Showing papers by "Konkuk University published in 1999"
TL;DR: The results from this study suggest that hepatitis E is enzootic in pigs regardless of whether HEV is endemic in the respective human population.
Abstract: Hepatitis E virus (HEV) is a very important public health concern in many developing countries where epidemics of hepatitis E are common. Sporadic cases of clinical hepatitis E not only occur in these countries but also occur uncommonly in patients with no known epidemiological exposure to HEV in industrialized countries. The source of infection in industrialized countries is unknown but it has been suggested that animals might serve as a reservoir for HEV in both settings. We recently identified and characterized an HEV strain (swine HEV) that infects large numbers of pigs in the United States. To assess the potential of pigs to serve as a global reservoir of HEV, we measured the prevalence of HEV antibodies in pigs in two countries where hepatitis E is endemic and two countries where it is not. Swine herds in all four countries contained many pigs that were seropositive for IgG anti-HEV, although the percentage of seropositive pigs varied greatly from herd to herd. A very limited number of pig handlers in the two endemic countries were also tested and most of them were found to be seropositive for HEV. The results from this study suggest that hepatitis E is enzootic in pigs regardless of whether HEV is endemic in the respective human population. J. Med. Virol. 59:297–302, 1999. Published 1999 Wiley-Liss, Inc.
195 citations
TL;DR: In this article, the defect modes of cholesteric liquid crystals as photonic band gap materials were investigated and the wavelength and reflectivity of defect modes were analyzed in terms of the refractive index of defect layer.
Abstract: We investigate defect modes of cholesteric liquid crystals as photonic band gap materials. For normal incidence of light, cholesteric liquid crystals exhibit total reflection for the circular polarization with the same handedness as that of cholesteric helix. However, the other orthogonal component is completely transmitted. When we replace a thin layer of liquid crystal by an isotropic material as a defect, defect modes are induced for both polarizations of incident light. We analyze the wavelength and reflectivity of the defect modes in terms of the refractive index of defect layer. @S1063-651X~99!09312-5#
150 citations
TL;DR: Bacillus stearothermophilus maltogenic amylase hydrolyzes the first glycosidic linkage of acarbose to give acarviosine–glucose, which was a potent inhibitor for baker's yeast and was an excellent inhibitor for cyclomaltodextrin glucanosyltransferase.
136 citations
TL;DR: In this article, the annular denuder system (ADS) was used to characterize seasonal variations of acidic air pollutants in Seoul, South Korea, over four seasons from October 1996 to September 1997, and the annual mean concentrations of HNO 3, HNO 2, SO 2 and NH 3 in the gas phase were 1.09, 4.51, 17.3 and 4.34
109 citations
TL;DR: Results indicate that psammaplin A has a considerable antibacterial activity, although restricted to a somewhat narrow range of bacteria, probably by inhibiting DNA gyrase.
Abstract: Psammaplin A, a natural bromotyrosine derivative from an associated form of two sponges (Poecillastra sp andJaspis sp) was found to possess the antimicrobial effect on the Grampositive bacteria, especially on methicillin-resistantStaphylococcus aureus (MRSA) The minimal inhibitory concentration of psammaplin A against twenty one MRSAs ranged from 0781 to 625 μg/ml, while that of ciprofloxacin was 0391∼3125 μg/ml Psammaplin A could not bind to penicillin binding protein, but inhibited the DNA synthesis and the DNA gyrase activity with the respective 50% (DNA synthesis) and 100% (DNA gyrase) inhibitory concentration 283 and 100 μ/ml These results indicate that psammaplin A has a considerable antibacterial activity, although restricted to a somewhat narrow range of bacteria, probably by inhibiting DNA gyrase
80 citations
TL;DR: The central hinge region (Gly9-Ile10-Gly11) in an amphipathic antibacterial peptide is considered to play an important role in providing the conformational flexibility required for ion channel formation of the C-terminal hydrophobic alpha-helix on cell membrane.
