 eV), indicating the nondirect band-gap transition in photocurrent. The origin of the photocurrent was discussed from the point of the influence of the desorption of adsorbed water molecules on the surface or inside the ZnO nanorods.
TL;DR: Based on a user survey, this study of the ISO/IEC 9126 standard helps clarity quality attributes and provides guidance for the resulting standards.
Abstract: To address the issues of software product quality, the Joint Technical Committee 1 of the International Organization for Standardization and International Electrotechnical Commission published a set of software product quality standards known as ISO/IEC 9126. These standards specify software product quality's characteristics and subcharacteristics and their metrics. Based on a user survey, this study of the standard helps clarity quality attributes and provides guidance for the resulting standards.
TL;DR: There was no significant difference in the efficacy or response rate between haloperidol and risperidone in the treatment of delirium, and no significant differences in mean Memorial Delirium Assessment Scale scores between groups were found.
TL;DR: A transcriptional adaptation to long-term high-fat intake-induced obesity mouse model revealed a number of previously unappreciated regulatory molecules changed by the HFD and provided interesting information about the molecules involved in the development and maintenance of the obesity phenotype in vivo.
TL;DR: In this paper, the authors examined how Internet startups' venture capital financing and strategic alliances affect these startups' ability to acquire the resources necessary for growth, and found that three factors positively influenced a startup's time to IPO: the better the reputations of participating venture capital firms and strategic alliance partners were, the more money a startup raised, and the larger was the size of a startup network of strategic alliances.
TL;DR: In this article, the effect of different metallic fibers upon friction and wear performance of various brake friction couples was investigated based on a simple experimental formulation, friction materials with different metal fibers (Cu, steel, or Al) were fabricated and then evaluated using a small-scale friction tester.
TL;DR: In this paper, the reduction of NO3−, by Fe0, was carried out using Fe0 powder in unbuffered solutions from pH 2 to greater than 10, where the initial pH of the solution was adjusted to 2, 3, or 4 by addition of HCl, H2SO4, or CH3COOH.
TL;DR: Carbon nanotubes (CNTs) were added to Ultra-high molecular weight polyethylene (UHMWPE) to improve the tribological properties of UHMW PE.
Abstract: Carbon nanotubes (CNTs) were added to Ultra-high molecular weight polyethylene (UHMWPE) to improve the tribological properties of UHMWPE. CNTs which have a diameter of about 10–50 nm, while their length is about 3–5 nm were produced by the catalytic decomposition of acetylene gas using a tube furnace. Ball-on-disc-type wear tests were performed to evaluate the tribological performance of UHMWPE composites reinforced with CNTs. The results showed that addition of carbon nanotube up to 0.5 wt% lowered wear loss significantly and increased friction coefficient slightly. Also through the scanning electron microscope (SEM), the surfaces of UHMWPE were observed and analyzed to discuss the tribological behavior of CNT added UHMWPE.
TL;DR: Plasma resistin concentrations are elevated in patients with type 2 diabetes, but are not associated with insulin resistance or obesity.
Abstract: Resistin is an adipocyte-derived peptide that might play a role in obesity and insulin resistance. However, its role in humans is largely unclear. Although many studies have measured the expression of human resistin in tissues, the circulating concentrations of resistin and its relation to metabolic parameters in humans are unknown. We developed an ELISA for human resistin and measured plasma concentrations in aged individuals with or without type 2 diabetes mellitus. To validate the results of plasma resistin concentrations in our subjects, plasma adiponectin concentrations were also determined, which were higher in nondiabetic subjects than in type 2 diabetic patients and correlated with the homeostasis model assessment for insulin resistance (HOMA-IR). Log-transformed plasma resistin concentrations (log-resistin) were higher in diabetic patients compared with normal individuals (0.50 ± 0.39 vs. 0.28 ± 0.51 ng/ml; P < 0.001), and this difference was significant after controlling for gender and body mass...