oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 13 )

2018 ( 25 )

2017 ( 27 )

2016 ( 30 )

Custom range...

Search Results: 1 - 10 of 7210 matches for " Gwon-Chan Yoon "
All listed articles are free for downloading (OA Articles)
Page 1 /7210
Display every page Item
Vibration and Dynamic Response Control of Nonuniform Composite Rotating Blades
Sungsoo Na,Liviu Librescu,Sung-Nam Rim,Gwon-Chan Yoon
International Journal of Rotating Machinery , 2006, DOI: 10.1155/ijrm/2006/13807
Abstract: This paper addresses the free vibration, dynamic response, and the active control of composite rotating pretwisted blades modeled as nonuniform thin-walled beams, fixed at the hub at a setting angle, and incorporating piezoelectrically induced damping capabilities. In this sense, a distributed piezoelectric actuator system activated through the application of an out-of-phase electrical current is used to suppress the dynamic response of the rotating beam subjected to a Heaviside pulse. The blade model incorporates nonclassical effects such as transverse shear, secondary warping, and rotary inertias, and includes the centrifugal and Coriolis force fields. A velocity feedback control law relating the piezoelectrically induced bending moment at the beam tip with appropriately selected kinematical response quantities is used, and the beneficial effects of its implementation upon the closed loop eigenvibration and dynamic characteristics of the blade are highlighted.
Vibration and Dynamic Response Control of Nonuniform Composite Rotating Blades
Sungsoo Na,Liviu Librescu,Sung-Nam Rim,Gwon-Chan Yoon
International Journal of Rotating Machinery , 2006,
Abstract: This paper addresses the free vibration, dynamic response, and the active control of composite rotating pretwisted blades modeled as nonuniform thin-walled beams, fixed at the hub at a setting angle, and incorporating piezoelectrically induced damping capabilities. In this sense, a distributed piezoelectric actuator system activated through the application of an out-of-phase electrical current is used to suppress the dynamic response of the rotating beam subjected to a Heaviside pulse. The blade model incorporates nonclassical effects such as transverse shear, secondary warping, and rotary inertias, and includes the centrifugal and Coriolis force fields. A velocity feedback control law relating the piezoelectrically induced bending moment at the beam tip with appropriately selected kinematical response quantities is used, and the beneficial effects of its implementation upon the closed loop eigenvibration and dynamic characteristics of the blade are highlighted.
A Malicious and Malfunctioning Node Detection Scheme for Wireless Sensor Networks  [PDF]
Seo Hyun Oh, Chan O. Hong, Yoon Hwa Choi
Wireless Sensor Network (WSN) , 2012, DOI: 10.4236/wsn.2012.43012
Abstract: Wireless sensor networks are often used to monitor physical and environmental conditions in various regions where human access is limited. Due to limited resources and deployment in hostile environment, they are vulnerable to faults and malicious attacks. The sensor nodes affected or compromised can send erroneous data or misleading reports to base station. Hence identifying malicious and faulty nodes in an accurate and timely manner is important to provide reliable functioning of the networks. In this paper, we present a malicious and malfunctioning node detection scheme using dual-weighted trust evaluation in a hierarchical sensor network. Malicious nodes are effectively detected in the presence of natural faults and noise without sacrificing fault-free nodes. Simulation results show that the proposed scheme outperforms some existing schemes in terms of mis-detection rate and event detection accuracy, while maintaining comparable performance in malicious node detection rate and false alarm rate.
Vegetation of mono-layer landfill cover made of coal bottom ash and soil by compost application  [PDF]
Seul Bi Lee, Sang Yoon Kim, Chan Yu, Soon-Oh Kim, Pil Joo Kim
Journal of Agricultural Chemistry and Environment (JACEN) , 2013, DOI: 10.4236/jacen.2013.23008