Abstract: In order to elucidate the structure-antibiotic activity relationships of the peptides, the three-dimensional structures of two hybrid peptides, CA(1-8) - MA(1-12) and CA(1-8) - ME(1-12) in trifluoroethanol-containing aqueous solution were investigated by NMR spectroscopy. Both CA(1-8) - MA(1-12) and CA(1-8) - ME(1-12) have strong antibacterial activity but only CA(1-8) - ME(1-12) has hemolytic activity against human erythrocytes. CA(1-8) - MA(1-12) has a hydrophobic 310-helix of only two turns combined with one short helix in the N-terminus with a flexible hinge section in between. CA(1-8) - MA(1-12) has a severely bent structure in the middle of the peptide. These structural features as well as the low hydrophobicity of CA(1-8) - MA(1-12) seem to be crucial for the selective lysis against the membrane of prokaryotic cells. CA(1-8) - ME(1-12) has an alpha-helical structure of about three turns in the melittin domain and a flexible structure with one turn in the cecropin domain connected with a flexible hinge section in between, and these might be the structural features required for membrane disruption against prokaryotic and eukaryotic cells. The central hinge region (Gly9-Ile10-Gly11) in an amphipathic antibacterial peptide is considered to play an important role in providing the conformational flexibility required for ion channel formation of the C-terminal hydrophobic alpha-helix on cell membrane.
51 citations
TL;DR: In this paper, an empirical correlation between the temperature and entrainment rate at the gas exit of the fluidized bed has been proposed on the basis of the comprehensive experimental data.
Abstract: An empirical correlation, considering the temperature effect but no effects of interparticle forces, on the particle entrainment rate at the gas exit of the fluidized bed has been proposed on the basis of the comprehensive experimental data. The entrainment flux is considered to consist of a constant flux independent of freeboard height and another flux decreasing exponentially with freeboard height. The correlation successfully follows the measured trend where the entrainment rate increased after an initial decrease with increasing temperature and the minimum entrainment rate at a given temperature. The correlation also successfully describes the pressure effect showing that the entrainment rate increases with pressure.
50 citations
TL;DR: Objective(s): To elucidate the relationship between intracellular H2O2 production and embryo development in different oxygen culture conditions.
Abstract: Objective(s): To elucidate the relationship between intracellular H2O2 production and embryo development in different oxygen culture conditions.
Methods: Pronuclear stage embryos were obtained from C57BL/CBA F1 and ICR mice. Measurement of H2O2 level was performed with 2′,7′-dichlorodihydroflourescein diacetate and the number of blastomeres was counted after staining with 4′,6′-diamidino-2-phenylindole.
Results: Regardless of strains, H2O2 level reached a peak at the 2-cell stage in 20% O2. But in embryos cultured in 5% O2 it was significantly lower at the 2-cell and 4-cell stages compared to those from 20% O2. The embryos cultured in 20% O2 showed developmental delay or block, but in 5% O2 these phenomena were overcome and the development was significantly increased with an infrequent fragmentation.
Conclusions: Our data suggest that the 5% O2 decreases the relative concentration of H2O2 and results in improved embryo development in terms of quantity and quality without regard to type of strains.
49 citations
TL;DR: In this article, the contact angle of distilled water and methylene iodide on polyimide surfaces was measured and the dispersion force and the polar force of the rubbed polyimides were measured.
Abstract: To investigate surface free energy of rubbed polyimide surfaces as a function of the rubbing strength, we measured the contact angle of distilled water and methylene iodide on the polyimide surfaces. For this purpose, a main-chain-type and two side-chain-type polyimides were used. The dispersion force (γd) and the polar force (γp) of the rubbed polyimide surfaces was measured. The rubbing induced polarity on the polyimide surfaces. Also, polar forces contributed to form a pretilt angle of liquid crystals on the rubbed polyimide surfaces. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 267–271, 1999
45 citations
TL;DR: In this paper, the authors studied the relationship between an elliptic fibration on a K3 surface and its Jacobian surface and showed that certain K3 surfaces do not admit a non-Jacobian fibration.
Abstract: We study the relationship between an elliptic fibration on an elliptic K3 surface and its Jacobian surface. We give an explicit description of the Picard lattice of the Jacobian surface. Then we use the description to prove that certain K3 surfaces do not admit a non-Jacobian fibration. Moreover, we obtain an inequality involving the determinant of the Picard lattice and the number of components of reducible fibres, which implies, among others, that if an elliptic K3 surface has Picard lattice with relatively small determinant, then every elliptic fibration on it must have a reducible fibre. Some examples of K3 surfaces are discussed.
35 citations
TL;DR: In this paper, a sol-gel derived carbon composite ceramic electrodes (CCCE) containing iron phthalocyanine (FePc) have been used to investigate the electrochemical reduction of nitrite in an acidic solution.
07 Jun 1999
TL;DR: A dynamic load balancing algorithm for network games which takes into account the geographical relationship among game units and the short response time of frequent user interactions is proposed.
Abstract: Network game servers, in which a huge number of users can play a common game through interconnecting network, can be designed in a distributed system architecture with the benefit of scalability, reliability, and cost effectiveness. In order to develop an efficient and scalable network game server system, the paper investigates the issue of load balancing for dynamic change of workload in a network game. We propose a dynamic load balancing algorithm for network games which takes into account the geographical relationship among game units and the short response time of frequent user interactions. We also present simulation results of the proposed algorithm.
TL;DR: The Kaluza-Klein approach to general relativity of 4-dimensional spacetimes was introduced in this paper, where the metric coefficients can be decomposed into sets of fields, which transform as a tensor field, gauge fields, and scalar fields with respect to the infinite dimensional group of the diffeomorphisms of the 2-dimensional fibre space.
01 Jul 1999
TL;DR: In this paper, a new control algorithm is proposed for welding machine, which is the instantaneous output current control method using single chip microprocessor, and as a result of performance test of the proposed system, it was demonstrated that all of the waveform variation parameters could be set individually and the generated spatter is reduced compared to conventional inverter arc welding machine.
Abstract: According to the adoption of inverter circuit topology for welding machine area, the improvement of welding performance con be achieved. However conventional CO/sub 2/ inverter arc welding machine uses the constant voltage characteristics. So the metal transfer is performed under nonoptimum conditions in view of spatter generation. In this paper the new control algorithm is proposed for welding machine, which is the instantaneous output current control method using single chip microprocessor. But the optimum waveform of welding current is still uncertain, as a first step for figuring out the optimized waveforms, this study was performed, and as a result of performance test of the proposed system, it was demonstrated that all of the waveform variation parameters could be set individually and the generated spatter is reduced compared to conventional inverter arc welding machine.
TL;DR: The structural similarity between Abeta25-35 and substance P which is a member of tachykinin family is presented in order to examine the possibility of sharing pathways mediated by tachy Kinin receptors.
Abstract: The three-dimensional structure of β amyloid peptide (25–35) in aqueous solution with 50% (vol/vol) 2,2,2-trifluoroethanol was determined by NMR spectroscopy, β Amyloid pep- tide(Aβ) is the major component of senile plaques found in the brain of patient of Alzheimer's disease. Aβ25-35 is biologically active fragment of Aβ and exhibits some sequence homology with the tachykinin family. In this study, we present the structural similarity between Aβ25-35 and substance P which is a member of tachykinin family in order to examine the possibility of sharing pathways mediated by tachykinin receptors. Both peptides have a-helical structures in their C-terminal regions and aromatic rings or hydrophobic side chains in the center of the helix protrude outside. These conformational features are expected to be the key for the interaction with the receptors.
TL;DR: In this paper, the authors show that the ion-induced secondary electron emission property is enhanced more by the cesium incorporation than by the ion beam assisted depsition, which is a combined effect of densification and reduction of the surface work function.
Journal Article•
TL;DR: In this paper, a geometrically nonlinear nine-node assumed strain shell element with six DOF per node was used to estimate the torsional buckling loads of composite cylinders with angle plies.
Abstract: Buckling of composite cylinders under torsion has been analyzed using the geometrically nonlinear nine-node assumed strain shell element with six DOF per node. Buckling loads are pinpointed by finding the lowest torsion load that makes the determinant of the global tangent stiffness matrix zero in the course of the geometrically nonlinear analysis. Torsional buckling loads calculated from the present method agree well with the linear buckling loads obtained from various shell theories for most composite cylinders. For cylinders with [30/30/-60]s ply orientation, however, large discrepancy between the two buckling loads has been observed. Comparing the numerical test results with experimental data, we conclude that the present method can estimate the torsional buckling loads of composite cylinders with angle plies. The present paper may provide new reference solutions for torsional buckling loads of composite cylinders
TL;DR: Proton longitudinal relaxation data proved that the interactions between NMB with SDS micelle are characterized as extrinsic interaction and Trp4 and Phe9 seem to be important in interaction with receptor.
Journal Article•
TL;DR: It is suggested that the induction of AsPOX in cultured soybean cells during the stationary phase could result, at least in part, by the hydrogen peroxide generated as a result of preceding ethylene production.
Abstract: In cultured soybean cells, a transient ethylene burst in the pre-stationary phase was followed by an induction of ascorbate peroxidase (AsPOX) in the stationary phase. Treatment of cells with the ethylene antagonist, silver thiosulfate (STS), resulted in the suppression of enzyme activity. Application of the ethylene releasing agent 2-chloroethylphosphonic acid (CEPA) in the medium led to an increased enzyme activity when treated in the pre-stationary phase. On the contrary, a remarkable inhibitory effect on enzyme activity was elicited by 1,3-dimethyl-2-thiourea (DMTU), trapping the hydrogen peroxide generated when treated in the stationary phase. Likewise, a steady level of AsPOX transcript was reduced by STS treatment. Furthermore, its effect appeared to be more rapid and prominent during the pre-stationary phase. It is suggested that the induction of AsPOX in cultured soybean cells during the stationary phase could result, at least in part, by the hydrogen peroxide generated as a result of preceding ethylene production.