Abstract: Monolayer barriers called evapotranspiration (ET) covers were developed as alternative final cover systems in waste landfills but high-quality soil remains a limiting factor in these cover systems. Coal bottom ash was evaluated to be a very good alternative to soil in previous tests and a combination of soil (65% wt.wt-1) and coal bottom ash (35% wt.wt-1) was evaluated to be the most feasible materials for ET cover systems. In our pot test, selected manure compost as soil amendment for the composite ET cover system, which was made of soil and bottom ash at ca. 40 Mg.ha-1 application level was very effective to promote vegetation growth of three plants; namely, garden cosmos (Cosmosbipinnatus), Chinese bushclover (Lespedezacuneata), and leafy lespedeza (Lespedeza cyrtobotrya). To evaluate the effect of compost application on plant growth in an ET vegetative cover system, two couples of lysimeters, packed with soil and a mixture of soil and bottom ash, were installed in a pilot landfill cover system in 2007. Manure composts were applied at the rates of 0 and  40 Mg.ha-11before sowing the five plant species, i.e.indigo-bush (Amorphafruticosa), Japanese mugwort (Artemisia princeps, Arundinella hirta, Lespedezacuneata, and Lespedezacyrtobotrya). Unseeded native plant (green foxtail,Setaria viridis) was dominant in all treatments in the 1st year after installation while the growth of the sown plants significantly improved over the years. Total biomass productivity significantly increased with manure compost application, and more significantly increased in the composite ET cover made of soil and bottom ash treatment compared to the single soil ET cover, mainly due to more improved soil nutrient levels promoting vegetation growth and maintaining the vegetation system. The use of bottom ash as a mixing material in ET cover systems has a strong potential as an alternative to fine-grained soils, and manure compost addition can effectively enhance vegetative propagation in ET cover systems.
New Concept for Calculating DC Harmonic Voltages and Currents in BTB HVDC Converters  [PDF]
Chan-Ki Kim, Seong-Doo Lee, Soon-Ho Choi, Yong-Beum Yoon
Journal of Power and Energy Engineering (JPEE) , 2014, DOI: 10.4236/jpee.2014.211005
Abstract: This paper deals with a new concept for calculating DC harmonic voltages and currents of line- commutated HVDC systems. In contrast to the conventional method, this method is useful for BTB (Back-To-Back) HVDC systems without smoothing reactors or PTP (Point-To-Point) with very short transmission line. This method proposes a new direction for HVDC system design and analysis. The proposed method is applied to a 50 Hz/60 Hz BTB test system and a synchronized BTB test system. After simulation and verification, the new results are introduced.
Low Complexity MIMO Detection based on Belief Propagation over Pair-wise Graphs
Seokhyun Yoon,Chan-Byoung Chae
Mathematics , 2013,
Abstract: This paper considers belief propagation algorithm over pair-wise graphical models to develop low complexity, iterative multiple-input multiple-output (MIMO) detectors. The pair-wise graphical model is a bipartite graph where a pair of variable nodes are related by an observation node represented by the bivariate Gaussian function obtained by marginalizing the posterior joint probability density under the Gaussian input assumption. Specifically, we consider two types of pair-wise models, the fully connected and ring-type. The pair-wise graphs are sparse, compared to the conventional graphical model in [18], insofar as the number of edges connected to an observation node (edge degree) is only two. Consequently the computations are much easier than those of maximum likelihood (ML) detection, which are similar to the belief propagation (BP) that is run over the fully connected bipartite graph. The link level performance for non-Gaussian input is evaluated via simulations, and the results show the validity of the proposed algorithms. We also customize the algorithm with Gaussian input assumption to obtain the Gaussian BP run over the two pair-wise graphical models and, for the ring-type, we prove its convergence in mean to the linear minimum mean square error (MMSE) estimates. Since the maximum a posterior (MAP) estimator for Gaussian input is equivalent to the linear MMSE estimator, it shows the optimality, in mean, of the scheme for Gaussian input.
Bis(4,4′′-difluoro-1,1′:3′,1′′-terphenyl-2′-carboxylato-κO)tetrakis(methanol-κO)calcium methanol tetrasolvate
Namseok Kim,Heeso Noh,Sungho Yoon,Chan Ryang Park
Acta Crystallographica Section E , 2013, DOI: 10.1107/s1600536813000044
Abstract: In the title compound, [Ca(C19H11F2O2)2(CH3OH)4]·4CH3OH, the Ca2+ ion is located on an inversion centre and is hexacoordinated by two O atoms of two 4,4′′-difluoro-1,1′:3′,1′′-terphenyl-2′-carboxylate ligands and four O atoms of four methanol ligands, forming a CaO6 polyhedron with a slightly distorted octahedral coordination geometry. The Ca—O—C angle between the carboxylate group and the calcium ion is 171.8 (2)°. Two types of intermolecular hydrogen-bond interactions (C=O...H and O—H...O) between the carboxylate ligand, the methanol solvent molecules and the coordinating methanol ligands generate a two-dimensional network parallel to (001).
Bisphosphonate use and gastrointestinal tract cancer risk: Meta-analysis of observational studies
Yun Hwan Oh,Chan Yoon,Sang Min Park