TL;DR: The surface morphology of rubbed polyimide LC aligning films has been studied by scanning force microscopy in this article, where the authors examined three types of alignment film: HT-210, AL-1051 and AL-8044.
Abstract: The surface morphology of rubbed polyimide LC aligning films has been studied by scanning force microscopy. We examined three types of alignment film: HT-210, AL-1051 (main chain type) and AL-8044 (side chain type) polyimide surfaces. The rubbed polyimide surfaces show anisotropic alignment of the polymer chain cluster, and a microgroove between the ripple pattern streaks. Also, they are periodically oriented along the rubbing direction. The optical phase retardation of the rubbed surface does not increase with increased cumulative time of rubbing, On the other hand, it increases monotonically with increasing rubbing depth.
TL;DR: In this article, coherent phonon oscillations in GaAs/AlGaAs superlattices and multiple quantum wells as a function of the barrier width were studied, and it was shown that coherent interwell plasmons oscillating across the barrier couple correspond to LO phonons.
Abstract: We study coherent phonon oscillations in GaAs/AlGaAs superlattices and multiple quantum wells as a function of the barrier width. Strong, bulklike screened LO phonons accompany bare LO phonons for thin barrier samples, whereas for thicker barrier samples, only the bare LO phonons exist. These results strongly indicate that the coherent interwell plasmons oscillating across the barrier couple to LO phonons. The technique applied is a very sensitive way of probing the superlattice--multiple quantum well transition of collective charge oscillations.
TL;DR: In this paper, the relationship between the optical phase retardation of rubbed polyimide films and the azimuthal anchoring energy was reported, where one main chain type and two side chain type polyimides were used.
Abstract: To study the alignment of liquid crystal molecules, the relationship between the optical phase retardation of rubbed polyimide films and the azimuthal anchoring energy was reported. For this work, we investigated the effects of the side chain of polyimide and the rubbing parameter on optical phase retardation of the rubbed polyimide surfaces and azimuthal anchoring energy. One main chain type and two side chain type polyimide were used.
TL;DR: Nanoparticles with the dimensions of circa 50 nm prepared from the micellar aggregation of diblock copolymers of poly(ethylene oxide) and polycaprolactone were explored as a parenteral carrier system for water-soluble organic drugs in salt form and possess drug-retaining capability at 25°C or below even after free EPM was eliminated from the aqueous phase by dialysis.
Abstract: Nanoparticles with the dimensions of circa 50 nm prepared from the micellar aggregation of diblock copolymers of poly(ethylene oxide) and polycaprolactone (PEO–b–PCL) were explored as a parenteral carrier system for water-soluble organic drugs in salt form. Enalapril maleate (EPM), developed for hypertension and congestive heart failure, was used as a model drug. The nanoparticles from three block copolymers with compositions of 5k–7.5k, 5k–5k, and 5k–2.5k (PEO–b–PCL) exhibited drug-loading efficiency of 38%, 47%, and 26%, respectively, for an equivalent amount of EPM in a 1% (w/v) micelle solution. Particularly, 5k–5k micelles could be incorporated with the model drug up to 47% (w/w) of polymer. Furthermore, these nanoparticles possess drug-retaining capability at 25°C or below even after free EPM was eliminated from the aqueous phase by dialysis. A temperature-responsive release behavior was displayed upon heating to the physiological temperature, 37°C. Drug release from the micelles proceeded in a fairly linear fashion for a duration of about 4–7 days, depending on the composition of the block copolymers. Daily average fractional release was consistent regardless of drug contents in the nanoparticles. In a preliminary animal toxicity test the EPM-loaded micelle solutions were intravenously administered to mice of the ICR strain through the tail vein. The animal subjects received 0.7 mL of EPM micelle solution up to six times and showed normal weight gain and food consumption. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2856–2867, 1999
TL;DR: Analysis showed that the CNS midline cells specified by single-minded gene as well as spitz class genes are required for identity determination of a subset of ventral NBs and for formation of mature neurons and their axon pathways.
Abstract: The Drosophila embryonic central nervous system (CNS) develops from sets of neuroblasts (NBs) which segregate from the ventral neuroectoderm during early embryogenesis. It is not well established how each individual NB in the neuroectoderm acquires its characteristic identity along the dorsal-ventral axis. Since it is known that CNS midline cells and spitz class genes (pointed, rhomboid, single-minded, spitz and Star) are required for the proper patterning of ventral CNS and epidermis originated from the ventral neuroectoderm, this study was carried out to determine the functional roles of the CNS midline cells and spitz class genes in the fate determination of ventral NBs and formation of mature neurons and their axon pathways. Several molecular markers for the identified NBs, neurons, and axon pathways were employed to examine marker gene expression profile, cell lineage and axon pathway formation in the spitz class mutants. This analysis showed that the CNS midline cells specified by single-minded gene as well as spitz class genes are required for identity determination of a subset of ventral NBs and for formation of mature neurons and their axon pathways. This study suggests that the CNS midline cells and spitz class genes are necessary for proper patterning of the ventral neuroectoderm along the dorsal-ventral axis.
TL;DR: The linear span of extended sequences ofperiod 2/sup em/-1 which are constructed from the ideally correlated sequences of period of 2/Sup m/-1 is derived and it is shown that thelinear span of cascaded Gordon-Mills-Welch (GMW) sequences can be derived in the same context.
Abstract: In this correspondence, the linear span of extended sequences of period 2/sup em/-1 which are constructed from the ideally correlated sequences of period of 2/sup m/-1 is derived. It is also shown that the linear span of cascaded Gordon-Mills-Welch (GMW) sequences can be derived in the same context. As examples, the linear span of extended Legendre sequences and cascaded GMW sequences with triple trace are computed.
TL;DR: The data strongly indicate that GHG is a powerful antioxidant against lipid peroxidation and is, therefore, responsible for this prophylactic effect.
Abstract: The antioxidative effect of ganhuangenin (GHG), isolated from Scutellaria baicalensis Georgi, was examined by measuring its ability to suppress the formation of phospatidylcholine hydroperoxide (PCOOH). The results show that a pretreatment with GHG effectively suppressed PCOOH formation, which was initiated by the peroxyl-generating oxidant, AAPH (2,2'-azobis-2-aminopropane hydrochloride). The protective action of GHG against the formation of the PCOOH was observed in liver, lung, and kidney. When compared with other known antioxidants, we found the antioxidative potency of GHG to be greater than that of alpha-tocopherol. Our data strongly indicate that GHG is a powerful antioxidant against lipid peroxidation and is, therefore, responsible for this prophylactic effect.
TL;DR: In this article, the effect of electron bombardment on modification of the structural property and the surface morphology of diamond films, and consequently the field emission properties, was investigated by introducing positive substrate bias, ranging from 0 to 200 V, to the substrate during the growing procedure of diamond at 1, 2, and 3% CH4 concentration.
TL;DR: In this article, an element-base superconvergent stress recovery technique is developed for accurate boundary stress extraction, where higher-order stress fields are assumed for all stress components and higher order elements are used for the construction of necessary matrices.
Abstract: An element-base superconvergent stress recovery technique is developed for accurate boundary stress extraction. In the present method, higher-order stress fields are assumed for all stress components and higher order elements are used for the construction of necessary matrices. Unknown coefficients for the assumed stress field are obtained by minimizing the sum of the stress errors and two equilibrium residuals in the least squares sense. The two residuals are derived based on the principle of virtual work. Numerical examples including a three-dimensional problem have demonstrated that the present method can stably extract very accurate boundary stresses even for coarse meshes. Copyright © 1999 John Wiley & Sons, Ltd.
Journal Article•
TL;DR: The levels of Hg in scalp hair of male subjects were significantly different according to their occupations and age groups, but in females such variation was not detectable, and the Hg levels in fishing village residents were significantly higher than those of Seoul residents.
Abstract: Relationships have been established between the mercury (Hg) levels in human scalp hair and environmental or dietary mercury exposures. The average value of total mercury (THg) in scalp hair of male residents in Seoul city was 1.66 +/- 1.10 ppm (+/- SD) and for methylmercury (MeHg) was 1.02 +/- 0.72 ppm (61% of total Hg). For females, THg was 1.06 +/- 0.46 ppm and MeHg was 0.51 +/- 0.27 ppm (48.8% of total Hg). The levels of Hg in scalp hair of male subjects were significantly different according to their occupations and age groups, but in females such variation was not detectable. The Hg levels in fishing village residents were significantly higher than those of Seoul residents. The concentrations of both THg and MeHg of residents in Korean fishing villages were similar to those of residents in fishing villages of other countries. Correlation between THg and MeHg contents in scalp hair was statistically highly significant.