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i40.5779
Abstract: AIM: To perform a meta-analysis of observational studies to further elucidate the relationship between oral bisphosphonate use and gastrointestinal cancer risk. METHODS: Systematic literature search was conducted in MEDLINE, EMBASE, and the Cochrane Library to identify studies through January 2011. Search terms were “bisphosphonates” or trade names of the drugs, and “observational studies” or “cohort studies” or “case-control studies”. Two evaluators reviewed and selected articles on the basis of predetermined selection criteria as followed: (1) observational studies (case-control or cohort studies) on bisphosphonate use; (2) with at least 2 years of follow-up; and (3) reported data on the incidence of cancer diagnosis. The DerSimonian and Laird random effects model were used to calculate the pooled relative risk (RR) with 95% confidence interval (CI). Two-by-two contingency table was used to calculate the outcomes not suitable for meta-analysis. Subgroup meta-analyses were conducted for the type of cancer (esophageal, gastric and colorectal cancers). Sensitivity analyses were performed to examine the effect sizes when only studies with long-term follow-up (mean 5 years; subgroup 3 years) were included. RESULTS: Of 740 screened articles, 3 cohort studies and 3 case-control studies were included in the analyses. At first, 4 cohort studies and 3 case-control studies were selected for the analyses but one cohort study was excluded because the cancer outcomes were not categorized by type of gastrointestinal cancer. More than 124 686 subjects participated in the 3 cohort studies. The mean follow-up time in all of the cohort studies combined was approximately 3.88 years. The 3 case-control studies reported 3070 esophageal cancer cases and 15 417 controls, 2018 gastric cancer cases and 10 007 controls, and 11 574 colorectal cancer cases and 53 955 controls. The percentage of study participants who used bisphosphonate was 2.8% among the cases and 2.9% among the controls. The meta-analysis of all the studies found no significant association between bisphosphonate use and gastrointestinal cancer. Also no statistically significant association was found in a meta-analysis of long-term follow-up studies. There was no negative association between bisphosphonate use and the incidence of esophageal cancer in the overall analysis (RR 0.96, 95% CI: 0.65-1.42, I2 = 52.8%, P = 0.076) and no statistically significant association with long-term follow-up (RR 1.74, 95% CI: 0.97-3.10, I2 = 58.8%, P = 0.119). No negative association was found in the studies reporting the risk o
Lupeol Is One of Active Components in the Extract of Chrysanthemum indicum Linne That Inhibits LMP1-Induced NF-κB Activation
Se Chan Kang, Sue Yeon Lim, Yoon-Jae Song
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0082688
Abstract: We have previously reported that seventy percent ethanol extract of Chrysanthemum indicum Linne (CIE) strongly reduces Epstein-Barr virus (EBV)-transformed lymphoblastoid cell line (LCL) survival by inhibiting virus-encoded latent infection membrane protein 1 (LMP1)-induced NF-κB activation. To identify an active compound(s) in CIE that inhibits LMP1-induced NF-κB activation, activity-guided fractionation was employed. The CH2Cl2 fraction of CIE strongly reduced LMP1-induced NF-κB activation and LCL viability with relatively low cytotoxic effects on primary human foreskin fibroblast (HFF), HeLa or Burkitt’s lymphoma (BL41) cells. Furthermore, lupeol, a pentacyclic triterpene, was identified in the CH2Cl2 fraction of CIE to attenuate LMP1-induced NF-κB activation and LCL viability. This study demonstrates that lupeol is one of active compounds in the CH2Cl2 fraction of CIE that inhibits LMP1-induced NF-κB activation and reduces NF-κB-dependent LCL viability.
Simple proofs for duality of generalized minimum poset weights and weight distributions of (Near-)MDS poset codes
Dae San Kim,Dong Chan Kim,Jong Yoon Hyun
Mathematics , 2011,
Abstract: In 1991, Wei introduced generalized minimum Hamming weights for linear codes and showed their monotonicity and duality. Recently, several authors extended these results to the case of generalized minimum poset weights by using different methods. Here, we would like to prove the duality by using matroid theory. This gives yet another and very simple proof of it. In particular, our argument will make it clear that the duality follows from the well-known relation between the rank function and the corank function of a matroid. In addition, we derive the weight distributions of linear MDS and Near-MDS poset codes in the same spirit.
Page 1 /7210
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.